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1

2

3

4

5

6

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

8

9

10 FOR 

11

12

13

14

15 1,1-DICHLORO-1-FLUOROETHANE (HCFC-141B) 

16

17

18

19

20 [CAS No. 1717-00-6] 

21

22

23

24

25

26

27 Department of Health and Human Services 

28 Centers for Disease Control and Prevention 

29 National Institute for Occupational Safety and Health 

30

31
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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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1 Foreword 

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

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

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

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

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

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

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

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

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

11 transportation incidents or other uncontrolled-release scenarios). 

12

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

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

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

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

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

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

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

20 Preparedness Plans. 

21

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

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

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

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

26 scientifically credible IDLH values using available data resources. 

27

28 The purpose of this technical report is to present the IDLH value for HCFC-141B (CAS # 1717-00-6). The 

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

30 ensure transparency and scientific credibility. 

31

32 John Howard, M.D. 

33 Director 

34 National Institute for Occupational Safety and Health 

35 Centers for Disease Control and Prevention
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1 Table of Contents 

2 FOREWORD ................................................................................................................................................................ III

3 ABBREVIATIONS ........................................................................................................................................................V

4 GLOSSARY ..................................................................................................................................................................VI

5 ACKNOWLEDGMENTS .............................................................................................................................................IX

6 1.0 INTRODUCTION.............................................................................................................................................. 1

7 1.1 IDLH VALUE FOR 1,1-DICHLORO-1-FLUOROETHANE (HCFC-141B)..........................................................................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 5.0 REFERENCES......................................................................................................................................................... 9

14

15

16

17

18
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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 CAS chemical abstract service 

10 ERPG Emergency Response Planning Guidelines 

11 HCFC-141b 1,1-dichloro-1-fluoroethane 

12 IDLH immediately dangerous to life or health 

13 LC50 median lethal concentration 

14 LCLo lowest concentration of a chemical that caused death in humans or animals 

15 LEL lower explosive limit 

16 LOAEL lowest observed adverse effect level 

mg/m3 17 milligram(s) per cubic meter 

18 NAC National Advisory Committee 

19 NAS National Academy of Sciences 

20 NIOSH National Institute for Occupational Safety and Health 

21 NOAEL no observed adverse effect level 

22 OSHA Occupational Safety and Health Administration 

23 PEL permissible exposure limit 

24 ppm parts per million 

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

26 rate 

27 REL recommended exposure limit 

28 SCP Standard Completion Program 

29 STEL short term exposure limit 

30 TLV threshold limit value 

31 TWA time weighted average 

32 UEL upper explosive limit 

33 WEEL workplace environmental exposure level 

34 μg/kg microgram(s) per kilogram of body weight
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1 

2 Glossary 

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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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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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 

39 effects related to occupational chemical exposures expressed as a TWA or ceiling limit.
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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 Mary A. Fox, Ph.D., Assistant Professor; Co-Director, Risk Sciences and Public Policy Institute; 

19 Department of Health Policy and Management, Bloomberg School of Public Health, Johns Hopkins 

20 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 
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1 1.0 Introduction 

2 1.1 IDLH Value for 1,1-Dichloro-1-fluoroethane (HCFC-141b) 

3

IDLH Value: 1,667 ppm (7,974 mg/m3 4 )

5

6 Basis for IDLH Value: Cardiac sensitization is the most sensitive indicator of toxicity and is an appropriate non7 lethal endpoint to serve as the basis for the IDLH value for 1,1-dichloro-1-fluoroethane (HFCF-141b), This effect 

8 was reported in monkeys exposed to 5,000 ppm for 10 minutes [Hardy et al. 1989] and in a dog exposed to 5,200 

9 ppm for 10 minutes [Mullin 1977]. No time scaling factor was applied, based on data that the threshold for this 

10 effect is constant for durations longer than 5-10 minutes. Using the concentration of 5,000 ppm reported in Hardy 

11 et al. [1989] as the point of departure and applying a composite uncertainty factor of 3 to account for extrapolation 

12 from a severe effect threshold in animals, animal to human differences and human variability, results in an IDLH 

13 value for HCFC-141b of 1,667 ppm. 

