Reducing Environmental Pollutants Tied to Drop in Diabetes

Becky McCall

November 01, 2016

Lowering exposure to endocrine-disrupting chemicals (EDCs) would reduce the burden of adult diabetes by approximately 13% and save around €4.51 billion/year in costs, according to data from a study in the European elderly population.

A 25% reduction in four EDCs, analyzed in aggregate, was associated with a 13% (95% CI, 2% – 22%) lower prevalence of diabetes, or 152,481 fewer cases per year across Europe, according to Leonardo Trasande, MD, from New York University School of Medicine, and colleagues. In comparison, a 25% reduction in body mass index (BMI) would be expected to reduce diabetes prevalence by 40%, or 469,172 fewer cases per year.

Building on prior work, this study looked at the effects of pollutants in aggregate and individually, as well as disease-related costs saved if exposures were reduced. "The reality is that we don't live in a single chemical soup, but in a world of mixtures of these environmental chemicals," Dr Trasande told Medscape Medical News.

"These epidemiological findings are likely to be causal, since they are in line with experimental mechanistic data," write the authors in the paper published online October 27 in the Journal of Epidemiology & Community Health.

Multiple synthetic chemicals are thought to contribute to metabolic disorders, especially obesity and diabetes, and in particular, this study examined four EDCs found to be significant in isolation — phthalates; dichlorodiphenyltrichloroethylene (DDE); polychlorinated biphenyls (PCBs); and perfluoroalkyl substances. Dr Trasande noted that this study is the first to simultaneously examine multiple EDCs, which are known to coexist in the environment.

Bruce Blumberg, PhD, professor of developmental and cell biology, University of California, Irvine, leads research on how exposure to EDCs can induce permanent physiological changes. Asked to comment on the work, he acknowledged that the findings of the study were significant and indicated that EDCs are likely to contribute to the development of diabetes in the elderly. However, he emphasized that "the chemicals studied represent the tip of the iceberg because, as we found previously, the types of data required to establish causation between exposure to one of the more than 1000 known or suspected EDCs and disease outcomes in humans are currently lacking in most cases" (J Clin Endocrinol Metab. 2015;100:1278–1288).

The current study used data from a population-based cohort known as the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, which measured persistent and nonpersistent chemical exposures to examine their independent contribution to diabetes. Participants were aged 70 years and living in the city of Uppsala, Sweden. The researchers modeled estimated diabetes risk reductions assuming identical 25% reductions across levels of the four selected compounds, as well as a similar reduction in BMI.

Reflecting on the use of a population aged 70 years, Dr Trasande said that diabetes is prevalent in an age-dependent relationship and that exposures to persistent organic pollutants were substantial in these populations. "In these people, the antecedent exposures would be important."

Aggregate Effect of a Chemical Mixture

Despite relatively modest sample sizes, Dr Trasande said there was a strong directionality in the results, with the most marked decrease in disease burden seen when the EDCs were reduced in aggregate.

"This suggests that single chemical exposures don't necessarily act in isolation in contribution to metabolic disruption, but it is the mixture of however many chemicals that actually contribute to diabetes and obesity."

Dr Trasande also stressed their other major finding: There were substantial economic benefits to proactive measures to prevent exposures that may contribute to diabetes and obesity in highly vulnerable populations. "This reinforces the need for proactive regulation of EDCs in Europe and beyond. It also reinforces the need for further provision of guidance on behalf of prevention, based on the fact that these exposures are preventable with diet change and other behavioral changes."

He also remarked that although diet and physical activity are considered the major drivers of the global "diabesity" epidemic, "substantial chemical exposures are also major contributors independent of diet and physical activity."

Regulation of EDCs in the US and EU

The authors write that PCBs have already been banned under the Stockholm Convention. The pesticide DDE has also been banned in most parts of the world. A voluntary phase-out of long-chain perfluoroalkyl compounds, including perfluorononanoic acid (PFNA), has been completed in the United States.

However, regulatory authorities in the United States and the European Union are certainly not doing enough to address the concerns raised by the large and growing body of scientific evidence, according to Dr Blumberg. He said this was largely due to a disinformation campaign waged by industry and industry-sympathetic/supported scientists who are manufacturing doubt about the evidence. "This is much as they previously did for tobacco, secondhand smoke, acid rain, and global climate change, to name a few. This manufactured doubt leads to regulatory inaction. While the truth will eventually win out, the public interest is not served by how the process currently works."

He added that consumers had good reason to be concerned. "They should not assume that government regulators are acting to protect their health and well-being or that the chemicals in commerce have been fully vetted for adverse health effects, particularly for endocrine-disrupting effects."

Also commenting on the new study, Barbara Demeneix, PhD, professor at the laboratory of evolution of endocrine regulation, Natural History Museum, Paris, France, remarked that research was "well done and, as usual for Leonard Trasande's work, the estimates are realistic. The authors recognize the stronger causal influence of BMI but identify another means of reducing disease burden and costs through better advice and regulation."

Dr Trasande said that further research was clearly needed to sort out the degree and strength of epidemiologic associations and to assess the associations identified in younger populations. "While there remains some uncertainty, the data suggest substantial probability of causation and call for action."

Dr Trasande declares no relevant financial relationships. Dr Blumberg previously received a grant from the Swedish Environment Agency, FORMAS, with Monica Lind, senior author on the current paper. Dr Demeneix is cofounder of www.watchfrog.fr.

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J Epidemiol Community Health. Published online October 27, 2016. Article

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