It is a versatile imaging tool

Date:14/02/2008 URL: http://www.thehindu.com/thehindu/seta/2008/02/14/stories/
2008021450031500.htm



It is a versatile imaging tool

Scanners that use combined positron emission tomography (PET) and computed tomography (CT) have been proving their potential as versatile medical imaging tools since 2000 when they became commercially available.

A PET scanner uses small amounts of radioactive pharmaceuticals targeted at specific organs, bone or tissues. Development of radiopharmaceuticals such as fluoro-deoxyglucose (FDG) which can act as a marker for sugar metabolism enhanced its potential u se. FDG contains Fl-18, a positron emitting radionuclide, whose presence will help to trace and locate the sites where the molecules get accumulated.
Special camera

A special camera that works with a computer provides pictures of the area of the body being imaged. Cancer cells often grow and multiply uncontrollably. They consume enormous amounts of energy. Basically, this energy comes from burning glucose.

Cancer cells metabolise sugar at higher rates than normal cells, and the radiopharmaceutical is drawn in higher amounts to cancerous areas (Society of Nuclear Medicine [SNM] Release, December 12, 2007)

PET scans produce three-dimensional images of the precise distribution of FDG in the body; FDG plays the role of a marker for the disease and its spread. CT scans on the other hand show the details of the anatomical structures.

Since 2000, when Beyer, Townsend and others introduced the concept of PET-CT imaging, state-of-the–art CT imaging technology has been combined with high-end PET systems (The Journal of Nuclear Medicine [JNM], January 2007).

Recently, researchers claimed that PET-CT imaging is superior to conventional imaging in detecting cancers in children (JNM, December 2007). The modality provides additional information, possibly sparing young patients from being overtreated.
Plaque inflammation

PET-CT offers a superior view of atherosclerosis plaque inflammation — a process in which deposits of fats, cholesterol, cellular waste products and other substances, collectively called plaque, builds up in the inner linings of the artery and limits the flow of blood through it (innovations-report.com, June 6, 2006).

PET-CT may be able to assess biologically active plaques; these are of concern as they may lead to “deadly consequences when they misbehave.”

Disease processes may obstruct blood vessels. Specialists insert prosthetic grafts to restore and ensure blood circulation.

According to Ora Israel, director of nuclear medicine and research operations at Rambam Health Care Campus, in Haifa, Israel, graft infection is a rare, but potentially severe complication occurring at a rate ranging between 0.5 and 5 per cent following prosthetic vascular reconstruction (ZAMP Bionews, June 5th, 2007).

Infection imaging

PET-CT imaging effectively diagnoses and differentiates infection, Israeli researchers noted at the 54th Annual Meeting of the SNM. Surgeons remove the infected blood vessel grafts in a complex surgical procedure.

“Sparing unnecessary high risk operations in patients…is of major significance” Dr Israel clarified. “PET-CT imaging can effectively diagnose graft involvement and differentiate it from infection that affects only soft tissue…in its vicinity,” she added (ZAMP Bionews, June 5th 2007)
Cancer screening

Can we justify using PET-CT for population screening for cancer? “Recommendations and decisions regarding cancer screening should be based on reliable data, not good intention, assumptions or speculation …”

“…We conclude from the available data that neither CT nor PET-CT cancer screening is currently warranted…The clinical and statistical relevance of occasionally detected cancers is likely too low to justify population wide screening efforts with these modalities” (The JNM, Supplement, January 2007).

The Journal of Nuclear Medicine, the scientific publication of the Society of Nuclear Medicine (SNM), U.S., published two supplements on PET-CT, one in 2005 and the second in January 2007. Both are available on the web.

As on January 2007, specialists are using more than 1700 PET and PET-CT units in the U.S. India has 15 PET scanners, nine of them are PET-CT; more will be installed in the near future.

Indian nuclear medicine specialists have been providing excellent service though the facilities available in India are too meagre.

Diagnostic nuclear medicine services are admittedly lucrative. Nuclear medicine physicians must collaborate and initiate well focused clinical research and development programmes to improve their professional competence and to create more specialists in the country.

K.S. PARTHASARATHY

Former Secretary, AERB
ksparth@yahoo.co.uk

© Copyright 2000 - 2008 The Hindu

MRI Images show damage caused by secondary smoking

January 3, 2008
MRI images show damage caused by secondary smoking
Bright images of minute structural damage in smokers’ lungs were obtained

• Prolonged exposure to cigarette smoke may
cause passageways in the lungs to break down
---------------------------------------------------------------
• The scanner measured how far the helium atoms
Moved or diffused inside the lungs
-----------------------------------------------------------------
The health impact of second hand smoke has been very controversial (The Hindu, May 23, 2003). Physicians always suspected that second-hand smoke caused microscopic structural damage deep into the lungs. The damage was too tiny to be detected by any medical imaging tool.
Happy ending
Their suspicion had a happy ending, when Dr. Chengbo Wang, a magnetic resonance physicist and his radiologist colleagues in the Department of Radiology at the Children’s Hospital of Philadelphia teamed up with specialists at the University of Virginia School of Medicine to obtain bright medical images of the microscopic structural damage in the lungs of smokers by using a special type of magnetic resonance imaging.
They presented their findings on November 26 this year at the 93rd annual meeting of the Radiological Society of North America (RSNA) at Chicago. They studied 60 adults between ages 41 and 79; Forty five of them never smoked. They divided the non-smokers into groups with low and high exposure to second hand smoke.
The high exposure group smokers had lived with a smoker for at least 10 years, often during childhood (EurekAlert, November 26). The 15 current or former smokers formed the control group.
The research groups inhaled a mixture of nitrogen and He-3, a special type of helium made by polarizing it to make it more visible in the MRI. The researchers adjusted the MRI to take images showing this helium gas in the tissue.
The scanner measured how far the helium atoms moved or diffused inside the lungs during a time period-1.5 seconds-in the present study. The researchers could detect changes deep in the airways and sacs in the lungs.
Prolonged exposure to cigarette smoke may cause the passageways to break down; they may become enlarged; holes may develop. The helium atoms moved greater distance than in the lungs of normal subjects.
One-third of the non-smokers with high exposures to secondhand cigarette smoke had structural changes in their lungs similar to those found in smokers.
Paradoxical results
The researchers interpreted these changes as early signs of damage, representing very mild form of emphysema. Emphysema is a major cause of death in the US and is commonly found in heavy smokers (EurekAlert, Nov 26).
The researchers got some paradoxical results. Among two-thirds of the high exposure group of non-smokers, diffusion measurements were lower than those in the low exposure group.
Dr Wang argued that diffusion is lower in the group as their airways narrowed because of chronic bronchitis. Dr.Katarzyna Macura of John Hopkins School of Medicine, who moderated the RSNA session, noted that the results should be considered preliminary.
Study too small
She wanted animal studies to elucidate and confirm the apparent structural differences (medpage TODAY, Nov 27). She clarified that the study was too small to provide evidence of a cause and effect.
The detection of minute changes in lung is possible now because nearly 30 years ago scientists at Mainz University developed techniques to polarize nuclear spins of isotopes such as helium-3, an isotope which is extremely rare in nature. He-3 became available via the beta decay of tritium (CERN courier, Oct 2, 2001).
Scientists could use a laser beam to polarize helium gas; polarized helium-3 gas is more visible on MRI. Optical pumping of metastable helium-3 atoms can supply relatively large amounts of highly polarized gas.
The magnetic signals from these are a thousand times as large as those normally seen magnetic resonance imaging (CERN Courier, Oct 2, 2001).
Storage and transport of polarized gas from laboratory to hospital is a major challenge. The polarized helium atoms would lose their spin orientation when they collide with the walls of their containers.
Gas storage
Scientists found that they can store the gas at pressures of up to 10 bar for more than 100hours in glass vessels with their inner surfaces coated with a few mono layers of caesium.
Researchers at the Mainz University demonstrated the potential usefulness of He-3 techniques in human lung imaging in 1995. Dr. Wang and his colleagues applied the technique to study microscopic changes in the lungs of smokers.
Dr. Wang hoped that a conclusive study that demonstrates that breathing secondhand smoke can injure the lungs will push legislation prohibiting public exposure.
K.S.PARTHASARATHY
former Secretary, AERB
(ksparth@yahoo.co.uk)

Bhabha’s dream comes true

This article reminds the reader of the early years of atomic energy in India. Dr Bhabha wanted that the Government should use tyhe then available fairly inexpensive electric power to produce heavy water. He wanted the company producing heavy water should be under the Defence Ministry, The produce should be left to the Atomic Energy commission for its own use or sale. It took several years to fulfill Bhabha's dream.The Heavy Water Board, the agency producing heavy water lives up to the expectations of Dr.Bhabha.

