Air and water pollution can affect the sex of a baby born in an area, according to a new US-Swedish scientific study. Some pollutants “favor” boys and others girls.
Places with high levels of PCBs (polychlorinated biphenyls) in the air and water are more likely to give birth to boys than in areas with low levels of such pollutants where a girl is more likely to be born. These chemicals, before their health effects were discovered, were once widely used as refrigerants in electrical appliances and still exist in the environment.
The study shows that areas with high levels of aluminum in the air, usually where the metal is processed, also have higher birth rates for boys than for girls. Something similar, to a lesser extent, occurs where there is increased water pollution from chromium, arsenic and mercury, as well as increased carbon monoxide in the air.
In contrast, when the soil is heavily polluted with lead and iron, which usually occurs in places with heavy industry for years, the birth of girls is favored, the researchers said, led by Andrei Retsky, a professor of medicine at the University of Chicago. data for more than three million births in the US and Sweden and published in the journal PLoS Computational Biology.
The sex of the child is determined at conception and in principle the probability of giving birth to a boy-girl is 50% -50%. However, the analysis of historical demographic trends shows that the boy-girl ratio (usually slightly in favor of the former) is not stable but varies over time and by region. At the biological level it can be influenced by hormonal factors, while various environmental factors can play a role (pollution, climate, etc.), as well as psychological (stress, etc.), which affect pregnant women and consequently in the sex of the baby, although the findings of the studies show a ambiguity.
The new study concluded that climate and seasons, atmospheric temperature, crime, unemployment and more. do not affect the sex of the fetus. On the contrary, environmental pollutants seem to have an effect on one or the other sex of the baby. Living e.g. of the family near a polluting factory can play a role in whether a boy or a girl will be born. A shocking incident (eg a mass murder or a deadly natural disaster with many victims) that causes great mental stress, has been shown to favor the birth of more girls.
Researchers estimate that pollution can affect the boy-girl ratio by up to 3%, which means that in a population of one million people it is possible for 60,000 more boys or girls to be born.
Link to the scientific publication: https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1009586
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