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Description of key information

Methyl acrylate is of moderate toxicity after single ingestion and after short-term skin contact. Methyl acrylate is of pronounced toxicity after short-term inhalation.
Oral: LD50 = ca. 768 mg/kg bw (rat, BASF Test)
Dermal: LD50: ca. 1250 mg/kg bw (rabbit, occlusive)
Inhalation: LC50 = <10.382 mg/L (rat, comparable to OECD TG 403)

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
Value:
768 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50
Value:
10 382 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
Value:
1 250 mg/kg bw

Additional information

Oral exposure route:

 

In the key study conducted by BASF AG (1958) groups of 5 male rats were administered doses of 196, 303, 481, 762 and 1210 mg/kg bw and observed for 7 days for lethality and clinical signs of intoxication. The LD50 was found to be approx. 768 mg/kg bw. Clinical symptoms were unspecific: staggering, apathy, labored breathing. At necropsy, lesions of the gastric mucosa were found. Other acute oral LD50s in rats, rabbits and mice were described in literature mostly without additional data and ranged between 277 and 826 mg/kg bw (Smyth & Carpenter 1948, Tanii 1982, BASF 1960, Treon 1949).

Dermal exposure route:

 

The dermal LD50 in rabbits was determined as 1250 mg/kg bw. Clinical signs were not reported (Smyth 1948). In another study (BASF 1958) rabbits were exposed to a dose of 0.2 mL/kg bw of the test substance (corresponding to approx. 190 mg/kg bw) on the back under occlusive conditions for a period of 24 hours. 3/3 animals survived without any clinical signs of intoxication. Local signs of irritation (slight erythema) were observed. Since only one dose of 190 mg/kg bw was tested and that dose did not result in any lethality, this study can at best be seen as support of the previous mentioned study, but does not add any further data. Other studies with rats and rabbits are not reliable due to significant methodological deficiencies and are therefore not suitable for assessment (Treon 1949, BASF 1958).

 

Inhalation exposure route:

 

The key study, conducted according to OECD guideline 403 by BASF in 2012, indicates that the LC50 is less than 10.362 mg/L. There are several acute vapour inhalation toxicity studies available involving Sprague-Dawley rats, NMRI mice, and Chinese hamsters conducted by BASF AG (1979) according to an internal method equivalent to OECD guideline 403. The studies were performed with fasted and non-fasted animals, but tests with fasted animals are not taken into consideration for the hazard assessment, since fasting represents a physiological stress situation and is not in accordance with the guideline. Nonetheless, the effect values from the six studies were all in the same range, between 2.5 (hamster, non-fasted) and 6.5 (rat, non-fasted) mg/L.

In the key study, five groups of 10 Sprague-Dawley rats/dose/sex were exposed (whole-body) to methyl acrylate vapours at nominal concentrations of 11.8, 11.7, 8.8, 5.8, and 4.4 mg/L for 4 hours. Test substance concentrations were determined continuously by GC/FID (total hydrocarbons analyzer, CARLO ERBA). Analytically measured test substance concentrations were 3.1, 5.7, 6.7, 8.6 and 10.9 mg/L. The LC50 for both sexes was 6.5 mg/L. Clinical signs included strong eye and nasal irritation and dyspnoea. Within 1 to 7 days, the surviving animals were without symptoms. At necropsy, victims showed acute dilatation of heart, hyperemia and edema of lungs.

Silver and Murphy (1981) investigated the effect of pretreatment with the carboxylesterase inhibitor TOTP on acute inhalation toxicity. Without pretreatment the LC50 in rats after an 4 -hour exposure was > 2.7 - < 3.6 mg/L. Pretreatment with TOTP enhanced the acute toxicity of MA. Older publications by Vernot et al. (1977) and Smyth and Carpenter (1948) in rats do not add any valuable information. Treon et al. (1949) determined for a 1-hour vapour exposure in rabbits an LC50 value of 8.7 mg/L.

Taking all the presented data into consideration, Methyl acrylate was concluded to be of moderate toxicity after single ingestion and after short-term skin contact. Methyl acrylate is of pronounced toxicity after short-term inhalation.

Justification for classification or non-classification

EU classification according to Annex I of Directive 67/548/EEC: Xn, R20/21/22

GHS classification (GHS UN rev.3, 2009):

- Oral route: Acute Category 4

- Dermal route: Acute Category 4

- Inhalation route (vapour): Acute Category 3