Prostate cancer and Bisphenol A.
Bisphenol-A (Health aspects)
Bisphenol-A (Physiological aspects)
Prostate cancer (Risk factors)
|Publication:||Name: Townsend Letter Publisher: The Townsend Letter Group Audience: General; Professional Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2012 The Townsend Letter Group ISSN: 1940-5464|
|Issue:||Date: July, 2012 Source Volume: 348|
|Product:||Product Code: 2866322 Bisphenol-A NAICS Code: 325192 Cyclic Crude and Intermediate Manufacturing SIC Code: 2869 Industrial organic chemicals, not elsewhere classified|
|Geographic:||Geographic Scope: United States Geographic Code: 1USA United States|
Bisphenol A (BPA) is a chemical used in the manufacture of polycarbonate plastic, a type of plastic used for baby bottles and water bottles. It is used in the plastic lining of metal food cans, dental sealants, and the carbonless paper receipts that most cashiers hand out after a purchase. (1) It is estimated that as many as 90% of people in the US have detectable levels of BPA in their bloodstream. (2) BPA has hormone-disrupting effects in the body with links to prostate cancer and other health conditions.
The push to get BPA removed from canned foods had a recent setback March 30 when the Food and Drug Association (FDA) rejected the 2008 Natural Resources Defense Council petition that BPA be declared unsafe and banned from food packaging. The FDA said that it "has determined, as a matter of science and regulatory policy, that the best course of action at this time is to continue our review and study of emerging data on BPA," and that "this announcement is not a final safety determination and the FDA continues to support research examining the safety of BPA." The ruling left the door open for a future ban of BPA in canned foods and other food packaging.
Health Effects of BPA
The FDA ruling states that more evidence of harm needs to be shown, yet the evidence linking BPA to health conditions is there. The Endocrine Disruptor Exchange (TEDX) published a scientific review summarizing studies on the effects of BPA at levels of 1 ppb (1 mg/kg/day) or less. The summary showed that low-dose exposure to BPA is linked to changes in the testes, penis, prostate, and sperm function. BPA can change pancreatic function and is linked with diabetes and cardiovascular disease. The full report on BPA by TEDX can be viewed at www.endocrinedisruption.com/endocrine.TEDXList.overview.php.
One way that BPA affects human health is by altering hormones in the body. BPA has been reported to cause thyroid hormone disruption, alter follicle stimulating hormone, and increase total testosterone. (3) It is also linked to prostate cancer.
Prostate Cancer and BPA
Prostate cancer is the most common solid cancer in males and the second leading cause of cancer deaths in American men. Cancer statistics for 2007 indicate that prostate cancer incidence continues to rise in the US. (4) The reason for this increase is not well understood and is multifactorial. The link to chemicals in the environment is often overlooked. A recent study in animals helps explain the link between hormones, hormone-disrupting chemicals, and prostate cancer.
Studies in rats have shown that estradiol administered during the critical window of prostate development results in marked prostate pathology in adulthood that progress to prostate cancer with aging. (5) Studies have also demonstrated that exposing rats to low doses of BPA increases prostate gland susceptibility to adult-onset prostate cancer, similar to estradiol. (5) BPA is a known estrogen-mimicking compound and has similar effects to estradiol on the prostate gland.
The timing of BPA exposure appears to be important in the development of prostate cancer. It appears that if boys are exposed to BPA during certain times in their lives, it increases their risk for developing prostate cancer as adults. (6) There is a heightened sensitivity of the prostate to BPA during the critical developmental windows that include in utero, neonatal period, and puberty. Thus infants and children may be considered a highly susceptible population for BPA exposure and increased risk of prostate cancers with aging. (6)
Prostate cancers depend on androgens and androgen receptor (AR) activity for growth and progression. BPA alters AR activity through its effects on the estrogen receptor. BPA exposure decreases estrogen receptor-beta (ER-[beta]), a receptor that antagonizes androgen receptor activity and androgen-dependent proliferation of prostatic cells/This reveals one mechanism by which BPA induces prostate tumor cell proliferation.
