APPENDIX D: HUMAN HEALTH RISK ASSESSMENT

156 Pages·2011·2.16 MB·English

Draft Battlement Mesa HIA, Revision 1 Conducted by
February 2011 Colorado School of Public Health

APPENDIX D: HUMAN HEALTH RISK ASSESSMENT
APPENDIX D
Appendix D Screening Level Human Health Risk Assessment February 2011
Battlement Mesa, Colorado Health Impact Assessment Colorado School of Public Health

Screening Level Human Health Risk Assessment
for Battlement Mesa Health Impact Assessment

Prepared by:
Lisa McKenzie, PhD, MPH
Roxana Witter, MD, MSPH
John Adgate, PhD, MSPH

February 2011

Contact: Lisa McKenzie PhD, MPH
Colorado School of Public Health
University of Colorado Denver
13001 East 17th Place
Aurora, Colorado 80045
[email protected]

University of Colorado Denver, Colorado School of Public Health, Denver, Colorado
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Appendix D Screening Level Human Health Risk Assessment February 2011
Battlement Mesa, Colorado Health Impact Assessment Colorado School of Public Health
Disclaimer
The research team that performed this work has no conflicts of interest to report, financial
or otherwise. The statements made in the Health Impact Assessment and Human Health
Risk Assessment are the work product of the authors and do not represent the position of
any university, private company, government agency, community group or any other
organization.
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Appendix D Screening Level Human Health Risk Assessment February 2011
Battlement Mesa, Colorado Health Impact Assessment Colorado School of Public Health
Acknowledgements
The authors of this report would like to thank the following groups for their helpful
assistance with this Human Health Risk Assessment: Garfield County Public Health for
their previous and continuing work to promote public health in their county and for
providing the numerous air studies they have conducted in the county and for the
assistance in identifying other studies used for this report; Colorado Department of Public
Health and Environment for their previous and continuing work in Garfield County and
throughout the state of Colorado and for their review of this HHRA; Antero Resources
for providing us with details of the natural gas project in Battlement Mesa and for
assistance with understanding how natural gas development and production processes
occur; the United States Geological Service for providing the database related to water
monitoring, as well as other technical materials; and Battlement Mesa Metropolitan
District for their assistance in understanding the water sources for the community.
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Appendix D Screening Level Human Health Risk Assessment February 2011
Battlement Mesa, Colorado Health Impact Assessment Colorado School of Public Health
TABLE OF CONTENTS

