Exposure to wildfire-related PM2.5 and site-specific cancer mortality in Brazil from 2010 to 2016: A retrospective study

Abstract

Background Long-term exposure to fine particles ≤2.5 μm in diameter (PM2.5) has been linked to cancer mortality. However, the effect of wildfire-related PM2.5 exposure on cancer mortality risk is unknown. This study evaluates the association between wildfire-related PM2.5 and site-specific cancer mortality in Brazil, from 2010 to 2016. Methods and findings Nationwide cancer death records were collected during 2010–2016 from the Brazilian Mortality Information System. Death records were linked with municipal-level wildfire- and non-wildfire-related PM2.5 concentrations, at a resolution of 2.0° latitude by 2.5° longitude. We applied a variant difference-in-differences approach with quasi-Poisson regression, adjusting for seasonal temperature and gross domestic product (GDP) per capita. Relative risks (RRs) and 95% confidence intervals (CIs) for the exposure for specific cancer sites were estimated. Attributable fractions and cancer deaths were also calculated. In total, 1,332,526 adult cancer deaths (age ≥ 20 years), from 5,565 Brazilian municipalities, covering 136 million adults were included. The mean annual wildfire-related PM2.5 concentration was 2.38 μg/m3, and the annual non-wildfire-related PM2.5 concentration was 8.20 μg/m3. The RR for mortality from all cancers was 1.02 (95% CI 1.01–1.03, p < 0.001) per 1-μg/m3 increase of wildfire-related PM2.5 concentration, which was higher than the RR per 1-μg/m3 increase of non-wildfire-related PM2.5 (1.01 [95% CI 1.00–1.01], p = 0.007, with p for difference = 0.003). Wildfire-related PM2.5 was associated with mortality from cancers of the nasopharynx (1.10 [95% CI 1.04–1.16], p = 0.002), esophagus (1.05 [95% CI 1.01–1.08], p = 0.012), stomach (1.03 [95% CI 1.01–1.06], p = 0.017), colon/rectum (1.08 [95% CI 1.05–1.11], p < 0.001), larynx (1.06 [95% CI 1.02–1.11], p = 0.003), skin (1.06 [95% CI 1.00–1.12], p = 0.003), breast (1.04 [95% CI 1.01–1.06], p = 0.007), prostate (1.03 [95% CI 1.01–1.06], p = 0.019), and testis (1.10 [95% CI 1.03–1.17], p = 0.002). For all cancers combined, the attributable deaths were 37 per 100,000 population and ranged from 18/100,000 in the Northeast Region of Brazil to 71/100,000 in the Central-West Region. Study limitations included a potential lack of assessment of the joint effects of gaseous pollutants, an inability to capture the migration of residents, and an inability to adjust for some potential confounders. Conclusions Exposure to wildfire-related PM2.5 can increase the risks of cancer mortality for many cancer sites, and the effect for wildfire-related PM2.5 was higher than for PM2.5 from non-wildfire sources.

Long‐term exposure to air pollution and incidence of gastric and the upper aerodigestive tract cancers in a pooled European cohort: The ELAPSE project

“…33 Long-term exposure to PM 2.5 from wildfires in Brazil showed increased mortality from cancers of the nasopharynx, esophagus and stomach. 7 In this large European study focusing on low level air pollution levels even below current EU standards, the long-term exposure to air pollution increased the incidence of UADT, but no association was found for gastric cancer. Note however, that remains above the recently up-dated WHO air quality guidelines (eg, 10 μg/m 3 for NO 2 and 5 μg/m 3 PM 2.5 ).…”

“…5,6 Further indication for an association of PM 2.5 with gastric and UADT cancer comes from wildfire exposure in Brazil. 7 Pritchett et al 8 summarized the results for an association between outdoor particulate matter (PM) air pollution and the risk of gastrointestinal cancers.…”

“…Indirect indication for an association of airborne pollutants with gastric and UADT cancer comes from occupational and industrial settings 5,6 . Further indication for an association of PM 2.5 with gastric and UADT cancer comes from wildfire exposure in Brazil 7 . Pritchett et al 8 summarized the results for an association between outdoor particulate matter (PM) air pollution and the risk of gastrointestinal cancers.…”

Health effects of wildfires

“…91 Emerging literature also links wildfire smoke exposure with skin diseases, 92 eye conditions 93 and cancer. 94,95 For example, Fadadu et al 92 document increased rates of clinic visits for atopic dermatitis or itch in San Francisco during the California Camp Fire in November 2018.…”

Association of Wildfire Exposure While Recovering From Lung Cancer Surgery With Overall Survival

“…Exposure to air pollution is associated with worse lung cancer survival . Wildfire smoke is a major contributor to particulate air pollution; exposure to wildfire smoke has consistently been associated with respiratory morbidity, including lung cancer risk; and exposure to wildfire particulate matter smaller than 2.5 μm has been associated with cancer mortality . However, proximity to wildfire leads not only to increased exposure to air pollution from the smoke plume but also to health hazards from water and soil contamination, increased stress and other detrimental mental health consequences deriving from the threat to personal safety, displacement, and disruptions in access to care .…”