Bisphenol A (BPA)
Bisphenol A (BPA) is an organic compound primarily used in the production of polycarbonate plastics and epoxy resins. Commonly found in food and drink containers, baby bottles, and dental sealants, BPA can leach into substances it contacts, leading to potential human exposure. The compound has drawn attention due to its classification as an endocrine disruptor, which may influence hormone-related health issues, including prostate and breast cancer. Research indicates that even low-level exposure can have adverse effects on development and health, particularly in fetuses and young children. Regulatory bodies, including the FDA and the European Food Safety Authority, have conducted evaluations of BPA's safety, leading to varying conclusions over the years, with some agencies asserting current exposure levels are safe, while others have proposed stricter consumption limits. Ongoing debates and studies continue to assess the implications of BPA exposure, prompting actions such as proposed bans and reassessments of safety standards. The compound's widespread use in consumer products raises important public health discussions, reflecting diverse perspectives on chemical safety and environmental health.
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Bisphenol A (BPA)
ALSO KNOWN AS: 4, 4′-(1-Methylethylidene)bisphenol; 2, 2-bis (4-hydroxyphenyl) propane
RELATED CANCERS: Prostate and breast cancer
DEFINITION: Bisphenol A (BPA) is an organic compound in the aromatic class known as phenols. It is the primary monomer used to manufacture polycarbonate plastics, essentially long chains of individual BPA molecules linked together. All the BPA monomers do not react to form the polymer, which results in small amounts of the unpolymerized free units leaching into the contents of the plastic containers.
Exposure routes: Exposure to BPA is mainly through direct contact or by ingesting food or drink that has been in contact with plastic material containing bisphenol A. BPA is known to leach into the contents of polycarbonate containers under certain conditions. It is also released from epoxy resins that are used in dental sealants, food container linings, polyvinyl chloride (PVC) pipes, and flooring materials. As plastics are used ubiquitously in modern society, bisphenol A has many plausible exposure routes for humans.
Where found: Bisphenol A is a high-production-volume chemical used as the main building block for manufacturing many polymers, such as polycarbonates and epoxy resins. Polycarbonates are widely used for making food and drink containers, baby bottles, milk containers, and water pipes, and epoxy resins are used in the linings of metal food containers and in dental sealants.
At risk: Infants, children, and adults
Etiology and symptoms of associated cancers: The safety data on bisphenol A are controversial. A 2010 report from the Food and Drug Administration (FDA) found it potentially harmful to fetuses, infants, and young children. Still, in 2014, the FDA stated that the current levels of BPA occurring in food were safe based on extensive studies. The European Food Safety Authority (EFSA) also considers the known level of exposure to BPA to be safe as of 2015 but is continuing to investigate some uncertainties. The Environmental Protection Agency (EPA) and the U.K. Food Standards Agency also do not consider BPA a health concern. However, many studies have found adverse effects in animals at relatively low amounts of exposure.
BPA is a known hormone disrupter; many studies have confirmed this effect. Most research data on the adverse effects of BPA exposure have been collected in rodent studies. Low-level chronic exposure to BPA has been reported to cause endocrine disruption even at levels of 2.3 micrograms per kilogram (mcg/kg) per day, leading to aberrant growth of mammary tissue in mice, which is a precursor to breast cancer. Additionally, it has been reported that prenatal exposure to low levels of BPA causes breast cancer in adult rats.
Research reports indicate that BPA at low levels causes adverse effects on the development of the prostate in fetal mice. Studies also suggest that exposure to BPA in the womb alters gene behavior in such a way as to lead to the development of prostate cancer in adult rats.
History: Bisphenol A was first synthesized in 1891. In the 1930s, it was demonstrated that BPA mimicked the action of estrogens in rats. Around that time, diethylstilbestrol, a more potent estrogen, was discovered, relegating BPA to the background regarding pharmacological use. In the 1950s, polymer chemists discovered that BPA could be polymerized readily to make plastics such as polycarbonate. BPA thus became a large-volume chemical used in the plastics industry. It is also used as an inert ingredient in antioxidants, pesticides, and flame retardants. Additionally, it is used in materials for making reinforced pipes, water-main filters, floorings, and enamels. Its ubiquitous use creates various exposure routes for humans.
BPA has been measured in river water, reservoirs, streams, and estuaries. There is ongoing debate about the safety limit for this compound. In the 1980s, the EPA set a reference dose of up to 50 mcg/kg per day in the United States and considers intake below this dose to be safe for health. European and American regulatory agencies have maintained that exposure to BPA from polycarbonates and epoxy resins poses no health risk.
In 2021, the European Food Safety Authority (EFSA) re-evaluated its safety consumption level for bisphenol A to one that was 20,000 times reduced. Stemming from the EFSA action, in 2022, American environmental and health groups petitioned the U.S. Food and Drug Administration (FDA) to either ban or reassess its recommendations for authorized limits for bisphenol A. In October 2022, the FDA agreed to conduct this review. In June 2024, the European Union Expert Committee approved a ban on bisphenol A. A similar action by the FDA was still under review and had yet to materialize.
Bibliography
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