Summary of Modifications: .............................................................................................. 11
1 Introduction ................................................................................................................. 1
1.1 Site Description ................................................................................................... 2
1.1.1 Geology .............................................................................................................. 3
1.1.2 Population .......................................................................................................... 3
1.1.3 Economy ........................................................................................................... 4
1.1.4 Antero’s Proposed Plan............................................................................... 4
1.2 Previous Risk Assessments ................................................................................. 4
1.2.1 2002 Community-based Short-term Ambient Air Screening Study in Garfield
County for Oil and Gas Related Activities (CDPHE 2002) ....................................... 5
1.2.2 2005-2007 Garfield County Air Toxics Inhalation: Screening Level Human
Health Risk Assessment (CDPHE 2007) .................................................................... 5
1.2.3 2008 Community Health Risk Analysis of Oil and Gas Industry Impacts in
Garfield County, Colorado (Coons and Walker, 2008) ............................................. 6
1.2.4 2010 Garfield County Air Toxics Inhalation: Screening Level Human Health
Risk Assessment Inhalation of Volatile Organic Compounds Measured in 2008 Air
Quality Monitoring Study (CDPHE 2010). ................................................................ 7
2 Data Evaluation and Selection of COPCs ................................................................. 10
2.1 Sources of data .................................................................................................. 10
2.1.1 2005 to 2007 Garfield County Ambient Air Quality Study ............................ 10
2.1.2 2008 Garfield County Air Toxics Study ......................................................... 10
2.1.3 2008 to 2010 Garfield County Ambient Air Study ......................................... 11
2.1.4 2010 Antero Sampling .................................................................................... 11
2.1.5 2010 annual groundwater quality results – Battlement Mesa Water treatment
plant........................................................................................................................... 12
2.2 Sample Quantitation Limit Evaluation ............................................................. 12
2.2.1 2005 to 2007 VOC data ................................................................................. 12
2.2.2 2008 to 2010 data ........................................................................................... 13
2.2.3 Groundwater data ............................................................................................ 13
2.3 Data Reduction, Summary Statistics................................................................. 13
2.3.1 Duplicate Analyses ......................................................................................... 13
2.3.2 Summary Statistics of Sample Data ................................................................ 14
2.4 Background ....................................................................................................... 14
2.5 Selection of Contaminants of Potential Concern and Exposure Point
Concentrations .............................................................................................................. 15
2.5.1 Chemicals of Potential Concern Battlement Mesa Baseline Risk .................. 15
2.5.2 Bell-Melton Ranch Monitoring Station .......................................................... 16
2.5.3 Contaminants of Potential Concern Well Completion .................................... 16
2.5.4 Chemicals of Potential Concern Grab Samples .............................................. 17
2.6 Statistical Observations for Select COPCs ....................................................... 18
2.6.1 Comparison Between Ambient Air Samples and Well Completion Samples 18
2.6.2 Observed Temporal Trends............................................................................. 19
3 Exposure Assessment................................................................................................ 20
3.1 Potentially Exposed Populations....................................................................... 20
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3.2 Conceptual Site Model ...................................................................................... 20
3.3 Sources of potential contamination ................................................................... 21
3.4 Exposure Pathways ........................................................................................... 21
3.4.1. Complete Pathways ......................................................................................... 22
3.4.2 Potentially Complete Pathways ....................................................................... 22
3.5 Exposure Assumptions and Intake Equations ................................................... 23
3.5.1 All Resident Chronic Exposure Assumptions and Intake Equations .............. 23
3.5.2 All Residents Living Near Well Pads Chronic Exposure Assumptions and
Intake Equations ........................................................................................................ 25
3.5.3 All Residents Living Near Well Pads Subchronic Exposure Assumptions and
Intake Equations ........................................................................................................ 26
3.5.4 Child Resident Living Near Well Pad Acute Exposure Assumptions and
Intake Equations ........................................................................................................ 27
3.5.5 Adult Residents Living Near Well Pad Acute Exposure Assumptions and
Intake Equations ........................................................................................................ 28
4 Toxicity Assessment ................................................................................................. 30
4.1 Selection of Toxicity Values ............................................................................. 30
4.1.1 Cancer Toxicity Values................................................................................... 30
4.1.2 Non-Cancer Toxicity Values .......................................................................... 31
4.2 Summary of Health Effects of COPCs ............................................................. 32
