Endocrine-disrupting chemicals – substances or mixtures that alter the function of the endocrine system in an unhealthy way – are found everywhere on our planet, exposing many living things, including people, to possible harm. These include a wide variety of chemicals, such as pesticides, environmental pollutants and compounds or components used in the plastics industry and in consumer products.

As an endocrinologist, I consider the environmental factors that may affect our body, including EDCs. These powerful, small particles can interfere with many important physiological steps like the production, transportation and elimination of hormones; they can even mimic the natural hormones that our body makes.

The concept of EDCs started emerging about 20 years ago, if not earlier. In 2012, the United Nations Environment Programme and the World Health Organization produced a 296-page scientific report compiling what's known about EDC exposure and the chemicals' effects. I find the possible link between EDCs, metabolism and diabetes fascinating. Other than diet and physical activity, what are the other factors that affect our metabolism? Can EDCs be linked to the global diabetes epidemic?

Diabetes is a disease caused by too much sugar in the blood, also known as high blood glucose. Estrogen, a group of hormones that are responsible for female sexual development and function, and other sex hormones are known for regulating the reproductive system. However, they also play a fundamental role in behavior, bone development and immunity, as well as glucose metabolism.

There is growing evidence that during critical periods of embryonic development, estrogenic compounds from EDCs could cause permanent changes by influencing gene expression, which can then affect metabolism. Considering that estrogen hormones are key regulators of glucose levels, since they help balance energy and play an important role in insulin production, how do EDCs' estrogenic properties contribute to the dramatic rise in obesity, Type 2 diabetes and metabolic syndrome – a cluster of issues, from high blood pressure to high blood sugar, that increases a person's risk for heart disease and other health problems?

Some EDCs remain in the body for a very long time. In fact, animal studies have shown that their long-term effect can be seen through many generations, such as with certain pesticides like DDT, or dichlorodiphenyltrichloroethane, environmental pollutants called dioxins and heavy metals.

Results from animal experiments have demonstrated that exposure to EDCs can change glucose levels in the mothers and their offspring, when they become adults.

Some of the studies suggest that oral exposure to the chemical bisphenol A, or BPA, during pregnancy and lactation increased body weight in adult offspring. Indeed, the effects of these EDCs mimic a high-fat diet in changing the glucose and lipid metabolism. Even short-term BPA exposure during pregnancy affected metabolic programming – weight and glucose metabolism – in the offspring later in life, as well as the metabolic state of the mother in the long term.

The results of experiments looking at exposure to BPA around the time of a baby's birth are controversial. However, the capacity of EDCs to possibly change gene expression, which may persist throughout life, makes their impact on human and nature even more influential.

Although most of the research is from animal studies, some data linking diabetes to environmental pollutants come from studies performed on people following accidental releases of EDCs. For example, a chemical plant explosion in Seveso, Italy in the summer of 1976 released a cloud of dioxin. Several years after this environmental disaster, follow-up studies showed an increased risk of diabetes in those exposed to the chemicals, especially women. Studies focused on military personnel exposed to Herbicide Orange, or Agent Orange, during the Vietnam War revealed the same association, with higher rates of Type 2 diabetes in those exposed to the chemicals.

We also have information about EDC exposure and diabetes in the general population, mainly from the National Health and Nutrition Examination Survey, a food consumption database program founded in the 1960s to assess the health and nutritional status of adults and children across the U.S. Around the late 1990s, blood and urine tests for some chemicals were included in the survey. Results have shown that most participants have detectable blood and/or urine levels of several chemicals – in particular, BPA – and that diabetes, whether diagnosed or self-reported, is strongly associated with exposure to some of the EDCs.

The evidence presented should be considered with caution. Even though a systematic review of information from around the world has recently suggested an association between diabetes or prediabetes and EDC exposure, the research has its limitations. Furthermore, an association between EDC exposure and diabetes does not necessarily establish exposure to the chemicals causes the disease.

While genetic predisposition and environmental factors, such as diet and exercise, play key roles in Type 2 diabetes, this emerging information about the potential effects of EDC exposure should be kept in mind.

The possible impact of EDCs on our health is not limited to diabetes. A recent opinion article published in the New England Journal of Medicine focuses on genetically modified organisms, or GMOs, herbicides and public health. Personally, I often think about how my grandmother's exposure to a pesticide used to fight malaria during the 1940s might have affected my family, possibly disrupting my son's neurodevelopment.