The only reference for the "admission" is a link to http://www.nature.com/news/brazil-asks-whether-zika-acts-alo... which is titled "Brazil asks whether Zika acts alone to cause birth defects".

Nothing in the article justifies the title that it's not the virus.

The article says: "NECSI also suggested, “An alternative cause of microcephaly in Brazil could be the pesticide pyriproxyfen, which is cross-reactive with retinoic acid, which causes microcephaly, and is being used in drinking water.”"

The Wikipedia page for Zika points out at https://en.wikipedia.org/wiki/Zika_fever#Microcephaly_and_ot... : "In February 2016, rumors that microcephaly is caused by the use of the larvicide pyriproxyfen in drinking water were refuted by scientists.[120][121][122] "It's important to state that some localities that do not use pyriproxyfen also had reported cases of microcephaly", read a Brazilian government statement."

It says "12,000 Zika Cases Confirmed in Pregnant Colombian Women — Zero Microcephaly Cases" but http://www.nature.com/news/first-zika-linked-birth-defects-d... says "Researchers have diagnosed one newborn with microcephaly ... All three tested positive for the presence of Zika virus."

I do not trust the quality of this article.