138
measured air emissions were identified as leakage from surface infrastructure, venting, and careless handling of produced hydrocarbons, not fracking (Pétron
et al. 2014).
The frack chemicals that may be responsible for detrimental human health
impacts are not well-known. A chemical must be both toxic and find an exposure
route to a person in order to have an actual health effect. The intensity of the effect
depends on the toxicity of the substance and whether the exposure was acute or
chronic, among other things. Health effects of chemical exposures are complicated,
and with fracking this is made even more so by the fact that a wide variety of chemical additives are used, many of which are new and proprietary.
The U.S. Environmental Protection Agency compiled a consolidated list of over
930 chemical compounds used or found in hydraulic fracturing fluid, including 132
chemicals present in flowback and produced water. Sources included federal and
state government documents and industry-provided data (USEPA 2016). Sorting
through these in terms of toxicology has been difficult. However, in actual practice,
only around half a dozen or so chemicals are used in a single frack stage, making
assessments much more reasonable for individual production sites (Soeder et al.
2014). The challenge is in knowing exactly what those chemicals are when the
industry is reluctant to release anything other than generic information.
As described back in Chap. 6, data on the chemical additives in hydraulic fracturing fluid can be found on the FracFocus website (http://fracfocus.org/). Common
substances added to frack fluid include methanol, isopropanol, crystalline silica,
2-butoxyethanol, ethylene glycol, hydrotreated petroleum distillates, sodium
hydroxide, hydrochloric (muriatic) acid, ammonium chloride, ammonium and
sodium persulfate, glutaraldehyde, and polyacrylamide (Soeder et al. 2014). Many
of these are unpleasant, some are downright hazardous, and more than a few will
vaporize or volatilize in air.
Many of the air quality investigations around fracking and production that were
discussed back in Chap. 5 were focused on trying to determine potential exposures
of nearby populations to airborne toxins. A typical study was the investigation by
Zielinska et al. (2014) on the Barnett Shale to identify emission sources and then
monitor the effects on a community. This study was limited to a small community
and only lasted a month. Measurements were too brief to capture chemical concentration variations by season, development phase, operator practice, or geographic
region and the study results have limited applicability. Other research investigating
potential human contact with frack-related chemicals includes models and measurements for exposure routes via inhalation, ingestion, and even skin adsorption among
drill rig workers. These studies are summarized in the hefty literature compilation
by HEI (2019).
It turns out that the way chemical exposure is measured in the body can also
influence the results. For example, chemicals like VOCs remain in the body for only
hours to days before being metabolized and excreted, generally in urine. Depending
on when the sample was collected, urine chemical concentrations may not reflect
the actual exposure. The chemicals measured in body excretions like urine are often
a breakdown product of the parent compound called a metabolite, and different
8 Impacts to Human Health and Ecosystems
measured air emissions were identified as leakage from surface infrastructure, venting, and careless handling of produced hydrocarbons, not fracking (Pétron
et al. 2014).
The frack chemicals that may be responsible for detrimental human health
impacts are not well-known. A chemical must be both toxic and find an exposure
route to a person in order to have an actual health effect. The intensity of the effect
depends on the toxicity of the substance and whether the exposure was acute or
chronic, among other things. Health effects of chemical exposures are complicated,
and with fracking this is made even more so by the fact that a wide variety of chemical additives are used, many of which are new and proprietary.
The U.S. Environmental Protection Agency compiled a consolidated list of over
930 chemical compounds used or found in hydraulic fracturing fluid, including 132
chemicals present in flowback and produced water. Sources included federal and
state government documents and industry-provided data (USEPA 2016). Sorting
through these in terms of toxicology has been difficult. However, in actual practice,
only around half a dozen or so chemicals are used in a single frack stage, making
assessments much more reasonable for individual production sites (Soeder et al.
2014). The challenge is in knowing exactly what those chemicals are when the
industry is reluctant to release anything other than generic information.
As described back in Chap. 6, data on the chemical additives in hydraulic fracturing fluid can be found on the FracFocus website (http://fracfocus.org/). Common
substances added to frack fluid include methanol, isopropanol, crystalline silica,
2-butoxyethanol, ethylene glycol, hydrotreated petroleum distillates, sodium
hydroxide, hydrochloric (muriatic) acid, ammonium chloride, ammonium and
sodium persulfate, glutaraldehyde, and polyacrylamide (Soeder et al. 2014). Many
of these are unpleasant, some are downright hazardous, and more than a few will
vaporize or volatilize in air.
Many of the air quality investigations around fracking and production that were
discussed back in Chap. 5 were focused on trying to determine potential exposures
of nearby populations to airborne toxins. A typical study was the investigation by
Zielinska et al. (2014) on the Barnett Shale to identify emission sources and then
monitor the effects on a community. This study was limited to a small community
and only lasted a month. Measurements were too brief to capture chemical concentration variations by season, development phase, operator practice, or geographic
region and the study results have limited applicability. Other research investigating
potential human contact with frack-related chemicals includes models and measurements for exposure routes via inhalation, ingestion, and even skin adsorption among
drill rig workers. These studies are summarized in the hefty literature compilation
by HEI (2019).
It turns out that the way chemical exposure is measured in the body can also
influence the results. For example, chemicals like VOCs remain in the body for only
hours to days before being metabolized and excreted, generally in urine. Depending
on when the sample was collected, urine chemical concentrations may not reflect
the actual exposure. The chemicals measured in body excretions like urine are often
a breakdown product of the parent compound called a metabolite, and different
8 Impacts to Human Health and Ecosystems