Zika Virus, Pyriproxyfen, and Monsanto: What's Causing Brazil's Microcephaly Outbreak?

Dan Wilson

Senior Member.
Zika virus has quickly gained the attention of the world in the past few weeks due to its association with a large outbreak of microcephaly cases in Brazil. However, not everyone thinks the microcephaly outbreak is simply due to Zika virus. Everything from vaccines to GM mosquitoes to man-made pathogens has been accused as the real cause of Brazil's microcephaly.
A new story, however, is gaining a lot of traction on social media and various news sources. A group of doctors from Argentina are proposing that a larvicide, pyriproxifen, is responsible for the outbreak.
Furthermore, they claim that the focus on Zika virus is an intentional cover-up and that a Japanese branch of Monsanto, Sumitomo Chemical, manufactures it (EDIT: Sumitomo is not owned by Monsanto). The report that started this whole story was written by Dr. Medardo Vasquez.
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Malformations detected in thousands of children from pregnant women living in areas where the Brazilian state added pyriproxyfen to drinking water is not a coincidence, even though the Ministry of Health places a direct blame on Zika virus for this damage, while trying to ignore its responsibility and ruling out the hypothesis of direct and cumulative chemical damage caused by years of endocrine and immunological disruption of the affected population.
So what's going on? Is there a cover-up? What's actually causing the microcephaly outbreak? To start off, let's talk about what pyriproxifen is.

What is pyriproxifen and is it toxic to humans?
Pyriproxifen is a larvicide (kills insect larvae) that most people have probably used before. In the U.S., it is marketed as Nylar, an anti-flea product used generally by pet owners. It has been marketed since 1996 and has been subjected to a variety of toxicology tests.

Pyriproxyfen is listed as a Group E carcinogen, as in there was no evidence of carcinogenicity found associated with the compound. In this case, however, we are talking about substances that can cause birth defects (teratogens), which are not necessarily in the same category of carcinogens.
Dr. Vasquez claims that because the larvicide interferes with the normal development of mosquitoes, we should not assume it does not affect human development, as many developmental pathways are conserved between humans and distantly related organisms.

He is right that we should not assume that something that affects insects doesn't affect humans. The problem is that he gives no evidence that pyriproxifen is a teratogen. In fact, all of the available toxicological data would suggest that it is not.
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Developmental or Reproductive Toxicity/ In a 2-generation reproduction study in rats, the systemic NOAEL was 1,000 ppm (87 mg/kg/day). The LOAEL for systemic toxicity was 5,000 ppm (453 mg/kg/day). Effects were based on decreased body weight, weight gain and food consumption in both sexes and both generations, and increased liver weights in both sexes associated with liver and kidney histopathology in males. The reproductive NOAEL was 5,000 ppm. A reproductive LOAEL was not established.
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Developmental or Reproductive Toxicity/ In /a/ developmental study in rabbits, the maternal NOAEL/LOAEL for maternal toxicity were 100 and 300 mg/kg/day based on premature delivery/abortions, soft stools, emaciation, decreased activity and bradypnea. The developmental NOAEL was determined to be 300 mg/kg/day and developmental LOAEL was /not/ ... determined; no dose related anomalies occurred in the four remaining litters studied at 1,000 mg/kg/day.
Although you certainly should not regularly consume pesticides, this one has been determined to not be of significant worry so far. But then again, neither has Zika. Zika virus, as Dr. Vasquez points out, has been around for a long time and has never before been linked to any serious health effects even in the event of large outbreaks. So what is the evidence that Zika or pyriproxifen is responsible for the outbreak?

What's causing the microcephaly outbreak?
The evidence implicating pyriproxifen in the microcephaly outbreak that Dr. Vasquex reports is purely coincidental and also vague. So far the only evidence seems to be that pyriproxyfen (brand name Sumilarv) has started being used within the past 18 months in Brazil in an attempt to control mosquito populations.
No specific regions that received this spraying were mentioned and I have not yet been able to locate any corroborating information on this. That's really all Dr. Vasquez has to offer in his report, there is not much to the link between pyriproxyfen and microcephaly. He seems to be more against the general spraying of chemicals in Brazil altogether, but that is another topic.
The evidence that Zika is causing the outbreak could be described as preliminary. It certainly is a mystery why Zika would suddenly be causing microcephaly when it has a long history of being benign infections. There could very well be another factor involved here, but keep in mind that travel, climate change, and viral mutations could be factors in explaining Zika's sudden spread and emergence of symptoms.
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Why has it exploded so suddenly?

