1) We’ve heard a lot in the media recently about endocrine disrupters, or endocrine disrupting chemicals (EDCs). What exactly are they?
EDCs are mostly synthetic chemicals that, when absorbed into the body, may interfere with the body’s endocrine system. The endocrine system is the exquisitely balanced system of glands and hormones that regulates our bodies' vital functions such as growth, response to stress, sexual development and behaviour, production and utilization of hormones, rate of metabolism, intelligence and behaviour. EDCs can affect the body’s development, growth and hormone balance by mimicking, blocking or disrupting the body’s natural hormones.
2) Where are EDCs found?
EDCs are found in cosmetics, cleaning compounds, baby and children’s toys, food storage containers, furniture and carpets, computers, phones, and appliances. We encounter them as plastics and resins every day in our cars, trucks, planes, trains, sporting goods, outdoor equipment, medical equipment, dental sealants, and pharmaceuticals. Many of the personal care products (creams, shampoos and cosmetics) are fragranced, and these fragrances contain the EDC- phthalates, a plasticizer. Not only are phthalates found in our perfume, moisturizers, nail polish and hair spray, but they are in paints, floor tiles and sex toys.
3) Why are EDCs potentially so bad for us: men, women and babies?
Human health depends on a well-functioning endocrine system to regulate the release of certain hormones that are essential for functions such as metabolism, growth and development, sleep and mood. Chemicals used in everyday products and industrial processes can affect the body’s development, growth and hormone balance by mimicking, blocking or disrupting the body’s natural hormones. Researchers have linked EDCs to breast and prostate cancer, changes in immune system function, obesity, early menopause, as well as the development of non-descended testes in young males and early puberty in girls.
One very clear example of how EDCs are linked to negative health effects in humans is the case of DES daughters. Between 1950-1960, pregnant women were prescribed diethylstilbestrol (DES), a synthetic estrogen, to prevent miscarriages. It not only failed to prevent them, but in 1971, doctors began reporting high rates of unusual vaginal cancers in teenage girls. Investigations traced the links back to their mothers that took DES. Other health issues these women suffered were birth defects, and immune system suppression.
4) How are EDCs potentially linked to the risk of breast cancer?
Endocrine-disrupting chemicals influence our risk of breast cancer indirectly by changing the body's natural hormonal balance. Certain cancers, including breast cancer, are sensitive to hormonal changes.
Two decades of research suggest that phthalates, one of the most common EDCs, disrupt hormonal systems and may be linked to breast cancer. (1). Phthalates have also been shown to cause proliferation of breast tumor cells, rendering anti-estrogen treatments, such as tamoxifen, less effective against tumors. (2)
Parabens are estrogen mimickers (3), disrupting the delicate endocrine balance in our bodies. Concentrations of parabens were identified in biopsy samples from breast tumors in 2004. (4) A similar study (5) was repeated in 2012 in England where again, concentrations of parabens were measured at locations across the human breast using human breast tissue collected from 40 mastectomies in England. Triclosan is also suspected of disrupting the hormonal system. (6)
5) There is a lot of attention paid to EDCs in North America and Europe. What is Canadian policy on regulating, or restricting the use of EDCs? How does our policy differ from policy, say, in Europe?
Within the EU several legislative initiatives have been taken to limit the use of high concern chemicals. Since 2007 the broad and horizontal REACH regulation gives a framework for regulating and restricting the use of the most hazardous substances. The use of chemicals is also regulated in sector specific product directives which restricts the use of hazardous chemicals in for example toys, cosmetics and electronic products.
REACH aims to place the burden of proof on industry, which has to collect or generate the data necessary to ensure the safe use of chemicals. There is also an on-going EU discussion about criteria for endocrine disrupting chemicals. Within the scope of the pesticide regulation, the European Commission will present criteria for the determination of endocrine disrupting properties by the end of 2013.
Canada, in 2008, became the first country to ban plastic baby bottles with bisphenol A after concluding the chemical was toxic. While this action is applauded, the possibility that a particular chemical might mimic a hormone like estrogen is not accounted for in any regulation standard. The most notable effect that is being tested for is whether a substance causes cancer and at what levels of exposure. That usually sets the standard although there might be other adverse health endpoints such as respiratory damage. Current standards ignore whether a substance is a hormonal mimicker or not.
Within Canada, under The Canadian Environmental Protection Act (CEPA), the Chemical Management Plan does not include a gender analysis nor does it refer to EDCs as a separate category of chemicals. Neither does the labelling of consumer products under the Canada Consumer Product Safety Act (CCPSA), previously the Hazardous Protection Act, of Health Canada include EDCs as a distinct category, nor does it include a gender analysis. And unfortunately in Canada we have not yet placed the burden of proof on companies to show their chemicals are safe.
1. Jobling S, Reynolds T, White R, Parker MG, Sumpter JP (1995). A variety of environmentally persistent chemicals, including some phthalate plasticizers, are weakly estrogenic. Environmental Health Perspectives 103(6):582-7.
2. Kim IY, Han SY, Moon A (2004). Phthalates inhibit tamoxifen-induced apoptosis in MCF-7 human breast cancer cells. Journal of Toxicology and Environmental Health 67: 2025-2035.
3. Darbre, P. D., & Harvey, P. W. (2008). Paraben esters: review of recent studies of endocrine toxicity, absorption, esterase, and discussion of possible health risks. J Appl Toxicol, 28, 561–578.
4. Darbre, P., Aljarrah, A., & Miller, W. (2004). Concentrations of parabens in human breast tumours. J Appl Toxicol, 24, 5–13.
5. L. Barr, G. Metaxas, C. A. J. Harbach, L. A. Savoy and P. D. Darbre (2012) Measurement of paraben concentrations in human breast tissue at serial locations across the breast from axilla to sternum (pages 219–232)
6. Gee, RH et al. (Jan 2008): "Oestrogenic and androgenic activity of triclosan in breast cancer cells." Appl Toxicol.28, 1,78-91.