Persistent Organic Pollutants Linked to Type 2 Diabetes

(Beyond Pesticides, July 5, 2011)

Recent findings add to a growing body of evidence that persistent organic pollutants (POPs) might drive changes in the body that lead to diabetes, researchers say. A new study finds that environmental exposure to some POPs substantially increased risk of future type 2 diabetes in an elderly population.

Persistent organic pollutants (POPs) are lipophilic (fat-loving) chemicals that accumulate mainly in adipose tissue and have recently been linked to type 2 diabetes. This current study, “Polychlorinated Biphenyls and Organochlorine Pesticides in Plasma Predict Development of Type 2 Diabetes in the Elderly: The Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) Study,” sought to follow up on previous findings that had linked these chemicals with type 2 diabetes and was performed to evaluate prospective associations of type 2 diabetes with selected POPs among the elderly. The team recruited a group of 725 diabetes-free elderly adults in Sweden and took blood samples to measure their levels of the pollutants. Then, the researchers followed them for the next five years. Thirty-six of the study participants were diagnosed with type 2 diabetes over that time. Nineteen POPs (14 polychlorinated biphenyl [PCB] congeners, 3 organochlorine pesticides, 1 brominated diphenyl ether, and 1 dioxin) were measured in plasma collected at baseline of the participants, aged 70 years. Those who had high levels of PCBs were up to nine times more likely to get diabetes than those with very low pollutant levels in their blood. Those exposed to organochlorine pesticides were up to three times as likely to develop type 2 diabetes.

The pollutants, including the pesticides and poly-chlorinated biphenyl are largely found in meat and fatty fish. According to one of the researchers, Duk-Hee Lee, PhD, “The exposure to these chemicals in the general population still occurs because they have widely contaminated our food chain.” While the authors of this study note that the number of new diabetes cases is low, research suggesting that POPs are linked to the onset of type 2 diabetes is mounting.

More than eight percent of the U.S. population has diabetes, according to the National Institutes of Health, most of them type 2 diabetes. Many studies have linked type 2 diabetes to overweight, lack of exercise and high blood pressure. In this new study, a big waistline is also a diabetes risk factor. The authors speculate that long-term exposure to environmental pollutants could affect cells in the pancreas that secrete insulin, a hormone that regulates blood sugar. It would make sense that heavier people are more at risk of diabetes because they’re also probably eating more fatty meat and fish high in these chemicals, and they have more fat themselves where these chemicals are stored.

Persistent organic pollutants (POPs) are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of this, they have been observed to persist in the environment, to be capable of long-range transport, bioaccumulate in human and animal tissue, biomagnify in food chains, and to have potential significant impacts on human health and the environment. Many POPs are currently or were in the past used as pesticides. Others are used in industrial processes and in the production of a range of goods such as solvents, polyvinyl chloride, and pharmaceuticals. The Stockholm Convention on Persistent Organic Pollutants is an international environmental treaty that aims to eliminate or restrict the production and use of persistent organic pollutants (POPs).

The study illustrates how the health impacts of pesticides are often subtle and delayed, and pesticides once considered to pose “acceptable” risks are continuing to affect public health. In response to the growing evidence linking pesticide exposures to numerous human health effects, Beyond Pesticides launched the Pesticide-Induced Diseases Database to capture the range of diseases linked to pesticides through epidemiologic studies. The database, which currently contains hundreds of entries of epidemiologic and laboratory exposure studies, will be continually updated to track the emerging findings and trends.

To address this issue, Beyond Pesticides has called for alternatives assessment in environmental rulemaking that creates a regulatory trigger to adopt alternatives and drive the market to go green. The alternatives assessment approach differs most dramatically from risk assessment in rejecting uses and exposures deemed acceptable under risk assessment calculations, but unnecessary because of the availability of safer alternatives. For example, in agriculture, where the database shows clear links to pesticide use and multiple types of cancer, it would no longer be possible to use hazardous pesticides, as it is with risk assessment-based policy, when there are clearly effective organic systems with competitive yields that, in fact, outperform chemical-intensive agriculture in drought years. This same analysis can be applied to home and garden use of pesticides where households using pesticides suffer elevated rates of cancer.