Routine exposure to agricultural pesticides may be affecting the brains of children living in South Africa’s farming regions, and affecting their cognitive abilities.
This is according to findings from scientists at the Centre for Environmental and Occupational Health Research in the School of Public Health at the University of Cape Town (UCT) and the Swiss Tropical and Public Health Institute at the University of Basel.
The collaborative study forms part of the South African–Swiss Bilateral SARChI Chair in Global Environmental Health led by Professors Aqiel Dalvie and Martin Röösli, and was published in Environmental Research, reports Mail & Guardian.
Drawing on data collected between 2017 and 2019, the teams assessed 445 schoolchildren, aged nine to 16, from seven schools across three intensively farmed regions of the Western Cape: the Hex River Valley (table grapes), Grabouw (pome fruits) and Piketberg (fruit orchards and wheat).
The findings are part of the ongoing Child Health Agricultural Pesticide Study in South Africa (CapSA), of which Dalvie is the principal investigator, and examines how long-term pesticide exposure affects children’s health, particularly neurobehavioral and reproductive outcomes.
According to UCT PhD candidate Paola Viglietti – the first author of the study, which forms part of her doctoral research – 12 of the 13 pesticides they tested for were detected in the children, with several chemicals, including chlorpyrifos, pyrethroids, hydroxy-tebuconazole, mancozeb and 2,4-D, found in more than 98% of the participants.
“Higher average levels of chlorpyrifos and profenfos were associated with poorer cognitive flexibility, while higher average levels of chlorpyrifos, profenfos, pyrethroids and 4-hydroxy-pyrimethanil were associated with poorer inhibitory control,” she said.
The study noted that these findings align with a growing global body of evidence showing that chronic, low-dose pesticide exposure during childhood and adolescence – a time marked by “intense brain maturation, synaptic pruning and neural reorganisation” – may disrupt healthy neurocognitive development.
Executive functioning (EF), in particular, appears highly vulnerable. EF encompasses the cognitive skills that enable children to plan, focus, solve problems and regulate their behaviour.
Viglietti emphasised this vulnerability. She said the results suggest that postnatal exposure to organophosphates, pyrethroids and triazole fungicides may impair “specific domains in EF in children”.
She said children are naturally more susceptible to environmental toxins because their organs are still developing and “their higher dermal contact, including hand-to-mouth activities, larger food intake per unit height and body weight, breathing in relatively larger volumes of air, and playing in more hazardous zones” all increase exposure.
“Pesticide exposure among children living in agricultural communities continues long after birth via household dust, pesticide drift and contaminated food and water,” Viglietti said.
“This chronic, low-level exposure during childhood and adolescence, periods marked by intense brain maturation, synaptic pruning and neural reorganisation, may lead to cumulative neurotoxic effects that compromise neurocognitive development.”
The study describes EF as a set of higher-order mental processes – including inhibitory control, working memory and cognitive flexibility – that are predominantly governed by the prefrontal cortex, which undergoes significant development from childhood into early adulthood.
“These functions are essential for academic achievement, emotional regulation and long-term well-being. Disruptions caused by environmental agents such as pesticides may hinder children from reaching their full developmental potential,” the researchers write.
“As pesticide exposures during childhood and into adolescence coincide with critical developmental windows,” Viglietti added, neurotoxic effects may be especially pronounced.
Early childhood through adolescence is a sensitive period marked by rapid cognitive development and neural plasticity, she said. “Chronic exposure during these vulnerable stages may translate into enduring impairments in attention, problem-solving flexibility and self-regulation, skills crucial for success across academic, social and occupational domains.”
The authors noted that disruptions to EF because of environmental agents like pesticides are particularly concerning, as they may hinder children from reaching their full developmental potential.
In South Africa, these risks are worsened by the realities of agricultural life. “In local agricultural communities, children’s pesticide exposures are often exacerbated by factors such as proximity to treated fields and weak enforcement of protective measures,” Viglietti noted.
The authors said in their study that pesticide exposure represents a significant, yet modifiable, environmental risk factor for child neurocognitive development.
