When I was a child, my family would visit friends on Vancouver Island for a big summer celebration. I have great memories of my Dad teaching us kids how to gather, shuck and cook oysters to add a taste of the ocean to our dinner.
In BC, we are lucky to be able to enjoy fresh seafood like oysters and scallops. However, BC oysters and whole scallops contain cadmium, a mineral. Cadmium in large amounts can damage kidneys and may be linked to other health issues like high blood pressure and diabetes.
Cadmium is found naturally in oceans and soil. Mining and agriculture add to these levels. The Pacific ocean has more natural cadmium than the Atlantic ocean and our unique BC ocean currents and tides have just the right movement to bring cadmium toward our coast. Because oysters and scallops filter the ocean to feed, they naturally gather cadmium.
It’s Ok to eat the muscle (the pale fleshy part) of the scallop, which is the part you get when you buy scallops from the store. The muscle is low in cadmium. When you eat the whole scallop, however, you also eat the kidney and other organs which are higher in cadmium.
Health Canada currently recommends people limit BC oysters and whole scallops to reduce cadmium. They state that healthy adults eat a maximum of 12 BC oysters per month. Because children may absorb more cadmium from foods, they should eat a maximum of one BC oyster per month.
Cadmium levels are at their lowest during spring and summer in BC oysters. Enjoy them in moderation according to the Health Canada guidelines above. Oyster lovers may freely eat Maritime east coast varieties as they have lower levels of cadmium.
Certain groups of people are at higher risk for health issues from too much cadmium and should further limit the amount of oysters and whole scallops they eat:
- People who smoke. They already have higher amounts of cadmium in their bodies from cigarettes.
- People with diabetes or kidney disease. Too much cadmium can make current kidney problems worse.
- People who have low iron levels, especially women. People who are low in iron may absorb more cadmium from food.
- People who harvest or farm oysters and scallops. They may eat oysters and whole scallops from the shell more often and therefore get more cadmium from foods.
- People who hunt or eat game meat including organ meat. Organ meats are also higher in cadmium, and adding extra cadmium from BC oysters can increase potential risks from too much cadmium.
The bottom line: eating a variety of seafood can be part of healthy eating. Enjoy fish such as salmon, cod and halibut often, and include other BC seafood such as prawns, crab, clams, or mussels. Eat oysters and whole scallops in moderation and check for contamination updates from Fisheries and Oceans before harvesting shellfish like oysters and scallops.
Add a taste of the sea to your meals. Try BC seafood baked, steamed or cooked on the barbeque! What’s your favourite way to cook seafood? What seafood recipes does your family enjoy?
British Columbia Centre for Disease Control: Cadmium in BC Shellfish
Government of Canada: Shellfish Food Safety
Food Safety: Mercury in Fish
Fisheries and Oceans Canada: Shellfish Contamination in the Pacific Region
Shellfish Safety Notes: Shellfish Advice for Consumers