Background: Geothermal power plants for the production of electricity are currently active in Mt. Amiata, Italy. The present study aimed to investigate the association between chronic low-level exposure to H2S and health outcomes, using a residential cohort study design.
Methods: Spatial variability of exposure to chronic levels of H2S was evaluated using dispersion modelling. Cohorts included people residing in six municipalities of the geothermal district from 01/01/1998 to 31/12/2016. Residence addresses were georeferenced and each subject was matched with H2S exposure metrics and socio-economic status available at census tract level. Mortality and hospital discharge data for neoplasms and diseases of the respiratory, central nervous and cardiovascular systems were taken from administrative health databases. Cox proportional hazard models were used to test the association between H2S exposure and outcomes, with age as the temporal axis and adjusting for gender, socio-economic status and calendar period.
Results: The residential cohort was composed of 33,804 subjects for a total of 391,002 person-years. Analyses reported risk increases associated with high exposure to H2S for respiratory diseases (HR = 1.12 95%CI: 1.00-1.25 for mortality data; HR = 1.02 95%CI: 0.98-1.06 for morbidity data), COPD and disorders of the peripheral nervous system. Neoplasms were negatively associated with increased H2S exposure.
Conclusions: The most consistent findings were reported for respiratory diseases. Associations with increased H2S exposure were coherent in both mortality and hospitalization analyses, for both genders, with evidence of exposure-related trends. No positive associations were found for cancer or cardiovascular diseases.
Keywords: Dispersion models; Geothermal; Hydrogen sulfide; Residential cohort studies; Sustainable energy.
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