On the left is a baby with microcephaly, on the right is a baby with a typical head size
Right now, the Net is overwhelmed with questions over a report that states it’s more likely that the outbreak of microcephaly – a rare neurological disorder that causes newborns to develop abnormally small skulls and brains – is linked to pesticides rather than the spread of Zika virus. The pesticide in question is pyriproxyfen – a larvicide that targets the Zika-spreading Aedes aegypti mosquito, produced by Sumitomo Chemical.
As the hassle about the Zika epidemic runs rampant, independent organizations of doctors from Argentina and Brazil are directly challenging the argument that the Brazilian Zika virus outbreak is the cause of the recent rise in microcephaly birth defect cases.
Following the dramatic increase in congenital malformations, the Brazilian Ministry of Health made a quick move to link the phenomenon to the present Zika virus epidemic. Microcephaly is an inborn condition in which a baby’s head develops abnormally small.
Despite the media hype covering the mosquito-borne Zika virus and microcephaly, there has yet to be proven the scientific connection between the two of them. Only the problem is that proving whether the Zika virus is linked to increased birth defects could take years.
The recent report by the Physicians in the Crop-Sprayed Towns (abbreviated PCST) revealed that the area in which most of the affected persons live had been sprayed with a larvicide deemed to cause birth defects. The PCST’s report revealed that the pesticide, sold under the commercial name SumiLarv, is manufactured by Sumitomo Chemical, a Japanese subsidiary of Monsanto.
Pyriproxyfen is the chemical which was added to the state of Pernambuco’s drinking water-reservoirs by the Brazilian Ministry of Health in 2014, in their great effort to stop the multiplying of the Zika-carrying Aedes Aegyptus mosquito.
This chemical is a growth inhibitor of mosquito larvae, which alters the development process from larva to pupa to adult, thus generating malformations in developing mosquitoes and killing or disabling them. It acts as an insect juvenile hormone or juvenoid, and has the effect of inhibiting the development of adult insect characteristics (for example, wings and mature external genitalia) and reproductive development. It is an endocrine disruptor and is teratogenic (causes birth defects).
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,” according to the report by Physicians in the Crop-Sprayed Towns.
In support of the report by PCST, in the month of January 2016, the Brazilian Association for Collective Health (ABRASCO) published an “open letter” to the Brazils, questioning the linear analysis carried out by the Brazil’s Ministry of Health, which announced the supposed link between the emergent congenital malformations and the Zika virus.
The group brought the public attention to the ignoring of other factors that could have had a direct influence on the problem and worked to minimize the fact that the widespread epidemic in the Pacific and the current epidemic in Colombia, did NOT result in no cases of malformations, much less microcephaly.
The report by PCST states that:
Earlier Zika epidemics did not cause birth defects in newborns, despite infecting gruesome 75% of the population in those countries. Also, in other countries such as Colombia there are no records of microcephaly although there are plenty of Zika cases.
While there has been no shortage of theories regarding the origin of the virus, the World Health Organization (WHO) has been careful not to hastily link microcephaly cases directly to the Zika virus.
“Although a causal link between Zika infection in the pregnancy period and microcephaly has not, and I must emphasize, has not been established, the circumstantial evidence is suggestive and extremely worrisome,” was announced last month by the WHO General Director Margaret Chan.
The group adds that it’s “not a coincidence” that cases of microcephaly have proliferated in Brazil where pyriproxyfen is being used, while in Colombia, Zika infections have not been linked to microcephaly, despite the fact that it has the second highest incidence of the virus after Brazil.
In response to the report, one Brazilian state has suspended use of pyriproxyfen until further notice.
“We decided to suspend the use of the product in drinking water until we have a position from the Ministry of Health, and so, we reinforce further still the appeal to the population to eliminate any possible mosquito breeding site,” Joao Gabbardo dos Reis, state health secretary in Rio Grande do Sul, informed the press.
So what exactly is going on here?
While some say the evidence supporting a link between pyriproxyfen and microcephaly is overwhelming, others are calling it an “ evident conspiracy theory” , and the World Health Organisation (WHO) is insisting that pyriproxyfen is safe in drinking water at the recommended levels.
The reality is that, right now, we have circumstantial evidence suggesting that pyriproxyfen in Brazilian drinking water could be increasing the risk of microcephaly, and this link is made stronger in the absence of a definitive causal link between the neurological disorder and Zika virus. People want answers, so it’s understandable that new evidence or hypotheses are given credence as we try to make sense of what is going on.
While the WHO has explicitly said that the link between the microcephaly and Zika outbreaks has not yet been confirmed , this is less about a lack of scientific evidence and more about giving scientists the time they need to carry out their research properly.
If they’re going to explicitly state that there is a link, they want to be 100 percent sure that this is backed by solid, causal evidence showing how an infection by Zika virus can cause biological changes in a foetus that severely disrupts growth.
The director of Disease Control and Diseases of the Health Department of Pernambuco in Brazil, George Dimech, said to the BBC that the city of Recife currently has the highest reported amount of cases of microcephaly, and yet pyriproxyfen is not used in the region – they use another insecticide altogether. Neurologist Vanessa van der Linden added that, “Clinically, the changes we see in the scans of babies suggest that the injuries were caused by congenital infection and not by larvicide, drug, or vaccine.”
Scientists points out that “humans do not make or use sesquiterpenoid hormones (insect juvenile hormones), which is what pyriproxifen targets”, and over the years, massive research has been carried out on the pesticide’s physiochemical properties, toxicology, and safe levels.
If we take the circumstantial evidence linking microcephaly and pyriproxyfen at face value, it’s a wonder why microcephaly isn’t a much bigger, global problem. The pesticide is approved for use both in the U.S. and Europe, albeit not in the drinking water, as it has been in some regions in Brazil.
There are still a whole lot of questions about why cases of microcephaly appear to have exploded in the recent months and years – many of which will not immediately be answered if scientists do come out and say there is a definitive link between it and Zika virus. But until we have causal evidence for a link between the disease and a certain type of pesticide, it’s unscientific to jump to conclusions based on inconsistent circumstantial evidence.