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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 IRON PENTACARBONYL

16

17

18 [CAS NO. 13463-40-6] 

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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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 
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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 iron pentacarbonyl (CAS # 13463-40-6). 

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

30 to ensure transparency and scientific credibility. 

31

32 John Howard, M.D. 

33 Director 

34 National Institute for Occupational Safety and Health 
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iv

1 Centers for Disease Control and Prevention
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v

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 IRON PENTACARBONYL ...................................................................................1

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

9 1.3 GENERAL SUBSTANCE INFORMATION .........................................................................................................................2

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

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

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

13 5.0 REFERENCES ................................................................................................................................................ 11

14

15

16

17

18
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vi

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 LC50 median lethal concentration 

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

14 LEL lower explosive limit 

15 LOAEL lowest observed adverse effect level 

mg/m3 16 milligram(s) per cubic meter 

17 NAC National Advisory Committee 

18 NAS National Academy of Sciences 

19 NIOSH National Institute for Occupational Safety and Health 

20 NOAEL no observed adverse effect level 

21 OSHA Occupational Safety and Health Administration 

22 PEL permissible exposure limit 

23 ppm parts per million 

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

25 rate 

26 REL recommended exposure limit 

27 SCP Standard Completion Program 

28 STEL short term exposure limit 

29 TLV threshold limit value 

30 TWA time weighted average 

31 UEL upper explosive limit 

32 WEEL workplace environmental exposure level 
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vii

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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viii

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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ix

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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x

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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xi

1 Acknowledgments 

2

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

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

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

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

7

8 Education and Information Division 

9 Devin Baker, M.Ed. 

10 Charles L. Geraci, Ph.D. 

11 Thomas J. Lentz, Ph.D. 

12 Richard Niemeier, Ph.D. 

13 Chris Sofge, Ph.D. 

14

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

16 technical review of this report. 

17

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

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

20 University 

21

22 Richard B. Schlesinger, Ph.D., Fellow A.T.S., Senior Associate Dean for Academic Affairs and Research 

23 Professor of Biology, Dyson College of Arts and Sciences, Pace University 

24 
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1

1 1.0 Introduction 

2 1.1 Overview of the IDLH Value for Iron Pentacarbonyl 

3

4 IDLH Value: 0.4 ppm

5

6 Basis for IDLH Value: The IDLH value is based on a rat non-lethality concentration of 5.2 ppm in the 4-hour 

7 Biodynamics [1988] study, which corresponds to a concentration of 10.4 ppm after a 30-minute duration 

8 adjustment. Reported effects at this concentration included lacrimation and nasal discharge, which are classified 

9 as potentially escape-impairing. Applying a composite uncertainty factor of 30 to account for adjusting from a 

10 LOAEL to NOAEL, steep exposure-response relationship, interspecies differences and human variability yields 

11 an IDLH value of 0.4 ppm. 

12

13 1.2 Purpose 

14

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

16 exposures to iron pentacarbonyl and (2) the rationale behind the Immediately Dangerous to Life or Health (IDLH) 

17 value for iron pentacarbonyl. IDLH values are developed based on the scientific rationale and logic outlined in the 

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

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

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

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

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

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

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

25 NOAELs, LOAELs, LC50 values). For iron pentacarbonyl, the in-depth literature search was conducted through 

26 February 2014. 

27

28

29
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2

1 1.3 General Substance Information 

2

3 Chemical: Iron pentacarbonyl 

4 CAS No: 13463-40-6 

Synonyms: Iron carbonyl; Pentacarbonyliron* 5

Chemical category: Iron compounds; metal carbonyls† 6

7

8

9 Structural formula: 

10

11

12

13

14 Table 1 highlights selected physiochemical properties of iron pentacarbonyl relevant to IDLH conditions. Table 2 

15 provides alternative exposure guidelines for iron pentacarbonyl. Table 3 summarizes the Acute Exposure 

16 Guidelines Level (AEGL) values for iron pentacarbonyl. 

17

18 Table 1: Physiochemical Properties of Iron Pentacarbonyl 

19

Property Value 

Molecular weight 195.99‡

Chemical formula C5FeO5

Description Colorless to yellow to dark red, oily 

liquid 

Odor Moldy, musty

Odor Threshold Not available 

UEL 12.5†

LEL 3.7†

Vapor pressure 40 mmHg at 30.56°C (87°F)§

Flash point -15°C (5°F)‡

Ignition temperature 320°C (608°F)‡

Solubility Very slightly soluble in water†

Abbreviation: oC – Celsius; o 20 F – Fahrenheit; mmHg – millimeter mercury; LEL – lower explosive limit; UEL – upper explosive limit * 21 NLM [2014] 

† 22 IFA [2014] 

