Water bottles, lipsticks, receipts, and tinned food cans. Have you ever considered what may be lurking in these seemingly harmless daily essentials? These items all contain bisphenol A (BPA), a common endocrine-disrupting chemical (EDC). EDCs are chemicals that mimic or interfere with the endocrine system, which is responsible for producing and releasing hormones that regulate important processes in the body such as growth, metabolism, and reproduction (The Endocrine Society & IPEN, 2024). Upon being released into the bloodstream, hormones travel to their target tissues and organs, where they influence key biological functions. Hormones have specific receptors on their surface which bind to matching receptors on their target tissue.
The endocrine system is an incredible feat of nature. It creates widespread and long-lasting changes throughout the body via an intricately controlled web of interactions between tiny molecules. However, a small change can be enough to tip this finely regulated balance into disarray. BPA is a type of bisphenol, which is one class among many other types of EDCs, such as phthalates, perfluoroalkyl substances (PFAS), and polychlorinated biphenyls (PCBs). BPA has a similar chemical structure to oestrogen, an important hormone involved in both male and female reproductive systems. This enables BPA to ‘mimic’ oestrogen; essentially tricking oestrogen receptors into activating in the absence of oestrogen. BPA is known to cause a wide range of negative health impacts, such as reproductive, metabolic, and neurological issues (The Endocrine Society & IPEN, 2024).
But don’t just take my word for it. The toxicity of BPA has been debated over many decades, ever since it was first linked to health issues in the 1970s. It has been challenging to generate evidence relating to the toxicity of BPA, given the ethical concerns of deliberately exposing people to EDCs. As a result, scientists have mainly used animal models, alongside studies examining the correlation between EDC exposure and disease, to investigate the action of BPA. Research strongly indicates that elevated exposure to BPA is correlated with poorer egg quality and higher miscarriage rates in women, alongside a reduction in sperm count in men (Matuszczak et al., 2019). BPA is also a known obesogen (a hormone which disrupts metabolism, increasing risk for obesity), supported by a recent study indicating the odds of adult obesity rise by 15% for every 1 nanogram/mL increase in the concentration of their urinary BPA (Wu et al., 2020).
Even more concerningly, BPA has been found to have epigenetic effects, which are heritable chemical modifications to DNA which regulate how genes are turned on and off. Scientists were able to demonstrate these epigenetic effects by exposing rats to BPA and allowing them to breed for multiple generations. In this study, rates of obesity and reproductive disease were increased in all subsequent generations of rats, despite only the first generation being directly exposed to BPA (Manikkam et al. 2013). Considering that BPA has been used commercially since the 1950s, it is probable that these epigenetic effects have been compounding in humans with each passing generation. Without intervention, the consequences of ongoing BPA exposure are likely to intensify.
It is deeply concerning that BPA remains ubiquitous in the community, with more than 7 million tonnes produced each year (Manzoor et al., 2022). Given its presence in a multitude of everyday products, BPA exposure is essentially impossible to avoid. Detectable levels of BPA are present in nearly all children and adults, and even developing foetuses (Calafat et al., 2004). Mounting evidence for the toxicity of BPA is prompting scientists to call for greater measures in preventing harmful exposure to BPA and other EDCs.
What is being done by policy makers to address this issue? I sat down with A/Prof Mark Green, an Associate Professor in Reproductive Biology at the University of Melbourne, to discuss the current research around EDCs and the measures that can be taken to protect the public from their damaging effects.
Are BPA-free labels just illusions of safety?
There has been a shift towards manufacturing products labelled ‘BPA-free’, such as BPA-free water bottles. This sounds great on the surface: purchase the ‘BPA-free’ water bottle and sleep well knowing that you’re taking proactive action to protect your health. Unfortunately, these efforts may be in vain. As companies manufacturing EDC-containing items have a vested interest in their products being approved as safe, many of these ‘BPA-free’ products are simply being replaced with other bisphenols (e.g. bisphenol F, or BPF), which are suspected to have similar or even worse effects compared to BPA (Wiklund & Beronius, 2022).
Fortunately, some countries have started looking towards more holistic ways of regulating suspected EDCs, as noted by A/Prof Green:
‘A positive step forward is that the USA and EU are starting to think about regulating whole classes of chemicals, rather than individual chemicals.’
Introducing this new approach will help to ensure that manufacturers can’t simply switch to a similar (but unregulated) chemical when one is banned.
Redefining toxicity: Does the dose make the poison?
Another key issue is the current way that EDCs are evaluated for toxicity. A historical principle of toxicology (which has later been challenged) is the idea that ‘the dose makes the poison’. This theory proposes that substances with ‘toxic’ properties only cause us harm if we are exposed to a certain ‘threshold’ amount. In other words, if someone is exposed to five times the amount of a chemical, they will observe five times as much of an effect on their health. However, scientists have found that many EDCs don’t behave in this way. There are some instances where lower doses may, in fact, lead to more severe effects. As A/Prof Green aptly puts, there may be no such thing as a ‘safe dose’ for some EDCs.
Blind spots in EDC regulatory testing: Are vulnerable populations overlooked?
Regulatory testing procedures often underestimate the negative impact of EDCs by disregarding how hormones affect people differently throughout the lifespan. Embryonic development is a critical period in which exposure to EDCs can have disproportionately large impacts on health compared to exposure in adults. Choi and colleagues (2016) studied the consequences of BPA exposure on developing cattle embryos and observed that even short-term exposure had concerning repercussions on their development and metabolism. Nost testing procedures fail to take these endpoint measures into account. A/Prof Green pointed to examples of toxicology testing in which ‘rates of death and tumours in adult male rats were used as an end point measure to define toxicity, which had nothing to do with more subtle effects on reproduction’.
