A cocktail of chemicals found in the body affects sperm quality (study)

A mixture of chemical pollutants measured in human bodies is linked to decreased sperm quality, according to a new study, according to The Guardian.

Scientists say that some chemicals such as bisphenols and dioxins affect hormones and affect the quality of semen, and the study found that these compounds are present together at “amazing” levels, up to 100 times what is considered safe.

Bisphenol A (BPA) is responsible for the highest risks, scientists say. The chemical compound is found in milk and canned food in metal because it comes off the inner lining layer. Important milestones for the healthy development of male sexual function occur during pregnancy, making the results of the study especially relevant for pregnant women, say the researchers.

The number and concentration of sperm has declined alarmingly in Western countries for decades, scientists say, with sperm numbers halving in the last 40 years. Other sexual problems in men, such as malformations of the penis, breast cancer and lowered testicles, have increased in incidence. Hormone-affecting chemicals are the first suspect and the study shows the potential of the chemical cocktail to do harm.

The research team, led by Professor Andreas Kortenkamp of Brunel University in London, said that “we were amazed at the magnitude of the hazard index”, a measure of the risk posed by the chemical cocktail. The team was also surprised that BPA is the most worrying chemical compound, with previous studies focusing on phthalates, which are used in plastics.

Kortenkamp told The Guardian that the research would allow better epidemiological studies of people to analyze the impact. “But I personally believe, with the evidence I have produced, that there is no reason to delay any regulatory action.”

The research, published in the journal Environment International, looked at measurements of nine chemicals, including bisphenol, phthalates and paracetamol, from urine samples from nearly 100 Danish men between the ages of 18 and 30. The study also used existing data, mostly from the European Food Standards Agency, to estimate human exposure to 20 other chemicals.

These data were compared with acceptable exposure levels, also derived from the scientific literature. This provided a measure of the potential impact of each chemical, which was then added together using an established method to produce a general risk measure for each man’s chemical cocktail.

All men were exposed to an unsafe combination of chemicals and the most exposed in the study had levels 100 times higher than acceptable values, averaging 17 times. “Our analysis shows alarming exceedances in the combined acceptable exposures,” the researchers concluded.

Scientists have also been able to classify chemicals, with BPA being the most important risk factor, followed by dioxins, paracetamol and phthalates. However, BPA removal did not decrease the combined exposure to acceptable levels.

Paracetamol has been shown to cause a decrease in sperm quality in laboratory animals and increases the risk of untested testicles in boys born to mothers who use painkillers during pregnancy. In 2021, an analysis by 90 scientists said: “We recommend that pregnant women be warned at the beginning of pregnancy to give up (paracetamol – ed.) If they are not medically recommended and consult a doctor or pharmacist if in doubt ”.

The researchers agreed that there were uncertainties in their analyzes. For example, the data used were from 2009-2010, and while BPA exposure has decreased slightly since then, exposure to other bisphenols has increased. Young women may not have the same chemical exposure as the young men involved in this study.

But researchers said: “Given the multitude of chemicals that people are exposed to, these constraints almost certainly mean that we have underestimated the risks of the mixture.” The so-called “eternal chemicals”, PFAS compounds, could damage semen but were excluded from the study because the data is limited. Air pollution could also affect sperm quality.

In addition to the impact of chemicals, other causes for declining sperm quality have been suggested by scientists, with research suggesting links to body weight, lack of physical activity and smoking.

“We’re not saying only chemicals are the only factor,” Kortenkamp said. “Nutritional epidemiologists say that fatty foods – cheese, butter, cheap fats, a lot of fatty meat – are not good for sperm quality.”

Professor Hagai Levine of the School of Public Health at the Hebrew University of Israel said: “This is a unique study and adds to the growing evidence of the negative impact of some chemicals on human reproduction. We need to increase 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 remain unconvinced that exposure to inactive endocrine chemicals plays an important causal role in reducing sperm count.” He said there was no direct evidence that most of the chemicals in the study harmed the development of human testicles, although there was good evidence of paracetamol.

Sharpe said he was convinced that declining sperm numbers must have an environmental cause, most likely having an impact on early pregnancy. But he said that a fatty, processed diet is both harmful in itself and the main source of chemicals, making it difficult to make a distinction that could be to blame. However, Sharpe says some chemical cocktails may negatively affect sperm counts in men.

Editor: AC

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