Exposure to pollution may have changed the ratio of boys and girls born to millions of parents in the US and Sweden, according to a new study.
The study found that pollution from mercury, chromium and aluminum was associated with the birth of more male babies, while lead pollution increased the number of female babies.
A team at the University of Chicago and the Karolinska Institutet, Stockholm, studied half of the US population (150 million) and the entire Swedish population (9 million), uncovering over 100 possible factors. Like pollution, these factors included parental stress levels, poverty, crime and unemployment in the area - even weather temperatures.
Published in the journal PLOS Computational Biology, the study examined the population of North America for more than eight years and Swedes for over 30 years - so the data is extremely comprehensive.
So how can pollution affect a child's sex? In concept, the sex ratio of babies should be half boys and the other half girls. But scientists are aware that hormonal factors can affect various circumstances during pregnancy - which means that the ratios are naturally biased. However, this new research suggests that air and water pollutants also affect.
Air pollution included iron, lead, mercury, carbon monoxide, aluminum, and polychlorinated biphenyls. Water pollutants included chromium and arsenic. This is the first systematic investigation of multiple chemical pollutants and other environmental factors using large data sets from two continents, the researchers say.
"As disturbing as this news may be, these are still just comparisons, not facts," said Gareth Nye, a professor at Chester Medical School, who reviewed the findings. But it is important to remember, Nye added, that "everything we eat, drink or breathe has the potential to harm our body."
Sources: PLOS Computational Biology, Guardian, Euronews
