Safety of Termite Tenting with Vikane
If you are a homeowner in the US, chances are high you have had to deal with termites. In California, a termite inspection is a stardard part of disclosures when buying a house. Such reports often recommend tenting with Vikane gas to remediate termites. Is that safe, especially for houses resided by very young kids and pregnant women? This article summarizes what I found in my shallow research on this topic for personal reasons. I hope you read this article in full to get a nuanced view of the topic, but if you really want a short summary: there is no solid evidence to confirm or rule out Vikane as a cause of the explosion in childhood chronic diseases, but there are several concerning case reports and observational studies, and there are many steps one can take to protect themselfs from possible safety issues and almost no fumigation company tells their clients about them.
I didn’t want to do this research because it is very hard to prove safety for things that have not been around long: safety issues usually often take decades to show up and regulators almost always are incompetent and captured by vested interests. I just avoided tenting my houses and thought if I really needed one, I will get it done after my kids grow up a bit more and when I go on an weeks long vacation, so that the gas gets weeks to escape. But I had no plan for the following: one morning, earlier this year, I noted people covering my neighbor’s house (adjacent house) and it soon occurred to me that they may be tenting their house. I asked the crew and they confirmed and said that in 45 minutes, they will finish covering the house with a tent and release the gas. 45 minutes is too little to research safety of anything so I just quickly packed up moved with my family to an AirBnB. I also sealed with caulk the loose fitting side door that faced the house being tented. After reaching the AirBnB, I read many published papers on the topic but forgot to summarize the conclusions. Recently, that happened again, with a different but adjacent neighbor so this time, I am writing this document for the next time.
After moving out of my house, I started scouring the published literature to try to find answers to many questions:
what are the adverse health effect of Vikane gas and at what concentration do they show up.
What is the concencentration of Vikane around the tent, e.g. in adjacent houses’ back/front yard.
After tent removal, how long does the gas keep coming out?
Adverse effects of Vikane exposure
Tenting with Vikane has been a common practice in the US for decades so it is almost certain that it does not cause any non-rare obvious significant harms immediately after exposure. But modern medicine is very bad at detecting harms, e.g. chronic disease, that are rare or those that show up months/years after exposure. One could design trials to get solid evidence of causal effects of Vikane even upto 1-2 years after exposure: randomly select half the counties in the US and ban tenting in those counties for 1-2 years and compare the prevalence in chronic diseases in those populations, especially in the young kids. Ideally, when Vikane was introduced, it should have introduced in a randomized manner for at least 4-5 years to get solid evidence of causal harms that show up 4-5 years after exposure. But the health/environment regulatory agencies are usually very very incompetent and sold out to vested interests. Due to that, we know have zillions of suspects for why chronic diseases skyrocketed in the last few decades and all lifestyle changes introduced during the last few decades — including Vikane fumigation — should be treated as a suspect unless there is solid evidence to prove otherwise.
Case Reports
There is a 2015 case report of a 9 year old boy developing brain injury causing involuntary movements after returning to their fumigated Florida home after being cleared to enter by the fumigation company, ~48 hours after fumigation began. A 2019 CDPR paper describes many case reports of adverse health effects suspected to be causes by Vikane: see table 2 in the paper. Notably, in 2016, a California family got symptoms (headache, burning sensation in lungs and throat, chest pain) every time they returned to their home after clearance, even weeks after fumigation. Their 13 month old child who was verbalizing before fumigation, stopped doing so for many months after fumigation. Even 5 weeks after fumigation, the level of slfuryl fluroride, the active ingredient of Vikane was found to be 2.4ppm near their mattress. For reference, a house is required to have the level below 1ppm to be cleared for rentry.
