The Association Between Urinary Concentrations of Organophosphate Metabolites and Asthma-Related Outcomes Among Schoolchildren From Informal Settlements

Mashudu Mthethwa; Mohamed Jeebhay; Toyib Olaniyan; Lubbe Wiesner; Bhawoodien Parker; Joy Leaner; Martin Röösli; Mohamed Aqiel Dalvie

doi:10.3389/ijph.2023.1606174

The Association Between Urinary Concentrations of Organophosphate Metabolites and Asthma-Related Outcomes Among Schoolchildren From Informal Settlements

Int J Public Health. 2023 Aug 22:68:1606174. doi: 10.3389/ijph.2023.1606174. eCollection 2023.

Authors

Mashudu Mthethwa¹, Mohamed Jeebhay^{1

2}, Toyib Olaniyan¹, Lubbe Wiesner³, Bhawoodien Parker⁴, Joy Leaner⁴, Martin Röösli^{5

6}, Mohamed Aqiel Dalvie¹

Affiliations

¹ Centre for Environmental and Occupational Health Research, School of Public Health, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
² Division of Occupational Medicine, University of Cape Town, Cape Town, South Africa.
³ Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa.
⁴ Department of Environmental Affairs and Developmental Planning, Western Cape Government, Cape Town, South Africa.
⁵ Swiss Tropical Public Health Institute, Allschwil, Switzerland.
⁶ University of Basel, Basel, Switzerland.

Abstract

Objectives: There is inconsistent evidence on the relationship between pesticide exposure and childhood respiratory outcomes in non-agricultural settings. This study investigated the association between organophosphate (OP) pesticide exposure and asthma-related outcomes in children residing in four informal settlements. Methods: The study was a longitudinal study of 590 schoolchildren, with a 12 months follow-up period. A standardised questionnaire adopted from the International Study of Asthma and Allergies in Childhood was administered to caregivers for child's respiratory symptoms and household characteristics. Spirometry and fractional-exhaled nitric oxide, including a phadiatop test (atopy status) and urinary dialkyl phosphate (DAP) metabolites were measured at baseline and follow-up. DAP metabolites included diethylphosphate (DEP) and dimethyl phosphate (DMP) measured at baseline and follow-up and dimethylthiophosphate (DMTP) measured only at baseline. Results: The mean ages of schoolchildren were 9.9 ± 0.91 years and the overal incidence proportions of new doctor diagnosed asthma was 2.2%. No consistent patterns of increased risk of asthma outcomes with increasing DAP concentrations was found in multivariate analysis. Conclusion: Future studies with longer follow-up periods and repeated OP biomonitoring are recommended.

Keywords: child asthma; informal settlements; organophosphates; pesticides; urinary dialkyl phosphates.

MeSH terms

Asthma* / epidemiology
Child
Humans
Hypersensitivity*
Longitudinal Studies
Organophosphates / adverse effects
Pesticides* / adverse effects

Substances

Pesticides
Organophosphates

Grants and funding

The following organisations are acknowledged for funding this research: Western Cape Department of Environmental Affairs and Development Planning (DEA&DP), South Africa (Study Tender: Conduct Comprehensive Human Health Risk Assessment (HRA) Studies within identified areas across the Western Cape, Ref: EADP7/ 2013); the South African National Research Foundation (SANRF) and the Medical Research Council (MRC).