Children living near coal seam gas extraction sites are more likely to be hospitalised for respiratory diseases than children in other areas, an Australian study has found.

Queensland University researchers compared age-specific hospitalisation rates for almost 81,000 children living in three locations: one where coal seam gas is extracted, a coal mining area (CHI) and a rural area where no mining occurred (RLI) between 1995-2011.

All locations are in Queensland, where the CSG industry has been expanding since 2005.

The strongest associations were found for respiratory diseases in children in the 10-14 years age group, in whom there was a 9% increase in respiratory disease admission rates per year in CSG areas compared to a coal mining areas and a 11% increase per year compared to a rural area with no mining activity. For children under four years of age there was a 7% increase in respiratory disease admission rates per year in the CSG area compared to a coal mining area and a 6% increase compared to a rural area with no mining activity.

The greatest proportion of respiratory disease admissions in the CSG area came from classifications covered by ‘chronic tonsillitis’ and ‘asthma’ in the 10-14 age group. For the 0-4 years age group the most common respiratory disease-related admissions in CSG area were from acute upper respiratory tract infections, acute obstructive laryngitis, pneumonia and asthma.

The study authors said previous studies had highlighted inhalation as the most likely cause of exposure to chemicals potentially associated with unconventional natural gas development (UNGD).

“Air quality can be affected by UNGD as a variety of chemicals are emitted including methane, nitrogen oxides … and volatile organic compounds,” they said.

Ground-level ozone, which can create additional potential health impacts, was formed through nitrogen oxides, they added.

However, while exposure to these pollutants could contribute to respiratory-related outcomes, Queensland Health has stated that the levels detected in the atmosphere at one  CSG site at Tara, would not expected to be associated with adverse health impacts.

The study authors noted there was public unease about expansion of unconventional natural gas development (UNGD), with a growing body of research pointing to a range of potential health impacts that may be caused by air contamination and ground and surface water contamination.

Writing in Maternal and Child Health Journal, Dr Angela Werner (PhD) from the University of Queensland’s Sustainable Minerals Institute said this was the first study in Australia to show increases in hospitalisation rates among children in CSG areas.

While noting limitations of the study, such as the inclusion of repeat admissions and low case numbers and outcomes in some age groups, the results indicated “possible age-specific trends for potential health impacts of CSG within a child and adolescent cohort in Queensland,” they said.

However they emphasised that the research was not intended to examine potential causal associations, and said more sophisticated studies were warranted to explore this.

“These findings show that there are potential maternal and child health policy implications to consider in relation to CSG development activity. Additional work is needed to confirm the associations presented here and in other studies but the current conclusions suggest the need for the consideration of the impacts of UNG activities in relation to the location of communities in which the activities occur”.

“Governments should establish monitoring systems to allow for tracking the incidence and prevalence of disease thought to be associated with UNGD in conjunction with exposure data, particularly for those exposures that occur in utero”.