05 Feb Endocrinology Journal Editor Discusses Effects of Environmental Endocrine-Disrupting Chemicals
MedicalResearch.com Editor’s Note: Dr. Gore, Editor-in-Chief of the Journal Endocrinology, has graciously answered several questions regarding the recent concerns of environmental chemicals linked to both early puberty and early menopause.
Medical Research: How can chemicals found inside the home impact onset of menopause?
Dr. Gore: It is important to clarify that the cause-and-effect relationship between chemicals and menopause is not established. The timing of menopause in women is due to a variety of factors including genetic traits, nutritional status, and general health or chronic disease. Some research on humans, including the recent study by Grindler et al., also suggests that environmental chemicals may contribute to the timing of earlier menopause. Animal models also suggest an advance in the timing of reproductive failure following earlier life exposures to endocrine-disrupting chemicals (EDCs). [See references below]. The question of exactly how chemicals may change the timing of menopause is therefore unresolved, but based on animal studies it is likely that the mechanisms include effects of endocrine-disrupting chemicals on the expression of genes and proteins involved in ovarian function that may lead to premature loss of follicles (eggs). Because the control of reproduction involves the brain and the pituitary gland, as well as the ovary, it is possible that endocrine-disrupting chemicals also impair how these organs regulate reproductive hormones.
- Gore AC, Walker DM, Zama AM, Armenti AE, Uzumcu M. Early
life exposure to endocrine-disrupting chemicals causes lifelong molecular
reprogramming of the hypothalamus and premature reproductive
aging. Mol Endocrinol. 2011;25:2157–2168.
- Shi Z, Valdez KE, Ting AY, Franczak A,GumSL, Petroff BK. Ovarian
endocrine disruption underlies premature reproductive senescence
following environmentally relevant chronic exposure to the
aryl hydrocarbon receptor agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin.
Biol Reprod. 2007;76:198–202.
- Akkina J, Reif J, Keefe T, Bachand A. Age at natural menopause and
exposure to organochlorine pesticides in Hispanic women. J Toxicol
Environ Health A. 2004;67:1407–1422.
- Cooper GS, Savitz DA, Millikan R, Chiu Kit T. Organochlorine
exposure and age at natural menopause. Epidemiology. 2002;13:
- Hatch EE, Troisi R, Wise LA, et al. Age at natural menopause in
women exposed to diethylstilbestrol in utero. Am J Epidemiol.
- KnoxSS, Jackson T, Javins B, Frisbee SJ, Shankar A, DucatmanAM.
Implications of early menopause in women exposed to perfluorocarbons.
J Clin Endocrinol Metab. 2011;96:1747–1753.
- Farr SL, Cai J, Savitz DA, Sandler DP, Hoppin JA, Cooper GS.
Pesticide exposure and timing of menopause: the Agricultural
Health Study. Am J Epidemiol. 2006;163:731–742.
Medical Research: What are the primary sources of exposure to these chemicals?
Dr. Gore: Endocrine-disrupting chemicals exposures come from a variety of sources, including plastic containers (e.g. water bottles) and other products, certain foods, personal care products, pesticides, and many others.
Medical Research: Are these potentially harmful chemicals properly screened and regulated?
Dr. Gore: For the most part, the regulatory process is not adequate to identify all chemicals with endocrine-disrupting activity. Much of this process involves standard toxicity testing using relatively high doses and extrapolating downwards to establish a “safe” dose. However, the endocrine system’s hormones can have biological actions in the body at extremely low dosages, and endocrinologists believe that this is also true for EDCs. Therefore, many endocrine-disrupting chemicals may be missed by regulators who do not conduct low-dose testing.
[Reference: Vandenberg LN, Colborn T, Hayes TB, Heindel JJ, Jacobs DR Jr, Lee DH, Shioda T, Soto AM, vom Saal FS, Welshons WV, Zoeller RT, Myers JP. Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses. Endocr Rev. 2012 Jun;33(3):378-455. doi: 10.1210/er.2011-1050.
Medical Research: Why does there seem to be a lack of agreement on the potential harm of these chemicals?
Dr. Gore: It is extremely important to apply basic endocrine principles in identifying a potential endocrine-disrupting chemical. This includes the understanding of low-dose effects, as well as an appreciation that effects of a hormone (or EDC) at one dose may not predict the response at another dose. Furthermore, it is becoming increasingly clear that the timing of exposure may actually be more important than the dose. Recent endocrine research shows that early developmental stages, such as in the fetus and infant, are particularly vulnerable to perturbations of hormones. Exposures at these times can change the developing body and brain, and result in a disease or dysfunction later in life. Associations between early life exposures to endocrine-disrupting chemicals and obesity/diabetes, reproductive impairments, thyroid disease, and hormone-sensitive cancers, have been clearly demonstrated in animal models. However, extrapolating these results to humans is difficult due to the long lag between early life periods and the timing when a disease may be manifested, often decades later. Epidemiological studies such as this one add to our understanding of endocrine-disrupting chemicals and human disease.
[Reference: Zoeller RT, Brown TR, Doan LL, Gore AC, Skakkebaek NE, Soto AM, Woodruff TJ, Vom Saal FS. Endocrine-disrupting chemicals and public health protection: a statement of principles from The Endocrine Society. Endocrinology. 2012 Sep;153(9):4097-110.]
Medical Research: What can we do to limit our exposure to these chemicals?
Dr. Gore: Some chemicals can be avoided by eliminating them from our homes and our refrigerators. If possible, replace processed foods (which can add chemicals to food, and put the food into contact with storage containers made of chemicals) with fresh food. Wash fruit and vegetables to remove residues of pesticides. In your home and yard, avoid chemical pesticides if possible. Keeping a house clean, plugging holes in the kitchen to keep out insects and rodents, and removing sources of food for pests (e.g. garbage) will reduce the need to use pesticides.
MedicalResearch.com Interview with: Dr. Andrea Gore PhD, Gustavus & Louise Pfeiffer Professor, & University of Texas Austin/Div of Pharmacology/Toxicology (2015). Endocrinology Journal Editor Discusses Effects of Environmental Endocrine-Disrupting Chemicals MedicalResearch.com