Methacrylonitrile

CAS® No. 126-98-7

VALUE PROFILE

IDLH

IMMEDIATELY 

DANGEROUS to

LIFE or HEALTH

Centers for Disease Control

and Prevention

National Institute for Occupational 

Safety and Health
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H3C

H2C

N

Immediately Dangerous to Life or Health (IDLH) Value Profile

Methacrylonitrile

[CAS® No. 126-98-7]

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
ii IDLH Value Profile for Methacrylonitrile

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Suggested Citation

NIOSH [2017]. Immediately dangerous to life or health (IDLH) value profile: methacrylonitrile. By Dotson GS, Maier A, Parker A, Haber L. Cincinnati, OH: U.S. Department of 

Health and Human Services, Centers for Disease Control and Prevention, National Institute 

for Occupational Safety and Health, DHHS (NIOSH) Publication 2017-204.

DHHS (NIOSH) Publication No. 2017-204

September 2017
IDLH Value Profile for Methacrylonitrile	 iii

Foreword

Chemicals are a ubiquitous component of the modern workplace. Occupational exposures 

to chemicals have the potential to adversely affect the health and lives of workers. Acute 

or short-term exposures to high concentrations of some airborne chemicals have the ability 

to quickly overwhelm workers, resulting in a spectrum of undesirable health outcomes 

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

the eyes and respiratory tract or cognitive impairment), cause severe irreversible effects 

(e.g., damage to the respiratory tract or reproductive toxicity), and in extreme cases, cause 

death. Airborne concentrations of chemicals capable of causing such adverse health effects 

or of impeding escape from high-risk conditions may arise from a variety of non-routine 

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

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

(e.g., during transportation incidents or other uncontrolled-release scenarios). 

The immediately dangerous to life or health (IDLH) air concentration values developed 

by the National Institute for Occupational Safety and Health (NIOSH) characterize these 

high-risk exposure concentrations and conditions [NIOSH 2013]. IDLH values are based 

on a 30-minute exposure duration and have traditionally served as a key component of the 

decision logic for the selection of respiratory protection devices [NIOSH 2004]. 

Occupational health professionals have employed these values beyond their initial purpose as a component of the NIOSH Respirator Selection Logic to assist in developing risk 

management plans for non-routine work practices governing operations in high-risk environments (e.g., confined spaces) and the development of emergency preparedness plans. 

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

NIOSH Current Intelligence Bulletin (CIB) 66: Derivation of Immediately Dangerous to Life 

or Health Values [NIOSH 2013]. CIB 66 provides (1) an update on the scientific basis and 

risk assessment methodology used to derive IDLH values, (2) the rationale and derivation 

process for IDLH values, and (3) a demonstration of the derivation of scientifically credible 

IDLH values using available data resources.

The purpose of this technical report is to present the IDLH value for methacrylonitrile 

(CAS® No.126-98-7). The scientific basis, toxicologic data, and risk assessment approach 

used to derive the IDLH value are summarized to ensure transparency and scientific credibility.

John Howard, M.D.

Director

National Institute for Occupational

 Safety and Health

Centers for Disease Control and Prevention
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IDLH Value Profile for Methacrylonitrile	 v

 Contents

Foreword. . 

Abbreviations. .

Glossary. . 

Acknowledgments. .

1 Introduction  

1.1 Overview of the IDLH Value for Methacrylonitrile. 

1.2 Purpose. 

1.3 General Substance Information  

2 Animal Toxicity Data  

3 Human Data. 

4 Summary. 

5 References. 
vi IDLH Value Profile for Methacrylonitrile

Abbreviations

ACGIH® American Conference of Governmental Industrial Hygienists 

AEGLs Acute Exposure Guideline Levels

AIHA® American Industrial Hygiene Association 

BMC benchmark concentration 

BMD benchmark dose

BMCL benchmark concentration lower confidence limit 

C ceiling value

°C degrees Celsius

CAS® Chemical Abstracts Service, a division of the American Chemical Society

CIB Current Intelligence Bulletin

ERPGsTM Emergency Response Planning Guidelines 

°F degrees Fahrenheit

IDLH immediately dangerous to life or health

IFA Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung

(Institute for Occupational Safety and Health of the German Social

Accident Insurance) 

