EPA/630/R-96/009 October 1996 Guidelines for Reproductive Toxicity Risk Assessment Published on October 31, 1996, Federal Register 61(212):56274-56322 These guidelines replace two proposed guidelines: Proposed Guidelines for Female Reproductive Risk and Proposed Guidelines for Male Reproductive Risk, both dated June 30, 1988. Risk Assessment Forum U.S. Environmental Protection Agency Washington, DC DISCLAIMER This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. Note: This document represents the final guidelines. A number of editorial corrections have been made during conversion and subsequent proofreading to ensure the accuracy of this publication. iii CONTENTS List of Tables ................................................................. vi Federal Register Preamble ....................................................... vii Part A: Guidelines for Reproductive Toxicity Risk Assessment 1. Overview ..................................................................1 2. Definitions and Terminology ....................................................5 3. Hazard Characterization for Reproductive Toxicants ..................................6 3.1. Laboratory Testing Protocols ..............................................7 3.1.1. Introduction .....................................................7 3.1.2. Duration of Dosing ................................................7 3.1.3. Length of Mating Period ...........................................8 3.1.4. Number of Females Mated to Each Male ...............................8 3.1.5. Single- and Multigeneration Reproduction Tests ..........................8 3.1.6. Alternative Reproductive Tests ......................................11 3.1.7. Additional Test Protocols That May Provide Reproductive Data .............12 3.2. Endpoints for Evaluating Male and Female Reproductive Toxicity in Test Species ..........................................................14 3.2.1. Introduction ....................................................14 3.2.2. Couple-Mediated Endpoints .......................................15 3.2.2.1. Fertility and Pregnancy Outcomes ............................15 3.2.2.2. Sexual Behavior .........................................22 3.2.3. Male-Specific Endpoints ..........................................24 3.2.3.1. Introduction ............................................24 3.2.3.2. Body Weight and Organ Weights ............................24 3.2.3.3. Histopathologic Evaluations .................................27 3.2.3.4. Sperm Evaluations .......................................29 3.2.3.5. Paternally Mediated Effects on Offspring .......................33 3.2.4. Female-Specific Endpoints .........................................34 3.2.4.1. Introduction ............................................34 3.2.4.2. Body Weight, Organ Weight, Organ Morphology, and Histology .....35 3.2.4.3. Oocyte Production .......................................41 3.2.4.4. Alterations in the Female Reproductive Cycle ...................42 3.2.4.5. Mammary Gland and Lactation ..............................44 3.2.4.6. Reproductive Senescence ..................................45 3.2.5. Developmental and Pubertal Alterations ...............................45 3.2.5.1. Developmental Effects .....................................45 iv CONTENTS (continued) 3.2.5.2. Effects on Puberty ........................................46 3.2.5.3. Adverse Effects ..........................................47 3.2.6. Endocrine Evaluations ............................................47 3.2.6.1. Adverse Effects ..........................................50 3.2.7. In Vitro Tests of Reproductive Function ...............................50 3.3. Human Studies ........................................................51 3.3.1. Epidemiologic Studies ............................................51 3.3.1.1. Selection of Outcomes for Study .............................52 3.3.1.2. Reproductive History Studies ...............................55 3.3.1.3. Community Studies and Surveillance Programs ..................56 3.3.1.4. Identification of Important Exposures for Reproductive Effects ................................................57 3.3.1.5. General Design Considerations ..............................58 3.3.2. Examination of Clusters, Case Reports, or Series ........................61 3.4. Pharmacokinetic Considerations ...........................................62 3.5. Comparisons of Molecular Structure ........................................64 3.6. Evaluation of Dose-Response Relationships ...................................64 3.7. Characterization of the Health-Related Database ...............................66 4. Quantitative Dose-Response Analysis ............................................71 4.1. Utilization of Information in Risk Characterization ...............................74 5. Exposure Assessment ........................................................75 6. Risk Characterization ........................................................80 6.1. Overview ............................................................80 6.2. Integration of Hazard Characterization, Quantitative Dose-Response, and Exposure Assessments ...............................................81 6.3. Descriptors of Reproductive Risk ..........................................83 6.3.1. Distribution of Individual Exposures ..................................88 6.3.2. Population Exposure .............................................88 6.3.3. Margin of Exposure ..............................................89 6.3.4. Distribution of Exposure and Risk for Different Subgroups .................89 6.3.4.1. Highly Exposed ..........................................89 6.3.4.2. Highly Susceptible ........................................90 6.3.5. Situation-Specific Information ......................................91 6.3.6. Evaluation of the Uncertainty in the Risk Descriptors ......................92 6.4. Summary and Research Needs ............................................92 7. References ................................................................93 v CONTENTS (continued) Part B: Response to Science Advisory Board and Public Comments 1. Introduction ..............................................................115 2. Response to Science Advisory Board Comments ..................................115 3. Response to Public Comments ................................................117 vi LIST OF TABLES Table 1. Default assumptions in reproductive toxicity risk assessment ........................3 Table 2. Couple-mediated endpoints of reproductive toxicity .............................16 Table 3. Selected indices that may be calculated from endpoints of reproductive toxicity in test species ...................................................17 Table 4. Male-specific endpoints of reproductive toxicity ................................25 Table 5. Female-specific endpoints of reproductive toxicity ..............................36 Table 6. Categorization of the health-related database ..................................68 Table 7. Guide for developing chemical-specific risk characterizations for reproductive effects .....................................................84 vii GUIDELINES FOR REPRODUCTIVE TOXICITY RISK ASSESSMENT [FRL-5630-6] AGENCY: U.S. Environmental Protection Agency ACTION: Notice of availability of final Guidelines for Reproductive Toxicity Risk Assessment SUMMARY: The U.S. Environmental Protection Agency (EPA) is today publishing in final form a document entitled Guidelines for Reproductive Toxicity Risk Assessment (hereafter “Guidelines”). These Guidelines were developed as part of an interoffice guidelines development program by a Technical Panel of the Risk Assessment Forum. They were proposed initially in 1988 as separate guidelines for the female and male reproductive systems. Subsequently, based upon the public comments and Science Advisory Board (SAB) recommendations, changes made included combining those two guidelines, integrating the hazard identification and dose-response sections, assuming as a default that an agent for which sufficient data were available on only one sex may also affect reproductive function in the other sex, expansion of the section on interpretation of female endpoints, and consideration of the benchmark dose approach for quantitative risk assessment. These Guidelines were made available again for public comment and SAB review in 1994. This notice describes the scientific basis for concern about exposure to agents that cause reproductive toxicity, outlines the general process for assessing potential risk to humans from exposure to environmental agents, and addresses Science Advisory Board and public comments on the 1994 Proposed Guidelines for Reproductive Toxicity Risk Assessment. Subsequent reviews have included the Agency’s Risk Assessment Forum and interagency comment by members of subcommittees of the Committee on the Environment and Natural Resources of the Office of Science and Technology Policy. The EPA appreciates the efforts of all participants in the process and has tried to address their recommendations in these Guidelines. EFFECTIVE DATE: The Guidelines will be effective October 31, 1996. viii ADDRESSES: The Guidelines will be made available in the following ways: (1) The electronic version will be accessible on EPA’s Office of Research