WP8 Beyond Occurrence: Fate and Effects of Pharmaceutical and Other Emerging Wastewater Contaminants in Aquatic Systems
Wednesday, 16 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(KLE-1117-827542) Exposure Analysis of Alkylphenol, Alkylphenol Ethoxylates and Their Metabolites in U.S. Surface Waters.

Zabik, J¹, Klecka, G¹, Woodburn, K¹, Naylor, C², Staples, C³, ¹ The Dow Chemical Company, Midland, MI, USA² Huntsman Corporation (retired), Austin, TX, USA³ Assessment Technologies Inc, Spotsylvania, VA, USA

ABSTRACT- Over the past 17 years numerous investigations have examined the levels of alkylphenol ethoxylates (APEO) and their metabolites (APEM) in U.S. surface waters. The available literature was critically reviewed and used to develop a database of environmental monitoring data. A statistical analysis of the available monitoring data suggested that while maximum reported concentrations appear to increase with time, the average environmental concentrations have remained relatively constant. In addition, despite widespread use, APEO/APEM are typically detected in less than 40 percent of the samples. Because the sampling strategies for the more recent monitoring studies have focused on the analysis of areas which are susceptible to contamination, it is suggested that the apparent increasing trends are not representative of increased usage or emissions over time, but rather are a function of sample location. To develop a probabilistic description of environmental exposures and their ecological significance, the frequency distribution of environmental levels were compared to the U.S. EPA draft Water Quality Criteria for nonylphenol (NP), and to probabilistic descriptions of ecological effects as defined by species sensitivity distributions. Examination of the percent rank of aggregated APEO concentrations (adjusted according to their relative toxicities) suggests that less than 5% of the samples contained aggregate NP equivalent concentrations that exceed the criterion. A probabilistic risk assessment for total NP equivalent impact on U.S. aquatic ecosystems indicated that the likelihood of a surface water concentration exceeding the draft criterion for NP is approximately 6% or less, indicating an infrequent or low probability of occurrence.

Key words: Alkylphenol ethoxylates, Surface water, Environmental monitoring, Environmental risk assessment