Question from Arash
Hi Debra,
I’ve used your site as a great resource over the past few months and my first go-to. I thank you for all you do.
I couldn’t find an answer to this and if you have any info maybe others would find it helpful too.
I’ve found out that the previous owners of our new house had permethrin sprayed on all the floorboards, top side and bottom, and the stairs too.
This was done over 20 years ago, but I don’t know how much of it will have soaked right into the wood and maybe (on the upper floors) into the drywall of the floor below.
Having failed to find much info on whether it offgasses and to what extent, I decided to just assume it does still off gas.
Also, apparently the dust under the floorboards will have soaked up a lot of permethrin, so dust coming through ceiling light fittings and up through floorboards is definitely a problem even if off gassing is not.
I was just wondering if you had any advice on how best to address this.
I’m thinking maybe HDPE or LDPE sheeting all over the floorboards and taped around the perimeter of each room to seal it all in. Then new flooring on top. Marmoleum or solid wood would be healthiest but they can’t be floated so would have to be nailed into the floorboards thereby breaking the plastic seal. Or glued to plywood which has formaldehyde issues.
Also unsure how to address the dust/vapor movement through the ceiling light fittings… maybe fire proof lighting as that creates a bit more of a barrier but not a complete one.
Not to mention the stairs, I don’t know how practical it would be to seal them all in with LPDE / HDPE. And the under-stairs storage which houses the gas/elec meters etc can’t really be sealed using plastic so don’t know what to do there.
Any and all advice would be very gratefully received.
Thanks Debra.
Debra’s Answer
First, Marmoleum IS available floating and so are hardood floors so that IS an option if you want it.
And second, your Permethrin exposure is not particularly a problem.
Permethrin is widely used on clothing for protection from ticks. “Exposure risk of permethrin-treated clothing to toddlers is 27 times below the EPA’s Level of Concern (LOC).” Permethrin Fact Sheet.
Not only is Permethrin not particularly toxic, you have time on your side. Here is a great article about what happens to pesticides over time: NATIONAL PESTICIDE INFORMATION CENTER: Pesticide Half-life.
About Permethrin it specifically says:
Each pesticide can have many half-lives depending on conditions in the environment. For example, permethrin breaks down at different speeds in soil, in water, on plants, and in homes.
- In soil, the half-life of permethrin is about 40 days, ranging from 11-113 days.
- In the water column, the half-life of permethrin is 19-27 hours. If it sticks to sediment, it can last over a year.
- On plant surfaces, the half-life of permethrin ranges from 1-3 weeks, depending on the plant species.
- Indoors, the half-life of permethrin can be highly variable. It is expected to be over, or well over, 20 days.
Well over 20 days. You’ve had 20 years. It’s highly doubtful there would be any Permethrin left in your home at this time.
I’m confused. Permethrin in my opinion is very toxic. It damages the nervous system of the insect in order to kill it. It also damages our nervous systems. My friend used a permethrin product in her home and by the next day was violently ill. She developed MCS and one of her daughters was sickened as well. My neighbors spray this on the lawn in Florida and it has chemically injured people. After TrueGreen sprayed a homeowner’s lawn (within 15 ft. of her), she suddenly took ill with respiratory, vomiting, and nervous system Issues. It even sickened her dog. She was a medical professional in Bradenton, Fl., and has since gone on to warn people about pesticides and their dangers. I run from this chemical. It can and does cause nervous system damage in susceptible persons.
One of the difficulties of the entire field of toxics is determining the toxicity of a material.
There is the inherent toxicity of a material which is determmined by toxicological tests, and then there is the individual toleraance.
I based my statement on the information in the Pyrethrin Fact Sheet I linked to. I can’t consider individual tolerance because it’s different for each person.
You said, “It can and does cause nervous system damage in susceptible persons.” Yes. In susceptible persons.
This is part of the difficulty in establishing toxicity of any chemical and having chemicals banned. Even when animal studies are being done, a chemical is only considered toxic if a percentage of animals show a response. And the other are unaffected.
You and your friend are two of the more susceptible.
Because of this I can’t say any material is safe for everyone. But there are chemicals known to be harmful to many and those are the ones I find alternatives for.
Great news re the permethrin! Thanks so much for that. Was struggling to find that info.
I think the type of marmoleum flooring that can be floated is their “click” range, which uses formaldehyde in the base. Or is there something I’m missing? I thought it was just their sheet products that are free of formaldehyde.
It’s my understanding there is no formaldehyde in the click base of Marmoleum. I actually just looked at it recently.