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i

1

2 

3

4

5

6

7 IMMEDIATELY DANGEROUS TO LIFE OR HEALTH (IDLH) VALUE PROFILE 

8

9

10

11 FOR 

12

13

14 ACRYLONITRILE 

15 [CAS No. 107-13-1] 

16

17

18

19

20 Department of Health and Human Services 

21 Centers for Disease Control and Prevention 

22 National Institute for Occupational Safety and Health 
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ii

1 DISCLAIMER

2 Mention of any company or product does not constitute endorsement by the National Institute for Occupational 

3 Safety and Health (NIOSH). In addition, citations of Web sites external to NIOSH do not constitute NIOSH 

4 endorsement of the sponsoring organizations or their programs or products. Furthermore, NIOSH is not 

5 responsible for the content of these Web sites. 

6

7 ORDERING INFORMATION

8 This document is in the public domain and may be freely copied or reprinted. To receive NIOSH documents or 

9 other information about occupational safety and health topics, contact NIOSH at 

10 Telephone: 1-800-CDC-INFO (1-800-232-4636) 

11 TTY: 1-888-232-6348 

12 E-mail: cdcinfo@cdc.gov 

13

14 or visit the NIOSH Web site at www.cdc.gov/niosh. 
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iii

1 Foreword 

2

3 Chemicals are a ubiquitous component of the modern workplace. Occupational exposures to chemicals have the 

4 potential to adversely affect the health and lives of workers. Acute or short-term exposures to high concentrations 

5 of some airborne chemicals have the ability to quickly overwhelm workers, resulting in a spectrum of undesirable 

6 health outcomes that may inhibit the ability to escape from the exposure environment (e.g., irritation of the eyes 

7 and respiratory tract or cognitive impairment), cause severe irreversible effects (e.g., damage to the respiratory 

8 tract or reproductive toxicity), and in extreme cases, cause death. Airborne concentrations of chemicals capable 

9 of causing such adverse health effects or of impeding escape from high-risk conditions may arise from a variety of 

10 non-routine workplace situations , including special work procedures (e.g., in confined spaces), industrial 

11 accidents (e.g., chemical spills or explosions), and chemical releases into the community (e.g., during 

12 transportation incidents or other uncontrolled-release scenarios). 

13

14 The “immediately dangerous to life or health air concentration values (IDLH values)” developed by the National 

15 Institute for Occupational Safety and Health (NIOSH) characterize these high-risk exposure concentrations and 

16 conditions [NIOSH 2013]. IDLH values are based on a 30-minute exposure duration and have traditionally 

17 served as a key component of the decision logic for the selection of respiratory protection devices [NIOSH 2004]. 

18 Occupational health professionals have employed these values beyond their initial purpose as a component of the 

19 NIOSH Respirator Selection Logic to assist in developing Risk Management Plans for non-routine work practices 

20 governing operations in high-risk environments (e.g., confined spaces) and the development of Emergency 

21 Preparedness Plans. 

22

23 The approach used to derive IDLH values for high priority chemicals is outlined in the NIOSH Current 

24 Intelligence Bulletin (CIB) 66: Derivation of Immediately Dangerous to Life or Health Values [NIOSH 2013]. 

25 CIB 66 provides 1) an update on the scientific basis and risk assessment methodology used to derive IDLH 

26 values, 2) the rationale and derivation process for IDLH values, and 3) a demonstration of the derivation of 

27 scientifically credible IDLH values using available data resources. 

28

29 The purpose of this technical report is to present the IDLH value for acrylonitrile (CAS # 107-13-1). The 

30 scientific basis, toxicologic data and risk assessment approach used to derive the IDLH value are summarized to 

31 ensure transparency and scientific credibility. 

