Calidad de suelo

Hospital admissions for adults (20-64 year olds) comprised 59.58% of all hospital admissions in the three study areas for 1995-2011. Over the study period, 28.07%, 24.54%, and 6.96% of hospital admissions for adults came from the CSG, CM, and RA study areas, respectively.

‘All-cause’ hospitalisation rates for each age group (20-34, 35-44, and 45-64 years) are shown in Figures 6.6-6.8.

Figure 6.6. Age-specific (20-34 years old), all-cause hospitalisation rates per 1,000 for coal seam gas (CSG), coal mining (CM), and rural/agricultural (RA) areas, 1995-2011.

Figure 6.7. Age-specific (35-44 years old), all-cause hospitalisation rates per 1,000 for coal seam gas (CSG), coal mining (CM), and rural/agricultural (RA) areas, 1995-2011.

Figure 6.8. Age-specific (45-64 years old), all-cause hospitalisation rates per 1,000 for coal seam gas (CSG), coal mining (CM), and rural/agricultural (RA) areas, 1995-2011.

Negative binomial regression was confirmed by the Vuong test and goodness of fit tests. Increases over time in hospitalisation rates in the CSG study area relative to the CM and RA areas (as represented by rate ratios and 95% CI) are shown in Table 6.4 for ‘All-cause’ hospitalisations for each age group, and for each age group and ICD chapter. Only the results that were deemed significant as described in the strategy outlined in Section 2.3 are shown. The results for each age-group of the adult cohort, for each chapter, are provided in full in Appendix K.

Table 6.4. Rate ratios (RR) and 95% confidence interval (CI) for hospitalisations in the three study areas

a Note: CSG = coal seam gas; CM = coal mining; and RA = rural/agricultural. Note: The rate ratios describe any relative increases over time in the hospital admission rates in a given study area compared to the reference area. CSG is compared against the CM reference group (Column 1) and the RA reference group (Column 2). CM is compared against the RA reference group (Column 3). See Table 6.1 for full International Classification of Diseases chapter headings.

b Note: ns = not significant.

c Note: The confidence interval includes 1.00; however, this confidence interval is associated with a p-value of < 0.05.

Analyses confirmed that ‘All-cause’ hospitalisation rates were 2% higher in the CSG area for 20-34 year olds during the study period relative to the CM area, and rates in CM areas were 2% lower than in the RA area. These differences were significant. Hospital admission rates due to any cause increased significantly over time in 35-44 year olds living in the CSG area compared with both the CM and RA areas (2% and 3% higher, respectively). Among 45-64 year olds, ‘All-cause’ hospitalisation rates were 2% higher in the CSG area relative to the RA area, but were not significantly different from the CM area.

Cause-specific hospitalisation rates by age group are summarised below.

3.3.1 20-34 year olds

Rates of hospitalisation due to ‘Neoplasms’ increased significantly over time (10%) for 20-34 year olds in the CSG study area relative only to the CM area, but there was no difference relative to the RA area. Additionally, the CM area had a significant decrease in rates of hospitalisation over time due to

‘Neoplasms’ (6%) compared to the RA area.

The regression models showed a 7% increase in hospitalisation rates for ‘Eye’-related diseases in the CSG area relative only to the CM area, but rates were not significantly different from the RA area. A significant increase of 8% in hospitalisation rates due to ‘Circulatory’ diseases was observed in the CSG area relative only to the RA area, but there was no increase relative to the CM area. In addition, rates increased in the CM area over time compared to the RA area.

Hospitalisation rates for ‘Skin’-related diseases increased significantly over the study period in the CSG area relative only to the CM area (5%); however, these were significantly lower (5%) in the CSG area relative to the RA area. Finally, rates of hospitalisation due to ‘Injuries’ in this age group increased significantly (3%) in the CSG study area relative only to the CM study area, but there was no difference relative to the RA area. The CM area also had a significant decrease in hospitalisation rates compared to the RA study area.

