Health effects lining of metal food and beverage cans, and
plastic bottles. In 2017 the
European Chemicals Agency concluded that BPA should be listed as a substance of very high concern due to its properties as an
endocrine disruptor. In 2023, the
European Food Safety Authority re-evaluated the safety of BFA and significantly reduced tolerable daily intake (TDI) to 0.2 nanograms (0.2 billionths of a gram), 20,000 times lower than the previous TDI from 2015. The European Food Safety Authority concluded that consumers with both average and high exposure to BPA in all age groups exceeded the new TDI, indicating health concerns. In 2012, the United States'
Food and Drug Administration (FDA) banned the use of BPA in
baby bottles intended for children under 12 months. The FDA maintains that the agency continues to support the safety of BPA for use in products that hold food. In 2011, Andrew Wadge, the chief scientist of the United Kingdom's
Food Standards Agency, commented on a 2011 U.S. study on dietary exposure of adult humans to BPA, saying, "This corroborates other independent studies and adds to the evidence that BPA is rapidly absorbed, detoxified, and eliminated from humans – therefore is not a health concern." The
Endocrine Society said in 2015 that the results of ongoing laboratory research gave grounds for concern about the potential hazards of
endocrine-disrupting chemicals – including BPA – in the environment, and that on the basis of the
precautionary principle these substances should continue to be assessed and tightly regulated. A 2016 review of the literature said that the potential harms caused by BPA were a topic of scientific debate and that further investigation was a priority because of the association between BPA exposure and adverse human health effects including reproductive and developmental effects and metabolic disease.
United States expert panel conclusions In 2007, the U.S. federal government invited experts to Chapel Hill, North Carolina to perform a scientific assessment of literature on BPA. Thirty-eight experts in fields involved with bisphenol A gathered in
Chapel Hill, North Carolina to review several hundred studies on BPA, many conducted by members of the group. At the end of the meeting, the group issued the Chapel Hill Consensus Statement, which stated "BPA at concentrations found in the human body is associated with organizational changes in the prostate, breast, testis, mammary glands, body size, brain structure and chemistry, and behavior of laboratory animals." In 2009, the FDA Science Board Subcommittee on Bisphenol A, an external committee assigned to review the FDA's report "concluded that the FDA failed to conduct a rigorous or extensive exposure assessment", leading the US Environmental Protection Agency (EPA) to conduct their own assessment.
Metabolic disease Numerous animal studies have demonstrated an association between endocrine disrupting chemicals (including BPA) and obesity. However, the relationship between bisphenol A exposure and obesity in humans is unclear. Cohort studies have shown there has been an association of prenatal BPA exposure and increased body fat percentage at age 7 and increased BMI by age 9. Not all studies have shown a positive relationship between BPA exposure and obesity, further studies on the effects of BPA on metabolic diseases need to take diet into consideration to remove any influence it might have on the outcome. BPA works by imitating the natural hormone
17B-estradiol. In the past BPA has been considered a weak mimicker of
estrogen but newer evidence indicates that it is a potent mimicker. When it binds to estrogen receptors it triggers alternative estrogenic effects that begin outside of the nucleus. This different path induced by BPA has been shown to alter glucose and lipid metabolism in animal studies. There are different effects of BPA exposure during different stages of development. During adulthood, BPA exposure modifies insulin sensitivity and insulin release without affecting weight.
Thyroid function and concluded that "available evidence suggests that governing agencies need to regulate the use of thyroid-disrupting chemicals, particularly as such uses relate exposures of pregnant women, neonates and small children to the agents". A 2009 review summarized BPA adverse effects on thyroid hormone action. A 2016 case control study found that there was a significant association between urinary BPA levels and increased TSH levels (Thyroid- stimulating hormone) in a group of adult women.
Neurological effects Limited epidemiological evidence suggests that exposure to BPA in the uterus and during childhood is associated with poor behavioral outcomes in humans. Exposure may be associated with higher levels of anxiety, depression, hyperactivity, and aggression in children. A panel convened by the National Toxicology Program (NTP) of the U.S.
National Institutes of Health determined that there was "some concern" about BPA's effects on fetal and infant brain development and behavior. In January 2010, based on the NTP report, the FDA expressed the same level of concern. A 2007 literature review concluded that BPA, like other chemicals that mimic estrogen (xenoestrogens), should be considered as a player within the nervous system that can regulate or alter its functions through multiple pathways. A 2008 review of animal research found that low-dose BPA maternal exposure can cause long-term consequences for the neurobehavioral development in mice. in the
hippocampus and even nanomolar (10−9
mol) dosage could induce significant effects on memory processes. A 2009 review raised concerns about a BPA effect on the
anteroventral periventricular nucleus.
