Ambient Fine Particulate Matter, Residential Greenness, and Childhood Cancer Risk by Trimester of Exposure in...

Outdoor air pollution is a suspected risk factor for childhood cancer, and there is some evidence that greenness may reduce cancer risk. We examined relationships between prenatal exposure to ambient fine particle air pollution [particulate matter <2.5 µg/m3 (PM2.5)], greenness, and childhood cancer risk in Minnesota.

Cases included individuals born in the state of Minnesota and reported to the Minnesota Cancer Reporting System between 2000 and 2014 (n = 1272, ages 0-14 years at diagnosis) and birth year-matched cancer-free controls (n = 5245). We used Network Common Data Form to estimate monthly PM2.5 exposure and the normalized difference vegetation index for census tract-level greenness. We estimated ORs and 95% confidence intervals (95% CI) between high PM2.5 (≥12 µg/m3) and normalized difference vegetation index (≥0.3) exposure and each childhood cancer per trimester (T1, T2, and T3) and full pregnancy using adjusted logistic regression.

High PM2.5 exposure was associated with increased odds of Burkitt lymphoma [ORT1: 1.93 (1.13-3.30)], lymphoreticular neoplasms [ORT1: 1.43 (1.01-2.01)], Hodgkin lymphoma [ORT2: 2.60 (1.52-4.45)], lymphoid leukemias [ORT3: 1.17 (1.01-1.37)], B-cell leukemia [ORT3: 1.20 (1.02-1.41)], and intracranial and intraspinal embryonal neoplasms [ORT3: 1.90 (1.07-3.37)]. High residential greenness during early life was associated with reduced risk of malignant epithelial neoplasms and melanomas [ORT1: 0.34 (0.13-0.91)]. Unexpectedly, greenness was also associated with increased risk of renal tumors [ORT2: 1.52 (1.11-2.08); full pregnancy OR: 1.30 (0.98-1.72)] and neuroblastoma [ORT3: 1.44 (1.03-2.03)].

We observed elevated risk associated with PM2.5 exposure throughout pregnancy for multiple individual cancers, namely leukemias, lymphomas, and central nervous system tumors.

These findings demonstrate the complex relationship between PM2.5 and greenness.