Study: Most ocean fish still tainted by toxic chemicals, but levels are gradually decreasing

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Levels of pollutants in seafood vary widely in different regions. @bberwyn photo.

More research needed to determine risk to consumers

Staff Report

Fish in all the world’s oceans are still tainted by a stew of potentially toxic chemicals, but concentrations of the pollutants have decreased in the past 30 years, according to a new study by researchers with the Scripps Institution of Oceanography at UC San Diego.

The scientists said their findings included both good and bad news. On the up side, the findings suggest that the global community responded to the calls-to-action, such as in the Stockholm Convention, to limit the release of potentially harmful chemicals into the environment.

But they also cautioned that, although pollutant concentrations in marine fish are steadily declining, they still remain quite high, and that understanding the cumulative effects of numerous exposures to pollutants in seafood is necessary to determine the specific risk to consumers.

The research was published in the journal PeerJ.  It was based on an analysis of hundreds of peer-reviewed articles from 1969-2012. The pollutants studied included older ‘legacy’ chemicals, such as DDT and mercury, as well as newer industrial chemicals, such as flame retardants and coolants.

“Based on the best data collected from across the globe, we can say that POPs can be anywhere and in any species of marine fish,” said Scripps biologist Stuart Sandin, a co-author of the study.

Persistent organic pollutants were found in fish in all of the world’s oceans, with highly variable concentrations in the consumable meat of marine fish. The analysis revealed that average concentrations of each class of POP were significantly higher in the 1980s than is found today, with a drop in concentration of 15-30 percent per decade.

“This means that the typical fish that you consume today can have approximately 50 percent of the concentration of most POPs when compared to the same fish eaten by your parents at your age,” said Bonito, the lead author of the study. “But there still remains a chance of getting a fillet as contaminated as what your parents ate.”

The researchers also compared the results to federal safety guidelines for seafood consumption and found that the average levels of contaminants were at or below the health standards set by the U.S. Environmental Protection Agency (EPA). Mercury and PCBs (polychlorinated biphenyl) concentrations were at the EPA threshold for occasional human consumption, while concentrations of DDT were consistently much lower than the established threshold.

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