LC lethal concentration

LC01 lethal concentration estimated to cause death in 1% of animals

LC50 median lethal concentration 

LCLO lowest concentration that caused death in humans or animals

LEL lower explosive limit

LOAEL lowest observed adverse effect level 

mg/m3 milligram(s) per cubic meter

min minutes

mmHg millimeter(s) of mercury

NAS National Academy of Sciences

NIOSH National Institute for Occupational Safety and Health

NLM National Library of Medicine

NOAEL no observed adverse effect level 

NR not recommended 

OSHA Occupational Safety and Health Administration

PEL permissible exposure limit 

ppm parts per million 

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

decrease in the respiratory rate

REL recommended exposure limit 

STEL short-term exposure limit 

TLV® Threshold Limit Value 

TWA time-weighted average 

UEL upper explosive limit

WEELs® Workplace Environmental Exposure Levels
IDLH Value Profile for Methacrylonitrile	 vii

Glossary

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

Acute Exposure Guideline Levels (AEGLs): Threshold exposure limits for the general public, 

applicable to emergency exposure periods ranging from 10 minutes to 8 hours. AEGL-1, 

AEGL-2, and AEGL-3 are developed for five exposure periods (10 and 30 minutes, 1 hour, 

4 hours, and 8 hours) and are distinguished by varying degrees of severity of toxic effects, 

ranging from transient, reversible effects to life-threatening effects [NAS 2001]. AEGLs are 

intended to be guideline levels used during rare events or single once-in-a-lifetime exposures 

to airborne concentrations of acutely toxic, high-priority chemicals [NAS 2001]. The threshold 

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

and other potentially sensitive groups that are generally not considered in the development of 

workplace exposure recommendations (additional information available at http://www.epa.

gov/oppt/aegl/). 

Acute reference concentration (Acute RfC): An estimate (with uncertainty spanning perhaps 

an order of magnitude) of a continuous inhalation exposure for an acute duration (24 hours 

or less) of the human population (including sensitive subgroups) that is likely to be without 

an appreciable risk of deleterious effects during a lifetime. It can be derived from a NOAEL, 

LOAEL, or benchmark concentration, with uncertainty factors (UFs) generally applied to 

reflect limitations of the data used. Generally used in U.S. EPA noncancer health assessments 

[U.S. EPA 2016]. 

Acute toxicity: Any poisonous effect produced within a short period of time following an 

exposure, usually 24 to 96 hours [U.S. EPA 2016]. 

Adverse effect: A substance-related biochemical change, functional impairment, or pathologic 

lesion that affects the performance of an organ or system or alters the ability to respond to 

additional environmental challenges. 

Benchmark dose/concentration (BMD/BMC): A dose or concentration that produces a predetermined change in response rate of an effect (called the benchmark response, or BMR) 

compared to background [U.S. EPA 2016] (additional information available at http://www.

epa.gov/ncea/bmds/). 

Benchmark response (BMR): A predetermined change in response rate of an effect. Common 

defaults for the BMR are 10% or 5%, reflecting study design, data variability, and sensitivity 

limits used. 

BMCL: A statistical lower confidence limit on the concentration at the BMC [U.S. EPA 2016]. 

Bolus exposure: A single, relatively large dose. 

Ceiling value (“C”): U.S. term in occupational exposure indicating the airborne concentration 

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

Chronic exposure: Repeated exposure for an extended period of time. Typically exposures are 

more than approximately 10% of life span for humans and >90 days to 2 years for laboratory 

species. 
viii IDLH Value Profile for Methacrylonitrile

Critical study: The study that contributes most significantly to the qualitative and quantitative 

assessment of risk [U.S. EPA 2016].

Dose: The amount of a substance available for interactions with metabolic processes or biologically significant receptors after crossing the outer boundary of an organism [U.S. EPA 2016]. 

ECt50: A combination of the effective concentration of a substance in the air and the exposure 

duration that is predicted to cause an effect in 50% (one half) of the experimental test subjects. 

Emergency Response Planning Guidelines (ERPGsTM): Maximum airborne concentrations 

below which nearly all individuals can be exposed without experiencing health effects for 

1-hour exposure. ERPGs are presented in a tiered fashion, with health effects ranging from 

mild or transient to serious, irreversible, or life threatening (depending on the tier). ERPGs are 

developed by the American Industrial Hygiene Association [AIHA 2006]. 

