Question from E.
Hi Debra, What are your thoughts on flame retardants in natural insulation? I’m trying to fill cracks around a doorway inside my house with a natural type of batting but I’ve noticed all the natural options (sheep’s wool, denim/cotton insulation) are treated with boron/boric acid. I’m confused because I’ve read flame retardants should be avoided at all costs but all these suppliers are stating this is a non-toxic product that you don’t need a dust mask or eye protection for. I thought breathing this stuff in was a no-no – why would I want it in my house? I don’t know what material I can use because it seems everything is treated with flame retardants.
Debra’s Answer
Well, they are incorrect.
For many years boric acid was used on natural fiber mattresses because it was thought to be nontoxic, but there is evidence now that it has health effects of concern.
It is known that boric acid is poisonous if taken internally or inhaled in large quantities. The Thirteenth Edition of the Merck Index says that hat 5 to 20 g/kg has produced death in adult humans. A kilogram (kg) is about 2.2 pounds. So you would have to ingest about 10 to 40 grams of boric acid for it to be fatal. A gram is about one thousandth of a kilogram, so 10 grams would be about .35274 ounces or about 2 teaspoons. So two to eight teaspoons would be fatal, if you opened a container of boric acid and ingested it.
But there is also concern about long term exposure. Repeated day-in and day-out, or in this case night-in and night-out exposure can cause kidney damage and eventually kidney failure.
Long term exposure to boric acid may be of more concern, causing kidney damage and eventually kidney failure.
In Europe, there is a list of chemicals called Registration, Evaluation, Authorisation and restriction of Chemicals Regulations (REACH). As of 2010, the classification of Boric Acid CAS 10043-35-3 / 11113-50-1 is H360FD (May damage fertility. May damage the unborn child.)
Oregon Shepherd offers wool insulation with or without boric acid treatment. You just have to ask. Their solution of boric acid treatment is 8% by volume.
Debra – I’m a little confused as to the potential harmful effects of wool insulation with a boric acid treatment inside your walls. What is the long term “exposure” you are referring to? Is that from inhaling, and can you really inhale this through your walls? Or is the potential harmful long term exposure from skin contact or ingestion?
These are very different things when considering using boric acid within the insulation of your walls vs other applications. And pest problems inside your walls are a real issue too.
I’m trying to make this decision myself right now. There does not seem to be enough good information on boric acid and this usage.
The long-term exposure I was referring to is any exposure where you are actually being exposed to it, such as in a mattress. If the wall is sufficiently sealed so there is no air transfer between the inside of the wall and the air space in the room, it shouldn’t be a problem. However, that said, personally I wouldn’t put it in my walls. I have used wool insulation in the past. I just got batts of untreated wool and stuffed it between the studs. It was wonderful.
I agree there isn’t enough information on boric acid for this usage.
Hi Daniela – Did you end up getting your wool insulation with our without boric acid? Did you notice if the wool treated with boric acid bothered you? Thanks!
Thanks Debra for the thorough & informative answer! I’m so glad I contacted you!! I will try to locate some of this batting you suggested. One thing- is there something I should wrap it in to deter any pests that might find the wool appealing?
COMMENT FROM DEBRA:
Some years ago I insulated my whole kitchen (outside walls) with wool batts from Shepherd’s Dream and had no problems with pests that I know of. I didn’t use a barrier.