A new scientific study released to the public shows that the overall mix of chemicals entering the human body can significantly reduce male sperm quality in unexpected ways.
Substances such as bisphenols and dioxins are believed to disrupt hormones and harm sperm quality, and fresh research indicates that these compounds may be present at levels up to 100 times higher than those considered safe.
Bisphenol A BPA is identified as the chemical producing the greatest risk, drawing attention from researchers in results reported by the Guardian. This chemical often leaches from the linings of food cans and is found in some milk products and packaged foods.
The researchers note that crucial steps in healthy male sexual development occur during pregnancy, which makes the study findings especially relevant for expectant families.
50% fewer sperm in 40 years
Scientists have long warned that sperm count and concentration have declined sharply in Western nations, with some data showing a halving of sperm count over the past four decades. Other male sexual health issues such as penile malformations, breast cancer, and undescended testes are appearing more often. Hormone-disrupting chemicals are viewed as the main suspect in this trend, and the study provides new context about chemical cocktails that may harm male reproductive health.
Bisphenols are frequently present in canned foods and related products, a finding supported by visual materials accompanying the study.
The study team, led by Professor Andreas Kortenkamp of Brunel University London, described being stunned by the magnitude of the hazard index, a metric measuring risk from chemical mixtures. The researchers also noted BPA as the chemical of most concern, challenging prior focus on phthalates used in plastics.
Kortenkamp suggested that the research will enable more robust epidemiological work to assess effects in humans. He advised that with the current evidence there is little reason to delay regulatory action.
Research published in Environment International evaluated measurements of nine chemicals including bisphenols, phthalates, and acetaminophen in urine samples from nearly 100 Danish men aged 18 to 30. It also used available data, largely from European food safety authorities, to estimate exposure to 20 other chemicals.
These data were compared with accepted exposure levels, drawn from scientific literature, to estimate a potential impact for each chemical. An established method combined these into an overall risk score for the cocktail of chemicals in each man. All participants showed combined exposures above safe levels, with the most exposed individuals reaching levels up to 100 times acceptable and averaging 17 times above. The researchers stated that their assessment reveals alarming excesses of acceptable exposures.
The most problematic compounds
The researchers were able to categorize the chemicals by risk: dioxins, paracetamol, and phthalates rank behind BPA as major risk factors. However, removing BPA did not reduce the overall exposure to safe levels.
Paracetamol is linked to decreased sperm quality and higher risks of undescended testes in laboratory animals and in children whose mothers used analgesics during pregnancy. A 2021 review supported by a broad panel of scientists cautioned pregnant women in early pregnancy about paracetamol use unless medically indicated and advised consultation with a doctor or pharmacist when unsure.
The study team acknowledged uncertainties in their analysis. For example, the data cover 2009 to 2010, and while BPA exposure has declined somewhat since then, exposure to other bisphenols has risen. It is also possible that the exposure patterns of young women differ from those of young men in the study. Nevertheless, the overall takeaway remains clear: given the large number of chemicals people encounter, the risks of chemical mixtures may be underestimated. PFAS, often called forever chemicals, are known to affect sperm but were not included due to data limitations. Air pollution is also associated with reduced sperm quality.
Besides chemical exposure, researchers have proposed other factors that may contribute to decreasing sperm quality, including body weight, physical activity levels, and smoking.
Overall, the researchers emphasize that chemicals are not the sole factor. Kortenkamp notes that nutrition and diet also play a role; epidemiologists warn that high-fat foods may negatively affect sperm quality.
Professor Hagai Levine of the Hebrew University School of Public Health remarked that the study adds to a growing body of evidence on the adverse effects of specific chemicals on human reproduction and called for stronger global investigative efforts into the causes of male reproductive health issues.
In contrast, Professor Richard Sharpe of the University of Edinburgh expressed skepticism about the causal role of weak endocrine-active environmental chemicals. He highlighted that the study did not test all potential agents like acetaminophen and warned that there is no direct evidence that many ingested chemicals cause direct harm to testicular development. Sharpe argued that environmental factors likely contribute to the observed decline, but noted that a high-fat, processed diet is itself harmful and could be the primary source of some chemicals, making it difficult to pinpoint a single culprit. He also acknowledged that chemical cocktails can negatively affect sperm count in men.
The Guardian covered the study with emphasis on the cocktail of pollutants and their potential link to falling sperm quality. The article discussed reactions from multiple experts and framed the results as a prompt for further research and policy consideration.
Researchers did not rely on a single source for their conclusions; the work synthesized data from multiple streams to provide a broad view of how chemical exposure may influence male reproductive health. The study underscores the need for ongoing monitoring and careful regulation of environmental chemicals that people encounter daily.