Endpoint: An observable or measurable biological event or sign of toxicity, ranging from biomarkers of initial response to gross manifestations of clinical toxicity. 

Exposure: Contact made between a chemical, physical, or biological agent and the outer boundary of an organism. Exposure is quantified as the amount of an agent available at the exchange 

boundaries of the organism (e.g., skin, lungs, gut). 

Extrapolation: An estimate of the response at a point outside the range of the experimental 

data, generally through the use of a mathematical model, although qualitative extrapolation 

may also be conducted. The model may then be used to extrapolate to response levels that 

cannot be directly observed. 

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

of harm under specific exposure conditions. 

Immediately dangerous to life or health (IDLH) condition: A condition that poses a threat of 

exposure to airborne contaminants when that exposure is likely to cause death or immediate 

or delayed permanent adverse health effects or prevent escape from such an environment 

[NIOSH 2004, 2013]. 

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

breathing apparatus providing maximum worker protection is permitted [NIOSH 2004, 2013]. 

IDLH values are based on a 30-minute exposure duration. 

LC01: The statistically determined concentration of a substance in the air that is estimated to 

cause death in 1% of the test animals. 

LC50: The statistically determined concentration of a substance in the air that is estimated to 

cause death in 50% (one half) of the test animals; median lethal concentration. 

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

for a small percentage of the test animals.

LD50: The statistically determined lethal dose of a substance that is estimated to cause death 

in 50% (one half) of the test animals; median lethal concentration. 

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

test animals. 
IDLH Value Profile for Methacrylonitrile	 ix

LEL: The minimum concentration of a gas or vapor in air, below which propagation of a flame 

does not occur in the presence of an ignition source. 

Lethality: Pertaining to or causing death; fatal; referring to the deaths resulting from acute 

toxicity studies. May also be used in lethality threshold to describe the point of sufficient 

substance concentration to begin to cause death. 

Lowest observed adverse effect level (LOAEL): The lowest tested dose or concentration of 

a substance that has been reported to cause harmful (adverse) health effects in people or 

animals. 

Mode of action: The sequence of significant events and processes that describes how a substance causes a toxic outcome. By contrast, the term mechanism of action implies a more 

detailed understanding on a molecular level. 

No observed adverse effect level (NOAEL): The highest tested dose or concentration of a substance that has been reported to cause no harmful (adverse) health effects in people or animals. 

Occupational exposure limit (OEL): Workplace exposure recommendations developed by governmental agencies and nongovernmental organizations. OELs are intended to represent the 

maximum airborne concentrations of a chemical substance below which workplace exposures 

should not cause adverse health effects. OELs may apply to ceiling limits, STELs, or TWA 

limits. 

Peak concentration: Highest concentration of a substance recorded during a certain period 

of observation. 

Permissible exposure limits (PELs): Occupational exposure limits developed by OSHA or 

MSHA for allowable occupational airborne exposure concentrations. PELs are legally enforceable and may be designated as ceiling limits, STELs, or TWA limits.

Point of departure (POD): The point on the dose–response curve from which dose extrapolation is initiated. This point can be the lower bound on dose for an estimated incidence or a 

change in response level from a concentration-response model (BMC), or it can be a NOAEL 

or LOAEL for an observed effect selected from a dose evaluated in a health effects or toxicology study. 

RD50: The statistically determined concentration of a substance in the air that is estimated to 

cause a 50% (one half) decrease in the respiratory rate. 

Recommended exposure limit (REL): Recommended maximum exposure limit to prevent 

adverse health effects, based on human and animal studies and established for occupational 

(up to 10-hour shift, 40-hour week) inhalation exposure by NIOSH. RELs may be designated 

as ceiling limits, STELs, or TWA limits. 

Short-term exposure limit (STEL): A worker’s 15-minute time-weighted average exposure 

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

Target organ: Organ in which the toxic injury manifests in terms of dysfunction or overt 

disease. 

