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Short-term toxicity to fish

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Description of key information

In a well reported, 96 hour acute toxicity to fish study conducted to a scientifically valid but non-standard method, the toxicity of technical-grade dinoseb was tested using channel catfish under standard conditions at 12°C in soft reconstituted water. The 96-h LC50 for technical dinoseb was 0.058 mg/L for channel catfish. Differences among formulated products and technical dinoseb did not affect dinoseb toxicity .

Key value for chemical safety assessment

LC50 for freshwater fish:
0.058 mg/L

Additional information

- The Skelley, 1989 study is presented as the key information as this study gives the lowest LD50 for assessment purposes, and presents a worst case scenario. The reliability rating for this study is 2, the study is an adequately reported non-GLP study not conducted according to standard methodology but with analytical verification of test concentrations. In this study fish (channel catfish) were exposed to dinoseb in static systems for 96hrs. Preliminary tests were used to determine behaviour abnormalities.

The following supporting studies are also available:

- In the Callet al, 1984 study, fathead minnows (Pimephales promelas) 30 d of age were exposed to dinoseb (2-sec-butyl-4,6-dinitrophenol) in flow through tests to determine acute toxicity. Median lethal concentrations (LC50 values) for dinoseb were 0.8, 0.7, 0.7, and 0.5 mg/L at 24, 48, 96 and 192 hours respectively. Early life stages of the fathead minnow were exposed to lower concentrations of each compound for a total of 64 days. The 'no effect' concentration was estimated to lie between 14.5 and 48.5 µg/L for dinoseb. Neither herbicide was appreciably accumulated in fish tissue. Whole body bioconcentration factor for parent14C-dinoseb was 1.4. Rainbow trout (Salmo gairdneri) injected with radio-labelled dinoseb eliminated >83% of the radioactivity within 24h as a combination of parent compound and metabolites.

The reliability rating for this study is 2, according to the criteria of Klimisch, 1997 as the study is an adequately reported non-GLP study not conducted according to standard methodology.

- In the Gersich, F.M. and M.A. Mayes, 1986 study, the static acute toxicity of 2-sec-butyl-4,6 -dinitrophenol (dinoseb) to fat head minnows (Pimephales promelas) was tested.

Dinoseb was highly toxic to fathead minnows, with a reported LC50 value 0.17 mg/L.

The reliability rating for this study is 2, according to the criteria of Klimisch, 1997 as the study is an adequately reported non-GLP study conducted according to ASTM methods.

- In the Skelley, 1989 study, the toxicity of technical-grade dinoseb was tested using fathead minnows under standard conditions at 12°C in soft reconstituted water. The 96-h LC50 for technical dinoseb was 0.088 mg/L for fathead minnows.

The reliability rating for this study is 2, according to the criteria of Klimisch, 1997 as the study is an adequately reported non-GLP study not conducted according to standard methodology.