Relevance of current PCB concentrations in edible fish species from the Mediterranean Sea.

Legal restrictions and bans have led to a steady decrease in PCB environmental concentrations. Yet, in recent years PCBs have been found at very high levels in the Mediterranean Sea, for instance, in some apex predators. This work aimed to investigate current PCB (eighteen congeners: #28,52,77,81,101,105,114,118,123,126,138,153,156,157,167,169,180,189) concentrations in the Mediterranean Sea and their relevance today, focusing on their occurrence in edible fish species typically consumed in the Mediterranean diet. In spring 2017, a total of 48 fish samples from the Northern Thyrrenian Sea were collected: 16 specimens of sardine (Sardina pilchardus), 16 of anchovy (Engraulis encrasicolus) and 16 of bogue (Boops boops). PCBs were quantified in the muscle of the animals by means of GC-QqQ-MS. They were found in all samples at the greatest concentrations (ng/g w.w.) in sardine (4.15-17.9, range), and very similar values between anchovy (1.01-7.08) and bogue (1.46-7.22). WHO-TEQ PCB values followed the same order, i.e. sardine (0.410-1.24, range in pg/g w.w.) > anchovy (0.0778-0.396) ~ bogue (0.0726-0.268). These concentrations lied below the European limits of 75 ng/g (w.w.) for the six indicator PCBs and 6.5 pg/g WHO-TEQ for dioxins and dioxin-like PCBs in muscle meat of fish. Additionally, estimated weekly intakes (EWI, in pg WHO-TEQ/Kg/week) for sardine (1.2), anchovy (0.29) and bogue (0.35) scored below the safe value proposed by EFSA of 2 pg WHO-TEQ/Kg/week. When comparing with data reported for the same species in previous Mediterranean studies, values found here were lower than those surveyed in the late 90s and early 2000s; however, they were often not notably different from concentrations reported in last years. This builds up on the concept of a current slow decrease of PCBs in the Mediterranean Sea, likely linked to new inputs and/or remobilization of burdens, and reinforces the need of continous monitoring of these legacy contaminants still ubiquitous today.

Evaluation of PCDD/Fs, dioxin-like PCBs and PBDEs in sperm whales from the Mediterranean Sea.

Numerous studies to date have reported concentrations of Persistent Organic Pollutants (POPs) in different marine mammal species worldwide. Yet data on sperm whales are scarce from rich and unique biodiverse areas such as the Mediterranean Sea. This work aimed to assess levels of dioxin-like polychlorinated biphenyls (dl-PCBs), polybrominated diphenyl ethers (PBDEs), and polychlorodibenzo-p-dioxins and furans (PCDD/Fs) in blubber of sperm whales stranded along the Italian coast between 2008 and 2016. POP mean concentrations (dl-PCBs: 6410 ng/g l.w.; PBDEs: 612 ng/g l.w.; PCDD/Fs: 57.8 pg/g l.w.) were mostly in line with what has been previously reported on the same species in the Mediterranean environment and tended to be higher than those reported from other geographical regions. The relative abundance followed the order dl-PCBs > PBDEs ≫ PCDD/Fs. Interestingly, the non-ortho dl-PCB pattern (126 > 169 > 77) was similar to that described in other studies worldwide and different from what is described in its main prey. This could be linked to particular metabolic activities in sperm whales against these highly toxic contaminants. Total TEQs ranged from 275 to 987 pg/g l.w. and showed the pattern Σnon-ortho-dl-PCBs > Σortho-dl-PCBs > PCDDs > PCDFs, with PCBs' contribution about 96%. These findings highlight the high abundance of PCBs still found in the Mediterranean environment despite having been banned for decades. All sperm whales analyzed in this study surpassed the threshold of 210 pg WHO-TEQ/g l.w. proposed as starting point of immunosuppression in harbour seals; a level of contamination that may have contributed to an impairment of their immune system.