Threshold Limit Values (TLVs®): Recommended guidelines for occupational exposure to airborne contaminants, published by the American Conference of Governmental Industrial 
x IDLH Value Profile for Methacrylonitrile

Hygienists (ACGIH®). TLVs refer to airborne concentrations of chemical substances and represent conditions under which it is believed that nearly all workers may be repeatedly exposed, 

day after day, over a working lifetime, without adverse effects. TLVs may be designated as 

ceiling limits, STELs, or 8-hr TWA limits. 

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

exposure concentration that shall not be exceeded during an 8-hour (or up to 10-hour) work 

shift of a 40-hour week. The average concentration is weighted to take into account the duration of different exposure concentrations. 

Toxicity: The degree to which a substance is able to cause an adverse effect on an 

exposed organism.

Uncertainty factors (UFs): Mathematical adjustments applied to the POD when developing 

IDLH values. The UFs for IDLH value derivation are determined by considering the study and 

effect used for the POD, with further modification based on the overall database. 

Workplace Environmental Exposure Levels (WEELs®): Exposure levels developed by the 

American Industrial Hygiene Association (AIHA®) that provide guidance for protecting most 

workers from adverse health effects related to occupational chemical exposures, expressed as 

TWA or ceiling limits.
IDLH Value Profile for Methacrylonitrile	 xi

Acknowledgments

This document was developed by the Education and Information Division Paul Schulte, Ph.D., 

Director. G. Scott Dotson, Ph.D., was the project officer and lead NIOSH author. The basis 

for this document was a report contracted by NIOSH and prepared by Andrew Maier, Ph.D., 

Ann Parker, and Lynn Haber, Ph.D. (Toxicology Excellence for Risk Assessment [TERA]).

The following NIOSH staff are acknowledged for providing technical and editorial review of 

the report:

Education and Information Division 

Devin Baker, M.Ed. 

Charles L. Geraci, Ph.D. 

Thomas J. Lentz, Ph.D. 

Richard W. Niemeier, Ph.D. (retired)

R. Todd Niemeier, MS, CIH

Pranav Rane, M.P.H.

Chris Sofge, Ph.D. 

NIOSH acknowledges the following subject matter experts for their critical technical reviews: 

Ernest V. Falke, Ph.D., Senior Scientist, Risk Assessment Division (RAD), Office of 

Pollution Prevention and Toxics (OPPT), United States Environmental Protection Agency 

(USEPA), Washington, DC

Mary A. Fox, Ph.D., Assistant Professor, Co-Director, Risk Sciences and Public Policy 

Institute, Department of Health Policy and Management, Bloomberg School of Public 

Health, Johns Hopkins University, Baltimore, MD

Tala Henry, Ph.D., Director, RAD, OPPT, USEPA, Washington, DC 

Randall Keller, Ph.D., C.I.H., C.S.P., D.A.B.T., Professor; Occupational Safety and Health 

Department, Jesse D. Jones College of Science, Engineering, and Technology, Murray 

State University, Murray, KY 

Bill Luttrell, Ph.D., Chair and Professor, Department of Chemistry and Physics, College 

of Natural and Health Sciences, Oklahoma Christian University, Edmond, OK

Barry Marcel Ph.D., Environmental Health Consultant, United States Air Force, WrightPatterson Air Force Base, OH

George M. Woodall, Ph.D., Acting Coordinator, Science and Technology Policy Council 

Office of the Science Advisor, USEPA, Research Triangle Park, NC
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IDLH Value Profile for Methacrylonitrile	 1

References: *NLM [2017], †IFA [2017]

1 Introduction 

1.1 Overview of the 

IDLH Value for 

Methacrylonitrile

IDLH value: 4.0 ppm (11 mg/m3)

Basis for IDLH value: Among the acute 

lethality studies, mice and rabbits appear to 

be the most sensitive species. The LC50 values 

in mice and rabbits were 36 and 37 ppm, 

respectively for a 4-hour exposure [Pozzani 

et al. 1968]. In the same study, no deaths or 

clinical signs were reported in mice or rabbits 

exposed to 19.7 ppm for 4-hours, indicating 

a steep concentration-response curve. The 

NOAEL of 19.7 ppm after duration adjustment yields a 30-minute equivalent concentration of 39 ppm. An uncertainty factor of 

10 was applied to account for a steep-dose 

response relationship, animal to human differences, and human variability resulting in 

an IDLH value of 4.0 ppm. 

