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Description of key information

Several GLP and non-GLP studies according to or similar to OECD guidelines 401, 402 and 403 are available for pure valeric acid and a mixture of valeric acid and 2-methylbutyric acid.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
Value:
4 000 mg/kg bw

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
Value:
2 000 mg/kg bw

Additional information

Oral: 5 studies of acceptable quality are available, 3 studies conducted with pure valeric acid and 2 studies conducted with a mixture of isomers containing 64% valeric acid and 36% 2 -methylbutyric acid. All studies using oil as vehicle (corn oil or olive oil) reported LD50 values clearly greater than 4000 mg/kg bw while the studies using water as vehicle or administering undiluted valeric acid reported LD50s in the range of 1000 -2000 mg/kg bw. This indicates a pH-related effect due to the corrosivity of the substance.

Dermal: a GLP-guideline study (reliable without restrictions) conducted with pure valeric acid in rats reports an LD50 greater than 2000 mg/kg bw. In addition, 3 studies of acceptable quality were conducted with a mixture of isomers containing 64% valeric acid and 36% 2 -methylbutyric acid in rabbits. The resulting LD50 were 1000 mg/kw bw, 0.31 and 0.7 ml/kg bw. The first study conducted in rats is considered to be the most appropriate study as it is the only study that has been conducted with pure valeric acid. Further, rabbits often tend to be very sensitive to acids showing acidosis leading to anaphylactic shock and the classification criteria are referring to rat data.

Therefore, the value from the rat study is considered the most relevant and reliable value.

Inhalation: 4 studies of acceptable quality are available and in all 4 studies no mortality was observed after acute exposure (up to 8h) to saturated vapor of pure valeric acid or a mixture of isomers containing 64% valeric acid and 36% 2 -methylbutyric acid.

Justification for classification or non-classification

According to the annex VI of the council directive 67/548 EEC (amended by directive 83/467 EEC) valeric acid does not need to be classified as acutely toxic via any route of exposure as the oral and dermal LD50 values are greater than 2000 mg/kg bw and no mortality was observed after acute inhalation at saturated vapor concentrations.