There may have been big outbreaks in Africa and Asia in the past that went undetected; scientists weren't paying much attention. But the current massive epidemic was an event waiting to happen. Latin America has huge numbers of A. aegypti, also known as the yellow fever mosquito, an important vector for Zika. (The Asian tiger mosquito, A. albopictus, which is on the rise around the world, is believed to be a vector as well.) In addition, nobody in the Americas had immunity to the virus. Travel makes it worse. Aedes mosquitoes don't fly more than a few hundred meters during their lives; Zika travels from city to city and country to country when infected people get on cars, buses, trains, and planes.

These combined factors meant that the virus had the ability to spread far and fast once it had arrived.
Do we know for sure that Zika is causing a rise in birth defects?

No. There is strong circumstantial evidence that areas in Brazil hit hard by Zika have experienced a sharp increase in the number of babies born with microcephaly, a condition in which the head is much smaller than normal because the brain fails to develop properly. But it will take at least several months before the results from the first case-control studies of pregnant women infected with Zika are available. Doctors in Brazil first noticed an increase in cases of microcephaly during ultrasounds of pregnant women in June and July, a few months after the sudden rise in Zika infections. Fetal medicine expert Manoel Sarno, who works at the Federal University of Bahia, says the pattern of brain damage he is seeing now looks distinct from microcephaly caused by other infections, such as cytomegalovirus (CMV) or rubella. He and his colleagues started a study in August that is following women infected with Zika during their pregnancy; the results could come out late summer. Similar studies are underway elsewhere in Brazil and in Colombia.
The take home message here is that there is a lot we still don't know about the microcephaly outbreak and Zika virus itself. Implicating pyriproxyfen as the culprit is an extremely premature assumption that has the attraction of blaming Monsanto for more things.
There is currently no evidence that supports the idea that pyriproxyfen is responsible for Brazil's recent reported birth defects. When new outbreaks and public health problems appear, it is important to not let fear-mongering influence decision-making and not be swayed by an explanation that is better described as a guess. More information on this topic will help to clear up the situation, but until then it's better to not simply default to blaming corporations and chemicals.
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also to bear in mind, Dr Vasquex in his report you linked says
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3. Previous Zika epidemics did not cause birth defects in newborns,despite infecting 75% of the population in those countries. Also, in othercountries such as Colombia there are no records of microcephaly; however,there are plenty of Zika cases


But what i've found so far is:
Yap, the country with 75% infected and no known birth defects, is only a population of 12,000 and the outbreak studied occured in 2007. As you have stated earlier viruses can and do mutate.
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No such problems were seen in the first carefully studied Zika outbreak, which was on Yap Island in Micronesia in 2007. But Yap has fewer than 12,000 residents. The current outbreak is the first in which scientists have seen the virus invade a large continent where no one is immune


And, if this reporting is accurate, it seems Columbia wouldn't know yet. (bold mine)

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No doubting that Zika is moving north. The outbreak of the creeping paralysis in Colombia started in October but it won't be until June that it will be known if there will be an increase in babies born with microcephaly. In Cucuta and the surrounding area, there are 27 cases of paralysis and 27,000 cases of Zika across the whole of Colombia.

Yap, the country with 75% infected and no known birth defects, is only a population of 12,000 and the outbreak studied occured in 2007.

The population size infected could certainly matter. In some past examples of outbreaks of devastating diseases, only a small fraction of the total infected population developed symptoms or died. Polio is probably the most well-known. Though it was devastating, most people that got infected did not become paralyzed. This could very well be the case with Zika, but so much just remains to be seen.
Furthermore, they claim that the focus on Zika virus is an intentional cover-up because a Japanese branch of Monsanto, Sumimoto Chemical, manufactures it.

In your write up, you state that Sumimoto is a branch of Monsanto - do you have a source for that information?
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In your write up, you state that Sumimoto is a branch of Monsanto - do you have a source for that information?

Dan doesn't actually state that, it says those who are making the claim re: Zika caused by pyriproxyfen say that Sumimoto is a branch is Monsanto. That comes from the link in the OP, dot point 3 on page one:

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3. The pyroproxyfen being used (as recommended by WHO) is manufactured by Sumimoto Chemical, a Japanese subsidiary of Monsanto.

