Many consumers are wondering which fish are safe to include on their shopping lists after U.S. officials discovered last week that melamine-tainted fish feed was delivered to dozens of fish farms in Canada and the United States.
Officials in both countries say that fish raised on the tainted feed are still safe for people to eat. The same contaminant in gluten sickened pets and led to massive pet-food recalls this year. But melamine is not known to accumulate in fish tissue, officials say.
The melamine scare raises questions about contaminants in wild and farmed fish - and about oversight by Canadian health authorities.
U.S. authorities, not Canadian officials, discovered the melamine-laced gluten from China in fish feed, says Jay Ritchlin, marine conservation specialist with the David Suzuki Foundation. "That says something right there," he says.
Melamine is added to gluten by producers in countries such as China to make it appear to have a higher protein content. "It's a trick," Mr. Ritchlin says.
In spite of the melamine concerns, Linda Sams, a marine biologist, says Canadians can safely eat farmed and wild fish. "In Canada, we do a pretty good job of regulating our food sources," says Ms. Sams, CEO of the B.C. Centre for Aquatic Health Sciences.She says Canadians should in fact be getting more fish in their diets. But health experts are concerned about high levels of mercury in certain wild fish, and about concentrations of pesticides and industrial pollutants such as PCBs (polychlorinated biphenyls) and dioxins in farmed fish.
"Farmed fish has about 10 times the concentration of PCBs, dioxins and pesticides that wild salmon has," says David Carpenter, director of the Institute for Health and the Environment at the University at Albany.
Farmed fish can be contaminated by pollutants in the water, pesticides in vegetable oil used in feeds, or other chemicals, Dr. Carpenter says.
He co-authored a 2006 study that analyzed salmon taken from 24 fish farms in Atlantic Canada and 18 in British Columbia. Using a formula from the U.S. Environmental Protection Agency, Dr. Carpenter and five other U.S. scientists concluded that a consumer could eat no more than one meal of the farmed fish every two months to avoid an increased cancer risk.
In Canada, after analyzing a large sample of wild and farmed fish for PCBs, Health Canada reported in 2004 that farmed salmon posed no health risk to consumers.
Even though farmed salmon has a greater concentration of PCBs and dioxins, the cardiovascular health benefits of eating fish far outweigh the risks, according to a 2006 report from the Harvard School of Public Health and Harvard Medical School.
Canada's updated Food Guide, released in February, encourages people to eat more fish - two 75-gram servings weekly of low-mercury fish - because of its high-quality protein and heart-smart omega-3 fatty acids.
In March, Health Canada issued new recommendations for consumption of fish high in mercury, such as swordfish, king mackerel and canned albacore tuna. The new standards for mercury are among the most stringent internationally, Health Canada says.
The controversies over the toxins in various fish can be daunting for consumers. Some shoppers try to reduce their risk of exposure by eliminating certain kinds of fish.
"I try not to eat farmed fish at all," says Geoff Horne, while shopping at Granville Island Public Market in Vancouver. "I'd much rather eat salmon that I catch myself."
Kosta Zogaris, owner of the Salmon Shop in North Vancouver, says he began to sell only wild salmon seven years ago.
"Customers are adamant that they never see farmed salmon on our shelves." he says. Despite the lower price of farmed salmon, Mr. Zogaris says he's had just one request for the farmed variety in two years.
Customers increasingly want to know where their fish comes from, says Vince Morrison, general manager of the Fisherman's Brother fish market in Thornhill, Ont.
"They think, 'Oh, that's a nice place for a fish to come from, that sounds like a safe place,' " he says. "It's a perception thing."
Shoppers don't usually ask about potential contaminants in the fish they're buying, he says.
Ratings on fish safety published by health-advocacy and environmental groups often disagree, which doesn't make the choice at the fish counter any easier, Dr. Carpenter says. The reason, he says, is that scientists have not studied the accumulations of mercury, carcinogens and other contaminants combined in all species and habitats.
He says he tries to eat fish that are not known to have high levels of contaminants, such as perch and flounder.
"I don't advise people to stop eating fish, because it's a healthy food," he says. "But we are really failing in providing accurate information that allows consumers to make informed decisions."
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Troubled waters
Confused at the fish counter? You're not alone. In March, Health Canada put out stricter guidelines for eating fish high in mercury, just one of the contaminants to worry about. At the same time, the Canada Food Guide encourages us to eat more fish for its healthy fats and high quality protein. Here are recommendations to keep in mind.
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MERCURY
Risk: damage to brain development in infants and children.
CANADA
(Health Canada)
General population
Canada's Food Guide recommends that Canadians eat at least two servings (75 grams each) of fish per week but limit consumption of fish considered high in mercury (fresh or frozen tuna, shark, swordfish, marlin, orange roughy and escolar) to no more than 150 grams per week.
Pregnant women, women who might become pregnant, nursing mothers
Eat no more than 150 grams per month of fish high in mercury, and no more than 300 grams a week of canned albacore (white) tuna, higher in mercury than canned light tuna.
Children 5-11 years old
Eat no more than 125 grams per month of fish high in mercury, and no more than 150 grams a week of canned albacore (white) tuna.
Children 1-4 years old
Eat no more than 75 grams per month of fish high in mercury, and no more than 75 grams a week of canned albacore (white) tuna.
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U.S.
(U.S. Food and Drug Administration)
General population
The federal agency recommends that Americans include fish as part of a balanced diet. According to the agency, the mercury risk from eating fish and shellfish is not a health concern for most people.
Pregnant women, women who might become pregnant, nursing mothers
Do not eat shark, swordfish, king mackerel and tilefish (high in mercury). Eat up to 340 grams a week of fish that are lower in mercury. Eat no more than 170 grams a week of albacore (white) tuna.
Children 5-11 years old
Do not eat shark, swordfish, king mackerel and tilefish (high in mercury). Eat up to 340 grams a week of fish that are lower in mercury. Eat no more than 170 grams a week of albacore (white) tuna.
Children 1-4 years old
Do not eat shark, swordfish, king mackerel and tilefish (high in mercury). Eat up to 340 grams a week of fish that are lower in mercury. Eat no more than 170 grams a week of albacore (white) tuna.
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CARCINOGENS
(DDT, pesticides, PCBs, dioxins) Risk: cumulative levels linked to cancer.
SCIENTIFIC STUDIES*
Eat no more than one meal of farmed salmon from Atlantic Canada or British Columbia every two months.
Eat no more than one meal of farmed salmon from Europe every five months.
Vegetarian fish are better than predatory fish; small fish (lower on the food chain) are better than big fish.
*SOURCE: Dr. David Carpenter, co-author of "Consumption advisories for salmon based on risk of cancer and noncancer health effects," published in the journal Environmental Research (Vol. 101, No. 2, June 2006(
COMPILED BY ADRIANA BARTON