At 7 am on Wednesday, technicians deployed from the Rapid Bioassay of Pesticide Residues Laboratory Unit in Kalimati collected samples of mustard greens for testing.

The laboratory gave a report within 30 minutes, showing an excessive level of hazardous pesticide—organophosphate—in the leafy vegetable, which is very popular among Nepali People. Organophosphates are commonly used by farmers to kill insects and larvae quickly by disrupting their nervous system.

“We rushed to the vegetable seller to prevent him from selling the greens,” said Bimala Ghimire, a technical assistant serving at the laboratory. “However, the vegetable seller had already returned home after selling all the pesticide-laced mustard greens.”

This is not the first time vegetables with excessive pesticide levels reached customers before test results came in or authorities concerned could intervene.

Lab technicians collect samples of vegetables on a random basis and send them for testing, but traders or farmers are not prohibited from selling the produce until lab reports arrive.

According to officials, the leafy vegetable brought to Kalimati from the Dolakha district contained over 80 percent organophosphate pesticide, far exceeding the safe limit. If pesticide levels exceed 45 percent, the vegetable must be destroyed due to health risks.

Pesticides are commonly used to kill insects, fungi, weeds and diseases that damage plants and crops. Farmers rely on pesticides to protect crops from pests. According to the World Health Organisation, pesticides can be potentially toxic to humans and can have both acute and chronic health effects depending on the quantity and ways in which a person is exposed to them.

Doctors say long-term consumption of vegetables and fruits with high levels of pesticides can lead to renal failure, heart and lung diseases, mental health problems and cancer. Consumption of such fruits and vegetables may also affect pregnant women and harm foetuses.

“Chronic exposure to organophosphate could lead to muscle weakness, peripheral neuropathy, behavioural change including confusion, anxiety, psychosis, hypertension, and weight gain, among other problems,” said Dr Akritee Pokhrel, assistant professor at the Department of Pharmacology of the Institute of Medicine under the Tribhuvan University. “Long-term exposure can also lead to renal failure, heart and lung diseases and cancer among others.”

The Department of Agriculture carries out tests for organophosphate and carbamate pesticides in fruits and vegetables on a regular basis from various labs across the country.