Personal exposure to NO2 and benzene in the Cape Town region of South Africa is associated with shorter leukocyte telomere length in women

Abstract

Air pollution exposure is a major global health concern and has been associated with molecular aging. Unfortunately, the situation has not received much attention in the African region. The aim of this study was to investigate whether current personal ambient NO₂ and benzene, toluene, ethyl-benzene and xylenes (ortho (o)-, meta (m)- and para (p)-xylene (BTEX) exposure is associated with leukocyte telomere length (LTL), a marker of molecular ageing, in apparently healthy women (mean ± SD age: 42.5 ± 13.4 years) residing in the Cape Town region of South Africa. The repeated measures study collected data from 61 women. Seven-day median (interquartile range (IQR)) personal NO₂ and BTEX exposure levels were determined via compact passive diffusion samplers carried on the person prior to baseline (NO₂: 14.2 (9.4-17.2) μg/m³; Benzene: 3.1 (2.1-5.3) μg/m³) and 6-month follow-up (NO₂: 10.6 (6.6-13.6) μg/m³; Benzene: 2.2 (1.3-4.9) μg/m³) visits. LTL was measured at baseline and follow-up using a real-time PCR method. Multiple linear mixed model analyses (adjusting for age, body mass index, smoking, employment status, level of education and assessment visit) showed that each IQR increment increase in NO₂ (7.0 μg/m³) and benzene (3.3 μg/m³) was associated with -7.30% (95% CI: -10.98 to -3.46%; p < 0.001) and -6.78% (95% CI: -11.88 to -1.39%; p = 0.015) difference in LTL, respectively. The magnitude of these effects of NO₂ and benzene corresponds to the effect of an increase of 10.3- and 6.0-year in chronological age on LTL. Our study shows that personal exposures to NO₂ and benzene are associated with molecular ageing as indicated by LTL in healthy women residing in the Cape Town region.

Keywords: Air pollution; Benzene; Leukocyte telomere length; Nitrogen dioxide; South Africa.