What is diabetes?
Diabetes is a group of metabolic diseases in which a person’s blood sugar levels are too high, caused by failure of the body to either produce insulin (type-1 diabetes) or respond to it (type-2 diabetes). It is becoming increasingly common, with 11 per cent of Americans over 20 years of age now estimated to have the disease.
Type-1 diabetes normally develops in childhood as the result of an autoimmune disorder where the body destroys its own insulin-producing cells. Type-2 diabetes usually develops in adults, although the age at which it develops is coming down (Koopman et al. 2005).
The rise in incidence of type-2 diabetes is generally attributed to an aging population and changes in modern lifestyle such as reduced physical activity and eating more foods high in animal fats. However, researchers are beginning to find consistent correlations between increased risk of type-2 diabetes and exposure to persistent organic pollutants (POPs) such as DDT, PCBs and dioxins (Carpenter 2008, Lee et al. 2010).
Because diabetes is an autoimmune disease, can be brought on by obesity, and is a disorder of insulin resistance, then any chemicals which contribute in some way to increased risk of any of these problems may also be contributing in some way to increasing rates of diabetes. Animal studies are showing links between a range of chemicals in the environment and the development of these problems.
Which chemicals are a problem?
Contaminants associated with diabetes in humans include some air pollutants, nitrate/nitrite/N-nitroso compounds, bisphenol A, cadmium, some pesticides, some persistent organic pollutants (including dioxin and PCBs), some flame retardants, selenium and phthalates (Thayer et al 2012).
Some air pollutants, bisphenol A, some persistent organic pollutants (including PCBs) and some pesticides have been found to promote insulin resistance in animals. Air pollutants, bisphenol A, some persistent organic pollutants (including PCBs), some phthalates, some heavy metals, some pesticides and solvents have been found to increase weight gain in animals.
Since many of these chemicals, especially PCBs, flame retardants and dioxins, are produced in electronics waste streams, reducing the use of chlorinated plastics and halogenated compounds is important in electronic goods.
Chemicals as an emerging risk factor in developing type-2 diabetes: a short history. An account of how evidence has emerged in the last 10 years connecting exposure to background levels of POPs and risk of onset of type-2 diabetes.
Two New Reasons to Worry about Air Pollution: Obesity and Diabetes. Forbes covers the controversy over the decision in the US to delay imposition of smog controls, in the context of concern that air pollution may increase risk of obesity and diabetes, two of the biggest public health issues the country faces.
Selection of references
Carpenter DO. Environmental contaminants as risk factors for developing diabetes. Rev Environ Health. 2008 Jan-Mar;23(1):59-74. Review. PubMed PMID:18557598.
Lee DH, Steffes MW, Sjödin A, Jones RS, Needham LL, Jacobs DR Jr. Low dose of some persistent organic pollutants predicts type 2 diabetes: a nested case-control study. Environ Health Perspect. 2010 Sep;118(9):1235-42. Epub 2010 May 5. PubMed PMID: 20444671; PubMed Central PMCID: PMC2944083.
Koopman RJ, Mainous AG 3rd, Diaz VA, Geesey ME. Changes in age at diagnosis of type 2 diabetes mellitus in the United States, 1988 to 2000. Ann Fam Med. 2005 Jan-Feb;3(1):60-3. PubMed PMID: 15671192; PubMed Central PMCID: PMC1466782.
Thayer KA, Heindel JJ, Bucher JR, Gallo MA. Role of Environmental Chemicals in Diabetes and Obesity: A National Toxicology Program Workshop Report. Environ Health Perspect. 2012 Feb 1. [Epub ahead of print] PubMed PMID: 22296744.
US Department of Health and Human Services. National Diabetes Statistics 2011. Retrieved 24 February 2012 from http://diabetes.niddk.nih.gov/DM/PUBS/statistics/.