This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study has found that chemicals that can affect fertility and reproductive health are contaminating natural and drinking water supplies. The researchers involved in the study have also developed a tool to help detect them.
They analyzed samples from natural waterways, tap water, bottled water, tank water and rainwater and found hormone-disrupting substances—estrogenic endocrine-disrupting chemicals—in many of them. The research is published in the journal iScience. Senior author Alison Heather, a professor in the University of Otago—Ōtākou Whakaihu Waka Department of Physiology and chief scientific officer of biotech startup InsituGen, says these chemicals are linked to ecological harm and human health effects, including declining fertility and reproductive health.
"This doesn't mean all water is unsafe to drink, but it does show that detectable estrogen-like signals are present in many common water sources, while other sources are essentially free of such activity. "It highlights both the scale of environmental contamination and the fact that cleaner, low-estrogenic water sources are achievable. "For example, we found strong estrogenic activity in some rivers, household tap water, certain tanks and one brand of bottled water, whereas one spring, one filtered fountain and one bottled product showed no detectable estrogenic activity," says Heather.
Current water monitoring techniques test for only a handful of chemicals, but the researchers have developed an easy-to-use, sensitive bioassay that measures the concentration of estrogenic contaminants. "Environmental samples typically contain complex mixtures of natural hormones, pharmaceutical estrogens, pesticides, plasticizers and other industrial chemicals, but it is the combined biological effect of these mixtures that ultimately matters," Heather explains. "This new tool can help identify where mixtures of endocrine-disrupting chemical contaminants are highest so that public health regulators and water suppliers can act to reduce exposures over the long term." While the study did not directly measure health outcomes, Heather says it reinforces the need to treat estrogenic endocrine-disrupting chemicals as a long-term ecological and public health issue.
"Over the same decades that environmental chemical use has increased, many high-income countries have seen total fertility rates fall to well below replacement level, driven by a complex mix of social, economic and biological factors. "In parallel, several studies have reported substantial declines in sperm concentration and total sperm count among men in Western countries over the last 40–50 years. While these trends cannot be attributed to endocrine-disrupting chemicals alone, they are consistent with broader concerns that chronic low-dose exposure to mixtures of such chemicals may be one of multiple contributors to impaired reproductive health." Heather believes endocrine bioactivity testing needs to be incorporated into routine water-quality monitoring, alongside conventional chemical analyses and microbiological measures.
Because the study shows it is possible to provide water with no detectable estrogenic activity, she would also like water supplies, including bottled water, to be benchmarked against this standard. "Using bioassays such as ours, in conjunction with high-resolution mass spectrometry, can help identify specific contributing chemicals, such as certain plasticizers, pesticides or steroid hormones, and guide changes in source protection, treatment processes and packaging choices. "Regular monitoring of estrogenic activity in water sources is critical to addressing this global issue." Gihani Manodara et al, Functional estrogenic activity in rivers, water supply, and rainwater, iScience (2026).
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