An Exploratory Study of Air Quality Near Natural Gas Operations, authored by Colborn et al. and published in Human and Ecological Risk Assessment: An International Journal, was designed to assess air quality in Colorado an area where residences and gas wells co-exist.
The study measured airborne toxins at many stages of natural gas extraction operations.
The present study was designed to explore the presence of volatile chemicals, many of which are associated with the production of natural gas, in a rural natural gas production area for 1 year. The sampling period spanned the time before, during, and after development of a natural gas well pad. Development included drilling, hydraulic fracturing, and production operations. To our knowledge, no study of this kind has been published to date.
The study involved weekly air sampling over a one year period. Analysis
revealed that the number of non-methane hydrocarbons (NMHCs) and their concentrations were highest during the initial drilling phase and did not increase during hydraulic fracturing in this closed-loop system. Methylene chloride, a toxic solvent not reported in products used in drilling or hydraulic fracturing, was detected 73% of the time; several times in high concentrations.
A literature search of the health effects of the NMHCs revealed that many had multiple health effects, including 30 that affect the endocrine system, which is susceptible to chemical impacts at very low concentrations, far less than government safety standards. Selected polycyclic aromatic hydrocarbons (PAHs) were at concentrations greater than those at which prenatally exposed children in urban studies had lower developmental and IQ scores. The human and environmental health impacts of the NMHCs, which are ozone precursors, should be examined further given that the natural gas industry is now operating in close proximity to human residences and public lands.
The article, findings and implications, health effects references and a video can be downloaded from The Endocrine Disruption Exchange here.
FINDING: In this closed-loop system, the number and concentrations of chemicals detected was highest during the early stag e of drilling, and fracking events did not substantially alter the number or c oncentration of chemicals present.
IMPLICATION: This study demonstrates the need to focus on a new suite of toxic volatile chemicals, the NMHCs releas ed during drilling, that heretofore have received little attention.
FINDING: There can be large variations from week to week in the types and numbers of volatile chemicals detected.
IMPLICATION: Grab samples reveal what is in the air at a particular moment and cannot accurately represent the different chemicals that can be released during all stages of well development and producti on, or the range of their concentrations. Under-sampling could lead to false negative results.
IMPLICATION: To better interpret the results from systematic sampling, weather patterns and seasonal changes n eed to be measured (e.g. using wind roses). Sampling during seasons of low temperature and low wind velocity is particularly important in areas that are prone to inversions.
FINDING: Chemical concentrations were below federal exposure limits, but above concentrations found to have heal th effects in scientific studies.
IMPLICATION: Government standards do not ta ke into account low-level, chronic exposure experienced by the in creasing numbers of people in close proximity to gas operations. Some VOC s are endocrine disrupting chemicals, which can cause adverse effects at low-co ncentrations, even in parts per trillion, for which there are no government standards yet.
FINDING: Polycyclic aromatic hydrocarbons (PAHs), detected in parts per trillion, were at greater concentrations than were reported in urban studie s of prenatal exposure, in which adverse affects on fetal growth an d childhood cognitive development were demonstrated.
IMPLICATION: Concentrations of P AHs should be inve stigated in rural neighborhoods with and without natural gas activity.
FINDING: Methylene chloride was detected in 73% of the sample s, sometimes at extremely high concentrations, but was not liste d as an ingredient in any of the products reported in two lists of several hundred products used by the natural gas industry.
IMPLICATION: This suggests that it is time to require full disclosure for all toxic chemicals used during natural gas operations, including those that might only be used above ground.
Colborn et al also authored an earlier peer-reviewed study, Natural Gas Operations from a Public Health Perspective, also published in the peer-reviewed Human and Ecological Risk Assessment: an International Journal.