Methacrylic acid

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Principles of method if other than guideline:

MAA aerosol/vapor (aerosol mass median diameter: 10, 6.5, 5.5, 7.2 um)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Methacrylic acid

EC Number:

201-204-4

EC Name:

Methacrylic acid

Cas Number:

79-41-4

Molecular formula:

C4H6O2

IUPAC Name:

methacrylic acid

Test material form:

liquid

Specific details on test material used for the study:

2-propenoic acid, 2-methyl (methacrylic acid (MAA), Glacial Methacrylic acid
Lot 5-031342
Haskell No H-19762
purity: 98.5 %
clear liquid

Test animals

Species:

rat

Strain:

other: Crl:CD BR

Sex:

male/female

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

aerosol/vapor atmosphere

Analytical verification of test atmosphere concentrations:

yes

Remarks:

aerosol: gravimetric; vapor: gas chromatography

Duration of exposure:

4 h

Concentrations:

4.3, 5.9, 7.3, 8.2 mg/L

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

Rats observed for 13-14 days and body weights collected.

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

7.1 mg/L air

Based on:

other: mixed exposure vapour/aerosol

Exp. duration:

4 h

Remarks on result:

other: saturated vapour approx 3.4-3.7 mg/L, aerosol 3,19 – 6.5 mg/l

Mortality:

Deaths occured at 5.9 mg/L or greater

Clinical signs:

other: In the 8.2 mg/l group all rats died during exposure. In the 7.3 mg/l group, two female rats died during exposure. One male rat was found dead on test day 2 and one male rat was found dead on test day 7. Following exposure, typical clinical observations we

Other findings:

Mortality is clearly associated with exposure to aerosol. Exposure to (saturated) vapour was +/- the same at all concentration levels (3.4-3.7 mg/L). Exposure to vapour alone was not associated with mortality, while exposure to aerosol increased (0.9-4.7 mg/L) in parallel to an increase in mortality.

Any other information on results incl. tables

SUMMARY OF MAA CHAMBER CONCENTRATIONS AND ASSOCIATED RAT MORTALITY

TOTAL ATMOSPHERIC CONCENTRATION (mg/L)		AEROSOL/VAPOR CONCENTRATION RATIO *(%)	VAPOR CONCENTRATION	AEROSOL CONCENTRATION	MORTALITY (# DEATHS/# EXPOSED)
MEAN	N		MEAN  ST.DEV.	MEAN  ST.DEV.	MALES	FEMALES
4.3	8	21 / 79	3.4 +/- 0.17	0.91 +/- 0.26	0 / 5	0 / 5
5.9	9	37 / 63	3.7 +/- 0.24	2.2 +/- 0.94	0 / 5	1 / 5
7.3	8	50 / 50	3.7 +/- 0.27	3.6 +/- 0.41	2 / 5	2 / 5
8.2	9	57 / 43	3.6 +/- 0.20	4.7 +/- 1.8	5 / 5	5 / 5

* Aerosol/vapor ratios were calculated using the mean aerosol and vapor concentrations for each exposure.

Aerosol mass median diameters were 10, 6.5, 5.5, or 7.2 µm for concentrations of 4.3, 5.9, 7.3, 8.2 mg/L, respectively.

Applicant's summary and conclusion

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

Using a valid experimental method, the 4 hour LC50 of MAA to male and female rats was 7.1 mg/L (1983 ppm; vapour/aerosol mix).
Mortality is clearly associated with exposure to aerosol. Exposure to (saturated) vapour was +/- the same at all concentration levels (3.4-3.7 mg/L). Exposure to vapour alone was not associated with mortality, while exposure to aerosol increased ( 0.9-4.7 mg/L) in parallel to an increase in mortality.

Executive summary:

Rats (5m/5f) were exposed to a vapour/aerosol mix at four doses between 4.3 and 8.2 mg/L (1201 - 2291 ppm) acc. OECD 403..

Mortality is clearly associated with exposure to aerosol. Exposure to (saturated) vapour was +/- the same at all concentration levels (3.4-3.7 mg/L). Exposure to vapour alone was not associated with mortality, while exposure to aerosol increased ( 0.9-4.7 mg/L) in parallel to an increase in mortality (measured aerosol concentration: 3.6 +/- 0.41 mg/l to 4.7 +/- 1.8 mg/l).

The 4 hour LC50 of MAA to male and female rats was 7.1 mg/L air (vapour/aerosol mix).

Classification is based on mortality to aersol : LC50 (inhal.) 3,19 – 6.5 mg/l