The Brazilian state of Rio Grande do Sul suspended the use of the larvicide Pyriproxyfen, used to treat water to combat the spread of the mosquito carrying the Zika virus, the regional government said Sunday.

In a communique, the state government said that "the suspension was communicated to the 19 Regional Health Coordinating Authorities, which in turn will inform the respective Municipal Monitoring services" in all cities in the state.

The measure was taken after doctors with the Argentina-based Physicians in the Crop-Sprayed Towns organization and the Brazilian Collective Health Association, or Abrasco, questioned whether the larvicide might be linked with microcephaly.

To date, Brazilian scientists had associated the increase in microcephaly cases with Zika, which - like dengue and Chikungunya - is transmitted by the Aedes aegypti mosquito.

But on Sunday, Rio Grande do Sul Health Secretary Joao Gabbardo said that, despite the fact that a relationship between the larvicide and microcephaly has not been proven, the "suspicion" that there may be a linkage had led the organizations to decide to "suspend" the use of the chemical.

"We cannot run that risk," Gabbardo said.

In response, Health Minister Marcelo Castro said that the larvicide supplied by his ministry presents no danger to the public.

"That is a rumor lacking logic and sense. It has no basis. (The larvicide) is approved by (the National Sanitary Monitoring Agency) and is used worldwide. Pyriproxyfen is recognized by all regulatory agencies in the whole world," Castro told reporters in the northeastern city of Salvador.

In a statement, Sumitomo Chemical, the manufacturer of the larvicide, said that "there is no scientific basis for such a claim," adding that the product has been approved by the World Health Organization since 2004 and the U.S. Environmental Protection Agency since 2001. EFE