Plastics are synthetic polymers of enormous utility in all fields of human activity and their global production currently exceeds 300 million tons per year, of which a good part has as its final destination aquatic ecosystems. Aware of this reality, the University of Vigo keeps open different lines of research that seek to contribute to reducing the ecological impact of these materials and minimize their potential harmful effects on the environment and health. One of these works is ARPA-ACUA, Environmentally friendly alternatives for polymers and their chemical additives in aquatic environments, a work coordinated by the University of Vigo and which has allowed the establishment of an intense collaboration between the plastics industry, represented by its main Spanish technological center, AIMPLAS, and the Galician university, in this case, through the University of A Coruña QANAP group, an international leader in environmental chemistry, and Ecotox, a research team in Ecotoxicology and Marine Pollution of the Marine Research Center of the UVigo.
It was three years of research, funded with just over 400,000 euros by the Ministry of Economy and Competitiveness, and the conclusions leave no room for doubt: the resins (polymer without additives) of low-density polyethylene (LDPE), PVC and “virgin” polyamide lack toxicity, both newly produced and after environmental aging, while those of the biodegradable polymer polyhydroxybutyrate (PHB) show some toxicity, so, from an ecotoxicological point of view, the scientific recommendation is to be cautious when replacing conventional polymers with biodegradable ones.
“The results of the project will confer competitive advantages to the Spanish plastics industry”
The project, which began in 2016, sought to contribute to the selection of environmentally friendly alternatives with regard to the chemical composition of said polymers and, to achieve this, combined ecotoxicology, environmental chemistry and materials science, with the dual objective of, on the one hand, selecting additives of use for the industry that have a lower impact on the aquatic environment according to ecotoxicological tests with sensitive marine organisms, and on the other hand, carrying out an a priori assessment of the environmental risk of alternative bioplastics with lower persistence and toxicity.
“The resulting synergy allowed us to prepare personalized plastic materials, designed with industrial technology but in collaboration with researchers,” explains Professor Ricardo Beiras, leader of Ecotox and general coordinator of this project. “In this way, we were able to design plastics made up of the same polymer (polyethylene, PVC, etc.) but with different chemical additives, both commercial and alternative, and finally study their toxicity in the aquatic environment,” emphasizes Beiras, who highlights that Ecotox was primarily responsible for developing different sensitive and standardized marine bioassays used by the ICES (International Council for the Exploitation of the Sea). “The results of the project will provide competitive advantages to the Spanish plastics industry considering the growing demand for these new types of environmentally harmless plastics on a global scale,” emphasizes the researcher.
Functional additives are sought that combine industrial utility and the absence of biological effects.
After the study carried out, which lasted for 36 months, the team responsible for the research emphasizes that all the additive materials show some toxicity, both using conventional chemical additives and alternative additives of natural origin, although for LDPE and PVC the alternatives slightly reduce the toxicity. In the case of standard materials this toxicity is related to their content in butyl-hydroxy-toluene (antioxidant) and triclosan (antibacterial). “In this sense, vitamin E is an antioxidant that was found to be non-toxic although its cost is higher”, explains Beiras.
In alternative materials, toxicity can be explained by their content in lawsone (antibacterial), quercetin (UV stabilizer) and, in the case of PVC, monoglyceride (plasticizer). “From our point of view, it is therefore necessary to continue the search for functional additives of these types that allow combining industrial utility and the absence of biological effects,” emphasizes Beiras.
The aging of the tested biodegradable resin (PHB) increased its toxicity, particularly in bioassays of microalgae and copepods, a subclass of small maxillopod crustaceans widely distributed throughout the planet, mainly forming part of the zooplankton.
The research activity of the Ecotox team (CIM-UVigo) has the support of the Xunta de Galicia and the European Union, through its co-financing under the FEDER/FSE Galicia 2014-2020 Operational Program.
Source: DUVI
