EPA reports finding trace levels of iodine-131 in drinking water in Boise, ID and Richland, WA. These results are worrying for a number of reasons, not the least of which is the way EPA tries to put these them in context in the report:

Even an infant would have to drink almost 7,000 liters of this water to receive a radiation dose equivalent to a day’s worth of the natural background radiation exposure we experience continuously from natural sources of radioactivity in our environment.

This wording is problematic, and represents an opinion. In my view, EPA should either be simply reporting the numbers so that readers and the news media can solicit expert opinions on them, or attaching some people’s names (and biographical information) to such statements if they do feel a need to provide interpretation.

Why is this wording problematic? One reason is it makes an inappropriate comparison between ingested radioisotopes, which can be readily incorporated into body tissue; and background radiation, which includes radiation emitted from non-ingested sources such as building materials and cosmic rays.

In addition, these results represent a point in time, and say nothing about variations over time. Wind, rain and other factors will affect what ends up in drinking water at different places at different times. Some caveats are in order when making such statements.