Assessing Potential Unconventional Natural Gas Drilling-Related Residential Exposures

摘要

Unconventional natural gas drilling (UNGD), an industry currently impacting areas all over the U.S., often occurs close to residential areas. Few studies regarding the potential for chemical exposure and health impacts on people living near UNGD have been conducted. We monitored air and water from 14 residences in 4 different counties of southwest PA in the summer of 2013. Inclusion criteria were non-smoking households that utilized ground water as their primary water source. UNGD-proximate residences (n=11) were located ＜ 0.5 miles of a UNGD facility, and control homes (n=3) were located ＞ 3 miles from any drilling-related facility. Half of the UNGD-proximate homes had previously self-reported adverse health complaints, which residents attributed to UNGD. Questionnaires assessing demographics, household activities related to air quality, and perceived stress levels were administered at time of monitoring. Indoor and outdoor PM_(2.5) in UNGD-proximate homes ranged from 5.1 - 21.5 and 9.3 -19.8 μg/m3, respectively. PM2.5 levels were comparable to those observed in control homes and none exceeded 35 μg/m3, our "criteria of concern". Indoor NO2 (13.2 ± 4.0 ppb, mean + SEM), outdoor NO_2 (7.1 ± 0.5 ppb), and outdoor O_3 (25.5 ± 2.8 ppb) at UNGD homes were below our criteria of concern. Thirty-five percent of all the sampled homes contained at least one VOC ＞ than the 90th percentile seen in previous EPA studies. Twenty-two percent of UNGD-proximate homes and 33% of control homes revealed concentrations of benzene, toluene, ethylbenzene, and xylenes ＞ 90th percentile value reported. Water tests showed a wide variation in metal content, but none exceeded a primary minimum containment level (MCL) for any metal and no UNDG-dependent differences between homes were apparent. Methane, ethane, and ethylene in water from all homes were below the U.S. Dept.of Interior Federal Standard (10-28 μg/L). Our pilot results will guide and inform future exposure assessment strategies.