Fe

C–

C–

C–

C–

C–

O+

O+

O+

+O

O+
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3

‡ 1 HSDB [2014] 

§ 2 OSHA [1989] 

3

4

5

6 Table 2: Alternative Exposure Guidelines for Iron Pentacarbonyl 

7

Organization Value 

Original (SCP) IDLH value [NIOSH 2014] None 

NIOSH REL [2014] Not available 

OSHA PEL [2014] 0.1 ppm TWA; 0.2 ppm STEL 

ACGIH TLV [2014] Not available 

AIHA ERPG [2013] Not available 

AIHA WEEL [2013] Not available 

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

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

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

11 REL – recommended exposure limit; SCP – Standards Completion Program; WEEL – workplace environmental exposure level 
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1 Table 3: AEGL Values for Iron Pentacarbonyl 

2

Classification 10-min 30-min 1-hour 4-hour 8-hour Endpoint [AEGL-1 NR NR NR NR NR Not recomAEGL-2 0.077 ppm 

0.61 mg/m3

0.077 ppm 0.61 mg/m3

0.060 ppm 0.48 mg/m3

0.037 ppm 0.30 mg/m3

0.025 ppm 0.20 mg/m3

Based on AEGL-3 v

AEGL-3 0.23 ppm 

1.8 mg/m3

0.23 ppm 1.8 mg/m3

0.18 ppm 1.4 mg/m3

0.11 ppm 0.88 mg/m3

0.075 ppm 0.60 mg/m3

Estimated (1.0 ppm danalysis [Bor 3; unceboth intersindividual 

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 [2010] 

5
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5

1 2.0 Animal Toxicity Data 

2

3 The majority of acute studies for iron pentacarbonyl provided data on lethality, with little additional information 

4 to assess potential escape-impairing effects. Using a dynamic exposure chamber without analytical monitoring, 

5 Gage [1970] reported that a single 5.5 hour exposure to 33 ppm was lethal to 3 of 8 rats, but no effects were seen 

6 in rats exposed for eighteen 5.5 hour periods at 7 ppm. Postmortem examination of the rats that died showed 

7 pulmonary edema, indicating that lung effects are a critical target for this chemical. Sunderman et al. [1959] 

8 conducted lethality studies with mice and rats with reported 30-minute LC50 values of 273 ppm and 114 ppm, 

9 respectively. Biodynamics [1988] reported that rats exposed to 5.2 ppm of iron pentacarbonyl for 4 hours showed 

10 effects 1 to 2 hours post exposure, but essentially no toxicity during exposure. The observed effects included 

11 lacrimation and nasal discharge at a slightly higher incidence than controls. Necropsy of these rats revealed red 

12 lungs in some of the rats, but the actual number was not reported, and the observation was considered of 

13 equivocal significance on the basis of gross pathology only. Together, the studies of Gage [1970] and 

14 Biodynamics [1988] show minimal irritant effects in the range of 5 to 7 ppm of iron pentacarbonyl even for single 

15 acute exposure periods significantly longer than 30-minutes. BASF [1995] reported 1 of 10 rats died following a 

16 single 6-hour exposure to 2.91 ppm of iron pentacarbonyl. A total of 5/10 rats died within 4 days after receiving 

17 two 6-hour exposures. Because of the delayed mortality seen in this and other studies, it is not known whether 

18 additional rats would have died following the single exposure if there had been additional post-exposure 

19 monitoring. NAS [2010] calculated an LC01 value of 1.9 ppm and a BMCL05 for lethality of 0.8 ppm, assuming 

20 that a single exposure would have killed 5/10 animals, as a worst case scenario in light of the delayed deaths. 

21 However, rats exposed to 1.0 ppm for 5 days/week for 1 month did not exhibit any clinical signs, suggesting a 

22 steep exposure-response curve, and that 1.0 ppm is a very conservative estimate of the lethality threshold from a 

23 single exposure. 

24

25 The acute toxicity studies show a significant difference in lethal concentrations in rats across the available studies. 

26 It is convenient that the study by Sunderman et al. [1959] was for the duration of interest and included sufficient 

27 information to calculate an LC50 value, but a static exposure scenario was used, leading to significant uncertainty 

28 in the actual exposure levels. The Biodynamics [1988] and BASF [1995] studies were conducted using modern 

29 exposure methods and identified much lower effect levels, but involved greater time extrapolation, and the BASF 

30 [1995] study includes the additional uncertainties due to the multiple exposures and inadequate information on 
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6

1 post-exposure deaths following a single exposure. Thus, the appropriate IDLH value derivation would yield a 

2 value generally near this exposure range. 

3

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

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

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

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

8 applied to calculate the derived values. 

