Paraquat, A Banned Toxic Chemical, Is Leaking Into The Global Food Supply Chain

Nearly two years after Nigeria banned paraquat, the highly toxic herbicide continues to be sold openly, an investigation by The Xylom reveals. If large economies like the United States and Malaysia strictly enforce the Stockholm Convention against the use of harmful pesticides, could it bring change in Nigeria? 

Half-used bottles of red-labelled herbicide still sit on the floor in Yakub Ahmad’s living room. Every time he looks at them, he remembers the day he almost died.

In April 2024, as rains spurred the growth of stubborn weeds, then-27-year-old Ahmad, a farmer from Ilora in Oyo State, Nigeria, carefully sprayed Gramoxone — a fast-acting herbicide that scorches weeds within a day – on his one-acre maize crop. He was mindful not to let even a drop touch the crop; a few stray drops had withered the entire crop in 2022. 

A bottle of Gramoxone costs ₦5,000 (equivalent to $3.4), while he would have to shell out anywhere between ₦58,000 and ₦73,000 (equivalent to $40–$50) to hire a week’s worth of labor to get rid of those weeds. But this time, there had been a leak in the bottle.  The chemical had trickled down his abdomen to his private parts. “After [working on] the farm that day, my body started tingling,” Ahmad recalls. “I had a burning sensation. I couldn’t sit or stand until I was rushed to the hospital.”  

He was treated for skin burns at the hospital, yet more than a year and a half later, a numbness prevails in his groin and stomach.  Ahmad still continues to use the herbicide in his crop, as it is the cheapest herbicide option. 

Banned only on paper

Ahmad is not the only one paying the price for choosing toxic and persistent organic pollutants such as Gramoxone. In January 2024, Nigeria's National Agency for Food and Drug Administration and Control banned paraquat, the man-made organic chemical sold under brand names such as Gramoxone, Parazone, and Quick-Quat, due to the severe risks it poses to human health, animals, and the environment. 

A view of Yakub Ahmad’s fields.  (Abdullahi Jimoh/The Xylom)

However, an investigation by The Xylom at three agro-chemical shops in Ilora found that paraquat, along with other banned chemicals, continues to be sold, signaling poor enforcement. Often imported illegally and relabelled under new trade names, a one-litre bottle of Gramoxone costs around ₦5,000 (equivalent to $3.4) in these shops. 

The demand for the product increases steeply during the rainy season. There seems to be no restriction on the quantity sold. An employee from one of the shops said that “people can buy a carton at once.” Another employee said that his employer just bought a new set of Gramoxone because it's fast-selling.

Our findings also show that cassava farmers are often compelled to use Gramoxone, even though it hinders the growth of the sprouts. 

Government raids are few and far between. On April 25, 2025, the National Agency for Food and Drug Administration and Control raided 16 outlets across Oyo, Ogun, and Ondo states for selling banned agrochemicals, including paraquat. “During the operations, over 16 outlets were inspected, resulting in the seizure of 551 cartons of banned pesticides, estimated at over ₦800 million,” the agency mentioned in a Facebook post. The agency raids shops only sporadically, after receiving complaints from the general public.  In the past year, there have been only three such raids.  The agency seized counterfeit agrochemicals in Bauchi in November 2024 and carried out a similar crackdown in Sokoto markets in July 2024.

Dr. Aminu Zakari from the Center for Climate Change and Environmental Studies in Nigeria said that the agency is not stringent in implementing the ban, hence the chemicals can be locally produced or smuggled into the country. 

The Xylom reached out to the National Agency for Food and Drug Administration and Control regarding the enforcement of the paraquat ban and the penalties for violations, but the agency has not responded.

Used widely on cassava and maize farms, Gramoxone was introduced by the British firm Imperial Chemical Industries in 1962. (Abdullahi Jimoh/The Xylom)

The hidden cost

In 1994, an adolescent girl from Ibadan, Nigeria, died from respiratory failure due to extensive interstitial and intra-alveolar fibrosis after ingesting paraquat. In 2022, three people died, and eight others were hospitalized in Nigeria after eating pesticide-contaminated beans, according to Daily Trust.

A 2014 memorandum by the United States Environmental Protection Agency reported two deaths in children due to accidental ingestion of Gramoxone.  