K.S.Parthasarathy



SCIENCE&TECHNOLOGY
Friday,February 1,2008,Chandigarh,India
Bhabha’s dream comes true
K.S. Parthasarathy
Scientists and engineers in the Heavy Water Board (HWB), Department of Atomic Energy (DAE) have every reason to be proud. They fulfilled the dreams of Dr Homi Bhabha whose death anniversary was on January 24. The Board exported heavy water to South Korea seven times and once to China.
Last year, HWB supplied 4,400 kg of high quality, nuclear grade heavy water to Spectra Gases Inc. USA. HWB is emerging as a major exporter of this commercially important strategic material. A peep into history is in order.
In a note on the organisation of atomic energy research in India, sent to Jawaharlal Nehru on April 26, 1948, Dr Homi Bhabha wanted that the government “should explore immediately the possibility of utilising the cheap hydroelectric power in India for manufacturing heavy water on the one hand to our own requirements in a pile and on the other for sale to other countries”.
He desired that the government should come to an agreement with the Governments or atomic energy agencies of one or more countries such as Great Britain, France and Norway. “…that was the quickest and the most desirable way to develop atomic energy in India” he argued
Why did he bracket Norway with France and Great Britain? He knew that Norway had the knowhow to produce heavy water, an essential raw material to produce atomic energy. In 1942, Norway was producing 1.5 tons of heavy water annually at its Rjukan plant. (Smart Norwegian saboteurs damaged the plant in 1943;They did not want Germans to get any advantage. The old hydro power station and plant have been preserved as the monument of Norway’s heavy water industry.)
The “factory should be set up for the purpose under the Defence Ministry and put under the same security measures as the armaments factories of that Ministry”. Bhabha drove home the strategic importance of heavy water.
He wanted that “the heavy water produced should be at the disposal of the Atomic Energy Commission for use or sale”. Bhabha wanted to thwart a possible future turf war with the army!
At the second meeting of the Board of Research on Atomic Energy held in Bombay on 9th and 10th April 1948, Bhabha secured approval for three resolutions; one of which recommended that the government should investigate the feasibility of producing heavy water in India.
In the note enclosing the resolutions, Bhabha proposed to Nehru the setting up of a three Member Atomic Energy Commission directly under the Prime Minister as “the present Board……..cannot be entrusted with this work since it is an advisory body…….composed of 28 members including officials, scientists and industrialists”. “Secret matters cannot be dealt with under this organisation”, Bhabha asserted.
In 1954, Dr Bhabha convinced Nehru about setting up a fertiliser cum heavy water plant at Nangal. He argued that cheap electric power (1.35 paisa per kilowatt-hr, revised later to 6 paisa per kilowatt-hr!) will be available from the Bhakra-Nangal Hydel Project. Nangal plant produced the first drop of heavy water on August 9, 1962. Nangal plant was the largest plant of this type in the world.
Bhabha waited for over 14 years (from April 1948 to August 1962) to realise his dream to produce heavy water indigenously. The Heavy Water Board executed the first export order to South Korea in May 1998, just under 36 years later.
If Dr Bhabha were alive today, he would have congratulated the board for its achievements. He might have also expressed his dissatisfaction, as it took too long to fulfill his dream.
HWB faced many trials and tribulations (the difficulties in operating heavy water plants with fertiliser factories, power scarcity, export controls, poor national industrial infrastructure among others) in mastering a technology known only to a handful of advanced countries.
HWS has an impressive list of achievements, including energy conservation measures, maintenance of high capacity factors for the plants and product diversification among others.
The board kept the Nuclear Power Corporation of India Limited in good humour by supplying heavy water to the pressurised heavy water reactors in the country.
Overall, the board lives up to the expectations of Dr Bhabha,the architect of nuclear India.
Dr K.S.Parthasarathy is former Secretary, Atomic Energy Regulatory Board.

Missing footprints of A-bomb fallout in Himalayan ice fields

The article highlights the fact that nuclear fallout footprints were missing when a US-Chinese team examined the ice cores collected from a glacier in the Tibetan Plateau. The researchers observe that this may mean dwindling fresh water supplies for half the Indian population after a few decades
K.S.Parthasarathy




Missing footprints of A-bomb fallout in Himalayan ice fields
It means dwindling fresh water supply in future to half the Indian population
________________________________________
The total area of glaciers in the Tibetan plateau may shrink by 80 per cent by 2030
Glaciers worldwide are a barometer for global warming
________________________________________
Ice cores drilled from the peak of a Himalayan ice field in 2006 by researchers revealed a chilling reality. Unlike the cores retrieved worldwide, the ice cores from the Himalayan glaciers did not contain the footprints of fallout radioactivity from nuclear weapons testing.
Lonnie Thomson, distinguished professor of earth sciences at Ohio State University and a researcher from the Byrd Polar Research Centre, who led the team revealed the findings while addressing the American Geophysical Union at San Francisco on December 12, 2007.
The radioactive fallout from 520 atmospheric tests during the 1950s and early 1960s spread far and wide and deposited on various surfaces. The missing radioactivity originating as fallout from atmospheric tests during the 1950s and 1960s routinely provides researchers with a benchmark against which they can gauge how much new ice has accumulated on a glacier or ice field (EurekAlert, Dec 11, 2007). In 2006, the joint US-Chinese team drilled four cores from Naimona’nyi, a glacier 6050 metres high on the Tibetan Plateau. Missing nuclear fallout markers means that this Tibetan ice field has been shrinking at least since the atom bomb tests 50 years ago. Melting ice from the Himalayan glaciers is the source of fresh water for Ganges, Indus and Brahmaputra.
Thompson estimated that there are about 12,000 cubic metres of fresh water stored in the glaciers throughout the Himalayas.
Radioactivity signals
They release melt water each year and feed the rivers downstream. These ice fields are shrinking. If they are eventually lost, 500 million people who depend on glacier-fed streams will suffer critical shortage of water.
The radioactivity signals from strontium-90, caesium-136, tritium (H-3) and chlorine-36 were present in ice cores from Polar Regions and from tropical glaciers around the globe.
This means that the ice fields from these regions retained snow that fell during the last fifty years.
Ice cores
In 2000, Dr Thompson led a team of researchers and retrieved ice cores from Kilimanjaro’s northern ice fields. They found fallout footprints only 1.8 metres below the surface.
“By 2006, the surface of that ice field had lost more than 2.5 metres of solid ice (and hence recorded time) — including ice containing that signal.
Had we drilled those cores in 2006 rather than 2000, the radioactive horizon would be absent — like it is now on Naimona’nyi in the Himalayas” Dr Thompson said (EurekAlert, 2007). “If what is happening on Naimona’nyi is characteristic of the Himalayan glaciers, glacial melt water will eventually dwindle with substantial consequences for a tremendous number of people,” Dr Thompson warned. Researchers estimate that there are nearly 15,000 glaciers within the Himalayan mountain chain forming the main repository for fresh water in that part of the world. The total area of glaciers in the Tibetan plateau may shrink by 80 per cent by the year 2030 (EurekAlert, Dec 11).
D.P. Dobhal, a glaciologist with the Wadia Institute of Himalayan Geology, regularly measures the changes in the size and volume of the Chorabari glacier in the Himalayas (The NYT, July13, 2007).
Chorabari’s snout
Dhobhal estimated that the Chorabari’s snout (where glacier melt water empties out in to the river) retreated 29.5 ft every year for the last three years (The NYT, July 17,2007). According to the New York Times, the Indian Space Research Organization, using satellite imaging to gauge the changes to 466 glaciers has found more than a 20 per cent reduction in size from 1962 to 2001 with bigger glaciers breaking into smaller pieces each retreating faster than its parent.
Mean air temperature
Glaciers worldwide are a barometer for global warming (The NYT, July 17, 2007). The New York Times quoted a recent study which found that the mean air temperature in the northwestern Himalayan range had risen by 2.2 degrees Celsius in the last two decades, a rate considerably more than the rate of increase over the last 100 years.
The impact of global warming is getting attention worldwide. Professor Thompson based his findings on scientific observations. Other studies corroborated them.
Let us hope that Professor Thompson’s predictions may not come true; what is worrying is that it may remain so; just a hope!
K.S. PARTHASARATHY
Former Secretary, AERB
( ksparth@yahoo.co.uk)
© Copyright 2000 - 2008 The Hindu