Edit: of course they haven't provided a source for making that connection, and I would doubt that it's true. All I can find is that the two companies have worked together in the past, but are not subsidiary's of each other.
Dan doesn't actually state that, it says those who are making the claim re: Zika caused by pyriproxyfen say that Sumimoto is a branch is Monsanto. That comes from the link in the OP, dot point 3 on page one:

Excellent - thanks for clearing that up.
In your write up, you state that Sumimoto is a branch of Monsanto - do you have a source for that information?
i found this PDF from Sumimoto. Doesnt sound like a subsidiary, but says there is a collaboration. This is for weeds, Dec 2014.
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Sumitomo Chemical has reached a long-term agreement for weed management collaboration in Brazil and Argentina with Monsanto Co. as an expansion of its ongoing strategic partnership with the leading U.S. seed and biotechnology company http://www.sumitomo-chem.co.jp/english/newsreleases/docs/20141209e.pdf
Monsanto addressing this theory directly on their blog

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You may have seen misinformation and rumors on social media regarding Monsanto, the Zika virus and microcephaly. Unfortunately, this misinformation causes unwarranted fear and distracts from the health crisis at hand and how you can take steps to protect you and your family. Here are some facts:

  • Neither Monsanto nor our products have any connection to the Zika virus or microcephaly.
  • Monsanto does not manufacture or sell Pyriproxyfen.
  • Monsanto does not own Sumitomo Chemical Company. However, Sumitomo Chemical Company is one of our business partners in the area of crop protection.
  • Glyphosate is not connected in any way to the Zika virus or microcephaly.
  • GMOs have no role in the Zika virus or microcephaly.
The Zika virus is a tragic and critical health issue. Dealing effectively with such an important health threat requires a focus on the facts. As a science-based company working to help meet some of the world’s biggest challenges we support all efforts to combat this health crisis. We hope all efforts will be taken based on the facts, not rumors.

Emphasis is my own

Monsanto addressing this theory directly on their blog

Thank you, I had searched briefly for any confirmation on whether or not Sumitomo Chemical is actually owned by Monsanto but couldn't be sure at the time so I didn't follow up on it. It seems like Dr. Vasquez simply made up the idea of Monsanto being involved.. Goes to show how fast some people will believe stories like this I suppose.
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bold mine
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Scientists debunk theory linking pesticide, not Zika, to birth defects
Feb 16, 2016
Brazil's Ministry of Health rejected any link between the chemical and the microcephaly outbreak, noting the World Health Organization deems pyriproxyfen safe for use as a pesticide.

"There's a lot of alarmism going around right now, and we would all benefit if it would get tamped down a bit," said Grayson Brown, director of the public health entomology laboratory at the University of Kentucky in Lexington.


The Argentine environmental group said on its website that cases of microcephaly have occurred only in places in Brazil where the pesticide has been used. But the Brazilian Ministry of Health said cases have increased across the board — even where the pesticide hasn't been sprayed. http://www.wfaa.com/news/nation-now/scientists-debunk-latest-zika-claims/44833101

and from CNN
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The Brazilian Health Ministry says that "there is no epidemiological studies showing the association between the use of Pyriproxyfen and microcephaly."

In a statement, the ministry also says that "unlike the relationship between the Zika virus and microcephaly, which has had its confirmation attested in tests that indicated the presence of the virus in samples of blood, tissue and amniotic fluid, the association between the use of Pyriproxyfen and microcephaly has no scientific basis.

"Importantly, some localities that do not use Pyriproxyfen were also reported cases of microcephaly." http://www.cnn.com/2016/02/17/health/brazil-who-pesticide-microcephaly-zika/
In an important update on the Zika virus, a little more evidence has come to light strengthening the link between microcephaly and the virus.
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Pregnancy outcomes among the nine confirmed cases included two early pregnancy losses, two elective terminations, and three live births (two apparently healthy infants and one infant with severe microcephaly); two pregnancies (approximately 18 weeks’ and 34 weeks’ gestation) are continuing without known complications. Confirmed cases of Zika virus infection were reported among women who had traveled to one or more of the following nine areas with ongoing local transmission of Zika virus: American Samoa, Brazil, El Salvador, Guatemala, Haiti, Honduras, Mexico, Puerto Rico, and Samoa. This report summarizes findings from the nine women with confirmed Zika virus infection during pregnancy, including case reports for four women with various clinical outcomes.
We still don't have a confirmed causative link but the available evidence supports the idea for now. This evidence in these case reports also further reject the idea that pyriproxyfen is responsible for anything.