What is Bisphenol A?

Bisphenol A is a chemical compound used to manufacture polycarbonate plastic and epoxy resins.  Polycarbonate plastic and epoxy resins are used as linings on many consumer products and used in the manufacture of flame retardants, so Bisphenol A is one of the most widely used chemicals worldwide.  As a result we may come in contact with Bisphenol A through many common household products and personal items. [1, 2]

We are concerned about the use of Bisphenol A in many household products because animal studies suggest that it may act as an “endocrine disruptor” and biomonitoring by the Centers for Disease Control and Prevention shows that most Americans have detectable levels of Bisphenol A in their urine. [3]  The following sections discuss how your children may be exposed to Bisphenol A,  what health effects are associated with exposure, what can be done to reduce your family’s exposure, and where you should go for additional help

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How may my child be exposed to Bisphenol A?

Your child may be exposed to Bisphenol A in the environment and at home.  Environmental exposures, such as breathing air, drinking water, or handling soil contaminated with Bisphenol A, tend to be limited because contamination is not typically widespread or at levels of concern. Exposures that occur in the home, on the other hand, may occur more frequently. [2]  This is because of the widespread use of polycarbonate plastics in household products, such as the following:

• Food and drink containers
• Plastic bottles
• Baby bottles
• Dental sealants
• Automobile parts

Bisphenol A is typically bound in the polycarbonate plastic of these household products through strong chemical bonds, so we are unlikely to be exposed to Bisphenol A by simply handling plastic products. [1]  However, routine activities like heating liquids, storing acidic foods, and washing containers may create conditions where Bisphenol A may be released from a polycarbonate plastic [1, 2, 4, 5].  As a result, Bisphenol A may leach directly into food, resulting in exposure when the food is consumed. 

The amount of Bisphenol A that may leach into food and consumed is likely to be very small, but may occur frequently over a long period of time.  This is commonly referred to as a chronic exposure.  Chronic exposures do not typically cause immediate adverse health effects.  Chronic exposures may, however, result in gradual molecular changes in the body.  These changes may result in adverse health effects, particularly if exposures occur during a sensitive period of development, such as prenatal development or puberty. 

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What health effects are associated with exposure to Bisphenol A?

Many health professionals are concerned about Bisphenol A exposure because it shares many chemical properties with hormones naturally found in the body.  These natural hormones regulate many physiological functions in the body, including reproduction and normal cell growth, which may be disrupted by Bisphenol A. [6] 

            Reproductive Effects

Animal research has shown that Bisphenol A is able to bind with estrogen receptors found on both the plasma membrane and nucleus of cells in several organ systems including the brain, mammary glands, and reproductive tract.  These estrogen receptors normally interact with the female hormone estrogen, which is involved in the regulation of normal sexual development.  As a result, Bisphenol A may be able to disrupt normal sexual development in girls and boys, resulting in altered sexual differentiation and sexual organ development. This disruption may lead to different reproductive effects in girls and boys.  In particular, animal studies have shown that Bisphenol A exposure may lead to advanced onset of puberty and disruption of normal menstrual cycles in girls and decreased sperm production and quality in boys.  [6]  

Cancer

The interaction between Bisphenol A and estrogen receptors may alter cell growth and increase the rate of normal cell proliferation.  Increased cell proliferation can increase an individual’s susceptibility to developing cancer.  Some cancers that have been shown to be associated with Bisphenol A exposure in animal studies include: 

• Breast Cancer- Bisphenol A exposure may increase sensitivity to estrogen, increasing a woman’s risk of developing breast cancer. [7]
• Uterine Cancer- Bisphenol A may stimulate proliferation of uterine epithelial cells, increasing women’s risk of cancer if they are exposed to other carcinogens. [8, 9]
• Prostate Cancer- Bisphenol A may causes permanent changes in the structure and cell growth regulation of the prostate, increasing men’s risk of developing prostate cancer later in life. [10]

Low-Dose Controversy

The adverse health effects caused by Bisphenol A are controversial and are a widely debated subject. [1, 6, 11]  This is because the health effects associated with low-dose exposures, such as ingestion of food contaminated with Bisphenol A, are difficult to evaluate in human studies.  Therefore, animal studies are typically conducted to better understand what effects may be caused in humans.  Unfortunately, it is also difficult to draw conclusions from animal studies.  This is because the studies typically require exposing test subjects to high doses that may not be relevant and may use animals with physiological systems that are different than humans.

