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Short-term toxicity to aquatic invertebrates

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Description of key information

Parent compound isovaleryl chloride: No data available.
Hydrolysis product isovaleric acid: No data available.
Because there are no data available for the parent compound and its hydrolysis product, the short-term toxicity to aquatic invertebrates is assessed on the results of the structurally similar substance isobutyric acid.
Isobutyric acid/valeric acid: Acutely harmful to aquatic invertebrates.
Hydrolysis product HCl: Acutely very toxic for aquatic invertebrates (pH-dependent).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
58.2 mg/L

Additional information

Parent compound isovaleryl chloride and hydrolysis product isovaleric acid:

Isovaleryl chloride (CAS 108 -12 -3) rapidly decomposes in water and forms HCl (CAS 7647 -01 -0) and isovaleric acid (CAS 503 -74 -2). Since there are neither experimental data available for isovaleryl chloride nor for its hydrolysis product isovaleric acid, short-term toxicity to aquatic invertebrates is assessed via read across to the structurally similar substances isobutyric acid (CAS 79 -31 -2) and valeric acid (CAS 109 -52 -4).

Isobutyric acid

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).

Valeric acid

The result for isobutyric acid can be confirmed by the assessment for 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).

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 (Daphnia sp. , Acute Immobilisation Test). The EC50 (48-h) was 88.1 mg/L and the NOEC was 65.2 mg/L (ECHA, 2011).

Based on the available data the test substance isovaleryl chloride and its hydrolyis product are assessed to be acutely harmful to aquatic invertebrates.

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).