14

15 1.2 Purpose 

16

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

18 exposures to HCFC-141b and (2) the rationale behind the Immediately Dangerous to Life or Health (IDLH) value 

19 for HCFC-141b. IDLH values are developed based on the scientific rationale and logic outlined in the NIOSH 

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

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

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

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

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

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

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

27 LOAELs, LC50 values). For HCFC-141b, the in-depth literature search was conducted through February 2014. 

28 1.3 General Substance Information 

29

30 Chemical: 1,1-Dichloro-1-fluoroethane 

31 CAS No: 1717-00-6 

Synonyms: HCFC-141b; Freon-141; CFC 141b* 32
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1 Chemical category: Aliphatic, saturated, halogenated hydrocarbons; Organic chlorine compounds; Organic 

fluorine compounds† 2

3 Structural formula: 

4

5

6

7

8 Table 1 highlights selected physiochemical properties of HCFC-141b relevant to IDLH conditions. Table 2 

9 provides alternative exposure guidelines for HFC-141b. Table 3 summarizes the Acute Exposure Guidelines 

10 Level (AEGL) values for HFC-141b. 

11

12 Table 1: Physiochemical Properties of HCFC-141b 

13

Property Value 

Molecular weight 116.95‡

Chemical formula C2H3Cl2F 

Description Colorless liquid 

Odor Weak ethereal odor

Odor Threshold 250 ppm+

 

UEL 17.7%†

LEL 5.6%†

Vapor pressure 600 mmHg at 25°C (77°F)‡

Flash point Not available 

Ignition temperature Not available 

Solubility Slightly soluble in water†

Abbreviation: oC – Celsius; o 14 F – Fahrenheit; mmHg – millimeter mercury; LEL – lower explosive limit; UEL – upper explosive limit + 15 Hardy et al. [1989] * 16 NLM [2014] 

† 17 IFA [2014] 

‡ 18 HSDB [2014] 

19

20 Table 2: Alternative Exposure Guidelines for HCFC-141b 

21

Organization Value 

Original (SCP) IDLH value [NIOSH 2014] None 

NIOSH REL [NIOSH 2014] Not available 

OSHA PEL Not available 

ACGIH TLV [2014] Not available 

AIHA ERPG [2010] Not available 

AIHA WEEL [2010] 500 ppm, 8 hr TWA 

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

23 Association; ERPG – Emergency Response Preparedness Guidelines; IDLH – immediately dangerous to life or health; NIOSH – National 

24 Institute for Occupational Safety and Health; OSHA – Occupational Safety and Health Program; PEL – permissible exposure limit; REL – 

25 recommended exposure limit; SCP – Standards Completion Program; TWA – time-weighted average; WEEL – workplace environmental 

26 exposure level 

Cl

F CH3

Cl
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1 Table 3: AEGL Values for HCFC-141b 

2

Classification 10-min 30-min 1-hour 4-hour 8-hour AEGL-1 1,000 ppm 

(4,850 mg/m3) 

1,000 ppm (4,850 mg/m3) 

1,000 ppm (4,850 mg/m3) 

1,000 ppm (4,850 mg/m3) 

1,000 ppm 4,850 mg/m3) 

No effect in [Utell et al. 

AEGL-2 1,700 ppm 

(8,245 mg/m3) 

1,700 ppm (8,245 mg/m3) 

1,700 ppm (8,245 mg/m3) 

1,700 ppm (8,245 mg/m3) 

1,700 ppm 8,245 mg/m3) 

Threshold foarrhythmia i[Mullin 197

AEGL-3 3,000 ppm 

(14,550 mg/m3) 

3,000 ppm (14,550 mg/m3) 

3,000 ppm (14,550 mg/m3) 

3,000 ppm (14,550 mg/m3) 

3,000 ppm (14,550 mg/m3) 

Threshold focardiac resp[Hardy et al

Abbreviation: AEGL – acute exposure guideline levels; mg/m3 3 – milligrams per cubic meter; min – minute; ppm – parts per million * 4 References: NAS [2002] 

5
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1 2.0 Animal Toxicity Data 

2 Acute inhalation toxicity tests were performed in rats and mice. A 4-hour rat LC50 value was reported for male 

3 and female rats at 58,931 and 64,991 ppm, respectively, with a combined LC50 of 61,647 ppm [de Rooij 1989; 

4 Brock et al. 1995]. Brock et al. [1995] also reported a 6-hour LC50 value of 56,700 ppm in rats. Both studies 

5 reported reduced motor activity, shallow breathing with rapid respiration, and anesthesia at concentrations greater 

6 than 29,000 ppm; tremors, incoordination, and convulsions were noted in some animals above 50,000 ppm. 

