Adding to China's recent problems of food safety is now seafood contamination. As the world's largest producer and exporter of fish and fish products, China may need to more closely monitor shellfish contaminant levels, because contaminants are finding their way into seafood. A new study found samples from markets that contained concentrations of contaminants high enough to pose threats to human health. The study is published in the latest issue of Environmental Toxicology and Chemistry.
Organochlorine pesticides such as DDT can accumulate in top predators, including humans. Though these pesticides were officially banned in 1983, China had been using them for decades prior to the ban. Twenty-five years later, there is evidence that new sources, particularly of DDT, may be present and contaminating seafood.
The current study focused on seafood from markets in 11 coastal cities in Guangdong Province. The last two decades have witnessed explosive economic growth in that province. Rapid industrialization, urbanization, and conversion of agricultural lands to commercial use have accelerated the environmental deterioration in this region.
Samples of shrimps, crabs, and mollusks were analyzed for 21 organochlorine pesticides. Of those, DDT and HCH (hexachlorocyclohexane) were detected most frequently and measured at the highest concentrations. These highest concentrations were observed in mollusks, specifically oysters, mussels, and squid. Concentrations of DDT in some of this seafood were high enough to pose human health threats. Other organochlorine pesticides present were at concentrations high enough to pose human cancer risks.
The study's researchers said further research was urgently required to identify the new sources of organochlorine pesticide contamination, so the food safety issues could be dealt with. Human health risk assessments are required to determine potential risks from local and overseas consumption and potential limits that should be imposed on such consumption.
China exports 3.2 million metric tons of seafood products, which is 10 percent of the global export volume. Exports primarily go to Japan, Korea, Canada, the United States, and the European Union.