4.2.1 Acetaldehyde.................................................................................................... 32
4.2.2 Benzene ........................................................................................................... 32
4.2.3 1,3-Butadiene .................................................................................................. 33
4.2.4 Chloroform ...................................................................................................... 33
4.2.5 Crotonaldehyde ................................................................................................ 34
4.2.6 1,4-Dichlorobenzene ....................................................................................... 34
4.2.7 Ethylbenzene ................................................................................................... 35
4.2.8 Formaldehyde ................................................................................................. 35
4.2.9 n-Hexane .......................................................................................................... 36
4.2.10 2-Hexanone .................................................................................................... 36
4.2.11 Methylcyclohexane ........................................................................................ 36
4.2.12 Methylene Chloride ...................................................................................... 37
4.2.13 n-Nonane ........................................................................................................ 37
4.2.14 n-Pentane........................................................................................................ 37
4.2.15 Toluene ......................................................................................................... 38
4.2.16 Trimethylbenzenes ......................................................................................... 38
4.2.17 Xylenes ......................................................................................................... 39
5 Risk Characterization ................................................................................................ 40
5.1 Risk Estimations ............................................................................................... 40
5.1.1 Cancer Risk Estimation................................................................................... 40
5.1.2 Non-Cancer Hazard Estimation ...................................................................... 41
5.1.3 Cumulative Risks for Multiple Chemicals ....................................................... 41
5.2 Baseline Risk in Battlement Mesa Before Implementation of Antero’s Project
42
5.2.1 Ambient Air Baseline Risk ............................................................................. 42
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5.3 Risk After Implementation of Antero’s Natural Gas Production Operations in
Battlement Mesa ........................................................................................................... 43
5.3.1 All Battlement Mesa Residents Chronic Risk ................................................ 43
5.3.2 Residents Living Near a Well Pad .................................................................. 45
5.3.3 Subchronic Hazard - Resident Living Near Well Pad .................................... 46
5.3.4 Acute Hazard - Child Living Near Well Pad .................................................. 47
5.3.5 Acute Risk – Adults and Elderly Adults Living Near Well Pad..................... 48
6 Uncertainty in Risk Assessment ............................................................................... 49
6.1 Uncertainties in Chemical Data ........................................................................ 49
6.1.1 Battlement Mesa Monitoring Station Data ..................................................... 49
6.1.2 Bell-Melton Ranch Monitoring Station Data .................................................. 50
6.1.3 Well Completion Data .................................................................................... 50
6.1.4 Data Collected with Noticed Odors at Residences .......................................... 51
6.1.5 Antero Sampling .............................................................................................. 52
6.1.6 Surface Water Run-off Data ............................................................................ 53
6.1.7 Background Data for Ambient Air ................................................................. 53
6.1.8 Groundwater Data ........................................................................................... 53
6.2 Uncertainty in Exposure Assessment ................................................................ 53
6.2.1 Potentially Complete Exposure Pathways Not Evaluated ............................... 53
6.2.2 Use of Bell-Melton Ranch Monitoring Station ............................................... 54
6.2.3 Use of Well Completion Samples ................................................................... 55
6.2.4 Use of EPA Default Exposure Factor Values ................................................ 55
6.2.5 Exposure Point Concentrations ....................................................................... 56
6.2.6 Exposures for Children .................................................................................... 56
6.2.7 Exposures for Elderly Adults .......................................................................... 57
6.3 Uncertainty in the Toxicity Assessment ........................................................... 57
6.3.1 Toxicity Values ............................................................................................... 57
6.3.2 COPCs without toxicity values ........................................................................ 59
6.3.3 Potential COPCs Not Measured...................................................................... 59
6.4 Uncertainty in Risk Estimation Due to Ozone and Particulate Matter ............. 60
6.5 Uncertainty in Risk Estimation Due to Chemical Mixtures .................................. 61
7 Summary and Conclusions ....................................................................................... 63
7.1 Summary ........................................................................................................... 63
7.2 Conclusions ....................................................................................................... 64
8 Key Data Gaps .......................................................................................................... 67
9 References ................................................................................................................. 69

