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Description of key information

The oral LD50 of valeraldehyde was determined to be 6490 mg/kg bw in male rats (BASF, 1977).
The inhalation LC50 of valeraldehyde was determined to be 14.3 mg/L in rats (Smyth, 1969).
The dermal LD50 of valeraldehyde was determined to be 4857 mg/kg in male rabbits (Smyth, 1969).

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
Value:
6 490 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50
Value:
14 300 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
Value:
4 857 mg/kg bw

Additional information

Acute toxicity: oral

 

For the assessment of the acute oral toxicity of valeraldehyde, two valid studies are available (Smyth 1969, BASF 1977; both RL 2). In the study of Smyth, the highest dose tested did not cause any lethality (LD0 = 4582 mg/kg bw). In the BASF study, a LD50 could be determined (LD50 = 6490 mg/kg bw; highest dose tested 8109 mg/kg bw, mortality 8/10 animals). Thus the BASF study is taken as key study with its LD50 of 6490 mg/kg bw.

In the older study of Smyth (1962), the LD50 was determined to be 3850 mg/kg bw. However, the test substance (1-pentanal) is indicated as "mixed isomer" causing doubts on the nature of the test material as a single substance. Thus, the reliability is rated to be 3 and the LD50 is disregarded.

 

BASF 1977

 

The acute oral toxicity of valeraldehyde was determined in groups of 5 male and 5 female Sprague-Dawley rats receiving the test material by oral gavage at doses of 3760, 5520, 8110 mg/kg bw. The observation period was 14 days. The LD50 was estimated using a graphical evaluation of the dose response curve on probability paper. Overall, the study was conducted in accordance with the recently retracted OECD test guideline 401.

 

The acute oral LD50 was determined to be 6490 mg/kg bw in rats (BASF, 1977).

 

Smyth (1969)

 

The acute oral toxicity of valeraldehyde was determined in groups of 5 male Carworth-Wistar rats receiving the test material by oral gavage. The doses were spaced by a factor of 2 (logarithmically). The observation period was 14 days. The LD50 was calculated according to the method of Thomson (1947). No fractional mortality was observed for valeraldehyde at the various doses tested. Thus there was no mortality at the highest dose. No limits of standard deviations could be calculated. Overall, the study was conducted in accordance with the recently retracted OECD test guideline 401.

 

The acute oral LD0 was determined to be 4582 mg/kg bw in rats (Smyth et al., 1969) (LD50 > 4582 mg/kg bw).

 

Acute toxicity: inhalation

 

To assess the acute inhalation toxicity potential of valeraldehyde, only one valid study is available (Smyth, 1969). In the older study of Smyth (1962), the test substance (1-pentanal) is indicated as "mixed isomer" causing doubts on the nature of the test material as single substance (RL 3). In the study of Salem (1969), only one test concentration was used and exposure time was 10 h given that the test animals survived this time (RL 3).

 

Smyth (1969)

 

For this acute inhalation toxicity study, a standard graduate dose test and an inhalation hazard test were performed. The observation period for both tests was 14 days.

 

Groups of six albino rats were exposed for 4 hours to graduate doses of valeraldehyde vapor in the breathing atmosphere of test animals. Doses were spaced in a logarithmic series with a factor of 2. Actual concentrations were not measured and individual doses are not reported.

 

In the inhalation hazard test, test animals were exposed for various time periods starting from one forth hour up to 8 hours (if appropriate; spacing factor of 2) to an atmosphere saturated or close to saturation with vapor of valeraldehyde. Actual atmosphere concentrations were not measured but can be estimated to be saturated or close to saturation by the method, the atmosphere was generated (ca. 90 mg/L at 20°C).

 

In the standard test, a concentration of 4000 ppm (ca. 14.3 mg/L) caused a mortality of 3 of 6 animals. This concentration represents the LC50.

 

In the inhalation hazard test (saturated vapor), the exposure time was restricted to 15 min in order to produce no mortality.

 

A LC50 value using a statistical method was not determined. But the concentration causing 3 deaths out of 6 animals is considered to represent the LC50. Thus the concentration of 14.3 mg/L (4000 ppm) is taken as LC50 value (Smyth 1969).

 

Acute toxicity: dermal

 

For assessment of the acute dermal toxicity of valeraldehyde, only one valid study is available (Smyth, 1969). In the older study of Smyth (1962), the test substance (1-pentanal) is indicated as "mixed isomer" causing doubts on the nature of the test material as single substance (RL 3).

 

Smyth (1969)

 

The acute dermal toxicity of valeraldehyde was determined in groups of 4 male albino New Zealand rabbits receiving graduate single doses of test substance per group. Number and quantity of individual doses are not specified. The exposure time was 24 hours followed by an observation period of 14 days. Individual data on mortality, weight development, clinical signs, and gross necropsy findings are not reported. From mortality data, the LD50 and a range of ± 1.96 SD was calculated according to the method of Thomson (1947).

 

The acute dermal LD50 for valeraldehyde was determined to be 4857 mg/kg bw in rabbits (Smyth, 1969).

Justification for classification or non-classification

Acute oral toxicity

 

The LD50 of the key study (BASF, 1977) was 6490 mg/kg bw in rats. This exceeds by far the limit values for classification (2000 mg/kg bw) according to Directive 67/548/EEC and Regulation (EC) No 1272/2008. Classification based on EU regulations is not required.

 

Acute inhalation toxicity

 

The LC50 of valeraldehyde for a 4 h exposure period was determined to be 14.3 mg/L. This value falls in the range of 2 to 20 mg/L (gases and vapours) (Directive 67/548/EEC) or 10.0 to 20.0 mg/L (vapours) (Regulation (EC) No 1272/2008) requiring classification (R20 -Harmful by inhalationor Category 4 respectively).

 

Acute dermal toxicity

 

The LD50 value in rabbits was determined to be 4857 mg/kg bw (Smyth, 1969). This exceeds by far the cut off value of 2000 mg/kg bw for classification according to Directive 67/548/EEC and Regulation (EC) No 1272/2008. Classification based on EU regulations is not required.

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