Exposure to Contaminants in Drinking Water

Risk Science Institute International Life Sciences Institute Washington, D.C.

1 Introduction -- References -- 2 Contaminant Characteristics -- 2.1 Introduction -- 2.2 Physical and Chemical Parameters -- 2.3 The Contaminants -- 2.3.1 Inorganics -- 2.3.2 Organics -- References -- 3 Exposure Characteristics -- 3.1 Demographics -- 3.1.1 Relationship to Activity Patterns and to Building and Water Source Characteristics -- 3.1.2 Selecting a Basic Demographic Group -- 3.1.3 Applicable Census Data and Survey Results -- 3.1.4 Representation of National vs. Local Population Groups -- 3.1.5 Characterization of Sensitive Populations -- 3.1.6 Data Gaps and Research Needs -- 3.2 Consumption and Time /Activity Data -- 3.2.1 Principal Activities -- 3.2.2 Indirect (Second-Hand) Exposures -- 3.2.3 Variation among Population Groups -- 3.2.4 Applicable Databases -- 3.2.5 Ongoing Studies -- 3.2.6 Data Gaps and Research Needs -- 3.2.7 Primary References -- References -- 3.3 Building Characteristics -- 3.3.1 Residence Types and Subtypes, and Their Volumes -- 3.3.2 Air Exchange Rates -- 3.3.3 Airflow Between Rooms and Zones -- 3.3.4 Key Factors Affecting Degree of Air Exchange and Airflow -- 3.3.5 Applicable References and Databases -- 3.3.6 Data Gaps and Research Needs for Building Characteristics -- 3.3.7 Additional Publication -- References -- 3.4 Water Source Characteristics -- 3.4.1 Analysis of System Components -- 3.4.2 Estimation of Source Water Quality -- 3.4.3 Data Gaps and Research Needs -- References -- 4 Developing Exposure Estimates -- 4.1 Introduction /Overview -- 4.1.1 Ingestion Exposure -- 4.1.2 Inhalation Exposure -- 4.1.3 Dermal Absorption -- References -- 4.2 Transfer of Volatile Compounds from Drinking Water to Indoor Air -- 4.2.1 Introduction -- 4.2.2 Henry’s Law and the Mass-Transfer Coefficient -- 4.2.3 Predicting Mass-Transfer Rates -- 4.2.4 Measuring Mass-Transfer Coefficients -- 4.2.5 Relationship between KqLA, KoLa, and TE -- 4.2.6 Nonideal Conditions -- 4.2.7 Current State of Knowledge -- 4.2.8 Future Work -- References -- 4.3 Aerosols and Water Droplets -- 4.3.1 Definitions (Aerosols, Droplets) -- 4.3.2 Water Uses as Sources of Droplets /Aerosols -- 4.3.3 Lifetime of Droplets and Aerosols -- 4.3.4 Integration of Processes -- References -- 4.4 Water (Direct Contact) -- 4.4.1 Principles -- 4.4.2 Chemical Characteristics -- 4.4.3 Knowledge Gaps -- References -- 4.5 Modeling of Exposure to Waterborne Contaminants -- 4.5.1 Introduction -- 4.5.2 Modeling Methods -- 4.5.3 Representation of Input Parameters -- 4.5.4 Knowledge Gaps -- References -- 5 Respiratory Uptake -- 5.1 Introduction -- 5.2 Regions of the Respiratory Tract -- 5.3 Models for Assessing Respiratory Dosimetry -- 5.4 Sources of Airborne Drinking Water Toxicants -- 5.4.1 Volatile Gases -- 5.4.2 Aerosols -- 5.4.3 Other Sources -- 5.5 Physiologic and Pharmacokinetic Factors -- 5.5.1 Respiratory Parameters -- 5.5.2 Other Factors -- 5.6 Model Estimates of Lung Toxicant Uptake -- 5.6.1 The Contribution of Shower Aerosols to Uptake -- 5.6.2 Comparison of Inhalation and Dermal Uptake -- 5.7 Summary -- References -- 6 Dermal Uptake -- 6.1 Introduction -- 6.1.1 Exposure to Vapors -- 6.1.2 Exposure to Aerosols -- 6.1.3 Exposure to Liquid Water -- 6.2 Barrier Properties -- 6.2.1 Fick’sLaw -- 6.2.2 Skin Structure -- 6.2.3 Regional Variation -- 6.2.4 Effect of Skin Damage -- 6.2.5 Effect of Temperature and Blood Flow Rate -- 6.2.6 Effect of Hydration -- 6.2.7 Effect of Soaps and Surfactants -- 6.2.8 Effect of Ionization -- 6.2.9 Consideration of Special Populations -- 6.2.10 Summary -- 6.3 Types of Skin Penetration Data -- 6.3.1 Ways to Express Penetration -- 6.3.2 Experimental Methods -- 6.3.3 Sources of Penetration Data -- 6.3.4 Correlations from Many Data Sets -- 6.4 Mathematical Models of Penetration -- 6.4.1 Membrane Models -- 6.4.2 Pharmacokinetic Models -- 6.5 Recommendations of Experimental Methods -- for Water Exposures -- 6.6 Recommendations for Use of Penetration Data -- for Risk Assessments -- References -- 7 Case Study -- 7.1 Introduction -- 7.2 Modeled Residence -- 7.3 Activity Patterns -- 7.4 Water Uses -- 7.4.1 Simulating Water Use Occurrences -- 7.4.2 Simulating Water Use Durations -- 7.4.3 Humidifier Water Uses -- 7.5 Modeling Contaminant Emissions During Household Water Uses -- 7.5.1 Volatilization Models -- 7.5.2 Model Inputs for Water-Using Devices -- 7.5.3 Aerosol Emissions -- 7.6 Modeling Absorbed Dose -- 7.6.1 Absorbed Dose due to Vapors -- 7.6.2 Absorbed Dose due to Aerosols -- 7.6.3 Absorbed Dose due to Dermal Contact -- 7.7 Results -- 7.7.1 Results of a Selected Case -- 7.7.2 Results of Population Dose Distribution -- 7.7.3 Discussion -- 7.8 Conclusions -- References -- Index.