Geoff, maybe the poisoness chemical you are thinking of is DDT (1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane). Harmless in small doses but in dissolved in body fat so can eventually build up to be very very bad.
DDT was wanned in all countries, since the 1960's. Except Australia which keep using it for much longer.
DEET old name but now commerical name, not sure where the 2nd E comes from. New standard name N,N-diethyl-3-methylbenzamide. Repllent, clear oily liquid, relatively non-toxic.
All is good guys!
