Sex ratio of babies linked to pollution and poverty indicators

Study finds some pollutants are correlated with higher levels of boys and others with more girls

A swathe of pollutants and indicators of poverty have been linked to changes in the ratio of baby boys to girls born to millions of parents.

A study of half the US population and the entire Swedish population examined more than 100 possible factors and found, for example, that mercury, chromium and aluminium pollution correlated with more boys being born, while lead pollution increased the proportion of girls. Proximity to farming also affected the sex ratio, possibly due to higher chemical exposures.