Offshore produced water show the potential to inhibit acetylcholine esterase (AChE).
Polycyclic aromatic hydrocarbons and naphthenic acids can potentially inhibit AChE.
Produced water extracts were analysed by effect-directed analysis (EDA).
Butylated hydroxytoluene and 4-phenyl-1,2-dihydronaphthalene were identified by EDA.
Fish caught near offshore platforms showed reduced AChE activity in their muscle.