stressed heartENEWSPF, Washington DC, 14 October 2011

Researchers at Uppsala University in Sweden have found that environmental toxicants such as dioxins, PCBs, and pesticides can pose a risk for cardiovascular disease. 

The results of the study, entitled "Circulating Levels of Persistent Organic Pollutants (POPs) and Carotid Atherosclerosis in the Elderly," show a link between exposure to persistent organic pollutants (POPs), including several organochlorine pesticides, and the development of atherosclerosis, which can lead to heart disease. The study will be published in the journal Environmental Health Perspectives, and a version of it is available online ahead of print.

Cardiovascular diseases, including heart attacks and strokes, are the most common cause of death in industrialized countries, and the most important underlying cause of these diseases is atherosclerosis. Unbalanced blood fats, diabetes, smoking, and high blood pressure are traditionally recognized risk factors for atherosclerosis.

Previous studies have also reported possible links between cardiovascular disease and high levels of persistent (long-lived and hard-to-degrade) organic environmental toxicants, such as dioxins, polychlorinated biphenyls (PCBs), and pesticides. These compounds are fat-soluble and can therefore accumulate in vessel walls. However, no earlier studies have investigated possible links between exposure to these compounds and atherosclerosis.

Of the POPs that were screened for, five were pesticides or pesticide degradates: hexachlorobenzene, three chlordane-related compounds, and DDE, a close relative and degradate of DDT. As previous research has demonstrated, although some of these chemicals have long since been banned in the United States, their persistence remains so high that they are still routinely detected in human tissue. Other highly persistent toxic compounds remain on the market today, including many pesticide chemicals.

Persistent organic pollutants are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes. Because of this, they persist in the environment, are capable of long-range transport, bioaccumulate in human and animal tissue, biomagnify in food chains, and 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 POPs.

The current study measured the circulating levels of the above group of compounds in about 1,000 Swedes living in Uppsala. Atherosclerosis in the carotid artery was also measured using ultrasound. The findings show a clear connection between increasing levels of environmental toxicants and atherosclerosis, even after taking into consideration the traditional risk factors. There was also a link to tangible signs of fat accumulation in vessel walls.

"These findings indicate that long-lived organic environmental toxicants may be involved in the occurrence of atherosclerosis and thereby lead to future death from cardiovascular diseases," says Lars Lind, PhD., professor at the Department of Medical Sciences, Uppsala University.

"In Sweden, and in many countries in the world, many of these substances are forbidden today, but since they are so long-lived they're still out there in our environment. We ingest these environmental toxicants with the food we eat, and since they are stored in our bodies, the levels grow higher the older we get," says Monica Lind, PhD., Associate Professor in Environmental Medicine at Occupational and Environmental Medicine.

Organochlorine pesticides have previously been linked to a number of adverse effects on human health including birth defects and diabetes. This study illustrates how the health impacts of pesticides can be 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, is continually updated to track the emerging findings and trends.