The WSJ's Numbers Guy on Chernobyl deaths (Measuring Chernobyl's Fallout):
How many people died because of the Chernobyl nuclear-reactor explosion, which spewed radiation across northern Europe? Twenty years after the accident, the death toll remains in dispute.
This month, the World Health Organization estimated "up to" 9,000 people died or will die of cancer because of the incident, which unfolded in the early morning hours of April 26, 1986. The number was 6,700 to 38,000 in a recent report published in a peer-reviewed journal, from the Lyon, France-based International Agency for Research on Cancer, an agency governed by the WHO and 16 member nations. Greenpeace International, which opposes nuclear power, published its own report, based partly on papers from former Soviet nations. Greenpeace estimates the death toll is between 93,000 and 200,000, including cancer deaths and other illnesses like immunity disorders.
As is his wont (Webster's Dictionary says this means "habitual way of doing"), the Numbers Guy dissects these differences.
Um, not surprisingly, Greenpeace's estimate is the most bogus:
Greenpeace, sparked by the September announcement, brought together more than 50 scientists -- mostly from Belarus, Ukraine and Russia, the most-affected nations -- to write a report compiling papers published in regional medical journals. Ivan Blokov, leader of Greenpeace's Chernobyl project and an editor of the report, told me that the report is "scientifically based," with no political statements.
However, the report relied heavily on some questionable methods. It assumed that Chernobyl was responsible for an overall increase in cancer rates, but Chernobyl's effect on those rates is difficult to isolate from other factors, such as changes in smoking rates and improvements in the diagnosis of cancer. Also, researchers wanted to estimate how many people exposed to Chernobyl radiation developed cancer other than thyroid cancer, which usually isn't fatal. To do so, they studied how cancer rates rose in post-war Hiroshima and Nagasaki, and looked at the ratio of thyroid cancers to other cancers in those cases. They applied a similar ratio for Chernobyl. But Japan's overall cancer rates differ from Europe's -- Japan has a higher rate of stomach cancer but a lower rate of lung cancer, for instance -- so it's not clear the same ratios would hold true.