3.3.2 35-44 year olds

There was a 7% increase in hospitalisation rates over time due to ‘Infectious disease’ for 35-44 year olds during the study period in the CSG study area relative only to the RA area, but rates also increased by 7% in the CM study area relative to the RA study area. Likewise, hospital admission rates due to ‘Mental disorders’ increased 5% over the study period in the CSG area relative only to the RA area, but rates also showed a 5% increase in the CM area relative to the RA area.

Significant increases over time were observed in this age group in the CSG study area relative to both the CM and RA areas for hospitalisation rates due to ‘Nervous system’ diseases (4% and 9%, respectively). In addition, rates increased in the CM area over time compared to the RA area. Rates of hospitalisation due to ‘Eye’-related diseases increased 7% over time in the CSG area relative only to the CM area, but were not significantly different from the RA area.

There was a 6% increase in hospitalisation rates due to ‘Circulatory’ disease-related admissions over time in the CSG area compared only to the RA area, but the CM area also showed a 4% increase in

‘Circulatory’ disease-related admission rates over time compared to the RA area. Likewise, the models showed a 6% increase in ‘Respiratory’ disease-related admission rates over time compared only to the RA area, and an 8% increase in ‘Respiratory’ disease-related admission rates over time in the CM area compared to the RA area.

Hospitalisation rates due to ‘Skin’-related diseases increased 10% over time in the CSG area relative only to the CM study area, but there were no differences compared to the RA area. There was also

a decrease in hospital admission rates over time in the CM area compared to the RA area (8%). Finally, significant increases were observed in the CSG study area relative only to the CM area for hospitalisation rates due to ‘Musculoskeletal’ diseases (3%), while the CM area had significant decreases relative to the RA area (4%).

3.3.3 45-64 year olds

Significant increases over time were observed in this age group in the CSG study area relative to both the CM and RA study areas for hospitalisation rates due to ‘Blood/immune’ diseases (13% and 10%, respectively). The most common ‘Blood/immune’ conditions for 45-64 year olds in the CSG area were

‘Anaemia, unspecified’, ‘Iron deficiency anaemia, unspecified’, ‘Thrombocytopenia, unspecified’, and

‘Aplastic anaemia, unspecified’, comprising 25.7%, 18.6%, 12.5%, and 4.3% of all ‘Blood/immune’-related admissions for 45-64 year olds in the CSG area.

There was a 12% increase in hospitalisation rates for 45-64 year olds due to ‘Infectious disease’ in the CSG area relative only to the CM area, but there was no difference relative to the RA area. The CSG study area showed a 9% increase in ‘Endocrine’ disease-related admission rates over time compared only to the RA area, and the CM area showed an 8% increase in ‘Endocrine’ disease-related admission rates over time compared to the RA area. Likewise, the CSG area and the CM area both had significant increases in ‘Mental disorders’-related hospitalisation rates over time compared to the RA area (5% and 7%, respectively).

Admission rates due to ‘Nervous system’-related diseases increased in the CSG study area relative to the RA area (6%) over the study period, but there was no difference relative to the CM study area. In addition, rates increased in the CM area relative to the RA area.

Significant increases were observed in the CSG study area relative to the CM study area for hospitalisation rates due to ‘Skin’-related diseases (9%), but there were no differences relative to the RA study area. There were significant decreases over time in ‘Skin’-related diseases (8%) in the CM

compared to the RA areas. There was a 1% increase in rates of hospitalisation due to ‘Genitourinary’

disease-related admissions in the CSG area compared to the CM area, but there were no differences compared to the RA area. Finally, rates of hospitalisation due to ‘Injuries’ increased in the CSG area over time relative to the CM study area (2%), but there were no differences relative to the RA study area.

In summary, hospitalisation rates increased significantly over time in the CSG area relative to both the CM and RA areas for ‘All-cause’ admissions for 35-44 year olds, and for hospitalisations resulting from ‘Blood/immune’ diseases for 45-64 year olds. These conditions are identified as most relevant according to the strategy outlined in Section 2.3.

