ABSTRACT
The purpose of this research was to use polyvinyl alcohol (PVOH) 18-88 as a case study to evaluate the environmental fate, ecotoxicity, and overall safety profile of water-soluble, nonmodified PVOH polymers used in detergent films. An OECD 303A Wastewater Treatment Plant Simulation Study was conducted with dissolved organic carbon as the analytical endpoint to evaluate the removal of PVOH 18-88 during wastewater treatment. During the plateau phase, high levels of removal due to biodegradation were observed (average 97.4 ± 7.1, range: 88%-116%). The OECD 303A study quantitatively verified that surface water is the dominant receiving compartment for PVOH 18-88 post wastewater treatment. Acute algae, invertebrate, and fish embryo (fish embryo acute toxicity test [FET]) ecotoxicity studies quanitified the 50% lethal/effect concentration (L/EC50) for PVOH 18-88. Due to the potential for the chorion to impact PVOH 18-88 bioavailability, both chorionated and dechorionated FET tests were conducted. L/EC50 > 1000 mg/L for FET (chorionated and dechorionated), invertebrate, and algae were observed. The Sustainable Futures (US) and REACH (EU) frameworks were used to evaluate environmental risk. For the US assessment, the Exposure and Fate Assessment Screening Tool was used to predict the single day lowest flow over a 10-year period (1Q10) surface water concentration and the seven consecutive days of lowest flow over a 10-year period (7Q10) surface water concentration and compared with acute and chronic concentrations of concern. For the EU assessment, the European Union System for the Evaluation of Substances was used to predict local and regional exposure concentrations and compared to the predicted no effect concentration. For both regulatory assessments, the exposure concentrations were >2 orders of magnitude below the effect concentrations. Integr Environ Assess Manag 2024;00:1-13. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
ABSTRACT
Multiple polyethylene glycol (PEG) polymers ranging in molecular weight (MW) from 4000 to 500,000 Da, polyvinyl alcohol (PVOH) polymers with degrees of hydrolysis (DH) of 79 % and 88 % and MW 10,000 to 130,000 Da, and carboxy methyl cellulose (CMC) polymers with degrees of substitution (DS) ranging from 0.6 to 1.2 were evaluated in standard screening biodegradation tests to assess method limitations, modification potential, and reproducibility. All PEGs and PVOHs mineralized completely in OECD 301B and 302B studies reaching >80 % biodegradation with negligible dissolved organic carbon remaining at study completion. For high MW PEOs, extension of test duration was needed to reach full extent of mineralization. CMC biodegradation was directly correlated to degree of substitution with CMC 0.6 biodegrading extensively, CMC 0.79 partially biodegrading, and CMC 1.2 not biodegrading significantly in OECD 301B and 302B studies. For all materials tested in both an OECD 301B and 302B, fewer days were necessary to reach 60 % biodegradation in the OECD 302B indicating increased rates of biodegradation with higher inoculum to test chemical ratios. In a series of investigative studies using respirometry as the analytical endpoint, significant variability in the presence of competent degraders in small volume grab samples of river water was observed. Research is needed to overcome this variability and develop a standardized reproducible test method to accurately assess polymer mineralization in river water. At study completion, residual dissolved organic carbon (DOC) data confirmed respirometry data, high levels of mineralization resulted in negligible residual DOC while low levels of mineralization resulted in significant residual DOC, up to dose concentrations. DOC measurements provided confirmation of complete biodegradation when biomass incorporation and test system set up resulted in variable carbon dioxide production or oxygen demand.
