PARIS — A report says the use of an anti-mosquito pesticide in drinking water could be the cause of the mass outbreak of microcephaly cases in newborns Latin America, and not the Zika virus, as the Brazilian government and the World Health Organization (WHO) have been saying.

French weekly magazine Paris Match cites a report published earlier this month by a team of Argentinean and Brazilian doctors that suggests the malformations appeared at the same time the Brazilian health ministry started using pyroproxyfen, a chemical poison applied to drinking water in the states that have since been hit hardest by microcephaly.

The pesticide is a growth inhibitor of mosquito larvae that generates malformations in developing mosquitoes and causes their death or incapacity. Recommended by the WHO to protect from dengue fever, it is manufactured by Sumimoto Chemical, a Japanese subsidiary of Monsanto. Mosquitoes contaminated by pyroproxyfene spread the poison themselves to other mosquitoes.

With 1.5 million people infected in just a few months, Brazil declared in November that the mosquito-transmitted Zika virus was to blame. But according to the team of researchers, led by Dr. Medardo Avila Vazquez, a neonatal specialist who has previously denounced the affects of chemical products: "malformations detected in thousands of children from pregnant women living in areas where the Brazilian state added pyroproxyfen to drinking water is not a coincidence." The report also notes previous Zika outbreaks did not cause malformations in newborns.

The team instead accuses the government's chemical control strategy of contaminating the environment and the people, as well as failing to fight dengue fever and decrease the mosquito population. "This strategy is in fact a commercial maneuver from the chemical poisons industry, deeply integrated into Latin American ministries of health as well as WHO and PAHO [Pan American Health Organization]," the report says.