New research shows concentrations of the most used weed-killing chemical across the globe, Roundup, do not accumulate in human breast milk.

The recent study is the first of its kind to have its results independently verified by an accredited, outside organization, Washington State University reported. The U.S. Environmental Protection Agency (EPA) is now incorporating the study into an ongoing review of glyphosate regulations spurred by a report released by the Moms Across America advocacy group last year.

"The Moms Across America study flat out got it wrong," said Michelle McGuire, an associate professor in the WSU School of Biological Sciences. "Our study provides strong evidence that glyphosate is not in human milk. The MAA findings are unverified, not consistent with published safety data and are based off an assay designed to test for glyphosate in water, not breast milk."

The Moms Across America and Sustainable Pulse study claimed that traces of glyphosate were found in three in 10 breast milk samples looked at in the study. These potentially false results could discourage mothers from breast feeding, which has "unparalleled" nutritional and immunological benefits for both mother and child.

To make the recent findings disputing this study, the researchers collected milk and urine samples from 41 lactating women in the areas of Moscow, Idaho, and Pullman, Wash., which all contain agricultural land known to use this popular weedkiller.

The biological samples were analyzed using glyphosate and glyphosate metabolites using high sensitivity liquid chromatography-mass spectrometry. These methods did not find any traces of glyphosate or glyphosate metabolites in any of the breast milk, even if there were detectable levels in the same individual's urine.

"In conclusion, our data-obtained using sophisticated and validated methods of analyses- strongly suggest that glyphosate does not bioaccumulate and is not present in human milk even when the mother has detectable glyphosate in her urine," McGuire said. "These findings emphasize the critical importance of carefully validating laboratory methods to the biological matrix of interest, especially when it is as complex as human milk."

The findings were presented at the Federation of American Societies for Experimental Biology Conference.