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i

1

2

3

4

5

6

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

8

9

10

11 FOR

12

13

14

15 HEXAFLUOROACETONE (HFA) 

16

17

18

19 [CAS NO. 684-16-2] 

20

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 
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ii

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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iii

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 hexafluoroacetone (CAS # 684-16-2). . 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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iv

1 Table of Contents

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

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

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

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

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

7 1.1 OVERVIEW OF THE IDLH VALUE FOR HEXAFLUOROACETONE ...................................................................................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 5.0 REFERENCES....................................................................................................................................................... 10

14

15

16

17

18
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v

1 Abbreviations 

2

3 ACGIH American Conference of Governmental Industrial Hygienists 

4 AEGL Acute Exposure Guideline Levels 

5 AIHA American Industrial Hygiene Association 

6 BMC benchmark concentration 

7 BMCL benchmark concentration lower confidence limit 

8 C ceiling 

9 CAS chemical abstract service 

10 ERPG Emergency Response Planning Guidelines 

11 HFA hexafluoroacetone 

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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vi

1 Glossary

2

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

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

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

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

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

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

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

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

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

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

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

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

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

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

18 assessments [USEPA 2014]. 

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

20 to 96 hours. 

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

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

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

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

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

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

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

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

29 Bolus Exposure: A single, relatively large dose. 

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

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

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

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

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

35 [USEPA 2014]. 

36

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

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

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

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

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

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

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

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

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

6 response to gross manifestations of clinical toxicity. 

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

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

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

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

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

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

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

14 specific exposure conditions. 

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

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

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

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

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

20 minute exposure duration. 

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

22 the test animals. 

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

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

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

26 percentage of the test animals. 

27

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

29 the test animals; median lethal concentration. 

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

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

32 the presence of an ignition source. 

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

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

35 death. 

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

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

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

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

40 detailed understanding on a molecular level. 
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viii

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

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

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

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

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

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

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

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

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

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

11

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

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

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

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

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

17 half) decrease in the respiratory rate. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

33

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

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

36 further modification based on the overall database. 

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

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

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

1 Acknowledgments 

2

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

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

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

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

7

8 Education and Information Division 

9 Devin Baker, M.Ed. 

10 Charles L. Geraci, Ph.D. 

11 Thomas J. Lentz, Ph.D. 

12 Richard Niemeier, Ph.D. 

13 Chris Sofge, Ph.D. 

14

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

16 technical review of this report. 

17

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

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

20 Science, College of Public Health, Ohio State University 

21

22 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 
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1

1 1.0 Introduction 

2 1.1 Overview of the IDLH Value for Hexafluoroacetone 

3

IDLH Value: 9 ppm (61 mg/m3 4 )

5

6 Basis for IDLH Value: A rat LC50 value of 900 ppm for a 30-minute exposure period is the basis of the IDLH 

7 value for hexafluoroacetone [Borzelleca and Lester 1965], since it was the lowest value among studies with the 

8 most appropriate exposure duration. A composite uncertainty factor of 100 was applied to account for 

9 extrapolation from a lethal concentration in animals, animal to human differences, human variability and 

10 uncertainties in the database, including uncertainties about the potential for developmental toxicity from acute 

11 exposure, as well as the lack of data on female reproductive toxicity and functional measures of reproductive 

12 toxicity; resulting in a recommended IDLH value of 9 ppm. 

13

14 1.2 Purpose

15

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

17 exposures to hexafluoroacetone and (2) the rationale behind the Immediately Dangerous to Life or Health (IDLH) 

18 value for hexafluoroacetone. IDLH values are developed based on the scientific rationale and logic outlined in the 

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

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

21 relevant data from human and animal studies with acute exposures to the substance are identified. Information 

22 included in CIB 66 on the literature search includes pertinent databases, key terms, and guides for evaluating data 

23 quality and relevance for the establishment of an IDLH value. The information that is identified in the in-depth 

