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1

2

3

4

5 

6

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

8

9

10

11 FOR

12

13

14

15 CHLOROACETYL CHLORIDE

16

17

18

19 [CAS NO. 79-04-9] 

20

21

22

23

24

25

26 Department of Health and Human Services 

27 Centers for Disease Control and Prevention 

28 National Institute for Occupational Safety and Health 

29

30
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1 Disclaimer

2

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

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

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

6 responsible for the content of these Web sites. 

7

8 Ordering Information 

9

10 To receive this document or information about other occupational safety and health topics, contact NIOSH: 

11

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

13 TTY: 1-888-232-6348 

14 E-mail: cdcinfo@cdc.gov 

15 Or visit the NIOSH Web site: www.cdc.gov/niosh 

16

17 For a monthly update on news at NIOSH, subscribe to NIOSH eNews by visiting www.cdc.gov/niosh/eNews. 

18

19 DHHS (NIOSH) Publication No. XXX 

20

21
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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 chloroacetyl chloride (CAS # 79-04-9). 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 
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1 Centers for Disease Control and Prevention
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1 Table of Contents

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

3 ABBREVIATIONS .......................................................................................................................................................VI

4 GLOSSARY .................................................................................................................................................................VII

5 ACKNOWLEDGMENTS ..............................................................................................................................................X

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

7 1.1 IDLH VALUE FOR CHLOROACETYL CHLORIDE...........................................................................................................1

8 1.2 PURPOSE .....................................................................................................................................................................1

9 1.3 GENERAL SUBSTANCE INFORMATION .........................................................................................................................1

10 2.0 ANIMAL TOXICITY DATA............................................................................................................................. 5

11 3.0 HUMAN DATA ................................................................................................................................................. 9

12 4.0 SUMMARY........................................................................................................................................................ 9

13 REFERENCES............................................................................................................................................................. 10

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 HCl hydrochloric acid 

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 
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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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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 effects 

39 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 

25

26

27 
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1 1.0 Introduction 

2 1.1 IDLH Value for Chloroacetyl Chloride 

3

IDLH Value: 1.3 ppm (66 mg/m3 4 )

5

6 Basis for IDLH Value: The IDLH value for chloroacetyl chloride is based on potentially escape-impairing 

7 effects including clinical signs of severe ocular and respiratory irritation in rats exposed to 32 ppm for one hour 

8 [Dow 1986]. The equivalent 30-minute exposure duration value is 40 ppm. Applying a composite uncertainty 

9 factor of 30 to account for extrapolation from a potentially escape impairing effect in animals, animal to human 

10 differences and human variability, results in an IDLH value of 1.3 ppm. 

11

12 1.2 Purpose 

13

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

15 exposures to chloroacetyl chloride and (2) the rationale behind the Immediately Dangerous to Life or Health 

16 (IDLH) value for chloroacetyl chloride. IDLH values are developed based on the scientific rationale and logic 

17 outlined in the NIOSH Current Intelligence Bulletin (CIB) 66: Derivation of Immediately Dangerous to Life or 

18 Health (IDLH) values [NIOSH 2013]. As described in CIB 66, NIOSH performs in-depth literature searches to 

19 ensure that all relevant data from human and animal studies with acute exposures to the substance are identified. 

20 Information included in CIB 66 on the literature search includes pertinent databases, key terms, and guides for 

21 evaluating data quality and relevance for the establishment of an IDLH value. The information that is identified 

22 in the in-depth literature search is evaluated with general considerations that include description of studies (i.e., 

23 species, study protocol, exposure concentration and duration), health endpoint evaluated, and critical effect levels 

24 (e.g., NOAELs, LOAELs, LC50 values). For chloroacetyl chloride, the in-depth literature search was conducted 

25 through February 2014. 

26

27 1.3 General Substance Information 

28

29 Chemical: Chloroacetyl chloride 

30 CAS No: 79-04-9 

Synonyms: Chloroacetic acid chloride; Chloroacetic chloride; Monochloroacetyl chloride* 31

Chemical category: Substituted carboxylic acid halides; Organic chlorine compounds † 32
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1 Structural formula: 

2

3

4

5

6

7 Table 1 highlights selected physiochemical properties of chloroacetyl chloride relevant to IDLH conditions. Table 

8 2 provides alternative exposure guidelines for chloroacetyl chloride. Table 3 summarizes the Acute Exposure 

9 Guidelines Level (AEGL) values for chloroacetyl chloride.

10

11 Table 1: Physiochemical Properties of Chloroacetyl Chloride 

12

Property Value 

Molecular weight 112.94‡

Chemical formula C2H2Cl2O 

Description Colorless to yellow liquid 

Odor Pungent

Odor Threshold Strongly detectable at 0.140 ppm; 

barely detectable at 0.023 ppm; 

undetectable at 0.011 ppm,‡

UEL Not available§

LEL Not available§

Vapor pressure 25.2 mmHg at 25°C (77°F)‡

Flash point Non-combustible†

Ignition temperature Non-combustible†

Solubility Violent decomposition in water†

Abbreviation: oC – Celsius; o 13 F – Fahrenheit; mmHg – millimeter mercury; LEL – lower explosive limit; UEL – upper explosive limit * 14 NLM [2014] 

