Browsing by Author "Mthethwa, Mashudu"

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    The relationship between urinary organophosphate pesticide metabolites and asthma-related outcomes at 12-month follow-up in school children residing in informal settlements in the Western Cape
    (2021) Mthethwa, Mashudu; Dalvie, Aqiel; Jeebhay, Mohamed; Olaniyan, Toyib
    Background: Evidence on the relationship between pesticide exposure and respiratory outcomes is mostly from farm workers. In most settings, poor /rich there is limited information on non-agricultural settings, particularly in children. Objective: This study investigated the relationship between urinary concentrations of the organophosphate pesticide (OP) metabolites and asthma-related outcomes among schoolchildren in four informal settlements in the Western Cape in South Africa. Methods: This study was a longitudinal study of 590 schoolchildren, with a 12-month follow up period. A standardised questionnaire adopted from the International Study of Asthma and Allergies in Childhood (ISAAC) was administered to caregivers for child's respiratory symptoms and household characteristics. Spirometry and fractional-exhaled nitric oxide (FeNO), including a phadiatop test (atopy status) and urinary dialkyl phosphate (DAP) metabolites diethylphosphate (DEP), dimethylthiophosphate (DMTP)] were measured at baseline and follow-up. Dimethylphosphate (DMP) was measured only at baseline. Results: Mean ages of schoolchildren were (9.9 ± 0.91 years) and median DAP was 32.9 ng/ml (18.4 – 52.9 ng/ml) at baseline. Incidence proportions of new asthma outcome cases at 12- months were 2.2 % doctor diagnosed asthma, 17.8 % asthma-symptom score ≥ 2, 14.5 % forced expiratory volume 1< lower limit of normal, and 5.9 % airway inflammation across all areas. In the linear mixed and fixed effect model, no consistent patterns of increased risk of new asthma-associated outcomes at the 12-month was found. However, there was a significant increase in airway inflammation (β:2.99 (95% CI: 0.48 - 5.50) in the 3rd DEP quintile (1.9 – 3.0 ng/mL) compared to the reference quintile (1.10 ng/ml). Conclusion: DAP concentrations among school children were found to be higher than those of children in other settings. However, the study did not find consistent associations between urinary concentrations of DAP metabolites and asthma related outcomes over a 12-month follow-up period among schoolchildren. Future studies with a longer follow-up period and repeated OP pesticide biomonitoring are recommended.