Reacción a "Counties in the United States near operating nuclear power plants have higher cancer mortality rates"

This is a surprising paper. It is based on numbers of deaths from all types of cancer among the middle-aged and elderly in US counties, which are large areas to use in a study of the putative effects of “proximity to nuclear power plants”. It is an “ecological” study dealing with “exposures” that are county averages rather than those of individuals, and the problems of (mis)interpreting the results of such studies are well-known. This study illustrates these problems.

“Proximity” means the distance of the “centre” of a US county from a nuclear power plant, where counties are those within 200 km of a nuclear power plant. The data for any communities that might be reasonably considered as “close” to a nuclear power plant (e.g., within, say, 10 km), and therefore reasonably considered as affected most by discharges, will be swamped by the data for rest of the county in which the communities lie.

“The authors make no attempt to relate their findings to the radiation doses actually received from radioactive discharges at the level of US counties, or how these doses compare with those received by everyone from natural background radiation. This is a major omission in their interpretation of results.

“The authors acknowledge that cancer types vary in their sensitivity to radiation, but they offer no indication of whether their results show any consistency by type of cancer, e.g., lung cancer, or whether this is a “broad brush effect” covering a wide variety of cancer types. This is disappointing.

“The central question must be, does an ecological study like this one, dealing with average cancer mortality rates at the US county level, have any real chance of adequately accounting for those major background individual risk factors – those factors (e.g., smoking) that cause the great majority of the cancers that currently are responsible for about a fifth of deaths in the USA – to reliably find a signal of the very small additional cancer risk from radioactive discharges from nuclear power stations?  I very much doubt it.

“This study reminds me of another ecological study based on US counties that appeared to show that inhaling the naturally occurring radioactive gas radon reduced the risk of dying from lung cancer. In fact, this result was due to a failure to properly account for smoking at the individual level.

“Yes, this is a (very) surprising paper.