32

33 John Howard, M.D. 

34 Director 

35 National Institute for Occupational Safety and Health 

36 Centers for Disease Control and Prevention
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iv

1 Content 

2 Foreword __________________________________________________________________________________________ iii

3 Abbreviations________________________________________________________________________________________v

4 Glossary ___________________________________________________________________________________________ vi

5 Acknowledgments ___________________________________________________________________________________ ix

6 1.0 Introduction _________________________________________________________________________________ 1

7 1.1 Overview of the IDLH Value for Acrylonitrile _____________________________________________________ 1

8 1.2 Purpose ___________________________________________________________________________________ 1

9 1.3 General Substance Information_________________________________________________________________ 1

10 2.0 Animal Toxicity Data__________________________________________________________________________ 4

11 3.0 Human Data _________________________________________________________________________________ 8

12 4.0 Summary____________________________________________________________________________________ 8

13 References ________________________________________________________________________________________ 10

14
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v

1 Abbreviations 

2

3 ACGIH American Conference of Governmental Industrial Hygienists 

4 AEGL Acute Exposure Guideline Levels 

5 AIHA American Industrial Hygiene Association 

6 BMC benchmark concentration 

7 BMCL benchmark concentration lower confidence limit 

8 C ceiling 

9 °C degree Celsius 

10 CAS chemical abstract service 

11 CEO cyanoethylene oxide 

12 ERPG Emergency Response Planning Guidelines 

13 °F degree Fahrenheit 

14 IDLH immediately dangerous to life or health 

15 LC50 median lethal concentration 

16 LEL lower explosive limit 

17 LOAEL lowest observed adverse effect level 

mg/m3 18 milligram(s) per cubic meter 

19 NAC National Advisory Committee 

20 NAS National Academy of Sciences 

21 NIOSH National Institute for Occupational Safety and Health 

22 NOAEL no observed adverse effect level 

23 OSHA Occupational Safety and Health Administration 

24 PEL permissible exposure limit 

25 ppm parts per million 

26 RD50 concentration of a chemical in the air that is estimated to cause a 50% decrease in the respiratory 

27 rate 

28 REL recommend exposure limit 

29 SCP Standard Completion Program 

30 STEL short-term exposure limit 

31 TLV threshold limit value 

32 TWA time weighted average 

33 UEL upper explosive limit 

34 WEEL workplace environmental exposure level 
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vi

1 Glossary 

2

3 Acute Exposure: Exposure by the oral, dermal, or inhalation route for 24 hours or less. 

4 Acute Exposure Guideline Levels (AEGLs): Threshold exposure limits for the general public applicable to 

5 emergency exposure periods ranging from 10 minutes to 8 hours. AEGL-1, AEGL 2, and AEGL-3 are 

6 developed for five exposure periods (10 and 30 minutes, 1 hour, 4 hours, and 8 hours) and are distinguished 

7 by varying degrees of severity of toxic effects ranging from transient, reversible effects to life-threatening 

8 effects [NAS 2001]. AEGLs are intended to be guideline levels used during rare events or single once-in-a9 lifetime exposures to airborne concentrations of acutely toxic, high-priority chemicals [NAS 2001]. The 

10 threshold exposure limits are designed to protect the general population, including the elderly, children or 

11 other potentially sensitive groups that are generally not considered in the development of workplace exposure 

12 recommendations (additional information available at http://www.epa.gov/oppt/aegl/). 

13 Acute Reference Concentration (RfC): An estimate (with uncertainty spanning perhaps an order of magnitude) 

14 of a continuous inhalation exposure for an acute duration (24 hours or less) of the human population 

15 (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a 

16 lifetime. It can be derived from a NOAEL, LOAEL, or benchmark concentration, with uncertainty factors 

17 (UFs) generally applied to reflect limitations of the data used. Generally used in USEPA noncancer health 

18 assessments [USEPA 2014]. 

19 Acute Toxicity: Any poisonous effect produced within a short period of time following an exposure, usually 24 

20 to 96 hours. 

21 Adverse Effect: A substance-related biochemical change, functional impairment, or pathologic lesion that affects 

22 the performance of an organ or system or alters the ability to respond to additional environmental challenges. 

23 Benchmark Dose/Concentration (BMD/BMC): A dose or concentration that produces a predetermined change 

24 in response rate of an effect (called the benchmark response, or BMR) compared to background [USEPA 

25 2014] (additional information available at http://www.epa.gov/ncea/bmds/). 