1.2 Purpose

This IDLH Value Profile presents (1) a brief 

summary of technical data associated with 

acute inhalation exposures to methacrylonitrile 

and (2) the rationale behind the immediately 

dangerous to life or health (IDLH) value for 

methacrylonitrile. IDLH values are developed 

on the basis of the scientific rationale and logic 

outlined in the NIOSH Current Intelligence 

Bulletin (CIB) 66: Derivation of Immediately 

Dangerous to Life or Health (IDLH) Values

[NIOSH 2013]. As described in CIB 66, 

NIOSH performs in-depth literature searches 

to ensure that all relevant data from human 

and animal studies with acute exposures to the 

substance are identified. Information included 

in CIB 66 on the literature search includes 

pertinent databases, key terms, and guides for 

evaluating data quality and relevance for the 

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

search is evaluated with general considerations 

that include description of studies (i.e., species, study protocol, exposure concentration 

and duration), health endpoint evaluated, and 

critical effect levels (e.g., NOAELs, LOAELs, 

and LC50 values). For methacrylonitrile, the 

in-depth literature search was conducted 

through July 2017.

1.3 General Substance Information 

Chemical: Methacrylonitrile

CAS No: 126-98-7

Synonyms: Methylacrylonitrile; 2-methyl-2-Propenenitrile; 2-Cyanopropene-1; 

Isopropene cyanide*

Chemical category: Nitriles†

Structural formula:

H3C

H2C

N
2 IDLH Value Profile for Methacrylonitrile

Table 1 highlights selected physiochemical properties of methacrylonitrile relevant to IDLH 

conditions. Table 2 provides alternative exposure guidelines for methacrylonitrile. Table 3 

summarizes the Acute Exposure Guidelines Level (AEGL) values for methacrylonitrile.

Table 1: Physiochemical properties of methacrylonitrile

Property Value

Molecular weight 67.09*

Chemical formula C4H5N

Description Colorless liquid*

Odor Bitter almond

Odor threshold 6.9 ppm†

UEL 13.2%‡

LEL 1.7%‡

Vapor pressure 65 mmHg at 25°C (77°F)*

Flash point 13°C (55°F)*

Ignition temperature 465°C (869°F)‡

Solubility 2.5% in water; miscible with acetone, octane,

and toluene*

References: *NAS [2014]; †AIHA [2013]; ‡IFA [2017]

Table 2: Alternative exposure guidelines for methacrylonitrile

Organization Value

NIOSH (1994) IDLH value* None

NIOSH REL† 1 ppm (3 mg/m3), 8-hour TWA [skin]

OSHA PEL‡ None

ACGIH® TLV®§ 1 ppm (3 mg/m3), 8-hour TWA [skin]

AIHA® ERPGsTM¶ None 

AIHA® WEELs®¶ None

References: *NIOSH [1994]; †NIOSH [2017]; ‡OSHA [2017]; §ACGIH [2016]; ¶AIHA [2014]
IDLH Value Profile for Methacrylonitrile	

3

Table 3: Interim AEGL values for methacrylonitrile

Classification 10-min 30-min 1-hour 4-hour 8-hour Endpoint [reference]

AEGL-1 NR* NR NR NR NR Insufficient dataAEGL-2 1.3 ppm

3.5 mg/m3

1.3 ppm3.5 mg/m

1.0 ppm2.7 mg/m3

0.67 ppm1.8 mg/m3

0.33 ppm0.89 mg/m3

Three-fold reduction of AEGL-3

AEGL-3 3.9 ppm

11 mg/m3

3.9 ppm11 mg/m3

3.1ppm8.5 mg/m3

2.0 ppm5.5 mg/m3

0.99 ppm2.7 mg/m3

No effect level for lethality in 

mice and rabbits exposed to19.7 ppm for 4 h [Pozzani et al.1968]

Reference: NAS [2014]*Not recommended. Absence of an AEGL-1 value does not imply that exposure below the AEGL-2 value is without adverse effects.
4 IDLH Value Profile for Methacrylonitrile

2 Animal Toxicity Data 

Several acute inhalation studies are available. 

