Acrylic acid [factsheet]

ACRYLIC ACID

Please Note: The main source of information for this fact sheet is EPA's Integrated Risk Information System (IRIS), which contains information on the inhalation chronic toxicity of acrylic acid and the RfC, and the oral chronic toxicity of acrylic acid and the RfD. Other secondary sources include the Hazardous Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature, and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.

Environmental/Occupational Exposure

* Exposure to acrylic acid occurs primarily in the workplace via inhalation and dermal contact during its manufacture or use. (1,2)

* Consumers may be exposed to acrylic acid in polishes, paints, coatings, rug backings, adhesives, plastics, textiles, and paper finishes. (1)

* Acrylic acid may be released in wastewater and as emissions during its production and use. Individuals may be exposed by inhaling ambient air or ingesting contaminated water. (1)

* Acrylic acid is also produced naturally by some species of algae. (1)

Assessing Personal Exposure

* No information was located regarding the measurement of personal exposure to acrylic acid.

Health Hazard Information

Acute Effects:

* Acrylic acid is a strong irritant to the skin, eyes, and mucous membranes in humans. The liquid may cause blindness if splashed into the eye. (1,2)

* Acute (short-term) exposure of rats to acrylic acid by inhalation has been observed to produce nose and eye irritation, lung hemorrhage, and degenerative changes in the liver and kidneys. (3)

* Tests involving acute exposure of animals, such as the LC₅₀ and the LD₅₀ tests in rats, mice, and rabbits, have demonstrated acrylic acid to have moderate acute toxicity by inhalation or ingestion, and high acute toxicity by dermal exposure. (4)

Chronic Effects (Noncancer):

* Information on the chronic (long-term) effects of acrylic acid in humans is not available. (3)

* In mice and rats chronically exposed to acrylic acid by inhalation, lesions of the nasal mucosa were observed. (3)

* Reduced body weights and altered organ weights were observed in rats orally exposed to acrylic acid. (3)

* The RfC for acrylic acid is 0.0003 mg/m³ based on degeneration of the nasal olfactory epithelium in mice. (3)

* EPA has medium confidence in the study on which the RfC was based because although it was well conducted and identified a lowest-observed-adverse-effect level (LOAEL) for a mild occurrence of the most sensitive effect, a no-observed-adverse-effect level (NOAEL) was not identified, a small number of animals were used, and there is limited description of the nasal lesion reported; medium confidence in the database due to lack of chronic data; and, consequently, medium confidence in the RfC.

* The RfD for acrylic acid is 0.08 mg/kg/d based on reduced pup weight in rats. (3)

* EPA has high confidence in the principal studies on which the RfD is based because a sufficient number of animals were used and all relevant endpoints were reported thoroughly; high confidence in the database because it contains two developmental studies and two chronic studies of good quality, all of which are consistent in identifying the critical effect; and consequently high confidence in the RfD.

* EPA's Office of Air Quality Planning and Standards, for a hazard ranking under Section 112(g) of the Clean Air Act Amendments, has evaluated acrylic acid for chronic toxicity and has given it a composite score of 10 (scores range from 1 to 100, with 100 being the most toxic). These scores are nonlinear and are the product of two ratings: based on the minimal-effect-dose and a rating based on the type of effect. (5)

Reproductive/Developmental Effects:

* No information is available on the reproductive or developmental effects of acrylic acid in humans.

* Decreased body weight gain and decreased fertility were reported in one study of rats exposed to acrylic acid by ingestion although the decrease in fertility was not statistically significant compared with the control. (3)

* Embryotoxic and teratogenic effects (birth defects) were observed in rats injected with acrylic acid. (6)

Cancer Risk:

* No information is available on the carcinogenic effects of acrylic acid in humans.

* In one study, squamous cell carcinomas of the skin were reported in mice treated topically with acrylic acid. Other animal studies have not reported carcinogenic effects. (7)

* EPA has not classified acrylic acid for carcinogenicity.

Physical Properties

* The chemical formula of acrylic acid is C₃H₄O₂, and it has a molecular weight of 72.06 g/mol. (5)

* Acrylic acid occurs as a corrosive, colorless liquid that is miscible with water. (6,8)

* Acrylic acid has an acrid odor with an odor threshold of 0.094 ppm. (6,8,9)

* The vapor pressure for acrylic acid is 52 mm Hg at 20 EC. (6)

Uses

* Acrylic acid is used in the manufacture of plastics, in latex applications, in floor polish, in polymer solutions for coatings applications, emulsion polymers, paint formulations, leather finishings, and paper coatings. Acrylic acid is also used as a chemical intermediate. (1,8)

Health Data from Inhalation Exposure

Concentration (mg/m³)	Health numbers^a	Regulatory, advisory numbers^b	Reference
10,000.0
_ _ _ _ 1,000.0	* LC₅₀ (mice) (5,300 mg/m³)		4
_ _ _ _ 100.0
_ _ _ _ 10.0	* LOAEL (mice) (14.94 mg/m³)^c	* OSHA PEL (30 mg/m³)	3 4
_ _ _ _ 1.0		* ACGIH TLV and NIOSH REL (6 mg/m³)	4
_ _ _ _ 0.1
_ _ _ _ 0.01
_ _ _ _ 0.001
_ _ _ _ 0.0001	* RfC (0.0003 mg/m³)		3

ACGIH TLVCAmerican Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effects.

LC₅₀ (Lethal Concentration₅₀)CA calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.

LOAELCLowest-observed-adverse-effect level.

NIOSH RELCNational Institute of Occupational Safety and Health's recommended exposure limit; NIOSH-recommended exposure limit for an 8- or 10-h time-weighted-average exposure and/or ceiling.

(continued)

OSHA PELCOccupational Safety and Health Administration's permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek.

RfCCReference concentration.

^a Health numbers are toxicological numbers from animal testing or risk assessment values developed by EPA.

^b Regulatory numbers are values that have been incorporated in Government regulations, while advisory numbers are nonregulatory values provided by the Government or other groups as advice.

^c This LOAEL is from the critical study used as the basis for the EPA RfC.

References

1. U.S. Department of Health and Human Services. Hazardous Substances Data Bank (HSDB, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.

2. M. Sittig. Handbook of Toxic and Hazardous Chemicals and Carcinogens. 2nd ed. Noyes Publications, Park Ridge, NJ. 1985.

3. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on Acrylic Acid. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

4. U.S. Department of Health and Human Services. Registry of Toxic Effects of Chemical Substances (RTECS online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.

5. U.S. Environmental Protection Agency. Technical Background Document to Support Rulemaking Pursuant to the Clean Air ActCSection 112(g). Ranking of Pollutants with Respect to Hazard to Human Health. EPAB450/3-92-010. Emissions Standards Division, Office of Air Quality Planning and Standards, Research Triangle Park, NC. 1994.

6 International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans: Some Monomers, Plastics and Synthetic Elastomers, and Acrolein. Volume 19. World Health Organization, Lyon. 1979.

7. E.J. Calabrese and E.M. Kenyon. Air Toxics and Risk Assessment. Lewis Publishers, Chelsea, MI. 1991.

8. The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th ed. Ed. S. Budavari. Merck and Co. Inc., Rahway, NJ. 1989.

9. J.E. Amoore and E. Hautala. Odor as an aid to chemical safety: Odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. Journal of Applied Toxicology, 3(6):272-290. 1983.