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Spatiotemporal variability of urinary pesticide biomarker levels in 201 South African children sampled five times over two years

Molomo, Regina Ntsubise ; Veludo, Adriana Fernandes ; Viglietti, Paola ; Wey, Hannah ; Petitpierre, Anouk ; Lindh, Christian LU orcid ; Röösli, Martin ; Dalvie, Mohamed Aqiel and Fuhrimann, Samuel (2025) In Environment International 202.
Abstract

Background: Understanding pesticide exposure variability over time among children is crucial towards understanding potential acute and long-term health effects of pesticides but data is lacking. Objective: We assessed spatiotemporal and seasonal variability of urinary biomarkers in children at five time points across two years within three agriculturally intensive areas of the Western Cape, South Africa (Grabouw, Piketberg and the Hex River Valley). Methods: A total of 201 children (aged 9–15 years) provided a total of 1005 spot urine samples and completed pesticide exposure-related questionnaires at five time points between 2017 and 2019. Nineteen urinary pesticide biomarkers including organophosphates, pyrethroids, dithiocarbamate and... (More)

Background: Understanding pesticide exposure variability over time among children is crucial towards understanding potential acute and long-term health effects of pesticides but data is lacking. Objective: We assessed spatiotemporal and seasonal variability of urinary biomarkers in children at five time points across two years within three agriculturally intensive areas of the Western Cape, South Africa (Grabouw, Piketberg and the Hex River Valley). Methods: A total of 201 children (aged 9–15 years) provided a total of 1005 spot urine samples and completed pesticide exposure-related questionnaires at five time points between 2017 and 2019. Nineteen urinary pesticide biomarkers including organophosphates, pyrethroids, dithiocarbamate and triazoles were analyzed using liquid chromatography tandem mass spectrometry and adjusted for specific gravity. Intraclass correlation coefficients (ICCs) evaluated temporal agreements between repeated urine samples. Linear mixed-effects models assessed the effects of farm residency, study area and pesticide spraying period on urinary pesticides levels. Risks of daily intake of pesticides were estimated using reverse dosimetry. Results: Ten out of fourteen detected biomarkers had a detection frequency above 75%. Levels of 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPy) (ICC = 0.60) and 3, 5, 6-trichloropyridinol (TCPy; ICC = 0.49) showed moderate and fair temporal agreement between the five sampling points. Children in Grabouw had on average higher biomarker levels compared to the other two areas. Pesticides’ specific spraying periods were associated with an increased TCPy (+32%), IMPy (+79%) and ethylene thiourea (ETU) (+81%) levels compared to non-spraying periods. The estimated daily intakes (EDIs) for most biomarkers were within the acceptable daily intakes (ADIs). However, EDIs exceeded the ADIs in 23.0% of children for TCPy, 8.9% for IMPy, and 0.5% for both 3,5-dichlorophenyl-2-chloroacetic acid (DCCA) and 4-hydroxy-pyrimethanil (OHP). Discussion: High temporal variability and regional exposure contrasts highlight the need for repeated urinary biomarker measurements across locations to accurately assess pesticide exposure for epidemiological studies in rural children. Observed exposure levels exceeding safety thresholds for organophosphates, pyrethroids and triazoles warrant further investigation.

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author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Children, Estimated daily intake, Organophosphates, Pyrethroids, Seasonality, Spatiotemporal, Urinary pesticide biomarkers
in
Environment International
volume
202
article number
109651
publisher
Elsevier
external identifiers
  • pmid:40628181
  • scopus:105009803892
ISSN
0160-4120
DOI
10.1016/j.envint.2025.109651
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 The Authors
id
77cbb078-6a52-42c0-92a2-4257e3036b0e
date added to LUP
2025-11-26 14:54:10
date last changed
2025-11-27 02:15:41
@article{77cbb078-6a52-42c0-92a2-4257e3036b0e,
  abstract     = {{<p>Background: Understanding pesticide exposure variability over time among children is crucial towards understanding potential acute and long-term health effects of pesticides but data is lacking. Objective: We assessed spatiotemporal and seasonal variability of urinary biomarkers in children at five time points across two years within three agriculturally intensive areas of the Western Cape, South Africa (Grabouw, Piketberg and the Hex River Valley). Methods: A total of 201 children (aged 9–15 years) provided a total of 1005 spot urine samples and completed pesticide exposure-related questionnaires at five time points between 2017 and 2019. Nineteen urinary pesticide biomarkers including organophosphates, pyrethroids, dithiocarbamate and triazoles were analyzed using liquid chromatography tandem mass spectrometry and adjusted for specific gravity. Intraclass correlation coefficients (ICCs) evaluated temporal agreements between repeated urine samples. Linear mixed-effects models assessed the effects of farm residency, study area and pesticide spraying period on urinary pesticides levels. Risks of daily intake of pesticides were estimated using reverse dosimetry. Results: Ten out of fourteen detected biomarkers had a detection frequency above 75%. Levels of 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPy) (ICC = 0.60) and 3, 5, 6-trichloropyridinol (TCPy; ICC = 0.49) showed moderate and fair temporal agreement between the five sampling points. Children in Grabouw had on average higher biomarker levels compared to the other two areas. Pesticides’ specific spraying periods were associated with an increased TCPy (+32%), IMPy (+79%) and ethylene thiourea (ETU) (+81%) levels compared to non-spraying periods. The estimated daily intakes (EDIs) for most biomarkers were within the acceptable daily intakes (ADIs). However, EDIs exceeded the ADIs in 23.0% of children for TCPy, 8.9% for IMPy, and 0.5% for both 3,5-dichlorophenyl-2-chloroacetic acid (DCCA) and 4-hydroxy-pyrimethanil (OHP). Discussion: High temporal variability and regional exposure contrasts highlight the need for repeated urinary biomarker measurements across locations to accurately assess pesticide exposure for epidemiological studies in rural children. Observed exposure levels exceeding safety thresholds for organophosphates, pyrethroids and triazoles warrant further investigation.</p>}},
  author       = {{Molomo, Regina Ntsubise and Veludo, Adriana Fernandes and Viglietti, Paola and Wey, Hannah and Petitpierre, Anouk and Lindh, Christian and Röösli, Martin and Dalvie, Mohamed Aqiel and Fuhrimann, Samuel}},
  issn         = {{0160-4120}},
  keywords     = {{Children; Estimated daily intake; Organophosphates; Pyrethroids; Seasonality; Spatiotemporal; Urinary pesticide biomarkers}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Environment International}},
  title        = {{Spatiotemporal variability of urinary pesticide biomarker levels in 201 South African children sampled five times over two years}},
  url          = {{http://dx.doi.org/10.1016/j.envint.2025.109651}},
  doi          = {{10.1016/j.envint.2025.109651}},
  volume       = {{202}},
  year         = {{2025}},
}