Reduction of organochlorine contaminants from fish oil during refining

Samples of crude fish oil have been refined, and the crude fish oil together with samples taken out after each step of the refining process have been analysed for organochlorine pesticides and PCB (quantified both as CB congeners and total PCB). The levels of organochlorine contaminants in fish oils remain almost constant during the neutralisation and bleaching steps of the refining process. The deodorisation step seems to cause a decrease in the amount of contaminants, especially for the most volatile compounds (alpha-HCH, lindane, HCB) where the levels were reduced to below the detection level. Concentrations of the less volatile organochlorine pesticides (dieldrin, p,p'-DDE and p,p'-DDD) and PCB are reduced to about half the concentration in the crude fish oil.