Marine animals are exposed to a hazardous cocktail of pesticides such as DDTs and PCBs and more lethal ones like brominated flame retardants, an extensive review has revealed.
The research was done by Eric Montie, who conducted it as a student in the Woods Hole Oceanographic Institution-MIT Joint Graduate Program in Oceanography and Ocean Engineering and as a postdoctoral fellow at the Woods Hole Oceanographic Institution (WHOI).
Co-author Chris Reddy, an associate scientist in the WHOI Marine Chemistry and Geochemistry Department describes the work as "groundbreaking because Eric measures a variety of different chemicals in animal tissues that had not been previously explored. It gives us greater insight into how these chemicals may behave in marine mammals."
Montie analyzed both the cerebrospinal fluid and the gray matter of the cerebellum in eleven cetaceans and one gray seal stranded near Cape Cod, Massachusetts.
His analyses include many of the chemicals that environmental watchdog groups call the dirty dozen, a collection of particularly ubiquitous pesticides that were banned in the 1970s because of their hazards to human health.
But, the Montie study goes much further in the scope of contaminants analyzed, and many of the contaminants are anything but benign.
The chemicals studied include pesticides like DDT, which has been shown to cause cancer and reproductive toxicity, and PCBs, which are neurotoxicants known to disrupt the thyroid hormone system.
The study also quantifies concentrations of polybrominated diphenyl ethers or PBDEs (a particular class of flame retardants), which are neurotoxicants that impair the development of motor activity and cognition.
This work is the first to quantify concentrations of PBDEs in the brains of marine mammals.
The results revealed that concentration of one contaminant was surprisingly high.
According to Montie, "The biggest wakeup was that we found parts per million concentrations of hydroxylated PCBs in the cerebrospinal fluid of a gray seal. That is so worrisome for me. You rarely find parts per million levels of anything in the brain."
The work of Montie and his colleagues lays the groundwork for understanding how environmental contaminants influence the central nervous system of marine mammals.
The research provides tools to ask deeper questions about how the ever-growing list of contaminants in the ocean affect the neurological development of marine mammals.