A Weight of Evidence Analysis of the Chronic Ecotoxicity of Nonylphenol Ethoxylates, Nonylphenol Ether Carboxylates, and Nonylphenol

ABSTRACT

Nonylphenol ethoxylates (NPE) are widely used surfactant compounds with many domestic and industrial applications. Due to the nature of their use in down-the-drain applications, spent NPE are discharged to septic systems or to wastewater treatment plants. Biodegradation of parent material during treatment is often incomplete, leading to release of NPE and their degradation intermediates into the environment. Considerable aquatic toxicity research has occurred on NPE and particularly on nonylphenol (NP). Available data were subjected to a quality review and all studies of acceptable quality were used in a weight of evidence hazard assessment. Data for NP were further analyzed using a Species Sensitivities Distribution (SSD) approach. About 90 chronic values are available (ChVs, geometric mean of the no-observed effect concentration and lowest-observed effect concentration for each endpoint reported), which may be reduced to average ChVs for each tested species. Higher mole NPE (NPE ≥ 9) had ChVs ranging from 900 to 14,100 μg/L, ChVs for the low mole nonylphenol ether carboxylate (NPEC1) ranged from 3200 to 12,000 μg/L, ChVs for lower mole NPE (NPE1,2) ranged from 11 to 500 μg/L, and ChVs for NP ranged from 5 to 3500 μg/L. Using the SSD analysis for NP with higher quality study results, the 10th percentile chronic effect value is 5.7 μg/L, which supports the draft USEPA criteria on NP of 5.9 μg/L.

Keywords:

• hazard assessment
• endocrine modulation
• NPE
• species sensitivity distribution.

ACKNOWLEDGMENT

The preparation of this manuscript was sponsored by the Alkylphenol and Ethoxylate Research Council, Washington, DC, USA.