Waste incineration and cancer mortality: a longitudinal controlled population-based study

BACKGROUND: Waste incinerator emissions have been associated with the possibility of increased risk for some cancers. Indeed, emissions are usually composed of heavy metals, dioxins, and furans, including carcinogens. Although emissions levels of incineration activity are considered safe, evidence about the impact of long-term human exposure to low dosages is lacking. We performed a longitudinal population-based study to compare cancer mortality rates between a geographical area exposed to pollutant emissions due to waste incineration and combined local industry activity, a non-exposed control area, and a reference (larger) area. METHODS: Exposed area was defined according to pollutants dispersion models, considering predominant wind intensity and direction. The control area was defined as near-to-the-exposed parishes unaffected by the pollutants emitted at the location where the incinerator is situated. Another larger area (“Large Lisbon”) was also considered as the reference area. Data about cancer mortality was provided by the Portuguese National Statistics Institute. Relative risks (RR) compared standardized (age and sex) specific mortality rates due to malignant neoplasms (ICD-9 and ICD-10) between the exposed area and (a) control are and (b) reference area. RESULTS: In the first five years of the waste incinerator activity (2000-2004), the RR for each cancer-related mortality was not statistically significant (considering either control or reference areas). Considering the average mortality rates between 2015 and 2019 for exposed versus control area, we found increased RR for hepatic and biliary tract (RR = 1.50; 95%CI:1.15-1.85), pancreatic (RR = 1.37; 95%CI:1.06-1.67), and respiratory tract cancer (RR = 1.24; 95%CI:1.07-1.41). No significant RR was found when comparing the exposed with the reference area. CONCLUSIONS: Strengthening public health surveillance systems is pivotal to assess air pollution's impact on health. KEY MESSAGES: • Exposure to emissions from an industrial region including a waste incinerator plant was found to have increased risk for hepatic and biliary tract, pancreatic, and respiratory tract cancer mortality. • Surveillance systems are needed to continuously monitor how long-term exposure to low concentrations of carcinogenic substances from waste incinerator emissions impacts on population’s health.