India : Nuclear Technology Scenario

India: Nuclear Technology Scenario
by K S Parthasarathy
RECENT developments in nuclear technology and allied fields have given nuclear advocacy groups and their well-wishers in India, an inspiration for calm contemplation; an occasion to assess the weaknesses of the programme and to appreciate its inherent strengths.
India has made laudable progress in operating the entire nuclear fuel cycle consisting of mining, milling, fuel fabrication, nuclear reactor operation and spent fuel management. The latest annual report of the Department of Atomic Energy (DAE, 2006-07) amply demonstrates “a paradigm shift in terms of far greater mobilisation of resources and technologies” for uranium exploration activities.
The Atomic Minerals Directorate for Exploration and Research (AMD) established over 6600 tonnes of additional uranium resources at Lostoin, Wahkyn, West Khasi Hills in Meghalaya, Chitrial, Nalgonda district, Andhra Pradesh and Rahul, Sikar district in Rajasthan. The agency is leaving no stones unturned to locate uranium resources across different regions in the country.
Prospecting and drilling for the precious resource continued with renewed vigour in several areas in Andhra Pradesh, Karnataka and Madhya Pradesh. AMD estimated over 120 million tonnes of total heavy mineral resources as an inferred category along the 30 km coastline in Puri district, Orissa. The operating units of the Uranium Corporation of India Limited (UCIL) showed improved capacity utilisation during the year. Narwapahar mine and Jaduguda plant maintained their excellent performance; the quantity of uranium ore they produced and processed, respectively exceeded their production capacities.
The Nuclear Fuel Complex (NFC) met the fuel requirements of all the operating pressurised heavy water reactors and boiling water reactors. NFC supplied the entire initial full core fuel requirement of unit 3 of the Tarapur Atomic Power Project (TAPP-3), the reactor internals of unit 6 of Rajasthan Atomic Power Project (RAPP-6), the coolant tubes and Garter springs for replacement in Units 1 and 2 of the Narora Atomic Power Station and the first supply of titanium half alloy hydraulic tubes (a critical component in the Light Combat Aircraft) for the Aeronautical Development Authority. The scientists and engineers at the India Gandhi Centre for Atomic Research operated the Fast Breeder Test Reactor (FBTR) at Kalpakkam without any failure of the mixed carbide fuel used, for a record length of time. Four sodium pumps operated trouble free for 5,50,000 hours. The experience gained in operating FBTR will be invaluable in our fast breeder reactor programme.
The construction of the Prototype Fast Breeder Reactor (PFBR) and related facilities at Kalpakkam is on course. The manufacture of a few important systems and components of the 300 MWe Advanced Heavy Water Reactor (AHWR) being developed by Bhabha Atomic Research Centre have been completed.
During 2006-07, the Nuclear Power Corporation of India Limited (NPCIL) achieved the target capacity addition of 1300 MWe in the Xth plan with the commissioning of two nuclear power reactors of 540 MWe capacity at Tarapur (TAPP-3 and 4) and two units of 220 MWe at Kaiga (Kaiga-3 and 4). Unit 4 of the Rajasthan Atomic Power Station operated continuously for 373 days, breaking an earlier record. Unit 1 of the Kaiga Atomic Power Station operated non-stop for 356 days. Units 1 and 2 of the Tarapur Atomic Power Station, the first nuclear power station in the country, recorded the highest power generation since the station began its commercial operation.
The total generation including wind power generation at Kudankulam was 398 million units more than the last year. But the overall capacity factor for the nuclear power plants was low at 63 per cent. The annual report of NPCIL for 2006-07 noted that the capacity factor will improve proportionately when the mismatch between fuel supply and generation is resolved, shortly. NPCIL successfully completed the life extension and safety up-gradation of unit 1 of the Narora Atomic Power Station (NAPS-1) within the estimated cost and time. The Raja Ramanna Centre for Advanced Technology (RRCAT) and NPCIL developed various laser-based tools indigenously to reduce radiation exposure to workers involved in en masse replacement of coolant tubes at NAPS-1; this was possible as the duration in which the coolant tubes were removed and replaced became shorter, when these advanced tools were used.
NPCIL concentrates its research and development (R&D) activities in 21 areas in nuclear and electronic systems. These include new and improvised technologies to enhance safety, safety experiments to validate design parameters, methods to reduce operation and maintenance costs of operating units, management of radioactive waste, ageing and degradation studies, remote inspection, maintenance, emergency handling and refurbishment/repair technologies, indigenisation of processes, equipment and components, development of electronics and computer-based systems for new projects and up-gradation of systems for existing nuclear power plants among others.
The sophisticated tools used by NPCIL included a “remote operated vehicle” to carry out in situ inspection to identify locations where suspected leakages on the steel liners in the calandria vault of KAPS-1 occur and an indigenously developed automatic cutting/beveling machine for feeder pipe replacement during the en masse coolant channel replacement campaign. This helped to reduce plant outage time and to save substantial foreign exchange.
The NPCIL’s annual report for 2006-07 indicates that its R&D expenditure was Rs 120.43 million or 0.33 per cent of the turnover. It registered a considerable increase over the amount for 2005-06 of Rs 61.9 million or 0.17 per cent of the turnover.
The enchanting mustard fields with Narora Atomic Power Station in its background, the colourful and beautiful birds like the Red Avadavat at the Rajasthan Atomic Power Station, the mixed group of painted storks, grey pelicans and cormorants near the Kudankulam project site and a variety of butterflies at the Madras Atomic Power Station; NPCIL’s annual report contains the images of “a microcosm of the ideal eco-friendly biosphere.” I wonder how the NPCIL staff missed the shoal of colourful fish swimming against the water currents at the outfall of Rajasthan Atomic Power Station. Nuclear stations in India show that they can exist harmoniously with flora and fauna at each location.

Radiation workers and infertility,impotence

Radiation workers and infertility, impotence

There is no scientific evidence that radiation exposure will cause impotence

Temporary sterility may occur at a lower dose of 0.15Gy (150mGy) in a few months post exposure

All available resources need to be used while counselling persons exposed to radiation

Ill-informed radiation workers have very exaggerated notions about the health effects of ionizing radiation. Fortunately, they are a minority. They rarely get opportunities to clear their doubts. Often, they are reluctant to ask. More so, if their doubts are on intensely private topics such as the impact, if any, of radiation exposure on fertility and sexual performance!

Sterility due to radiation exposure is a deterministic effect.

These effects do not occur until the radiation dose reaches a minimum threshold. For instance, the threshold dose for permanent sterility in the male for a single absorbed dose in the testes is about 3.5Gy (3,500mGy) to 6Gy (6,000mGy).
Speedy recovery

Temporary sterility may occur at a lower dose of 0.15Gy (150mGy) after a few months post exposure. It may continue for some months.

The exposed person will recover after a few months. (Gy is a unit of radiation dose; since Gy is large, milligray (mGy) — a dose equal to one thousandth of a Gy — is commonly used; the annual dose limit for radiation workers recommended by the Atomic Energy Regulatory Board (AERB) is 30 mGy for x-rays, gamma rays and electrons; average dose to radiation workers is a fraction of a mGY to a few mGy).

The annual reports of AERB contain relevant details about the radiation doses to workers in India (please see www.aerb.gov.in ).

As the doses received by different groups of radiation workers are several hundred to several thousand times lower than the threshold dose, no worker will suffer sterility due to radiation exposure.

Workers in India have been handling radiation sources for the past several decades. Over the years, there were a few serious incidents involving high radiation doses to individuals who carried sources inadvertently.

There has not been even a single instance of any worker becoming permanently sterile due to occupational radiation exposure. There is no scientific evidence that radiation exposure will cause impotence.
Scientific facts

Publication 60 of the ICRP contains scientific facts about radiation exposure and health effects including sterility. Patients trust their physicians. But few physicians have adequate knowledge in the subject. This became evident during the radiation protection appreciation programmes arranged by AERB a few years ago.
Wrong advice

According to WHO, 10 to 15 per cent of Indian couples are sterile. An exposed person may not get the right advice if he approaches homeopaths and doctors practicing alternative medicine; they are not equipped to offer counsel.

I came across an instance in which in spite of the ‘advice,’ he received, an exposed worker was worried over his erectile dysfunction, which he wrongly attributed to radiation exposure.

Apparently, he had less faith in the really competent physician who offered correct advice!

Scholarly discussion with facts and figures on radiation and its effects has a role to play during medical counselling; but that alone may not reassure an exposed worker.

While researching to write this paper, I asked Dr Robert Brent, Distinguished Professor of paediatrics, radiology and pathology, Thomas Jefferson University, whether he has an information package to counsel exposed workers. Dr. Brent has counselled many thousands of patients, particularly pregnant women, on effect of radiation on the unborn, during his distinguished career over several decades. He contributed significantly to address the topic at the Health Physics Society Ask the Expert (HPS ATE) web site.

“We have many answers on the HPS ATE website that pertain to these questions, however, the anxiety level of the questioner is usually high and they want a personal answer to their questions and concerns.

Each exposure is different as are the circumstances; generic answers do not help these contacts.

They want the personal touch and that is what we give them. The risk of cancer from low exposures of radiation is very anxiety provoking and an erudite generic paragraph just does not solve the contact’s concern,” Dr Brent responded to an e-mail message. Counselling persons who were exposed to radiation is a challenging job. A specialist can do it competently if he uses all the resources available to him.

K.S.PARTHASARATHY

Former Secretary, AERB

( ksparth@yahoo.co.uk)

© Copyright 2000 - 2008 The Hindu

CT scanning: safety issues

The Committee on Medical Aspects of Radiation in the Environment (COMARE), UK, has just now published its report on the impact of personally initiated X-ray computed tomography (CT) scanning for the health assessment of asymptomatic individuals. Every one must be read this, as it is a scholarly assessment of a powerful medical imaging tool.




Science and technology Janaury 4, 2008, Chandigarh, India


CT scanning: safety issues
K.S. Parthasarathy

ON December 19, the Committee on Medical Aspects of Radiation in the Environment (COMARE), UK, published a report on the impact of personally initiated X-ray computed tomography (CT) scanning for the health assessment of asymptomatic individuals. Everyone must read this 83-page report (www.comare.org.uk/documents/COMARE12thReport.pdf) which comprehensively deals with the safety issues of CT scanning.

The report noted that in UK, some commercial CT services market CT scanning of the asymptomatic individual directly to the public as a form of preventative medicine to give individuals some peace of mind!

We are not far behind. Advertisements extolling the virtues of CT scanning have started appearing in India also.

CT scans promise greater diagnostic accuracy and an increased range of clinical applications; there is also the potential for greater radiation doses to individuals, from interventional techniques and from changes of practice within X-ray computed tomography (COMARE, 2007).