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

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

26 NOAELs, LOAELs, LC50 values). For hexafluoroacetone, the in-depth literature search was conducted through 

27 February 2014. 

28 1.3 General Substance Information 

29

30 Chemical: Hexafluoroacetone 

31 CAS No: 684-16-2 
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2

Synonyms: HFA; 1,1,1,3,3,3-Hexafluoro-2-propanone; Hexafluoro-2-propanone; Perfluoroacetone* 1

Chemical category: Substituted ketones oxo compounds; Organic fluorine compounds; Organic gases† 2

3

4 Structural formula: 

5

6

7

8

9 Table 1 highlights selected physiochemical properties of hexafluoroacetone relevant to IDLH conditions. Table 2 

10 provides alternative exposure guidelines for hexafluoroacetone. Table 3 summarizes the Acute Exposure 

11 Guidelines Level (AEGL) values for hexafluoroacetone.

12

13 Table 1: Physiochemical Properties of Hexafluoroacetone 

14

Property Value 

Molecular weight 166.03‡

Chemical formula C3F6O

Description Colorless gas 

Odor Disagreeable, musty

Odor Threshold Not available 

UEL Not applicable*

LEL Not applicable*

Vapor pressure 5.0 mmHg at 25°C (77°F)‡

Flash point Noncombustible†

Ignition temperature Noncombustible†

Solubility Soluble in water; hydrolyses†

15 Abbreviation: °C – Celsius; °F – Fahrenheit; mmHg – millimeter mercury; LEL – lower explosive limit; UEL – upper explosive limit * 16 OSHA [2014] 

† 17 IFA [2014] 

‡ 18 HSDB [2014]

19

20

21

22

23

24

25

26

27

28

F F

F

F

F

F

O
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3

1 Table 2: Alternative Exposure Guidelines for Hexafluoroacetone 

2

Organization Value 

Original (SCP) IDLH value None 

NIOSH REL Not available 

OSHA PEL [2014] 0.1 ppm TWA [skin] 

ACGIH TLV [2014] Not available 

AIHA ERPG [2010] ERPG-1: not derived; ERPG-2: 1 ppm; ERPG-3: 50 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; WEEL – workplace environmental exposure level 
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1 Table 3: AEGL Values for Hexafluoroacetone 

2

Classification 10-min 30-min 1-hour 4-hour 8-hour Endpoint [refAEGL-1 NR NR NR NR NR Insufficient daAEGL-2 0.40 ppm 

2.7 mg/m3

0.40 ppm 2.7 mg/m3

0.20 ppm 1.4 mg/m3

0.050 ppm 0.34 mg/m3

0.025 ppm 0.17 mg/m3

NOAEL for de[E. I. du Pont d

AEGL-3 160.0 ppm 

1,100.0 mg/m3

160.0 ppm 1,100.0 mg/m3

80.0 ppm 540.0 mg/m3

20.0 ppm 140.0 mg/m3

10.0 ppm 68.0 mg/m3

Lethality thres

data [E. I. du Pont d

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 [2012] 
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5

1 2.0 Animal Toxicity Data 

2

3 Several acute inhalation studies were identified for hexafluoroacetone. Borzelleca and Lester [1965] exposed rats 

4 to a series of concentrations (range not reported) for 0.5, 3 or 6 hours. LC50 values of 900 ppm and 275 ppm were 

5 reported for 30-minute and 3-hour exposures, respectively; 6-hour values were not reported. Minor to no lung 

6 effects were reported for all the concentrations. The author also reported that postmortem exam revealed 

7 pulmonary hemorrhage and edema in dogs exposed to 5,000 and 10,000 ppm for either 30 or 45 minutes. E.I. du 

8 Pont de Nemours & Co. [1965] found that exposure to 3,600 ppm for 30 minutes was not lethal to rats (0/4 died), 

9 but 3/4 rats died after exposure to 4,800 ppm for 30 minutes. Rats in all groups down to the lowest concentration 

10 of 2,400 ppm exhibited signs of irritation, including lacrimation, salivation, nasal discharge, and intermittent 

11 gasping. 

