Ubiquitous industrial chemicals and pesticides have a “toxic effect” on germs that play a key role in maintaining human health and could be a threat to male reproductive health, according to two teams of scientists.
“Many chemicals designed to act only on one type of target – say insects or fungi – also affect gut bacteria,” says Britain’s University of Cambridge MRC Toxicology Unit postdoctoral researcher Dr Indra Roux.
Her team’s probe of more than 1,000 potential contaminants found 168 that are likely a danger to the human microbiome.
“Most of these chemicals had not been previously reported to have antibacterial properties,” the researchers say, in a paper published in the journal Nature Microbiology.
“Fungicides and industrial chemicals showed the largest impact, with around 30% exhibiting anti-gut-bacterial activity,” the team says.
“When the microbiome is knocked out of balance, there can be wide-ranging effects on our health, including digestive problems, obesity, and effects on our immune system and mental health,” the researchers warn.
The findings followed the publication on Dec 1 (2025) of a warning by George Mason University researchers in the United States that “insecticide exposure”, particularly to neonicotinoids, could undermine sperm production.
“We concluded it is possible that exposure to these chemicals can lower sperm quality, disrupt hormones and damage testicular tissue,” says study lead author Sumaiya Safia Irfan, whose team’s findings were published by the journal Environmental Research.
While the data used were animal-based, the team found that “the nature of reproductive processes across mammals supports the relevance of these findings to human health”. – dpa