According to COMARE, a typical CT scan with an effective dose of 10 mSv is associated with a predicted average risk of fatal cancer induction of 1 in 2000 over a lifetime. (mSv is a unit of biologically effective radiation dose. A chest x-ray test exposes the patient to a dose of 0.02mSV)

The harm associated with a medically necessary CT scan is below that considered to be unacceptable, compared to the spontaneous fatal cancer risk of approximately 1 in 4.

“If 100,000 people undergo a CT scan every five years from age 40 to 70 years, receiving an effective dose of 10 mSv from each scan, then the estimated impact is approximately 240 excess fatalities…….. For scanning at higher frequencies (every two years or annually) this increases to 600 and 1200 fatalities, respectively.” COMARE cautioned.

The risk from repeated scans is unacceptable. Physicians must consider the use of alternative techniques using lower doses of ionising radiation or non-ionising radiation.

In any country, medical radiation exposure constitutes the major part of the radiation exposure from artificial sources of radiation. COMARE considered the detriment caused by radiation from the CT scan and also the subsequent psychological effects and potential physical detriment from further investigations.

Commercial CT services should provide comprehensive information regarding dose and risk of the CT scan, as well as rates of false negative and false positive findings. False negatives will lead to wrong feeling of good health, while tests that provide false positives may cause psychological trauma followed by more diagnostic tests.

The committee clarified that “it may not be possible to give an asymptomatic person a complete ‘all clear’ after a scan….It is also not clear whether CT imaging detects some cancers (eg lung) that are not as clinically as aggressive as those identified following presentation with symptoms”. Some cancers may be present at the individual’s death and would not have been life-threatening.

COMARE recommended that any individual displaying symptoms and requesting a CT scan from a commercial service should not be scanned and should be referred back to their physician.

The report considered in detail scanning of whole-body and three specific anatomical regions.

COMARE asserted that it is not possible to optimise exposure parameters for CT scans of the whole of the body. Services offering whole body CT scanning of asymptomatic individuals should discontinue to do so. CT should not be used to assess spinal conditions, body fat and osteoporosis in asymptomatic individuals (COMARE Press release, December 19)

COMARE concluded that there is no evidence that CT scanning for lung conditions is of benefit. However, cardiac CT scanning has been shown to have value for predicting cardiovascular risk and similarly CT colonography has the potential to detect small lesions. Both cardiac CT scanning and CT colonography should only be carried out in certain asymptomatic individuals.

The report recommended that CT scanning should only be undertaken on individuals with intermediate risk identified by a comprehensive cardiovascular risk assessment, unless the referral is by a cardiac specialist.

In view of the safety significance of CT scan units, they are subjected to licensing by the Atomic Energy Regulatory Board (AERB). It is illegal to operate a CT scan unit in India without obtaining a licence issued by AERB

Dr K.S. Parthasarathy is former Secretary, AERB

Nuclear news who is minding the shop

DAILY EXCELSIOR Julty 12, 2007 (PTI feature)

‘Nuclear’ news : Who is minding the shop ?

By Dr K S Parthasarathy

Recent controversies surrounding the visit of USS Nimitz, a nuclear aircraft carrier to Chennai, initially gave the false impression that there is no one to mind the shop!

Public had legitimate reasons to worry. The reassuring and prompt statements from scientists who knew the safety features of the reactors on board such ships and the lucid press release from the Ministry of Defence (MOD) allayed these fears to a great extent.

MOD had evolved the process of clearing the harbour for berthing nuclear vessels since January 5, 1988 when Indian navy inducted the nuclear powered INS Chakra into its fleet. The procedures included survey by an Environmental Survey Committee (ESC) set up by the Scientific Advisor to Defence Minister. MOD drew up a Radiation Safety Contingency Plan and implemented it prior to berthing of INS Chakra; the ship operated from 1988 to 1991.

From 15 February 2001 to 3rd November 2006, three nuclear powered ships from USA, three from France and one ship from UK visited India. There were ten visits; nine were to Goa and one to Mumbai. Indian Navy conducted the ‘International Fleet Review’ during which the French Nuclear Submarine Perle berthed in Mumbai harbour from 15 to 20 February 2001.

MOD intimates the ESC of an impending visit by a nuclear powered ship or submarine. ESC proceeds to the port well in advance before the arrival of the nuclear powered vessel and carries out a survey.

Movement of the nuclear powered ship takes place only during daylight hours, in good visibility and with escort tugs in attendance. No other ship is berthed within 200 metre radius of the nuclear powered ship. Ships berthed within 600 metre of the berth are kept at short notice, not exceeding tour hours, to get underway.

Radiation monitoring laboratories manned by scientists from Defence Research and Development Organization (DRDO)/Bhabha Atomic Research Centre (BARC) and Defence personnel, set up onboard a suitable ship, undertake frequent monitoring of water and air samples.

A standing ESC has carried out a detailed survey at Chennai and cleared the visit of USS Nimitz from radiation hazard point of view. The stingent radiation monitoring protocol in place includes periodic monitoring protocol in place includes periodic monitoring and analysis of air and water samples. The agency conducts these activities under the ambit of a well rehearsed Radiation Safety Contingency Plan over seen by a Crisis Management Group and a Crisis Management Cell comprising of scientists from DRDO, BARC, Defence Laboratory, Jodhpur, representatives of the Chennai Port Trust and the Indian Navy.

In spite of the well established and frequently rehearsed procedures in place, the visit of the carrier generated some controversy. Nobody discussed the issues so far though nuclear powered ships have been visiting Indian ports periodically. It is amusing to note that even as late as July 2nd this year news agencies continue to state that USS Nimitz is the first nuclear powered ship to visit an Indian port though the press release dated July 27 from MOD gave details of ten visits during 2001-2006. Our scientists and engineers have been operating nuclear facilities including several nuclear power reactors for the past many decades, a few of these are based at coastal areas. Scientists in the Environmental Survey Laboratories have developed state of the art capability to measure radioactivity in samples of air and water from the sixties.

Plant, site and offsite emergency plans are in place at every nuclear power plant. Preparing relevant documentation and enforcing appropriate plans with the help of scientists and engineers are routine functions for the concerned authorities.

In April 1994, a ‘‘scientist’’ working with an NGO reported that his team measured high levels of radiation in several parts of Lucknow, including MLA's hostel and a few posh areas. Many national dailies and local Doordarshan covered the news.

Three scientists from the Atomic Energy Regulatory Board (AERB) and the Bhabha Atomic Research Centre (BARC) investigated the observations and unambiguously demonstrated that the reported increase in background radiation was due to a deficiency of the instrument. It was sensitive to light and indicated some spurious reading when its detector was exposed directly to sunlight with its window open.

The team measured radiation levels in the locations referred to in the NGO's press release and observed that they were within the range normally expected in that part of the country arising solely from natural background radiation.

AERB publicized the findings of the committee. Though the ‘scientist’’ working with the NGO accepted the conclusions of the committee on the spot, he repeated his claim later and said that he was confident he would ‘‘come out with clinching evidence’’ at an appropriate time.

In September 1994 a report from Washington stated that Pakistan was within hours of sending American supplied F-16 jets on a mission to drop conventional bombs on the nuclear reactors at Trombay. ‘‘Millions of people would have died and it would have been a holocaust beyond anything...had Pakistan attacked the two research atomic reactors, Dhruva and Cirus’’, the report warned.

In response to a senior journalist from a national news agency, I explained the topography of Trombay and the design features of the reactors. I explained that a nuclear facility may have plant, site and offsite emergency plans as appropriate. Detailed analysis has shown that releases, if any, from the reactors at Trombay even in an extreme emergency will not have any offsite impact. I told the journalist that the statement from Washington is ‘most absurd’. The item got wide media coverage and hopefully allayed some fear.

Nuclear and associated community must realize that, often, radiation or nuclear safety matters raise alarm totally disproportionate with any measurable harm. They must address these concerns promptly, honestly and openly. It is at times wiser to be proactive. Media is always receptive to those who are minding the shop !

PTI Feature

Architects of nuclear India

Close collaboration between Dr Homi Bhbabha and Pandit Jawaharlal Nehru helped to lay the foundations of nuclear India. Both of them can be considered as the architects of nuclear India
K.S.Parthasarathy

