A retrospective investigation into the occurrence and human exposure to polychlorinated naphthalenes (PCNs), dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs through cod liver products (1972–2017)

Abstract

A retrospective analysis of a number of historical medicinal grade cod liver oil samples produced in Northern Europe revealed relatively high contamination levels of PCNs, PCDD/Fs and PCBs. The total toxic equivalence (TEQ) associated with PCDD/Fs, dl-PCBs and PCNs was in the range 95–427 pg g-1 for Baltic cod liver oils and from 70 to 148 pg g-1 for oils sourced from the North Atlantic. The corresponding range for canned cod liver products (Baltic Sea) sampled in 2017 ranged from 52 to 104 pg g-1 fat (33–34 pg g-1 ww). The contribution from PCBs to the overall TEQ toxicity was around 3–6-fold higher than from PCDD/Fs and ranged from 24 to 318 pg TEQ g-1ww. The estimated summed TEQ intakes of PCDD/Fs, dl-PCBs and dl-PCNs resulting from the consumption of the daily recommended doses was highest for the Baltic cod liver oils ranging from 16 to 293 pg kg-1 body mass (bm) day-1 for an adult, 20–183 pg kg-1 bm day-1 for a teenager and 15–131 pg kg-1 bm day-1 for a child. The contribution to daily adult TEQ intake from PCNs alone, although relatively small is estimated to contribute up to 5-fold above the recent EFSA proposed TWI of 2 pg kg-1 bm. The results indicate that although currently produced fish oils may undergo rigorous purification procedures and show low contaminant levels, cod livers sourced from the Baltic and consumed locally, continue to contribute substantially to the dietary intake of these contaminants.