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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

When rainbow trout (O. mykiss) were exposed to Dowfax 2A1, the 96-hour LC50 value was 6.2 mg/L. 

Key value for chemical safety assessment

LC50 for freshwater fish:
6.2 mg/L

Additional information

Three acute freshwater fish studies (summarized in a single report) were assessed for this endpoint. One study was a 96-hour static exposure conducted with rainbow trout (Oncorhynchus mykiss), one study was a 96-hour static exposure conducted with bluegill sunfish (Lepomis machrochirus), and one study was a 96-hour flow-through test conducted with fathead minnows (Pimephales promelas). The static acute toxicity tests with the trout and the bluegill were deemed reliable for use in risk assessments (Klimish score = 2), however, the flow-through test with the fathead minnow was conducted at a lower temperature than recommended for this species, therefore the reported 96-hour LC50 value of 3.85 mg/L Dowfax 2A1 for fathead minnows was not deemed reliable. The acute tests with rainbow trout and bluegill sunfish reported 96-hour LC50 values of 6.2 and 6.81 mg/L Dowfax 2A1, respectively. Since these toxicity tests were conducted with two different fish species, the lower of the two toxicity values (6.2 mg/L) was selected as the key study for this endpoint.

An additional, supporting study was included for this endpoint. In this study effluent spiked with Dowfax 2A1 elicited toxicity to rainbow trout (Oncorhynchus mykiss), whereas non-spiked effluent (negative control) and effluent containing biodegradation products from activated sludge treatment of Dowfax 2A1 did not elicit toxicity to trout.