U-M study: Exposure to common herbicides linked to premature births

Chemicals found in widely used herbicides like Roundup may cause preterm births

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A new study from the University of Michigan has found a connection between exposure to widely used herbicides and premature births.

The University of Michigan conducted a nested case-control study among a cohort of pregnant women in northern Puerto Rico that examined the connection between exposure to a chemical found in herbicides and preterm births as part of ongoing research of contamination threats. The study, published Wednesday, found that women in the later months of their pregnancy had an increased risk for premature birth if exposed to the chemical glyphosate, which is found in weed killer Roundup and other herbicides.

Researchers tested urine samples of the pregnant women within the cohort for levels of glyphosate and a “highly persistent” environmental degradate of glyphosate called aminomethylphosphonic acid (AMPA), officials said. The study found that “samples collected near the 26th week of pregnancy were associated with increased odds” of preterm births, while the connection between the chemicals and premature births was “inconsistent or null” for women in the earlier stages of their pregnancies.

Preterm births occur when a baby is born before 37 weeks, as opposed to a full-term delivery that typically occurs at 40 weeks. A premature birth creates an increased risk for adverse long-term health effects for the child.

Researchers say glyphosate may induce oxidative stress within living organisms, which has been reported in other studies as a factor in premature births.

“Since most people are exposed to some level of glyphosate and may not even know it, if our results reflect true associations, then the public health implications could be enormous,” said study author John Meeker, professor of environmental health sciences and senior associate dean for research at the U-M School of Public Health.

According to officials, glyphosate is the most heavily used herbicide across the globe, and there is “mounting evidence of its negative effects on human health,” a press release reads Wednesday. Because of the chemical’s widespread use, and AMPA’s “persistence in the environment,” the researchers say further investigation is necessary to determine just how significantly the chemicals may affect human reproduction and development.

“Despite the potential for widespread exposure to glyphosate and AMPA, there is very little information regarding the health effects of exposure during pregnancy,” said study author Monica Silver Wednesday. “Ours is the first study to measure AMPA, and only the second to measure glyphosate in relation to birth outcomes.”

The study reports that only one other study is known to have examined the connection between urinary glyphosate levels in pregnant women and the length of gestation. That study, carried out in rural Indiana, did also find that levels of the chemical found in pregnant women significantly correlated with shortened gestational length, researchers said.

“Our results are consistent with those findings when explored in a different study population and using a different study design, which lends some additional confidence to what we’re observing, but more work is needed,” Meeker said.

The U-M scientists hope to expand their research to other cohorts in the United States.

Click here to read the entire U-M study.


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