GAS flaring and cancer in the Amazon of Ecuador: an ecological study

Background Gas flaring associated with oil extraction is a major source of environmental pollution and has been linked to adverse health outcomes worldwide. In the Ecuadorian Amazon, decades of oil exploitation have resulted in widespread gas flaring, disproportionately affecting Indigenous and rural communities.Objective This study assessed the association between exposure to gas flaring and cancer incidence in the provinces of Sucumbíos and Orellana, Ecuador, between 2010 and 2019.Methods We conducted an ecological study at the parish level using data from the Quito Cancer Registry, which records diagnosed cancer cases among residents of Sucumbíos and Orellana. Exposure was defined according to the presence and number of active gas flaring sites identified through participatory mapping and spatial analysis. Age-standardised cancer incidence rates were calculated by sex and period (2010–2014; 2015–2019). Relative risks (RR) with 95% confidence intervals were estimated by comparing exposed and unexposed parishes.Results A total of 1484 cancer cases were identified. Cancer incidence was higher in parishes exposed to gas flaring than in non-exposed parishes for both men and women in both periods. Relative risks ranged from 2.11 to 3.98 among men and from 1.53 to 3.28 among women, all statistically significant. Among women, a clear exposure–response gradient was observed, with higher cancer incidence in parishes, with more flaring sites.Conclusions Parish-level exposure to gas flaring was strongly associated with higher cancer incidence in the Ecuadorian Amazon. These findings highlight the need for environmental mitigation, strengthened cancer surveillance, and targeted public health interventions in oil-affected regions.