Exposure to Outdoor Particulate Matter Air Pollution and Risk of Gastrointestinal Cancers in Adults: A Systematic Review and Meta-Analysis of Epidemiologic Evidence.

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From: Environmental Health Perspectives(Vol. 130, Issue 3)
Publisher: National Institute of Environmental Health Sciences
Document Type: Report
Length: 9,059 words
Lexile Measure: 1740L

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Abstract :

BACKGROUND: Outdoor air pollution is a known lung carcinogen, but research investigating the association between particulate matter (PM) and gastrointestinal (GI) cancers is limited. OBJECTIVES: We sought to review the epidemiologic literature on outdoor PM and GI cancers and to put the body of studies into context regarding potential for bias and overall strength of evidence. METHODS: We conducted a systematic review and meta-analysis of epidemiologic studies that evaluated the association of fine PM [PM with an aerodynamic diameter of [less than or equal to]2.5 [micro]m (P[M.sub.2.5])] and P[M.sub.10] (aerodynamic diameter RESULTS: Twenty studies met inclusion criteria and included participants from 14 countries; nearly all were of cohort design. All studies identified positive associations between PM exposure and risk of at least one GI cancer, although in 3 studies these relationships were not statistically significant. Three of 5 studies estimated associations with P[M.sub.10] and satisfied inclusion criteria for meta-analysis, but each assessed a different GI cancer and were therefore excluded. In the random-effects meta-analysis of 13 studies, P[M.sub.2.5] exposure was associated with an increased risk of GI cancer overall [risk ratio (RR) = 1.12; 95% CI: 1.01, 1.24]. The most robust associations were observed for liver cancer (RR = 1.31; 95% CI: 1.07, 1.56) and colorectal cancer (RR = 1.35; 95% CI: 1.08, 1.62), for which all studies identified an increased risk. We rated most studies with "probably low" risk of bias and the overall body of evidence as "moderate" quality with "limited" evidence for this association. We based this determination on the generally positive, but inconsistently statistically significant, effect estimates reported across a small number of studies. CONCLUSION: We concluded there is some evidence of associations between P[M.sub.2.5] and GI cancers, with the strongest evidence for liver and colorectal cancers. Although there is biologic plausibility for these relationships, studies of any one cancer site were few and there remain only a small number overall. Studies in geographic areas with high GI cancer burden, evaluation of the impact of different PM exposure assessment approaches on observed associations, and investigation of cancer subtypes and specific chemical components of PM are important areas of interest for future research. https://doi.org/10.1289/EHP9620

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Gale Document Number: GALE|A696826093