9

10 
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1 Table 4: Lethal Concentration Data for Iron Pentacarbonyl

2

Reference Species LC50

(ppm) 

LCLo

(ppm) 

Time (min) 

Adjusted 30-minute Concentration* (ppm) 

Composite Uncertainty Factor 

Derived Value (ppm)†

Sunderman et al. [1959] Mouse 273273 -- 30 273273 30‡ 9.11 Armit [1980] Rabbit 250 -- 45 286 30‡ 9.5 

Sunderman et al. [1959] Rat 118 -- 30 118 30‡ 3.9 Biodynamics [1988] Rat 10 -- 240 20 30‡ 0.7 BASF [1995] Rat 3± -- 720 9 30‡ 0.3 BASF [1995] Rat -- 3§ 360 7 10^ 0.7 

BASF [1995] Rat -- 1** 360 2.3 10^ 0.2 

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

* 7 For exposures greater than 30 minutes the ten Berge et al. [1986] relationship is used for adjustment (Cn 8 x t = k); empirically estimated n values were not available, therefore the default values were used, 

9 n = 3 for exposures greater than 30 minutes and n = 1 for exposures less than 30 minutes. 

† 10 The derived value is the result of the adjusted 30-minute concentration divided by the composite uncertainty factor. ‡ 11 Composite uncertainty factor to account for adjustment of LC50 values to LC01 values, use of lethal concentration threshold in animals, inte

12 human variability. 

± 13 5/10 rats died within 4 days after receiving two 6-hour exposures § 14 1/10 rats died after a single 6-hour exposure ^ 15 Composite uncertainty factor to account for lethal concentration threshold in animals, interspecies differences and human variability. ** 16 Modified BMCL05 for lethality after a single 6-hour exposure 

171819202122232425
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agency determination or policy. 

1

2

34

5 Table 5: Non-lethal Concentration Data for Iron Pentacarbonyl 6

Reference Species NOAEL 

(ppm) 

LOAEL (ppm) 

Time (min) 

Adjusted 30-minute Concentration* (ppm) 

Composite Uncertainty Factor 

Derived Value (ppm)†

Biodynamics [1988] + Rat -- 5.2 240 10.4 30± 0.4 

7 Abbreviation: NOAEL – no observed adverse effect level; min – minute; LOAEL – lowest observed adverse effect level; ppm – parts per million8

* 9 For exposures greater than 30 minutes the ten Berge et al. [1986] relationship is used for adjustment (Cn 10 x t = k); empirically estimated n values were not available, therefore the default values were used, 

11 n = 3 for exposures greater than 30 minutes and n = 1 for exposures less than 30 minutes. 

† 12 The derived value is the result of the adjusted 30-minute concentration divided by the composite uncertainty factor. + 13 Identified study is the primary basis of the IDLH value for iron pentacarbonyl. ± 14 Composite uncertainty factor assigned to account for adjusting from a LOAEL to NOAEL, steep exposure-response relationship, interspec

15 variability
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9

1 3.0 Human Data 

2 No information was identified that provided adequate estimates of observed effects following exposure in 

3 humans. Stokinger [1981] reported that the effects of human exposure to iron pentacarbonyl are similar to those 

4 of nickel carbonyl exposure. Such effects are giddiness and headache, dyspnea, and vomiting that was alleviated 

5 after removal from exposure. Symptoms such as fever, cyanosis and coughing lasting up 36 hours after exposure 

6 have also been reported. Death may occur several days after exposure.

7 4.0 Summary 

8

9 The assembled data on iron pentacarbonyl reveal a steep exposure-response relationship and a small gap between 

10 concentrations associated with severe non-lethal effects and death in test animals. Reported effects of concern 

11 include delayed onset of death following acute exposure. The IDLH value for iron pentacarbonyl is based on a rat 

12 non-lethality concentration of 5.2 ppm in the 4-hour Biodynamics [1988] study, which corresponds to a 

13 concentration of 10.4 ppm after a 30-minute duration adjustment. Reported effects at this concentration included 

14 lacrimation and nasal discharge, which are classified as potentially escape impairing. Applying a composite 

15 uncertainty factor of 30 to account for extrapolation from a LOAEL to a NOAEL, severe effects in animals (i.e., 

16 steep exposure-response relationship), interspecies differences and human variability, results in an IDLH value of 

17 0.4 ppm. 

