- In a study issued in 2000, B.C. Fisheries identified areas of the
B.C. Coast which included some shellfish farms that have "problematic
residues of Cd [cadmium] in farmed Pacific oysters"1,2.
No routine testing is done of cadmium levels in the B.C. shellfish sold
to consumers whereas a number of sites that have been tested exceed
internationally recommended concentrations by several times. Nor has
any effort been made to site shellfish farms away from locations with
high cadmium levels.
According to Health Canada, cadmium is a toxic metal associated with significant
health risks . When consumed, it is deposited in the soft tissue of the
body with 50 -70 % accumulating in the liver and kidney. Accumulation
of low levels are tolerated by the body, however, higher levels of chronic
exposure can lead to kidney dysfunction and possibly breast cancer3.
The World Health Organization/FAO Joint Expert Committee on Food Additives
and Contaminants considers cadmium a carcinogen.
In February, 2002 Health Canada released consumption guidelines for regular
consumers of BC grown oysters4.
- “The maximum monthly intake guidelines for regular consumers
of BC grown oysters are as follows:
Children - about 1 1/2 oysters per month;
Adults - about 12 oysters per month
On July 7th, 2006, the Codex Alimentation Commission set new international
standards on maximum allowed levels of contaminants including lead and
cadmium5. The Codex is a joint food standards body run by two United
Nations [the World Health Organization (WHO) and the Food and Agriculture
Organization (FAO). The standards apply to food consignments that move
in international trade. Maximum limits of cadmium in marine bivalve molluscs
and cephalopods set by Codex Standards are:
- “Cadmium should not exceed two milligrams per kilo of marine
bivalve molluscs, excluding oysters and scallops, and the same amount
in cephalopods such as squids and octopus.”
- It is noted that European Union and Asian markets still have a 1
and 2 mg/kg limit respectively of cadmium for oysters.
Some B.C. oysters contain cadmium levels up to 4 milligrams per kilo1,
several times the maximum amount allowed by Codex specifications, the
European Union, and several Asian countries. BC mussels and scallops are
also known to have elevated levels of cadmium, although the precise levels
for many localities are still being determined.
The Association for Responsible Shellfish Farming advocates systematic
independent scientific sampling and testing of all B.C. oysters
for cadmium and other toxins and the banning of sales of shellfish containing
cadmium levels above the international standards considered to expose
the public to health risks.
- Kruzynski, George. 2000. "Cadmium in BC farmed oysters: A review
of available data, potential sources, research needs and possible mitigation
strategies." Canadian Stock Assessment Secretariat Research Document
2000/104. Canadian Fisheries and Oceans Science: Ottawa. ISSN 1480-4883.
- Kruzynski, G.M. 2004. "Cadmium in oysters and scallops: The
B.C. experience." Toxicology Letters 148(3):159-169.
- "Cadmium Exposure and Breast Cancer Risk” is a paper in
the Journal of the National Cancer Institute, Vol. 98, No. 12, June
21, 2006 indicating that there is evidence that further study is needed
to investigate the probable relationship between cadmium and breast
- "Food Safety Facts on Bivalve Shellfish in British Columbia."
Canadian Food Inspection Agency Fact Sheet: http://www.inspection.gc.ca/english/fssa/concern/specif/bivalvee.shtml
- Frances Williams. 2006. Financial Times, 7 July. Also see: www.codexalimenetarius.net