Disruption of the dopaminergic system dopamine activity resulting in
hyperactivity,
attention deficits, and a heightened sensitivity to
drugs of abuse. A 2008 review of human participants has concluded that BPA mimics estrogenic activity and affects various dopaminergic processes to enhance mesolimbic dopamine activity resulting in hyperactivity, attention deficits, and a heightened sensitivity to drugs of abuse. A 2010 review concluded that bisphenol A may increase cancer risk. Several studies show evidence that the formation of prostate cancer in men is directly proportional to BPA exposure. Male subject diagnosed with prostate cancer were found to have higher urine concentration of BPA as opposed to the concentrations found in the control group's. This correlation may be due to BPA's ability to induce cell proliferation of the prostate cancer cells.
Breast cancer Higher susceptibility to breast cancer has been found in many studies of rodents and primates exposed to BPA. More
oxidative stress in breast cancer cells were found to be directly proportional to BPA exposure as per the findings in several in vitro studies.
Mechanism of action BPA is an endocrine disruptor, meaning BPA has a similar structure to
oestrogen (ligand) and can bind to the oestrogen receptor
ERα and
ERβ and activate it. Oestrogen is hydrophobic and is able to diffuse through the plasma membrane and into the target cell. Oestradiol binding to the oestrogen receptor releases the heat shock protein from the ligand binding domain of the receptor causing dimerization. The nuclear localisation signal targets the ligand-receptor complex to the nucleus where it can bind oestrogen response elements within the promoter of target genes on DNA. Subsequently, various cofactors are recruited allowing transcription of genes including those involved in cell proliferation. When BPA is exposed to high temperatures or changes in pH, the ester bond linking BPA monomers is hydrolysed. Free BPA then competes with oestrogen for ERα and ERβ binding sites. When BPA successfully binds the receptor, it interacts with ERE and increases expression of target genes like WNT-4 and RANKL; two key players in stem cell proliferation and carcinogenesis. BPA was also shown to inactivate
p53 which prevents tumour formation as it triggers apoptosis.
Fertility As of 2022, current evidence shows a possible positive correlation between BPA levels, lower sperm quality, decreased motility and an increase in sperm immaturity. There is tentative evidence to support the idea that BPA exposure has negative effects on human fertility. warrants the continued research of BPA for couple fecundity. Ubiquitous in environment through consumer products such as reusable plastics, food and beverage container liners, baby bottles, water resistant clothing. It has been identified as an EDC and found in urine, blood, amniotic fluid, breast milk and cord blood. Comparing blood BPA and phthalate levels between fertile and infertile women between the ages of 20–40, using gas chromatographic-mass spectrometry to analyze the amount of BPA, phthalate and their metabolites in peripheral venous blood, showed significantly elevated serum BPA level in infertile women, as well as women with PCOS (polycystic ovarian syndrome) and women with endometriosis BPA is shown to have transgenerational effect by targeting ovarian function by changes in the structural integrity of microtubules that constitute meiotic spindles. BPA contaminants pass through amniotic fluid can alter steroidogenesis in fetal development. This will result if oocyte maturation failure as well as fertility This in turn will result in transgenerational effect and affect the third generation of offspring
Sexual function Higher BPA exposure has been associated with increased self-reporting of decreased male sexual function but few studies examining this relationship have been conducted. A study published in JAMA Pediatrics has found that prenatal exposure to BPA is also linked to lower lung capacity in some young children. This study had 398 mother-infant pairs and looked at their urine samples to detect concentrations of BPA. They study found that every 10-fold increase in BPA was tied to a 55% increase in the odds of wheezing. The higher the concentration of BPA during pregnancy were linked to decrease lung capacity in children under four years old but the link disappeared at age 5. Associate professor of pediatrics at the
University of Maryland School of Medicine said, "Exposure during pregnancy, not after, appears to be the critical time for BPA, possibly because it's affecting important pathways that help the lung develop." In 2013, research from scientists at the Columbia Center for Children's Environmental Health also found a link between the compound and an increased risk for asthma. The research team reported that children with higher levels of BPA at ages 3, 5 and 7 had increased odds of developing asthma when they were between the ages of 5 and 12. The children in this study had about the same concentration of BPA exposure as the average U.S. child. Dr. Kathleen Donohue, an instructor at Columbia University Medical Center said, "they saw an increased risk of asthma at fairly routine, low doses of BPA." Kim Harley, who studies environmental chemicals and children's health, commented in the
