Actually peanuts are a pretty good source of C20 fatty acids at ~1.38% (even better than canola at only ~0.64% or rice bran at ~0.75% - however, I assume extracting from canola would be cheaper).  But, if you read the responses to this (old) thread you will see that we discussed that:

QuoteRight-- it can be from peanut, but it's often NOT from peanut, and in any case, it's really, really, REALLY highly processed and several steps away even from peanut oil (which, recall.... "should" be safe since it contains such low levels of protein).

No where did anyone say sunscreen producers were manufacturing the chemicals in their products.

ETA:  The reason arachidyl alcohol on an ingredient list raises red flags for those with peanut allergy is because the French word for peanut is arachide.  It is always worth investigating ingredients when a common ingredient can kill you.

Arachidyl Alcohol is not made from peanuts and should not be present in peanuts in an alcohol form.
C20 alcohols are produced from C20 fatty acids or from a synthetic process based on ethylene.

Sunscreen producers are not producing this ingredient (or much of anything else, since their products are blends of chemicals and surfactants) - they are buying it from chemical companies. The chemical companies that make this are using either ethylene (noted above), canola/rapeseed oil or cold water fish oils.

Right-- it can be from peanut, but it's often NOT from peanut, and in any case, it's really, really, REALLY highly processed and several steps away even from peanut oil (which, recall.... "should" be safe since it contains such low levels of protein).

Personally, we DO NOT avoid either arachidyl or arachidonic/arachidic ingredients per se-- only products which seem to be problematic for DD personally. 

For something topical like that, I'd probably try it and see.  No reaction, no reason to avoid.

In the conversation long ago, I think the research I did ended up that arachydil alcohol was made from a plant source which could be peanut.

ok wait. This wikipedia page (no idea how accurate it is) says arachidyl alcohol is made from the reduction of arachidic acid (which is peanut oil and something else).

http://en.wikipedia.org/wiki/Arachidic_acid

So wouldn't that make it bad? Or is there theoretically no protein in peanut oil so there would be even less than none in arachidyl alcohol?

Ok now that I think about it, I think it's arachidic acid that is peanut. They sure sound alike. I think I remember this conversation coming up here in the past.

Hmmm . . . this says it's synthetic.  If it is, then it should be fine. CM??? Dang--I wish we could tag people.

http://www.chemicalland21.com/industrialchem/solalc/ARACHIDYL%20ALCOHOL.htm

ok thanks. I keep seeing it on things meant for kids and wondered but apparently it's nothing to worry about. We'll keep avoiding it. I was hoping that we could use the Cerave sunscreen because it has the active ingredients we like and we can find very little else locally but both varieties have that stuff in it.

We avoid it. I've read it's supposed to be fine. But we have been able to avoid it just fine, so we do.

Is peanut in some form , right?  I'm at Walmart looking at sunscreen and 3 different ones list this in the ingredients, with no "plain English".