Bisphenol A, or BPA, is a widely used chemical compound that’s added to a massive range of commercial products across almost every industry. Since it is colorless and completely soluble, it is commonly used in manufacturing polycarbonate plastics and epoxy resins for containers that store food and beverages.
Studies have shown BPA to be a reproductive and developmental toxin in animals as well as an endocrine (hormone) disruptor, meaning it can imitate the body’s natural hormones and interfere with their normal functions.
Most of us probably associate BPA with hard plastic products like reusable water bottles, but the chemical compound has snuck its way into a whole range of everyday items. Once a staple in infant products like baby bottles, baby food containers, and pacifiers, many manufacturers have stopped using it. Canned food, however, is now perhaps the most notorious for BPA exposure, as it’s often used for the protective plastic liners of the cans themselves and can leach into food. It can also be found in shatterproof windows, eyewear, bottle tops, water supply pipes, and more.
The FDA, an agency considered to be laxer than its EU counterpart, has remained firm in its stance that there are no risks of health effects at normal consumer exposure levels (the agency released its most recent assessment of the chemical in 2014).
The U.S. Environmental Protection Agency (EPA), however, says that the concentration of BPA levels linked to negative effects in laboratory animals are similar to those to which sensitive aquatic organisms are currently exposed in the natural environment. The agency admits that more than 1 million pounds of BPA are released into the environment every year.
History of BPA
Evidence of BPA mimicking the human hormone estrogen dates back to the 1930s, but it wasn’t until 1993 that researchers at Stanford University found evidence that tiny particles of the synthetic chemical could leach out of these plastic products to potentially interfere with environmental health.
The discovery came at a time when endocrine disruptors were growing in attention. Just two years earlier in 1991, the World Wildlife Fund organized a meeting of wildlife biologists, endocrinologists, reproductive physiologists, and toxicologists to issue a consensus statement that “a large number of man-made chemicals had been released into the environment that were capable of disrupting the endocrine systems of wildlife and humans.”
Back in 2004, the National Health and Nutrition Examination Survey conducted by the Centers for Disease Control and Prevention (CDC) detected levels of BPA in 93% of people aged six and older. A more recent study of 94 teenagers from southwestern England found that 86% had traces of BPA in their systems after avoiding BPA products for seven days straight.
In 2012, the FDA agreed to a partnered study known as the Consortium Linking Academic and Regulatory Insights on BPA Toxicity, or “CLARITY-BPA,” in response to public concern about widespread exposure. The $30 million, seven-year project involved experiments on 3,800 rats, exposing part of the group to BPA using the controversial oral gavage technique (a horrific process in which animals are dosed with chemicals by sticking feeding tubes down their throats). Some scientists warned that the invasive daily testing would stress the rats out in such a way that could skew the results.
When the FDA released its report on the core study in 2018, they found that lower-dose effects of BPA “were not dose responsive, sometimes occurring in only one low or intermediate dose group, and did not demonstrate a clear pattern of consistent responses within or across organs within the stop- and continuous-dose arms and sacrifice times.”
However, other researchers involved in the study published reports of their own findings, including one that demonstrated how BPA could alter gene expressions in the developing brain of newborn rats even at doses below the no-observed-adverse-effect level.
Another paper that came as a result of the study found that low-level BPA exposure could contribute to an increased risk of prostate cancer in humans and animals later in life.
Alternatives to BPA
BPA substitutions, which include bisphenol S (BPS) and diphenyl sulfone, may be just as bad for the environment. These alternatives have similar structures to BPA and thus appear to pose similar potential health hazards.
Research in pregnant female mice fed low doses of BPA, BPS, diphenyl sulfone, or placebos found that those exposed to BPA or its alternatives showed the same genetic damage that could trigger miscarriage or reduce sperm count.
BPA and the Environment
Environmentally, a huge concern lies in BPA’s adverse effects on the endocrine system of wildlife when it enters the environment in regions with large plastic-producing industries. Researchers detected BPA pollution in 100% of over 120 water and surface soil samples from two cities with extensive plastic factories in China—the world’s largest manufacturers of plastic. This is especially concerning, as about 27 million BPA-containing plastic products are produced each year globally.
As is the case with many chemicals, rivers, and lakes represent some of the largest sinks for BPA, which can affect aquatic vertebrates like fish and amphibians, but also animals that live in surrounding environments like reptiles and birds. This damage to wildlife can have a trickle-down effect to damage the entire ecosystem.
BPA has also been found to disrupt sexual function in turtles by altering their reproductive systems and sexual differentiation. Turtle species typically yield more females when eggs are developed in warmer temperatures, but when eggs are exposed to environmental estrogens, their sex is determined by the chemicals rather than the climate. Certain doses of BPA can also significantly inhibit the growth of algae and the efficiency of photosynthesis in terrestrial plants. Even worse, a 2019 study in the journal Reproductive Biology and Endocrinology found evidence that hormone interference from BPA could even be transmitted to further generations in animals.
BPA pollution doesn’t just show up in plastics industry areas, either, but also in places where plastic waste containing BPA is disposed of, including wastewater treatment plants and landfill sites. When a plastic product—anything from food containers to water bottles to canned food—made using BPA additives reaches the end of its life, there’s a high chance it will end up in the trash or ocean. In fact, the highest amounts of BPA (up to 17 milligrams per liter) are reported in landfill leachate (the highly toxic liquid byproduct of landfill waste) and liquid waste from paper mills.
There are no federal bans when it comes to BPA outside of baby products, although certain states like Washington, Wisconsin, and Vermont have put their own measures into place that restrict or prohibit the sale of certain products containing BPA. In 2015, California listed BPA as a reproductive toxicant as part of Prop. 65, requiring consumer products to carry a warning label if BPA levels exceed a “safe harbor level.” The European Union strengthened limitations on BPA in 2016 following new scientific data, reclassifying it to a higher level of reprotoxic category and restricting its use in thermal paper.
Currently, the FDA considers the approved uses of BPA in food containers and packaging to be safe, reassuring consumers that the agency has “performed extensive research and reviewed hundreds of studies about BPA’s safety,” as well as “…continues to monitor the scientific literature for new research that helps enhance our understanding of BPA, and will consider new data as it continues to ensure the safe use of BPA in food packaging.” However, some studies suggest that the FDA has vastly underestimated levels of widespread BPA exposure, and that the measurements relied upon by the regulatory agency could be off by as much as 44 times.