Scientific American journal saying while the study does not show that BPA causes asthma or wheezing, "it's an important study because we don't know a lot right now about how BPA affects immune response and asthma...They measured BPA at different ages, measured asthma and wheeze at multiple points, and still found consistent associations." Early developmental stages appear to be the period of greatest sensitivity to its effects, A study from 2008 concluded that blood levels of bisphenol A in neonatal mice are the same whether it is injected or ingested. The current U.S. human exposure limit set by the EPA is 50 μg/kg/day. and a later editorial by the same journal, which claimed the rats used in the study were insensitive to estrogen and that had other problems like the use of BPA-containing polycabonate cages while the authors disagreed. Different expression of ERR-γ in different parts of the body may account for variations in bisphenol A effects. For instance, ERR-γ has been found in high concentration in the
placenta, explaining reports of high bisphenol accumulation in this tissue. BPA can be released into the environment by both pre-consumer and post-consumer leaching. Common routes of introduction from the pre-consumer perspective into the environment are directly from chemical plastics, coat and staining manufacturers, foundries who use BPA in casting sand, or transport of BPA and BPA-containing products . Post-consumer BPA waste comes from effluent discharge from municipal wastewater treatment plants, irrigation pipes used in agriculture, ocean-borne plastic trash, indirect leaching from plastic, paper, and metal waste in landfills, and paper or material recycling companies. Despite a rapid soil and water
half-life of 4.5 days, and an air half-life of less than one day, BPA's ubiquity makes it an important
pollutant. BPA has a low rate of evaporation from water and soil, which presents issues, despite its
biodegradability and low concern for bio-accumulation. BPA has low
volatility in the atmosphere and a low
vapor pressure between 5.00 and 5.32 Pascals. BPA has a high
water solubility of about 120 mg/L and most of its reactions in the environment are
aqueous. An interesting fact is that BPA dust is flammable if ignited, but it has a minimal explosive concentration in air. Also, in aqueous solutions, BPA has shown absorption of wavelengths greater than 250 nm. A 2013 study also observed changes in plant health due to BPA exposure. The study exposed
soybean seedlings to various concentrations of BPA and saw changes in root growth,
nitrate production,
ammonium production, and changes in the activities of
nitrate reductase and
nitrite reductase. At low doses of BPA, the growth of roots were improved, the amount of nitrate in roots increased, the amount of ammonium in roots decreased, and the nitrate and nitrite reductase activities remained unchanged. However, at considerably higher concentrations of BPA, the opposite effects were seen for all but an increase in nitrate concentration and a decrease in nitrite and nitrate reductase activities. Nitrogen is both a plant nutritional substance, but also the basis of growth and development in plants. Changing concentrations of BPA can be harmful to the ecology of an ecosystem, as well as to humans if the plants are produced to be consumed. The amount of absorbed BPA on sediment was also seen to decrease with increases in temperature, as demonstrated by a study in 2006 with various plants from the
XiangJiang River in Central-South China. In general, as temperature increases, the water solubility of a compound increases. Therefore, the amount of sorbate that enters the solid phase will lower at the
equilibrium point. It was also observed that the adsorption process of BPA on sediment is exothermic, the molar formation
enthalpy,
ΔH°, was negative, the free energy
ΔG°, was negative, and the molar
entropy,
ΔS°, was positive. This indicates that the
adsorption of BPA is driven by enthalpy. The adsorption of BPA has also been observed to decrease with increasing
pH. A 2005 study conducted in the United States had found that 91–98% of BPA may be removed from water during treatment at municipal water treatment plants. A more detailed explanation of aqueous reactions of BPA can be observed in the Degradation of BPA section below. Nevertheless, a 2009 meta-analysis of BPA in the surface water system showed BPA present in surface water and sediment in the United States and Europe. According to
Environment Canada in 2011, "BPA can currently be found in municipal wastewater. […]initial assessment shows that at low levels, bisphenol A can harm fish and organisms over time." BPA affects growth, reproduction, and development in aquatic organisms. Among freshwater organisms, fish appear to be the most sensitive species. Evidence of endocrine-related effects in fish, aquatic invertebrates, amphibians, and reptiles has been reported at environmentally relevant exposure levels lower than those required for acute toxicity. There is a widespread variation in reported values for endocrine-related effects, but many fall in the range of 1μg/L to 1 mg/L. ==Vertebrates==