Pozzani et al. [1968] reported 100% mortality 

in rats exposed to 85,500 ppm (essentially saturated vapor) for 3.75-14 minutes. Similarly, 

Younger Labs [1969] found 100% mortality in 

rats exposed to 85,500 ppm for 25 minutes. 

All rats in this latter study exhibited labored 

breathing, pawing at face and nose, cyanosis, and collapse prior to death. Pozzani et al. 

[1968] also exposed several other species in 

addition to rats. They determined LC50 values 

of 36, 37, and 88 ppm, respectively, for mice, 

rabbits and guinea pigs exposed for 4 hours. 

No effect was seen at 19.7 ppm for 4 hours 

in mice or rabbits in the same study. Based 

on the LC50 data, mice and rabbits appear to 

be the most sensitive species. Pozzani et al. 

[1968] also exposed one dog to 52.5 ppm for 7 

hours and one dog each to 106 ppm for 3 and 7 

hours; all of these dogs died. Dupont [1968a] 

exposed an unspecified number of dogs to 87.5 

ppm for 7 hours, resulting in 100% mortality. 

Vomiting, convulsions, unconsciousness and 

irregular breathing were seen in the dogs prior 

to death. No deaths or clinical signs were seen 

in an unspecified number of dogs exposed to 

40 ppm for 7 hours [Dupont 1968b].

Table 4 summarizes the lethal concentration 

(LC) data identified in animal studies and 

provides 30-minute equivalent derived values 

for methacrylonitrile. Table 5 provides non-lethal data reported in animal studies with 

30-minute equivalent derived values. Information in these tables includes species of test animals, toxicological metrics (i.e., LC, BMCL, 

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

the derived values.
IDLH Value Profile for Methacrylonitrile	

5

Table 4: Lethal concentration data for methacrylonitrile

Reference Species

LC50

(ppm)

Other lethality 

(ppm)

Time 

(min)

Adjusted 

30-min 

concentration*

(ppm)

Composite 

uncertainty 

factor

30-min equivalent 

derived

value (ppm)†

Final

value‡ (ppm)

Pozzani et al. [1968] Dog — 52.5§ 420 127 30¶ 4.23 4.0Pozzani et al. [1968] Guinea Pig 88 — 240 176 30¶ 5.87 6.0Pozzani et al. [1968] Mouse 36 — 240 72 30¶ 2.4 2.0Pozzani et al. [1968] Rabbit 37 — 240 74 30¶ 2.46 2.0Pozzani et al. [1968] Rat (male) 328 — 240 656 30¶ 21.9 22Pozzani et al. [1968] Rat (female) 496 — 240 992 30¶ 33.1 33DuPont [1968a] Rat 440 — 240 880 30¶ 29.3 29

*For exposures other than 30 minutes, the ten Berge et al. [1986] relationship is used for duration adjustment (Cn x t = k). No empirically estimated n values were available; therefore,

the default values were used (n = 3 for exposures greater than 30 minutes and n = 1 for exposures less than 30 minutes)

†The derived value is the result of the adjusted 30-minute concentration divided by the composite uncertainty factor.‡Values rounded to the appropriate significant figure.§One dog was exposed and it died.¶Composite uncertainty factor to account for adjustment of LC50 values to LC01 values, use of lethal concentration threshold in animals, interspecies differences, and human variability.
6 IDLH Value Profile for Methacrylonitrile

Table 5: Non-lethal concentration data for methacrylonitrile

Reference Species

Critical adverse

health effects

NOAEL 

(ppm)

LOAEL 

(ppm)

Time 

(min)

Adjusted 

30-min 

concentration*

(ppm) 

Composite 

uncertainty 

factor 

30-min 

equivalent 

derived

value (ppm)†

Final

value‡ 

(ppm)

Pozzani et al. [1968] Mouse No health effected 

associated with this concentration

19.7 — 240 39.4 10§ 3.9 4.0

Pozzani et al. [1968] Rabbit No health effected 

associated with this concentration 

19.7 — 240 39.4 10§ 3.9 4.0

Dupont [1968b] Dog

No health effected 

associated with this concentration

40¶ — 420 94 10§ 9.6 10

*For exposures other than 30 minutes, the ten Berge et al. [1986] relationship is used for duration adjustment (Cn x t = k). No empirically estimated n values were available; therefore,

the default values were used (n = 3 for exposures greater than 30 minutes and n = 1 for exposures less than 30 minutes)

†The derived value is the result of the adjusted 30-minute concentration divided by the composite uncertainty factor.‡Values rounded to the appropriate significant figure.	§Composite uncertainty factor assigned to account for a steep-dose response relationship, interspecies differences and human variability.¶No deaths or clinical signs reported.
IDLH Value Profile for Methacrylonitrile	 7

3 Human Data

No human acute lethality studies were found. 

