Comparison of Trend Analysis Estimate and Measured Toxicity in Fish Acute Toxicity Test of Sodium n-Decyl Sulfate

Recently, it has become possible to select the test concentration range in the fish acute toxicity test using the trend analysis (TA) estimate by a categorical approach, but few studies have been conducted on comparing the TA estimate with the measured toxicity. In this study, we compared the TA estimate[48-h median lethal concentration (LC50)]and the measured toxicity (96-h LC50) of sodium n-decyl sulfate using medaka (Oryzias latipes).Our results indicated that the estimated and experimental values were 310 and 420 mg L, respectively, and the difference was within 1.5 times. Since the alkyl carbon chain length of sodium n-decyl sulfate is outside the range of alkyl carbon chain lengths in existing data, the TA estimate obtained in this study was considered an unreliable extrapolated value. Therefore, there was a concern that the basis for the determination of the concentration range in the definitive test was weak. However, it is considered possible to determine the test concentration in the definitive test with higher accuracy by considering relevant available information (e.g., 96-h LC50 of other fish species) in addition to the TA estimate.