7

8 A 30-minute LC50 value of 100,000 ppm in mice was reported by Davies et al. [1976] with effects including 

9 narcosis. In a second study in mice [Vlachos 1988], the authors reported a 60% mortality in mice exposed to 

10 80,000 ppm for 6 hours. No clinical signs of exposure were observed up to 30,000 ppm. Lethargy and tremors 

11 were observed at 41,000 ppm, and narcosis occurred within 15 minutes at 80,000 ppm. Deaths were attributed to 

12 deep anesthesia. 

13

14 Cardiac sensitization tests were conducted in rats, dogs and monkeys. A response in this cardiac sensitization 

15 assay is considered a sensitive measure of a severe effect. Arrhythmia in these cases is not produced by HCFC16 141b; rather, it is the result of the potentiation of endogenous epinephrine (adrenalin) by the chemical. NAS 

17 [2014] described an unpublished study in which Sprague-Dawley rats were exposed to 5,000, 10,000, or 20,000 

18 ppm of HCFC-141b for 30 minutes and administered 12 μg/kg epinephrine. NAS [2014] reported that marked 

19 arrhythmia was observed in 4/11 animals at 5,000 ppm. 

20

21 Mullin [1977] exposed dogs to 2,600, 5,200, 10,000, or 21,600 ppm for 5 minutes followed by an intravenous 

22 dose of 8 μg/kg epinephrine. Cardiac sensitization was induced in 1/10 dogs at 5,200 ppm; deaths occurred at 

23 higher concentrations. The authors also reported a no-effect level at 2,600 ppm. In a second cardiac sensitization 

24 study, dogs were exposed to 9,000, 12,000, 13,000, 14,000, 15,000, 18,000, 19,000, or 20,000 ppm for 5 minutes 

25 followed by challenge with 10 μg/kg of intravenous epinephrine [Hardy et al. 1989]. A marked cardiac response 

26 was reported in 1/2 dogs at 9,000 ppm, but there was no response in eight other trials at 9,000 – 13,000 ppm. The 

27 one dog exposed to 20,000 ppm and then challenged with epinephrine developed severe ventricular fibrillation 

28 and died. Monkeys were exposed to 0, 3,000, 5,000, or 10,000 ppm for 10 minutes [Hardy et al. 1989]. After 5 

29 minutes of exposures, the monkeys received epinephrine. No electrocardiogram effects were seen in the monkey 

30 exposed to 3,000 ppm, but the authors reported a marked cardiac response at 5,000 ppm. 

31
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1 Table 4 summarizes the LC data identified in animal studies and provides 30-minute equivalent derived values for 

2 HCFC-141B. Table 5 provides non-lethal data reported in animal studies with 30-minute equivalent derived 

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

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

5 applied to calculate the derived values. 
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1 Table 4: Lethal Concentration Data for HCFC-141b2

Reference Species LC50

(ppm) 

LCLo

(ppm) 

Time (min) 

Adjusted 30-min LC value* 

Composite Uncertainty Factor 

Derived Value (ppm)†

Davies et al. [1976] Mouse 100,000 -- 30 100,000 30‡ 3,333 Brock et al. [1995] Rat 56,700 -- 360 128,739 30‡ 4,291 Brock et al. [1995] Rat (M+F)± 61,647 -- 240 123,294 30‡ 4,101 

34 Abbreviation: LC – lethal concentration; LC50 – median lethal concentration; LCLo – lowest concentration of a chemical that caused death in humans or a5 per million 6

