I found the ref on cod liver oil - it was in Neanderthin, not Paleo Diet. On
page 80 of the paperback it says "If you choose to go with fish oil (for
omega 3), please be aware that cod liver oil . . .  contains potentially
toxic quantities of vitamins A and D if the oil is taken in excessive
doses." "Excessive doses" is pretty vague though. If the bottle has the
standard label it must be clear what percent of the RDR of those vitamins
are in each dose! Paleo Diet just had one mention on page 29 about taking an
occasional spoonful of cod liver oil or a vitamin D supplement if you don't
get enough sunshine.

as I was leafing through Paleo Diet I found a ref on Perillo oil, which I
think someone in Japan asked about. The book says "flaxseed oil is best . .
. very low omega 6 to omega 3 ratio or 0.24 . . . Perilla oil . . . has a
healthful omega 6 to omega 3 ratio of 0.27 . . . get it if you can." Based
on the oil table, that would make Perillo oil the second-best oil, since
canola oil has a ratio of 2.00.