HUMAN HEALTH RISK ASSESSMENT (HHRA) FOR OFFSITE IMPACTS FROM TRAIL, B.C., SMELTER Phase 4—Additional Data Collection and Probabilistic Risk Calculations Prepared for Teck Cominco Metals Ltd. 25 Aldridge Avenue P.O. Box 1000 Trail, B.C. V1R 4L8 Prepared by 7900 SE 28th Street Suite 410 Mercer Island, WA 98040 August 12, 2008 Phase 4 HHRA Trail B.C. August 12, 2008 CONTENTS LIST OF FIGURES...................................................................................................................................vi LIST OF TABLES ................................................................................................................................... vii ACRONYMS AND ABBREVIATIONS...............................................................................................ix EXECUTIVE SUMMARY .......................................................................................................................xi 1 INTRODUCTION ...........................................................................................................................1‐1 1.1 SITE HISTORY AND PREVIOUS INVESTIGATIONS....................................................1‐1 1.2 OBJECTIVES OF THE PHASE 4 ASSESSMENT ..............................................................1‐2 1.3 RISK ASSESSMENT APPROACH......................................................................................1‐3 1.3.1 Risk Assessment Guidance Followed in Phase 4...............................................1‐4 1.3.2 Probabilistic vs. Deterministic Approaches........................................................1‐5 1.4 ORGANIZATION OF RISK ASSESMENT REPORT .......................................................1‐6 2 PROBLEM FORMULATION ........................................................................................................2‐1 2.1 PHASE 4 PATHWAY SCREENING ANALYSIS AND CONSTRUCTION OF CONCEPTUAL SITE MODELS..........................................................................................2‐1 2.2 DATA SUMMARY................................................................................................................2‐2 2.2.1 Data Quality ............................................................................................................2‐2 2.2.2 Data Adequacy .......................................................................................................2‐3 2.3 PHASE 4 CONTAMINANT DATA AND SCREENING PROCESS..............................2‐4 2.3.1 Soil Data...................................................................................................................2‐5 2.3.2 Outdoor Surface Dust Data.................................................................................2‐10 2.3.3 Indoor Dust Data..................................................................................................2‐11 2.3.4 Soil, Outdoor Dust, and Indoor Dust PCOCs ..................................................2‐11 2.3.5 Air Data..................................................................................................................2‐12 2.3.6 Beach Sediment Data ...........................................................................................2‐14 2.3.7 Fish Tissue Data....................................................................................................2‐14 2.3.8 Produce Data.........................................................................................................2‐17 2.3.9 Groundwater Chemistry Data............................................................................2‐17 2.3.10 Surface Water Chemistry Data ...........................................................................2‐18 2.4 PHASE 4 CONTAMINANT‐SPECIFIC CONCEPTUAL SITE MODELS...................2‐19 2.4.1 Summary of Exposure Scenarios for Phase 4 ...................................................2‐19 2.4.2 Residential Scenario .............................................................................................2‐19 2.4.3 Commercial Scenario ...........................................................................................2‐20 2.4.4 Agricultural Scenario ...........................................................................................2‐20 2.4.5 Recreational ATV/Dirt Bike Use.........................................................................2‐20 Integral Consulting Inc. ii Phase 4 HHRA Trail B.C. August 12, 2008 3 EXPOSURE ASSESSMENT...........................................................................................................3‐1 3.1 INTAKE ANALYSIS – GENERAL APPROACH AND ASSUMPTIONS .....................3‐1 3.1.1 Derivation of PCOC Concentration Distributions.............................................3‐3 3.1.2 Exposure Duration .................................................................................................3‐3 3.1.3 Body Weight............................................................................................................3‐4 3.1.4 Averaging Time ......................................................................................................3‐5 3.2 SOIL, INDOOR DUST, AND OUTDOOR DUST INGESTION......................................3‐5 3.2.1 Soil Ingestion Rates ................................................................................................3‐5 3.2.2 Fractional Intakes ...................................................................................................3‐7 3.2.3 Exposure Frequencies ............................................................................................3‐7 3.2.4 Relative Bioavailability..........................................................................................3‐8 3.3 INHALATION OF AMBIENT AIR ..................................................................................3‐13 3.3.1 Inhalation Rates ....................................................................................................3‐13 3.3.2 Exposure Frequencies ..........................................................................................3‐14 3.3.3 Exposure Times ....................................................................................................3‐14 3.4 INHALATION OF PARTICULATES – AGRICULTURAL...........................................3‐16 3.4.1 Inhalation Rate......................................................................................................3‐16 3.4.2 Particulate Concentration in Air ........................................................................3‐16 3.4.3 Exposure Frequency.............................................................................................3‐16 3.4.4 Exposure Time ......................................................................................................3‐17 3.5 CONSUMPTION OF HOMEGROWN PRODUCE........................................................3‐19 3.5.1 Produce Consumption Rates ..............................................................................3‐19 3.5.2 Exposure Frequency.............................................................................................3‐19 3.5.3 Fractional Intake ...................................................................................................3‐20 3.6 CONSUMPTION OF LOCALLY CAUGHT FISH .........................................................3‐21 3.6.1 Fish Consumption Rates......................................................................................3‐21 3.6.2 Exposure Frequency.............................................................................................3‐22 3.6.3 Fractional Intakes .................................................................................................3‐22 3.7 INCIDENTAL INGESTION OF SOIL – ATV/DIRT BIKE.............................................3‐23 3.7.1 Soil Ingestion Rates ..............................................................................................3‐23 3.7.2 Exposure Frequency.............................................................................................3‐24 3.7.3 Relative Bioavailability........................................................................................3‐24 3.8 INHALATION OF PARTICULATES – ATV/DIRT BIKE..............................................3‐25 3.8.1 Inhalation Rates ....................................................................................................3‐25 3.8.2 Particulate Concentration in Air ........................................................................3‐25 3.8.3 Exposure Times ....................................................................................................3‐26 Integral Consulting Inc. iii Phase 4 HHRA Trail B.C. August 12, 2008 3.8.4 Exposure Frequencies ..........................................................................................3‐26 4 TOXICITY ASSESSMENT ............................................................................................................4‐1 4.1 TOXICITY VALUES..............................................................................................................4‐1 4.1.1 Noncancer Effects...................................................................................................4‐2 4.1.2 Carcinogenic Effects...............................................................................................4‐2 4.2 ANTIMONY TOXICITY SUMMARY ................................................................................4‐3 4.2.1 Toxicokinetics..........................................................................................................4‐3