Purdue News
Purdue News
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January 31, 2001 Three-year study shows farm-raised fish safeWEST LAFAYETTE, Ind. – While concerns continue about high levels of metals such as mercury found in some fish, a study recently completed at Purdue University shows that fish bought in grocery stores or restaurants are generally safe to eat. The study examined heavy metals in catfish, trout and crawfish grown in aquaculture facilities across the southern United States. Researchers tested for nine metals including mercury, lead, cadmium, chromium and arsenic over a three-year period. Levels of mercury, the only metal to have an action limit set by the Food and Drug Administration, were on average 40 to 100 times lower than the one-part-per-million limit. "These findings are supportive of aquaculture products given the current debate over the safe levels of mercury in offshore fish like swordfish, shark, mackerel and large tuna," says Charles Santerre, associate professor in Purdue's Department of Foods and Nutrition. Santerre directed a team of researchers from nine universities to complete the study. "Since virtually all catfish and trout purchased from grocery stores and at restaurants are farm-raised, consumers should continue to enjoy these products and benefit from their nutritional value," he says. "Fish is about 10 percent protein and can be high in omega-3 fatty acids." The 2000 Annual Report of the U.S. Seafood Industry, published by H.M. Johnson and Associates, indicates that catfish is the fifth most popular seafood in the United States. When compared to captured fish, catfish ranks third in total production, trailing Alaskan pollock and Pacific salmon, but leading Pacific cod. Domestically, catfish is the leading fish grown commercially, particularly in warmer southern states like Mississippi, Louisiana, Texas and Alabama. Catfish represented 70 percent of total fish production in 1998-99, and trout represented 10 percent of U.S. aquaculture output. Santerre's study, to be printed in the February issue of the Journal of Food Science, follows another report published last March in the same journal by the same group of investigators. In that study they reported very low levels of 34 pesticides in the same fish species. Santerre warns, however, that while data supports the safety and benefits of aquaculture products, consumers should still use caution when eating fish they catch. "At least 34 states have issued consumption advisory alerts to protect anglers and their families from harmful contaminants," he says. "In Indiana, as for many other states for instance, state agencies have found high levels of mercury and PCB in fish caught from local rivers, streams and lakes." Two Purdue surveys, conducted in Indiana and reported in 1999, found that while 19 percent of residents have fishing licenses, as many as 38 percent of these licensed anglers do not follow the advisories. Santerre indicated that this may translate to as many as 600,000 residents, or 10 percent of Indiana's population, that may be exposed to harmful levels of pollutants. "I am not aware of any data that suggest that Indiana is any different from other states," Santerre says. "On the one hand, we want anglers to enjoy fishing. However, we also want them to eat fish that is safe. If they are not sure about the safety of the fish that they catch, then it is advisable to catch-and-release and purchase a farm-raised product at the market or in a restaurant." Santerre notes that infants and children younger than 18 are likely to be more sensitive to environmental pollutants such as mercury in fish. "It is also important that we protect the unborn child," he says. "This is a stage of life where contaminants may have the greatest impact on the health and development of the child. Residues of some pollutants, like PCB, may be stored in a woman's body for longer than six years and then get passed to her children through the placenta or breast milk. I worry that anglers with good intentions may bring contaminated fish home to feed to their family." Santerre has developed a Web site that contains information for Indiana anglers relating to the toxic effects of certain pollutants. "Our site may be a good place to start looking for information," Santerre says. "We recently added a short video on proper fish cleaning." Other research institutions involved in the study are: University of Georgia, University of Florida, Tennessee Technological University, Auburn University, Texas A&M University, Louisiana State University, Mississippi State University and North Carolina State University. Source: Charles Santerre, (765) 496-3443, santerre@cfs.purdue.edu Writer: Susan Gaidos, (765) 494-2081; sgaidos@purdue.edu NOTE TO JOURNALISTS: A copy of the study is available from Susan Gaidos, (765) 494-2081, sgaidos@purdue.edu. ABSTRACT Metal Residues in Farm-Raised Channel Catfish, C.R. Santerre, P.B. Bush, D.H. Xu, G.W. Lewis, Farm-raised channel catfish, rainbow trout and red swamp crayfish were collected from production and processing sites across the southern United States and analyzed for barium, cadmium, copper, chromium, silver, lead, arsenic, selenium and mercury. Average metal residues were much lower than recommended safety limits. Residues of barium, copper and mercury were slightly higher in crayfish than catfish or trout. Selenium was higher in crayfish and trout than catfish, and lead was higher in catfish and trout than crayfish. Residues of mercury in all samples were much lower than the FDA's Action Limit (one part per million) for mercury in the edible tissue of fish.
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