Contamination levels of PCDDs, PCDFs and CoPCbs in fish oils used as raw materials for margarine and shortening and retailed fish

Toxic equivalent (TEQ) levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/DFs) and coplanar polychlorinated biphenyls (CoPCBs) were analyzed in both crude (n = 5) and refined-hardening fish oils (n = 2), which are used in part as the raw materials of margarine and shortening, and in some retailed fish (n = 6), which may be similar to those used as sources of fish oil. PCDDs/DFs-TEQ levels ranged from 0.1 to 13.5 pg TEQ/g fat weight in crude fish oils, from 0.5 to 1.6 pg TEQ/g fat weight in refined-hardening fish oils, and ranged from 1.4 to 31.2 pg TEQ/g fat weight in retailed fish. The ranges of PCDDs/DFs-TEQ in crude fish oils, in refined-hardening fish oils and in retailed fish overlapped each other. In addition, CoPCBs-TEQ levels ranged from 4.9 to 19.6 pg TEQ/g fat weight in crude fish oils, from 0.2 to 1.4 pg TEQ/g fat weight in refined-hardening fish oils, and from 2.7 to 165.8 pg TEQ/g fat weight in retailed fish. TEQ levels of CoPCBs in refined-hardening fish oils were much lower than those in crude fish oils and in retailed fish. This was due to the lower concentrations of less-chlorinated congeners in refined-hardening fish oils, as compared to those in crude fish oils and retailed fish. It appears that less-chlorinated PCBs congeners in refined-hardening fish oils are partly removed during the refining process.