K.S.Parthasarathy
April 17, 2008
Radiation epidemiological studies near nuclear facilities
There is evidence that the cancer rates in population groups exposed to high doses of radiation will be relatively high. But the evidence at low doses is controversial. A few specialists believe that low dose radiation is beneficial to man (the Hindu, September 29, 2005)!
The limitations
Many specialists want to know whether very low levels of radiation caused by permitted radioactive releases from nuclear power plants, uranium mines, mills etc can cause excess cancers in man or not.
They do not appreciate the limitations of epidemiology. They believe that they can get a deterministic answer to a purely probabilistic question! That too using a statistically weak study.
“…. there is often a tendency to carry out epidemiological studies concerning the induction of cancer in radiation workers and members of the public which are not supported by a statistically valid data base or whose result are misinterpreted or misused”. Drs Joan M. Davies and Hazel Inskip eminent epidemiologists wrote in the foreword to their book on the topic. (Davies and Inskip, 1986)
A paper titled “Meta- analysis of standardized incidence and mortality rates of childhood leukaemia in proximity to nuclear facilities by Baker and Hoel in the European Journal of Cancer Care (2007) illustrates the dilemma...
The authors reviewed studies from one hundred and thirty six sites in nine countries.
Although the analysis showed consistently elevated rates of leukaemia, the authors of such papers found that radiation dose due to environmental discharges from the facilities are too low to account for the excess cases.
In several studies, the leukaemia death rates remained unchanged before and after start up even in regions with elevated rates!
Low excess risk
A study at 62 sites in USA, revealed leukaemia death rates to be higher before start up of the nuclear facility when compared with those after start up. Some authors found excess leukaemia in regions where nuclear facilities were expected to come!
In these studies, no one brought out one point; excess risk, if any, is extremely low and zero risk cannot be rules out.
Recently, a section of the media published reports on a study by the Indian Doctors for Peace and Development (IDPD) claiming adverse health effects in villages within the radius of 2.5 km from the uranium mine in Jadugoda. Their conclusions remain unsubstantiated. (Unsubstantiated till published in a peer reviewed journal).
Bypassing peer review
The authors presented their “study” at a conference on “Nuclear Weapons: The Final Pandemic Preventing Proliferation and Achieving Abolition” during October 3-4, 2007 at London.
Peer review
They successfully circumvented the traditional scientific peer review and publication process by using the media. Only vigilant journalists can arrest this lamentable trend. The full paper which the organisers of the London Conference sent me showed how "cherry picking" can masquerade as epidemiology. At the very outset, the authors stated thus: “We assumed that specific health problems related to uranium mining was affecting the indigenous people disproportionately in the study villages compared to the reference villages”.
Questionnaire
Then they searched for evidence to support the assumption! “A structured questionnaire was developed…. and was introduced on the heads of families of each house hold by a team of investigators.
The investigators, 34 in number, were men and women from the vicinity of Jadugoda”. Their areas were carpet –bombed with weird stories on uranium hazards for the past few years!
Brazen admission
“ Responses to some of the variables in few of the interview schedules were not found to be satisfactory and such responses were not considered for data analysis” the authors brazenly admitted to “cherry picking” of the data. None of the medical committees of qualified specialists, which surveyed Jadugoda villages found any disease which could be related to radiation exposure. Based on media reports and other documents an advocate filed a Public Interest Litigation (No 188 of 1999) in the Supreme Court of India seeking judicial intervention to have the necessary steps taken to safeguard the health of the population.
“In view of the affidavit filed by respondent No 3-Chairman, Atomic Energy Commission, that adequate steps have been taken to check and control the radiation arising out of uranium waste, we do not find any merit in the petition.
It is accordingly dismissed” the Supreme Court stated in its judgment on April 15, 2004.
Specialists know that it is impossible to get conclusive evidence from studies with a weak data base. However, such studies will continue often as public relations exercises! No one wants to call a spade a spade!
K.S.PARTHASARATHY
ksparth@gmail.com
[K.S.Parthasarathy is former Secretary Atomic Energy Regulatory Board]
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