Evaluation of Airborne Exposures During Oil and Gas Exploration and Production:

Current Data and Considerations for Future Studies

Michael Berg, Ph.D.

Center for Toxicology and Environmental Health, L.L.C.

Little Rock • Houston • New Orleans • Memphis • Denver • Albany • Seattle

Public Concerns about Hydraulic Fracturing

1. Groundwater • Methane • Hydraulic fracturing chemicals

2. Air • Point source emissions during drilling, completion, and

fracturing • Field-wide emissions – ozone, GHGs

3. Soil/Surface Water • Spills on-site • Contamination through earthen pits

“What happens if the air is so bad that I have to close all my windows and shut off my swamp cooler”

Draft Battlement Mesa HIA, 2010

PUBLIC CONCERNS ABOUT AIRBORNE CONTAMINANTS

“Although the location of the Erie well meets…there was a great deal of concern from the community regarding potential air emissions of organic compounds”

CDPHE, 2012

“In response to residents’ concern about unpleasant sulfur-like odors, the Town of DISH hired a consultant to conduct air quality tests…”

TxDSHS, 2010

Fracking Protesters

DEVELOPMENT AND PRODUCTION

General Stages of Development 1. Pad Site Development 2. Vertical Drilling 3. Horizontal Drilling 4. Hydraulic Fracturing 5. Flowback and Completion

POTENTIAL EMISSIONS SOURCES • Vehicular traffic • On-site equipment • Produced fluids and gasses (formation depend.) • Flowback • Proppants • Condensate Tanks • Flaring

POTENTIALLY EMITTED COMPOUNDS • Volatile Hydrocarbons (BTEX, Alkanes) • Aldehydes (Acrolein, Formaldehyde, Acetaldehyde) • Alcohols (Methanol) • Oxides (NOx, SOx) • PAHs • Diesel Exhaust • Silica

Difficulty linking ambient air compounds to O&G Operations

GENERAL AIR MONITORING STUDIES

• Identify Sampling Location – Area or Localized Sampling Stations

• Collect Data – Establish Sampling Frequency and Duration

• Compare Data to Screening Values – E.g. RfCs, MRLs, Cancer Risk Estimates

Overall, topic has not been thoroughly studied

BARNETT SHALE

US Energy Administration Information

BARNETT SHALE AIR • Twelve12 auto GC monitors in the Barnett shale

area • Take air samples every hour for 23 hours a day for

over 40 VOCs, and post the results on the TCEQ website

• These air monitors have collected well over 100,000 air samples.

• TCEQ states that the data are showing “no levels of concern for any chemicals”

NORTH TEXAS AIR

MONITORING NETWORK

http://www.tceq.state.tx.us/assets/public/implementation/barnett_shale/bs_images/bsMonitors.png

http://www.tceq.state.tx.us/assets/public/implementation/barnett_shale/bs_images/autoGCbenzene.pdf

SHALE GAS OPERATIONS AND HUMAN HEALTH RISKS BUNCH ET AL. (2014)

Data Collection

• Acquired data from 7 TCEQ air monitoring stations in Barnett Shale.

• Two different types of monitoring stations

• Automated gas-chromatography (1hr.) – 46 VOCs

• Canister samples (24 hr., 6/d) – 105 VOCs

• Total of 4.6 million data points

Human Health Evaluation

• Receptor located directly at air monitoring station

• Data compared to hierarchy of health- and odor-based AMCVs

• Quantitative risk assessment

Results & Conclusions

• High frequency of detection (63 – 100 %) for 6 shale-gas associated VOCs

• One exceedence (0.00002 %) of odor-based AMCV was observed

• No acute AMCVs exceedences observed

• One VOC’s annual average exceeded chronic AMCV

• 1,2-dibromoethane

• Used as lead scavenger in fuels

• Average driven by detection limit

• Risks Assessment for shale-gas associated VOCs

• Hazard Index below 1.0

• Lifetime cancer risks within acceptable range (10-4 to 10-6)

SHALE GAS OPERATIONS AND HUMAN HEALTH RISKS BUNCH ET AL. (2014)

DISH, TX

This area of Texas has seen a large increase in natural gas development in the

past 10 years.

Located in Denton Co.

• Many Influences on Air Quality – Natural gas operations – Dallas/Ft Worth metro area

• High level of community concern for airborne emissions and human health – Non-specific symptomology (headaches,

respiratory problems, itchy and water eyes and other allergy-type symptoms

DISH, TX

DISH, TEXAS EXPOSURE

INVESTIGATION • May 12, 2010 - Texas

Department of State Health Services

• Collected blood and urine samples from 28 people living in and near the town of Dish.

• The blood samples analyzed for VOCs and compared U.S. population.

DISH, TEXAS EXPOSURE INVESTIGATION CONCLUDED:

– Pattern of VOC values in blood samples not consistent with a community-wide exposure such as those that might be associated with natural gas drilling operations.

– Other sources of exposure explain many of the findings. Elevated levels of BTEX associated with cigarette smokers.

• Used HHRA techniques to support a Health Impact Assessment in response to community petition to O&G development.

• Assumptions used in this assessment are controversial and overestimate risk.

AIR ASSESSMENTS IN GARFIELD COUNTY, CO

HHRA AND UNCONVENTIONAL NGD MCKENZIE ET AL. (2012)

• Proposed to evaluate health risks for residents located: • ≤ 0.5 miles from well pad • > 0.5 miles from well pad

MCKENZIE ET AL. (2012)

HHRA AND UNCONVENTIONAL NGD MCKENZIE ET AL. (2012)

• Concludes that non-cancer risks (neurological, respiratory, and developmental) are highest for residents who live within 0.5 miles of a well.

