Silicon Tetrafluoride INTERIM: 06-2008 1 2 3 4 ACUTE EXPOSURE GUIDELINE LEVELS (AEGLs) 5 FOR 6 Silicon Tetrafluoride 7 (CAS Reg. No. 7783-61-1) 8 9 Si-F4 10 11 12 13 14 INTERIM 15 16 17 18 19 20 21 22 Silicon Tetrafluoride INTERIM: 06-2008/ Page 2 of 26 1 2 ACUTE EXPOSURE GUIDELINE LEVELS (AEGLs) 3 FOR 4 SILICON TETRAFLUORIDE 5 (CAS Reg. No. 7783-61-1) 6 7 8 INTERIM 9 10 Silicon Tetrafluoride INTERIM: 06-2008/ Page 3 of 26 1 2 PREFACE 3 4 Under the authority of the Federal Advisory Committee Act (FACA) P. L. 92-463 of 5 1972, the National Advisory Committee for Acute Exposure Guideline Levels for Hazardous 6 Substances (NAC/AEGL Committee) has been established to identify, review and interpret 7 relevant toxicologic and other scientific data and develop AEGLs for high priority, acutely toxic 8 chemicals. 9 10 AEGLs represent threshold exposure limits for the general public and are applicable to 11 emergency exposure periods ranging from 10 minutes to 8 hours. Three levels C AEGL-1, 12 AEGL-2 and AEGL-3 C are developed for each of five exposure periods (10 and 30 minutes, 1 13 hour, 4 hours, and 8 hours) and are distinguished by varying degrees of severity of toxic effects. 14 The three AEGLs are defined as follows: 15 16 AEGL-1 is the airborne concentration (expressed as parts per million or milligrams per 17 cubic meter [ppm or mg/m3]) of a substance above which it is predicted that the general 18 population, including susceptible individuals, could experience notable discomfort, irritation, or 19 certain asymptomatic, non-sensory effects. However, the effects are not disabling and are 20 transient and reversible upon cessation of exposure. 21 22 AEGL-2 is the airborne concentration (expressed as ppm or mg/m3) of a substance above 23 which it is predicted that the general population, including susceptible individuals, could 24 experience irreversible or other serious, long-lasting adverse health effects or an impaired ability 25 to escape. 26 27 AEGL-3 is the airborne concentration (expressed as ppm or mg/m3) of a substance above 28 which it is predicted that the general population, including susceptible individuals, could 29 experience life-threatening health effects or death. 30 31 Airborne concentrations below the AEGL-1 represent exposure levels that could produce 32 mild and progressively increasing but transient and nondisabling odor, taste, and sensory 33 irritation or certain asymptomatic, non-sensory effects. With increasing airborne concentrations 34 above each AEGL, there is a progressive increase in the likelihood of occurrence and the severity 35 of effects described for each corresponding AEGL. Although the AEGL values represent 36 threshold levels for the general public, including susceptible subpopulations, such as infants, 37 children, the elderly, persons with asthma, and those with other illnesses, it is recognized that 38 individuals, subject to unique or idiosyncratic responses, could experience the effects described 39 at concentrations below the corresponding AEGL 40 41 Silicon Tetrafluoride INTERIM: 06-2008/ Page 4 of 26 1 TABLE OF CONTENTS 2 PREFACE.....................................................................................................................................................3 3 LIST OF TABLES........................................................................................................................................6 4 1. INTRODUCTION................................................................................................................................8 5 2. HUMAN TOXICITY DATA...............................................................................................................8 6 3. ANIMAL TOXICITY DATA..............................................................................................................9 7 3.1. Acute Toxicity.................................................................................................................................9 8 3.2. Repeated-Exposure Toxicity............................................................................................................9 9 3.3. Developmental/Reproductive Toxicity..........................................................................................11 10 3.4. Genotoxicity...................................................................................................................................11 11 3.5. Chronic Toxicity/Carcinogenicity .................................................................................................11 12 3.6. Summary........................................................................................................................................12 13 4. SPECIAL CONSIDERATIONS........................................................................................................12 14 4.1. Metabolism and Disposition ..........................................................................................................12 15 4.2. Mechanism of Toxicity..................................................................................................................12 16 4.3. Structure Activity Relationships....................................................................................................12 17 4.4. Other Relevant Information ...........................................................................................................12 18 4.4.1. Species Variability.....................................................................................................................12 19 4.4.2. Susceptible Populations.............................................................................................................12 20 4.4.3. Time Scaling..............................................................................................................................13 21 5. DATA ANALYSIS FOR AEGL-1 ....................................................................................................13 22 5.1. Summary of Human Data Relevant to AEGL-1 ............................................................................13 23 5.2. Summary of Animal Data Relevant to AEGL-1............................................................................13 24 5.3. Derivation of AEGL-1 ...................................................................................................................13 Silicon Tetrafluoride INTERIM: 06-2008/ Page 5 of 26 1 6. DATA ANALYSIS FOR AEGL-2 ....................................................................................................13 2 6.1. Summary of Human Data Relevant to AEGL-2 ............................................................................13 3 6.2. Summary of Animal Data Relevant to AEGL-2............................................................................13 4 6.3. Derivation of AEGL-2 ...................................................................................................................14 5 7. DATA ANALYSIS FOR AEGL-3 ....................................................................................................14 6 7.1. Summary of Human Data Relevant to AEGL-3 ............................................................................14 7 7.2. Summary of Animal Data Relevant to AEGL-3............................................................................14 8 7.3. Derivation of AEGL-3 ...................................................................................................................14 9 8. SUMMARY OF AEGLS...................................................................................................................15 10 8.1. AEGL Values and Toxicity Endpoints ..........................................................................................15 11 8.2. Comparison with Other Standards and Guidelines........................................................................15 12 8.3. Data Adequacy and Research Needs .............................................................................................15 13 9. REFERENCES...................................................................................................................................16 14 APPENDIX A: DERIVATION OF AEGL VALUES...............................................................................17 15 APPENDIX B: DERIVATION SUMMARY FOR SILICON TETRAFLUORIDE AEGLS...................21 16 APPENDIX C: CATEGORY PLOT FOR SILICON TETRAFLUORIDE ..............................................25 17 Silicon Tetrafluoride INTERIM: 06-2008/ Page 6 of 26 1 LIST OF TABLES 2 3 TABLE 1. SUMMARY OF AEGL VALUES FOR SILICON TETRAFLUORIDE............................................7 4 TABLE 2. CHEMICAL AND PHYSICAL PROPERTIES....................................................................................8 5 TABLE 3. SUMMARY OF ANIMAL INHALATION TOXICITY DATA .........................................................11 6 TABLE 4. AEGL-1 VALUES FOR SILICON TETRAFLUORIDE ...................................................................13 7 TABLE 5. AEGL-2 VALUES FOR SILICON TETRAFLUORIDE ..................................................................14 8 TABLE 6. AEGL-3 VALUES FOR SILICON TETRAFLUORIDE ..................................................................15 9 TABLE 7. SUMMARY OF AEGL VALUES.........................................................................................................15 Silicon Tetrafluoride INTERIM: 06-2008/ Page 7 of 26 1 SUMMARY 2 3 Silicon tetrafluoride is a colorless, irritating gas with