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Questions and Answers about the Draft National Toxicology Program Brief on Bisphenol A
The National Toxicology Program (NTP) Draft Brief On Bisphenol A (BPA) (http://cerhr.niehs.nih.gov/chemicals/bisphenol/bisphenol.html)
Next Steps – Public Comments, Peer Review, Developing The NTP Monograph
The Center for the Evaluation of Risks to Human Reproduction (CERHR)
The CERHR Expert PanelBisphenol A
The National Toxicology Program (NTP) Draft Brief On Bisphenol A (BPA)What is an NTP Brief?The National Toxicology Program Draft Brief on Bisphenol A (BPA) includes the NTP’s conclusions on the reproductive and developmental hazards associated with exposure to bisphenol A. The NTP Draft Brief is based on the report completed in Fall 2007 by an expert panel on bisphenol A convened by the NTP Center for the Evaluation of Risks to Human Reproduction (CERHR), public comments received on the report, and new relevant scientific literature. The Draft NTP Brief on Bisphenol A is not a quantitative risk assessment, nor is it intended to supersede risk assessments conducted by regulatory agencies. The Draft NTP Brief on Bisphenol A is intended to serve as an environmental health resource for the public, as well as regulatory and health agencies. The scientific literature on bisphenol A is complex and rapidly expanding. The goal of the NTP Brief on Bisphenol A is to present a balanced evaluation of this literature and identify potential health concerns related to reproduction and development, as well as to present areas of scientific uncertainty. This information may be useful to regulatory agencies as they initiate or revise their risk assessments. What are the main draft conclusions in The National Toxicology Program (NTP) Draft Brief On Bisphenol A (BPA)?The National Toxicology Program (NTP) concurs with the conclusion of the Center for the Evaluation of Risks to Human Reproduction (CERHR) Expert Panel on Bisphenol A that there is some concern for neural and behavioral effects in fetuses, infants, and children at current human exposures. The NTP also has some concern for bisphenol A exposure in these populations based on effects in the prostate gland, mammary gland, and an earlier age for puberty in females. The scientific evidence that supports a conclusion of some concern for exposures in fetuses, infants, and children comes from a number of laboratory animal studies reporting that "low" level exposure to bisphenol A during development can cause changes in behavior and the brain, prostate gland, mammary gland, and the age at which females attain puberty. These studies only provide limited evidence for adverse effects on development and more research is needed to better understand their implications for human health. However, because these effects in animals occur at bisphenol A exposure levels similar to those experienced by humans, the possibility that bisphenol A may alter human development cannot be dismissed. The NTP has negligible concern that exposure of pregnant women to bisphenol A will result in fetal or neonatal mortality, birth defects, or reduced birth weight and growth in their offspring. In laboratory animals, exposure to very high levels of bisphenol A during pregnancy can cause fetal death and reduced birth weight and growth during infancy. These studies provide clear evidence for adverse effects on development, but occur at exposure levels far in excess of those experienced by humans. Two recent human studies have not associated bisphenol A exposure in pregnant women with decreased birth weight or several other measures of birth outcome. Results from several animal studies provide evidence that bisphenol A does not cause birth defects such as cleft palette, skeletal malformations, or grossly abnormal organs. The NTP concurs with the conclusion of the CERHR Expert Panel on Bisphenol A that there is negligible concern that exposure to bisphenol A causes reproductive effects in non-occupationally exposed adults and minimal concern for workers exposed to higher levels in occupational settings. Data from studies in humans are not sufficient to determine if bisphenol A adversely affects reproduction when exposure occurs during adulthood. A number of studies, when considered together, suggest a possible effect on reproductive hormones, especially in men exposed to higher levels of bisphenol A in the workplace. Laboratory studies in adult animals show adverse effects on fertility, estrous cycling, and the testes at exposure levels far in excess of those experienced by humans. A number of other effects, such as decreased sperm counts, are reported for the reproductive system at lower doses in animals exposed only during adulthood, but these effects have not been shown to be reproducible. Laboratory animal studies consistently report that bisphenol A does not affect fertility.
