Registration Dossier
Registration Dossier
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EC number: 227-006-8 | CAS number: 5593-70-4
Toxicity to microorganisms
Administrative data
Link to relevant study record(s)
Description of key information
Testing is not scientifically justified as this substance is hydrolytically unstable. Therefore, the read-across result of the 16-h toxicity threshold of n-butanol to Pseudomonas putida (cell multiplication) based on the nominal concentrations is used as key value in CSA.
Key value for chemical safety assessment
- EC10 or NOEC for microorganisms:
- 650 mg/L
Additional information
As the target substance hydrolyses rapidly (half-life < 5 minutes), the toxicity to microorganisms is related to the main organic degradation product (n-butanol) of the target substance. Therefore, it was justified to use the toxicity of the main decomposition product as a key value in CSA.
Based on the biodegradability of n-butanol as measured in a 20-d BOD assay using unacclimated sewage seed of 68 % ThOD in 5 days, 87 % BOD in 10 days, and 92 % after 15 days, n-butanol is expected to be easily biodegraded in municipal sewage treatment plants outfitted with at least secondary treatment (i.e., biological treatment). Based on the aqueous solubility (63 200 mg/l), negligible accumulation onto sewage sludge particles is expected. Based on this study by Price et al. (1974) it can be concluded that n-butanol released from the target substance has no inhibitory effects on activated sludge.
According to the ECHA Guidance on information requirements and chemical safety assessment, in absence of activated respiration test, toxicity results to microbial bacteria can be used for evaluate the inhibitory effects of chemicals to STP micro-organisms. Therefore, the result of the P.putida cell multiplication inhibition test of the organic hydrolyzing product (n-butanol) is used to calculate the PNEC STP (Bringmann & Kuhn 1980).
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