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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Parent compound butyryl chloride: No data available.
Hydrolysis product butyric acid: No data available, therefore the risk assessment is based on read-across to the structurally similar substance isobutyric acid.
Isobutyric acid: Acutely harmful to aquatic algae and cyanobacteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
53.9 mg/L
EC10 or NOEC for freshwater algae:
33.7 mg/L

Additional information

In aquatic systems, butyryl chloride (CAS 141-75-3) hydrolyses quickly and forms HCl (CAS 7647-01-0) and butyric acid (CAS 107-92-6) (for details see section 5.1.2).


Parent compound butyryl chloride and hydrolysis product butyric acid:

No data are available for butyryl chloride (CAS 141-75-3) and butyric acid (CAS 107-92-6). Therefore, the short-term toxicity to aquatic algae is assessed via read across to the structurally similar substance isobutyric acid (CAS 79-31-2).


Isobutyric acid (CAS 79-31-2): Isobutyric acid was tested on Desmodesmus subspicatus in a study following the German Industrial Standard DIN 38412, part 9 (similar to OECD 201). The 72 -h ErC10 and ErC50 were 33.7 and 53.9 mg/L, respectively (BASF, 1990, 2/0244/89).

The test concentrations were not analytically  monitored. However, it is assumed that the test item remained stable over the exposure period based on a high water solubility (618 g/L, OECD 105, OXEA, 2009), a low vapour pressure (2 hPa at 20 °C, OXEA, 2009) a low Henry's Law constant (0.098 Pa*m³/mol, HENRYWIN v3.20, BASF SE, 2022) and a low adsorption potential (log Kow = 1.1, OXEA, 2009; log Koc = 1.66 according to Franco&Trapp, BASF SE, 2022).



Based on the available data on isobutyric acid the parent compound and its hydrolysis product are assessed to be acutely harmful to aquatic algae and cyanobacteria.