Are Bay Harbor Seals Facing a New Chemical Health Threat?
Between globs of oil, six-pack rings, used condoms, and discarded sippy cups, harbor seals have plenty of hazards to dodge in San Francisco Bay. But some potential threats to their health may be more insidious. An “emerging contaminant” found circulating in blood samples from harbor seals is perfluorooctane sulfanate (PFOS), a persistent compound used in Scotchgard, fire extinguisher foam, and other stain-resistant and water-repellent coatings. (In 2002, Scotchgard’s manufacturer 3M voluntarily withdrew its PFOS products, at the same time saying there was no health risk.) PFOS has been detected in the marine environment worldwide, but preliminary work done by the Marine Mammal Center’s marine biologist Denise Greig, in collaboration with the San Francisco Estuary Institute, suggests that the chemical’s levels in seals from the San Francisco Bay may be two to three times higher than levels reported in seals from the Baltic Sea or Norwegian Arctic. Greig plans to follow up on these resul