Daily Excelsior
November 27, 2007
(A PTI Feature)
Architects of Nuclear India
By K S Parthasarathy
We celebrated the 97th birth anniversary of Dr Homi Bhabha on October 30, 2007. Pandit Jawaharlal Nehru's 118th birth anniversary was on November 14, 2007. Nehru helped to translate Bhabha's dreams into reality. They were truly the architects of nuclear India.
On January 4, 1947, while laying the foundation stone of the National Physical Laboratory at New Delhi Pandit Jawaharlal Nehru spoke thus on the necessary of atomic research in India : ‘‘... I do not see how we can lag behind in this very important matter, because atomic energy is going to play a vast and dominant part, I suppose, in the future shape of things... it will make power mobile and this mobility of power can make industry develop anywhere. We will not be tied up by accidents of geography....’’
Dr Bhabha's note on the organisation of atomic research in India submitted to Nehru on April 26, 1948, showed amazingly similar views.
‘‘The report submitted to you, Mr Prime Minister, on my return from Europe and America collected evidence which made it reasonable to believe that within the next couple of decades atomic energy would play an important part in the economy and the industry of countries and that, if India did not wish to fall even further behind industrially advanced countries of the world, it would be necessary to take more energetic measures to develop this branch of science and appropriate larger sums for the purpose.’’
‘‘.. our immediate programme should include extensive and intense search for sources of uranium. These geological surveys would take at least two years if carried out in any careful and exhaustive way and it is possible that their result may be negative. In that case, India would either have to depend on an agreement with a foreign power for the purchase of her uranium... ‘‘Bhabha pleaded. The search continues !
On the first International Conference on the Peaceful Uses of Atomic Energy at Vienna he wrote: ‘‘... What is so gratifying is the cordial atmosphere in which all the... discussions were carried out, entirely free from political bias or cold war hostility. Besides the regular sessions, a number of informal meetings were held among scientists including those from the so called iron curtain countries, at which scientific problems were discussed fully and freely’’. He knew that such ambience at the Geneva conference would be of special interest to his mentor.
By then, the Bandung Conference of Afro-Asian countries was over. Nehru was shortly destined to play the role of the leader of the Non Alignment Movement.
Occasionally, Bhabha led wars to defend his turf. He wanted to keep the construction of the Canada Indian Reactor, a highly technical project, exclusively with the Department of Atomic Energy (DAE). As the project was started strictly outside the Colombo Plan, he argued that there is clearly no advantage in routing related correspondence through the Department of Economic Affairs. ‘‘Indeed it will slow down the entire process’’ he cautioned. Nehru concurred.
Bhabha obtained exemption from certain Government regulations by writing to Nehru who always endorsed his decisions. These include provision of cars at the disposal of scientists during the commissioning of Apsara reactor and supply lunch and dinner at the work site at Trombay.
Bhabha deftly drafted the resolution settting up the Atomic Energy Commission (AEC). He set up AEC, as an organisation ‘‘with full authority to plan and implement the various measures on sound technical and economic principles and free from all non-essential restrictions or needlessly inelastic rules’’.
‘‘The special requirements of atomic energy, the newness of the field, the strategic nature of its activities and its international and political significance have to be borne in mind in devising such an organization’’, the resolution stipulated. AEC has the powers of the Government of India in all its Ministries, in so far as the work of the Department of Atomic Energy is concerned.
Dr Bhabha managed to set up the Secretariat of the Department of Atomic Energy (DAE) at Bombay and not in Delhi. The Department secured exemption from all reference of its civil engineering and construction work to the Central Public Works Department and of its purchase from the Directorate General of Supplies and Disposals. Similarly DAE follows its own procedures to recruit its staff and need not approach the Union Public Service Commission. Bhabha could secure the support of the highest echelons of the bureaucracy because of his rapport with Panditji.
Nehru's letter to ‘‘My Dear Homi’’ written on July 29, 1956 revealed that there was no barrier between these leaders. While discussing the composition of delegates of an International Conference at Vienna, Nehru cautioned, ‘‘I find that some of the other major countries are sending non-technical people as leaders of their delegations. It would probably be advisable for you and your scientific colleagues not to get mixed up too much with the political aspects.’’
While referring to the need to develop scientific temper, Nehru was brutally objective.
He did not spare even scientists. ‘‘--I do not mean that even now our big scientists are really scientific in mind, which I find often they are not. They are scientific in their laboratories; take them outside these and they appear to be frail human beings...’’
After staying in Cambridge for two days in June 1959 to receive an honorary degree of Doctor of Science, Bhabha wrote, ‘‘My dear Bhai, this was evidently a particularly good year for roses. I have never seen such profusion of beautiful roses as was to be found... at the back adjoining the river’’.....
....‘‘I hope some of the scientific laboratories and establishments we are building today will have the beauty of their own, which will have its due effect on those who work here.
I think both Trombay and the Tata Institute of Fundamental Research will be architecturally, and botanically beautiful when they are completed..’’ He eloquently articulated his vision.
Nehru must have acknowledged Homi's sentiments by looking blissfully at the red rose on his jacket !
(PTI) .

The first report on how India achieves nuclear safety

The article is a summary of the first National report for the Convention on Nuclear Safety submitted by India in September 2007 to the fourth Review Meeting of Contracting parties to be held in April 2008

K.S.Parthasarathy





Date:13/12/2007 URL: http://www.thehindu.com/thehindu/seta/2007/12/13/stories/2007121350101500.htm Sci Tech



The first report on how India achieves nuclear safety

It lists important safety improvements at each power station, starting with Tarapur

The average capacity factor for the Indian nuclear reactors for 2005-06 was 74 per cent

Among other measures, reduction of radiation doses to workers is notable

Recent debates on the Indo-US agreement for cooperation concerning the peaceful use of nuclear energy compelled the media to look at nuclear power more benignly. Members of the public realised for the first time that nuclear power has a role to play in the energy mix of the country. Those who have concerns on nuclear safety, must read the first ‘National Report for the Convention on Nuclear Safety (September 2007),’ to find out how India achieves nuclear safety . (Please see www.aerb.gov.in or www.dae.gov.in for the text of the report.)

Measures explained

The 208 page report explains the measures taken by India to implement the Convention on Nuclear Safety, the first international legal instrument dealing directly with the safety of civilian nuclear power plants. The Fourth Review Meeting of the Contracting Parties scheduled to be held in April 2008 will examine the report along with 13 others including those from Canada, France, Russia and U.S. The international peer review is unique to the nuclear industry.

The report highlights the steps taken to implement Articles 6 to 19 (Chapter 2 titled ‘Obligations’). It lists important safety improvements at each power station starting with the Tarapur Atomic Power Station (TAPS) which began its operation in 1969. The comprehensive safety review and implementation of safety up-gradations for continued operation of TAPS-1 and 2 are notable.

The report gives graphically the electrical power generated by each reactor in India and its availability and capacity factors. Nuclear Power Corporation of India Limited (NPCIL) deserves congratulations for consistent performance for the past few years.

The average capacity factor for the Indian nuclear power reactors for 2005-06 was 74 per cent. India must compete with other countries now. The U.S. recorded an average capacity factor of 89.6 per cent in 2006 for 105 reactors with 29 reactors exceeding 95 per cent. The comprehensive safety assessments carried out after major events such as the accident at Three Mile Island in the U.S. and that at Chernobyl in the former Soviet Union are very informative. NPCIL implemented the recommendations arising from these assessments.

Following the pressure tube failure incident at the Pickring-2 reactor in Canada, India introduced a major programme to ensure the integrity of the pressure tubes in Indian Pressurized Heavy Water Reactors by enhancing the design as well as in-service-inspection and rehabilitation technologies.

The thoroughness with which AERB reviewed the fire incident at Narora in March 1993 and the tsunami incident at Kalpakkam in December 2004 and ensured implementation of its recommendations is reassuring.

Seismic re-evaluation of old generation reactors, enhanced inspection of certain systems and components, ageing management and reduction of radiation doses to workers are notable.

The directive prescribing ‘formal and elaborate retraining and re-licensing of all the frontline operating staff and the station management personnel’ following a safety-related incident at the Kakrapar Atomic Power Station reflects the no-nonsense attitude of AERB

The report describes the legislative and regulatory framework including the Atomic Energy Act 1962 and the rules framed under it and other legal instruments such as Indian Electricity Act 2003, Environment (Protection) Act 1986 etc.

It highlights the functions and responsibilities of AERB, the Board’s organisational structure and its position in the government which ensures administrative and financial independence in its functioning.
Forum member

AERB participates in the activities of the International Atomic Energy Agency (IAEA).

It is a member of the forum for the CANDU senior regulators with six other countries operating pressurized heavy water reactors. AERB and the US Nuclear Regulatory Commission have held several meetings on safety related topics.

The Board has a cooperation agreement with the French Directorate General of Nuclear Safety and Radiation Protection and the Federal Nuclear and Radiation Safety Authority of Russia.

The measures India takes to comply with other Articles covering the responsibilities of the licensee, financial and human resources, capabilities and limitations of human performance, quality assurance, assessment and verification of safety, radiation protection, siting, design and construction and emergency preparedness are very comprehensive.
Acronyms, jargon

The report contains some tongue-twisting acronyms and incomprehensible jargon (defendable as the report is meant for scientists and engineers!); it also contains a wealth of useful information patiently collected, collated and interpreted from government documents, incident reports, minutes of meetings and publications.

The feedback from the review meetings will help to enhance nuclear safety in countries operating nuclear power plants.

K.S.PARTHASARATHY

Former Secretary, AERB

( ksparth@yahoo.co.uk )

© Copyright 2000 - 2007 The Hindu

Do cancers soar with CT scans?

Recently Drs David Brenner and Eric Hall claimed that about 1.5 to 2 % of cancers in USA are caused by CT scans. The paper was published by the NEJM on Novemeber 29, 2007.Profesional associations such as the American College of Radiology (ACR), the American Association of Physicists in Medicine (AAPM) and the Radiological Society of North America (RSNA) published critiques on the paper.

Mostly they felt that the conclusions in the paper can create a scare in the minds of public and keep them away from much needed medical procedures. My paper in the Science & Technology issue of the Hindu states that in spite of the controversies, there are many key points of agreement among all.CT Scan is a very useful imaging modality in medically indicated examinations.

Specialist agencies across the board fear that the public may not understand complex scientific arguments. They tend to forget the fact that physicians face the challenge every day. The public will resolve the issues if specialists give all the inputs.

K.S.Parthasarathy




Do cancers soar with CT scans?

