The NY Times reported a couple of days ago about an EPA publication, out in September 2009,  entitled The National Study of Chemical Residues in Lake Fish Tissue (available here).

It’s interesting that the EPA website on the study has an in initial Q&A, the first one being

Why is this study important?

The National Lake Fish Tissue Study is important because it:

Generated data to develop the first statistically-based national estimates of the median concentrations of persistent, bioaccumulative and toxic chemicals in lake fish.

Provided a national baseline for tracking reductions of persistent, bioaccumulative, and toxic chemicals in freshwater fish as a result of pollution control activities.

There’s no mention of health implications.  For these important implications of the results, one has to skip over this Q&A,  skip the Executive Summary (here), and go to the conclusions section of the full report (here), which says

Elevated mercury concentrations in fish are the leading cause of fish advisories. In 2008,
43% of the total lake acres in the United States were under advisory for mercury. Results
from the National Lake Fish Tissue Study confirm that mercury is widely distributed in lakes
and reservoirs across the country.Study data show that mercury was detected at quantifiable
levels (i.e., concentrations at or above the quantitation limit) in every fish sample collected
from all 500 locations sampled for the study.

mercury concentrations in the predator samples occurred above the 300 ppb
human health screening value for mercury at nearly half of the lakes in the sampled population.
These elevated mercury concentrations in predators apply to more than 36,000 lakes
in the lower 48 states. Overall, the results from this statistically-based study underscore the
pervasive nature of mercury deposition on lakes and their surrounding watersheds in the
conterminous United States.

Total concentrations of DDT and chlordane rarely exceeded their respective human health
screening values of 69 ppb and 67 ppb.

The predator species include bass and trout, and bottom dwellers include carp and catfish.

This study cries out for further discussion of its implications.  The report gets into many important issues regarding how to conduct such a study (with great care and effort), but I’d think they would want to carry things further.  How do the numbers affect fish farming, for example?  How do these data compare to seafood concentrations?  How are fish advisories faring as a method of reducing consumption of tainted fish?