Chemical Impacts of Ingestion Sample Clauses

Chemical Impacts of Ingestion. Ingested plastics can transfer other pollutants into marine organisms including persistent organic pollutants (POPs) and heavy metals that are either included in the plastics during manufacture or adsorb to them at sea (x.x. Xxxxxx et al. 2009, Xxxxxxx et al. 2013a, Xxxxxxxx et al. 2014). This could be the most serious impact of plastic ingestion at a population level, but there is relatively little information on this issue for birds. There is some evidence that both legacy pollutants such as poly-chlorinated biphenyls (PCBs) and plastic-specific compounds such as polybrominated diphenyl ethers (PBDEs) and at least three phthalates (dimethyl, dibutyl and diethylhexyl phthalate) found in seabirds are derived from ingested plastics (Xxxx et al. 1988, Xxxxxxxx et al. 2014, Xxxxxx et al. 2013, 2015). However, more information is needed on the importance of plastic dose and exposure period on the transfer of these pollutants to birds. The rate at which pollutants xxxxx out of contaminated plastics depends on the plastic polymer and the structure of the toxic compound, with half-lives for different PCB congeners diffusing into water ranging from 10- 10,000 days (Endo et al. 2013). Leaching of toxic compounds is facilitated by oils in the stomach contents, and thus probably occurs more rapidly than these figures suggest. Leaching is expected to be most rapid in species such as petrels that use oils to transfer food to offspring during their protracted foraging trips (Xxxxxx et al. 2015). However, PBDE flame retardants still took several days to reach equilibrium in petrel stomachs (Xxxxxx et al. 2015). As a result, transfer of toxic compounds is likely to be most severe in species that accumulate ingested plastics rather than regurgitating indigestible prey remains. The release of toxic compounds incorporated into plastics during their manufacture is likely to be exacerbated if the plastic items are gradually eroded in the stomach, again suggesting that plastic ‘accumulators’ (cf. Figure 1) are most at risk. Interestingly, ingesting ‘clean’ plastics may offer a mechanism for birds to reduce POP loads. POP sorption-desorption from plastics follow simple diffusion dynamics, and thus plastics which contain few if any toxic compounds (e.g. food packaging) can take up POPs circulating in bird bodies. There are no data on the transfer of POPs to freshwater birds from ingested plastic, but the more transient nature of plastic items in freshwater systems suggests that t...