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Ecotoxicological information

Toxicity to microorganisms

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Description of key information

The lowest 3-h EL50 (EC50) was 670 mg/L, and the lowest EL0 (NOEC) was ca. 36 mg/L determined for creosote, a structure-related tar oil. This value is adopted for creosote oil, acenaphthene fraction (wash oil).

Key value for chemical safety assessment

EC50 for microorganisms:
670 mg/L
EC10 or NOEC for microorganisms:
36 mg/L

Additional information

No data about microbial inhibition is available for creosote oil, acenaphthene fraction (wash oil) itself. Instead, results obtained with creosote, a structure-related tar oil, are used for conclusion by analogy. Creosote is closely related to wash oil with major constituent the same as in wash oil. Small differences exist for the concentration of methylnaphthalenes (somewhat lower) and of phenanthrene to fluoranthene (somewhat higher) due to a slightly different distillation range (200 to 355°C for creosote compared to 210 to 300°C for wash oil). Nevertheless, toxicity to STP microorganisms is considered to be similar for both substances as range of constituents correspond closely. Results for creosote will be adopted to characterise the toxicity of wash oil to microorganisms.

A 3-h EC50 of 670 mg/L and a NOEC of ca. 36 mg/L were determined as EL50 and EL0 based on nominal concentration (loading). The values were obtained by measuring the respiration rate of activated sludge of a predominantly domestic sewage (Lebertz, 2002, Institut Fresenius, Germany).