According to the strategy outlined in Section 2.3, the next most relevant conditions are those where there were increases in the CSG area relative to the CM area accompanied by decreasing (or

non-significant) trends in the CM area. These included: ‘All-cause’ admissions, ‘Neoplasms’, ‘Injuries’ and

‘Eye’-related diseases for 20-34 year olds; ‘Eye’-related, ‘Skin’-related, and ‘Musculoskeletal’ diseases for 35-44 year olds; and ‘Infectious disease’, ‘Genitourinary’ diseases, ‘Injuries’ and ‘Skin’-related

diseases for 45-64 year olds. Finally, ‘All-cause’ admission rates for 45-64 year olds were greater in the CSG area relative only to the RA area. These are identified as relevant, but to a lesser extent, according to the strategy outlined in Section 2.3.

4 Discussion

The research presented in this chapter was exploratory in nature and sought to assess health outcomes using hospitalisation data across the three study areas using an ERHI assessment framework.

The results presented here are preliminary and are intended to guide further research; hence, the study is not attempting to provide evidence of causality.

In order to identify possible health conditions where increases over time in hospitalisation rates due to CSG may be expected, the studies reviewed in Chapter 2 were referenced. Potential ERHIs identified included respiratory disease, neurological problems, birth defects, cancer, injuries, psychosocial stress, cardiovascular outcomes, vector-borne disease, sexually transmitted infections (STIs), and nephrotoxicity (Adgate et al., 2014; D. Brown, Lewis, & Weinberger, 2015; Navi et al., 2014; Witter et al., 2011).

The potential ERHIs identified in Chapter 2 were matched with the ICD chapters where such outcomes would appear if a person were to be hospitalised for such conditions. Table 6.5 shows the identified ICD chapters for which an increase in hospitalisations over time may be expected due to the environmentally-related health hazard impact potential of UNGD. Also shown in Table 6.5 are the chapters for which an increase in hospitalisation rates over time in the CSG area compared to the CM or RA areas were observed during the study period in order to compare the results found here to the potential ERHIs identified in the literature. Because of the scarcity of previously published data

(generally, but specifically within Australia), it was considered important to examine changes over time in hospitalisations for all ICD chapters, not just those suggested in previous literature.

Table 6.5. Potential health outcomes associated with UNGD and corresponding ICD chapters from the literature alongside the observed outcomes for the CSG study area as discussed in the results of this chapter.^a

Potential outcome^b ICD chapter Observed outcome (age-standardised)^c

Respiratory outcomes Respiratory X

Nephrotoxicity Genitourinary X (‘Genitourinary’

ICD chapter)

X (‘Genitourinary’

ICD chapter) Impaired fertility Genitourinary X (‘Genitourinary’

ICD chapter)

a Note: CSG = coal seam gas; ICD = International Classification of Diseases; and UNGD = unconventional natural gas development.

b Note: Potential health outcomes identified in the literature (Chapter 2).

c Note: Health outcomes identified in this chapter, where the CSG study area presented increases in hospitalisation rates over time relative to the CM and/or RA areas.

A number of additional potential ERHIs were identified in the literature, including fluorosis (Navi et al., 2014) and dermatological symptoms (Adgate et al., 2014); however, these were not included in Table 6.5. They were either specific codes within the chapters, which placed them outside the scope of this work, or would most likely fall within a group for which a person would not be admitted to hospital, as with many of the other symptoms that have been reported (e.g., eye irritation, headaches, nosebleeds).

STIs have been previously identified in the literature; however, they have most likely arisen due to changes in social structures in the communities (briefly discussed in the Introduction) rather than to an ERHI. Additionally, while important to examine in the future, primary diagnoses within the ‘Injuries’

ICD chapter are not typically related to environmentally-related health impacts, so this ICD chapter will not be a focus of the discussion.