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Men who are exposed to common insecticides have a lower sperm concentration: at least this is the correlation found by researchers in a review. The results were published in mid-November in the journal Environmental Health Perspectives.

"Understanding how insecticides affect sperm concentration in humans is critical, as they are ubiquitous in the environment and have been shown to endanger reproduction," said lead author Lauren Ellis of Northeastern University, according to a statement. "Insecticides are a public health problem and a problem for all men, who are exposed to them, especially through the consumption of contaminated food and water," says Ellis.

For the study, the scientists examined 25 studies on occupational and environmental insecticide exposure conducted over a period of almost 50 years. In total, data from around 1700 men were taken into account. In the study, the researchers focused in particular on the insecticide classes of so-called organophosphates and N-methylcarbamates. "They're made to kill things, and they're biologically active by nature," Melissa J. Perry of George Mason University, lead author of the study, told the Guardian.

The result of the study: Higher exposure to certain insecticides is associated with lower sperm production in adults.

"The chemicals seem to interfere with the production of the human endocrine system, which has a direct impact on how much and how normal sperm is produced," Perry told the Guardian. Agricultural workers were most exposed, but about one-third of the study participants were exposed to them primarily through food or other environmental factors.

"The recommendation we're making is to recognize that exposure to insecticides is a public health concern," Perry said. "And we really need to look for policy solutions that recognize that there is a health threat." While additional studies could be beneficial, the "strength of the evidence" would already justify reducing exposure to the substances. In this way, further damage to male reproduction could be prevented.

In the past, studies have repeatedly shown that the average sperm concentration has dropped significantly since the 1970s. Smoking or certain medications are also suspected of contributing to this. You can read more about this here.