PCB Levels in Dolphins Raise Red Flags for Seafood Eaters
Dave Thier Contributor
(Feb. 19) — Researchers have found dangerously high levels of PCBs in dolphins off the coast of Georgia, raising concerns for humans dining on the same fish from the seafood-rich waters, the Charleston Post and Courier reported.
The discovery is especially alarming considering that the Environmental Protection Agency banned PCBs, or polychlorinated biphenyls, for most uses in 1979. In 2009, however, the researchers found that these dolphins had the highest levels of PCBs in the fat of a marine mammal ever. Dolphins eat far more fish than humans, and the massive amount of PCBs that they’ve been ingesting is wreaking havoc on their health.
“Some of these (dolphins) are living on the edge,” Lori Schwacke, principal scientist at the National Oceanic and Atmospheric Administration’s Oceans and Human Health Center of Excellence at Fort Johnson, told the Post and Courier. “Their immune systems have been suppressed to the point where the outbreak of a single virus could result in mass kills. … While we don’t understand the risk to people yet, it’s enough of a red flag to make us want to do further experimentation.”
As a coolant, PCBs were valued for chemical stability, and they tend to have very long half-lives. The fact that the researchers are finding such high levels of a compound banned 30 years ago suggests that these substances posses a troubling longevity.
The researchers originally tested animals near Brunswick, Ga., a heavily polluted area home to four federal Superfund sites. But the real surprise came when they tested animals in an estuarine research reserve 30 miles away and discovered that those dolphins had similar PCB levels as the Brunswick dolphins. As animals, dolphins are homebodies, meaning that it’s likely the fish are doing the traveling.
Schwacke worried that this suggests the PCBs, rather than remaining stationary in the sediment, are moving out into the coastal ecosystem.
Georgia fisheries recently have been hit hard by regulations limiting grouper and red snapper fishing, but these findings may not yet add to those woes. The implication of PCBs in dolphins doesn’t necessarily outweigh the health benefits of eating seafood, but still warrants further research into just how entrenched these dangerous chemicals are in the coastal ecosystem and diet.