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High levels of cadmium found in area oysters

Expert calls for stricter control
Kyle Wells

A recent report from a Simon Fraser University professor criticizes the oyster farming industry for ignoring dangers associated with the presence of cadmium in its product and points to Desolation Sound as a particular “hot spot” for the potentially harmful substance.

Leah Bendell, who specializes in ecotoxicology and biological sciences, published an article in a recent Toxicology Letters journal issue entitled “Cadmium in shellfish: The British Columbia, Canada experience.” In the article Bendell writes about high levels of cadmium in BC oysters and about the industry’s reluctance to tackle the issue directly.

Bendell’s research took place over a three-year period and in relation to 25 specific areas. She and her researchers examined more than 2,000 oysters over the course of her study and found an average level of 2.23 micrograms of cadmium per gram of oyster. The Canadian Food Inspection Agency in its own study found an average of 2.6 micrograms per gram, the level on which that Health Canada bases its own consumption rates.

Bendell’s research revealed Desolation Sound to have higher levels of cadmium in oysters compared to other regions. It’s hard to say why this is but Bendell said research suggests Desolation Sound oysters are getting their cadmium from a terrestrial source rather than a marine source. Within the sound, Bendell points to Redonda Bay, Thors Cove and other areas as particularly worrisome.

A study released this month by the University of Northern British Columbia for Health Canada on First Nations Food, Nutrition and Environment examined toxicity levels in the traditional foods of the Tla’Amin (Sliammon) First Nation. Oysters from Sliammon households, the report reveals, on average contain 3.56 micrograms of cadmium per gram of oyster. Bendell said these numbers are very high but correspond to her own data.

“Our environment is under siege in a lot of ways, especially given our location in the Georgia [Strait] and Salish Sea,” said Hugh Prichard, executive director of Tla’amin Community Health Services Society. “From a traditional food perspective, it’s a huge concern.”

High cadmium levels in humans have been linked to a number of health issues. Data Bendell reviews in her article indicate that cadmium ingested through food accumulates in the kidneys, eyes and other tissues and organs of exposed individuals. Adverse affects of cadmium on the kidney and bones have been observed in populations more frequently exposed to the metal.

Current Health Canada consumption rates sit at 460 grams of oysters per month for adults, which amounts to about 12 oysters. Considering the cadmium levels her research reveals, Bendell said consuming an average of four oysters a month is a safer bet and children shouldn’t eat them at all. If oysters were known to be coming from an area with low levels of cadmium consumers generally wouldn’t have to worry about intake levels, said Bendell.

“They also are a very good source of protein and have lots of benefits so you’re not saying don’t eat them at all,” said Bendell. “You’re saying be aware of the amount of cadmium and adjust your intake accordingly.”

People need to know the facts on oysters, according to Bendell, so that they can make informed decisions. In her paper she accuses the industry of focusing on a defensive response rather than putting effort into determining sources of cadmium and ways to mitigate contamination. Bendell would like to see cadmium levels taken into account when deciding on areas to establish oyster farms and would like to see support and compensation offered to farmers so that they can move their operations to safer waters.

BC Shellfish Growers Association was unavailable for comment.