Although there are limitations that make it difficult to definitively demonstrate that low-dose chronic exposures to Bisphenol A causes adverse health effects, there is evidence that exposure causes adverse effects.  Therefore, it is recommended to minimize exposures whenever practical 

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How can I reduce my family’s exposure to Bisphenol A?

The Institute for Agriculture and Trade Policy’s Food and Health program has developed a fact sheet entitled “Smart Plastics Guide Healthier Food Uses of Plastics.” The fact sheet provides information on the health and safety of containers and recommendation to minimize exposure to chemicals in plastic. [12] 

The fact sheet includes a useful guide on the plastic labels found on some plastic household products.  There are currently 7 labels used on plastic products, which can be used to determine what chemicals are used in plastic products in your home. Plastic containers with #1, #2, #4, or #5 labels are less likely to contain Bisphenol A and are generally considered safer containers for storing food and liquids.  Plastic containers with #3, #6, and #7 labels are more likely to contain Bisphenol A and other chemicals that may have similar health effects. 

You can reduce your family’s exposure to Bisphenol A by minimizing the use of #3, #6, and #7 plastic containers to store and heat food.  In addition, some practical tips you can do to reduce your family’s exposure when labeling information is not readily available include:

• Use non-plastic containers to heat and store food
• Replace older plastic containers that show sign of wear
• Avoid the use of harsh detergents, which may increase Bisphenol A leaching, when washing plastic containers

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What should I do if I am concerned my child is being exposed to unsafe levels of Bisphenol A?

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References

[1] vom Saal, F.S., and Hughes, C. An Extensive New Literature Concerning Low-Dose Effects of Bisphenol A Shows the Need for a New Risk Assessment. Environ Health Perspectives. 2005, 113(8): 926–933.

[2] Kang, J.H., Kito, K., and Kondo, F. Factors influencing the migration of bisphenol A from cans. Journal of Food Protection. 2003, 66(8): 1444-7.

[3] Calafat, A.M., Kuklenyik, Z., Reidy J.A., Caudill S.P., Ekong J., Needham L.L. Urinary Concentrations of Bisphenol A and 4-Nonylphenol in a Human Reference Population. Environmental Health Perspectives. 2005, 113(4): 391-395.

[4] Brotons J.A., Olea-Serrano M.F., Villalobos M., Pedraza V., Olea N. Xenoestrogens released from lacquer coatings in food cans. Environmental Health Perspectives. 1995, 103(6): 608-12.

[5] See Reference 2.

[6] Maffini, M.V., Rubin, B.S., Sonnenschein, C., and Soto, A.M., Endocrine disruptors and reproductive health: The case of bisphenol-A. Molecular and Cellular Endocrinology. 2006, 254-255: 179-186.

[7] Munoz de Toro, M, Markey, C.M., Wadia, P.R., Luque, E.H., Rubin, B.S., Sonnenschein, C., and Soto, A.M. Perinatal exposure to Bisphenol A alters peripubertal mammary gland development in mice. Endocrinology. 2005, 146: 4138-4147.

[8] Markey, C.M., Wadia, P.R., Rubin, B.S., Sonnenschein, C., and Soto, A.M., Long-term effects of fetal exposure to low doses of the xenoestrogen bisphenol-A in the female mouse genital tract. Biological Reproduction. 2005. 72: 1344-1351.

[9] Couse, J.F., Davis, V.L., Hanson, R.B., Jefferson, W.N., McLachlan, J.A., Bullock, B.C., Newbold, R.R., and Korach, K.S., Accelerated onset of uterine tumors in transgenic mice with aberrant expression of the estrogen receptor after neonatal exposure to diethylstilbestrol. Molecular Carcinogenesis. 1997, 19: 236-242.

[10] Timms, B.G., Howdshell, K.L., Barton, L., Bradley, S., Richter, C.A., and von Saal.  Estrogenic chemicals in plastic and oral contraceptives disrupt development of the fetal mouse prostate and urethra. Proceedings from the National Academy of Science. 2005, 102: 7014-7019.

[11] See Reference 6.

[12] Smart Plastics Guide Healthier Food Uses of Plastics.  2005  [cited 2007 September, 25]; Available from: http://www.agobservatory.org/library.cfm?refid=77083.

[13] Public Health Statement: Phenol (CAS# 108-95-2). Agency for Toxic Substances and Disease Registry, 2006.

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