UNIVERSITY OF COLORADO | COLORADO STATE UNIVERSITY | UNIVERSITY OF NORTHERN COLORADO

Human Health Risks Associated with

Development of Unconventional

Natural Gas Resources Impact of Unconventional Natural Gas Drilling Operations on

the Environment and Public Health

February 18, 2014

Lisa M. McKenzie, PhD, MPH

Research Associate

Department of Environmental and Occupational Health

University of Colorado

Roadmap

• Human Health Risk Assessment of Air Emissions from Development of Unconventional Natural Gas Resouces (Mckenzie, Witter, Newman, Adgate, Science

of the Total Environment, 424, 2012)

• Birth Outcomes and Proximity of Maternal Residence to Natural Gas Development in Rural Colorado (McKenzie, Guo, Witter, Savitz,

Newman, and Adgate, EHP, Advanced Publication 2014).

Battlement Mesa

The proposal

Citizen Request

“On behalf of Battlement Mesa citizens, BCC

members have requested the county and state

to conduct a "Health Impact Assessment" (HIA)

before a Special Use Permit (SUP) is approved

to any company drilling within the Battlement

Mesa PUD.”

Battlement Concerned Citizens, November 6, 2009

Data Assessment – Mann-Whitney comparison

NGD Area and Well Completions

Chemical p-value

1,2,3-Trimethylbenzene 0.0501

1,2,4-Trimethylbenzene <0.001

1,3,5-Trimethylbenzene <0.001

1,3-Butadiene 0.996

Benzene <0.001

Cyclohexane <0.001

Ethylbenzene <0.001

Isopropylbenzene 0.251

Methylcyclohexane <0.001

m-Xylene/p-Xylene <0.001

n-Hexane <0.001

n-Nonane <0.001

n-Pentane 0.06

n-Propylbenzene 0.0501

o-Xylene <0.001

Propylene 0.991

Styrene 0.272

Toluene <0.001

Human Health Risk Assessment

• “Screening” Risk Estimates Using EPA methods – EPA Reference Concentrations (RfCs), inhalation unit risks, and other health-

based guidelines when RfCs or cancer potency estimates not available

– Exposure scenarios

– Chronic and subchronic assessments of risk for nearby residents

• Quantitative Risk Assessment – Non Cancer (Systemic): Hazard Index

• Ratio of estimated exposure to RfC and/or health-based guidance level

• Index sums potential effects of multiple chemicals

• Are these greater than 1?

– Cancer: Lifetime Excess Cancer Risk, multiple chemicals • Are risks greater than 1 in a million ?

• Are risks greater than 1 in 10,000 ?

Exposed Populations

Two Populations

– Residents living within the PUD at residence not near well pad.

– Residents living within the PUD at a residence near well pad.

– Divided exposures into “near” and “far” from well pads based on citizen

odor complaints • Residents living within ½ mile of a well pad were considered as living near a well pad

based on odor complaints filed with COGCC in July and August 2010 (COGCC 2010).

• Self reported eye irritation, breathing problems, coughing, and pneumonia

• COGCC confirmed the odor complaints

Exposure Scenarios

Site Specific Durations: Based on Operator’s Information

– Subchronic: Short-term, “high exposure” well completion scenario,

resident living near two well pads under development, 20 months total

• 2 weeks to complete each well

• 20 wells per pad

• 2 well pads

– Chronic: 30 year exposures to well production emissions/natural gas

area emissions, noncancer and cancer risk estimates • 5 years of well development (drilling and completions)

• 20 to 30 years of production

EPA Defaults for “reasonable maximum exposure”:

Frequency: 350 days/per year, 24 hours/day

Non-Cancer Hazard Indices by Duration

of Exposure and Distance from Source

0.4 0.2

1

5

0

1

2

3

4

5

6

Chronic, Far Subchronic, Far Chronic, Near Subchronic, Near

Hazard

In

dex

Exposure Scenario

Level above which health

effects may occur

Non-Cancer Hazard Indices by Health Endpoint:

Near Wells, 20 Month Exposure Scenario

4

2

3

1

0

1

2

3

4

5

Neurological Effects Respiratory Effects Hematogical Effects Developmental Effects

Hazard

In

dex

End Points

Excess Lifetime Cancer Risks

6 10

0

10

20

30

40

50

60

70

80

90

100

110

Residents > 1/2 mile Residents ≤ 1/2 mile

Excess C

an

cer

Ris

k p

er

on

e M

illio

n In

div

idu

als

Exposure Scenario

Summary of Excess Lifetime Cancer Risk

EPA's Target of 1 in a

million

Risk where EPA

requires remediation

Risk Assessment Uncertainties and

Limitations • Small sample size: limited data exists on emission

around well completion sites

• Non-methane pollutant emissions appear to vary substantially by field type, number of well heads, completion process, and controls in place

• Limited suite of volatile compounds explored, but not other primary or secondary pollutants (e.g., aldehydes, diesel exhaust, ozone, PM, etc.)

