Abstract
Most thermoplastics contain a variety of additive chemicals that can represent a high percentage of the final plastic materials (up to 50%). The current study characterised the chemical content of freshwater and marine leachates produced from CTR, PP, PET, PS and PVC, and assessed their adverse effects on freshwater (Raphidocelis subcapitata) and marine (Skeletonema costatum) microalgae. PP, PET, PS, PVC (cryomilled, 1000 µm sieved fraction) and car tire rubber (CTR)-derived granulate (1-2 mm) were subjected to a non-target screening for organic additive chemicals by solvent extraction and analysis by GC-MS. Leachates of material were generated in seawater, marine algae growth media and freshwater algae growth media. Metal leachates were characterized by ICP-MS and organic additives by solvent extraction followed by GC-MS. Leachate toxicity towards R. subcapitata and S. costatum was determined as inhibition of growth over 72 h.
A range of organic additive chemicals were identified in the polymer materials and used as a basis for studying the additive compounds in the leachates. The highest number of organic compounds was found in PP (19), followed by CTR (17), PVC (9), PS (9) and PET (1). The concentrations of the different additives were material-specific and varied from tens of ng to hundreds of µg/L. The trends in organic additive concentrations were similar between freshwater and marine media for organic compounds, but more varied for inorganics. Leachate toxicity varied between the different polymers and there were observable differences between the two algal species for some leachates. CTR produced the most toxic leachate, with EC50 values of 0.5% and 19% of total leachate towards the freshwater and marine algae, respectively. PP exhibited a similar toxicity towards marine algae to that observed for CRT (EC50 18%), but showed the lowest toxicity towards freshwater algae (EC50 64%). PVC had high toxicity towards freshwater algae (EC50 1.6% of total leachate), but the second lowest toxicity towards marine algae (EC50 35%). The higher toxicity of CTR and PVC leachates was directly linked to the higher additive chemical content of these leachates. This study provides new knowledge on the chemical characterisation and ecotoxicological effects of chemical additive leachates from plastic and rubber materials under freshwater and marine conditions.
A range of organic additive chemicals were identified in the polymer materials and used as a basis for studying the additive compounds in the leachates. The highest number of organic compounds was found in PP (19), followed by CTR (17), PVC (9), PS (9) and PET (1). The concentrations of the different additives were material-specific and varied from tens of ng to hundreds of µg/L. The trends in organic additive concentrations were similar between freshwater and marine media for organic compounds, but more varied for inorganics. Leachate toxicity varied between the different polymers and there were observable differences between the two algal species for some leachates. CTR produced the most toxic leachate, with EC50 values of 0.5% and 19% of total leachate towards the freshwater and marine algae, respectively. PP exhibited a similar toxicity towards marine algae to that observed for CRT (EC50 18%), but showed the lowest toxicity towards freshwater algae (EC50 64%). PVC had high toxicity towards freshwater algae (EC50 1.6% of total leachate), but the second lowest toxicity towards marine algae (EC50 35%). The higher toxicity of CTR and PVC leachates was directly linked to the higher additive chemical content of these leachates. This study provides new knowledge on the chemical characterisation and ecotoxicological effects of chemical additive leachates from plastic and rubber materials under freshwater and marine conditions.