Chemical pollutants: An invisible cause of obesity? | World Obesity Federation

Chemical pollutants: An invisible cause of obesity?

NewsChemical pollutants: An invisible cause of obesity?

Persistent chemicals in the environment may be adding to the obesity epidemic and, says Dr Tim Lobstein, are another reason why individuals should not be blamed for weight gain.

In 2002 a paper in the Journal of Alternative and Complementary Medicine suggested that the obesity epidemic that had emerged in the preceding two decades in developed economies may be linked to exposure to environmental toxins1. Since then the credibility of this suggestion has grown, with around 50 research papers published up to 2010, and some 700 now2.

While controlled trials of human exposure to potentially hazardous chemicals are unethical, the evidence available meets most of the Bradford-Hill criteria for causality: meta-analyses show consistent associations, temporal sequencing, dose-response gradients, plausible mechanisms, and coherence with laboratory animal evidence.

While there are concerns that the effect sizes for environmental endocrine disruptors may be small, a preliminary comparison with effect sizes for sugary drink consumption, TV watching, maternal adiposity or gestational diabetes, suggests that endocrine disruptors may rank at a similar level3. The analysis is hampered by the large number of potential chemical disruptors in the modern environment and their various effects on appetite control, lipid storage and adipogenesis.

Chemical pollutants

The most commonly cited chemicals are found in food packaging, including plastic bottles, plastic wrapping and the interior lining of beverage cans – making a distinction between unhealthy diets and unhealthy exposure to food packaging pollutants hard to differentiate. The chemicals are also found in other products including cosmetics, soft furnishings, road dust (from tyres) and agricultural sprays.

Avoiding these chemicals is clearly a major problem: they are invisible and generally tasteless in the amounts that are physiologically active. But if they are indeed a significant component of the risk of obesity then we may have an explanation of why even the most carefully controlled study on improving diet and physical activity, in schools and communities, show only small improvements in BMI status4.

For policy-makers, the key questions are whether the risks are significant and what interventions would reduce that risk. The degree of risk remains to be shown, while the policy options are limited: relying on individuals not to consume invisible and pervasive chemicals is unrealistic, medical interventions to tackle endocrine disruptors are not widely available, leaving only population-level restriction on the production and use of these persistent pollutants – not an easy task when the products are embedded in many industrial systems, and while the proof of their harm remains challengeable.

Also important, and especially relevant when the World Obesity Federation is calling for a ‘reframing of the narrative’ to tackle stigma, is the potential to blame individuals for their weight gain and obesity when there is nothing they can do to prevent this. World production of endocrine disrupting chemicals has risen dramatically in the last 50 years and the chemicals are now widely distributed in human populations5Asking us to avoid them is futile.

By Dr Tim Lobstein.

  1. P.F. Baillie-Hamilton (2002). Chemical toxins: a hypothesis to explain the global obesity epidemic. J. Altern. Complement. Med. 8:185–192.
  2. National Library of Medicine: PubMed search “obesity + endocrine + disruptors” May 2nd 2024.
  3. Lobstein T & Brownell K (2021). Endocrine-disrupting chemicals and obesity risk: A review of recommendations for obesity prevention policies. Obesity Reviews 
  4. Brown T, et al. (2019). Interventions for preventing obesity in children. Cochrane Library. 
  5. Flaws J, et al. Plastics, EDCs and Health. Washington DC: Endocrine Society. 2020.

Read Tim Lobstein's letter

The World Obesity Federation’s policy advisor Tim Lobstein has raised concerns over the policies needed to reduce the risk of obesity arising from environmental persistent chemicals.

Writing in the journal Lancet Diabetes and Endocrinology he notes that individual have little choice about their exposure to these invisible pollutants and that policy-makers need a better understanding of the health risks attributable to these chemicals.

Read it here