Acrolein [factsheet]

ACROLEIN

Please Note: The main sources of information for this fact sheet are EPA's IRIS, which contains information on inhalation chronic toxicity of acrolein and the RfC, and the Agency for Toxic Substances and Disease Registry's (ATSDR's) Toxicological Profile for Acrolein. 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literature, and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.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

* Acrolein can be formed from the breakdown of certain pollutants found in outdoor air, from burning tobacco, or from burning gasoline. (1)

* Airborne exposure to acrolein may occur from breathing contaminated air, from smoking tobacco or proximity to someone who is smoking, or from being near automobiles or oil or coal power plants. In several large cities, acrolein has been measured at 9 ppb. (1)

* Occupational exposure to acrolein could occur in industries that use acrolein to make other chemicals. (1)

* Small amounts of acrolein may be found in some foods, such as fried foods, cooking oils, and roasted coffee. (1)

* Acrolein has not been detected in drinking water, and is not commonly found in surface water. (1)

Assessing Personal Exposure

* There are currently no tests available to determine personal exposure to acrolein. (1)

Health Hazard Information

Acute Effects:

* Acute inhalation exposure to high levels (10 ppm) of acrolein in humans may result in death. Effects on the lung, such as upper respiratory tract irritation and congestion have been noted at acrolein levels ranging from 0.17 ppm to 0.43 ppm. (1-3)

* Acrolein is considered to have high acute toxicity, based on short-term animal tests such as the LC₅₀ test in rats. (1,4)

* EPA's Office of Air Quality Planning and Standards, for a hazard ranking under Section 112(g) of the Clean Air Act Amendments, considers acrolein to be a "high concern" pollutant based on acute chronic toxicity. (5)

Chronic Effects (Noncancer):

* The major effects from chronic (long-term) inhalation exposure to acrolein in humans consist of general respiratory congestion and eye, nose, and throat irritation. (1,2,6)

* Acrolein is a strong dermal irritant, causing skin burns in humans. (1,2,6)

* Animal studies have reported that the respiratory system is the major target organ for acrolein toxicity. (1,2,6)

* The RfC for acrolein is 0.00002 mg/m³ based on squamous metaplasia and neutrophilic infiltration of nasal epithelium in rats. (3)

* EPA has high confidence in the studies on which the RfC was based because adequate numbers of animals were used, careful attention was paid to experimental protocol, and together they demonstrated a consistent profile of histopathological changes in the respiratory system; low to medium confidence in the database due to the lack of chronic data and adequately conducted reproductive or developmental studies; and, consequently, medium confidence in the RfC.

* EPA has not established an RfD for acrolein. (3)

* EPA has calculated a provisional RfD of 0.02 mg/kg/d for acrolein. (7)

Reproductive/Developmental Effects:

* No information is available on the reproductive or developmental effects of acrolein in humans. (1)

* In the one available reproductive animal study, rats were exposed to acrolein by inhalation, with no effects observed on the number of pregnancies or the number and weights of the fetuses. (1)

* Acrolein has been reported to cause birth defects in rats when injected directly into the embryonic tissue. (1)

Cancer Risk:

* No information is available on the carcinogenic effects of acrolein in humans. (1,3)

* Limited animal cancer data are available; one inhalation study in rats reported no evidence of tumors in the respiratory tract or in other tissues and organs, while another study reported an increased incidence of adrenocortical tumors in female rats exposed to acrolein in drinking water. (1,3)

* EPA has classified acrolein as a Group C, possible human carcinogen, based on limited evidence of carcinogenicity in animals, the structural similarity of acrolein to substances possibly carcinogenic to humans, the carcinogenic potential of one of its metabolites, and the lack of human data. (3)

Physical Properties

* Acrolein is a water-white or yellow liquid that burns easily and is easily volatilized. (1)

* Acrolein has a disagreeable odor and an odor threshold of 0.2 ppm. (1,8)

* The chemical formula for acrolein is C₃H₄O and the molecular weight is 56.06 g/mol. (1)

* The vapor pressure for acrolein is 220 mm Hg at 20 EC, and its log octanol/water partition coefficient (Log K_ow) is -0.01. (1)

Uses

* Acrolein is used to make other chemicals and pesticides, and is found in some livestock feeds and pesticides. (1)

Health Data from Inhalation Exposure

Concentration (mg/m³)	Health numbers^a	Regulatory, advisory numbers^b	Reference
1,000.0
_ _ _ _ 100.0	* LC₅₀ (rats) (298 mg/m³)		4
_ _ _ _ 10.0
_ _ _ _ 1.0
_ _ _ _ 0.1	* LOAEL (rats) (0.917 mg/m³)	* ACGIH and OSHA STEL (0.8 mg/m³) * ACGIH TLV, OSHA PEL, and NIOSH IDLH (0.25 mg/m³)	3 6 6
_ _ _ _ 0.01
_ _ _ _ 0.001
_ _ _ _ 0.0001
_ _ _ _ 0.00001	* RfC (0.00002 mg/m³)		3

ACGIH STELCAmerican Conference of Governmental and Industrial Hygienists' short-term exposure limit; 15-min time-weighted-average exposure that should not be exceeded at any time during a workday even if the 8-h time-weighted-average is within the threshold limit value.

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.

(continued)

NIOSH IDLHCNational Institute of Occupational Safety and Health's immediately dangerous to life and health; NIOSH concentration representing the maximum level of a pollutant from which an individual could escape within 30 min without escape-impairing symptoms or irreversible health effects.

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.

OSHA STELCOccupational Safety and Health Administration's short-term exposure limit; 15-min time-weighted-average exposure that should not be exceeded at any time during a workday even if the 8-h time-weighted-average is within the threshold limit value.

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.

References

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Acrolein. U.S. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1989.

2. 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.

3. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on Acrolein. 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). 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. E.J. Calabrese and E.M. Kenyon. Air Toxics and Risk Assessment. Lewis Publishers, Chelsea, MI. 1991.

7. U.S. Environmental Protection Agency. Health Effects Assessment Summary Tables. Annual Update. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

8. 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.