Leviticus 11:40 says "If any animal you may eat has died, anyone who carries its carcass...shall wash his clothes." Just don't use Downy fabric softener; according to Wired, (but not online at time of this writing) a main ingredient is Dihydrogenated tallow dimethyl ammonium chloride,
"a derivative of rendered fat from cattle, sheep and horses. Just boil it down and mix with ammonium. After a series of chemical pit stops, it comes out a quaternary ammonium compound, or quat...quats effectively coat your clothing with lipids, (fats) making the fibers soft to the touch."
The Downy website is much more circumspect and leaves out the dead animal part.
mmmm, smells like cheeseburger.
How They Work
Remember your science class in eighth grade? Well, here goes. The most common active ingredients in fabric softeners are based on long-chain molecules, which are positively charged in nature. The molecules usually contain at least one hydrophobic (water-resisting) group, and a positively charged nitrogen atom, which is attracted to the negatively charged fabric surface. The result is a loose ionic bonding and absorption of softener compounds onto the surface of your fabrics.
A few of the vegan sites are on the case, and a few manufacturers like Method and Ecover say that they are plant based and tallow free. Seventh Generation makes theirs from canola oil and is even kosher certified. But not everyone gets it; Website Kosher.com sells Downy, which I suspect wouldn't pass muster in Leviticus.
So if you are vegan and don't like drinking wine made with isinglass, you sure won't like washing your undies in animal fat. And who needs the stuff anyways?
TreeHugger on animal things in our food:
Organic Wine Company Also Does Vegan
Something Fishy about Wine