Health officials in Brazil have been quick to dismiss claims that a larvicide could be responsible for a rise in cases of microcephaly, but their argument is based on a logical fallacy.
Brazil’s Health Ministry said there had been no scientific study that linked the larvicide pyriproxyfen to microcephaly.
The absence of scientific studies on the link between pyriproxyfen to microcephaly does mean there is no link between the larvicide and birth defects. It just means there are no scientific studies, at least I couldn’t find any.
The Brazilian Health Ministry is using the logical fallcy “argument from silence (argumentum ex silentio) – where the conclusion is based on the absence of evidence, rather than the existence of evidence.”
Argentinian doctors suggested pyriproxyfen, which is used to control the Aedes aegypti mosquito, could be associated with the microcephaly.
The organisation, Physicians in the Crop-Sprayed Towns, said the substance had been introduced into drinking water supplies since 2014 in affected areas of Brazil.
“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,” the report said.