Can you explain the levels of concern used by the NTP and the Expert Panel in their conclusions?The five levels of concern used by NTP and the CERHR expert panels are, from highest to lowest:
The NTP or panel may express "serious concern" if a substance is found to cause reproductive or developmental effects in humans or if human exposures are similar to doses that clearly cause adverse developmental or reproductive effects in laboratory animals. At the opposite extreme, a conclusion of "negligible concern" may be warranted when the available data provide good evidence that the substance under evaluation is not a reproductive or developmental toxicant or human exposures are very low compared to dose levels that cause adverse effects in laboratory animals. The NTP and expert panel conclusions are based on the weight of scientific evidence and integrate toxicity and exposure information. Conclusions are presented in narrative form and present the best scientific judgment on the likelihood that adverse reproductive and/or developmental effects may occur under the exposure circumstances specified, i.e., a qualitative statement of potential risk. The likelihood of an adverse effect resulting from human exposure is expressed as a level of concern. How does the NTP Draft Brief on Bisphenol A differ from the Bisphenol A Expert Panel Report?The Draft NTP Brief is a government document that presents the NTP’s draft conclusions on the possible effects of bisphenol A on human development and reproduction. The Expert Panel Report on bisphenol A is an advisory document prepared by an independent panel of scientists and submitted to the NTP. For bisphenol A, the draft conclusions of the NTP are in general agreement with those of the expert panel. However, the NTP conclusions reflect a higher level of concern than those expressed by the expert panel for possible effects of bisphenol A on prostate gland, mammary gland, and early onset of puberty in exposed fetuses, infants, and children. The NTP draft conclusions are based on a thorough evaluation of the expert panel report and the scientific papers cited in that report, information received in public comments on the expert panel report, and consideration of numerous scientific publications that became available after the cut-off date for literature considered by the expert panel. What information did the NTP consider in preparing the Draft Brief?All new articles related to the potential reproductive and developmental effects of bisphenol A were considered during preparation of the draft NTP Brief on Bisphenol A. However, only those publications that were considered the most informative for developing NTP conclusions are cited in the Draft NTP Brief. What is the bottom line? Can Bisphenol A affect human development or reproduction?Possibly. Although there is no direct evidence that exposure of people to bisphenol A adversely affects reproduction or development, studies with laboratory rodents show that exposure to high dose levels of bisphenol A during pregnancy and/or lactation can reduce survival, birth weight, and growth of offspring early in life, and delay the onset of puberty in males and females. Recognizing the lack of data on the effects of bisphenol A in humans and despite the limitations in the evidence for "low" dose effects in laboratory animals, the possibility that bisphenol A may impact human development cannot be dismissed. More research is needed. See the The National Toxicology Program (NTP) Draft Brief On Bisphenol A (BPA) (http://cerhr.niehs.nih.gov/chemicals/bisphenol/bisphenol.html) for a more detailed response. Next Steps – Public Comments, Peer Review, Developing The Ntp MonographHow do I provide comments on the NTP Draft Brief on Bisphenol A?The NTP invites written public comments on the draft NTP Brief on Bisphenol A and/or presentation of oral comments at the NTP Board of Scientific Counselors meeting. For more information visit the NTP Board of Scientific Counselors meetings (http://ntp.niehs.nih.gov/go/165) Web site. Public comments should be submitted to: Dr. Barbara Shane
Executive Secretary for the NTP Board of Scientific Counselors NTP Office of Liaison, Policy and Review,
NIEHS, P.O. Box 12233, MD A3-01 Research Triangle Park, NC 27709 Tel (919) 541-4253 Fax (919) 541-0295 shane@niehs.nih.gov Courier address: NIEHS 111 T.W. Alexander Drive, Room A322 Research Triangle Park, NC 27709 When does the public comment period close?The public comment period closes on May 23, 2008. Will the public comments be made available?All public comments will be posted on the NTP CERHR Web site (http://cerhr.niehs.nih.gov/chemicals/bisphenol/bisphenol.html). Is the NTP Draft Brief on Bisphenol A Peer-Reviewed?The draft NTP Brief on Bisphenol A will undergo scientific peer review at the NTP Board of Scientific Counselors meeting scheduled for June 11-12, 2008, at the Radisson Hotel, Research Triangle Park, 150 Park Drive, Research Triangle Park, NC 27709. What is an NTP-CERHR Monograph?The NTP-CERHR Monograph is a collection of information on a particular chemical that includes the NTP Brief, the Expert Panel Report, and the public comments on the Panel Report. NTP-CERHR Monographs are made publicly available and transmitted to appropriate health and regulatory agencies. When will the NTP-CERHR Monograph on BPA be available?The NTP-CERHR Monograph will likely be available in late summer 2008. What happens once the NTP-CERHR Monograph becomes available?We share the results widely. The NTP-CERHR Monograph will be added to the NTP/CERHR and the NIEHS web site, and distributed