† 15 IFA [2014] 

‡ 16 HSDB [2014] 

§ 17 OSHA [2014]

Cl

Cl

O
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1 Table 2: Alternative Exposure Guidelines for Chloroacetyl Chloride 

2

Organization Value 

Original (SCP) IDLH value [NIOSH 2014] None 

NIOSH REL [2014] 0.05 ppm (0.23 mg/m3), TWA 

OSHA PEL [2014] 0.05 ppm (0.23 mg/m3

), TWA 8-hour 

ACGIH TLV [2014] 0.05 ppm (0.23 mg/m3

), TWA 

0.15 ppm (0.69 mg/m3) STEL

AIHA ERPG [2010] ERPG-1: 0.05 ppm 

ERPG-2: 0.5 ppm 

ERPG-3: 10 ppm 

AIHA WEEL [2010] Not available 

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

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

5 Institute for Occupational Safety and Health; OSHA – Occupational Safety and Health Administration; PEL – permissible exposure limit; 

6 REL – recommended exposure limit; SCP – Standards Completion Program; STEL – short-term exposure limit; TWA – time-weighted 

7 average; WEEL – workplace environmental exposure level 

8 

9
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1 Table 3: AEGL Values for Chloroacetyl Chloride 

2

Classification 10-min 30-min 1-hour 4-hour 8-hour Endpoint [AEGL-1 0.04 ppm 

0.19 mg/m3

0.04 ppm 0.19 mg/m3

0.040 ppm 0.19 mg/m3

0.04 ppm 0.19 mg/m3

0.04 ppm 0.19 mg/m3

NOEL for rats [Dow 

AEGL-2 2.9 ppm 

13.0 mg/m3

2.0 ppm 9.2 mg/m3

1.6 ppm 7.4 mg/m3

0.40ppm 1.8 mg/m3

0.20 ppm 0.92 mg/m3

NOEL for escape due in rats [Dow 

AEGL-3 95.0 ppm 

440.0 mg/m3

66.0 ppm 300.0 mg/m3

52.0 ppm 240.0 mg/m3

13.0 ppm 60.0 mg/m3

6.5 ppm 30.0 mg/m3

Threshold male rats [D

Abbreviation: AEGL – acute exposure guideline levels; mg/m3 3 – milligrams per cubic meter; min – minute; ppm – parts per million * 4 References: NAS [2007] 
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1 2.0 Animal Toxicity Data 

2

3 Chloroacetyl chloride decomposes in water to produce chloroacetic acid and hydrochloric acid (HCl), releasing 

4 heat in the process. Both chloroacetyl chloride and its hydrolysis products are irritants. Several modern studies 

5 [Dow 1982, 1986] reported analytical concentrations substantially lower than nominal concentrations (analytical 

6 concentrations about 25-50% of nominal). This difference has been attributed to both hydrolysis and incomplete 

7 volatilization of the test chemical. Since the total concentration of irritant chemicals in the air (including HCl) 

8 may have been higher than the analytical concentration of chloroacetyl chloride, use of the analytical 

9 concentration is a conservative approach. In light of the difference between nominal and analytical 

10 concentrations, the true concentrations (and associated LC50 values) in some of the older acute studies may have 

11 been lower than the reported nominal concentrations. 

12

13 In a static-exposure study, Carpenter et al. [1949] reported an approximate 4-hour LC50 value of 1,000 ppm in 

14 rats. No further experimental results were provided. Younger Labs [1969] exposed rats to “concentrated” 

15 chloroacetyl chloride; all died within two hours. The exposure concentration was not specified, although 

16 information suggested a saturated atmosphere (25,000 ppm at 20°C) [AIHA 2000]. Immediately upon exposure, 

17 the rats showed signs of irritation including pawing at the face and mouth, and tightly shut eyes. Within 10 

18 minutes, rats had reddened eyes with nasal and salivary excretion and gasping, and within 30 minutes they had 

19 opaque corneas, and death occurred after 90 (3/4 rats) or 120 (4/4) minutes. Severely hemorrhaged lungs were 

20 seen at necropsy [Younger Labs 1969]. 

21

22 Studies conducted by Dow Chemical Company in rats [Dow 1986] provide the most informative data for deriving 

23 the IDLH value. F344 rats were exposed whole-body to 32, 208, 522, or 747 ppm chloroacetyl chloride for 1 

24 hour, followed by observation for 14 days. Clinical signs observed during exposure included squinting and 

25 lacrimation at all concentrations (32 to 747 ppm), and shallow or labored breathing at 208 ppm and higher. 

