September 2000

CHROMIUM ii

The use of company or product name(s) is for identification only and does not imply endorsement by the

Agency for Toxic Substances and Disease Registry.

CHROMIUM iii

Toxicological profiles are revised and republished as necessary, but no less than once every three years.

For information regarding the update status of previously released profiles, contact ATSDR at:

Agency for Toxic Substances and Disease Registry

Division of Toxicology/Toxicology Information Branch

1600 Clifton Road NE, E-29

Atlanta, Georgia 30333

CHROMIUM vi

Disease Registry

*Legislative Background

The toxicological profiles are developed in response to the Superfund Amendments and

Reauthorization Act (SARA) of 1986 (Public law 99-499) which amended the Comprehensive

Environmental Response, Compensation, and Liability Act of 1980 (CERCLA or Superfund). This

public law directed ATSDR to prepared toxicological profiles for hazardous substances most commonly

found at facilities on the CERCLA National Priorities List and that pose the most significant potential

threat to human health, as determined by ATSDR and the EPA. The availability of the revised priority

FR 18744); April 17, 1987 (52 FR 12866); October 20, 1988 (53 FR 41280); October 26, 1989 (54 FR

43619); October 17, 1990 (55 FR 42067); October 17, 1991 (56 FR 52166); October 28, 1992 (57 FR

48801); and February 28, 1994 (59 FR 9486). Section 104(i)(3) of CERCLA, as amended, directs the

Administrator of ATSDR to prepare a toxicological profile for each substance on the list.

CHROMIUM vii

Toxicological Profiles are a unique compilation of toxicological information on a given hazardous

substance. Each profile reflects a comprehensive and extensive evaluation, summary, and interpretation of

available toxicologic and epidemiologic information on a substance. Health care providers treating

patients potentially exposed to hazardous substances will find the following information helpful for fast

answers to often-asked questions.

patients about possible exposure to a hazardous substance. It explains a substance’s relevant

toxicologic properties in a nontechnical, question-and-answer format, and it includes a review of

the general health effects observed following exposure.

reported in this section.

the clinical setting. Please refer to the Public Health Statement to identify

general health effects observed following exposure.

issues:

The following additional material can be ordered through the ATSDR Information Center:

exposure history and how to conduct one are described, and an example of a thorough exposure

CHROMIUM viii

(prehospital) and hospital medical management of patients exposed during a hazardous materials incident.

Volumes I and II are planning guides to assist first responders and hospital emergency department

exposed to hazardous materials.

injury, and disability related to the interactions between people and their environment outside the

3724 • Phone: 770-488-7000 • FAX: 770-488-7015.

diseases and injuries, responds to requests for assistance by investigating problems of health and

safety in the workplace, recommends standards to the Occupational Safety and Health

Administration (OSHA) and the Mine Safety and Health Administration (MSHA), and trains

SW, Washington, DC 20201 • Phone: 800-356-4674 or NIOSH Technical Information Branch,

Robert A. Taft Laboratory, Mailstop C-19, 4676 Columbia Parkway, Cincinnati, OH 45226-1998

• Phone: 800-35-NIOSH.

biomedical research on the effects of chemical, physical, and biologic environmental agents on

Research Triangle Park, NC 27709 • Phone: 919-541-3212.

AOEC, 1010 Vermont Avenue, NW, #513, Washington, DC 20005 • Phone: 202-347-4976 •

FAX: 202-347-4950 • e-mail: aoec@dgs.dgsys.com • AOEC Clinic Director: http://occ-envmed.

mc.duke.edu/oem/aoec.htm.

physicians and other health care providers specializing in the field of occupational and

60005 • Phone: 847-228-6850 • FAX: 847-228-1856.

CHROMIUM ix

Sharon Wilbur

ATSDR, Division of Toxicology, Atlanta, GA

Lisa Ingerman, Ph.D.

Syracuse Research Corporation, Portland, OR

Mario Citra, Ph.D.

