Pollutant Levels in Store-bought Freshwater Fish Surprise Researchers
White bass that was caught in the wild and sold commercially
contained significantly higher levels of mercury, arsenic and selenium
than fish caught near former industrial areas, according to a
University of Pittsburgh study.
According to study results, mercury levels were 2.2 to 4.8 times
higher in fish caught in the Canadian Lake Erie and available
commercially than in fish caught near former iron and steel mills on
the Allegheny and Monongahela rivers in Pittsburgh. While several of
these mills have been closed for many years, the nearby rivers continue
to contain high levels of pollution from sewer overflows and active
For the study, researchers used local anglers to catch 45 white bass
at two locations in Pittsburgh and bought 10 white bass locally that
were caught in the Canadian Lake Erie. They analyzed the fish for
levels of mercury, arsenic and selenium. In addition to higher levels
of mercury, the store-bought fish had levels that were 1.7 times higher
for arsenic and 1.9 times higher for selenium.
"We were surprised by our results since we had hypothesized that
levels of contaminants in fish would be higher in specimens caught near
once heavily polluted sites," said Dr. Conrad D. Volz, principal
investigator, department of environmental and occupational health,
University of Pittsburgh Graduate School of Public Health. 'These
results indicate to us that purchasing fish from a local market cannot
guarantee food safety. We recommend a more rigorous testing program for
commercial freshwater fish with particular attention to fish entering
the United States from other countries."
According to Volz, the results also may indicate that sediments in
Lake Erie remain contaminated because of only relatively recent
reductions in industrial pollution and active coal-fired power plant
air emissions from facilities located around and to the southwest of
Lake Erie, as well as wastewater from plants located on the lake.
Mercury, arsenic and selenium are markers for coal-burning pollution
through air emissions and water pollution and from fly ash piles that
are absorbed into surrounding soil. Fly ash is the residue left after
coal burning that is often stored at the plant site.