New report: “Review of the Science Linking Chemical Exposures to the Human Risk of Obesity and Diabetes”

Sarah Howard
Coordinator of the CHE Diabetes and Obesity Spectrum Working Group

The UK nonprofit organization CHEM Trust (Chemicals, Health and Environment Monitoring Trust) just released a report on the links between chemicals and diabetes/obesity. Studies published in recent years provide compelling evidence that human chemical contamination can play a part in both conditions. The report concludes that the chemicals that we accumulate throughout life, via our everyday lifestyles, is likely to contribute to these modern epidemics. This is the same conclusion reached by the National Toxicology Program’s review of the scientific evidence on chemicals and diabetes/obesity, published last month.  

The CHEM Trust report, entitled Review of the Science Linking Chemical Exposures to the Human Risk of Obesity and Diabetes, is written by two of the world’s leading experts: Professor Miquel Porta, MD, MPH, PhD, of Spain and Professor Duk-Hee Lee, MD, PhD, of South Korea.

The report focuses on endocrine disrupting chemicals in both obesity and diabetes. Exposures to these chemicals in the womb, at other critical periods of life, and in adulthood may be linked to obesity and disruption of the normal functioning of insulin in later life. Evidence of the role of hormone disrupting chemicals comes from both laboratory studies and studies on human populations.

In one example, the report describes a study from the general US population that found that persistent organic pollutants (POPs) in fatty tissue, even more than the fat itself, plays a critical role in the development of diabetes. People who were obese did not have an increased risk of diabetes if their levels of POPs were low. People who were thin did have a higher risk of diabetes if their POP levels were higher. And those with higher POP levels who were also obese had the highest diabetes risk of all.

The chemicals suspected of increasing weight gain or diabetes in humans include a variety of chemicals, including numerous POPs, arsenic, BPA, phthalates, pesticides (including atrazine, organophosphorous and organochlorine pesticides), brominated flame retardants, metals (including cadmium, mercury, organotins), and more. Many of these are endocrine disrupting chemicals (EDCs), and have the ability to disrupt our natural hormones which control both fat storage and blood sugar regulation, and hence can play a role in obesity and diabetes.

Professor Miquel Porta stated, “The epidemics in obesity and diabetes are extremely worrying. The role of hormone disrupting chemicals in this must be addressed. The number of such chemicals that contaminate humans is considerable. We must encourage new policies that help minimize human exposure to all relevant hormone disruptors, especially women planning pregnancy, as it appears to be the fetus developing in utero that is at greatest risk.”

Elizabeth Salter Green, CHEM Trust Director stated, “If exposure to hormone disrupting chemicals is programming us to be fat, it is high time that public health policy takes into account cutting edge science. Obesity and diabetes are examples of the adverse health trends linked with endocrine disruption which need to be urgently addressed. We are talking about prevention, and in this time of financial squeeze, anything that can help with prevention is a good idea. CHEM Trust is calling for the UK Government and the EU to urgently identify hormone disruptors to ensure that chemicals suspected of playing a role in diabetes and obesity are substituted with safer alternatives.”

Summary of the report’s conclusions

• Studies suggest that exposure to certain chemicals in the environment can play an important role in obesity and diabetes. The chemicals implicated include some to which the general population are exposed on a daily basis.
• Substantial evidence exists to consider exposure to EDCs with estrogenic activity as a risk factor for the etiology of obesity and obesity-related metabolic dysfunction.
• Evidence suggesting a relationship between human contamination with environmental chemicals and the risk of diabetes has existed for more than 15 years, with the volume and strength of evidence becoming particularly persuasive since 2006.
• Obesity is a known risk factor for diabetes, and chemicals that accumulate in body fat (e.g., POPs) may play a role in the causal relationship between obesity and diabetes.
• Many of the chemicals that can cause weight gain and related metabolic effects have endocrine disrupting properties.
• Embryonic, fetal, and infantile stages may be especially vulnerable to obesity from relatively low doses of EDCs. Nonetheless, the risk of obesity due to obesogenic pollutants can also increase during adolescence and adulthood.

Summary of the report’s recommendations

• Action to reduce exposures to such chemicals is warranted on a precautionary basis, and is likely to be cost-effective.
• National governments and the EU need to urgently put forward mechanisms to identify EDCs to ensure that currently used chemicals suspected of playing a role in obesity and diabetes are substituted with safer alternatives.
• Health professionals, citizens’ organisations, companies, authorities and society at large need to be better informed of the role that chemical exposures may play in causing diabetes and obesity.
• Individuals, industry, the agricultural sector, dieticians and the medical professions all have roles to play in reducing exposures both in the home and in occupational settings.
• Personal changes in lifestyle are certainly important for the prevention of obesity and diabetes, but this should not obscure the need for government policies within and outside the health sector to decrease human exposure to obesogenic and diabetogenic environmental compounds.
• As many of the chemicals implicated widely contaminate the animal and human food chains and some are also released from some food containers, dietary interventions ignoring the presence of contaminants in food may hamper the expected beneficial effects of dietary recommendations.
• In order to protect fetuses and newborn babies, specific advice is needed for pregnant women and midwives regarding EDCs in the diet and in consumer products used by pregnant women and/or babies.
• Public health policies, including those seeking to reduce exposure to suspect chemicals, need to be implemented swiftly. To preserve quality of life, prevention in both cases is vastly preferable to treatment.
• Evidence for the association between exposure to EDCs and obesity should lead to a paradigm shift in how to tackle obesity. The focus should be broadened from one based on individual lifestyle, diagnosis and treatment to one that includes population prevention measures.
• Population-based biomonitoring must be strengthened to provide a better understanding of the extent of human contamination by environmental obesogens and diabetogens in the general population.
• Progress is also needed in identifying the sources of exposure (e.g., which food products, which consumer products). Further research is particularly warranted on the role that food additives, contaminants in animal feed and human food, and packaging may play in obesity and diabetes.
• Screens and tests to identify chemicals that can impact on obesity and diabetes should be developed, and certain chemicals should be required to undergo such testing.
• More attention should be given to protecting populations in the developing world from exposure to environmental pollutants, including that arising from electronic waste, food contamination, air pollution and the erroneous use of certain pesticides.

CHEM Trust’s goal is to protect humans and wildlife from harmful chemicals. They have published previous reports on chemicals and the developing brain, breast cancer, reproductive health, and more.

This report as well as others are available at the CHEM Trust website.

CHE has a working group on diabetes and obesity for those interested in this topic. To join, please email info@healthandenvironment.org.