Allyl alcohol

Endpoint summary

Description of key information

A total of three key studies have been identified, assessing acute toxicity in the rat following oral and inhalatory exposure and in the rabbit following dermal exposure.  

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

99 mg/kg bw

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

89 mg/kg bw

Additional information

Acute oral toxicity: a method similar to OECD guideline 401 was used. Five male rats were used for each dose group and observed for 10 days post exposure. The main clinical findings were apathy, anxiety, diarrhoea and coma. Gross pathology findings confirm oedema and congestion of the lungs, visceral congestion, discoloured liver (with some necrosis) and swollen discoloured kidneys. The LD50 was determined to be 99 -105 mg/kg. A supporting study (oral administration to rabbits) gave a comparable result: LD50 71 (42 -125) mg/kg

Acute inhalation toxicity: Two studies were identified as having assessed the acute inhalation toxicity of allyl alcohol. The better conducted, key study (performed under GLP) used 10 animals (5 male, 5 female) per dose with whole-body inhalation exposure for 1, 4 and 8 hours at concentrations of 0, 10, 20, 50, 100, 200 and 400 ppm allyl alcohol vapour. Animals were observed over a 14 -day period and surviving animals necropsied. Clinical effects noted included gasping, reddened ears, forelimbs and/or hindlimbs, red or clear material around the mouth and on ventral abdominal or urogentical surfaces in all dose groups.

A weak sedating effect was also seen in the 4 -hour exposure group at doses of 50ppm and 100ppm and also in the 8 -hour exposure group at doses of 20ppm and 50ppm.

Histopathological examination revealed: in 1-hour exposure groups: reversible nasal cavity changes. Degeneration of the olfactory epithelium, metaplasia of olfactory epithelium, chronic inflammation and haemorrhage. In 4-hour exposure groups: reversible nasal cavity changes. Degeneration of respiratory epithelium, degeneration of olfactory epithelium, chronic inflammation and goblet cell hyperplasia. In 8-hour exposure groups: reversible nasal cavity changes (degeneration, erosion, degeneration and erosion of the respiratory epithelium, chronic inflammation, haemorrhage and hyperplasia of goblet cells) plus in 2 males irreversible changes (ulceration, respiratory metaplasia, severe degeneration of olfactory epithelium), with 1 rat dying. With only one death, no LC50 value was determined, but the 4h LC50 value was clearly >100 ppm (237.6 mg/cu.m).

NOAEL values for lethality or irreversible effects in tbis study were: 

1 -hour exposure, 400 ppm

4 -hour exposure, 100 ppm

8 -hour exposure, 20 ppm (males), 50 ppm (females).

The supporting acute inhalation study predated GLP but did follow an accepted test procedure. 6 rats were exposed to concentrations of 40 - 2300 ppm allyl alcohol vapour for 1, 4 and 8 hours and subsequently observed for 10 days. Histopathological findings include lung congestion, liver damage (congestion and necrosis of periportal sinusoids, central pallor and necrosis), presence of heme casts and cloudy swelling in the kidney. LC50 values of 1060, 165, 76 ppm were obtained for male rats exposed to allyl alcohol vapour by inhalation for 1, 4, 8 hours respectively.

Acute dermal toxicity: One key study was identified as having assessed the dermal toxicity of allyl alcohol. The study followed a method similar to OECD guideline 402. Four groups of 3 rabbits were exposed to concentrations of 25 - 200 mg/kg allyl alcohol in occlusive dressing. The main clinical findings were apathy, flushing of the skin with ataxia and diarrhoea preceding death in moribund animals. Gross pathology findings include, oedema and congestion of lungs, visceral congestion (presence of mucous in intestinal tract), discoloured liver, swollen kidneys. The LC50 was determined to be 89 mg/kg.

Justification for classification or non-classification

Acute oral toxicity

Based on the results of the key study (oral LD50 99 - 105 mg/kg), allyl alcohol should be classified as:

- under Directive 67/548/EEC criteria, T - R25 (Toxic if swallowed)

- under UN GHS criteria, Acute Toxicity Category 3 (Toxic if swallowed )

- under Regulation 1272/2008 (EU CLP GHS) criteria, Acute Toxicity Category 3 (Toxic if swallowed).

the DSD and CLP classifications cited above are in accord with those listed for allyl alcohol in

Annex VI of the CLP Regulation (EC No. 1272/2008).

Acute inhalation toxicity

No precise LC50 value was determined in the key study. The supporting study (Dunlap et al., 1958) for allyl alcohol reports a 4-hour LC50 of 165 ppm, which approaches the high end of the Acute toxicity Cat 1 rating. However, the 4-hour NOAEC for lethality in the key study was 100 ppm, and a 1-hour NOAEC for lethality of 400 ppm, which would imply that Cat 1 is likely to be overly conservative. Acute toxicity Cat 2 is proposed. The current entry for allyl alcohol given in Annex VI of the CLP Regulation (EC No. 1272/2008): allyl alcohol is Acute toxicity Cat. 3, inhalation route with an asterisk which indicates the minimum classification. Since the data demonstrates that a more severe classification is appropriate, Acute toxicity Category 2 will be applied to this substance.

Acute dermal toxicity

Based on the results of the key study (rabbit dermal LD50 89 mg/kg), allyl alcohol should be classified as:

- under Directive 67/548/EEC criteria, T - R24 (Toxic in contact with skin)

- under UN GHS criteria, Acute Toxicity Category 2 (Fatal in contact with skin)

- under Regulation 1272/2008 (EU CLP GHS) criteria, Acute Toxicity Category 2 (Fatal in contact with skin).

In Annex VI of the CLP Regulation (EC No. 1272/2008) allyl alcohol is classified as Acute toxicity Cat. 3 (dermal route) with an asterisk which indicates this is the minimum classification to be applied. Since the data indicates that a more severe classification is appropriate, Acute Toxicity Category 2 via the dermal route will will be applied.