- Toxic chemicals in our food and environment accumulate in the body and act like female hormones.
- Men are much more vulnerable than women to infertility due to pollutants.
- Endocrine-disrupting toxins in women are related to an increase in certain pathologies such as hormone-dependent cancers: breast, ovarian and thyroid, but they do not affect embryonic/foetal ovarian development; a higher level of oestrogen does not alter this process.
Chemical toxins have a “feminising effect” on males, a new study from Spain has found. According to the research, certain chemicals known as endocrine disruptors worsen semen quality and can cause genital malformations in boys before they are born.
On the other hand, it would not affect the gestation of a girl, nor would it affect the quality of the eggs, found the study. In conclusion, Institut Marquès’ study shows that “environmental pollution with toxic chemicals is the main cause of poor semen quality. Now, we have shown that the male is much more exposed than the female to suffer infertility due to the action of polluting substances, as they do not alter the ovarian reserve,” explains Dr Marisa López-Teijón, Director of this international centre for Assisted Reproduction.
What are endocrine disruptors?
Endocrine disruptors are a long list of chemicals created by humans in recent decades. They are commonly used in industry, agriculture and in the home: pesticides, plastics, paints, varnishes, carpets, detergents, dyes, dioxins released from waste incinerators, etc. They are highly resistant to biodegradation.
They are very resistant to biodegradation, which means nature does not know how to metabolise or degrade them. Pollution by persistent organic pollutants is “invisible pollution” that is present in our food and environment.
These substances accumulate in the body and behave like female hormones. An example of their “feminising” effect is the proliferation of fish with genital malformations in rivers that have suffered toxic spills.
What can endocrine disruptors do to males?
One of the consequences of endocrine disruptors is the deterioration of semen quality: According to the WHO, until 1985 the normal number of spermatozoa in the ejaculate was 100 million/cc. This average has decreased over the years to 60 million/cc in 1986, to 20 million/cc in 1992 and to 15 million/cc in 2010.
In previous studies on semen quality in Spain, Institut Marquès has shown that there are large geographical differences in the map of male fertility. After analysing the semen analysis and medical history of 1,239 volunteers aged 18 to 30, the results showed a higher prevalence of oligozoospermia (reduced concentration of sperm in the ejaculate) in Valencia (22.7%), Barcelona (22.7%) and the Basque Country (18.7%). In other words, in the regions of Spain with the highest degree of industrialisation over the last 50 years. And less in Galicia (8.5%) and Andalusia (13.7%), regions with less industry.
Toxic chemical effects on a male foetus
The first contact with these toxic chemicals begins early in life. They reach the foetus from the mother’s blood, through the placenta. The type and amount of toxins that the foetus will receive will depend on the levels that the mother has in her body. During the development of the child’s testicles, at 2-3 months of pregnancy, the action of testosterone, the male hormone, is very important. However, the “false oestrogens” compete with it and do not allow it to perform its function correctly, fewer sperm-producing cells are formed and, in the most severe cases, chromosomal (genetic) alterations occur.
Toxic chemical effects on female foetus impact differently
The goal of the study presented by Institut Marquès at the ESHRE congress is to analyse geographical variations in pollution by oestrogenic disruptors and to assess whether they affect embryonic and foetal development in both sexes in the same way.
The results show that they do not affect the ovarian reserve, as Dr López-Teijón explains: “Women want to have children at an increasingly advanced age, but they are born with a certain number of oocyte precursors (around 300,000) and we wanted to know if this ovarian reserve could be altered in the same way that the quality of their semen is altered in the case of men. Statistically significant differences were found between the results from different geographical areas, but no pattern was found to justify them.”
To carry out their study on the effects of toxins on female fertility, Institut Marquès compared the results of nearly 10,500 women from different autonomous communities “We started from the hypothesis that in the most industrialised areas AMH levels should be lower and that they would correspond to those with the highest prevalence of oligozoospermia in male volunteers, but this was not the case,” said Dr López-Teijón.
What other effects do chemicals have on females?
Although in women endocrine-disrupting toxins are related to an increase in certain pathologies such as hormone-dependent cancers (breast, ovarian and thyroid), they do not affect the development of the embryonic/foetal ovary. The increase in oestrogen levels caused by these substances does not alter this process.