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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

In a growth inhibition test with Pseudokirchnerella subcapitata, the 72-hour ErC50 for epichlorohydrin was 15 mg/L.  The 72-hour NOEC for epichlorohydrin was determined to be 1.7 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
15 mg/L
EC10 or NOEC for freshwater algae:
1.7 mg/L

Additional information

Two toxicity tests with the green algae, Pseudokirchnerella subcapitata,were assessed for reliability, and both studies were found to be of good quality and reliable for use in the risk assessment process. One algal toxicity study measured both growth rate (r) and biomass (y) as indicators of growth inhibition over 72 hours of exposure.  The 72-hour ErC50 for growth rate in this study with P. subcapitata was 15 mg/L epichlorohydrin. The 72-hour NOEC and EyC50 (based on biomass) in this same study with P. subcapitata were reported as 1.7 and 7.1 mg/L epichlorohydrin, respectively. In the other reliable algal toxicity test with P. subcapitata, the 96-hour EC50 for epichlorohydrin was determined by examining both cell number and total cell volume. Each endpoint was examined in repeat algal tests to examine the precision of the assay. Therefore, the 96-hour EC50 values (based on cell number) were 13 mg/L and 16 mg/L epichlorohydrin, and the 96-hour EC50 values (based on total cell volume) were 16 mg/L and 17 mg/L epichlorohydrin. Since the use of the average specific growth rate for estimating toxicity is scientifically preferred (OECD 201, 2006), the 72-hour NOEC and ErC50 of 1.7 and 15 mg/L epichlorohydrin, respectively, were selected as the key parameters for this endpoint.