26 Benchmark Response (BMR): A predetermined change in response rate of an effect. Common defaults for the 

27 BMR are 10% or 5%, reflecting study design, data variability, and sensitivity limits used. 

28 BMCL: A statistical lower confidence limit on the concentration at the BMC [USEPA 2014]. 

29 Bolus Exposure: A single, relatively large dose. 

30 Ceiling Value (“C”): U.S. term in occupational exposure indicating the airborne concentration of a potentially 

31 toxic substance that should never be exceeded in a worker’s breathing zone. 

32 Chronic Exposure: Repeated exposure for an extended period of time. Typically exposures are more than 

33 approximately 10% of life span for humans and >90 days to 2 years for laboratory species. 

34 Critical Study: The study that contributes most significantly to the qualitative and quantitative assessment of risk 

35 [USEPA 2014]. 

36

37 Dose: The amount of a substance available for interactions with metabolic processes or biologically significant 

38 receptors after crossing the outer boundary of an organism [USEPA 2014]. 

39 ECt50: A combination of the effective concentration of a substance in the air and the exposure duration that is 

40 predicted to cause an effect in 50% (one half) of the experimental test subjects. 
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vii

1 Emergency Response Planning Guidelines (ERPGs): Maximum airborne concentrations below which nearly all 

2 individuals can be exposed without experiencing health effects for 1-hour exposure. ERPGs are presented in a 

3 tiered fashion with health effects ranging from mild or transient to serious, irreversible, or life threatening 

4 (depending on the tier). ERPGs are developed by the American Industrial Hygiene Association [AIHA 2006]. 

5 Endpoint: An observable or measurable biological event or sign of toxicity ranging from biomarkers of initial 

6 response to gross manifestations of clinical toxicity. 

7 Exposure: Contact made between a chemical, physical, or biological agent and the outer boundary of an 

8 organism. Exposure is quantified as the amount of an agent available at the exchange boundaries of the 

9 organism (e.g., skin, lungs, gut). 

10 Extrapolation: An estimate of the response at a point outside the range of the experimental data, generally 

11 through the use of a mathematical model, although qualitative extrapolation may also be conducted. The 

12 model may then be used to extrapolate to response levels that cannot be directly observed. 

13 Hazard: A potential source of harm. Hazard is distinguished from risk, which is the probability of harm under 

14 specific exposure conditions. 

15 Immediately Dangerous to Life or Health (IDLH) condition: A situation that poses a threat of exposure to 

16 airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse 

17 health effects or prevent escape from such an environment [NIOSH 2004, 2013]. 

18 IDLH value: A maximum (airborne concentration) level above which only a highly reliable breathing apparatus 

19 providing maximum worker protection is permitted [NIOSH 2004, 2013]. IDLH values are based on a 30-

20 minute exposure duration. 

21 LC01: The statistically determined concentration of a substance in the air that is estimated to cause death in 1% of 

22 the test animals. 

23 LC50: The statistically determined concentration of a substance in the air that is estimated to cause death in 50% 

24 (one half) of the test animals; median lethal concentration. 

25 LCLO: The lowest lethal concentration of a substance in the air reported to cause death, usually for a small 

26 percentage of the test animals. 

27

28 LD50: The statistically determined lethal dose of a substance that is estimated to cause death in 50% (one half) of 

29 the test animals; median lethal concentration. 

30 LDLO: The lowest dose of a substance that causes death, usually for a small percentage of the test animals. 

31 LEL: The minimum concentration of a gas or vapor in air, below which propagation of a flame does not occur in 

32 the presence of an ignition source. 

33 Lethality: Pertaining to or causing death; fatal; referring to the deaths resulting from acute toxicity studies. May 

34 also be used in lethality threshold to describe the point of sufficient substance concentration to begin to cause 

35 death. 

36 Lowest Observed Adverse Effect Level (LOAEL): The lowest tested dose or concentration of a substance that 

37 has been reported to cause harmful (adverse) health effects in people or animals. 

38 Mode of Action: The sequence of significant events and processes that describes how a substance causes a toxic 

39 outcome. Mode of action is distinguished from the more detailed mechanism of action, which implies a more 

40 detailed understanding on a molecular level. 
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viii

1 No Observed Adverse Effect Level (NOAEL): The highest tested dose or concentration of a substance that has 

2 been reported to cause no harmful (adverse) health effects in people or animals. 

