1,2-dichloropropane

Endpoint summary

Additional information

Several acute and chronic aquatic toxicity studies with 1,2 -dichloropropane were conducted in fish, invertebrates, algal species, and various microorganisms.

For fish, two valid acute studies and one valid chronic study with fathead minnow were available for assessment. The LC50 of 133 mg/L was based on the geometric mean of the two 96 -hour exposures to fathead minnow. Based on a 32 -day exposure with the fathead minnow, the NOEC was 6 mg/L and based on larvae weight at test termination.

For invertebrates, two valid acute and chronic studies with Daphnia magna and Mysidopsis bahia were available for assessment. The LC50 for freshwater invertebrates was 55.9 mg/L based on a 48 -hour exposure to Daphnia magna. The LC50 for marine water invertebrates was 24.79 mg/L based on a 96 -hour exposure to Mysidopsis bahia. Based on a 21 -day exposure with Daphnia magna, the NOEC for freshwater invertebrates was 8.3 mg/L and based on reproduction. Based on a 28 -day exposure with Mysidopsis bahia, the NOEC for marine water invertebrates was 4.09 mg/L and based on the lack of significant effects on parent survival, reproduction and growth at the highest concentration tested.

For the algal species, one valid study with Skeletonema costatum as the test species was available for assessment. The EC50 and NOEC for the marine water species was 15.4 mg/L and 8.50 mg/L, respectively and based on growth rate following 72 -hours of exposure.

For microorganisms, a variety of toxicity assays were avaliable for assessment and included: Nitrosomonas, Methanogens, Heterotrophs, Microtox, Polytox, and Activated Sludge Respiration Inhibition. The IC50 for microorganisms of 861 mg/L from the activated sludge respiration inhibition test was taken as the most relevant information for assessing effects on sewage treatment facilities.

Taken together, the lowest aquatic toxicity value for 1,2 -dichloropropane was the 28 -day NOEC of 4.09 mg/L based on Mysidopsis bahia parent survival, reproduction and growth. This NOEC value was was equivalent to the highest exposure concentration in the test; therefore, the test design did not incorporate a high enough test concentration to exhibit a toxic response. However, since the the 28 -day Mysidopsis bahia NOEC value was similar to the next lowest aquatic toxicity value, which was the 21 -day Daphnia magna NOEC of 8.3 mg/L, and since the acute value for Mysidopsis bahia (24.79 mg/L) was approximately half that of the Daphnia magna acute value (55.9 mg/L) and both acute values correlate well with their respective chronic NOEC values, the Mydisopsis bahia 28 -NOEC of 4.09 mg/L is considered a valid, though conservative (worst-case), estimate of aquatic toxicity.