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Short-term toxicity to fish

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Description of key information

The 96 h LC50 to the fathead minnow was >27 mg/L under flow-through conditions. 

Key value for chemical safety assessment

LC50 for freshwater fish:
27 mg/L

Additional information

Two data sources on the acute toxicity of 2,6-xylenol to fish species are available.

In the key study, the acute toxicity of the test material to fish was investigated using methodology comparable to that outlined in the standardised guideline OECD 203. It was considered that there was sufficient information on methods and results to evaluate the data and the study was therefore awarded a reliability score of 2 in accordance with the criteria for assessing data quality as set forth by Klimisch et al. (1997).

Pimephales promelas were exposed to the test material under flow-through conditions for 96 hours and static conditions for 48 hours. The flow-through test vessels were two comparable 2-L/cycle proportional diluters, each with a dilution factor of 0.6. Flow-through acute exposure chambers consisted of all-glass aquaria 30 x 30 x 60 cm with a water volume of 41 L. Diluters were cycled at a rate sufficient to give 10 tank volumes/day.

At the start of each flow-through test, 50 fish were randomly assigned to each of the 12 exposure tanks. Dead fish were counted and removed four times during the first day and twice daily thereafter. Twenty fish were used in each exposure chamber in the static tests. Each diluter system had five test concentrations and a control, all duplicated, totalling 12 exposure tanks.

The 48 hour LC50 under static conditions was determined to be 6.7 mg/L.

Under the conditions of this study, 2,6-xylenol had a 96 hour flow-through LC50 value greater than 27 mg/L (based on mortality).

In the supporting study, the acute toxicity of the test material to fish was investigated in accordance with the standardised guideline OECD 203 under GLP conditions. The study was conducted by the Japanese Ministry of the Environment and the available data suggested that the study should be awarded a reliability score of 2 in accordance with the criteria for assessing data quality as set forth by Klimisch et al. (1997).

Oryzias latipes were exposed to the test material for 96 hours. Under the conditions of this study, the 96 h LC50 based on mobility was 15 mg/L.