to federal and state agencies and interested individuals and organizations. It is also indexed in PubMed. The NTP will share the Monograph broadly to ensure that the public, as well as government health, regulatory, and research agencies have the information to use when acting on public health issues. The NTP has no regulatory authority. The Center for the Evaluation of Risks to Human Reproduction (CERHR)What is the National Toxicology Program?The National Toxicology Program (NTP) is an interagency program established in 1978 by the Secretary of Health, Education and Welfare, which today is known as the U.S. Department of Health and Human Services. The program was created as a cooperative effort to coordinate toxicology testing programs within the federal government, strengthen the science base in toxicology, develop and validate improved testing methods, and provide information about potentially toxic chemicals to health, regulatory, and research agencies, scientific and medical communities, and the public. The NTP is headquartered at the NIEHS. For more information about the NTP, visit the NTP Web site (http://ntp.niehs.nih.gov). When and why was the NTP CERHR established?The National Toxicology Program (NTP) and the National Institute of Environmental Health Sciences (NIEHS) established the NTP Center for the Evaluation of Risks to Human Reproduction (CERHR) in 1998. CERHR is an environmental health resource for the public, as well as regulatory and health agencies. CERHR provides accessible, scientifically-based, uniform assessments of the potential adverse effects on human reproduction and development resulting from chemical and other exposures. Why did the NTP decide to look at Bisphenol A?CERHR selected bisphenol A for evaluation because it has received considerable attention in recent years due to widespread human exposures and concern for reproductive and developmental effects reported in laboratory animal studies. The CERHR Expert PanelWhat did the NTP CERHR Panel Conclude?CERHR convened a 12-member, independent panel of government and non-government scientists to evaluate the scientific studies on the potential reproductive and developmental hazards of BPA. The expert panel met publicly on March 5 - 7, 2007 and August 6 - 8, 2007. Expert Panel Conclusions For pregnant women and fetuses:
For infants and children:
For adults:
The conclusions noted above are those of the Bisphenol A Expert Panel and should not be construed to represent the views of the NTP. The expert panel reviewed and evaluated the available scientific data on bisphenol A in three primary areas: human exposure, reproductive toxicity, and developmental toxicity. In their deliberations, the expert panel considered the quality, quantity, and strength of the scientific evidence that exposure to bisphenol A might cause adverse effects on human reproduction and/or development of the fetus or infant. The expert panel identified gaps in the available scientific data on the possible effects of bisphenol A and suggested areas where additional research is needed. You can download and read the full report: NTP-CERHR Expert Panel Report on the Reproductive and Developmental Toxicity of Bisphenol A (http://cerhr.niehs.nih.gov/chemicals/bisphenol/BPAFinalEPVF112607.pdf) Who served on the CERHR BPA Expert Panel? List of panel members (http://cerhr.niehs.nih.gov/chemicals/bisphenol/2ndBPAExpertPanel.pdf) Bisphenol AWhat is bisphenol A?Bisphenol A (BPA) is a chemical produced in large quantities for use primarily in the production of polycarbonate plastics and epoxy resins. Where is bisphenol A found?Polycarbonate plastics have many applications including use in certain food and drink packaging, e.g., water and infant bottles, compact discs, impact-resistant safety equipment, and medical devices. Epoxy resins are used as lacquers to coat metal products such as food cans, bottle tops, and water supply pipes. Some polymers used in dental sealants or composites contain bisphenol A-derived materials. In 2004, the estimated production of bisphenol A in the United States was approximately 2.3 billion pounds, most of which was used in polycarbonate plastics and resins. How does bisphenol A get in the body?The primary source of exposure to bisphenol A for most people is through the diet. While air, dust, and water (including skin contact during bathing and swimming) are other possible sources of exposure, bisphenol A in food and beverages accounts for most daily human exposure. Bisphenol A can migrate into food from food and beverage containers with internal epoxy resin coatings and from consumer products such as polycarbonate tableware, food containers, water bottles, and baby bottles. The degree to which bisphenol A leaches from polycarbonate bottles into liquid may depend more on the temperature of the liquid or bottle, than the age of the container. Bisphenol A can also be found in breast milk. Has anyone measured the amount of bisphenol A in humans? If so, who and what are they finding?Biomonitoring studies show that human exposure to bisphenol A is widespread. The 2003-2004 National Health and Nutrition Examination Survey (NHANES III) conducted by the Centers for Disease Control and Prevention (CDC) found detectable levels of bisphenol A in 93% of 2517 urine samples from people six years and older. The CDC NHANES data are considered representative of exposures in the United States. What can I do to prevent exposure to bisphenol A?If you are concerned, you can make personal choices to reduce exposure:
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