The level of mercury has dropped 50 percent in ocean fish and the level of polychlorinated biphenyls (PCBs) has fallen more than 90 percent in the last 40 years, according to a new review by researchers at the Scripps Institution of Oceanography in La Jolla, California. Other toxins, including DDT, also are showing up far less in fish samples, reports the LA Times.
The scientists looked at roughly 2,700 studies of pollutants taken from fish samples around the world between 1969 and 2012. Decades of public pressure and increased regulation have had a dramatic impact on ocean contamination. That said, many wild fish still showed toxicity levels beyond what is considered safe to eat regularly. Perhaps most surprising, the study found that smaller fish like mackerel and sardines, which were thought to be safer to eat since they fall further down the food chain, were sometimes more contaminated than large species like shark and swordfish.
“There’s just a lot more complexity out there,” Stuart Sandin, a marine biologist at Scripps and senior author of the study, published last month in the journal PeerJ, told the Times. The study didn’t specifically address dietary recommendations, but in general found that most fish met U.S. safety guidelines.