3 Occupational Exposure Limit (OEL): Workplace exposure recommendations developed by governmental 

4 agencies and non-governmental organizations. OELs are intended to represent the maximum airborne 

5 concentrations of a chemical substance below which workplace exposures should not cause adverse health 

6 effects. OELs may apply to ceiling, short-term (STELs), or time-weighted average (TWA) limits. 

7 Peak Concentration: Highest concentration of a substance recorded during a certain period of observation. 

8 Permissible Exposure Limit (PEL): Occupational exposure limits developed by OSHA (29 CFR 1910.1000) or 

9 MSHA (30 CFR 57.5001) for allowable occupational airborne exposure concentrations. PELs are legally 

10 enforceable and may be designated as ceiling, STEL, or TWA limits. 

11

12 Point of Departure (POD): The point on the dose–response curve from which dose extrapolation is initiated. 

13 This point can be the lower bound on dose for an estimated incidence or a change in response level from a 

14 concentration-response model (BMC), or it can be a NOAEL or LOAEL for an observed effect selected from 

15 a dose evaluated in a health effects or toxicology study. 

16 RD50: The statistically determined concentration of a substance in the air that is estimated to cause a 50% (one 

17 half) decrease in the respiratory rate. 

18 Recommended Exposure Limit (REL): Recommended maximum exposure limit to prevent adverse health 

19 effects based on human and animal studies and established for occupational (up to 10-hour shift, 40-hour 

20 week) inhalation exposure by NIOSH. RELs may be designated as ceiling, STEL, or TWA limits. 

21 Short-Term Exposure Limit (STEL): A worker’s 15-minute time-weighted average exposure concentration that 

22 shall not be exceeded at any time during a work day. 

23 Target Organ: Organ in which the toxic injury manifests in terms of dysfunction or overt disease. 

24 Threshold Limit Values (TLVs®): Recommended guidelines for occupational exposure to airborne 

25 contaminants, published by the American Conference of Governmental Industrial Hygienists (ACGIH). TLVs 

26 refer to airborne concentrations of chemical substances and represent conditions under which it is believed 

27 that nearly all workers may be repeatedly exposed, day after day, over a working lifetime, without adverse 

28 effects. TLVs may be designated as ceiling, short-term (STELs), or 8-hr TWA limits. 

29 Time-Weighted Average (TWA): A worker’s 8-hour (or up to 10-hour) time-weighted average exposure 

30 concentration that shall not be exceeded during an 8-hour (or up to 10-hour) work shift of a 40-hour week. 

31 The average concentration is weighted to take into account the duration of different exposure concentrations. 

32 Toxicity: The degree to which a substance is able to cause an adverse effect on an exposed organism. 

33

34 Uncertainty Factors (UFs): Mathematical adjustments applied to the POD when developing IDLH values. The 

35 UFs for IDLH value derivation are determined by considering the study and effect used for the POD, with 

36 further modification based on the overall database. 

37 Workplace Environmental Exposure Levels (WEELs): Exposure levels developed by the American Industrial 

38 Hygiene Association (AIHA) that provide guidance for protecting most workers from adverse health effects 

39 related to occupational chemical exposures expressed as a TWA or ceiling limit.

40

41 
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ix

1 Acknowledgments 

2

3 This document was developed by the Education and Information Division (Paul Schulte, Ph.D., Director). G. 

4 Scott Dotson, Ph.D., was the project officer and lead NIOSH author for this technical report. The basis for this 

5 document was a report contracted by NIOSH and prepared by Andrew Maier, Ph.D., Ann Parker, and Lynn 

6 Haber, Ph.D. (Toxicology Excellence for Risk Assessment [TERA]). 

7

8 Education and Information Division 

9 Devin Baker, M.Ed. 

10 Charles L. Geraci, Ph.D. 

11 Thomas J. Lentz, Ph.D. 

12 Richard Niemeier, Ph.D. 

13 Chris Sofge, Ph.D. 

14

15 NIOSH would like to acknowledge the contribution of the following subject matter experts for their critical 

16 technical review of this report. 

