This is especially troubling given that the manufacturer of Naled, Sumimoto Chemical Corp., is also the manufacturer of the mosquito larvicide SumiLarv, a chemical now believed to have been the real culprit behind the spike in birth defects in Brazil originally attributed to the Zika virus.
"A Possible Link Between Pyriproxyfen and Microcephaly
Dan Evans, Fred Nijhout†
, Raphael Parens∗
, Alfredo J. Morales∗ and Yaneer Bar-Yam∗
∗New England Complex Systems Institute, 210 Broadway Suite 101,
Cambridge MA 02139, †Department of Biology, Duke University, Durham, NC 27708
(Dated: April 13, 2016)
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.
On the question of what pyriproxyfen does, I came across this, "Pyriproxyfen is a potent suppressor of embryogenesis and later development that competes for juvenile hormone receptor binding sites and disrupts the transition from one developmental stage to another –. The mode of action of pyriproxyfen is not fully understood due to the lack of a known signalling pathway and/or a receptor molecule. "
So if this is still the case, people do not fully understand how pyriproxyfen does what it does, which is not that great.
Nature's Games: Will the Global Medical Community Triumph Over Zika Virus?
04 January 2017
"Our data indicate that pyriproxyfen does not affect central nervous system development in zebrafish, suggesting that this larvicide on its own, may not be correlated with the increase in microcephaly cases reported recently."