Health Effects Support Document for Manganese Health Effects Support Document for Manganese Prepared for: U.S. Environmental Protection Agency Office of Water (4304T) Health and Ecological Criteria Division Washington, DC 20460 www.epa.gov/safewater/ccl/pdf/manganese.pdf EPA 822-R-03-003 February 2003 2 FOREWORD The Safe Drinking Water Act (SDWA), as amended in 1996, requires the Administrator of the Environmental Protection Agency to establish a list of contaminants to aid the agency in regulatory priority setting for the drinking water program. In addition, SDWA requires EPA to make regulatory determinations for no fewer than five contaminants by August 2001. The criteria used to determine whether or not to regulate a chemical on the CCL are the following: The contaminant may have an adverse effect on the health of persons. The contaminant is known to occur, or there is a substantial likelihood that the contaminant will occur, in public water systems with a frequency and at levels of public health concern. In the sole judgment of the administrator, regulation of such contaminant presents a meaningful opportunity for health risk reduction for persons served by public water systems. The Agency’s findings for all three criteria are used in making a determination to regulate a contaminant. The Agency may determine that there is no need for regulation when a contaminant fails to meet one of the criteria. The decision not to regulate is considered a final agency action and is subject to judicial review. This document provides the health effects basis for the regulatory determination for manganese. In arriving at the regulatory determination, data on toxicokinetics, human exposure, acute and chronic toxicity to animals and humans, epidemiology, and mechanisms of toxicity were evaluated. In order to avoid wasteful duplication of effort, information from the following risk assessments by the EPA and other government agencies were used in development of this document: U.S. EPA 1994a. U.S. Environmental Protection Agency. Drinking Water Criteria Document for Manganese. Office of Health and Environmental Assessment, Cincinnati, OH CEAO-CIN-D008, prepared September, 1993, revised March 31, 1994. ATSDR. 2000. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Manganese (Update). Department of Health and Human Services. Atlanta, GA. Available at http://www.atsdr.cdc.gov. U.S. EPA 1996a. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS): Manganese. Available at http://www.epa.gov/iris. Last revised December 1, 1996. In addition, primary references of studies published in peer-reviewed scientific journals relevant to human risk assessment of manganese were also used in preparing this Drinking Water Manganese — February 2003 iii Support Document for Manganese. Recent studies of manganese were identified by literature searches conducted in 1999 and 2000. Generally a Reference Dose (RfD) is provided as the assessment of long-term toxic effects other than carcinogenicity. RfD determination assumes that thresholds exist for certain toxic effects such as cellular necrosis. It is expressed in terms of milligrams per kilogram per day (mg/kg-day). In general, the RfD is an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. The carcinogenicity assessment for manganese includes a formal hazard identification. Hazard identification is a weight-of-evidence judgment of the likelihood that the agent is a human carcinogen via the oral route. Guidelines that were used in the development of this assessment may include the following: the Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1986a), Guidelines for the Health Risk Assessment of Chemical Mixtures (U.S. EPA, 1986b), Guidelines for Mutagenicity Risk Assessment (U.S. EPA, 1986c), Guidelines for Developmental Toxicity Risk Assessment (U.S. EPA, 1991a), Proposed Guidelines for Carcinogen Risk Assessment (1996b, 1999b), Guidelines for Reproductive Toxicity Risk Assessment (U.S. EPA, 1996c), and Guidelines for Neurotoxicity Risk Assessment (U.S. EPA, 1998a); Recommendations for and Documentation of Biological Values for Use in Risk Assessment (U.S. EPA, 1988); and Health Effects Testing Guidelines (OPTS series 870, 1996 drafts; U.S. EPA 40 CAR Part 798, 1997); Peer Review and Peer Involvement at the U.S. Environmental Protection Agency (U.S. EPA, 1994b); Use of the Benchmark Dose Approach in Health Risk Assessment (U.S. EPA, 1995). The chapter on occurrence and exposure to manganese through potable water was developed by the Office of Ground Water and Drinking Water. It is based primarily on unregulated contaminant monitoring (UCM) data collected under SDWA. The UCM data are supplemented with ambient water data as well as information on production, use, and discharge. Manganese — February 2003 iv ACKNOWLEDGMENTS This document was prepared under the U.S. EPA contract No. 68-C-02-009, Work Assignment No. B-02 with ICF Consulting, Fairfax, Virginia. The Lead U.S. EPA Scientist is Julie Du, Ph.D., Health and Ecological Criteria Division, Office of Science and Technology, Office of Water. Manganese — February 2003 v TABLE OF CONTENTS FOREWORD................................................................ iii ACKNOWLEDGMENTS ...................................................... v LIST OF TABLES............................................................ ix 1.0EXECUTIVE SUMMARY................................................. 1-1 2.0 IDENTITY: CHEMICAL AND PHYSICAL PROPERTIES ....................... 2-1 3.0 USES AND ENVIRONMENTAL FATE ...................................... 3-1 3.1 Production and Uses ............................................. 3-1 3.2 Sources and Environmental Fate.................................... 3-4 4.0EXPOSURE FROM DRINKING WATER.................................... 4-1 4.1 Introduction .................................................... 4-1 4.2 Ambient Occurrence ............................................. 4-1 4.3 Drinking Water Occurrence........................................ 4-4 4.4 Results....................................................... 4-10 4.5 Conclusion.................................................... 4-11 5.0 EXPOSURE FROM ENVIRONMENTAL MEDIA OTHER THAN WATER ......... 5-1 5.1 Food .......................................................... 5-1 5.1.1 Concentrations of Manganese in Food ................................ 5-1 5.1.2 Intake of Manganese From Food .................................... 5-1 5.2 Air ........................................................... 5-5 5.2.1 Concentration of Manganese in Air .................................. 5-5 5.2.2 Intake of Manganese in Air ....................................... 5-11 5.3Soil................................................................ 5-12 5.3.1 Concentration of Manganese in Soil ................................ 5-12 5.3.2 Intake of Manganese in Soil ....................................... 5-12 5.4 Other Media................................................... 5-12 5.5Summary of Exposure to Manganese in Media Other Than Water............... 5-12 6.0TOXICOKINETICS ...................................................... 6-1 6.1 Absorption ..................................................... 6-1 6.2 Distribution .................................................... 6-7 6.3 Metabolism ................................................... 6-11 6.4 Excretion ..................................................... 6-12 7.0 HAZARD IDENTIFICATION ........................................... 7-1 7.1 Human Effects .................................................. 7-1 7.1.1 Case Reports ................................................... 7-1 Manganese — February 2003 vi 7.1.2 Short-term Studies ............................................... 7-3 7.1.3 Long-Term and Epidemiological Studies ............................. 7-4 7.1.4 Beneficial Effects ................................................ 7-9 7.2 Animal Studies ................................................. 7-10 7.2.1 Acute Toxicity ................................................. 7-10 7.2.2 Short-Term Studies ............................................. 7-12 7.2.3 Subchronic Studies .............................................. 7-14 7.2.4 Neurotoxicity .................................................. 7-16 7.2.5 Developmental/Reproductive Toxicity .............................. 7-25 7.2.6 Chronic Toxicity ............................................... 7-33 7.2.7 Carcinogenicity ................................................ 7-34 7.3 Other Key Data ................................................ 7-37 7.3.1 Mutagenicity/Genotoxicity ....................................... 7-37 7.3.2 Immunotoxicity ................................................ 7-41 7.3.3 Hormonal Disruption ............................................ 7-41 7.3.4 Physiological or Mechanistic Studies ............................... 7-42 7.3.5 Structure-Activity Relationship .................................... 7-45 7.4 Hazard Characterization .......................................... 7-45 7.4.1 Synthesis and Evaluation of Major Noncancer Effects .................. 7-45 7.4.2 Synthesis and Evaluation of Carcinogenic Effects ..................... 7-48 7.4.3 Mode of Action and Implications in Cancer Assessment ................ 7-49 7.4.4 Weight of Evidence