A newly released Argentinian report states that the outbreak of Microcephaly, a rare neurological disorder that causes newborns to develop abnormally small skulls and brains, is likely linked to the pesticide pyriproxyfen rather than the spread of the Zika virus.

Pyriproxyfen is a larvicide added to drinking water that is used to target the Zika-spreading mosquito. It is produced by Sumitomo Chemical, a company associated with Monsanto.

“In the area where most sick persons live, a chemical larvicide producing malformations in mosquitoes has been applied for 18 months, and that this poison (pyroproxifen) is applied by the State on drinking water used by the affected population,” states the report, published by Argentinian group Physicians in Crop-Sprayed Towns (PCST) . 

In Brazil where pyriproxyfen is being used, cases of microcephaly have proliferated. Although in Colombia, where the it has the second highest incidence of the Zika virus after Brazil, the infections have not been linked to microcephaly. 

One Brazilian state has suspended use of pyriproxyfen until further notice, based on the findings in the report.

“We decided to suspend the use of the product in drinking water until we have a position from the Ministry of Health, and so, we reinforce further still the appeal to the population to eliminate any possible mosquito breeding site,” Joao Gabbardo dos Reis, State Health Secretary in Rio Grande do Sul.