Chemical and toxicological assessment of leachates from UV-degraded plastic materials using in-vitro bioassays

The broad use of plastics and the persistence of the material results in plastic residues being found practically everywhere in the environment. If plastics remain in the (aquatic) environment, natural weathering leads to degradation processes and compounds may leach from plastic into the environment. To investigate the impact of degradation process on toxicity of leachates, different types of UV irradiation (UV-C, UV-A/B) were used to simulate weathering processes of different plastic material containing virgin as well as recyclate material and biodegradable polymers. The leached substances were investigated toxicologically using in-vitro bioassays. Cytotoxicity was determined by the MTT-assay, genotoxicity by using the p53-CALUX and Umu-assay, and estrogenic effects by the ERα-CALUX. Genotoxic as well as estrogenic effects were detected in different samples depending on the material and the irradiation type. In four leachates of 12 plastic species estrogenic effects were detected above the recommended safety level of 0.4 ng 17β-estradiol equivalents/L for surface water samples. In the p53-CALUX and in the Umu-assay leachates from three and two, respectively, of 12 plastic species were found to be genotoxic. The results of the chemical analysis show that plastic material releases a variety of known and unknown substances especially under UV radiation, leading to a complex mixture with potentially harmful effects. In order to investigate these aspects further and to be able to give recommendations for the use of additives in plastics, further effect-related investigations are advisable.