Organochlorine Pesticides, Polychlorinated Byphenils (PCBs) and Polybrominated Dyphenil Ethers (PBDEs) in Seven Mediterranean Endemic Cetacean Species.

Abstract

Mediterranean Sea is considered as a hotspot for several persistent organic pollutants (POPs), whose potential health end-points include the reproductive, immune and endocrine systems, and are able to cause cancer. Status of most populations of Mediterranean cetacean species is not generally considered to be favorable and chemical pollution is commonly suggested as a probable cause. Long-term biomonitoring of these cetacean populations provide useful information on the POPs-pollution status of western Mediterranean Sea, which might have direct impact in wildlife and human health. We used blubber from 7 different species of cetaceans (n=57) stranded along the Murcia coastline (SE Spain) between 2011 and 2018 to study 16 different organochlorine pesticides (OCPs), 18 polychlorinated biphenyl (PCB) congeners and 8 polybrominated byphenil ethers (PBDE) congeners. DDE and methoxychlor accounted for more than 80% of the ?OCPs in all species. Mean DDE/tDDT ratio was over 0.9 for all the studied species, which indicates the absence of recent exposures to DDT in these individuals. PCB pattern was dominated by PCBs 180, 153 and 138 and was homogeneous between species. On the other hand, PBDE pattern was dominated by BDE 47, although the rest of the composition was highly variable among species. Striped dolphin was the species showing the highest concentrations of most OCPs (tDDT 4752 ± 7415 mg·kg-1 lw.; methoxychlor 2263 ± 2920 mg·kg-1 lw.), ?PCBs (6490 ± 9550 mg·kg-1 lw) and ?PBDEs (73 ± 103 mg·kg-1 lw), generally followed by bottlenose dolphins and common dolphin, which could be explained by their feeding behavior in shallower waters closer to the coast. No significant differences were found among sexes and length was generally not significantly correlated with any compound, although higher concentrations were obvious for older individuals. We lacked enough samples to assess temporal trends. The magnitude of the pollutant concentrations reported in this work was generally lower than those reported for cetacean species in the western Mediterranean. This fact could be explained either by a temporal decrease of these pollutants or different analytical procedures. Although all of these compounds have been banned from decades ago, they are still found at detectable concentrations in cetacean tissues. However, the concentrations found in this study are below those toxicity thresholds reported for marine mammals by different works.