17

18 Michael S. Bisesi, Ph.D., R.E.H.S., C.I.H., Senior Associate Dean for Academic Affairs; Director, Center 

19 for Public Health Practice; Interim Chair & Associate Professor, Division of Environmental Health 

20 Science, College of Public Health, Ohio State University 

21

22 Richard B. Schlesinger, Ph.D., Fellow A.T.S., Senior Associate Dean for Academic Affairs and Research 

23 Professor of Biology, Dyson College of Arts and Sciences, Pace University 

24

25

26

27
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1

1 1.0 Introduction 

2 1.1 Overview of the IDLH Value for Acrylonitrile

3

4 IDLH Value: 60 ppm 

5

6 The IDLH value for acrylonitrile is based on a BMCL05 for lethality of 1,784 ppm in rats exposed for 30 minutes 

7 [Appel et al. 1981]. A composite uncertainty factor of 30 was applied to account for extrapolation from a lethal 

8 concentration threshold in animals, interspecies differences and human variability. The IDLH value for 

9 acrylonitrile is set at 60 ppm. 

10

11 1.2 Purpose 

12

13 This IDLH Value Profile presents (1) a brief summary of technical data associated with acute inhalation 

14 exposures to acrylonitrile and (2) the rationale behind the Immediately Dangerous to Life or Health (IDLH) value 

15 for acrylonitrile. IDLH values are developed based on the scientific rationale and logic outlined in the NIOSH 

16 Current Intelligence Bulletin (CIB) 66: Derivation of Immediately Dangerous to Life or Health (IDLH) values 

17 [NIOSH 2013]. As described in CIB 66, NIOSH performs in-depth literature searches to ensure that all relevant 

18 data from human and animal studies with acute exposures to the substance are identified. Information included in 

19 CIB 66 on the literature search includes pertinent databases, key terms, and guides for evaluating data quality and 

20 relevance for the establishment of an IDLH value. The information that is identified in the in-depth literature 

21 search is evaluated with general considerations that include description of studies (i.e., species, study protocol, 

22 exposure concentration and duration), health endpoint evaluated, and critical effect levels (e.g., NOAELs, 

23 LOAELs, LC50 values). For acrylonitrile, the in-depth literature search was conducted through February 2014. 

24

25 1.3 General Substance Information 

26

27 Chemical: Acrylonitrile 

28 CAS No: 107-13-1 

Synonyms: 2-Propenenitrile; Cyanoethylene; Vinyl cyanide; Fumigrain; Ventox* 29

Chemical category: Nitriles† 30

31 Structural formula:
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2

1

2

3 Table 1 highlights selected physiochemical properties of acrylonitrile relevant to IDLH conditions. Table 2 

4 provides alternative exposure guidelines for acrylonitrile. Table 3 summarizes the Acute Exposure Guidelines 

5 Level (AEGL) values for acrylonitrile. 

6

7 Table 1: Physiochemical Properties of Acrylonitrile 

8

Property Value 

Molecular weight 53.06‡

Chemical formula C3H3N 

Description Colorless to pale-yellow liquid 

Odor Sharp onion-garlic odor

Odor Threshold 1.6 ppm§

UEL 28%*

LEL 2.8%†

Vapor pressure 109 mmHg at 25°C (77°F)‡

Flash point -5°C (23°F)†

 - closed cup

Ignition temperature 480°C (896°F)†

Solubility Soluble in water†

Abbreviation: oC – Celsius; o 9 F – Fahrenheit; mmHg – millimeter mercury; LEL – lower explosive limit; UEL – 

10 upper explosive limit 

References: *

 NLM [2014]; † IFA [2014]; ‡ HSDB [2014]; § 11 AIHA [1989] 