Globally, millions of children are routinely exposed to pesticides through contaminated food, water, air, and soil, particularly in agricultural regions.
In low and middle-income countries, including South Africa, these exposures are often compounded by weak regulatory oversight, limited protective infrastructure and socioeconomic vulnerabilities.
“A growing body of evidence indicates that even low-dose, chronic exposure to neurotoxic pesticides post-natally (across childhood and into adolescence) may disrupt healthy brain development, with ramifications for cognitive, behavioural, and emotional functioning.”
South Africa has the highest pesticide application rates in Sub-Saharan Africa, with more than 3 000 registered formulations, including many known to be neurotoxic or endocrine-disrupting.
A 2017 study in the Western Cape found that farms growing stone fruit, grapes and wheat used up to 96 active ingredients, including 47 fungicides, 31 insecticides and 18 herbicides.
The authors argue that the new findings strengthen the case for stricter controls over pesticide registration, sale, storage and handling, and for interventions aimed at reducing children’s exposure.
“Given that these participants are not in occupation, a recommendation is to implement targeted interventions in agricultural populations, such as an educational programme on pesticide-related activities in schools, and to learn from current interventions and their effectiveness,” she added.
The findings also underscore the need for regulatory and public health responses that prioritise exposure reduction, especially in high-risk and underrepresented settings such as rural South Africa.
The authors added that their findings advance the broader literature by providing data from a rural African context, highlighting that rural regions in Africa remain severely under-represented in global pesticide-neurotoxicity studies despite high exposure burdens.
Study details
Postnatal pesticide exposure and executive function in children and adolescents: Findings from South Africa
Paola Gabriela Viglietti, Lena Jäggi, Hannah Wey, Anouk Petitpierre, Christian Lindh, Kim-Louise Rousseau, Jade Mac Donnell, Martin Röösli, Susan Malcolm Smith, Samuel Fuhrimann, Mohamed Aqiel Dalvie.
Published in Environmental Research on 15 January 2026
Abstract
Introduction
Postnatal pesticide exposure and its impact on executive functioning (EF) in children and adolescents remains under-explored, particularly in African agricultural contexts. This study investigated associations between urinary pesticide biomarkers and EF in the Child health Agricultural Pesticide study in South Africa (CapSA).
Methods
Data from 445 participants (mean age: 10.6 years; 55.3 % male) were analysed. EF was assessed using three Cambridge Neuropsychological Test Automated Battery (CANTAB) subtests: the Multitasking Test (MTT, cognitive flexibility), Rapid Visual Information Processing (RVP, inhibitory control), and Spatial Working Memory (SWM, visuospatial working memory). Average levels of 13 pesticide biomarkers—spanning insecticides (organophosphates, pyrethroids), fungicides (dithiocarbamates, triazoles, succinate dehydrogenase inhibitors), and herbicides (phenoxy acids)—were calculated from two spot urine samples collected in 2017 and 2019. Associations between specific gravity-adjusted, log10-transformed biomarker-levels (ng/mL) and EF z-scores were estimated using multivariate linear regression, adjusting for agricultural setting, child and maternal characteristics, and household factors.
Results
Twelve of thirteen pesticide biomarkers showed widespread detection, with several (TCPy, 3-PBA, OH-TEB, ETU, and 2,4-D) detected in over 98 % of samples. Higher average levels of TCPy (β = −0.14; 95 % CI: 0.27, −0.01) and BCP (−0.08; −0.15, −0.02) were associated with poorer cognitive flexibility. Higher average levels of TCPy (−0.18; −0.31, −0.05), BCP (−0.08; −0.14, −0.01), cis-DCCA (−0.15; −0.31, 0.00), and OH-P (−0.09; −0.16, −0.03) were associated with poorer inhibitory control. No significant associations were observed for visuospatial working memory.
Conclusions
Findings suggest postnatal exposure to specific organophosphates, pyrethroids and triazoles may impair specific EF domains. Results highlight the need for biologically informed exposure assessments and targeted interventions in agricultural populations.
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