Most CT scans result in limited exposure
Benefits from CT scans are not without risks



Useful tool: CT scans are immensely useful in diagnosis and in the guidance of therapeutic procedures.


Recently, Drs David Brenner and Eric Hall, researchers in the Columbia University Medical Centre, New York contended that about 0.4 per cent of all cancers in the U.S. may be attributable to radiation from computed tomography (CT) studies.
They claimed that they used the most scientific radiation risk estimates, and the data on the use of CT from 1991 to 1996.
If current data are used, it may be as high as 1.5 to 2 per cent, they reported in the New England Journal of Medicine (NEJM, November 29, 2007).
Low level radiation
The American College of Radiology (ACR), the Radiological Society of North America (RSNA) and the American Association of Physicists in Medicine (AAPM) reacted to the NEJM paper with predictable alacrity. The effect of low level radiation on living beings continues to be controversial (The Hindu, July 14, 2005).
ACR declared that certain conclusions and comparisons made in the NEJM study may be inappropriate and cause patients to mistakenly avoid getting life-saving medical imaging care.
“Patients need accurate information on which to base their healthcare decisions. They may be terribly confused and unduly distressed by some of the statements in this study,” Dr Arl Van Moore Jr., chairman of the ACR Board of Chancellors cautioned.
“The Brenner article illuminates many issues of importance in regards to CT, but the CT experts in the AAPM feel that much of the message of this article may be misconstrued or misunderstood by the press or by the public who may not be experts in CT,” AAPM warned.
“Advancing technology has increasingly allowed imaging exams to replace more invasive techniques, but has also resulted in increased radiation exposure for Americans” ACR conceded.
ACR and AAPM faulted the study for equating the survivors of atomic bombings to patients undergoing CT scans.
“Most CT examinations are conducted under controlled conditions. They result in limited radiation exposure to a small portion of the body.
Atomic bomb survivors experienced instantaneous radiation exposure to the whole body,” ACR clarified. There were other differences. Brenner and Hall argued that survivors of atomic bombings who received doses similar to patients undergoing CT scans did suffer excess cancers.
AAPM wanted that patients should discuss with their physicians not only the radiation risks of the CT examination, but the risks of not having the diagnostic information that CT provides.
AAPM acknowledged that David Brenner and Eric Hall are esteemed scientists and respected experts in radiation risk and AAPM’s release is in no way meant to impeach or undermine their impressive credentials.
Radiologists, medical physicists and other radiology professionals have long recognised the need to implement CT practice conscientiously and maintain rigorous standards of practice (RSNA, 2007).
The NEJM study focussed attention on overuse of CT. One million children and 20 million adults in the U.S. undergo unnecessary CT scan procedures annually.
Some researchers believe that estimating the number of cancers at low radiation doses has no scientific basis. Others like Brenner and Hall disagree.
But all agree on some key points. CT scans are immensely useful in diagnosing diseases and trauma and in the guidance of interventional and therapeutic procedures.
Not risk free
However, these benefits are not without risks. The individual risk from X-rays associated with a CT scan is quite small, compared to the benefits of diagnosis in medically needed procedures.
It is important to keep the radiation doses during medical X-ray procedures as low as reasonably achievable.
Using CT for routine screening is unjustified (The Hindu, January, 5, 2006). Specialists do not recommend CT coronary angiography of asymptomatic patients for assessing occult coronary artery disease (The Hindu, November 2, 2006).
Physicians must make every effort to reduce radiation dose in CT procedures, especially for children (The Hindu, February 8, 2007). CT should not be used to screen persons for lung cancer (The Hindu, September 13, 2007).
Complex arguments
Specialist agencies across the board fear that the public may not understand complex scientific arguments.
Whether cancers soar with CT scans cannot be answered conclusively. Prudence demands caution in using this powerful medical imaging modality.
They tend to forget the fact that physicians face the challenge every day. The public will resolve the issues if specialists give all the inputs.
K.S. PARTHASARATHY
Former Secretary, AERB
( ksparth@yahoo.co.uk)
© Copyright 2000 - 2007 The Hindu

Will cockroaches emerge as survivors of a nuclear war?

Will cockroaches survive a nuclear war? Cockroaches alleged radiation resistence may be a myth.The Discovery Channel plans to test the myth.We will know the result four moths from now when the Channel will air its programme.

K.S.Parthasarathy



Date:01/11/2007 URL: http://www.thehindu.com/thehindu/seta/2007/11/01/
stories/2007110151122300.htm Sci Tech

Will cockroaches emerge as survivors of a nuclear war?

Everyone expects cockroaches to survive a nuclear war. If cockroaches are close to the ‘epicentre,’ they will be incinerated because of the intense heat. The legend is built on the notion that cockroaches are radiation resistant.

Safe testing

Recently, ‘myth-busters’ of the Discovery Channel decided to settle the issue once and for all. Kari Byron, the TV hostess, revealed that the radiation resistance of cockroaches was in their list of myths from day one.

The TV team had to convince the Discovery Channel that they can do the testing safely (Tri-city Herald, October 19, 2007). Kari Byron noted that people are just scared when they hear radiation. She attributes this to the availability of “too many zombie movies”.
Routine use

It appears that the Channel does not know that industry routinely uses hundreds of irradiators all over the world safely to expose thousands of samples of food, medicine and surgical products to precisely known radiation doses. Irradiating a few hundred roaches is no big deal! Byron’s team will expose 200 ‘farm fresh’ cockroaches, bought from a scientific supply company.
Different doses

The staff of Pacific Northwest National Laboratory will assist the TV team to expose the cockroaches to different doses of gamma radiation using an irradiator located in the basement of a building at Hanford.

A group of 50 cockroaches, left unexposed will serve as control. The second group of 50 will receive 1000 rads. The third and fourth groups of 50 will have to suffer doses of 10,000 rads and 100,000 rads respectively. (Rad is a unit of radiation dose; a dose of 450 rads may kill 50 per cent of the persons exposed).

To add insult to injury, the experimenters will confine the beasts to small boxes to ensure uniform doses to each group! They plan to expose flour beetles and fruit-flies to similar doses.

The team faces some logistic problems. The exposed insects must reach San Francisco for close observation.

They cannot fly them as airlines will not let them in the passenger cabin; they cannot be placed in the baggage hold without wrecking the experiment (PhySorg.com, 2007).
Final destination

Grant Imahara, electronics and radio-control specialist of the TV Channel revealed that they have to maintain reasonable temperature and humidity so that the cockroaches will not go into shock. A ‘mythbusters’ employee will drive them to the final destination in San Francisco.

Tri-city Herald quoted Michelle Johnson, a technical group manager of the national lab as saying that the show presents good examples of scientific method and encourages developing a questioning attitude.

Gamma irradiation

“I have been told that cockroaches are more resistant to radiation and in a world nuclear war, only the cockroaches would survive. But I have not seen any publication that discusses it with any credibility… I have irradiated cockroaches and constructed killing curves for them using gamma irradiation… my opinion is that insects in general would be relatively resistant to radiation compared to non-insects…” Joseph G. Kunkel, Professor of Biology, at the University of Massachusetts at Amherst, who maintains a cockroach home page, asserted.

The lives of insects revolve around their molting (periodical shedding and renewal of the outer skin) cycles. “During a molting cycle the cells of the insect divide usually only once.

“This is encoded in Dyar’s Rule, i.e. insects double their weight at each molt and thus their cells need to divide only once per molting cycle”, he wrote.

“Cells are most sensitive to radiation when they are dividing. Now if a typical cockroach molts at most once a week, its cells usually divide within a 48-hour period within that week...about 3/4 of the cockroaches would not have cells that are particularly radiation sensitive at any one time.

“If a killing radiation is endured by a cockroach and human population, then 3/4 of the cockroaches might survive while none of the humans might survive since our blood stem-cells and immune stem-cells are dividing all the time”, he clarified.

Four months from now, we may get an answer when Discovery Channel airs its show!

K.S. PARTHASARATHY

Former Secretary, AERB

ksparth@yahoo.co.uk

© Copyright 2000 - 2007 The Hindu

Behaviour of birds and worms at Chernobyl

Date:18/10/2007 URL: http://www.thehindu.com/thehindu/seta/2007/10/18/stories/
2007101850081500.htm
________________________________________
Sci Tech