12

13 Table 2: Alternative Exposure Guidelines for Acrylonitrile

14

Organization Value 

Revised (1994) IDLH value* 85 ppm 

NIOSH REL† 1 ppm, TWA cancer; 10 ppm, 15-minute ceiling, skin 

OSHA PEL[2014]^

 2 ppm, TWA; 10 ppm, 15-minute ceiling, skin 

ACGIH TLV [2014] ‡ 2 ppm, TWA 

AIHA ERPG [2010]+

 ERPG-1: 10 ppm; ERPG-2: 35 ppm; ERPG-3: 75 ppm 

AIHA WEEL [2010] § Not available 

15 Abbreviation: ACGIH – American Conference of Governmental Industrial Hygienists; AIHA – American 

16 Industrial Hygiene Association; ERPG – Emergency Response Preparedness Guidelines; IDLH – immediately 

17 dangerous to life or health; NIOSH – National Institute for Occupational Safety and Health; OSHA – 

18 Occupational Safety and Health Administration; PEL – permissible exposure limit; REL – recommended 

19 exposure limit; SCP – Standards Completion Program; TWA – time-weighted average; WEEL – workplace 

20 environmental exposure level 

References: *

NIOSH [1994]; ^OSHA [2014]; †NIOSH [2014]; ‡ 21 ACGIH [2014]; AIHA [2010a]+; §AIHA 

22 [2010b] 

23 

H2C

N
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1 Table 3: AEGL Values for Acrylonitrile* 

2

Classification 10-min 30-min 1-hour 4-hour 8-hour End Point 

[reference] 

AEGL-1 1.5 ppm 

(3.3 mg/m3) 

1.5 ppm (3.3 mg/m3) 

NR NR NR No-effect level for notabl

(ocular irritation) in hum4.6 ppm for 8 hour [SakuJakubowski et al. 1987]. 

AEGL-2 8.6 ppm 

(19 mg/m3) 

3.2 ppm (6.9 mg/m3) 

1.7 ppm (3.7 mg/m3) 

0.48 ppm (1.0 mg/m3) 

0.26 ppm (0.56 mg/m3) 

No-effect level for fetal tweight) in rats, 12 ppm fo[Saillenfait et al. 1993]. 

AEGL-3 130 ppm 

(280 mg/m3) 

50 ppm (110 mg/m3) 

28 ppm (61 mg/m3) 

9.7 ppm (21 mg/m3) 

5.2 ppm (11 mg/m3) 

No-effect level for lethalihour, and 8-hour BMCL0and Neal 1942; Appel et 

Abbreviation: AEGL – acute exposure guideline levels; mg/m3 3 – milligrams per cubic meter; min – minute; ppm – parts per m

4 References: * NAS [2014] 
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4

1 2.0 Animal Toxicity Data 

2

3 Following acute inhalation exposure to acrylonitrile, the most reported effect is ocular and respiratory irritation, 

4 with convulsions and tremors occurring at higher concentrations. The mechanism by which irritation is caused is 

5 unknown. Central nervous system (CNS) effects are likely a result of the metabolism of acrylonitrile to the 

6 cyanide metabolite, cyanoethylene oxide (CEO). While early seizures are likely due to cyanide formation 

7 metabolism of acrylonitrile, the later severe clonic convulsions prior to death are speculated to be due to 

8 acrylonitrile itself [Ghanayem et al. 1991; Nerland et al. 1989; Benz and Nerland 2005]. Following the formation 

9 of cyanide, it is detoxified to thiocyanate via a rhodanese-mediated pathway. Rhodanese is a mitochondrial 

10 enzyme and identified as meditating one of the primary pathways for the detoxification of cyanide [Cipollone et 

11 al. 2008]. 

12

13 There are notable species differences in the metabolism of acrylonitrile. Dogs are more susceptible to 

14 acrylonitrile than other species following inhalation exposures [Dudley and Neal 1942]. For example, inhalation 

15 exposures to 65 or 100 ppm acrylonitrile for 4 hours caused effects including coma and death in dogs, while 

16 exposures to acrylonitrile at airborne concentrations between 65 to 100 ppm exposures for 4 hours caused 

17 minimal irritation and respiratory change in monkeys, cats or rabbits. Higher airborne concentrations in species 

18 more tolerant did lead to coma, convulsions and death. This difference in toxic susceptibility is thought to be due 

19 to dogs having lower levels of a rhodanese [Drawbaugh and Marrs 1987]. 

