Alternative and legacy flame retardants in marine mammals from three northern ocean regions.

Flame retardants are globally distributed contaminants that have been linked to negative health effects in humans and wildlife. As top predators, marine mammals bioaccumulate flame retardants and other contaminants in their tissues which is one of many human-imposed factors threatening population health. While some flame retardants, such as the polybrominated diphenyl ethers (PBDE), have been banned because of known toxicity and environmental persistence, limited data exist on the presence and distribution of current-use alternative flame retardants in marine mammals from many industrialized and remote regions of the world. Therefore, this study measured 44 legacy and alternative flame retardants in nine marine mammal species from three ocean regions: the Northwest Atlantic, the Arctic, and the Baltic allowing for regional, species, age, body condition, temporal, and tissue comparisons to help understand global patterns. PBDE concentrations were 100-1000 times higher than the alternative brominated flame retardants (altBFRs) and Dechloranes. 2,2',4,5,5'-pentabromobiphenyl (BB-101) and hexabromobenzene (HBBZ) were the predominant altBFRs, while Dechlorane-602 was the predominant Dechlorane. This manuscript also reports only the second detection of hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO) in marine mammals. The NW Atlantic had the highest PBDE concentrations followed by the Baltic and Arctic which reflects greater historical use of PBDEs in North America compared to Europe and greater industrialization of North America and Baltic countries compared to the Arctic. Regional patterns for other compounds were more complicated, and there were significant interactions among species, regions, body condition and age class. Lipid-normalized PBDE concentrations in harbor seal liver and blubber were similar, but HBBZ and many Dechloranes had higher concentrations in liver, indicating factors other than lipid dynamics affect the distribution of these compounds. The health implications of contamination by this mixture of compounds are of concern and require further research.

Chemical and physical changes of microplastics during sterilization by chlorination.

Wastewater treatment plants are known to release microplastics that have been detected in aquatic and terrestrial organisms constituting part of the human diet. Chlorination of wastewater-borne microplastics was hypothesized to induce chemical and physical changes detectable by Raman spectroscopy and differential scanning calorimetry (DSC). In the laboratory, virgin plastics (∼0.05 × 2 × 2 mm) were exposed to differing sterilization conditions representative of dosages used in the disinfection of drinking water, wastewater, and heavily contaminated surfaces. Polypropylene (PP) was most resistant to chlorination, followed by high density polyethylene (HDPE) and polystyrene (PS). Polystyrene showed degradation, indicated by changes in Raman peak widths, at concentration-time regimes (CT values) as low as 75 mg min/L, whereas HDPE and PP remained unaltered even at chlorine doses characteristic of wastewater disinfection (150 mg min/L). However, HDPE and PS were not completely resistant to oxidative attack by chlorination. Under extremely harsh conditions, shifts in Raman peaks and the formation of new bonds were observed. These results show that plastics commonly used in consumer products can be chemically altered, some even under conditions prevailing during wastewater treatment. Changes in polymer properties, observed for HDPE and PP under extreme exposure conditions only, are predicted to alter the risk microplastics pose to aquatic and terrestrial biota, since an increase in carbon-chlorine (C-Cl) bonds is known to increase toxicity, rendering the polymers more hydrophobic and thus more prone to adsorb, accumulate, and transport harmful persistent pollutants to biota in both aquatic and terrestrial environments.