Context matters: Navigating EDC regulation in the real world
Another factor to consider is that these individual EDCs don’t exist in a vacuum; the reality is that we are exposed to a ‘soup’ of many different chemicals every day. A/Prof Green noted the inefficiency of testing individual chemicals for endocrine-disrupting properties:
‘Historically a lot of these EDCs have been studied individually, but we don’t know what happens with all the different compounds when they go together, and which combinations are worse. Investigating EDC mixtures is a big gap of knowledge.’
In isolation, small doses of EDCs may not result in any adverse impacts on human health. That said, the interaction of many EDCs may have severe consequences (Conley et al., 2021). These interactions may explain the conflicting evidence surrounding EDCs, where some studies reveal significant effects and others do not. A/Prof Green is currently investigating the impacts of EDC mixtures on human health in relation to the ‘exposome’, which is the cumulative effect of the environmental exposures we encounter throughout our lives (e.g. chemicals, air pollutants, radiation, food). He hopes that a better understanding of these complex interactions will allow us to make more informed decisions about how to regulate EDCs.
Paving the path towards a healthier future
Unfortunately, the economic interests of companies producing EDC-containing products compete with the implementation of necessary policies. Given the suspected epigenetic effects of EDCs like BPA, taking a more cautious but proactive approach in regulating EDCs seems to be a wise course of action. The burden created by EDCs is huge, with attributable annual disease costs estimated to be $340 billion USD in the USA, and $217 billion USD in the EU (Malits et al., 2022).
What can we do as consumers? Are we resigned to bathing in a cocktail of EDCs, awaiting our descent into a dystopian nightmare reminiscent of ‘The Handmaid’s Tale’?
Despite the disheartening reality of EDCs, there is room for hope. Scientists are working hard to find safer alternatives to materials containing EDCs, and a growing number of chemicals are facing bans or stricter regulation.
The first step in mitigating the negative consequence of these chemicals is increasing awareness about EDCs and reducing our personal exposure to them.
Here are 5 tips from A/Prof Green that can help you to avoid unnecessary exposure to EDCs:
1. Don’t drink from plastic water bottles, especially if they have been left in a hot environment.
2. Don’t reheat food in plastic containers - use a microwave-safe bowl or plate instead. When storing leftover food, let it cool before transferring to plastic containers.
3. Try to reduce consumption of tinned foods, as these are lined with plastic resins.
4. Avoid handling receipts, as these are covered in BPA.
5. Ventilate your home and avoid perfumes or sprays with strong smells – these often contain EDCs.
To encourage governments and industrial regulators to enforce stronger legislation and tighter controls on EDCs, it is essential to empower consumers and advance scientific research. While our direct influence on policy decisions may be limited, as consumers, we possess the power to drive positive change, promoting public health not only in the present but for generations to come.
For some more information, check out these great resources about EDCs:
https://www.yourfertility.org.au/everyone/drugs-chemicals
https://endocrinedisruption.org/
References
Calafat, A. M., Kuklenyik, Z., Reidy, J. A., Caudill, S. P., Ekong, J., & Needham, L. L. (2005). Urinary concentrations of bisphenol A and 4-nonylphenol in a human reference population. Environmental Health Perspectives, 113(4), 391-395. https://doi.org/10.1289/ehp.7534
Choi, B. I., Harvey, A. J., & Green, M. P. (2016). Bisphenol A affects early bovine embryo development and metabolism that is negated by an oestrogen receptor inhibitor. Scientific Reports, 6(1), 29318. https://doi.org/10.1038/srep29318
Conley, J. M., Lambright, C. S., Evans, N., Cardon, M., Medlock-Kakaley, E., Wilson, V. S., & Gray Jr, L. E. (2021). A mixture of 15 phthalates and pesticides below individual chemical no observed adverse effect levels (NOAELs) produces reproductive tract malformations in the male rat. Environment International, 156, 106615. https://doi.org/10.1016/j.envint.2021.106615
Gore, A.C., La Merrill, M.A., Patisaul, H.B., and Sargis, R. (2024). Endocrine Disrupting Chemicals: Threats to Human Health. The Endocrine Society and IPEN. https://ipen.org/sites/default/files/documents/edc_report-2024-final-compressed.pdf
Malits, J., Naidu, M., & Trasande, L. (2022). Exposure to endocrine disrupting chemicals in Canada: population-based estimates of disease burden and economic costs. Toxics, 10(3), 146. https://doi.org/10.3390/toxics10030146
Manikkam, M., Tracey, R., Guerrero-Bosagna, C., & Skinner, M. K. (2013). Plastics derived endocrine disruptors (BPA, DEHP and DBP) induce epigenetic transgenerational inheritance of obesity, reproductive disease and sperm epimutations. PloS One, 8(1), e55387. https://doi.org/10.1371/journal.pone.0055387
Manzoor, M. F., Tariq, T., Fatima, B., Sahra, A., Tariq, F., Munir, S., Khan, S., Ranhja, M. M. A. N., Sameen, A., Zeng, X., & Ibrahim, S.A. (2022). An insight into bisphenol A, food exposure and its adverse effects on health: A review. Frontiers in Nutrition, 9. https://doi.org/10.3389/fnut.2022.1047827
Matuszczak, E., Komarowska, M. D., Debek, W., & Hermanowicz, A. (2019). The impact of bisphenol A on fertility, reproductive system, and development: a review of the literature. International Journal of Endocrinology, 2019. https://doi.org/10.1155/2019/4068717
Wu, W., Li, M., Liu, A., Wu, C., Li, D., Deng, Q., Zhang, B., Du, J., Gao, X., & Hong, Y. (2020). Bisphenol A and the risk of obesity a systematic review with meta-analysis of the epidemiological evidence. Dose-Response, 18(2). https://doi.org/10.1177/1559325820916949
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