What are PCBs, and why are higher levels found in farmed salmon?
Polychlorinated Biphenyls, or PCBs, are persistent, cancer-causing chemicals that were widely used from the 1930s to the 1970s and are now banned from North America. Polybrominated diphenyl ethers or PBDEs, are chemical fire retardants used in several products and are found in the environment. A study published in the American journal Environmental Science and Technology on August 10, 2004 found on average higher levels of PCBs in farmed salmon than in wild salmon. The authors of the study concluded that frequent consumption of farmed salmon is more likely to boost exposure to PBDEs than wild salmon. The economic incentive to speed the growth of farmed species has led to the use of an increasingly high-energy diet, which means farmed salmon have a higher fat content than their wild counterparts. This makes them more vulnerable to contamination by fat-soluble pollutants (i.e. PCBs) that accumulate up the food chain. And, since feed ingredients are sourced from fisheries all over the wor
