Dr. Andres Carrasco, an Argentine neuroscientist who challenged pesticide regulators to re-examine one of the world's most widely used weed killers, has died. He was 67. Dr. Carrasco, a molecular biologist at the University of Buenos Aires and past-president of Argentina's CONICET science council, was a widely published expert in embryonic development. His 2010 study on glyphosate [became] a major public relations challenge for the ... Monsanto Company. Glyphosate is the key ingredient in Monsanto's Roundup brand of pesticides, which have combined with genetically modified Roundup-Ready" plants to dramatically increase the spread of industrial agriculture around the world. [The technology's] spread has increasingly exposed people to glyphosate and other chemicals. Dr. Carrasco, principal investigator at his university's Cellular Biology and Neuroscience Institute, told The Associated Press in a 2013 interview that he had heard reports of increasing birth defects in farming communities after genetically modified crops were approved for use in Argentina, and so decided to test the impact of glyphosate on frog and chicken embryos in his laboratory. His team's study, published in the peer-reviewed Chemical Research in Toxicology journal, found that injecting very low doses of glyphosate into embryos can change levels of retinoic acid, causing the same sort of spinal defects that doctors are increasingly registering in communities where farm chemicals are ubiquitous. "If it's possible to reproduce this in a laboratory, surely what is happening in the field is much worse," Dr. Carrasco told the AP.