• Cancer risks are on the low end of the range used by

the USEPA to manage human health risks.

• Extrapolation of air results • Time to drill and complete well • Exposure Frequency and Duration

• Meteorological Conditions • Alternate sources • Changing O&G Procedures

Assumptions

THE TOWN OF ERIE, CO

www.HCN.org

• ~19,000 residents • Concern for O&G

development near residences and schools

• CDPHE conducted “snapshot” evaluation in summer of 2012.

• Air monitoring conducted during completion activities

• Sites employing “Green” completions.

THE TOWN OF ERIE, CO • Concentration of alkanes (e.g. methane, ethane, propane) at

monitoring site slightly higher than downtown Denver

• Concentrations of benzene and toluene were well within acceptable limits for human health.

• Likely that alternate sources contribute to detected compounds.

CDPHE, 2012

MARCELLUS SHALE PLAY • Located in the North East

• Most expansive shale gas play

• Covers ~ 95,000 square miles

• One of the most active plays in the US.

• Large expanse in O&G development since 2007

MARCELLUS SHALE WEST VIRGINIA

• DEP issued “Air Quality Report” in Summer of 2013 • Highlights the fact that while air studies performed

elsewhere may be useful for trend analysis, there are limitations transferring conclusions from one region to another.

• Outlines the results from two WV studies • Skyline Elementary • Noise, Light, Dust, and VOC Report

MARCELLUS SHALE PENNSYLVANIA

• Multiple short-term screening assessments

• Assessments limited in scope and duration

• 4 – 5 sampling weeks

• Compressor stations, well sites, fracking Sites, background sites

• Conducted a non-cancer screening level assessment

MARCELLUS SHALE PENNSYLVANIA

• Concentration of natural gas constituents detected (methane, ethane and propane, BTEX)

• Results indicate that while certain compounds (e.g. methyl mercaptan) were detected at levels which generally produce odors, air sampling did not identify concentrations of any compound that would likely trigger air-related health issues. PA DEP, 2010; 2011

MARCELLUS SHALE SOUTHWESTERN PENNSYLVANIA

REGIONAL VARIABILITY IN AIR CONCERNS

• Areas in Wyoming and Utah have experience elevated levels of ground-level ozone.

• Ozone is naturally present in the atmosphere, but concerns arise when present at ground level at elevated concentrations.

• Ground level ozone can form as a secondary reaction product between VOCs, NOx, and sunlight.

UINTAH BASIN OZONE

• Concentrations of ozone (O3) in the winter months are often in excess of 75 ppb.

• VOC and NOx emissions are ozone precursors. • O3 levels driven partly by meteorological conditions.

• Snow Cover • Temperature Inversions • Wind Patterns

GROUND-LEVEL OZONE AND CLINIC VISITS SUBLETTE COUNTY, WY

• Evaluated possible associations between short-term changes in ground-level ozone and adverse acute respiratory effects.

• Results suggest a 3% increase in clinic visits for respiratory related effects for every 10 ppb increase in 8-hr max ground ozone on the subsequent day.

COMMUNITY AIR STUDY CONSIDERATIONS

• Identification of Chemicals of Potential Concern • COPCs dependent upon formation or site activities • Which chemicals have the greatest potential to travel offsite? • Which chemicals are of greatest toxicity?

• Selection of Sampling Locations • Where are the relevant receptors located? • Sampling height for health evaluation purposes?

COMMUNITY AIR STUDY CONSIDERATIONS

• Identification of Potential Alternate Sources • Are there any industrial facilities, highways, etc. nearby ?

• Exposure Parameters • What is the length of on-site activities? • Frequency and Duration

• Meteorological Conditions • Collection and evaluation of wind data?

CONCLUSIONS • One-size fits all approach to air monitoring at

well sites is unlikely. • Current research does not demonstrate

widespread impacts to air resources. • Health impacts are unlikely due to the nature

of the process and the short duration of exposure.

• Further, high-quality research on this topic is warranted.

Thank You

Center for Toxicology and Environmental Health, L.L.C.

Little Rock • Houston • New Orleans • Memphis • Denver • Albany • Seattle

HHRA AND UNCONVENTIONAL NGD MCKENZIE ET AL. (2012)

Data Collection

• Ambient air samples (n=163) in midst of rural home sites and ranches

• Well completion site samples (n=24) collected 130 to 500 ft. from center of well-pad. At least one of these was during uncontrolled flowback.

Human Health Evaluation

• Risks supposedly evaluated for residents ≤ 0.5 mi from wells (nearest) or > 0.5 mi (distant) from wells.

• Risks from distant wells evaluated using ambient area samples only

• Risks from nearest wells evaluated using combination of well-pad and ambient area samples

Results & Conclusions

• Non-cancer risks highest for residents ≤ 0.5 mi from well.

• Subchronic HI > Chronic HI

• Non-cancer effects are neurological, respiratory, hematologic and developmental and driven by trimethylbenzene, aliphatic hydrocarbons, and xylenes.

• Cancer risks ranged from 6E-06 (distant) to 1E-05 (nearest)

• Benzene and 1,3 – butadiene, and ethylbenzene were primary contributors

• Further research required

• Prospective medical monitoring and surveillance

HHRA AND UNCONVENTIONAL NGD MCKENZIE ET AL. (2012)

THE HYDRAULIC FRACTURING PROCESS

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