A Possible Link between Pyriproxyfen and Microcephaly

6 Pages Posted: 5 Jul 2017

See all articles by Dan Evans

Dan Evans

New England Complex Systems Institute

Fred Nijhout

Duke University

Raphael Parens

New England Complex Systems Institute

Alfredo Morales

New England Complex Systems Institute

Yaneer Bar-Yam

New England Complex Systems Institute

Date Written: April 13, 2016

Abstract

The Zika virus is the primary suspect in the large increase in microcephaly cases in 2015-6 in Brazil, however its role is unconfirmed despite individual cases of viral infections found in neural tissue. Here we consider the alternative that the insecticide pyriproxyfen, used in Brazilian drinking water for mosquito control, may actually be the cause. Pyriproxifen is an analog of juvenile hormone, which corresponds in mammals to regulatory molecules including retinoic acid, a vitamin A metabolite, with which it has cross-reactivity and whose application during development causes microcephaly. Methoprene, another juvenile hormone analog approved as an insecticide has metabolites that bind to the retinoid X receptor, and causes developmental disorders in mammals. Isotretinoin is another example of a retinoid causing microcephaly in human babies via activation of the retinoid X receptor. Moreover, tests of pyriproxyfen by the manufacturer, Sumitomo, widely quoted as giving no evidence for developmental toxicity, actually found some evidence for such an effect, including low brain mass and arhinencephaly — incomplete formation of the anterior cerebral hemispheres — in rat pups. Finally, the pyriproxyfen use in Brazil is unprecedented — it has never before been applied to a water supply on such a scale. Claims that it is not being used in Recife, the epicenter of microcephaly cases, do not distinguish the metropolitan area of Recife, where it is widely used, and the municipality, where it is not. Given this combination of information we strongly recommend that the use of pyriproxyfen in Brazil be suspended pending further investigation.

Keywords: Zika, Microcephaly, Pyriproxyfen

Suggested Citation

Evans, Dan and Nijhout, Fred and Parens, Raphael and Morales, Alfredo and Bar-Yam, Yaneer, A Possible Link between Pyriproxyfen and Microcephaly (April 13, 2016). Available at SSRN: https://ssrn.com/abstract=2764352 or http://dx.doi.org/10.2139/ssrn.2764352

Dan Evans

New England Complex Systems Institute ( email )

24 Mt. Auburn St.
Cambridge, MA 02138
United States

Fred Nijhout

Duke University ( email )

100 Fuqua Drive
Durham, NC 27708-0204
United States

Raphael Parens

New England Complex Systems Institute ( email )

24 Mt. Auburn St.
Cambridge, MA 02138
United States

Alfredo Morales

New England Complex Systems Institute ( email )

24 Mt. Auburn St.
Cambridge, MA 02138
United States

Yaneer Bar-Yam (Contact Author)

New England Complex Systems Institute ( email )

210 Broadway
Suite 101
Cambridge, MA 02139
United States
617-547-4100 (Phone)

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