It really sucks when a celebrity you like and admire screws up. Before social media, you might never have known whether stars were prone to bouts of excessive credulity when it comes to medicine, conspiracy theories, the paranormal, or whatever. Twenty years ago, for instance, few might ever have known that Jenny McCarthy was into “indigo child woo” or rabidly antivaccine, falling hard for the scientifically discredited concept that vaccines cause autism. That’s just one example.
Of course, some people, celebrity or not, are just prone to conspiracy belief. Unfortunately, sometimes people who have a better track record also screw up. In this case, I’m referring to George Takei, who rose to fame as Hikaru Sulu, helmsman for the U.S.S. Enterprise in the original Star Trek series. He’s someone I’ve always liked and more recently admired for his activism. True fact: I saw him at a Star Trek convention in Cleveland about 26 years ago, where, as part of his talk he off-handedly recommended a restaurant where he had dined the night before the convention. When I met the woman who is now my wife and asked her out on a first date, I took her to that restaurant. So you could say that Takei had a bit of a role in my impressing the woman whom I ended up marrying.
In recent years, Takei has gained prominence as a gay rights activist and icon, as well as a social media juggernaut, with 1.8 million followers on Twitter and 9.5 million Likes on Facebook (including me). He also has a major presence on Tumblr and Instagram.
Yesterday, I was disturbed to see this pop up on my Facebook feed:
Here’s the article: Zika virus not to blame: Doctors cite man-made cause for birth defect epidemic.
Unfortunately, my fears upon reading the title to this article were not unfounded:
The Zika virus has been blamed for thousands of cases of the birth defect microcephaly, a condition in which babies are born with severely shrunken heads and brain damage. But now a medical organization is challenging that connection, saying that the chemical larvicide Pyriproxyfen is instead to blame.
The Argentine organization Doctors in the Crop-Sprayed Towns says that most affected children live in areas in which the chemical was added in 2014 to local drinking water in an attempt to control mosquito populations. The larvicide is used to create malformations in mosquito larvae, in order to impair their development and reproductive abilities. Pyriproxyfen is manufactured by Sumitomo Chemical, a Japanese strategic partner of Monsanto.
“Malformations detected in thousands of children from pregnant women living in areas where the Brazilian state added Pyriproxyfen to drinking water are not a coincidence, even though the Ministry of Health places a direct blame on the Zika virus for this damage,” said the doctors.
Monsanto. It just had to be Monsanto. I will give these cranks props for figuring out a way to blame Monsanto for the microcephaly suspected to be caused by Zika virus without mentioning GMOs. Well played, Second Nexus, well-played. Not so well-played, Mr. Takei. Not so well-played in falling for this.
Unfortunately, it was even worse-played when Mr. Takei responded to criticisms that he was falling for a conspiracy theory:
Is it irresponsible to even raise the question? Here is a link to the report. Surely it warrants further investigation? http://www.reduas.com.ar/…/Informe-Zika-de-Reduas_TRAD.pdf
This is what we in the skeptic biz like to call JAQing off (just asking questions)? As I like to say: Questions are not bad, but when they are built on a premise of pseudoscience they can lead one astray. But what about this report? In this case, what we’re seeing is yet another example of leaping to infer causation from correlation, just as I discussed last week when antivaccinationists noted that in 2014 the Brazilian Ministry of Health also started recommending that pregnant women receive the Tdap vaccine between weeks 27 and 36 of pregnancy. The result has been a whole boatload of antivaccine conspiracies blaming the increase in microcephaly on the Tdap vaccination. One can’t help but wonder what else the Brazilian Ministry of Health did in 2014 that cranks can blame microcephaly on.
Each case is different, though; so let’s take a look at this particular claim. First off, what is Pyriproxyfen? Basically, it’s a pesticide that is effective against a wide variety of arthropoda (which includes insects and spiders). Specifically, it’s a a juvenile hormone analog that prevents insect larvae from developing into adulthood and thus renders them unable to reproduce. It was introduced into the US in 1996 to protect crops against the whitefly.
Now here’s the thing. It’s not as though pyriproxyfen hasn’t been well studied. The WHO even has a web page with its guidelines for pyriproxifen in drinking water. A great deal is known about its physiochemical properties, toxicology, and safe levels. Specifically, the WHO recommends that the dosage of pyriproxyfen in potable water in containers should not exceed 0.01 mg/L under the WHO Pesticides Evaluation Scheme. More specifically:
Pyriproxyfen was not genotoxic in an adequate range of tests for mutagenicity and cytogenicity in vitro and in vivo. JMPR concluded that pyriproxyfen is not genotoxic.
The reproductive toxicity of pyriproxyfen in rats has been investigated in a two- generation study, a study involving treatment of males and females before and in the early stages of gestation (segment 1) and a study of treatment during the prenatal and lactation periods (segment 3). The NOAEL for maternal toxicity was 1000 mg/kg, equivalent to 98 mg/kg of body weight per day, in the two-generation study and 100 mg/kg of body weight per day in the segment 3 study. Reproductive toxicity was observed only in the segment 3 study, in which there was an increased number of stillbirths in the F0 generation and a reduction in the number of implantations and in the mean number of live fetuses in the F1 generation at 500 mg/kg of body weight per day. The NOAEL for reproductive toxicity was 300 mg/kg of body weight per day. No reproductive toxicity was observed in the two-generation study, the NOAEL being 5000 mg/kg, equivalent to 340 mg/kg of body weight per day, the highest dose tested, or in the segment 1 study, the NOAEL being 1000 mg/kg of body weight per day, the highest dose tested.
