AN ENVIRONMENTAL RISK ASSESSMENT PROFILE OF 2 SYNTHETIC-POLYMERS

A number of environmental fate and effects studies on two distinctly d ifferent polycarboxylates were conducted as part of a product stewards hip program. These studies led to the development of an environmental risk assessment for the two materials. Polymer emulsion (PE) is a typi cal anionic, styrene acrylic polymer (MW 50,000-60,000) used in coatin g applications. Resin polymer (RP), insoluble at neutral pH but increa singly soluble at pH greater than or equal to 8, is a neutral-charged, styrene-acrylic polymer (molecular weight 4,500-9,000) used primarily for graphic arts products. Some amount of both materials will enter t he environment given their use and disposal patterns. Their environmen tal fate is driven by physical-chemical characteristics. Both polymers demonstrated low biodegradation and bioaccumulation potential and str ong sorption to soils, sludge, and sediments in laboratory and/or fiel d studies. Ecotoxicity test results on a variety of plant and animal s pecies indicated a very low order of acute and chronic toxicity. The e nvironmental risk assessment included characterization of exposure in relevant environmental matrices, characterization of adverse effects o r hazards to receptors for which there are complete exposure pathways, and characterization of risk by comparison of predicted exposure leve ls to adverse effect threshold levels. Based on conservative exposure assumptions, the safety margins established in this assessment indicat e that the use of PE and RP, in both commercial and household applicat ions, presents a very low risk to aquatic organisms in the water colum n and sediments, as well as to terrestrial plants, invertebrates, and wildlife. These polymers are also compatible with wastewater and solid waste treatment systems.