Residential Exposure to PM2.5 Components and Risk of Childhood Non-Hodgkin Lymphoma in Denmark: A Nationwide Register-Based Case-Control Study

Abstract

In a recent study, we observed an increased risk of childhood non-Hodgkin lymphoma (NHL) associated with exposure to fine atmospheric particulate matter (PM2.5) and black carbon (BC). In this nationwide register-based case-control study, we focus on specific components of PM2.5 in relation to childhood NHL in Denmark (1981–2013) by identifying all incidents of childhood NHL cases in the Danish Cancer Registry (n = 170) and four (cancer-free) randomly selected controls matched by date of birth and sex. We applied PM2.5 concentrations and the following sub-components: secondary organic aerosols (SOA), secondary inorganic aerosols (SIA; i.e., NO3−, NH4+ and SO42−), BC, organic carbon (OC) and sea salt. We calculated a time-weighted exposure average from birth to index-date at all addresses. Odds ratios (ORs) were adjusted for register-based socio-demographic variables. We observed adjusted ORs and 95% confidence intervals (95% CI) of 2.05 (1.10, 3.83) per interquartile range (IQR, 4.83 µg/m3) PM2.5 and 1.73 (0.68, 4.41) per IQR (3.71 µg/m3) SIA, 0.95 (0.71, 1.29) per IQR (0.05 µg/m3) SOA, 1.22 (1.02, 1.46) per IQR (0.39 µg/m3) BC, 1.02 (0.83, 1.26) per IQR (0.56 µg/m3) OC and 1.01 (0.79, 1.30) per IQR (0.87 µg/m3) sea salt, respectively. The estimates were attenuated after adjustment for PM2.5, whereas the OR for PM2.5 remained increased regardless of adjustment for specific components. The findings indicate that the previously observed relation between PM2.5 and childhood NHL may be related to BC (as reported in our previous study) but also partly to SIA, but the role of specific chemical components of PM2.5 remains ambiguous.

Risk of bladder cancer and lymphoma in dogs is associated with pollution indices by county of residence

“…Furthermore, a Spanish case–control study on bladder cancer risk did not find an association between PM 2.5 and UCC 57 . In contrast, NHL has been significantly associated with higher PM 2.5 concentrations, particularly black carbon and volatile organics 58,59 . These subsets of PM 2.5 were not available in the EPA database for our study.…”

“…57 In contrast, NHL has been significantly associated with higher PM 2.5 concentrations, particularly black carbon and volatile organics. 58,59 These subsets of PM 2.5 were not available in the EPA database for our study. In addition, EPA data were relatively sparse for PM 2.5 concentrations, so our negative findings may have been due in part to missing EPA data and inadequate power.…”

Particulate Matter 2.5 and Hematological Disorders From Dust to Diseases: A Systematic Review of Available Evidence

“…Similarly, Taj et al ( 15 ) demonstrated that PM 2.5 components were more positively associated with AML [OR = 1.14; interquartile range (IQR) = 1.00–1.29] than chronic myeloid leukemia and chronic lymphocytic leukemia. The effects of PM 2.5 and other components are related not only to adult leukemia but also to childhood hematological malignancy as reported in studies by Lavigne et al ( 19 ) and Hvidtfeldt et al ( 16 ). Consistently, Lavigne et al ( 19 ) demonstrated the relationship between traffic air pollution exposure in approximately a million pregnant women and the incidence of childhood acute lymphoblastic leukemia (ALL) in their offspring.…”

“…This study design showed the strongest relationship between fetal exposure to air pollution during pregnancy and leukemia in the first year of age. A study by Hvidtfeldt et al ( 16 ) showed a high OR ratio of 2.05 (IQR = 1.10–3.38) in childhood non-Hodgkin lymphoma with exposure to PM 2.5 . Molecular epidemiology studies suggested that DNA methylation of the leukemic gene was positively correlated with exposure to environmental toxins ( 37 , 38 ).…”

“…Protein-forming nanoparticles, termed corona proteins, that cover PM 2.5 particles can alter epigenetics and tumor suppressor gene expression ( 3 , 15 , 41 , 42 ). DNA methylation is highly sensitive to environmental PM 2.5 exposures ( 16 , 20 ). Therefore, this modification can inhibit gene expression, impeding cellular differentiation as one of the steps of leukemic development.…”