Chemicals pose growing risk to sea life

Louise Dickson
Times Colonist
Friday, May 13, 2005

A regional study of harbour seals' usual food has found flame-retardant chemicals in higher concentrations in Puget Sound than the persistent pesticide DDT.

"That's pretty staggering," said marine mammal toxicologist Peter Ross. "For the first time, a new chemical has emerged to challenge the dominance of PCBs and DDT."

The study by Ross, UVic PhD student Donna Cullon and Washington state scientist Steven Jeffries compared the level of contaminants in the harbour seal food baskets -- a sample of their normal food -- in the Strait of Georgia and Puget Sound. It found PCB levels are seven times higher in Puget Sound than the Strait of Georgia. Their findings confirm a recent study that found harbour seals in Puget Sound are seven times more contaminated than B.C. seals.

It's not just bad news for harbour seals living in Puget Sound. It's bad news for endangered southern resident killer whales, found in the protected inshore waters of the Strait of Georgia, Puget Sound, Haro Strait and southern Vancouver Island.

"Puget Sound is a toxic soup, a PCB hotspot," said Ross, who works for Fisheries and Oceans at the Institute of Ocean Sciences in North Saanich. "That's a concern for the state of Washington, it's a concern for Canada and it's a concern for killer whales."

Ross is also concerned that the flame-retardant chemicals -- polybrominated diphenyl ethers, or PBDEs -- may increase the threat to the immune systems, reproductive health and normal growth and development of killer whales.

"In the absence of regulations, the concentration of flame-retardant chemicals may even surpass PCBs in the environment," said Ross. "There's a history of contamination in both jurisdictions. We have to take steps to prevent these chemicals from getting into killer whale habitat and the food web."

Canada is moving to partially regulate two of three PBDE products, he said.

The researchers took 200 samples from Puget Sound and the Strait of Georgia, capturing 10 to 12 prey-sized fish of each species. B.C. harbour seals eat a diet which is 35 per cent herring, 30 per cent hake and a mix of rockfish, tomcod and salmon. Harbour seals in Puget Sound eat a wider variety of fish.

The survey provides a realistic idea of what chemicals, and in what concentrations, the seals are exposed to, said Ross. Samples taken from Vancouver, Victoria, Crofton and Hornby Island in the Strait of Georgia show PCBs remain the No. 1 concern for the seals. PCBs and DDT were found in relatively high concentrations. Flame-retardant chemicals were the third-highest toxic concentration.

In Puget Sound, PCBs topped the list of toxic chemicals. Flame-retardant chemicals were found in higher concentrations than DDT.

Other studies are underway to find out how these toxic chemicals accumulate in seals and to study the effect of these chemicals on the health of harbour seals. The marine mammals are good environment sentinels because they don't migrate and they eat fish, said Ross.

Oceanography may explain some of the higher level of contamination in Puget Sound. The sound is shallower and smaller than the Strait of Georgia, and fewer fresh water streams flowing into it. It has a shallow entrance, so there is less tidal flushing. The Strait of Georgia has more sedimentation and more tidal flushing.

FACTS ON PBDE

- PCBs, which were used in electric transformers and as industrial lubricants, have been banned since 1977.

- PBDEs, found in furniture, plastics, automobiles, computers, electronics and insulating material, are still in production around the world. They are not thought to be as toxic as PCBs, but they are structurally similar.

- PBDEs leach into the environment at dumps and manufacturing facilities. They accumulate in the fatty tissues of humans and animals. They're found in household dust, and a recent Northwest Environment Watch study testing the breast milk of 40 nursing mothers found the chemical in all 40 samples.

- The European Union and California have banned their use. Washington state is considered a ban.

- Canada is assessing the environmental and health effects of the chemicals. Last year, an Environment Canada draft report found an increase of PBDEs since the early 1990s. It also found levels in some areas "may pose a risk to the development of some wildlife and invertebrates."

CREDIT: Debra Brash, Times Colonist
Marine mammal toxicologist Peter Ross, with a harbour seal off Esquimalt, found in a recent study that dangerous flame retardants are reaching PCB levels in the waters of Puget Sound.