Multiple Air Pollutants Exposure and Leukemia Incidence in Tehran, Iran

Abstract

Background and Aim: Leukemia is one of the most common cancers and may be associated with exposure to environmental carcinogens, especially outdoor air pollutants. The objective of this study was to investigate the association of ambient air pollution and leukemia in Tehran, Iran. Methods: In this ecological study, data about the residential district of leukemia cases diagnosed from 2010 to 2016 were inquired from the Ministry of Health cancer database. Data from a previous study was used to determine long-term average exposure to different air pollutants in 22 districts of Tehran. Latent profile analysis (LPA) was used to classify pollutants in two exposure profiles. The association between air pollutants and leukemia incidence was analyzed by negative binomial regression. Results: The districts with higher concentrations for all pollutants were near the city center. The incidence rate ratio (IRR) was positive but non-significant for most of the air pollutants. However, annual mean NOx was directly and significantly associated with total leukemia incidence in the fully adjusted model (IRR (95% CI): 1.03 (1.003, 1.06) per 10 ppb increase). Based on LPA, districts with a higher multiple air-pollutants profile were also associated with higher leukemia incidence (IRR (95% CI): 1.003 (0.99, 1.007) per 1 ppb increase). Conclusions: Our study shows that districts with higher air pollution (nitrogen oxides and multi-pollutants) have higher incidence rates of leukemia in Tehran, Iran. This study warrants conducting further research with individual human data and better control of confounding. Keywords Air pollution ; multiple pollutants; pollutant profile; Leukemia; Latent profile analysis