Estudio de tomografía de resistividad eléctrica (TRE)

The results presented in this chapter showed that CSG area hospitalisation rates due to any cause increased significantly during the study period compared to both the CM and RA areas. Very few UNGD-related studies have examinedhospitalisation rates. One study examined all-age hospitalisation rates for

all-cause admissions across four counties with varying degrees of UNGD in the USA (Coons & Walker, 2008). Garfield County, the county with the highest level of UNGD, had the lowest or second lowest rate of all-cause hospitalisations; however, this was over a 6.25-year study period (Coons & Walker, 2008), compared to the 17-year period used in this thesis.

Comparing the age-standardised hospitalisation rates where significant increases over time occurred in the CSG area relative to the CM or RA areas with the potential changes that might be expected as identified in the previous literature (Table 6.5), ‘Infectious disease’, ‘Neoplasms’, ‘Ear’-related outcomes, ‘Genitourinary’-‘Ear’-related outcomes, and ‘Injuries’ were referenced in the literature as potential health outcomes. The estimates for a number of these outcomes (‘Neoplasms’, ‘Ear’, and

‘Injuries’) showed hospitalisation rates increased over time in the CSG area compared only to the CM area, and estimates for ‘Infectious disease’-related outcomes increased over time in the CSG area compared only to the RA area. Therefore, these were not the strongest observations noted for all-age hospitalisation rates because increases over time occurred in the CSG area relative only to the CM area and not to the RA area or vice versa. However, ‘Genitourinary’-related hospital admission rates increased in the CSG area compared to the CM and RA study areas over time, with modest estimates.

Although ‘Genitourinary’-related hospital admission rates were found to increase in the CSG area compared to both study areas, there are few studies that have actually discussed such outcomes. Navi et al. (2014) raised issues about health outcomes that would fall in this ICD chapter; however, the discussion was general and such health outcomes were not actually studied in the context of UNGD. There are concerns surrounding leaching of toxic organics from coal deposits into water and the potential for nephrotoxicity (Navi et al., 2014), but this has only been studied in areas where Balkan Endemic

Nephropathy is present, as well as certain areas in the United States (Feder et al., 2002; Finkelman et al., 2002; Orem, Tatu, Lerch, et al., 2007; Orem et al., 2014). Sub-chapters within this ICD chapter would have to be examined further to determine if there are increases for certain outcomes.

The ‘Infectious disease’ ICD chapter includes ‘Certain zoonotic bacterial diseases’, ‘Infections with a predominantly sexual mode of transmission’, ‘Arthropod-borne viral fevers’, and ‘Rickettsioses’, amongst others. As outlined in Chapter 2, vector-borne disease has been discussed in terms of UNGD and increasing water bodies (Zou et al., 2006). Increases in rates of STIs have also been discussed in terms of impacts as a result of UNGD (Coons & Walker, 2008; Goldenberg, Shoveller, Koehoorn, & Ostry, 2008;

Witter et al., 2013; Witter et al., 2011). However, the results presented here need to be examined further by sub-chapters within the main ICD chapter headings to determine what type of admissions show this increasing trend and if there are increasing trends for certain age groups.

Sub-chapters within the ‘Ear’ disease-related ICD chapter include ‘Diseases of external ear’,

‘Diseases of middle ear and mastoid’, ‘Diseases of inner ear’, and ‘Other disorders of ear’. UNGD studies have discussed health impacts in terms of ear-related symptoms that residents have reported (e.g., ringing in the ears, hearing loss) (Steinzor et al., 2013; Subra, 2009, 2010), potential impacts associated with noise pollution (Adgate et al., 2014; Witter et al., 2013), or noise/nuisance issues (Ferrar et al., 2013;

Korfmacher et al., 2014). Some studies have pointed out that UNGD can generate additional noise due to

truck traffic and heavy equipment, compressor stations, construction activities, and drilling and

completion operations (Adgate et al., 2014; Ferrar et al., 2013; Lechtenböhmer et al., 2011; University of Maryland, 2014; Witter et al., 2013), but there are no epidemiological studies that have examined health outcomes associated with noise resulting from UNGD (University of Maryland, 2014).

Potential impacts associated with environmental noise include cardiovascular health impacts, sleep disturbance, fatigue, changes in levels of annoyance, stress, headaches, and impacts on children’s

cognitive performance (enHealth, 2004; Stansfeld & Matheson, 2003; University of Maryland, 2014;

Witter et al., 2013). Such impacts may not necessarily manifest as hospital admissions within the ‘Ear’

disease-related ICD chapter and may not be severe enough for a person to present to hospital for admission.

