Microplastics found in Antarctic penguins: chemical reactivity theory to analyze possible toxicity

Micro- and nanoplastics are widespread in the marine environment including polar regions across Antarctica. In Antarctic penguins, eighty percent of microplastics were identified as polyethylene and ten percent as polyester. To analyze the toxicity of these two polymers, oligomers with different numbers of units were used as models. The use of oligomers as polymer models has been used previously with success. We started with the monomer and continued with different oligomers until the chain length was greater than 2 nm. According to the results of quantum chemistry, polyester is a better oxidant than polyethylene, since it is a better electron acceptor. Although there is less polyester than polyethylene in penguins, the presence of polyester may be more harmful than the presence of polyethylene for three reasons: polyester is better electron acceptor and therefore a better oxidant than polyethylene; polyester has negatively charged oxygen atoms and can promote stronger interactions than polyethylene with other molecules; polyester forms stable complexes and can dissociate the guanine-cytosine nucleobase pair. This could affect DNA replication. This theoretical information helps to elucidate the potential damage of micro- and nanoplastics.