12

13 Acute exposure to hexafluoroacetone also causes testicular damage. Rats exposed to 100 ppm for 4 hours 

14 exhibited slight to moderate testicular damage [E.I. du Pont de Nemours & Co. 1962]. More severe damage, 

15 including aspermatogenesis and interstitial damage, were observed at 200 ppm and higher. E.I. du Pont de 

16 Nemours & Co. [1965] exposed rats to 200 ppm hexafluoroacetone for 4 hours, and sacrificed the rats at 7-57 

17 days post-exposure. The observed testicular degeneration and decreased testicular weight were only slowly (or 

18 partially) reversible. At 57 days, there was some recovery, but some spermatogenic tubules still contained no 

19 germinal cells. 

20

21 Effects of hexafluoroacetone appear to be systemically mediated, with pulmonary damage in rats occurring only 

22 at air concentrations exceeding minimal lethality levels. Contact irritation also occurs. Gillies and Lee [1983] 

23 suggested that the testicular effects of hexafluoroacetone are due to its alterations of lipid metabolism and the 

24 resulting inhibition of sterol synthesis. This hypothesized pathway for male reproductive effects suggests that 

25 hexafluoroacetone may also affect female reproductive hormones, and thus female reproductive function, but no 

26 data investigating this hypothesis were located. 

27

28 These possibly hormonally-mediated effects may also be related to the developmental toxicity of 

29 hexafluoroacetone. Exposure of pregnant rats to 6.9 ppm for 6 hours/day on gestation days (GD) 7-16 resulted in 

30 increased resorptions, malformations, and variations [E.I. du Pont de Nemours & Co. 1969]. Exposure to 1 ppm 

31 in the same study resulted in increased variations (no statistical test information available) and decreased body 

32 weight, while the only effect in the mothers was increased liver weight. The study authors considered the fetal 
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6

1 effects to be more severe than the concurrent maternal effects. This repeated exposure study is not appropriate as 

2 the basis for the IDLH value, but it does raise the question of whether acute hexafluoroacetone exposure during a 

3 key developmental window could cause developmental effects. For a single 6-hour exposure period at the 

4 LOAEL for severe effects of 6.9 ppm from this study, the equivalent 30-minute duration-adjusted concentration is 

5 83 ppm. 

6

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

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

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

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

11 calculate the derived values. 
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1 Table 4: Lethal Concentration Data for Hexafluoroacetone

2

Reference Species 

(reference) 

LC50

(ppm) 

LCLo

(ppm) 

Time (min) 

Adjusted 30-min Concentration* (ppm) 

Composite Uncertainty Factor 

Borzelleca and Lester [1965] Dog 5,000‡ -- 45 5,724 100± E.I. du Pont de Nemours & Co. [1962] Rat 300§ -- 240 2,400 100± 

E.I. du Pont de Nemours & Co. [1965] Rat -- 3,600^ 30 3,600 30‡ 

Borzelleca and Lester [1965]+ Rat 900 -- 30 900 100± 

Borzelleca and Lester [1965] Rat 275 -- 180 1,650 100± 

34 Abbreviation: LC – lethal concentration; LC50 – median lethal concentration; LCLo – lowest concentration of a chemical that caused death in humans or a5 per million 67 *For exposures other than 30 minutes the ten Berge et al. [1986] relationship is used for duration adjustment (Cn x t = k); no empirically estimated n values 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 LC value divided by the composite uncertainty factor.‡ 10 1 of 2 dogs died ± 11 Composite uncertainty factor to account for the use of lethal concentration threshold in animals, interspecies differences, human variability 

12 database that focus on issues pertaining to developmental toxicity from acute exposure, absence of data on female reproductive toxicity and 13 reproductive toxicity. 

‡ 14 Composite uncertainty factor to account for the use of a lethal concentration threshold in animals, interspecies differences and human varia§ 15 2 of 4 rats died ^ 16 No lethality + 17 Identified study is the primary basis of the IDLH value for hexafluoroacetone. 

