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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 DIKETENE

16

17

18 [CAS NO. 674-82-8] 

19

20

21

22

23

24

25 Department of Health and Human Services 

26 Centers for Disease Control and Prevention 

27 National Institute for Occupational Safety and Health 

28

29
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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 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 diketene (CAS # 674-82-8). The scientific 

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

30 transparency and scientific credibility. 

31

32 John Howard, M.D. 

33 Director 

34 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 .............................................................................................................................................XI

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

7 1.1 OVERVIEW OF THE IDLH VALUE FOR DIKETENE .....................................................................................................................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 ................................................................................................................................................. 6

12 4.0 SUMMARY........................................................................................................................................................ 6

13 5.0 REFERENCES......................................................................................................................................................... 7

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 IDLH immediately dangerous to life or health 

12 kPa kilopascal 

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

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

3 detailed understanding on a molecular level. 

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

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

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

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

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

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

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

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

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

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

14

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

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

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

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

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

20 half) decrease in the respiratory rate. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

36

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

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

39 further modification based on the overall database. 
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1 Workplace Environmental Exposure Levels (WEELs): Exposure levels developed by the American Industrial 

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

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

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

20 Science, College of Public Health, Ohio State University 

21

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

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

24 University 

25
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1 1.0		 Introduction		

2 1.1		 Overview of the IDLH Value for Diketene

3

4 IDLH Value: 7.6 ppm 

5

6 Basis for IDLH Value: The IDLH value for diketene is based on the rat BMCL05 of 181 ppm for lethality in a 1-

7 hour exposure [Katz 1987]. The duration adjusted BMCL05 for a 30-minute exposure is 228 ppm. A composite 

8 uncertainty factor of 30 was applied to account for extrapolation from a lethal concentration threshold in animals, 

9 animal to human differences, human variability, and database uncertainties, resulting in an IDLH value of 7.6 

10 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 diketene and (2) the rationale behind the Immediately Dangerous to Life or Health (IDLH) value for 

16 diketene. IDLH values are developed based on the scientific rationale and logic outlined in the NIOSH Current 

17 Intelligence Bulletin (CIB) 66: Derivation of Immediately Dangerous to Life or Health (IDLH) values [NIOSH 

18 2013]. As described in CIB 66, NIOSH performs in-depth literature searches to ensure that all relevant data from 

19 human and animal studies with acute exposures to the substance are identified. Information included in CIB 66 on 

20 the literature search includes pertinent databases, key terms, and guides for evaluating data quality and relevance 

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

22 evaluated with general considerations that include description of studies (i.e., species, study protocol, exposure 

23 concentration and duration), health endpoint evaluated, and critical effect levels (e.g., NOAELs, LOAELs, LC50

24 values). For diketene, the in-depth literature search was conducted through February 2014. 

25 1.3 General Substance Information		

26

27 Chemical: Diketene 

28 CAS No: 674-82-8 

Synonyms: Acetyl ketene; 4-Methylene-2-oxetanone; But-3-en-3-olide; Dimer ketene* 29

Chemical category: Lactones† 30
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1

2 Structural formula: 

3

4

5

6

7 Table 1 highlights selected physiochemical properties of diketene relevant to IDLH conditions. Table 2 provides 

8 alternative exposure guidelines for diketene. Table 3 summarizes the Acute Exposure Guidelines Level (AEGL) 

9 values for diketene. 

10

11 Table 1: Physiochemical Properties of Diketene 

12

Property Value 

Molecular weight 84.04‡

Chemical formula C4H4O2

Description Colorless to light-colored liquid 

Odor Pungent

Odor Threshold Not available 

UEL 11.7%†

LEL 2%†

Vapor pressure 1.07 kPa at 20°C (68°F)‡

Flash point 34°C (93.2°F)‡

Ignition temperature 275°C (527°F)†

Solubility Hydrolysis†

13 Abbreviation: °C – Celsius; °F – Fahrenheit; kPa – kilopascal; LEL – lower explosive limit; UEL – upper explosive limit * 14 NLM [2014] 

† 15 IFA [2014] 

‡ 16 HSDB [2014] 

17

18 Table 2: Alternative Exposure Guidelines for Diketene 

19

Organization Value 

Original (SCP) IDLH value None 

NIOSH REL Not available 

OSHA PEL [2014] Not available 

ACGIH TLV [2014] Not available 

AIHA ERPG [2010] ERPG-1: 1 ppm; ERPG-2: 5 ppm; ERPG-3: 20 ppm 

AIHA WEEL [2010] Not available 

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

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

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

23 REL – recommended exposure limit; SCP – Standard Completion Program; WEEL – workplace environmental exposure level 

O

O CH2
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1 Table 3: AEGL Values for Diketene 

