Mothproofed Wool Blankets from the 50’s—Are They Safe?

April 1, 2010, by Debra Lynn Dadd

Question from vertemaman

Hello Debra ! I have a few 100% wool blankets from Ayers in Quebec that I inherited a long time ago that date back to the 50's or 60's. The tag says: Moth proof. I really loved these blankets as it is so hard nowadays to get such heavy and warm wool blankets (or if you do, you might have to pay 300$). Do you think they are still toxic, even after 50+ years to have in our home ?

Debra's Answer

I found a link that answers your question: http://knitting.about.com/od/yarn/f/mothproof.htm.

To paraphrase, it says the chemical used to mothproof wool is Mitin FF, which is added to the yarn in the dye bath. It adheres to the yarn in a similar way as the dye does. So, like dye, the chemical will not rub off or wash off in normal cleaning or dry cleaning. Mitin FF is a pesticide that works by killing the moth larvae when they ingest and digest the wool protein. So it doesn't prevent moth larvae from eating your wool 100%, but it does stop them from doing a lot of damage.

Mitin FF has been used as a pesticide in the United States since 1948 and is used exclusively for mothproofing wool. It is considered to be "low to moderately toxic" and to have "low mammalian toxicity."

I would venture to assume that your blankets are mothproofed with Mitin FF. Given that it was not very toxic to begin with, I would say there is little, if any, danger now.