• These data do not tell us how far is far enough nor how close is too close to well development sites

Natural Gas Operations

Can emit many

chemicals

Directly

Diesel Engines

Toluene and xylene are

teratogens (agents that

cause birth defects)

Benzene is a mutagen

and a carcinogen

Cross the placenta

Historically as Close as 150

feet from residences.

Thousands of Rural Coloradoans Live in the

Vicinity of Natural Gas Operations

Retrospective Cohort Study

Explore the association between a mother’s

proximity to natural gas development while

pregnant and birth outcomes using:

• Birth certificate data

• Birth defects surveillance data

• Geocoded well locations

• Information on spud dates and gas production

The Cohort

• 124,832 infants born between 1996 and 2009

• Rural areas and towns with populations less than 50,000 (Denver-Metropolitan area, El Paso County and the cities of Fort Collins, Boulder, Pueblo, Grand Junction and Greely excluded)

• White Hispanic and Non-Hispanic Mothers

• Singleton live births

Located all gas wells that existed in the infant’s

birth year within 10 miles of where the mother was

living on the birth date of her infant

Ten Miles Ten Miles

Exposed Unexposed

Measured the distance of each gas well from the

Mother’s home

Inverse Distance Weighted Count

• Calculated the inverse distance weight for each

well

• Summed the inverse distance weights for wells

in the 10 radius around the mother’s home.

• The closer a well is to the home, the more

influence/weight it has in the count.

Tertiles

Exposed

Group

Low (1 to

3.62 wells

per mile)

High (126

to 1400

wells per

mile)

Medium

(3.63 to

125 miles

per mile)

Birth Outcomes

• Congenital Heart Defects

• Neural Tube Defects (anencephalus and spina bifida)

• Oral Clefts (cleft lip and cleft palate)

• Preterm birth (less than 37 weeks of pregnancy completed)

• Term Low Birth Weight (less than 2500 grams ~ 5 pounds)

Inverse Distance

Weighted Well Counta

0 Wells

within 10

Miles

Low Medium High Cochran-Armitage

Trend Test p-

valued

Live Births (N) 66,626 19,214 19.209 19,793

CHDs

Cases (N) 887 281 300 355

Crude OR 1 1.1 1.2 1.3 < 0.0001

Adjusted OR (95% CI)b 1.1 (0.93, 1.3) 1.2 (1.0, 1.3) 1.3 (1.2, 1.5)

NTDs

Cases (N) 27 6 7 19

Crude OR 1 0.77 0.90 2.4 0.01

Adjusted OR (95% CI)c 0.65 (0.25, 1.7) 0.80 (0.34, 1.9) 2.0 (1.0, 3.9)

Oral Clefts

Cases (N) 139 31 41 40

Crude OR 1 0.77 1 0.97 0.9

Adjusted OR (95% CI)b 0.65 (0.43, 0.98) 0.89 (0.61, 1.3) 0.82 (0.55, 1.2) aLow = first tertile, 1 to 3.62 wells per mile, medium = second tertile, 3.63 to 125 wells per mile, high = third tertile, 126 to 1400 wells per mile. bAdjusted for maternal age, ethnicity, smoking, alcohol use, education, and elevation of residence, as well as infant parity and gender. cAdjusted only

for residence elevation because of low numbers. dCochran-Armitage trend test performed as two tailed test on unadjusted logistic regression.

Inverse Distance Weighted Well Counta

0 Wells within 10

Miles

Low Medium High Cochran-Armitage Trend

Test p-valued Preterm Birth

Live Births (N) 65,506 18,884 18,854 19,384

Cases (N) 4,849 1,358 1,289 1,274

Crude OR 1 0.97 0.92 0.88 < 0.0001

Adjusted OR (95% CI)b 0.96 (0.89, 1.0) 0.93 (0.87, 1.0) 0.91 (0.85, 0.98)

Term Low Birth Weight

Full Term Live Births

(N)

60,653 17,525 17,565 18,104

Cases (N) 2,287 525 471 432

Crude OR 1 0.79 0.70 0.62 < 0.0001

Adjusted OR (95% CI)b 1.0 (0.9, 1.1) 0.86 (0.77, 0.95) 0.9 (0.8, 1)

Mean difference in birth weight (grams)c

0 5 (-2.2, 13) 24 (17, 31) 22 (15, 29)

aLow = first tertile, 1 to 3.62 wells per mile, medium = second tertile, 3.63 to 125 wells per mile, high = third tertile, 126 to 1400 wells per mile .

bAdjusted for maternal age, ethnicity, smoking, alcohol use, education, and elevation of residence, as well as infant parity and gender. cAdjusted

for maternal age, ethnicity, smoking, alcohol use, education, and elevation of residence, as well as infant parity, gender, and gestational age. dCochran-Armitage trend test performed as two tailed test on unadjusted logistic regression.