NOAEL refers to “no-observed-adverse-effect level,” and these are some pretty high levels compared to what is permitted. Indeed, the maximum recommended dosage of 0.01 mg/L is equivalent to less than 1% of the upper limit of the acceptable daily intake.
It goes beyond that, though. In a Quora post, an immunologist named Tirumalai Kamala lays out several other pieces of evidence that make a link between pyriproxyfen and microcephaly highly unlikely. For example:
A larvicide used to kill Aedes aegypti larvae, pyriproxifen is sprayed all the time. Why then did microcephaly arise in a relatively small proportion of children and why did it only start to show up from ~Dec 2015 when pyriproxifen’s been sprayed in Brazil at least through all of 2014 and 2015?
Such widespread use in so many countries begs the question why microcephaly link wouldn’t have shown up in any of those countries in all the years it’s been used there. Of course, dose may well be a factor if much higher doses were used in Brazil. If dose is a determining factor, it still doesn’t explain why microcephaly didn’t show up earlier since usage goes back years, not a few months.
I would also add that Brazil would have to have been using truly massive doses to exceed the acceptable daily intake, not to mention that humans do not make or use sesquiterpenoid hormones (a.k.a. insect juvenile hormones), which is what pyriproxifen targets. Finally, one can’t help but notice that Doctors in the Crop-Sprayed Towns is anything but an objective group. It’s been around at least since 2010, and its message has always been the same dating back to 2010: That pesticides cause spontaneous abortions, infertility, congenital malformations, and a wide variety of disorders. In other words, this is a biased report from a biased group presenting no evidence to back up its conclusions. It’s all speculation based on a fear of pesticides.
Then there’s the fact that the entire conspiracy-laden analysis by this group completely ignores two very important pieces of evidence, that MMWR report of Zika virus in fetuses with microcephaly and the New England Journal of Medicine case report published last week. This report describes the case of a 25 year old previously healthy European woman in Ljubljana, Slovenia who had worked as a volunteer in Natal, the capital of Rio Grande Do Norte state in Brazil since December 2013. She became pregnant near the end of February 2015 and became ill during her estimated 13th week of gestation with a high fever, a rash, musculoskeletal pain, and eye pain. Infection with Zika virus was suspected, but no diagnostic testing was performed. Ultrasound at 14 and 20 weeks showed normal fetal growth and anatomy. The patient ultimately returned to Europe around her 28th week, and a 29 week ultrasound examination showed fetal anomalies. Another ultrasound at 32 weeks showed intrauterine growth retardation, a head circumference less than the second percentile for gestation, along with abnormalities of the brain, including calcifications. The pregnancy was terminated, and the fetus showed prominent microcephaly, with almost complete agyria (lack of the normal folds on the surface of the brain). Other abnormalities included inflammation and evidence of of a viral infection in the neurons.
A detailed family history failed to find any genetic syndromes, and other causes of microcephaly were ruled out. The brain tissue was subjected to next generation sequencing, and:
A complete ZIKV genome sequence (10,808 nucelotides) was recovered from brain tissue. Phylogenetic analysis showed the highest identity (99.7%) with the ZIKV strain isolated from a patient from French Polynesia in 2013 (KJ776791) and ZIKV detected in Sao Paolo, Brazil, in 2015 (KU321639), followed by a strain isolated in Cambodia in 2010 (JN860885, with 98.3% identity) and with a strain from the outbreak in Micronesia in 2007 (EU545988, with 98% identity).
The complete genome sequence of ZIKV that was recovered in this study is consistent with the observation that the present strain in Brazil has emerged from the Asian lineage. The presence of two major amino acid substitutions positioned in nonstructural proteins NS1 and NS4B probably represents an accidental event or indicates a process of eventual adaptation of the virus to a new environment. Further research is needed to better understand the potential implications of these observations.
In other words, the virus isolated from this microcephalic fetus appears to have come from Asia. It also appears to have two mutations in nonstructural proteins, the significance of which are unknown. Again, this is not slam-dunk evidence that Zika virus causes microcephaly, given that it’s only one case. (For instance, something else could have caused the microcephaly and at the same time made the fetal brain more susceptible to infection.) Even so, it adds to the accumulation of evidence linking Zika virus to microcephaly. So the claim of these doctors that it’s not the Zika virus causing microcephaly is looking less and less plausible as more evidence comes in. Has it been proven with slam dunk evidence that Zika virus is causing microcephaly in Brazil? No, but the evidence linking the two appears to be getting stronger.
So, Mr. Takei, let’s talk.
There are lots of conspiracy theories out there. There’s lots of pseudoscience out there. Whenever something like the Zika virus makes it into the news, you can be absolutely sure that conspiracy theories based on pseudoscience will inevitably follow. That’s why it’s so critical to do a little research before sharing something like this. When you have such an enormous social media platform, you owe it to your fans not to use it to spread misinformation like this.