PCBs and Obesity

We and others have shown relationships between circulating levels of persistent organic pollutants (POPs) and different measures of obesity in both cross-sectional and prospective studies. Since viscerally located fat seems to be the most harmful type, we investigated whether plasma POP levels were more closely related to visceral adipose tissue (VAT) than to subcutaneous adipose tissue (SAT). Thousand hundred and sixteen subjects aged 70 years were investigated in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study; 23 POPs were analyzed using high-resolution gas chromatography/high-resolution mass spectrometry. Abdominal magnetic resonance imaging, measuring VAT and SAT, respectively, was performed in a representative subsample of 287 subjects. The less chlorinated polychlorinated biphenyl (PCB) congeners (105 and 118), and the pesticides dichlorodiphenyldichloroethylene (DDE), hexachlorobenzene (HCB), and trans-nonachlordane (TNC) were positively related to both VAT and SAT, whereas the more highly chlorinated PCBs (153, 156, 157, 169, 170, 180, 194, 206, and 209) were inversely related to both VAT and SAT. PCB189 was related to the VAT/SAT ratio in an inverted U-shaped manner (P = 0.0008). In conclusion, the results were in accordance with our previous studies using waist circumference and fat mass as obesity measure. However, the novel finding that PCB189 was related to the VAT/SAT ratio deserves further investigation since exposure to this PCB congener, which has previously been linked to diabetes development, might thereby play a role in the distribution of abdominal adipose tissue.

From press release:

There is a correlation between high levels of the environmental toxin PCB and the distribution of body fat to the abdomen. This is shown in a new study published May 29 in the scientific journal Obesity. Abdominal fat is already known to increase the risk of diabetes and high blood pressure, among other conditions.


Fat inside the abdomen (visceral fat) is considerably more dangerous that fat near the surface of the body (subcutaneous fat). For instance, fat in the abdomen has previously been linked to the development of diabetes. Monica Lind, associate professor in environmental medicine at the Section for Occupational and Environmental Medicine, together with Lars Lind, professor of medicine, has analysed data from the so-called PIVUS study, which comprises more than 1,000 70-year-olds in Uppsala.

From the same material they have previously shown that PCB can predict the development of diabetes. In the present study, these researchers measured levels in the blood of 23 persistent organic environmental toxins in the more than 1,000 70-year-old women and men. In nearly 300 of them, with the aid of magnetic imaging, they also investigated the amount of fat in various parts of the abdomen. Previous studies have used only BMI as a measure of fatness. They found that having high levels of the highly chlorinated and very persistent compound PCB189 was related to a high proportion of fat in the abdomen.

"These findings may indicate that PCB189, which was also related to developing diabetes, may be of significance in how fat is stored in the body," says Monica Lind.

To understand the underlying mechanism, more research is needed in the form of controlled laboratory studies. According to Monica Lind, there are several possible causes. For example, it would be interesting to study whether there is a hormonal impact on fat metabolism, an inhibition of the breakdown of cortisol, or an inhibition of the creation of oestrogen.