Exposure to high levels of environmental pollutants may increase the risk of type 2 diabetes, according to a new study.

Previous studies linked exposure to organo-chlorine pollutants (POPs) with asthma, diabetes and many types of cancer.

The current study, conducted by researchers from the University of Lund in Sweden, found diabetics were more likely to have high levels of POPs such as polychlorinated biphenyls (PCBs) and the insecticide dichloro-diphenyl-trichloro-ethane or DDT in their blood.

Researchers suspected that oily fish such as salmon, which is often contaminated with pollutants such as dioxin and PCBs, may be an important source of contamination that attributes to the development of diabetes. Therefore, they carried out the study to determine if there was any association between serum pollutants and diabetes.

The study involved 196 fishermen and their spouses. Blood samples from the participants were analyzed for a POP residue known as CB-153, a biomarker of PCBs, and DDE, the main by-product of DDT.

It was found that six percent of men and five percent of their wives who had type 2 diabetes had high concentrations of both chemicals.

The finding echoed previous studies which established an association between exposure to PCBs and/or to DDT, and incidence of diabetes.

Photo by Stephen Ausmus

Although the current study could not determine whether diabetes in the subjects with high levels of contamination was caused by PCBs and or DDT, previous studies indicate such a causal relationship might exist.

One such study, involving 2,245 pregnant women, was authored by Matthew P. Longnecker at National Institute of Environmental Health Sciences and colleagues and published in the June, 2001 issue of Diabetes Care.

"The adjusted mean serum level of PCBs among the subjects with diabetes was 30% higher than in the control subjects, and the relationship of PCB level to adjusted odds of diabetes was linear," the authors write in their article.

Exposure to the insecticide DDT, first used in the 1950s, has also been linked to an increased risk of diabetes. One study considering the effect of DDT was conducted by John Beard and colleagues from Southern Cross University in Australia and published in the May, 2003 issue of Environmental Health Perspectives.

The study found on-job exposure to DDT and other pesticides were associated with asthma and pancreatic cancer in addition to diabetes.

PCBs were widely used as a flame retardant in many industrial and household products such as TV, computers, carpets, apparels, furniture or wherever fire needs to be prevented. They were banned in the 1970s because of their toxicity. DDT was also banned for its toxicity. However, they, along with a company of other pollutants, are still present in the environment and many people's blood.

The results of the current study did not suggest people should stop eating fish. The subjects lived near a sea where pollutants may be easy to accumulate in fish. That is why they tend to have a high level of pollutants in their blood.

Fish is an important part of a healthy diet and the US government recommends regularly eating a variety of fish. However, consumers should read fish consumption advisories posted by the federal and state governments for the fish safety information.

Environmental Working Group also has plenty of fish safety information.

For more information on fish contamination and flame-retardants, visit the Web site Environmental Working Group.

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