Ecotoxicological Hazard Assessment of Two Polymers of Distinctively Different Molecular Weights

Abstract

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.

Environmental Fate Assessment of Two Synthetic Polycarboxylate Polymers

“…Bioaccumulation is expected to be minimal because both polymers are expected to remain largely sorbed to soil and sediments, and because the molecular weights (>1000) of both polymers essentially preclude their passage through biological membranes. The lack of bioaccumulation has been confirmed in studies with earthworms (Jop et al, 1997).…”

An environmental risk assessment profile of two synthetic polymers

“…As would be predicted based on their relatively high MWs and sorption properties, the PE and RP polymers did not bioaccumulate in earthworms. Measured bioaccumulation factors were very small, 0.03 to 0.04 for PE and 0.12 for RP after 21‐d exposures to polymers dosed in soil [5].…”

“… a All of the toxicity tests reported here are described in detail in Jop et al [5], and effective concentrations are based on 100% active ingredients. …”

“…The aquatic hazard of PE and RP was assessed in a testing program with an alga ( Selenastrum capricornutum ), invertebrate ( Ceriodaphnia dubia ), and fish ( Pimephales promelas )[5]. Acute and chronic testing results are summarized in Table 5.…”

Review: radiolabeled polymers containing covalently bound3Hand14C

“…These margins of safety indicate a low (as defined by US Environmental Protection Agency and and Organisation for Economic Co-operation and Development guidelines) toxicity and bioaccumulation of these polymers. 108 Alginic acid (Figure 14), a common food additive, was radiolabeled via CMC ( Figure 15) derivitization of a portion of the carboxylic acid functionalities and subsequent reduction of the CMC ester with NaBT 4 . Residual (unreduced) CMC esters were cleaved using aqueous boronic acid affording a high specific activity polymer (7.1 mCi/mg).…”