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LIST OF TABLES

Table 2-1: Comparison of MRLs for 2005-2007 Data to EPA RSLs

Table 2-2: Comparison of MRLs from 2008 to 2010 Data to EPA RSLs

Table 2-3: Comparison of MRLs for Groundwater Data

Table 2-4: Summary Statistics and Selection of COPCs by Comparison to EPA RSLs
September to November 2010 Ambient Air Data Collected from Battlement Mesa

Table 2-5: Summary Statistics and Selection of COPCs by Comparison to EPA RSLs
2005 -2010 Ambient Air Data Bell-Melton Ranch Monitoring Station

Table 2-6: Summary Statistics and Selection of COPCs by Comparison to EPA Well
Completion Operations 2008, 2010

Table 2-7: Summary Statistics and Selection of COPCs by Comparison to EPA RSLs
Odor Events 2005 to 2007, 2010 Grab Samples

Table 2-8: Ambient Air Summary Statistics for Background Samples 2005 to 2008

Table 2-9: 95% UCLs and Selection of EPCs September to November 2010 Battlement
Mesa Monitoring Station

Table 2-10: 95% UCLs and Selection of EPCs for Bell-Melton Ranch Monitoring Station
2005 to 2010

Table 2-11: 95% UCLs and Selection of EPCs for Well Completion 2008 and 2010

Table 2-12: Comparison of Means between Well Completion Samples and Bell-Melton
Ranch Samples

Table 3-1: Cancer and Non-cancer Air Intake Values for Battlement Mesa Baseline Risk

Table 3-2: Cancer and Non-cancer Air Intake Values for Chronic and Subchronic
Exposures Bell-Melton Ranch

Table 3-3: EPCs and Surface Water Intakes for Acute Exposure of Child Resident

Table 4-1: Cancer and Non-cancer Inhalation Toxicity Values

Table 4-2: Contaminants of Potential Concern without Toxicity Values

Table 4-3: Oral/Dermal Non-cancer Toxicity Factors
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Battlement Mesa, Colorado Health Impact Assessment Colorado School of Public Health
Table 4-4: Target Organ/Systems for Non-cancer COPCs

Table 5-1: Baseline Risk Characterization for all Battlement Mesa Residents

Table 5-2: Comparison of EPCs to BTVs

Table 5-3: Chronic Risk Characterization for All Battlement Mesa Residents – 30 year
Duration

Table 5-4: Chronic Risk Characterization for Residents Living Near a Well Pad – 30
year Duration

Table 5-5: Subchronic Risk Characterization for All Residents Near a Well Pad – 20
month Duration

Table 5-6: Acute Risk Characterization for Child Resident Living Near a Well Pad – 7-
day Duration

Table 5-7: Acute Risk Characterization for Adult and Elderly Resident Living Near a
Well Pad – 7-day Duration

Table 6-1: Chemicals Identified from Antero’s MSDS

Table 7-1: Summary of Risk Characterization

LIST OF FIGURES

Figure 2-1: Temporal Trends of BTEX at Bell-Melton Ranch Monitoring Station – 2005
to 2010

Figure 2-2: Temporal Trends for Carbonyls Bell Melton Ranch Monitoring Station –
2008 to 2010

Figure 3-1: Conceptual Site Model for Battlement Mesa Health Impact Assessment

Figure 3-2: Domestic water supply and proposed well pad locations.

Figure 3-3: Locations of Baseline and Bell-Melton Ranch Monitoring Stations

Figure 7-1: Summary of Non-cancer Health Hazards

Figure 7-2: Summary of Excess Lifetime Cancer Risk

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Appendix D Screening Level Human Health Risk Assessment February 2011
Battlement Mesa, Colorado Health Impact Assessment Colorado School of Public Health
ACRONYMS

AI: air intake
Antero: Antero Resources Corporation
APCD: Air Pollution Control Division
AT: averaging time
ATSDR: Agency for Toxic Substances and Disease Registry
Bgs: below ground surface
BMC: Battlement Mesa Company
BTEX: benzene, toluene, ethylbenzene, and xylene
BTV: background threshold value
BW: body weight
CDPHE: Colorado Department of Public Health and Environment
cm2 : square centimeters
COGCC: Colorado Oil and Gas Conservation Commission
COPC: contaminant of potential concern
CSM: conceptual site model
DNPH: 2,4-dinitrophenylhydrazine
ED: exposure duration
EF: exposure frequency
ET: exposure time
EPA: United States Environmental Protection Agency
EPC: exposure point concentration
ERG: Eastern Research Group
GCPHD: Garfield County Public Health Department
HHRA: Human Health Risk Assessment
HI: hazard index
HIA: Health Impact Assessement
HQ: hazard quotient
IRIS: Integrated Risk Information System
kg: kilogram
IUR: inhalation unit risk
L: liter
MEI: maximum exposed individual
MRL: method reporting limit
NAAQS: National Ambient Air Quality Standard
NIOSH: National Institute of Occupational Safety and Health
PAH: polycyclic aromatic hydrocarbon
PAR: population attributable risk
PM: particulate matter
PM : particulate matter of 2.5 microns or less
2.5
PM : particulate matter of ten microns or less
10
ppb: parts per billion
ppm: parts per million
PPRTVs: Provisional Peer-Reviewed Toxicity Values
PRG: preliminary remediation goal
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