26 Stress-related clinical signs were also observed at the higher concentrations; these included lethargy (≥208 ppm), 

27 salivation, and stained eyes and face. Gross pathological examination of the rats that died during the 2-week post 

28 exposure period showed lung and nasal tissue congestion. Death occurred only at 747 ppm, in 5/6 males and 1/6 

29 females, yielding an LC50 value of 645 ppm for males. The LC50 value for females could not be calculated, but 

30 was greater than 747 ppm. The effects at 32 ppm were considered potentially escape impairing. Results in mice 

31 and guinea pigs [Herzog 1959] support the determination that respiratory tract irritation is the key effect from 

32 exposure to chloroacetyl chloride, but the results are limited by the use of a static exposure protocol and the 
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1 absence of monitoring of analytical concentrations. Results from a 2-minute exposure study by Herzog [1959] 

2 support the conclusion that the onset of irritation is rapid. 

3

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

5 chloroacetyl chloride. Table 5 provides non-lethal data reported in animal studies with 30-minute equivalent 

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

7 LC, BMCL, NOAEL, LOAEL), adjusted 30-minute concentration, and the justification for the composite 

8 uncertainty factors applied to calculate the derived values. 

9 
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1 Table 4: Lethal Concentration Data for Chloroacetyl Chloride2

Reference Species 

(sex) 

LC50

(ppm) 

LCLo

(ppm) 

Time (min) 

Adjusted 30-min Concentration* (ppm) 

Composite Uncertainty Factor 

Derived Value (ppm)†

Herzog [1959] Mouse 1,066 -- 120 1,692 30‡ 56 Dow [1986] Rat 

(female) 

-- 747 60 941 10± 94 

Dow [1986] Rat 

(male) 

645 -- 60 813 30‡ 27 

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-minute concentration divided by the composite uncertainty factor. ‡ 10 Composite uncertainty factor to account for adjustment of LC50 values to LC01 values, use of lethal concentration threshold in animals, interspecies differe± 11 Composite uncertainty factor to account for lethal concentration threshold in animals, interspecies differences and human variability. 

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1 Table 5: Non-lethal Concentration Data for Chloroacetyl Chloride2

Reference Species 

(reference) 

NOAEL (ppm) 

LOAEL (ppm) 

Time (min) 

Adjusted 30-min Concentration* (ppm) 

Composite Uncertainty Factor 

Derived Value (ppm)†

Dow [1986] + Rat -- 32 60 40 30± 1.3 

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

* 5 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 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-minute concentration divided by the composite uncertainty factor. + 8 Identified study is the primary basis of the IDLH value for chloroacetyl chloride. ± 9 Composite uncertainty factor assigned to account for adjusting from a LOAEL to NOAEL, interspecies differences, human variability and extrapolation to 
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Health. It does not represent and should not be construed to represent any agency determination or policy. 

1 3.0 Human Data 

2

3 No reports of human deaths resulting from inhalation of chloroacetyl chloride were located. Exposure for an 

4 undefined time period (likely a few minutes) to an air concentration of 0.011 ppm chloroacetyl chloride was 

5 undetectable by odor; 0.023 ppm was “barely detectable,” and 0.14 ppm was considered a “strong” odor to an 

6 industrial hygienist [Dow 1988a]. Ocular irritation was not experienced at these concentrations, but 0.91 ppm 

7 was painful to the eyes and caused lacrimation [Dow 1988a]. This study is not appropriate as the basis for an 

8 IDLH value because insufficient information was provided about the exposure conditions, but the study does 

9 provide information on the range of exposure levels that are irritating. 

10 

11 The medical department of a chemical company reported that six workers who received “mild” inhalation 

12 exposures of chloroacetyl chloride (exposures not stated) experienced dyspnea and cough, and that three workers 

13 that received “moderate” inhalation exposures had cyanosis and cough [Dow 1988b].

14 4.0 Summary 

15

16 Available human and animal data demonstrated the ability of chloroacetyl chloride to act as a potent irritant, 

17 causing ocular and respiratory tract irritation, respiratory tract pathology and death depending on the exposure 

18 concentration and duration. Concentrations that induce potentially escape-impairing and significant irritant effects 

19 appear to be well below the estimated LC50 values summarized in Table 4. Studies reporting non-lethal effects, 

20 such as Dow [1988a], provide evidence that painful eye irritation and lacrimation occurred in humans exposed to 

21 0.91 ppm for an undisclosed duration. Dow [1986] reported significant irritation at 32 ppm as a LOAEL in rats. 

22 Taking into account the potential for significant irritant effects at concentrations well below reported LC50 values, 

23 the LOAEL of 32 ppm in rats is an appropriate basis for deriving the IDLH value. Duration adjustment to a 30-

24 minute equivalent concentration yields a concentration of 40 ppm. Application of a composite uncertainty factor 

25 to account for extrapolation from a potentially escape-impairing effect in animals, animal to human differences 

26 and human variability results in an IDLH value for chloroacetyl chloride of 1.3 ppm. This value is expected to 

27 protect against both lethality and severe ocular and respiratory irritation that might impair escape. 
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Health. It does not represent and should not be construed to represent any agency determination or policy. 

1 References 

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3 ACGIH (American Conference of Governmental Industrial Hygienists) [2014]. Annual TLVs® (Threshold Limit 

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18 (sanitized). Study report written by Henck JW, Nitschke KD, Jersey GC, et al., issued 6/28/82. Midland, MI: 

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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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