A Possible Link Between Pyriproxyfen and Microcephaly.

Area of Science:

• Environmental toxicology
• Developmental toxicology
• Neuroscience

Background:

• The Zika virus was suspected as the primary cause of increased microcephaly in Brazil.
• Evidence linking Zika virus to microcephaly is strong but not conclusive for all cases.
• Geographic disparities in microcephaly incidence raise questions about the Zika virus's sole causality.

Purpose of the Study:

• To investigate pyriproxyfen, an insecticide used in Brazil, as a potential primary cause of microcephaly.
• To explore the molecular mechanisms and toxicological evidence linking pyriproxyfen to microcephaly.

Main Methods:

• Review of scientific literature on pyriproxyfen, juvenile hormone analogs, and microcephaly.
• Analysis of toxicological data from pyriproxyfen manufacturer tests.
• Examination of pyriproxyfen's unprecedented application in Brazilian drinking water.

Main Results:

• Pyriproxyfen, a juvenile hormone analog, shares similarities with molecules like retinoic acid, known to cause microcephaly.
• Other juvenile hormone analogs, like methoprene, have shown developmental toxicity.
• Manufacturer tests indicated potential developmental effects in rat pups, including low brain mass and arhinencephaly.
• Pyriproxyfen's widespread use in Brazilian water supplies is unprecedented.

Conclusions:

• Pyriproxyfen's molecular and toxicological profile suggests a potential causal link to microcephaly.
• The unprecedented scale of pyriproxyfen use in Brazil warrants further investigation.
• A strong recommendation is made to suspend pyriproxyfen use in Brazil pending further research into its role in microcephaly.