Are Pollution and Poverty Altering the Sex Ratio of Our Babies?

Correlation isn’t causation, but new research reveals clues for scientists to investigate.

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This story was originally published by the Guardian and is reproduced here as part of the Climate Desk collaboration.

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 aluminum 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.

Measures of deprivation, such as a high number of fast food restaurants and vacant buildings, were also linked to statistically significant changes in sex ratios, as were indicators of stress, including road deaths and the Virginia Tech shootings. However, other factors, such as the season of birth, outdoor temperature, rates of violent crime, and unemployment, did not show significant correlations.

The research only demonstrates correlations between the various factors and sex ratios at birth, not cause and effect. Future work to examine the effects of chemicals on human cells or animal models in the laboratory would be needed to show causal links, the researchers said.

“This is a list of suspects to investigate, and all the suspects have some credible evidence, but we’re very far from conviction,” said Andrey Rzhetsky at the University of Chicago, who led the research.

The sex of babies is determined at conception, when exactly half of embryos should be girls and half boys. But hormonal factors can terminate more female embryos, or more male ones, during pregnancy, leading to skewed sex ratios.

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WHO DOESN’T LOVE A POSITIVE STORY—OR TWO?

“Great journalism really does make a difference in this world: it can even save kids.”

That’s what a civil rights lawyer wrote to Julia Lurie, the day after her major investigation into a psychiatric hospital chain that uses foster children as “cash cows” published, letting her know he was using her findings that same day in a hearing to keep a child out of one of the facilities we investigated.

That’s awesome. As is the fact that Julia, who spent a full year reporting this challenging story, promptly heard from a Senate committee that will use her work in their own investigation of Universal Health Services. There’s no doubt her revelations will continue to have a big impact in the months and years to come.

Like another story about Mother Jones’ real-world impact.

This one, a multiyear investigation, published in 2021, exposed conditions in sugar work camps in the Dominican Republic owned by Central Romana—the conglomerate behind brands like C&H and Domino, whose product ends up in our Hershey bars and other sweets. A year ago, the Biden administration banned sugar imports from Central Romana. And just recently, we learned of a previously undisclosed investigation from the Department of Homeland Security, looking into working conditions at Central Romana. How big of a deal is this?

“This could be the first time a corporation would be held criminally liable for forced labor in their own supply chains,” according to a retired special agent we talked to.

Wow.

And it is only because Mother Jones is funded primarily by donations from readers that we can mount ambitious, yearlong—or more—investigations like these two stories that are making waves.

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