Because prostate cancer cells depend on androgen, standard treatments of prostate cancer involve targeting androgen receptor function, called androgen deprivation therapy. A subset of prostate cancer cell lines harboring androgen receptor mutations is susceptible to growth stimulation by BPA. A study was done to examine the effect of BPA on the response to standard androgen deprivation treatment. It looked at prostate cancer cells in vivo. BPA stimulated tumor cell proliferation and enhanced tumor growth in cells with an androgen receptor mutation that is common in men. (8) Incidental exposure to BPA may facilitate the transition of a subset of prostate tumors to androgen deprivation therapy resistance. (8) BPA could promote prostate cancer growth in tumors harboring an endogenous androgen receptor mutation, contribute to prostate cancer progression, and alter treatment success.
As evidence mounts showing adverse health effects of BPA, the call to remove this chemical from consumer products grows. Despite the recent FDA setback, environmental groups, concerned citizens, and consumers did succeed in getting one of the largest makers of canned food to remove BPA from the lining. At a February 22, 2012, shareholder meeting, Campbell's Chief Financial Officer Craig Owens reported that the shift to BPA-free cans has begun. Other canned-food companies have already stopped using BPA. A 2010 survey by the report Seeking Safer Packaging found that Hain Celestial, which makes Health Valley, Earth's Best, and Westbrae Natural brands, is BPA free. ConAgra, which makes Chef Boyardee, Hunt's and Healthy Choice brands, and H.J. Heinz Company have removed BPA from their canned foods as well. Muir Glen, a subsidiary of General Mills, announced in 2010 that it would switch to metal cans that do not contain BPA. Eden Foods has been BPA free for years, with a policy in place since 1999. As more companies remove BPA from their canned foods, look for "BPA Free" on the label.
Concerns about BPA have lingered for years. BPA has known hormone-disrupting effects in animals, cell cultures, and humans. Evidence is mounting that connects low-dose BPA with prostate cancer risk. However, more research needs to be done in this area. Avoiding the use of plastic bottles, canned food, and plastic food containers is a good start in reducing exposure to BPA. Getting this chemical and other hormone-mimicking chemicals out of consumer products is the only way to truly eliminate exposure and stop the adverse health effects in humans.
(1.) Vom Saal FS, Myers JP. Bisphenol A and risk of metabolic disorders. JAMA. 2008;300:1353-1355.
(2.) Lang IA et al. Association of urinary bisphenol A concentration with medical disorders and laboratory abnormalities in adults. JAMA. 2008;300:1303-1310.
(3.) Galloway T et al. Daily bisphenol-A excretion and associations with sex hormone concentration: a result from the InCHIANTI adult population study. Environ Health Perspect. 2010:118(11):1603-1608.
(4.) Jemal A, Siegel R, Ward E, et al. Cancer statistics. Ca Cancer I Clio. 2006;56:106-130.
(5.) Prins GS et al. Perinatal exposure to oestradiol and bisphenol A alters the prostate epigenome and increases susceptibility to carcinogenesis. Basic Clin Pharmacol Toxicol. 2008;102(2):134.
(6.) Prins GS. Endocrine disruptors and prostate cancer risk. Endocr Relat Cancer. 2008;15(3):649-656.
(7.) Hess-Wilson JK et al. Unique bisphenol A transcriptome in prostate cancer: novel effects on ERO expression that correspond to androgen receptor mutation status. Environ Health Perspect. 2007;115(11):1646-1653.
(8.) Wetherill YB et al. Bisphenol A facilitates bypass of androgen ablation therapy in prostate cancer. Mot Cancer Ther. 2006;5:3181.
by Marianne Marchese, ND
Dr. Marchese is the author of 8 Weeks to Women's Wellness: The Detoxification Plan for Breast Cancer, Endometriosis, Infertility, and other Women's Health Conditions. Dr. Marchese graduated from the National College of Naturopathic Medicine. She maintains a private practice in Phoenix, Arizona, and teaches gynecology at Southwest College of Naturopathic Medicine. She was named in Phoenix Magazine's 2010 Top Doctor Issue as one of the top naturopathic physicians in Phoenix. Dr. Marchese is a contributing author for the Townsend Letter and lectures on topics related to women's health and environmental medicine throughout the US and Canada.
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