While ‘Neoplasms’ admission rates increased over time in the CSG area compared to the CM area, it is difficult to draw any conclusions with respect to possible changes in environmental exposures due to the fact that neoplasm trends typically reflect events 10-20 years prior to manifestation and/or are due to cumulative lifetime exposures (Coons & Walker, 2008). It should be noted that any short-term trends might not be reflective of changes in the environmentally-related health hazard impact potential of CSG development. Changes in the rate of hospitalisation for ‘Neoplasms’ can also be an artefact of changes in screening practices (Coons & Walker, 2008); therefore, the noted differences or similarities between the CSG and CM or RA areas could be due to changes in health services, or they could be due to other factors that were not explored here.

Likewise, in examining CSG production as discussed in the Introduction, lag periods must be considered for any ‘Neoplasms’-related diagnoses. CSG production and well development activity only began a consistent increase in 2005/2006 (as shown in Figure 6.9), with both CSG production and well development activity showing a similar pattern. Considering a very conservative lag period of four years (Goldstein & Malone, 2013) means that the ‘Neoplasms’ data presented here could only be reflective of any changes after this period, with manifestation of disease after 2009/2010, if the ‘Neoplasm’-related diagnoses are related to any exposures associated with CSG development. However, considering typical lag periods, it is likely that such diagnoses would appear after the end of this study time period (post-2011).

Figure 6.9. Queensland coal seam gas (CSG) production and well development over the study period (1995-2011).

Stronger evidence was observed for all-ages health consequences related to ‘Blood/immune’ and

‘Eye’ diseases. Increases during the study period in hospitalisations due to these conditions were significantly higher in the CSG area compared to both the CM and RA areas. None of these categories were identified in the literature as potential health concerns due to UNGD. All-age RR estimates were greatest for ‘Blood/immune’ disease-related admissions in the CSG area; however, over the total study period in each area, ‘Blood/immune’ admissions accounted for only 1.01%, 0.52%, and 0.79% of each area’s respective total admissions for the CSG, CM, and RA areas.

It is difficult to compare these results with those discussed in previous literature. In the study by Coons & Walker (2008), diagnostic-related groupings (DRG) were used to classify hospital admissions, whereas ICD coding was used in the current programme of work, so the results are not comparable across all categories. For example, Coons and Walker have no equivalent for the ‘Blood/immune’ category used here, only a ‘Red cell/clotting’ DRG category, which showed that Garfield County’s rates decreased steadily over time. This contradicts the ‘Blood/immune’ disease findings presented in this chapter.

Diseases from this ICD chapter (e.g., anaemia and other blood disorders) have been discussed in the UNGD literature in relation to worker health and exposure to benzene, toluene, ethylbenzene, and xylene (Adgate et al., 2014); however, discussion is lacking in terms of community health. Generally, long-term exposure to benzene most often affects the blood and the immune system (Agency for Toxic Substances and Disease Registry, 2007), for which such outcomes are found in the ‘Blood/immune’

chapter. The most common route of exposure is through inhalation, typically through air contaminated by motor vehicle emissions and industrial use, as well as cigarette smoke (Leusch & Bartkow, 2010). While benzene, toluene, ethylbenzene, and xylene compounds are naturally occurring and can be found in some

water sources, the Queensland Government now has laws in place that ban the use of such compounds in hydraulic fracturing fluids (Queensland Government, 2013i).

Likewise, hospitalisation rates for diseases of the eye were lowest in Garfield County amongst all age groups (Coons & Walker, 2008), which is also in contrast to the results presented here. Sub-chapters within the ‘Eye’ ICD chapter include ‘Disorders of the eyelid, lacrimal system and orbit’, ‘Disorders of conjunctiva’, ‘Disorders of lens’, ‘Glaucoma’, ‘Disorders of vitreous body and globe’, and ‘Visual disturbances and blindness’, amongst others. Several studies have raised the issue of eye-related symptoms, such as burning, irritation or itching, associated with UNGD (Rabinowitz et al., 2015;

Steinzor et al., 2013; Subra, 2009, 2010; University of Maryland, 2014). However, these studies have discussed outcomes in terms of self-reported symptoms. In discussing UNGD operations, Brown et al.

(2015) noted that short-term exposure to volatile organic compounds can irritate the eyes, and exposure to diesel emissions can also cause eye irritation. The data presented here would capture the most severe cases rather than residents reporting the symptoms that have typically been discussed in the literature.

Colborn et al. (2011) assessed chemicals used in UNGD operations and found that more than 75%

of the chemicals assessed can affect sensory organs. Likewise, 40% of chemicals can affect the immune system and 46% can have possible health effects on the cardiovascular system and blood (Colborn et al., 2011). Steinzor et al. (2013) conducted air quality testing to analyse chemicals present near the homes of residents who reported symptoms, noting the presence of 17 chemicals that could affect vision/eyes (Steinzor et al., 2013). However, it must be noted that these analyses focused on chemicals used in UNGD operations in the United States, which also includes shale gas.