By Maile Matsimela, Digital Editor at African Farming
Dr Luthando Tiya moved from DNA analysis in forensics to studying how pesticides affect farm workers. Driven by a passion for protecting vulnerable people, he left the South African Police Service’s Forensic Science Laboratory for a new path that could make a real difference.
This journey culminated in a doctorate in pharmacology, awarded on Thursday, 11 December 2025 at Stellenbosch University, and groundbreaking research uncovering alarming truths about pesticide exposure in South Africa’s agricultural lands.
A Mission to Protect the Vulnerable
“Farm workers and nearby rural populations are particularly vulnerable to direct and indirect exposure to pesticides, while the broader public is affected through residues in food products and contamination of water sources,” explains Dr Tiya. He says this poses substantial risks to human health, biodiversity, and the health and balance of ecosystems.
Also read: Pesticide exposure affects developing brains
His research focused on the Western Cape, which is one of South Africa’s most agriculturally intensive regions. “Given that the Western Cape is one of the most agriculturally intensive regions in South Africa, we sought to investigate how such extensive agricultural activity might affect the health of farm workers,” says Dr Tiya.
Shocking Discovery: The Metabolite Crisis
Analysing blood samples from 258 people in farming areas, Dr Tiya’s team found pesticide residues in 30 samples, providing the first human exposure data for these chemicals in sub-Saharan Africa.
Most alarmingly, the study discovered that pesticide breakdown products often prove more dangerous than their parent compounds.
“When pesticides break down in the body, the resulting chemicals can be even more harmful than the pesticides themselves,” Dr Tiya explains. “Ongoing, low-level exposure – mainly caused by these chemicals – poses a greater threat than currently recognised.”
Laboratory tests showed shocking toxicity: chlorpyrifos breakdown products caused 100% mortality in test subjects, and other metabolites triggered severe disorders and developmental problems.
Beyond Farm Workers: Community Impact
Most concerning was discovering that exposure extends far beyond agricultural workers.
“My research showed that some people living in farming-intensive areas had herbicides or their breakdown products in their blood, indicating that the wider community was exposed beyond just farm workers,” says Dr Tiya.
Also read: Pesticides ‘essential part of farming’
The study revealed geographic patterns with detection rates varying from 5.6% in Ceres to 17.8% in Op Die Berg, with peak exposures during the May herbicide season.
“These findings raise concerns regarding the potential long-term health consequences for people exposed to pesticides, particularly on or close to farms,” warns Dr Tiya.
He notes that current legislation “largely focuses on pesticide registration procedures and application standards but provides limited consideration of cumulative environmental effects and insufficient safeguards for exposure to farms and surrounding communities”.
Call for Action
Given South Africa’s highest pesticide use in the Southern African region, Dr Tiya calls for urgent reforms:
- Stricter occupational safety standards;
- Buffer zones between agricultural and residential areas;
- Enhanced community health surveillance; and
- Evidence-based exposure reduction practices.
“The agricultural sector must implement evidence-based practices that reduce pesticide exposure, safeguard workers’ health and maintain sustainable productivity,” emphasises Dr Tiya.
Building Bridges, Not Barriers
Dr Tiya emphasises that his research supports agriculture: “This research is not intended to undermine the agricultural sector but rather to promote the safe and responsible use of pesticides, with the aim of protecting agricultural workers, surrounding communities and the broader ecosystem.
“For communities affected by pesticide exposure, my research demonstrates that health risks are tangible and quantifiable, and that targeted interventions, ranging from policy reforms to practical protective measures, can substantially mitigate harm,” he says.
Also read: Crop production: How to use pesticides safely
“I hope this research supports evidence-based regulatory frameworks, promotes the responsible use of pesticides and raises awareness within communities regarding environmental and occupational health risks.
“Collectively, these interventions can reduce human exposure, prevent long-term adverse health outcomes, and promote safer and more sustainable agricultural practices for all stakeholders.”
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