Only one human exposure study was found 

[Pozzani et al. 1968]. A group of 8–9 volunteers was exposed to various concentrations of 

methacrylonitrile, inhaling each concentration 

twice in the following sequence: 24, 14, 0, 7, 

14, 24, 7, 2, 0, and 2 ppm. One-minute exposures to 24 ppm resulted in nose, throat, and 

eye irritation in 6–22% of the volunteers. A 

few of the volunteers experienced irritation 

during the course of 10-minute exposures to 

2 or 14 ppm.

4 Summary

Among the acute lethality studies, mice 

and rabbits appear to be the most sensitive 

species. The LC50 values in mice and rabbits were 36 and 37 ppm, respectively for 

a 4-hour exposure [Pozzani et al. 1968]. In 

the same study, no deaths or clinical signs 

were reported in mice or rabbits exposed 

to 19.7 ppm for 4-hours, indicating a steep 

concentration-response curve. The NOAEL 

of 19.7 ppm after duration adjustment yields 

a 30-minute equivalent concentration of 39 

ppm. An uncertainty factor of 10 was applied 

to account for a steep-dose response relationship, animal to human differences, and resulting in an IDLH value of 4.0 ppm.

5 References

ACGIH [2016]. Annual TLVs® (Threshold 

Limit Values) and BEIs® (Biological Exposure Indices) booklet. Cincinnati, OH: 

ACGIH Signature Publications.

AIHA [2006]. AIHA Emergency Response 

Planning (ERP) Committee procedures and responsibilities. Fairfax, VA: 

American Industrial Hygiene Association, https://www.aiha.org/get-involved/

AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Documents/

ERP-SOPs2006.pdf.

AIHA [2013]. Odor thresholds for chemicals with established occupational health 

standards. 2nd edition. Fairfax, VA: American Industrial Hygiene Association Press.

AIHA [2014]. Emergency response planning 

guidelines (ERPG) and workplace environmental exposure levels (WEEL) handbook. 

Fairfax, VA: American Industrial Hygiene 

Association Press, https://www.aiha.org/

get-involved/AIHAGuidelineFoundation/

EmergencyResponsePlanningGuidelines/

Documents/2014%20ERPG%20Values.pdf.

DuPont [1968a]. Initial submission: acute 

inhalation toxicity in rats with acrylonitrile 

(uninhibited), methacrylonitrile (inhibited), 

and acetonitrile with cover letter dated 

101592. OTS0571605.

DuPont [1968b]. Initial submission: 

comparative acute inhalation toxicity in 

dogs with acrylonitrile (inhibited) and 
8 IDLH Value Profile for Methacrylonitrile

methacrylonitrile (inhibited) with cover 

letter dated 101592. OTS0571603.

IFA (Institut für Arbeitsschutz der 

Deutschen Gesetzlichen Unfallversicherung) [2017]. GESTIS: database on 

hazardous substances, http://www.dguv.de/

ifa/gestis/gestis-stoffdatenbank/index-2.jsp. 

NAS [2001]. Standing operating procedures 

for developing Acute Exposure Guidelines 

Levels for hazardous chemicals. National 

Academy of Sciences, National Research 

Council (NRC), Committee on Toxicology, 

Subcommittee on Acute Exposure Guideline Levels. Washington, DC: National 

Academy Press, IBSN: 0-309-07553-X, 

http://www.epa.gov/sites/production/

files/2015-09/documents/sop_final_standing_operating_procedures_2001.pdf. 

NAS [2014]. Acute Exposure Guideline Levels (AEGLs) for selected airborne 

chemicals. Vol. 16. Methacrylonitrile (CAS 

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