Syracuse Research Corporation, North Syracuse, NY

Mark Osier, Ph.D

Syracuse Research Corporation, North Syracuse, NY

Dave Wohlers, Ph.D.

Syracuse Research Corporation, North Syracuse, NY

1. Health Effects Review. The Health Effects Review Committee examines the health effects

chapter of each profile for consistency and accuracy in interpreting health effects and classifying

end points.

2. Minimal Risk Level Review. The Minimal Risk Level Workgroup considers issues relevant to

substance-specific minimal risk levels (MRLs), reviews the health effects database of each

profile, and makes recommendations for derivation of MRLs.

3. Data Needs Review. The Research Implementation Branch reviews data needs sections to assure

consistency across profiles and adherence to instructions in the Guidance.

CHROMIUM xi

A peer review panel was assembled for chromium. The panel consisted of the following members:

1. Dr. William Berndt, Professor, Department of Pharmacology, University of Nebraska Medical

Center, Omaha, Nebraska.

2. Dr. Max Costa, Professor, Department of Environmental Medicine, New York University School of

Medicine, Tuxedo, New York.

3. Dr. Steven R. Patierno, Professor of Pharmacology, Genetics and Urology, The George Washington

University Medical School; Professor of Environmental and Occupational Health, The George

Washington University School of Public Health, Washington, D.C.

4. Dr. Elizabeth Snow, Assistant Professor, Nelson Institute of Environmental Medicine, New York

University Medical Center, Tuxedo, New York.

These experts collectively have knowledge of chromium’s physical and chemical properties, toxicokinetics,

key health end points, mechanisms of action, human and animal exposure, and quantification of

risk to humans. All reviewers were selected in conformity with the conditions for peer review specified

in Section 104(I)(13) of the Comprehensive Environmental Response, Compensation, and Liability Act,

as amended.

Scientists from the Agency for Toxic Substances and Disease Registry (ATSDR) have reviewed the peer

reviewers' comments and determined which comments will be included in the profile. A listing of the

peer reviewers' comments not incorporated in the profile, with a brief explanation of the rationale for their

exclusion, exists as part of the administrative record for this compound. A list of databases reviewed and

a list of unpublished documents cited are also included in the administrative record.

The citation of the peer review panel should not be understood to imply its approval of the profile's final

content. The responsibility for the content of this profile lies with the ATSDR.

CHROMIUM xiii

FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

QUICK REFERENCE FOR HEALTH CARE PROVIDERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

CONTRIBUTORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

PEER REVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii

LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix

1. PUBLIC HEALTH STATEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 WHAT IS CHROMIUM? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 WHAT HAPPENS TO CHROMIUM WHEN IT ENTERS THE ENVIRONMENT? . . . . . . . 2

1.3 HOW MIGHT I BE EXPOSED TO CHROMIUM? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.4 HOW CAN CHROMIUM ENTER AND LEAVE MY BODY? . . . . . . . . . . . . . . . . . . . . . . . . 5

1.5 HOW CAN CHROMIUM AFFECT MY HEALTH? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.6 HOW CAN CHROMIUM AFFECT CHILDREN? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.7 HOW CAN FAMILIES REDUCE THE RISK OF EXPOSURE TO CHROMIUM? . . . . . . . . 9

1.8 IS THERE A MEDICAL TEST TO DETERMINE WHETHER I HAVE BEEN EXPOSED

TO CHROMIUM? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.9 WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT MADE TO

PROTECT HUMAN HEALTH? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.10 WHERE CAN I GET MORE INFORMATION? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2. HEALTH EFFECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.2 DISCUSSION OF HEALTH EFFECTS BY ROUTE OF EXPOSURE . . . . . . . . . . . . . . . . . 14

2.2.1 Inhalation Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.2.1.1 Death . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.2.1.2 Systemic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.2.1.3 Immunological and Lymphoreticular Effects . . . . . . . . . . . . . . . . . . . . . . 49