20

21 In a lethality study, the LC50 value of rats exposed to acrylonitrile for 4 hours was calculated to be 333 ppm; 

22 deaths occurred within 2-4 hours [Haskell Laboratories 1942]. Reported effects included irregular respiration, 

23 hyperemia, lacrimation, tremors, convulsions and death. Dudley and Neal [1942] investigated the effects of 

24 single acute exposure to acrylonitrile in rats, dogs, cats, monkeys, rabbits and guinea pigs. The reported effects 

25 varied between species and exposure scenarios (i.e., exposure duration and concentration). For example, female 

26 monkeys treated at 65 ppm for 4 hours experienced slight increased respiratory rates. In comparison, dogs 

27 exposed at 65 ppm for 4 hours exhibited severe salivation, weakness, comas and 50% mortality. At 315 ppm 

28 acrylonitrile for 4 hours, rats experienced marked effects and 25% mortality during exposure. Rats treated with 

29 665 ppm acrylonitrile for 30 minutes had moderate transitory effects of ocular and nasal irritation with no 

30 mortality reported [Dudley and Neal 1942]. In a study of rats exposed to 1080 ppm for 1 hour, there were no 

31 deaths, but clinical signs of toxicity included rapid shallow breathing, decreased activity, salivation, lacrimation 

32 [Vernon et al. 1990]. Three of ten animals became comatose, but all of the rats recovered within 5 minutes of 
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5

1 exposure termination. Species differences in metabolism can be observed between rodents and humans. Rats and 

2 mice are reported to form CEO at greater rates than humans [Roberts et al. 1991]. Humans also detoxify CEO 

3 more efficiently than do rodents [Kedderis et al. 1995]. However, evaluation of metabolism and physiologically 

4 based pharmacokinetic modeling results suggest that rats are better than mice as an animal model of human 

5 acrylonitrile inhalation exposure [Appel et al. 1981; NAS 2014]. 

6

7 Table 4 summarizes the LC data identified in animal studies and provides 30-minute equivalent derived values for 

8 acrylonitrile. Table 5 provides non-lethal data reported in animal studies with 30-minute equivalent derived 

9 values. Information in these tables includes species of test animals, toxicological metrics (i.e., LC, BMCL, 

10 NOAEL, LOAEL), adjusted 30-minute concentration, and the justification for the composite uncertainty factors 

11 applied to calculate the derived values.
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1 Table 4: Lethal Concentration Data for Acrylonitrile2

Reference Species LC50

(ppm) 

BMCL05

(ppm) 

Time (min) 

Adjusted 30-min Concentration* (ppm) 

ComposUncertaFactor 

Haskell Laboratory [1942, 1968] Rat 333 -- 240 2,205 30‡ Dudley and Neal [1942] Rat -- 1,024 60 1,924 30‡ WIL Research Laboratories [2005] Rat 946 -- 240 6,264 30‡ Appel et al. [1981]+ Rat -- 1,784 30 1,784 30‡ 

34 Abbreviation: LC – lethal concentration; LC50 – median lethal concentration; BMCL05 – benchmark concentration lower-bound confidenc5 the estimated 95% lower confidence bound on the concentration associated with a 5% increased lethality response above controls; min – mi

*For exposures other than 30 minutes the ten Berge et al. [1986] relationship is used for duration adjustment (Cn 6 x t = k); ten Berge et al. [1

7 estimated n =1.1 for all time-scaling. 8 †The derived value is the result of the adjusted 30-minute LC value divided by the composite uncertainty factor. 9 ‡Composite uncertainty factor to account for the use of lethal concentration threshold in animals, interspecies differences and human variab

+ 10 Identified study is the primary basis of the IDLH value for acrylonitrile. 

