137
Other important factors in health risks are the medium of exposure, and the exposure route. There are four major exposure routes for toxins to enter the body: inhalation, ingestion, absorption through the skin (dermal contact), and injection (directly
into the bloodstream). If the exposure medium for the toxin is in air, it is likely to be
inhaled. If it is in water or soil, it might be ingested, or absorbed through the skin.
Exposures to chemicals may be either chronic or acute, and both have risks. A
chronic, long-term exposure to a low chemical concentration can harm health differently but no less certainly than a brief, acute exposure to a high chemical
concentration.
The final critical risk factor is the exposed population. This makes a huge difference in how people react to toxins, and as we have seen, to pathogens in the age of
COVID. Children are usually the most sensitive to chemical exposures, because of
their smaller body sizes. Older people are also at higher risk, because of possible
complications from other ailments. Pregnant women make up a third high-risk
group because any toxin that can cross the placenta may affect the unborn child.
Healthy, young adults are usually considered the lowest-risk population, although
there are some toxins and pathogens (such as the 1918 influenza outbreak) that target this particular age group as well (HEI 2019).
The air transmission route appears to be favored by many health researchers as
the most likely exposure pathway for fracking-related health risks. Water may also
be a critical path, but chemical spills or leaks somehow have to make it into drinking
water supplies and then be ingested to pose a human health hazard. Air seems to be
a more likely path because everyone has to breathe.
Air transmission has a complication because many of the chemicals and compounds researches are trying to trace, such as VOCs, NOx, methane, and other airborne vapors and gases are emitted from both unconventional and conventional oil
and gas production, as well as many other sources. Linking a particular emission to
fracking can be impossible, because emissions from conventional wells are often
more intense than those from horizontal shale wells. Because the spacing between
adjacent, conventional vertical wells is much less than that of horizontal wells (refer
back to the discussion in Chap. 7), the air emissions from conventional wells are
often far more concentrated. If both types of wells are in the same or adjacent areas,
emissions from “fracking” might not actually be from fracked wells at all.
Conventional wells also tend to be older, leading to a greater risk of leaks from
deterioration of cement or casing.
As an example, a detailed air quality study on oil and gas operations in the
Denver-Julesburg basin in Colorado found some of the highest VOC emissions
coming from the Wattenberg Field on the western side of the basin near the city of
Denver (Pétron et al. 2014). This is a large conventional gas field discovered in
1970, and it produces gas and condensate out of the Niobrara Formation from
mostly vertical wells (Matuszczak 1973). At the time of the air quality study, most
of the horizontal drilling and multi-stage fracking operations in the D-J basin were
being done far to the northeast, in Pawnee National Grassland near the town of
Raymer. Although many of the vertical wells in the Wattenberg Field had been stimulated with single-stage hydraulic fracturing treatments, the sources for the
8.1 Human Health
Other important factors in health risks are the medium of exposure, and the exposure route. There are four major exposure routes for toxins to enter the body: inhalation, ingestion, absorption through the skin (dermal contact), and injection (directly
into the bloodstream). If the exposure medium for the toxin is in air, it is likely to be
inhaled. If it is in water or soil, it might be ingested, or absorbed through the skin.
Exposures to chemicals may be either chronic or acute, and both have risks. A
chronic, long-term exposure to a low chemical concentration can harm health differently but no less certainly than a brief, acute exposure to a high chemical
concentration.
The final critical risk factor is the exposed population. This makes a huge difference in how people react to toxins, and as we have seen, to pathogens in the age of
COVID. Children are usually the most sensitive to chemical exposures, because of
their smaller body sizes. Older people are also at higher risk, because of possible
complications from other ailments. Pregnant women make up a third high-risk
group because any toxin that can cross the placenta may affect the unborn child.
Healthy, young adults are usually considered the lowest-risk population, although
there are some toxins and pathogens (such as the 1918 influenza outbreak) that target this particular age group as well (HEI 2019).
The air transmission route appears to be favored by many health researchers as
the most likely exposure pathway for fracking-related health risks. Water may also
be a critical path, but chemical spills or leaks somehow have to make it into drinking
water supplies and then be ingested to pose a human health hazard. Air seems to be
a more likely path because everyone has to breathe.
Air transmission has a complication because many of the chemicals and compounds researches are trying to trace, such as VOCs, NOx, methane, and other airborne vapors and gases are emitted from both unconventional and conventional oil
and gas production, as well as many other sources. Linking a particular emission to
fracking can be impossible, because emissions from conventional wells are often
more intense than those from horizontal shale wells. Because the spacing between
adjacent, conventional vertical wells is much less than that of horizontal wells (refer
back to the discussion in Chap. 7), the air emissions from conventional wells are
often far more concentrated. If both types of wells are in the same or adjacent areas,
emissions from “fracking” might not actually be from fracked wells at all.
Conventional wells also tend to be older, leading to a greater risk of leaks from
deterioration of cement or casing.
As an example, a detailed air quality study on oil and gas operations in the
Denver-Julesburg basin in Colorado found some of the highest VOC emissions
coming from the Wattenberg Field on the western side of the basin near the city of
Denver (Pétron et al. 2014). This is a large conventional gas field discovered in
1970, and it produces gas and condensate out of the Niobrara Formation from
mostly vertical wells (Matuszczak 1973). At the time of the air quality study, most
of the horizontal drilling and multi-stage fracking operations in the D-J basin were
being done far to the northeast, in Pawnee National Grassland near the town of
Raymer. Although many of the vertical wells in the Wattenberg Field had been stimulated with single-stage hydraulic fracturing treatments, the sources for the
8.1 Human Health