Environmental toxic substances, endocrine disruptors and fertility

Over the last few years, there has been growing scientific interest in understanding the relationship between environmental and occupational exposure to toxic substances and contaminants and a variety of human health issues, in addition to the impact that these products may have on a couple’s ability to have children.

Índice

1 Contamination
2 Types of toxic substances
3 Endocrine disruptors

Contamination

A presence in the environment of damaging elements (be they chemical, physical or biological) that are a danger to the living things in that environment is known as environmental contamination.

It would seem that a proportion of cases of sterility with an unknown cause may be generated by or linked to different types of environmental or professional exposure to contaminants in which the individual is subjected to elevated oxidative stress and to damage at a genetic and epigenetic level of his or her reproductive cells [1].

However, their gravity or the adverse impact that these chemical substances have on fertility in couples depends on a number of different factors. For example, the type of product, duration of exposure, concentration of the contaminant and so on.

Types of toxic substances

The best-known toxic agents that potentially affect fertility in human beings are:

Aromatic hydrocarbons (benzenes and toluenes)
Halogenated hydrocarbons (phthalates, propanes and phenyls)
Organochlorine compounds (pesticides)
Certain heavy metals such as lead and cadmium

Endocrine disruptors

In addition, endocrine disruptors are natural or synthetic chemical substances that are exogenous to the organism and affect the production, transportation and activity of the natural hormones in our organism such as oestrogens and androgens. We could say that they behave like “false oestrogens or imitators”. Certain organochlorine pesticides, phthalates, bisphenol A and so on feature in particular.

These disruptors are unlike other environmental toxic substances. That is, the damage is caused depending on the stage during which they are active. In other words, it varies if the exposure is during the foetal stage, during childhood or during adulthood. The size of the dose also has a direct impact.

There are a number of different studies stipulating that, to a greater or lesser degree, we all carry these disruptors in our organisms since many of them are stored in body fat. However, exposure to these chemical substances as adults, or even before birth, could even have a negative impact on the reproductive health of future generations [2].

As such, and depending on when contact occurs, they can be linked to the following conditions:

Abnormalities in urethra formation and closure (hypospadias)
Abnormalities in the position of the testes (cryptorchidism)
Spermatogenesis abnormalities
Cancer of the testes in adults
Ovarian function disorders and benign abnormalities in the uterus and breast
Endometriosis

It is essential that couples with these conditions obtain a detailed environmental medical history. The aim is to prevent, diagnose and treat their fertility issue in terms of its link to these kinds of substances which are now such a common part of our daily lives.

BIBLIOGRAPHY:

Checa Vizcaíno MA, González-Comadran M, Jacquemin B. Outdoor air pollution and human infertility: a systematic review. Fertil Steril. 2016;106(4):897-904.e1.
Brehm E, Flaws JA. Transgenerational Effects of Endocrine-Disrupting Chemicals on Male and Female Reproduction. Endocrinology. 2019;160(6):1421-1435.

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Dr. Jorge Ten, director of the Embryology Unit of Instituto Bernabeu