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Short-term toxicity to aquatic invertebrates

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Description of key information

Parent compound valeryl chloride: no data.
Hydrolysis product valeric acid: acutely harmful to aquatic invertebrates.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
58.2 mg/L

Additional information

Parent compound valeryl chloride:

No data are available for valeryl chloride (CAS 638 -29 -9). The substance rapidly decomposes in water and forms HCl (CAS 7647 -01 -0) and valeric acid (CAS 109 -52 -4). Therefore, the short-term toxicity to aquatic invertebrates is assessed on the basis of data on valeric acid.

Hydrolysis product valeric acid:

The acute toxicity of valeric acid to aquatic invertebrates is evaluated on the basis of a weight-of-evidence approach which considers also read-across from analogue substances. For valeric acid (CAS 109 -52 -4) there is only a publication with insufficient documentation available. The 48 -h LC50 determined with the waterflea (Daphnia magna) was 45 mg/L (Dowden & Bennett, 1965).

With the analogue substance isobutyric acid (CAS 79 -31 -2) the acute Daphnia toxicity was tested in a non-GLP study following the German Industrial Standard DIN 38412, part 11 (similar to OECD 202). The 48 -h EC50 was determined to be 51.25 mg/L (BASF, 1989).

In a similar study following EU method C.2, Daphnia magna were exposed to the analogue substance 2 -ethylhexanoic acid (CAS 149 -57 -5). The 48 -h EC50 was 85.4 mg/L (BASF, 1988).

The geometric mean of the LC/EC50 values of these three studies is 58.2 mg/L.


The results are supported by an acute toxicity study with "Isopentanoic acid (mixed isomers)", a commercial mixture of 64% n-pentanoic acid and 36% 2 -methyl-1 -butyric acid. Waterfleas (Daphnia magna) were exposed to this mixture according to OECD 202 (Daphniasp., Acute Immobilisation Test). The EC50 (48 h) was 88.1 mg/L and the NOEC was 65.2 mg/L (ECHA, 2011).

Hydrolysis product hydrochloric acid (HCl):

The hydrolysis product hydrochloric acid (HCl) was tested in a semi-static acute toxicity test according to OECD 202 with Daphnia magna. The 48-h EC50 was 0.492 mg/L (acid equivalent to pH 5.3; OECD 2002).