You have probably seen the same stories I have that point the finger for the birth defects attributed to the Zika virus instead to a larvicide sprayed in parts of Brazil to get rid of mosquitos. The larvicide has been sprayed--about that there is no doubt. And it is produced by Sumitomo, which has a connection to Monsanto, although Monsanto itself says that Sumitomo is just a "business partner" and that Monsanto does not manufacture this larvicide. The still unanswered question, though, is whether or not this larvicide is the problem. The accusation was actually brought to the world's attention by an Argentinian group.
According to the Physicians in Crop-Sprayed Towns (PCST), a chemical larvicide that produces malformations in mosquitoes was injected into Brazil's water supplies in 2014 in order to stop the development of mosquito larvae in drinking water tanks. The chemical, which is known as Pyriproxyfen, was used in a massive government-run program tasked to control the mosquito population in the country.
"Malformations detected in thousands of children from pregnant women living in areas where the Brazilian state added pyriproxyfen to drinking water is not a coincidence," the PCST wrote [pdf] in the report. For instance, the Brazilian Health Ministry had injected pyriproxyfen to reservoirs in the state of Pernambuco. In the area, the proliferation of the Aedes aegypti mosquito, which carries the Zika virus, is very high, the PCST said. Pernambuco is also the first state in Brazil to notice the problem. The state contains 35 percent of the total microcephaly cases in the country.
The group of Argentine doctors points out that during past Zika epidemics, there have not been any cases of microcephaly linked with the virus. In fact, about 75 percent of the population in countries where Zika broke out had been infected by the mosquito-borne virus. In countries such as Colombia where there are plenty of Zika cases, there are no records of microcephaly linked to Zika, the group said.The Brazilian government responded today by denying these allegations.
“Unlike the relationship between the Zika virus and microcephaly, which has had its confirmation shown in tests that indicated the presence of the virus in samples of blood, tissue and amniotic fluid, the association between the use of pyriproxyfen and microcephaly has no scientific basis,” the statement said.
“It’s important to state that some localities that do not use pyriproxyfen also had reported cases of microcephaly.”
The government said it only used larvicides recommended by the World Health Organisation (WHO).The reality is that at the moment no one really knows for sure what the exact connection is between the zika virus and birth defects. Correlation is not necessarily causation, and thus far it is not clear how strong the alleged correlations are between the zika virus and birth defect and/or between this larvicide and the birth defects. So, using the abundance of caution principle, it still seems reasonable for women in mosquito-prone areas to use extreme caution with respect to getting pregnant, and that spraying to get rid of mosquitos continue unabated--albeit with something other than a larvicide that is suspected of causing problems.