Limitations

• Undercounting of Birth Defect Outcomes

• Obscuring of Outcomes by Grouping

• Information on some potentially important

confounders not available (i.e. maternal folate

consumption)

• Exposure Misclassification

– Maternal residence during the first trimester

– Specific activities occurring at well sites

Conclusions

• Short term exposures to air emissions from well sites are potentially in the range of health concern for nearby residents

– Emissions include mutagens and teratogens (e.g. benzene, xylenes, and toluene)

– Health concerns include neurological, respiratory, and developmental effects.

– Much is dependent on distance, local meteorology and topography

• These results suggest a positive association between greater density and proximity of natural gas wells within a 10-mile radius of maternal residence and greater prevalence of CHDs and possibly NTDs, but not oral clefts, preterm birth, or reduced fetal growth.

• Further study is needed to address the limitations of this research

Why is this important? The Wall Street Journal estimates that over 15 million Americans live within one mile of an O&G well that was drilled after the year 2000 (Russell Gold October 25, 2013). Our results, results of other research teams, and the current trends in natural gas development underscore the importance of conducting more comprehensive and rigorous research on the potential health effects of natural gas (and oil) development using unconventional methods.

Acknowledgements • CSPH Colleagues: Roxana Witter, John Adgate, Lee Newman, Ruixen Guo,

David Savitz, Brown University

• Garfield County Public Health: Jim Rada, Paul Reaser, and GC BOCC funding

• Colorado Department of Public Health (CDPHE) and Environment’s Health Statistics and Colorado Responds to Children with Special Needs Sections provided outcome data for this study. CDPHE specifically disclaims responsibility for any analyses, interpretations, or conclusions.

• Additional funding from the Colorado School of Public Health Department of Environmental and Occupational Health

Garfield County Emissions Inventory

Prepared for Garfield County

Prepared by the Colorado Department of Public Health and Environment

Air Pollution Control Division

October 2009

Inverse Distance Weighted Well Counta 0 Wells within 10 Miles Low Medium High

Conotruncal Defects

Cases (N) 40 14 13 15

Adjusted OR (95% CI)c 1 1.1 (0.57, 2.2) 1.1 (0.55, 2.0) 1.2 (0.6, 2.2)

Ventricular Septal Defects

Cases (N) 210 68 59 84

Adjusted OR (95% CI)b 1 1.3 (0.96, 1.8) 1.1 (0.81, 1.5) 1.5 (1.1, 2.1)

Endocardial Cushion and Mitrovalve Defects

Cases (N) 39 14 12 12

Adjusted OR (95% CI)c 0.81 (0.42, 1.6) 0.80 (0.41, 1.5) 0.67 (0.33, 1.32)

Pulmonary Artery and Valve Defects

Cases (N) 137 52 62 66

Adjusted OR (95% CI)b 1 1.3 (0.89, 1.8) 1.5 (1.1, 2,1) 1.6 (1.1, 2,2)

Tricuspid Valve Defects

Cases (N) 9 5 8 8

Adjusted OR (95% CI)c 1 2.6 (0.75, 9.1) 3.9 (1.3, 11) 4.2 (1.3, 13)

Aortic Artery and Valve Defects

Cases (N) 75 22 21 24

Adjusted OR (95% CI)b 1 1.1 (0.68, 1.9) 1.0 (0.62, 1.8) 1.2 (0.73, 2.1)

Patent Ductus Arteriosis

Cases (N) 59 18 17 15

Adjusted OR (95% CI)b 1 1.0 (0.56, 1.8) 0.96 (0.55, 1.7) 0.83 (0.44, 1.5)

aLow = first tertile, 1 to 3.62 wells per mile, medium = second tertile, 3.63 to 125 wells per mile, high = third tertile, 126 to 1400 wells per

mile. bAdjusted for maternal age, ethnicity, smoking, alcohol use, education, and elevation of residence, as well as infant parity and gender. cAdjusted only for residence elevation of because of low numbers.