15 December, 2016: 

There is increasing interest in chemicals called 'endocrine-disrupting chemicals'. These are chemicals, which may be natural or synthetic, that through exposure interfere with an organism's normal hormone balance. The actions of these chemicals are complex. Some have weak endocrine-like actions and others interfere with the pathways through which our hormones normally work, hence the term 'disrupters'. Endocrine disrupter chemicals include chemicals such as DDT and other pesticides, and plasticizers, such as bisphenol A (BPA) as well as phthalates and parabens.

The Endocrine Society guideline on this issue in 2009 [1] stated that 'The evidence for adverse reproductive outcomes (infertility, cancers, malformations) from exposure to endocrine-disrupting chemicals is strong, and there is mounting evidence for effects on other endocrine systems, including thyroid, neuroendocrine, obesity and metabolism, and insulin and glucose homeostasis.' The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals, 2015 [2] recognizes this to be an international problem and that more public awareness as to how to minimize personal exposure, plus more research in this area, is needed. Of considerable concern is that endocrine disrupters can cause epigenetic changes, such as DNA methylation which can be transmitted to offspring [2].

Both BPA and phthalates have been associated with obesity in cross-sectional studies [2]. Causation is yet to be firmly established. However, the Endocrine Society's position on this issue is that agents such as BPA are obesogenic and contribute to insulin resistance and alterations in energy expenditure. We are mainly exposed to BPA through food contamination including the inner coating of food cans and polycarbonate storage containers, tableware and water bottles. Therefore, there is increasing interest in the effects of reducing BPA exposure. This includes not only reducing exposure through foods, but also through cosmetics and personal hygiene products packaged in plastics. The latter are particularly applicable to women.

Can we reduce our exposure to these environmental chemicals? A recent pilot study looked at reducing BPA exposure in women [3]. In the study of 24 women, half were randomly allocated to 3 weeks of reduced BPA exposure and half to no intervention. The reduced exposure group had a weekly face-to-face meeting and were given BPA-free cosmetics, personal hygiene products, glass food/water containers, and daily self-monitored major sources of BPA. The intervention group had a significant reduction in the amount of BPA in their urine over the 3 weeks. This study provides evidence that BPA exposure can be reduced and provides a model for further studying the effects of BPA reduction in humans, such as on obesity.

Meanwhile, there are ways to reduce BPA exposure. These include using glass storage containers and reducing the consumption of canned food and drinks in plastic bottles that are not BPA-free.

Other endocrine disrupters of interest include phthalates and parabens. Parabens are used as preservatives, notably in personal care products and some of these have extremely weak estrogenic activity. Phthalates are almost ubiquitous in personal care products such as perfume, cosmetics, moisturizer, nail polish, liquid soaps, and hair spray and have been implicated as endocrine disrupters. Researchers are investigating the role of these chemicals in conditions ranging from obesity and cancer through to premature ovarian failure and polycystic ovarian syndrome. In rodents, exposure to BPA and phthalates during gestation resulted in a range of endocrinopathies (including premature ovarian failure and polycystic ovarian syndrome) in subsequent generations [4]. While this research is ongoing, exposure to parabens and phthalates can be achieved by using paraben- and phthalate-free personal care products.

Susan Davis
Director, Women's Health Research Program, School of Public Health and Preventive Medicine, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia

References

1. Diamanti-Kandarakis E, Bourguignon JP, Giudice LC, et al. Endocrine-disrupting chemicals: an Endocrine Society scientific statement. Endocr Rev 2009;30:293-342
   http://www.ncbi.nlm.nih.gov/pubmed/19502515 
2. Gore AC, Chappell VA, Fenton SE, et al. EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals. Endocr Rev 2015;36:E1-150
   http://www.ncbi.nlm.nih.gov/pubmed/26544531 
3. 3. Hagobian T, Smouse A, Streeter M, Wurst C, Schaffner A, Phelan S. Randomized intervention trial to decrease bisphenol A urine concentrations in women: pilot study. J Womens Health (Larchmt) 2016 Oct 11. Epub ahead of print
   http://www.ncbi.nlm.nih.gov/pubmed/27726525 
4. 4. Manikkam M, Tracey R, Guerrero-Bosagna C, Skinner MK. Plastics derived endocrine disruptors (BPA, DEHP and DBP) induce epigenetic transgenerational inheritance of obesity, reproductive disease and sperm epimutations. PLoS One 2013;8:e55387
   http://www.ncbi.nlm.nih.gov/pubmed/23359474