Observational studies
It seems there is only one observational study to assess health issues in fumigation workers. It is a small (n=123) study from Miami. It was conducted in 1998, before modern awareness against p-hacking, so it is not clear whether the entire protocol was decided before the study. It compared congnitive/memory/smell abilities of fumigation workers compared to similar controls and found the former group to be deficient in some tests of those abilities:
Because of the small size of the study and the non-randomized nature and the large number of hypotheses tested, it is not a reliable study. However, despite the millions of dollars of taxpayer funding given to NIH/EPA, it seems nobody has done a followup study to confirm these finds. (Kudos to California Department of Pesticide Regulation for doing some good work (but far from enough) in this area.)
Animal Studies
Animal studies show inhalation exposure at 30ppm leads to elevated levels of fluoride ions in the brain (src):
In the California case report described above, the exposure level was 2.4ppm 5 weeks after clearance for reentry. So the level just on the day of re-entry may have been above 30ppm. In case of bank vaults, after complaints from employees re-entering the facility after clearance, levels of 20ppm have been confirmed (see the 2019 CDPR paper).
In another animal study, a 30ppm exposure for 6 hours/day for 5days/week for 2 weeks lead to lesions (vacuoles) in the brain:
Exposure on Reentry
Even person who has never studied physics/chemistry formally can guess that after the aeration following fumigation, once the residents return home and close windows and stop the fans, the gas levels may rise, sometimes too much in certain pockets of a house. Yet, the PhDs in regulatory agencies only require testing during or just after aeration.
Below is a clipping from the 2019 CDPR paper.
I could no find the full text of 26. It seems the study was conducted by the manufacturer (Dow) and never published openly. And our regulatory agencies didn’t bother forcing them to publish it before granting them regulatory approval. The CDPR toxicology review of sulfuryl fluoride (vol1, vol2) cites several studies by Dow and I could not find the full text of any of them. Some of these studies are crucuially important to determine things like safe duration for re-entry, safety of bystanders.
It is very hard to do studies to assess long-term health impacts, but it is extremely easy to do studies to just measure gas levels on re-entry. Why are there no openly published studies of those levels done people (e.g. EPA/academics) with no obvious COI with the manufacturer? If I missed such a study, please comment and let me know.
Also, the accuracy of the measurement devices have not been independently verified:
Bystander exposure
The research here is in a similar sorry state. There are some papers making computer models of such exposure but they have no value to me. I could only find one study that actually measured levels and it was done by Dow (the manufacturer) and there is no public full text. The CDPR toxicology report has some measurements from it.
The bystander exposure is intially 2x the acceptable clearance level for allowing rentry. This may not be too bad but this is an underestimate: in this study, they fumigated the house with 16oz of gas per 1000ft^3 whereas the maximum allowed dosing is 160oz per 1000ft^3:
If I were the EPA lead
In summary, the safety evidence of Vikane fumigation is dismal and the current regulations fail to do enough to inform/protect residents from preventable harms.
Here are some things the regulatory agencies should do:
Fund high quality studies to assess causal impacts of Vikane fumigation on humans, especially children/infants. One design would be to randomly pick half the US counties and ban fumigation in those counties for a few years and compare the rates of chronic diseases, especially in children, e.g. autism. (This is known as cluster randomization in medical literature.) Termite inspection can be done before and after the trial and people can be compensated for the damage that happened during the trial in the counties where Vikane was banned. A less useful but potentially easlier design could be to randomly select consenting applicants to fumigation jobs and pay them the same money for a few years to not do fumigation and do something where they wont get exposed to fumigation. Then we can compare the difference, but this will not determine what happens to children.
On re-entry, residents should be given access to Miran-like devices to accurate measure instanteneous levels of the gas and sound an alarm at high levels, just like smoke/CO detectors. Immediate neighbors should also be given these devices before the start of fumigation. These devices do not appear to be available on stores like Amazon and appear to be expensive. Private companies can be encouraged to start services to lend these devices. Fumigation companies must be required to disclose the risks even days after re-entry. As mentioned above, the levels of the gas has in some cases be found be elevated above the clearance level even 5 weeks after fumigation, so just asking residents to delay re-entry will miss some preventable cases.
Until further research is done, at least young kids should be kept away from houses under fumigation, especially for a few hours after the tent is removed. For example, they should not play close to a tented house.