4-[3-(1-naphthylamino)propyl]morpholine

Endpoint summary

Description of key information

One valid acute freshwater fish study was available for 4-(3-(1-naphthylamino)propyl)morpholine. The study was a static, 96-hour exposure with the fathead minnow, Pimephales promelas, and was conducted according to OECD TG 203. This study was assigned a Klimisch score of 2 based on the lack of analytical confirmation of test concentrations used in the study. The test was performed under static conditions with five concentrations, a dilution water control and a solvent control (0.1 ml/L dimethylformamide) at a temperature of 22 ± 1 °C. The reported 96-hour LC50 value was 4.8 mg/L based on nominal concentrations. The 95% confidence intervals for the LC50 were 4.2 – 5.4 mg/L. The 96-hour NOEC value was 2.2 mg/L.

One static acute toxicity test with Daphnia magna was available for 4-(3-(1-naphthylamino)propyl) morpholine. This study was assigned a Klimisch score of 2 based on the lack of analytical measures of test solution concentrations. The 48-hour EC50 value (based on immobility) was reported as 5.1 mg 4-(3-(1-naphthylamino)propyl) morpholine/L with a 95% confidence interval of 4.4 - 6.0 mg/L. This value was based on initial nominal concentrations. Thus, the key parameter for the acute invertebrate endpoint was the EC50 value of 5.1 mg/L.

One static toxicity study with the green algae, Selenastrum capricornutum,was available for review and was found to be of good quality and reliable for use in the risk assessment process (Klimisch score = 2). The Klimisch score for this study was 2 due to the lack of analytical confirmation of test concentrations in this study. This study measured both growth rate (r) and biomass as indicators of growth inhibition over 72 hours of exposure to 4-(3-(1-naphthylamino)propyl) morpholine.  Under the conditions of the study, the 72-hour no observed effect concentration was 0.63 mg 4-(3-(1-naphthylamino)propyl) morpholine /L. The 72-hour EC50 was 1.0 mg/L when calculated using the number of cells/ml and 2.6 mg/L when calculated using the average specific growth rate.  The 72-hour EC50 based on growth rate is the preferred parameter for summarizing toxicity to aquatic algae, therefore, this value was selected as the key value for this endpoint.

Of these aquatic toxicity values, the 72-hour ErC50 of 2.6 mg/L for growth inhibition in the algae was the lowest value reported, and this data point was used in the development of the PNECaqua.