12 March 2014

More than 40 years after a major spill of PCBs, a toxic environmental contaminant, these can still be traced in the bloodstream of exposed people. Particularly high levels of PCBs have been measured in the lipoproteins of people with cancer and cardiovascular disease, according to researchers at Linköping University.

In 1972 large volumes of PCBs, polychlorinated biphenyl, were released into a waterway in Gusum, a mill town in southeastern Sweden. The chemical, which was formerly used as an insulator in electrical equipment and a softener in plastics and sealants, is banned in Sweden. It belongs to the group of long-lasting organic compounds that biodegrade very slowly. In humans and animals they can be stored in body fat and transform into other chemicals.

In an interdisciplinary study, researchers at Linköping University’s Occupational and Environmental Medicine, in collaboration with colleagues at Örebro University, analysed the occurrence of these compounds in people who have lived in the polluted area. The studies show a clear correlation between high levels of the particles - lipoproteins - that transport cholesterol in the blood and the occurrence of cancer and cardiovascular disease. The results were recently published in the scientific journal Environment International.

First to demonstrate correlation

“We’re the first to demonstrate this correlation in a population study where we have data from questionnaires and links to the individuals’ medical history,” says doctoral student and first author Stefan Ljunggren.

The study included 78 people who had previously answered questions about their lifestyle. When the researchers compared the questionnaire responses, there was a correlation between cancer and high consumption of locally caught perch, pike and zander. Previous tests had shown that these fish had high concentrations of PCB.

The lipoproteins LDL and HDL occur in the bloodstream, where their job is to transport fat to and from the body cells. In the study, high levels of PCB in LDL are linked to cancer, while high levels in HDL are associated with cardiovascular disease. Because the environmental toxin are fat soluble, it is possible that they can be absorbed in cells via the cholesterol particles, and have an effect on the genetic level.

Helen Karlsson, environmental chemist and co-author, sees the study as an example of how mapping of polluted areas in combination with epidemiological studies can be followed up with in-depth biochemical analyses.

“An interdisciplinary collaboration like this ensures better information for risk assessment, and an increased understanding of how environmental pollutants affect the human body.”

Article: Persistent Organic Pollutants Distribution in Lipoprotein Fractions in Relation to Cardiovascular Disease and Cancer, by S Ljunggren, I Helmfrid, S Salihovic, B van Bavel, G Wingren, M Lindahl and H Karlsson. Environment International vol. 65, 2014.