* For exposures other than 30 minutes the ten Berge et al. [1986] relationship is used for duration adjustment (Cn 7 x t = k); no empirically estimated n values 

8 default values were used, n = 3 for exposures greater than 30 minutes and n = 1 for exposures less than 30 minutes. 9 †The derived value is the result of the adjusted 30-min value divided by the composite uncertainty factor. The composite uncertainty factor used varies for 

10 and severity of the endpoint observed. 11 ‡Composite uncertainty factor to account for adjustment of LC50 values to LC01 values, use of lethal concentration threshold in animals, interspecies diffe

± 12 M+F – males and females combined 

131415
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1 Table 5: Non-lethal Concentration Data for HCFC-141b2

Reference Species NOAEL 

(ppm) 

LOAEL (ppm) 

Time (min) 

Adjusted 

30-min Concentration* 

Composite Uncertainty Factor 

Derived Value (ppm)†

Mullin [1977] Dog 5,200 -- 10 5,200‡ 3± 1,733 Hardy et al. [1989] Monkey 5,000 -- 10 5,000‡ 3± 1,667 

3 Abbreviation: NOAEL – no observed adverse effect level; min – minute; LOAEL – lowest observed adverse effect level; ppm – parts per million4

* For exposures other than 30 minutes the ten Berge et al. [1986] relationship is used for duration adjustment (Cn 5 x t = k); no empirically estimated n value

6 default values were used, n = 3 for exposures greater than 30 minutes and n = 1 for exposures less than 30 minutes. 7 †The derived value is the result of the adjusted 30-min value divided by the composite uncertainty factor. The composite uncertainty factor used varies for 8 and severity of the endpoint observed. 

‡ 9 The cardiac sensitization response is a concentration-dependent threshold effect; dogs exposed to similar chemicals for longer durations responded in a sim

10 adjustment was applied. 

± 11 Composite uncertainty factor assigned to account for extrapolation from a severe effect threshold in animals, animal to human differences and human vari
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quality guidelines. It has not been formally disseminated by the National Institute for Occupational Safety and 

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

1 3.0 Human Data 

2 Information regarding lethality in humans is limited to a single case report. Astier and Paraire [1997] reported a 

3 worker was found dead with a bluish-purple coloration and edema of the face inside a degreasing tank in which 

4 pure HCFC-141b was used as the degreasing solvent. The concentration and exposure duration were not reported. 

5 In an experimental study [Utell et al. 1997] eight volunteers were exposed to 0, 250, 500, or 1,000 ppm for 4 

6 hours with three 20 minute exercise periods. Endpoints evaluated included clinical chemistry, hematology, EKG, 

7 and spirometry. No effects were reported on these sensitive measures during exposures (aside from the expected 

8 response to exercise). In addition, two of the volunteers were exposed at 0 or 500 ppm for 6 hours and one 

9 volunteer was exposed to 1,000 ppm for 6 hours, and performed computerized neurobehavioral testing during the 

10 last 2 hours of exposure. No effects were seen.

11 4.0 Summary 

12 Limited human data are available on HCFC-141b. Multiple animal studies revealed the onset of cardiac 

13 sensitization to HCFC-141b. This non-lethal and potentially irreversible effect is the basis of the IDLH value. 

14 Monkeys exposed to 5,000 ppm for 10 minutes [Hardy et al. 1989] and a dog exposed to 5,200 ppm for 10 

15 minutes [Mullin 1977] both demonstrated cardiac responses. NAS [2002] determined that the cardiac 

16 sensitization response is a concentration-dependent threshold effect; animals exposed to similar chemicals for 

17 longer durations responded in a similar manner. Therefore, a duration adjustment for time scaling is not applied, 

18 thus the reported exposure concentration is used instead of a 30-minute equivalent. The 5,000 ppm concentration 

19 reported by Hardy et al. [1989] is used as the point of departure and basis of the IDLH value for HCFC-141b. 

20 Application of an uncertainty factor of 3 to account for extrapolation given consideration of animal to human 

21 differences and human variability results in an IDLH value of 1,667 ppm. 

22
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1 5.0 References 

2

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quality guidelines. It has not been formally disseminated by the National Institute for Occupational Safety and 

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

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