Behaviour of birds and worms at Chernobyl
________________________________________
Lot of variation among species and within species
Strong correlation between internal dose, radiation level
________________________________________
Recent studies of birds at Chernobyl revealed some strange behaviour of certain species. Anders Moller at Pierre and Marie University in Paris and Tim Mousseau at the University of South Carolina found that the bird species, pied flycatcher and the great tit (Parus major), generally avoided nesting boxes kept at high levels of background radiation. Pied flycatcher exhibited stronger effect. Radiation levels at some nest sites were as much as 2,000 times the natural levels elsewhere in the world (New Scientist, March, 28, 2007).
Nest site choice
“Inter specific differences in effects of radiation on nest-site choice suggest that species respond in a species-specific manner to radiation,” they claimed (Proc. Roy.Soc. Biology, March 27, 2007).
Their claim may not be valid as they did not consider internal doses which were substantial. “We cannot agree more that internal dose is most important. We have…measured dose rate of over 300 birds around Chernobyl. There is a very strong correlation between internal dose and radiation level at the site of capture,” the authors responded. Ukrainian scientists coordinated the study of internal body burden estimates.
“… the preliminary results suggest considerable variation among species and individuals within species, even those living in the same general area. We hope to fully explore these data once our colleagues have finished with the primary publication,” Dr Mousseau clarified.
Once Time magazine noted that yellow legged mud-dauber wasps at the Oak Ridge National Laboratory use mud containing radioactivity to build their nests whereas pipe-organ mud-daubers use only non-radioactive mud, though the same source of nest materials was available to both ( http://www.time.com/time/printout/0,8816,897250,00.html).
Dr Mousseu had seen mud-dauber tubes at the Savannah River site. “I will investigate the possibility of measuring activity in the mud,” he promised in an e-mail message. He noted that barn swallows, the bird species studied extensively at Chernobyl also build their nest in the area!
Three species studied
Certain species of worms in the lakes in Chernobyl behaved strangely! Scientists studied three species contaminated by radioactivity from the Chernobyl accident; greater proportions of two species of worms started seeking partners for sex, switching from asexual to sexual reproduction. Ukrainian scientists believe that they did it to increase their chance of survival (EurekAlert, April 9, 2003).
The third species showed double the rate for asexual reproduction in the polluted lake (Journal of Env. Radioactivity, 2003).
Background radiation in certain areas of Kerala and Tamil Nadu is above normal (far too less than that in Chernobyl).
I asked Dr Mousseau whether the study of insects and other invertebrates in such high background radiation areas (HBRA) is of any interest.
“It would seem to me that this region would likely reveal some very interesting adaptations to radiation that might not have had time to evolve in other regions”, he conceded. “…it would be important to focus on a few key species that occur in this area and examine survival and reproduction with control sites.
Similarly, it would be valuable to examine the community of organisms, especially insects, to determine if species composition changes in a predictable way.
Either way, I suspect that this region would be an excellent target for further investigation and my suspicion is that one would be very likely to generate many exciting discoveries of organismal responses to this environmental effect”, he asserted.
No scientific basis
Learned national academies and international agencies should support a dedicated research project to study the flora and fauna in the HBRA.
Radiation biologists, geneticists, biotechnologists and radiation physicists must carry it out.
The International Commission on Radiological Protection has realised that its old concept that if man is protected, other organisms will be protected has no scientific basis.
K. S. PARTHASARATHY
FORMER SECRETARY, AERB
( ksparth@yahoo.co.uk)
© Copyright 2000 - 2007 The Hindu

Prettiest birds the hardest hit in Chernobyl

Date:04/10/2007 URL: http://www.thehindu.com/thehindu/seta/

2007/10/04/stories/2007100450091500.htm
________________________________________
Sci Tech



Prettiest birds the hardest hit at Chernobyl
Birds with bright, colourful plumage registered the strongest decline
________________________________________
Radiation produces free radicals which damage DNA and other molecules permanently
Four groups of birds which suffered most had high expenditure of antioxidants
________________________________________
At 01:23 hrs on 26 April 1986, the severest nuclear accident occurred at the Chernobyl Nuclear Power Station in Ukraine. Radioactive materials from the stricken reactor got released over the next ten days. Large areas got heavily contaminated. Initially, vast tracts of pine forests close to the site perished. Over the next few years, the lands recovered their green cover.
Recent reports claimed that animals like wild boar, wolves and moose had flourished in the 40 mile diameter exclusion zone (The New York Times, August 28, 2007).
‘Defying predictions’
“Contrary to the myths and imagery, Chernobyl’s land had become a unique, new ecosystem. Defying the gloomiest predictions, it had come back to life as Europe’s largest nature sanctuary, teeming with wildlife”. Mary Mycio who visited Chernobyl in 1996 described “the lands extraordinary resurrection” in ‘Wormwood Forest, A Natural History of Chernobyl.’
However, Dr. A.P. Moller and Dr T.A. Mousseau who carried out scientific studies of birds noted that population of the prettiest birds with bright, colourful plumage registered the strongest decline with radiation (Journal of Applied Eco logy, July 11, 2007). Population density of species of birds with long distance migration and dispersal and large eggs also declined with radiation level.
“Species richness, abundance and population density of breeding birds decreased with increasing levels of radiation even after controlling statistically for the effects of potentially confounding factors such as soil type, habitat, and height of vegetation” the researchers observed (Biology letters, August 14, 2007).
The researchers used point count census of 57 species of birds at 254 locations in the forests around Chernobyl to establish the relationship between abundance of birds and radiation levels.
Scavengers
Radiation produces free radicals which damage DNA and other molecules in living cells permanently. Antioxidants are free radical scavengers. They protect tissues against radiation damage.
Moller and Mousseau suggested that if antioxidants are a limited resource in the body, individuals with a high expenditure of antioxidants may suffer most from radiation. Pretty birds spent large amounts of carotenoids (these are antioxidants) in their colourful plumes, losing them irrecoverably.
Physical activity
Birds that migrate over large distances spent large amounts of antioxidants during their extreme physical activity. Birds which lay large eggs have lower levels of antioxidants as they deposit most of it in their eggs.
The researchers argued that the four groups of birds which suffered most had high expenditure of antioxidants (Journal of applied Ecology, 2007).
Important implications
“While the present study has implications for the study of animals living in radioactively contaminated areas such as Chernobyl… it may also have important implications for animals elsewhere. There is large variation in natural levels of radioactivity as a result of variation in abundance of radioactive isotopes…There are no studies of the biological consequences of such variations in natural levels of radioactivity, but we suggest that some of the consequences can be predicted from the present study”, the authors claimed.
The researchers expected that individuals of bird species with carotenoid-based plumage to have paler plumage colour in Chernobyl than individuals from control sites.
Similarly, we may expect that ladybird which has the highest number of carotenoids among insects may have paler hues in the high natural background radiation areas (HBRA) of Kerala. The radiation levels in HBRA are relatively low compared to those in Chernobyl.
Lesser range
But ladybirds in HBRA may get exposed to significant radiation doses as they have less range and may be considered to be relatively immobile compared to birds!
Any insect lover can test the hypothesis by carrying out a survey in HBRA for a few days!
Ladybirds may be radiation resistant. Scientists sent C.elgans, a type of round worm, which has been genetically mapped, in the stricken shuttle Columbia to study space radiation effects.
They survived the disaster. Cousins of these survivors may be present in HBRA!
K.S. PARTHASARATHY
Former Secretary, AERB ( ksparth@yahoo.co.uk)
© Copyright 2000 - 2007 The Hindu

Fungi that live off radiation at Chernobyl

Fungi that live off radiation at Chernobyl

It was shown how ionising radiation encourages growth of melanised fungi

Like chlorophyll, melanin uses a part of the electromagnetic spectrum to benefit the fungi

The phenomenon may be useful to astronauts, who may harvest the fungi as a food source

Occasionally, the lowliest of the lowly beings get global attention by being at the most unexpected places.

This was what happened to some microorganisms including Cladosporium sphaerospermum (CS). This tongue-twisting name belongs to a type of humble fungus.

Five years ago, Dr. Arturo Casadevall, Albert Einstein College of Medicine, New York, U.S., read in the web that a robot sent into the still highly radioactive damaged reactor at the Chernobyl nuclear power station, returned with samples of black fungi, which were growing on the reactor’s walls. (PhysOrg.com, May 23, 2007).
Habits revealed

It appeared that these fungi were feeding on radiation. They can no longer keep their radiation feasting habits away from the prying eyes of researchers.

These fungi contain melanin, a high molecular weight pigment, the same colouring agent in our skin.

Until now, the biological role of melanin has been a mystery (PHYSICS.ORG, 2007). In a 13-page paper in the Public Library of Science Journal (PLoS ONE, May 23, 2007) Dr Casadevall and other researchers explained the physico-chemical tests and in vivo experiments with three genetically diverse fungi and four measures of cell growth; they demonstrated lucidly how ionising radiation brings about changes in melanin and encourages the growth of melanised fungi.

An elegant and simple hypothesis may explain the behaviour of melanised fungi.

“Just as the pigment chlorophyll converts sunlight into chemical energy that allows green plants to live and grow, our research suggests that melanin uses a different part of the electromagnetic spectrum to benefit the fungi containing it”, Dr Ekaterina Dadachova, one of the co-authors of the paper, explained.
Providing energy

Dr Casadevall admitted that it is pure speculation but not outside the realm of possibility that melanin could be providing energy to skin cells. They grew some melanised fungi and others without the pigment and exposed them to gamma radiation.

The dark fungi grew better when irradiated (The New Zealand Herald May 27, 2007).

Certain types of fungi grew significantly faster when scientists exposed them to ionising radiation levels nearly 500 times more than the background; they gained more dry weight biomass.

People despise fungi because they assume that the main job of fungi is to decompose matter into other chemicals!

The melanin-containing microorganisms are often the dominating species in certain extreme environments (PLoS ONE 2007) such as the abandoned contaminated regions at Unit 4, the stricken reactor at Chernobyl.
Living happily

They live happily in soil contaminated with radionuclides, at high altitudes and in hostile Arctic and Antarctic regions!

There are indications that melanins are ancient pigments that have probably been selected as they enhance the survival of melanised fungi in diverse environments and, perhaps incidentally in many hosts (PLoS ONE, 2007).

Casadevall and his co-workers believe that despite the high prevalence of melanotic microorganisms in radioactive environments, it is unlikely that they synthesise melanin for the purposes of protection (shielding) from ionising radiation.