“When a pollutant enters human tissue, it begins to accumulate before expressing its toxic effects — that’s why [such chemicals] are called persistent,” says Michael Odey, environmental toxicologist at the University of Calabar in Nigeria, adding that a major accumulation may trigger cancer and cardiovascular diseases.  Odey said that children and the elderly are vulnerable because their bodies metabolize these substances more slowly.

Globally, researchers estimate that about 1.4 million tons of pesticides are used each year, leading to 385 million cases of acute poisoning and 11,000 deaths annually. 

Beyond impacting human health, it also harms the soil, plants, and wildlife. “Paraquat dichloride, present in Gramoxone, can persist in the soil for several months, depending on rainfall, temperature, and soil type,” Odey explains. “During that period, residues can leach into groundwater or be taken up by crops. They also harm earthworms, pollinators, and other soil-dwelling organisms essential for nutrient recycling. Over time, this disrupts the ecosystem balance, leading to declining soil fertility, reduced crop quantity, and long-term productivity loss.”

Reminiscent of the rashes on the hands of 43-year-old farmer Mallam Qozeem Isa, who used Atrazine without gloves. (Abdullahi Jimoh/The Xylom)

In Africa, where agriculture comprises about half of the continent’s GDP and employs nearly half of the population, the use of agrochemicals can be highly intensive.

In Nigeria, Africa’s second-largest maize producer, farmers use herbicides without protective gear, exposing themselves to fumes and toxins that can cause dermatitis, chronic eczema, and organ damage. Five years ago, Mallam Qozeem Isa, a 43-year-old cocoa and yam farmer from Iwo, Osun State, handled Atrazine with his bare hands, believing that rinsing with sand and water would neutralize its effects. “I did it out of ignorance,” Isa says. “After a few days, I began to feel itching on the back of my hands, and rashes appeared. Later, the skin peeled off.”

Cases like Isa’s are increasingly common, says Dr. Mahmoud Abubakar, senior registrar at the department of family medicine, Federal Teaching Hospital in Kebbi State. “Skin irritation, blisters, and burns caused by these chemicals can develop into systemic intoxication,” he explains. “In severe cases, they affect internal organs, the cardiovascular system, or even the brain.”

A shared risk

By completely banning paraquat, Nigeria has taken a stronger stance than the United States, which merely restricts its use to certified applicators. However, weak enforcement has severely undermined the ban, with reports of the chemical still entering the country illegally, particularly from China.

“Countries that fail to ratify the Stockholm Convention contribute indirectly to global contamination. Africa has become a dumping ground for chemicals others have banned.” -Michael Odey, environmental toxicologist at the University of Calabar in Nigeria.

In 2001, over 180 countries signed the Stockholm Convention, a global treaty aimed at eliminating or restricting the production and use of persistent organic pollutants. It came into force in 2004, setting a global framework for safer chemical management. The U.S. signed the treaty in 2001 but never ratified it, citing concerns that it lacked the full legal authority to enforce all its provisions. Malaysia, the second-largest importer of Nigerian cocoa, has yet to finalize its National Implementation Plan. 

“When major economies such as the United States and Malaysia don’t fully ratify the Stockholm Convention, it weakens global enforcement,” says  Aminu Zakari from the Center for Climate Change and Environmental Studies. “These chemicals continue to move through international supply chains and often find their way into countries with weaker monitoring systems like Nigeria.”

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The health burden doesn’t stop at Africa’s borders; it flows back through global food trade. According to the U.S. Department of Agriculture, between 2023 and 2024, global maize production reached 1.23 billion metric tons, with Nigerian exports increasingly entering international supply chains. And toxic agrochemicals can remain in soil and water for years, making the crops harvested in such soil risky for human consumption.

If pesticide residues persist in these exports, the impact can ripple across importing countries.

“This is not a Nigeria problem; it’s a global food chain problem,” Abubakar said.

Organizations like Alliance for Action on Pesticide in Nigeria are informing farmers about the health risks of toxic agrochemicals for farmers. 

But the onus should lie on the national agencies to educate farmers. “The first line of defense is knowledge,” said Dr. Odey. “Farmers must understand what they are handling, and governments must ensure these products don’t reach their hands in the first place.”

Back in Oyo, Ahmad’s scars may have faded, but his memory hasn’t. “I just wanted my maize to grow,” he said quietly, “Now, I know the danger, but if we stop using these chemicals, how do we feed our families?”

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