Toxic Food Series: How banned agrochemicals infiltrate food chain

Highly hazardous pesticides banned in parts of Europe and North America over links to cancer, organ damage and endocrine disruption are finding their way into Nigeria’s food chain, exposing gaps in chemical regulation, market surveillance and enforcement.

Nigeria accounts for more than a third of West Africa’s pesticide imports, which nearly doubled from 218,948 tonnes in 2015 to 437,930 tonnes in 2020, according to the Alliance for Action on Pesticides in Nigeria (AAPN).

As reliance on agrochemicals has increased, regulatory oversight has struggled to keep pace. Despite bans imposed by the National Agency for Food and Drug Administration and Control (NAFDAC), prohibited chemicals remain available to farmers and traders for weed control, pest management and produce storage.

“The use of hazardous pesticides and agrochemicals by farmers and traders to protect crops, control weeds and store food products is silently poisoning Nigerians,” Joseph Akinneye, a professor of biology at the Federal University of Technology, Akure, told BusinessDay in January.

A major pathway through which banned substances enter the food chain is the illicit blending of chemicals in domestic markets. Products sold under familiar brand names may contain unlisted or prohibited compounds, making it difficult for buyers to establish what they are applying to crops or using to protect stored produce.

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Laboratory analyses conducted by the Centre for Food Safety and Agricultural Research (CEFSAR) found that commercial formulations sold under popular trade names, including Sniper, traditionally associated with dichlorvos (DDVP), had been adulterated with hazardous, unapproved substances, according to the centre.

“When you subject what is sold in the market to chemical analysis, we find that vendors or suppliers have added banned, far more hazardous chemicals to make them more efficacious, including chlorpyrifos and paraquat,” said Qrisstuberg Amua, a professor of biochemistry and executive director of CEFSAR.

“These are banned chemicals on NAFDAC’s list, yet they continue to find their way into the consumer food space.”

Amua said the deliberate addition of prohibited pesticides to commercial formulations could increase the health risks associated with exposure to the products.

“NAFDAC is simply not doing enough. How come these things find their way into Nigeria?” he said.

Mojisola Adeyeye, NAFDAC’s director-general, raised concerns in an October 11 note about the illegal movement of banned and unregistered pesticides across Nigeria’s borders, warning that chemicals lacking the required regulatory assessment could enter local markets through informal distribution channels.

Adeyeye said the agency had seized banned agrochemicals worth more than N800 million across Ogun, Ondo, Osun and Oyo states in 2025 as part of efforts to curb the circulation of unsafe agricultural chemicals.

She said bans on paraquat, chlorpyrifos and atrazine took effect on January 1, 2024, November 1, 2024 and January 1, 2025, respectively, with applicable phase-out grace periods ending on January 1, 2026.

BusinessDay’s survey of major pesticide markets in Kano, Kaduna and Lagos found products containing dichlorvos, mancozeb, imidacloprid, thiamethoxam, paraquat, chlorpyrifos and atrazine on the shelves of agro-dealers and open-market traders.

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“We buy these chemicals from our suppliers and our suppliers are not hiding to sell them,” an agro-dealer in Kano, who spoke on condition of anonymity, said, adding that banned agrochemicals remained readily available when needed.

Contaminated staples exceed safety limits

The risks associated with pesticide misuse extend beyond the chemicals sold in markets to the residues left on food crops.

The 2021 Pesticide Atlas report classified nearly two-thirds, or 66 percent, of the agrochemicals identified in Nigeria as highly hazardous.

Tests on locally produced food have also found pesticide residues at levels exceeding international safety thresholds. Cowpea samples contained dichlorvos concentrations of up to 0.3 milligrams per kilogram, 30 times the European Union’s maximum residue limit of 0.01 milligrams per kilogram cited in the report.

Permethrin residues have also been detected in tomatoes. The chemical has been assessed by the United States Environmental Protection Agency for its potential health effects, although the risks depend on the level and duration of exposure.

AAPN data indicate that all 17 highly hazardous pesticides identified in its assessment as banned in other jurisdictions remain in circulation among Nigerian farmers.

Although NAFDAC has banned six of the 17 chemicals, weak market surveillance and enforcement continue to undermine efforts to prevent prohibited substances from reaching farmers and traders.

Environmental risks extend beyond the farm

The risks associated with hazardous pesticides are not confined to crops. Their application can also contaminate surrounding ecosystems, particularly where chemicals enter water sources through agricultural runoff.

“Food contamination begins right in the field, depending on farming practices and the volume of pesticides applied,” Amua said.

He warned that excessive application and repeated exposure to hazardous chemicals could increase the risk of adverse health effects, including respiratory problems and hormonal disruption, depending on the substances involved and the extent of exposure.

Because some pesticide residues persist in the environment, agricultural runoff can carry them into streams, wells and other water sources, potentially exposing people who do not handle the chemicals directly.

“The environment is no longer safe,” Amua warned. “Innocent citizens who never applied a single pesticide fall victim simply by drinking water extracted from a borehole or a river contaminated by agricultural runoff.”

He added that people applying pesticides could also be exposed to harmful substances through direct contact or inhalation.

Organic pesticides offer an alternative

Experts have urged governments at all levels to invest in organic agriculture and agroecological farming as alternatives to production systems that depend heavily on conventional agrochemicals.

Jude Obi, a professor and president of the Association of Organic Agriculture Practitioners of Nigeria (NOAN), called for greater public awareness and advocacy to encourage farmers to adopt organic agricultural practices.

Obi said some countries were increasing their use of organic pesticides while reducing reliance on conventional agrochemicals because of their potential health and environmental benefits.

However, wider adoption of alternatives will require investment in farmer education, access to effective pest-management methods and stronger extension services.