Ecotoxicological hazard assessment of two polymers of distinctively different molecular weights

Assessment of ecological risks during manufacturing, use, transport, and disposal are becoming increasingly important as planning tools during development of new products. The objective of this study was to establish the potential ecotoxicological hazard associated with two polycarboxylate polymers in water, sludge, sediment, and soil. The concentrations of both polymers were quantified using 14C-radiolabeled synthesis and liquid scintillation counting (LSC). The program included water column acute and chronic exposures with Ceriodaphnia dubia, Pimephales promelas, and Selenastrum capricornutum, sediment exposures with Chironomus riparius, and soil exposures with Eisenia foetida. Sludge treated with either polymer, from a semicontinuous activated sludge unit, was used to evaluate the effect on growth of five plants. The hazard assessment program for both polymers indicated a very low order of toxicity as defined by the U.S. EPA and OECD. Very small fractions of each polymer may not be removed by waste treatment and could accumulate in sediments, but should not pose a significant risk because of their low toxicity to benthic organisms. Terrestrial testing demonstrated that soil needs to be saturated with these chemicals to produce adverse effects. Bioaccumulation potential for both polymers was extremely low. Use of these polymers does not appear to pose a significant risk to the environment, based on their low inherent toxicity.