1819202122
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1 Table 5: Non-lethal Concentration Data for Hexafluoroacetone 

2

Reference Species NOAEL 

(ppm) 

LOAEL (ppm) 

Time (min) 

Adjusted 

30-min Concentration* 

Composite Uncertainty Factor 

Derived Value (ppm)†

E.I. du Pont de Nemours & Co. [1962a] rat 200 240 1,600 30^ 53 E.I. du Pont de Nemours & Co. [1962b] rat 100 240 800 30^ 2727 

E.I. du Pont de Nemours & Co. [1989] rat 6.9 360 82.8 10± 8 

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 adjusting from a LOAEL to NOAEL, severe effects, interspecies differences, human variability, and 

12 escape-impairing effects. 

± 13 Composite uncertainty factor assigned to account for adjusting from a LOAEL to NOAEL, interspecies differences and human variability.

141516
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9

1 3.0 Human Data 

2

3 There are no acute lethality data available for humans. Kutznetsova [1972] reported that exposure to 

4 hexafluoroacetone at 4 ppm is irritating to the respiratory tract, but specific descriptions were not provided on the 

5 exposure conditions that induce irritation or on the severity of the observed effects. 

6 4.0 Summary 

7

8 Among the acute lethality studies, the rat LC50 value of 900 ppm for a 30-minute exposure period [Borzelleca and 

9 Lester 1965] was chosen as the basis for the IDLH value for hexafluoroacetone since it was the lowest value 

10 among studies with the most appropriate exposure duration. A composite uncertainty factor of 100 was applied to 

11 account for extrapolation from a lethal concentration in animals, animal to human differences, human variability 

12 and uncertainties in the database, including uncertainties about the potential for developmental toxicity from acute 

13 exposure, as well as the lack of data on female reproductive toxicity and functional measures of reproductive 

14 toxicity; resulting in an IDLH value of 9 ppm. 

15

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

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

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

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

20 hexafluoroacetone is based on a NOAEL for developmental effects in rats [NAS 2012]. NIOSH based the IDLH 

21 value for hexafluoroacetone on lethality data from a rat study [Borzelleca and Lester 1965]. More precisely, the 

22 point of departure was a LC50 value of 900 ppm for a 30-minute exposure period. The use of differing studies and 

23 endpoints results in the order of magnitude different between the AEGL-2 and IDLH value. 
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10

1 5.0 References 

2

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

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13 Borzelleca JF, Lester D [1965]. Acute toxicity of some perhalogenated acetones. Toxicol Appl Pharmacol 7:592–

14 597. 

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16 E. I. du Pont de Nemours & Co. [1962]. Inhalation toxicity of hexafluoroacetone compound in rats. Newark, DE: 

17 E. I. du Pont de Nemours & Co., Haskell Laboratory for Toxicology and Industrial Hygiene. Haskell Laboratory 

18 report No. 46-62. Unpublished. 

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20 E. I. du Pont de Nemours & Co. [1965]. Inhalation studies on hexafluoroacetone. Part II. A. The lethality of short 

21 (<1 hr.). B. The persistence of tissue effects. Newark, DE: E. I. du Pont de Nemours & Co., Haskell Laboratory 

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27 HSDB (Hazardous Substances Data Bank) [2014]. Hexafluoroacetone (CAS No. 684-16-2) 

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33 Kutznestova EE [1972]. Hygienic standardization of perfluoroacetone dihydrate in air of working zones. Nauch. 

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36 NAS (National Academy of Science) [2001]. Standing operating procedures for developing Acute Exposure 

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46

47 NIOSH (National Institute for Occupational Safety and Health) [2004]. NIOSH respirator selection logic. 

48 Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 
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11

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18 ten Berge WF, Zwart A, Appelman LM [1986]. Concentration-time mortality response relationship of irritant and 

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21 USEPA (U.S. Environmental Protection Agency) [2014]. Integrated Risk Information System (IRIS). 

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23