2.2.1.4 Neurological Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

2.2.1.5 Reproductive Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

2.2.1.6 Developmental Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

2.2.1.7 Genotoxic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

2.2.1.8 Cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

2.2.2 Oral Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

2.2.2.1 Death . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

2.2.2.2 Systemic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

2.2.2.3 Immunological and Lymphoreticular Effects . . . . . . . . . . . . . . . . . . . . . . 98

2.2.2.4 Neurological Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

2.2.2.5 Reproductive Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

2.2.2.6 Developmental Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

2.2.2.7 Genotoxic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

2.2.2.8 Cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

2.2.3 Dermal Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

CHROMIUM xiv

2.2.3.1 Death . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

2.2.3.2 Systemic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

2.2.3.3 Immunological and Lymphoreticular Effects . . . . . . . . . . . . . . . . . . . . . 119

2.2.3.4 Neurological Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

2.2.3.5 Reproductive Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

2.2.3.6 Developmental Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

2.2.3.7 Genotoxic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

2.2.3.8 Cancer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

2.3 TOXICOKINETICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

2.3.1 Absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

2.3.1.1 Inhalation Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

2.3.1.2 Oral Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

2.3.1.3 Dermal Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

2.3.2 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

2.3.2.1 Inhalation Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

2.3.2.2 Oral Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

2.3.2.3 Dermal Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

2.3.2.4 Other Routes of Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

2.3.3 Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

2.3.4 Elimination and Excretion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

2.3.4.1 Inhalation Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

2.3.4.2 Oral Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

2.3.4.3 Dermal Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

2.3.4.4 Other Routes of Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

2.3.5 Physiologically based Pharmacokinetic (PBPK)/Pharmacodynamic (PD) Models . 154

2.3.5.1 Summary of PBPK Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

2.3.5.2 Chromium PBPK Model Comparison. . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

2.3.5.3 Discussion of Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

2.4 MECHANISMS OF ACTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

2.4.1 Pharmacokinetic Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

2.4.2 Mechanisms of Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

2.4.3 Animal-to-Human Extrapolations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

2.5 RELEVANCE TO PUBLIC HEALTH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

2.6 ENDOCRINE DISRUPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212

2.7 CHILDREN’S SUSCEPTIBILITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212

2.8 BIOMARKERS OF EXPOSURE AND EFFECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

2.8.1 Biomarkers Used to Identify or Quantify Exposure to Chromium . . . . . . . . . . . . . 217

2.8.2 Biomarkers Used to Characterize Effects Caused by Chromium . . . . . . . . . . . . . . 225

2.9 INTERACTIONS WITH OTHER CHEMICALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

2.10 POPULATIONS THAT ARE UNUSUALLY SUSCEPTIBLE . . . . . . . . . . . . . . . . . . . . . . 230

2.11 METHODS FOR REDUCING TOXIC EFFECTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

2.11.1 Reducing Peak Absorption Following Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . 231

2.11.2 Reducing Body Burden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

2.11.3 Interfering with the Mechanism of Action for Toxic Effects . . . . . . . . . . . . . . . . . . 235

2.12 ADEQUACY OF THE DATABASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

2.12.1 Existing Information on Health Effects of Chromium . . . . . . . . . . . . . . . . . . . . . . . 238

2.12.2 Identification of Data Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

2.12.3 Ongoing Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

3. CHEMICAL AND PHYSICAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

3.1 CHEMICAL IDENTITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

CHROMIUM xv

3.2 PHYSICAL AND CHEMICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

4. PRODUCTION, IMPORT/EXPORT, USE, AND DISPOSAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

4.1 PRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

4.2 IMPORT/EXPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277

4.3 USE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277

4.4 DISPOSAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

5. POTENTIAL FOR HUMAN EXPOSURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

5.1 OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281

5.2 RELEASES TO THE ENVIRONMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

