Comunidades Hidrobiológicas

There were 37,751 admissions to hospital for 1995-2011 in the CSG area for children and adolescents (0-19 years old). For this cohort, the minimum number of admissions in one month was 12, while the maximum number of admissions in one month was 122. There were 8,879 admissions in the period of ‘very low’ GWD activity (January 1995 - March 1999); 9,737 admissions during the activity period defined as ‘low’ (April 1999 - June 2003); 9,566 admissions during the ‘medium’ GWD activity period (July 2003 - September 2007); and 9,569 admissions during the period of ‘intense’ activity (October 2007 - December 2011).

The Vuong test and goodness of fit tests confirmed negative binomial regression as the preferred model. The health conditions (via ICD chapters) where there were statistically significant increases over time in age-specific hospitalisation rates in the CSG area relative to both the CM and the RA areas were reported in Chapter 6. Rate ratios and 95% CI for age-specific hospital admission rates in periods of

‘low’, ‘medium’, and ‘intense’ GWD activity, relative to the period of ‘very low’ GWD activity, were

calculated for each of these conditions and are shown in Table 7.2. Only significant associations are shown in the table. Results for each age group of the child/adolescent cohort, for each chapter, are provided in full in Appendix L.

Table 7.2. Rate ratios (RR) and 95% confidence interval (CI) for age-specific hospitalisation rates (child/adolescent cohort) as a function of gas well development activity.^ab

Low vs very low Medium vs very low Intense vs very low

aNote: The reference category is ‘very low’ (January 1995 - March 1999) and all gas well development activity periods are shown in Figure 7.1.

b Note: ns = not significant.

As in Chapter 6, the only age group in the child/adolescent cohort where increases were observed for ‘All-cause’ hospitalisation rates was for 5-9 year olds. Hospitalisation rates for 5-9 year olds increased by 3% over time in the CSG area relative only to the RA area. Table 7.2 shows that ‘All-cause’

hospitalisation rates were higher for each period of GWD activity relative to the ‘very low’ period, but the increase was not consistent over time. Hospitalisation rates were 12% higher in the period of ‘low’ GWD activity compared with the period of ‘very low’ activity and 24% higher in the period of ‘medium’ GWD activity. Hospitalisation rates were 15% higher in the period of ‘intense’ GWD activity compared with the period of ‘very low’ activity.

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

3.2.1 0-4 year olds

In Chapter 6, it was shown that rates of hospitalisation due to ‘Endocrine’ diseases were

significantly higher (8%) in this age group in the CSG area relative only to the CM area. As in Table 7.2 above, hospitalisation rates due to ‘Endocrine’ diseases were 93% higher in the period of ‘medium’ GWD activity compared with the period of ‘very low’ activity. Rates were not significantly different in periods of ‘low’ or ‘intense’ GWD activity compared with ‘very low’ activity.

While hospitalisation rates for ‘Respiratory’ diseases were higher in the CSG area than in the RA area (but not CM) as discussed in Chapter 6, hospitalisation rates did not increase as a function of GWD

activity within the CSG area (because no associations were observed, the data are not included in the table, but the results can be found in Appendix L).

3.2.2 5-9 year olds

In Chapter 6, it was shown that higher hospitalisation rates were observed over time in the CSG area relative to both CM and RA areas for ‘Blood/immune’ diseases and ‘Ear’ diseases. As in Table 7.2, rates of hospitalisation due to ‘Blood/immune’ diseases were over 13 times higher in the period of ‘low’

GWD activity compared with the period of ‘very low’ activity and more than 48 times higher in the period of ‘medium’ activity compared with the period of ‘very low’ activity. No differences in rates were observed between periods of ‘very low’ and ‘intense’ GWD activity. A total of 67 ‘Blood/immune’

disease-related admissions were observed for this age group over the entire study period.

Hospitalisation rates related to ‘Digestive’ diseases were found to increase in the CSG area relative only to the CM area (discussed in Chapter 6). Upon examining GWD activity, it was found that

hospitalisation rates for ‘Digestive’ diseases in this age group were 50% and 64% higher in the periods of

‘medium’ and ‘intense’ activity, respectively, compared with the period of ‘very low’ activity. Rates were not significantly different in the period of ‘low’ GWD activity compared with the period of ‘very low’

GWD activity. There were 907 ‘Digestive’ disease-related hospital admissions for 5-9 year olds over the study period.

While hospitalisation rates for ‘Eye’ and ‘Respiratory’ diseases were higher in the CSG area compared only to the RA area (but not CM), hospitalisation rates did not increase as a function of GWD activity within the CSG area (because no associations were observed, the data are not included in Table 7.2).

3.2.3 10-14 year olds

In Chapter 6, it was shown that hospitalisation rates for ‘Ear’ diseases were significantly higher in this age group for the CSG area relative to both the CM and RA areas. While hospitalisations due to ‘Ear’

diseases were 80% higher in the period of ‘intense’ GWD activity than in the period of ‘very low’

activity, there was no difference in hospitalisation rates for ‘low’ or ‘medium’ periods of GWD activity versus ‘very low’ GWD activity.

While hospitalisation rates for ‘Respiratory’ diseases were higher in the CSG area relative only to the RA area (but not CM), and hospitalisation rates for ‘Skin’ diseases were higher in the CSG area relative only to the CM area (discussed in Chapter 6), hospitalisation rates for both of these ICD chapters did not increase as a function of GWD activity within the CSG area (because no associations were observed, the data are not included in Table 7.2).

3.2.4 15-19 year olds

As per Chapter 6, increases in hospitalisation rates for 15-19 year olds were not observed for any of the ICD chapters in the CSG area compared with both the CM and RA areas. However, for this age group, the CSG area had higher rates of hospitalisation for ‘Neoplasms’ and ‘Skin’ diseases relative only

to the CM area (but not RA). Hospitalisation rates due to ‘Neoplasms’ were 121% higher in the ‘medium’

GWD activity period compared with the ‘very low’ GWD activity period; however, hospitalisation rates were not higher for the ‘low’ or ‘intense’ GWD activity periods relative to the ‘very low’ period.

Hospitalisation rates due to ‘Skin’ diseases were 51% higher in the period of ‘intense’ GWD activity compared with the period of ‘very low’ activity. Rates were not significantly different in periods of ‘low’

or ‘medium’ GWD activity compared with the period of ‘very low’ activity.

In summary, hospitalisation rates increased across all GWD periods only for ‘All-cause’

admissions for 5-9 year olds; however, there was no consistent positive dose-response relationship. A number of cause-specific increases in hospitalisation rates were observed in the ‘medium’ GWD activity period compared to the ‘very low’ period (i.e., ‘Neoplasms’ for 15-19 year olds and ‘Endocrine’ diseases for 0-4 year olds), while increases in rates for other causes occurred only in the ‘intense’ GWD activity period compared to the ‘very low’ period (i.e., ‘Ear’ diseases for 10-14 year olds and ‘Skin’ diseases for 15-19 year olds).

While hospitalisation rates for ‘Digestive’ diseases for 5-9 year olds increased in the ‘medium’ and

‘intense’ GWD activity periods compared to the ‘very low’ period, the rates in the ‘low’ period were not significantly higher than in the ‘very low’ period. Finally, hospital admissions for ‘Blood/immune’

diseases for 5-9 year olds increased over time in conjunction with both the ‘low’ and ‘medium’ periods compared to the ‘very low’ period; however, the ‘intense’ period did not have significantly higher rates relative to the ‘very low’ period.