"Assessing Ecological Risk Posed by Nonylphenol with Species Sensitivity Distribution Method " 

Ken-ichi Miyamoto, Akihiro Tokai, Junko Nakanishi

National Institute of Advanced Industrial Science and Technology

Society of Environmental Toxicology and Chemistry 23rd Annual Meeting (Salt Lake City, USA 2002/11/20)

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Abstract

Nonylphenol is one of the chemicals of most concern in terms of ecological risk. Canada and the EU have recently completed risk assessment for it and recommended considering risk reduction. 

The US EPA is in the process of developing ambient aquatic life criteria. Japan’s Ministry of the Environment published a draft risk assessment report last year. Among them, the US EPA’s draft criteria and the Canadian assessment report use the species sensitivity distribution (SSD) method, which is known to be more sophisticated than the quotient method.

However, the chronic SSDs for nonylphenol in these two documents were derived from acute toxicity data with a geometric mean of acute-chronic ratios that largely differ among species. The purpose of this study is to derive a chronic SSD for nonylphenol from chronic toxicity data directly and to apply it to the risk assessment for Japan’s aquatic environment. 

The SSD was described as a lognormal distribution using nine chronic toxicity data from two plants and seven animals, after the Anderson-Darling goodness-of-fit test was performed. The potentially affected fraction (PFA) of 5% was used as the preliminary benchmark for the risk assessment. 

Exposure concentrations used in this assessment were surveyed in 555 aquatic areas all over Japan by the Ministry of the Environment and the Ministry of Land, Infrastructure and Transport from 1999 to 2001. Ten areas exceeded 5% PFA only once, three areas twice, and two areas three times. 

Because most of the exposure concentrations used were measured once or twice per year, their representativeness and/or exposure concentration distributions should be considered further. 

Keywords

ノニルフェノール,生態リスク評価,種の感受性分布