The Korean and American researchers behind the study say it suggests a link between POP exposure and diabetes.
Studies on laboratory animals have indicated several contaminants - including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and the plastic intermediate bisphenol A - increase the incidence of diabetes (ENDS Report 374, p 25 ). A link has also been established for people with high levels of occupational exposure: for instance, Vietnam veterans exposed to TCDD through Agent Orange.
In this case researchers analysed data on 2,000 members of the general public under the Centers for Disease Control and Prevention’s biomonitoring programme the National Health and Nutrition Examination Survey (ENDS Report 374, pp 26-29 ).
They divided the individuals into five groups based on the concentration in their blood of six common persistent organic pollutants: PCB 153, two dioxin congeners, the pesticides oxychlordane and trans-nonachlor, and the DDT metabolite p,p’-DDE.
Even when results were normalised to account for other factors such as obesity, the group with the highest POP levels had a diabetes risk 38 times higher those with the lowest POP levels.
Indeed, the same pattern, if less marked, was found once the sample was split into sub-groups based on body mass index. The link was clearer in the more obese subjects, leading the researchers to suggest that as people get fatter, their retention and the toxicity of POPs increases.
They admit it is possible that none of the POPs studied is responsible for diabetes. It may be that their presence indicates that of another substance which is directly responsible.