2

Classification 10-min 30-min 1-hour 4-hour 8-hour Endpoint [AEGL-1 NR NR NR NR NR InsufficienAEGL-2 11 ppm 

38.0 mg/m3

7.7 ppm 26.0 mg/m3

6.0 ppm 21.0 mg/m3

1.5 ppm 5.2 mg/m3

0.77 ppm 2.6 mg/m3

AEGL-3 rfactor of 3 

AEGL-3 33.0 ppm 

110.0 mg/m3

23.0 ppm 79.0 mg/m3

18.0 ppm 62.0 mg/m3

4.5 ppm 15.0 mg/m3

2.3 ppm 7.9 mg/m3

BMCL05 f[Katz 198

Abbreviation: AEGL – acute exposure guideline levels; mg/m3 3 – milligrams per cubic meter; min – minute; NR – not recommended due to insufficient da* 4 References: NAS [2008]
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1 2.0 Animal Toxicity Data 

2

3 The available acute lethality database for diketene is limited to one rat study [Katz 1987] and one multi-species 

4 study [Wooster et al. 1947]. Katz [1987] exposed rats to 0, 250, 500, or 750 ppm diketene for one hour with a 14-

5 day post-exposure period. Clinical signs providing evidence of severe irritation included excessive tearing and 

6 gasping at all exposure levels, and porphyrin discharge from the nose at the two highest concentrations. No gross 

7 lesions were identified during necropsy. Mortality occurred at all concentrations except 250 ppm. Modeling of the 

8 mortality responses yielded an LC50 of 612 ppm. The lethality thresholds were estimated using benchmark 

9 concentration modeling, resulting in a BMCL05 (lower bound estimate of the concentration associated with a 

10 benchmark response of 5%) of 181 ppm for lethality. The 30-minute duration adjusted equivalent value of the 

11 BMCL05 is 228 ppm. 

12

13 Wooster et al. [1947] exposed mice to 194, 580, or 870 ppm diketene in an acetone solvent for 10 minutes with a 

14 15-day post-exposure period. Clinical signs were not reported. Pathological examination revealed proteinaceous 

15 edematous fluid in the alveoli and in the perivascular connective tissue of the bronchi. Only the highest 

16 concentration (870 ppm) resulted in mortality, one mouse died. Wooster et al. [1947] also exposed guinea pigs to 

17 194 ppm diketene for 10 minutes with a 15-day post-exposure observation period. No clinical signs were 

18 reported. The authors implied that the gross pathology findings indicated pulmonary edema as the cause of death. 

19 All guinea pigs in 194 ppm group died. Wooster et al. [1947] also exposed rats and rabbits to 194 ppm diketene 

20 for 10 minutes. No lethality, clinical signs, or gross pathology findings were noted. 

21

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

23 diketene. Information in these tables includes species of test animals, toxicological metrics (i.e., LC, NOAEL, 

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

25 calculate the derived values. 

26
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1 Table 4: Lethal Concentration Data for Diketene2

Reference Species 

(sex) 

LC50

(ppm) 

Other lethality concentration (ppm) 

Time (min) 

Adjusted 30-min Concentration*

(ppm) 

CUF

Katz [1987] Rats (male and female) 612 -- 60 771 3Katz [1987] Rats 370^ 60 466 3

Katz [1987] Rats 181‡ 60 228 3

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 est

8 available, therefore the 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, inte

11 human variability.

^ 12 LC10+ 13 Composite uncertainty factor to account for adjustment from a lethal concentration threshold in animals, interspecies differences, human v

14 uncertainties. 

‡ 15 Lower bound estimate of the concentration associated with a benchmark response of 5% for lethality. 

161718
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1 3.0 Human Data 

2 Only very limited information on human effects and effect levels was available. Occupational exposure to 

3 diketene was reported to cause mild irritation to the conjunctiva and mucosa of the nose and throat at a 

4 concentration of 0.58 ppm for one minute [Fel’dman 1967]. These studies were not appropriate for an IDLH 

5 value derivation due to the very short duration and limited details available.

6 4.0 Summary 

7 The IDLH value for diketene is based on the rat BMCL05 of 181 ppm for lethality in a 1-hour exposure [Katz 

8 1987]. The duration adjusted BMCL05 for a 30-minute exposure is 228 ppm. Application of composite 

9 uncertainty factor of 30 to account for extrapolation from a lethal concentration threshold in animals, animal to 

10 human differences, human variability, and database uncertainties, including uncertainty regarding the threshold 

11 for severe irritation, yielded an IDLH value of 7.6 ppm. 
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1 5.0 References 

2

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

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46
External Review Draft 

May 2015 

8

This information is distributed solely for the purpose of pre-dissemination peer review under applicable 

information 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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