5.2.1 Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

5.2.2 Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290

5.2.3 Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291

5.3 ENVIRONMENTAL FATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291

5.3.1 Transport and Partitioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291

5.3.2 Transformation and Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

5.3.2.1 Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

5.3.2.2 Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

5.3.2.3 Sediment and Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

5.4 LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENT . . . . . . . . . . . . . . . 296

5.4.1 Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297

5.4.2 Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298

5.4.3 Sediment and Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299

5.4.4 Other Environmental Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300

5.5 GENERAL POPULATION AND OCCUPATIONAL EXPOSURE . . . . . . . . . . . . . . . . . . 302

5.6 EXPOSURES OF CHILDREN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306

5.7 POPULATIONS WITH POTENTIALLY HIGH EXPOSURES . . . . . . . . . . . . . . . . . . . . . . 307

5.8 ADEQUACY OF THE DATABASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309

5.8.1 Identification of Data Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310

5.8.2 Ongoing Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314

6. ANALYTICAL METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315

6.1 BIOLOGICAL SAMPLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315

6.2 ENVIRONMENTAL SAMPLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319

6.3 ADEQUACY OF THE DATABASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325

6.3.1 Identification of Data Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325

6.3.2 Ongoing Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326

7. REGULATIONS AND ADVISORIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327

8. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339

9. GLOSSARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413

APPENDICES

A. ATSDR MINIMAL RISK LEVELS AND WORKSHEETS . . . . . . . . . . . . . . . . . . . . . . . . . A-1

B. USER’S GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

CHROMIUM xvi

C. ACRONYMS, ABBREVIATIONS, AND SYMBOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

CHROMIUM xviii

2-1 Levels of Significant Exposure to Chromium—Inhalation . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2-2 Levels of Significant Exposure to Chromium—Oral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

2-3 Conceptual Representation of a Physiologically Based Pharmacokinetic (PBPK) Model for

a Hypothetical Chemical Substance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

2-4 A Physiologically Based Model of Chromium Kinetics in the Rat . . . . . . . . . . . . . . . . . . . . 160

2-5 Linear Relationship Between Water Soluble Chromium Concentrations in Workroom Air

and the Chromium Concentrations in Blood and Urine at the End of a 5-Day Shift in Workers

of a Dichromate Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220

2-6 Relationship Between Water-Soluble Chromium(VI) Concentration in Workroom Air (CrA)

and Daily Increase in Urinary Chromium Levels (CrU) (Pre-exposure Values were Subtracted

from End-of-Shift Values). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

2-7 Existing Information on Health Effects of Chromium(VI) . . . . . . . . . . . . . . . . . . . . . . . . . . 239

2-8 Existing Information on Health Effects of Chromium(III) . . . . . . . . . . . . . . . . . . . . . . . . . . . 240

5-1 Frequency of NPL Sites with Chromium Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

5-2 Frequency of NPL Sites with Chromium(VI) Contamination . . . . . . . . . . . . . . . . . . . . . . . . 283

CHROMIUM xx

2-1 Levels of Significant Exposure to Chromium—Inhalation . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2-2 Levels of Significant Exposure to Chromium—Oral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

2-3 Levels of Significant Exposure to Chromium—Dermal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

2-4 Parameters of the O’Flaherty PBPK Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

2-8 Ongoing Studies on Chromium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

3-1 Chemical Identity of Chromium and Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260

3-2 Physical and Chemical Properties of Chromium and Compounds . . . . . . . . . . . . . . . . . . . . . 266

4-1 Facilities that Manufacture or Process Chromium and Chromium Compounds . . . . . . . . . . 274

4-2 Historical Use of Chromium in the United States and Western World . . . . . . . . . . . . . . . . . 278

5-1 Estimates of U.S. Atomospheric Chromium Emissions from Anthropogenic Sources . . . . . 286

5-2 Releases to the Environment from Facilities that Manufacture or Process Chromium

and Chromium Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

5-3 Chromium Content in Various U.S. Foods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301

5-4 Chromium Content in Tissues and Body Fluids of the General Population . . . . . . . . . . . . . . 304

5-5 Industries that May be Sources of Chromium Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305

6-1 Analytical Methods for Determining Chromium in Biological Materials . . . . . . . . . . . . . . . 316

6-2 Analytical Methods for Determining Chromium in Environmental Samples . . . . . . . . . . . . 320

7-1 Regulations and Guidelines Applicable to Chromium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

CHROMIUM 1