Chemicals such as bisphenols and dioxins are thought to interfere with hormones and impair sperm quality, and the study found that combinations of these compounds are present in “amazing” levels, up to 100 times greater than what is considered safe. Bisphenol A (BPA) was responsible for the higher risks, scientists said. The chemical is found in milk and canned foods as it flushes out of packaging packaging. The key steps to healthy male sexual development occur during pregnancy, making the results of the study particularly important for expectant mothers, the researchers said. Sperm counts and concentrations have plummeted alarmingly in western countries for decades, scientists say, with sperm counts halved in the last 40 years. Other male sexual disorders such as penile dysplasia, breast cancer and undescended testicles have increased. Hormone-disrupting chemicals are a major suspect, and the study sheds new light on the possibility that chemical cocktails can cause harm. The study team, led by Professor Andreas Kortenkamp at Brunel University in London, said they were “surprised by the size of the risk index”, the measure of the risk of chemical cocktails. The team was also surprised that BPA was the most worrying chemical, as previous work had focused on phthalates used in plastics. Kortenkamp told the Guardian that the research would allow better epidemiological studies to be conducted in humans to assess the effects. “But I personally believe that, with the information we have provided, there is no reason to delay any regulatory action.” The study, published in the journal Environment International, evaluated measurements of nine chemicals, including bisphenol A, phthalates and paracetamol, in urine samples from nearly 100 Danish men between the ages of 18 and 30. to calculate human exposure to 20 other chemicals. These data were compared with acceptable levels of exposure, which are also derived from the scientific literature. This gave a measure of the potential effect of each chemical, which was then added together using an established method to produce an overall risk measure for the chemical cocktail in each of the men. All men were exposed to unsafe combined exposure and those most exposed to the study had levels 100 times higher than acceptable values, averaging 17 times. “Our assessment reveals worrying excesses of acceptable combined reports,” the researchers concluded. The researchers also managed to rank the chemicals, with BPA being the biggest risk factor, followed by dioxins, paracetamol and phthalates. However, the removal of BPA did not reduce the combined exposure to acceptable levels. Paracetamol has been shown to reduce sperm quality in experimental animals and increase the risk of non-cationic testes in boys born to mothers who used the painkiller during pregnancy. In 2021, a review backed by 90 scientists said: “We recommend that pregnant women be warned in early pregnancy to abandon it. [paracetamol] unless its use is medically indicated and consult a physician or pharmacist if you are unsure. “ The researchers admitted that there were uncertainties in their analysis. For example, the data used were for the years 2009-2010 and, while exposure to BPA has declined slightly since then, exposure to other bisphenols has increased. It is also possible that young women do not have the same chemical exposure as the young men in the study. But the researchers said: “Given the number of chemicals to which humans are exposed, these restrictions almost certainly mean that we have underestimated the risks of the mixture.” The so-called “forever chemicals”, PFAS compounds, can damage sperm, but were excluded from the study as data are limited. Air pollution can also affect sperm quality. In addition to the impact of chemicals, other causes for the decline in sperm quality have been suggested by scientists, with research suggesting links to body weight, lack of physical activity and smoking. “We are not saying that chemicals are the only factor,” Kortenkamp said. “Nutritional epidemiologists say that eating a lot of fatty foods – cheese, butter, cheap fats, a lot of fatty meats – is not good for sperm quality.” Professor Hagai Levine, of the School of Public Health at the Hebrew University in Israel, said: “This is a unique study and adds to the growing evidence of the adverse effects of certain chemicals on human reproduction. “We need to step up our global efforts to study the causes of male reproductive disorders.” Professor Richard Sharpe, of the University of Edinburgh, said: “Contrary to the authors of the new study, and many in the scientific community, I am not convinced that exposure to weakly endocrine-active environmental chemicals plays a significant causal role in the fall. the sperm counts “. He said there was no direct evidence that most of the chemicals evaluated in the study caused damage to human testicular development, although there is good evidence for paracetamol. Sharp said he was convinced that the reduction in sperm count must have an environmental cause, most likely affecting the onset of pregnancy. However, he said that a high-fat, processed diet is harmful in itself and the main source of chemicals, making it difficult to discern who may be to blame. However, Sharpe said it remains possible that certain chemical cocktails could adversely affect sperm count in men.