They noted that in the high altitude regions inhabited by melanotic fungi, the background radiation levels are about 500-1,000 times higher than at sea level.

Since most fungi, whether melanised or not, can withstand 17,000 times more energy, the authors consider that there is apparently no need for melanin to remain as a radio-protective agent.

But biological pigments play a major role in photosynthesis; they convert light energy to chemical energy.
Properties changed

Since melanin can absorb visible and UV light of all wavelengths, the authors suggested that exposure to ionising radiation would change the properties of melanin and affect the growth of melanized microorganisms.

They could convincingly demonstrate their expectations. The capability of fungi to live off radiation and make biomass may be useful to astronauts, who may be able to harvest the fungi as a food source.

The fungi can produce food by using enhanced levels of ionising radiation present in outer space.
Nature’s capriciousness

Nature is very capricious in revealing its resourcefulness. Lowly beings such as fungi can teach enterprising humanity a lesson or two in harnessing energy while surviving in unendurable environments.

K.S. PARTHASARATHY

Former Secretary, AERB
ksparth@yahoo.co.uk

© Copyright 2000 - 2007 The Hindu

Routine use of CT to screen for lung cancer risky

Routine use of CT to screen for lung cancer risky

Routine use of this unique tool on symptomless individuals is potentially hazardous

Photo: K.R. Deepak



Need for caution: Population based screening for lung cancer is not recommended and may, ultimately put the patient at risk for further complications. — .

The American College of Chest Physicians (ACCP) oppose the use of low dose computed tomography (CT) for general screening of lung cancer (EurekAlert, September 10).One hundred multi-disciplinary panel members developed and published the new evidence-based guidelines in a supplement to the September issue of CHEST, ACCP’s peer reviewed journal.

Mortality unaffected

Dr. W. Michael Alberts, Chief Medical Officer, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, cautioned that even in high risk populations, currently available research data do not show that lung cancer screening alters mortality outcomes.

“Population [based] screening for lung cancer is not recommended and may, ultimately, put the patient at risk for further complications,” said Dr.Gene L. Colice, Director, Pulmonary, Critical Care and Respiratory Services, Washington Hospital Center, Washington DC and vice chairman of the ACCP lung cancer guidelines.

He clarified that during screening, physicians may commonly find nodules; however, to determine whether they are cancerous or not requires fairly invasive and extensive additional testing. The patient may have to face needless risk, both physically and psychologically.

‘Diagnosis and Management of Lung Cancer: ACCP Evidence-Based Clinical Practice Guidelines (2nd Edition)’ contains 260 of the most comprehensive recommendations related to lung cancer prevention, screening, diagnosis, staging, and medical and surgical treatments. Some of these apply to computed tomography screening.

“There is little evidence to show that lung cancer screening impacts mortality in patients, including those who are considered at high risk for the disease” an ACCP press release asserted.

CT screening of symptom-free individuals is controversial. Peter B. Bach and his co-workers analysed lung cancers in 3,246 asymptomatic current or former smokers screened for lung cancer from two academic centres in the U.S. and one in Italy and found that screening for lung cancer with low dose CT may increase the rate of lung cancer diagnosis and treatment, but may not meaningfully reduce the risk of advanced lung cancer or deaths from lung cancer (JAMA, March, 7).

They argued that until more conclusive data are available, asymptomatic individuals should not be screened outside clinical research studies that have a reasonable likelihood of further clarifying the potential benefits and risks.
Conclusions opposed

These results contradict the conclusions of the International Early Action Lung Cancer Programme, which claimed that CT screening of high risk individuals could prevent 80 per cent of lung cancer deaths (New England Journal of Medicine, 2006).

After reviewing these two papers, Drs William C. Black and John A. Baron concluded thus: “Although expensive and time consuming, rigorous trials for cancer screening are far more cost-effective than what might be the alternative — widespread adoption of costly screening interventions that cause more harm than good” (JAMA, March, 7, 2007).

The unambiguous ACCP guidelines must settle the issue. The ACCP Thoracic Oncology NetWork, the Health and Science Policy Committee, the Board of Regents, and external reviewers from the journal CHEST reviewed and approved these guidelines.

The American Association for Bronchology, American Association for Thoracic Surgery, American College of Surgeons Oncology Group, American Society for Therapeutic Radiology and Oncology, Asian Pacific Society of Respirology, Oncology Nurses Society, Society of Thoracic Surgeons, and the World Association of Bronchology also endorsed them.

Over 2,200 CT scan units are used in India. These are beneficial tools only in clinically indicated diagnostic tests.

Each CT scan exposes patients to radiation doses equal to a few hundreds of chest x-ray examinations. Routine use of this unique tool on symptomless individuals is potentially hazardous.
Panel of specialists

Professional associations in India must develop robust guidelines. In the absence of such efforts, the Health Ministry must urgently set up a panel of specialists with representatives from Indian Council of Medical Research, the Atomic Energy Regulatory Board and professional associations to review the ACCP recommendations and other similar guidelines.

The panel may be asked to examine the applicability of these guidelines in the Indian context and make appropriate recommendations.

K.S. PARTHASARATHY

Former Secretary, AERB
( ksparth@yahoo.co.uk)

© Copyright 2000 - 2006 The Hindu

Safety factors considered in nuclear powerplant location

Safety factors considered in nuclear power plant location

A detailed analysis revealed that a postulated fault at Kalpakkam did not exist

The AERB Code of Practice on Safety in Nuclear Power Plant Siting prescribes 48 criteria

The doses to public due to radioactive releases during normal operation are within AERB limits

While addressing a public meeting organised by the Rotary club in a metro city, one of the speakers asked the audience whether they prefer to have a cattle farm or a nuclear power plant in their backyard.

The voice vote clearly favoured a cattle farm! The reasons for the “Not In My Backyard (NIMBY) view” are not far to seek. Public distrusts nuclear industry.
Previous accidents

The accidents at the nuclear power station at Three Mile Island in the U.S. in 1979 and that at the Chernobyl nuclear power Station in Ukraine in the former Soviet Union in 1986 did not help.

The discerning public may blame the nuclear establishment, if the NIMBY attitude continues. NIMBY will become In My Backyard (IMBY), if the public realises the steps taken to ensure safety in nuclear power plants.

These include the choice of the right site; construction of reactors of proven technology; institution of sound quality assurance measures; provision of diverse and redundant reactor control and protection systems of high reliability; defence-in-depth philosophy; proven operating procedures by qualified and trained staff; continuous review and feedback of operating experience; well rehearsed emergency prepared plans among others.

The AERB (Atomic Energy Regulatory Board) Code of Practice on Safety in Nuclear Power Plant Siting prescribes 48 criteria; thirty of them are mandatory; seven are desirable. Eleven criteria belong to the rejection category.

The AERB reviews the effect of natural events such as earthquakes, winds, floods, tides, slope instability, etc and man-induced events such as air-crash, oil slick, blasting, mining etc. on the plant.
Outright rejection

A few seismic criteria prescribe outright rejection of certain sites. Other factors include prescribed grade elevation above tide level, location of airfields, military installations storing ammunition, architectural or historical monuments and pilgrimage or tourist centres. Sites will be acceptable only if they satisfy AERB Codal requirements.

The desirable parameters specified by AERB Code include distance from the site to the facilities, if any, handling/storing inflammable, toxic, corrosive or explosive material and any mining activities, the terrain features and the population density within specified distances.

A site selection committee of specialists appointed by the Central Government chooses the sites for locating nuclear power plants from the sites proposed by the State Governments.

AERB issues siting clearances valid for a specific period after reviewing the recommendations of its Site Evaluation Committee (SEC) and a senior level Advisory Committee for Project Safety Review (ACPSR).

Recently, the SEC recommended installation and operation of a five-station micro earthquake monitoring network at the Prototype Fast Breeder Reactor (PFBR). It is operational now. AERB recommended a detailed analysis and field check to ascertain the status of a postulated fault at Kalpakkam.
Coastline stable

The study revealed that the fault does not exist. On the recommendation of SEC, National Institute of Oceanography (NIO) studied the shore line stability at Kalpakkam. NIO found that the coastline was stable. A detailed study for evaluation of tsunami hazard in Kalpakkam area is in progress.

Nuclear power reactors produce large amounts of radioactivity during their operation.
Design features

Design features and safety measures ensure that the radiation doses to workers are well within the limits prescribed by the AERB. AERB may argue that there is scope for reduction.

The doses to public due to radioactive releases during normal operation are too low to be measured directly and are within AERB limits.

They are within the variations of the natural background radiation present everywhere even in the absence of nuclear power plants. The safety performance of Indian reactors is reassuring.
Recent survey

A recent survey in the U.S. organised by the Nuclear Energy Institute, a nuclear advocacy group, among 1,100 adults, revealed that 71 per cent would be willing to see a new reactor near them (World Nuclear News, August 21), a probab le response in France, as it generates 78 per cent of its electricity from nuclear reactors.

The French are very proud of their nuclear programme. If the recent awareness on nuclear issues is an indication, NIMBY attitude among the Indian public will hopefully turn into IMBY during the next few years!

K.S.PARTHASARATHY

Former Secretary, AERB
ksparth@yahoo.co.uk

© Copyright 2000 - 2006 The Hindu