18

19 It should be noted that the IDLH value for iron pentacarbonyl differs by more than an order of magnitude from 

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

21 which it is predicted that the general population, including susceptible individuals, could experience irreversible 

22 or other serious, long-lasting adverse health effects or an impaired ability to escape [NAS 2001]. Data to 

23 calculate an AEGL-2 value for iron pentacarbonyl were deemed insufficient resulting in the establishment of an 

24 AEGL-2 equal to 1/3 of the calculated AEGL-3 value, which is intended to represent an airborne concentration of 

25 a substance above which it is predicted that the general population, including susceptible individuals, could 

26 experience life-threatening health effects or death [NAS 2001, 2010]. The AEGL-3 value for 30-minutes was set 

27 at 0.23 ppm and was based on lethal threshold estimates in rats reported in BASF [1995]. NIOSH used non28 lethality data reported in Biodynamics [1988] as the basis of the IDLH value of 0.4 ppm for iron pentacarbonyl. 
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10

1 The small difference between the AEGL-3 value and IDLH value are caused by alternative primary data, selection 

2 of the endpoints and duration adjustments. 
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11

1 5.0 References 

2

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

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6 AIHA (American Industrial Hygiene Association) [2006]. AIHA Emergency Response Planning (ERP) 

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8 https://www.aiha.org/get9 involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Documents/ERP-SOPs2006.pdf. 

10

11 AIHA (American Industrial Hygiene Association) [2013]. Emergency response planning guidelines (ERPG) and 

12 workplace environmental exposure levels (WEEL) handbook. Fairfax, VA: American Industrial Hygiene 

13 Association Press, https://www.aiha.org/get14 involved/AIHAGuidelineFoundation/EmergencyResponsePlanningGuidelines/Pages/default.aspx. 

15

16 Armit HW [1908]. The Toxicology of Nickel Carbonyl. Part II. J Hygiene 8:565–600. 

17

18 BASF [1995]. Study on inhalation toxicity of eisenpentacarbonyl as a vapor in rats-28 day test. Ludwigshafen, 

19 Germany: BASF (Badische Anilin & Soda Fabrik), Department of Toxicology. Environmental Protection 

20 Agency, Office of Toxics Substances, Document #88-950000244. 

21

22 Biodynamics [1988]. An acute inhalation toxicity study of iron pentacarbonyl in the rat. Final Report. 

23 Environmental Protection Agency, Office of Toxic Substances. Document #88-920001300. 

24

25 EPA [2010]. Integrated Risk Information System (IRIS): glossary [http://www.epa.gov/iris/help_gloss.htm]. 

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27 Gage JC [1970]. The subacute inhalation toxicity of 107 industrial chemicals. Br J Ind Med 27:1–18. 

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29 HSDB (Hazardous Substances Data Bank) [2014]. HSDB. National Library of Medicine, Bethesda, MA, 

30 http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB. 

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32 IFA (Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung) [2014]. GESTIS: Database on 

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37 NAS (National Academy of Sciences) [2001]. Standing operating procedures for developing acute exposure 

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40 http://www.nap.edu/. 

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42 NAS [2010]. Acute Exposure Guideline Levels (AEGLs) for selected airborne chemicals. Vol. 6. - Chapter 7: 

43 Iron pentacarbonyl. National Academy of Science, Committee on Toxicology and Committee on Acute Exposure 

44 Guideline Levels, Board on Environmental Studies and Toxicology, National Research Council. Washington, DC: 

45 National Academy Press, http://www.epa.gov/oppt/aegl/pubs/iro

46 http://www.epa.gov/oppt/aegl/pubs/iron_pentacarbonyl_final_volume6_2007.pdfn_pentacarbonyl_final_volume6

47 _2007.pdf]. 
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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. 

12

1

2 NIOSH [2004]. NIOSH respirator selection logic. Cincinnati, OH: U.S. Department of Health and Human 

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10 NIOSH [2014]. NIOSH Current Intelligence Bulletin 66: Derivation of Immediately Dangerous to Life or Health 

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12 and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2014-

13 100. 

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15 NLM (National Library of Medicine) [2013]. ChemIDplus lite 

16 [http://chem.sis.nlm.nih.gov/chemidplus/chemidlite.jsp]. Date accessed: March 15, 2013. 

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18 OSHA [2013]. OSHA occupational chemical database: iron pentacarbonyl, as Fe 

19 [http://www.osha.gov/chemicaldata/chemResult.html?recNo=245]. Date accessed: March 15, 2013. 

20

21 OSHA [2011]. OSHA PEL project documentation: iron pentacarbonyl [http://www.cdc.gov/niosh/pel88/13463-

22 40.html]. Date accessed: June 21, 2013. 

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24 OSHA (Occupational Safety and Health Administration) [2010]. Occupational Safety and Health Standards. 29 

25 CFR 1910. Subpart Z -- Toxic and Hazardous Substances. OSHA; Washington, DC 

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32 Sunderman F, West B, Kincaid J [1959]. A toxicity study of iron pentacarbonyl. Arch Ind Health 19:11–13. 

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

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