Quantitative structure-activity relationships for green algae growth inhibition by polymer particles

Abstract

After use and disposal of chemical products, many types of polymer particles end up in the aquatic environment with potential toxic effects to primary producers like green algae. In this study, we have developed Quantitative Structure-Activity Relationships (QSARs) for a set of highly structural diverse polymers which are capable to estimate green algae growth inhibition (EC50). The model (N = 43, R = 0.73, RMSE = 0.28) is a regression-based decision tree using one structural descriptor for each of three polymer classes separated based on charge. The QSAR is applicable to linear homo polymers as well as copolymers and does not require information on the size of the polymer particle or underlying core material. Highly branched polymers, non-nitrogen cationic polymers and polymeric surfactants are not included in the model and thus cannot be evaluated. The model works best for cationic and non-ionic polymers for which cellular adsorption, disruption of the cell wall and photosynthesis inhibition were the mechanisms of action. For anionic polymers, specific properties of the polymer and test characteristics need to be known for detailed assessment. The data and QSAR results for anionic polymers, when combined with molecular dynamics simulations indicated that nutrient depletion is likely the dominant mode of toxicity. Nutrient depletion in turn, is determined by the non-linear interplay between polymer charge density and backbone flexibility.

Environmental fate and effects of water-soluble synthetic organic polymers used in cosmetic products

“…1 Overview of the environmental fate and aquatic toxicity of the considered water-soluble synthetic polymers based on the evaluated data. Note that in the present evaluation, data for polymers with lower or higher MW than used in cosmetic products were also considered charged surfaces of the test organisms (e.g., [139]). Toxicities of the PQs to aquatic organisms were found to range from absent (i.e., no toxicity) to high, depending on the polymer (PQ-6, -7, -10, or -16), its charge density and MW, the test organism, and test conditions.…”

“…Polyquaterniums In laboratory tests, water-soluble cationic polymers generally have a higher toxicity to aquatic organisms than anionic and non-ionic polymers. Their effects are thought to result from electrostatic interactions with negatively charged biological membranes, including bacterial membranes, the outer cell wall of algae, and respiratory membranes such as the gills [41,117,125,[137][138][139]. Aquatic toxicity of cationic polymers was often found to increase with increasing charge density, especially in water with a low OC content [7,12,42,117].…”

“…Generally, algae were expected to be very sensitive to PQs and other cationic polymers [41,141,142]. Effects were attributed to a disruption of the negatively charged outer cell wall [117,139]. At a sufficiently high concentration, PQs can lead to a flocculation of the algae [32,137,[143][144][145].…”

Toward a Framework for Environmental Fate and Exposure Assessment of Polymers

“…A lack of data on polymer environmental fate will also limit development of polymer QSARs. Although models such as the Ecological Structure-Activity Relationship model include recommendations for assessing the aquatic hazard of polymers (Mayo-Bean et al, 2017), they are limited by availability of data and have been developed only for specific polymer classes, meaning they are often not applicable to new polymers (Nolte, Peijnenburg, et al, 2017).…”

Synergistic effect of copolymeric resin grafted 1,2-benzisothiazol-3(2H)-one and heterocyclic groups as a marine antifouling coating

“…In accordance with the absorbance-concentration curve for the algae dilution, the corresponding concentration of algae was calculated, and the concentration-time curves of algae were plotted. 43,44 Antibacterial activity test…”