Dr. Omar El-Agnaf, Executive Director of Qatar Biomedical Research Institute, Hamad Bin Khalifa University, argues that regional governments should act swiftly to ban chlorpyrifos, a pesticide that causes developmental risks in children.


Independent science recently sounded the alarm about the widely used pesticide chlorpyrifos, triggering a call to action for policymakers across the globe, so I was interested to read that the current US administration is refusing to ban it.

Mounting scientific evidence shows that the exposure of pregnant women and infants to the pesticide increases the risk of neurodevelopmental disorders, such as autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD), even at low-level exposures.

Meanwhile, California has pushed ahead and banned chlorpyrifos from agricultural use, while Hawaii, New York, Oregon, Connecticut, and New Jersey have approved bans or have bills under consideration to take it off the market. Several countries, including South Africa, Palestine, Saudi Arabia, and Sri Lanka, have already banned its use.

Given the weight of scientific evidence, I would like to see more countries following their lead, and I would especially advocate a ban on all uses of chlorpyrifos being extended throughout the Middle East and North Africa (MENA) region.


On the market since 1965, chlorpyrifos is touted by farmers as one of their most effective pesticides and is currently registered for crop protection in more than 100 countries. In California, until its recent ban, it was used by farmers to kill pests on 60 different crops, including oranges, grapes, and almonds.

The US banned chlorpyrifos as a home insecticide in 2000 because of findings suggesting neurotoxic threats and placed “no-spray” buffer zones around sensitive sites, such as schools, in 2012.

But it is only in recent years that the Environmental Protection Agency (EPA) has sought to end its use in agriculture, based on similar findings of neurotoxicity, and advocacy for its ban is under way in both the European Union and Australia.

These policy shifts are disrupting a long-established regulatory framework around pesticide use and signal the vital importance of science-based policy decisions in public health.

What Is Chlorpyrifos & How Are We Exposed to it?

This organophosphate pesticide comes from the same chemical family as sarin gas. It works by blocking the enzyme acetylcholinesterase, which the brain needs to control acetylcholine, a neurotransmitter mediating communication between nerve cells. It is these neurological effects that pose a high risk for children as their brains and nervous systems develop.

People can be exposed to chlorpyrifos when breathing dust that drifts from nearby fields into homes and schools. Chlorpyrifos readily evaporates from leaf and soil surfaces to become airborne and, once in this gas form, can migrate. Farm workers are at risk through on-the-job exposure.

After harvesting, traces of the pesticide are left as residues on fresh foods, and for this reason, I strongly advise to always peel or thoroughly wash fruits and vegetables before eating to reduce these residues.

Brain-Damaging Effects Even at Low Level Exposures

Findings from recent studies suggest that earlier chemical evaluations based on toxicity testing on animals were insufficient and that the restrictions on chlorpyrifos to date were not strict enough.

Multiple epidemiologic studies show that prenatal exposure to chlorpyrifos elevates the risk of developmental effects in children and fetuses, such as ADHD and autism. One of the most influential is a 2016 study by Columbia University’s Center for Children’s Environmental Health, which showed children with the highest chlorpyrifos concentrations in their umbilical cord blood to have differences in volume in those brain regions responsible for attention, receptive language processing, social cognition, and regulation of inhibition.

In 2016, the EPA concluded that these epidemiologic studies provided sufficient evidence that organophosphate pesticides can interfere with brain development at levels previously thought to be safe.


How Biomedical Research Can Help

The extensive epidemiologic literature is clear, and scientists have called for “vigilance on the scale required for medicines” to assess the effects of pesticides in the environment. This challenging task has social, political, ethical, economic, and legal implications.

An even more recent study reported in the British Medical Journal recommended that the exposure of pregnant women and infants to several common agricultural pesticides with potential neurodevelopmental toxicity (among them, chlorpyrifos) should be avoided as a preventive measure against ASD.

Moving forward, we need long-term follow up studies for a better understanding of the effects of all classes of pesticides, including those linked to brain disorders or cancer, and to offer newer perspectives to health policymakers in the region.

Research by the Qatar Biomedical Research Institute (QBRI), which is part of Hamad Bin Khalifa University, a member of Qatar Foundation, focuses on prevalent diseases affecting the Qatari population and the region, and emerging research priorities with a critical impact on Qatar and globally. ASD, neurodegenerative diseases, and cancer are among the diseases being studied by two of the three research centers at QBRI. Our work at QBRI is aimed at improving healthcare through innovation in prevention, diagnosis, and treatment.

QBRI’s scope and capabilities can make an important contribution to the long-term studies needed to identify and develop appropriate health and environment strategies as part of an effective interdisciplinary approach to resolving and mitigating the public health risk posed by pesticides.

Our research outcomes and the deep understanding of these prevalent diseases by QBRI researchers and scientists can enhance the understanding of policymakers when formulating action plans to tackle public health menaces.

What Is the Next Step?

The science regarding the neurotoxic effects of chlorpyrifos is unequivocal, and taking the appropriate action as soon as possible should be the highest priority for regional and global policy makers–we ignore the findings at our peril.

A diet rich in fruit and vegetables is an essential part of a healthy lifestyle, regardless of whether they are conventionally or organically grown, which is why more must be done to eliminate this pesticide from our food chain altogether.

In my view, there are two immediate steps to take:

  1. We need immediate action to ban those pesticides that have been scientifically documented and proven to be harmful, starting with chlorpyrifos.
  2. We need strict regulations and guidelines to enforce the responsible handling of all pesticides. Qatar imports the bulk of our fresh vegetables and fruit from the MENA region, giving us a vested interest in spreading awareness on how mishandling impacts our health. This extends to the use of pesticides inside homes as well, where overuse or misuse is dangerous for pets and for humans.