111213
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1 Table 5: Non-lethal Concentration Data for Acrylonitrile2

Reference Species NOAEL 

(ppm) 

LOAEL (ppm) 

Time (min) 

Adjusted 30-min Concentration* 

CompoUncertFactor 

Dudley and Neal [1942] Monkey 65 -- 240 430 3‡ Dudley and Neal [1942] Dog 65 240 430 10± Dudley and Neal [1942] Rat 665 -- 30 665 3‡ Vernon et al. [1990] Rat -- 1,080 60 2,028 10± 

Wilson et al. [1948] Humans -- 100 45 145 1 Jakubowksi et al. [1987] Humans 4.5 -- 480 56 1 

3 Abbreviation: NOAEL – no observed adverse effect level; min – minute; LOAEL – lowest observed adverse effect level; ppm – parts per 4 *For exposures other than 30 minutes the ten Berge et al. [1986] relationship is used for duration adjustment (Cn x t = k); ten Berge et al. [15 estimated n =1.1 for all time-scaling. 6 †The derived value is the result of the adjusted 30-min value divided by the composite uncertainty factor. 7 ‡Composite uncertainty factor assigned to account for interspecies differences and human variability. 8 ±Composite uncertainty factor assigned to account for adjusting from a LOAEL to NOAEL, interspecies differences and human variability. 
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8

1 3.0 Human Data 

2

3 Case studies of fatal acute exposures to airborne acrylonitrile are reported. However, because concentrations and 

4 exposure durations were not indicated, no adequate quantitative data for human lethality are available. 

5 Quantitative data are available, however, for non-lethal inhalation exposure to acrylonitrile. Workers exposed to 

6 16-100 ppm acrylonitrile for 20-45 minutes were reported to experience dull headaches, nasal and ocular 

7 irritation, discomfort in the chest, nervousness and irritability [Wilson et al. 1948]. These mild effects were 

8 reversible upon removal from exposure and are not considered escape-impairing. In another study, exposure to 

9 4.6 ppm acrylonitrile for 8 hours resulted in no reported signs or symptoms of toxicity [Jakubowski et al. 1987]. 

10 NAS [2014] cited a personal communication reporting that occupational exposure to 12-15 ppm resulted in ocular 

11 irritation and headache. These effects were not considered escape-impairing. 

12

13 NAS [2014] noted various inhalation cancer assessments for acrylonitrile, and IARC downgraded acrylonitrile 

14 from category 2A - Probably carcinogenic to humans to 2B - Possibly Carcinogenic to Humans, noting that data 

15 relative to human carcinogenicity are inadequate and no causal association exists. NAS [2014] stated that it is 

16 very unlikely that a single acute once-in-a-lifetime exposure to acrylonitrile could cause cancer in humans. 

17 4.0 Summary 

18

19 The IDLH value for acrylonitrile is based on a lethality study by Appel et al. [1981] reported a BMCL05 of 1,784 

20 ppm in rats exposed for 30 minutes. Application of a composite uncertainty factor of 30 to account for 

21 extrapolation from a lethal concentration threshold in animals, animal to human differences and human 

22 variability, yielded an IDLH value for acrylonitrile of 60 ppm. This value is believed to be protective of escape23 impairing, irreversible adverse health effects and deaths associated with exposures to acrylonitrile for 30 minutes 

24 or less. 

25

26 It should be noted that the IDLH value for acrylonitrile differs by more than an order of magnitude from the 

27 AEGL-2 30-minute value, which is intended to represent an airborne concentration of a substance above which it 

28 is predicted that the general population, including susceptible individuals, could experience irreversible or other 

29 serious, long-lasting adverse health effects or an impaired ability to escape [NAS 2001]. The AEGL-2 value for 

30 acrylonitrile is based upon transient effects in rats exposed to 305 ppm for 2 hours [Dudley and Heal 1942; NAS 

31 2014]. NIOSH based the IDLH value for acrylonitrile on the 30-minute BMCL05 value of 1748 ppm from Appel 
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9

1 et al. [1981]. The use of this value as the basis of the IDLH value prevented the need for time duration 

2 adjustment and allowed for the use of a lower uncertainty factor. Additionally, the IDLH value aligns closely 

3 with the AEGL-3 30 minute value for acrylonitrile, which is intended to represent an airborne concentration of a 

4 substance above which it is predicted that the general population, including susceptible individuals, could 

5 experience life-threatening health effects or death [NAS 2001]. 

6
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10

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represent and should not be construed to represent any agency determination or policy. 

12

1 Roberts AE, Kedderis GL, Turner MJ, Rickert DE, Swenberg JA [1991]. Species comparison of acrylonitrile 

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