The pesticide responsible for the death of 23 Indian children is already banned in many countries; the World Health Organization (WHO) has asked India do the same.
WHO considers the nerve poison called monocrotophos to have "high-acute toxicity," Reuters reported.
The United Nations health agency has been urging India to ban the substance since 2009. They also warned many pesticide containers were not being properly disposed of, and some were even being used to store food and water.
"Many pesticide containers, because of their sturdiness and look, are often later used to store objects, food grains and water, and sometimes even medicines," David Coggon, a professor of occupational and environmental medicine at Britain's University of Southampton, said.
School lunches contaminated with the pesticides caused a group of children to fall ill almost immediately.
The free meals were a part of India's Mid-Day Meal Scheme, which was started as an effort to get more children in school. The program has gained a reputation for employing poor hygiene.
The cooking oil used in this particular meal contained a chemical belonging to a category called organophosphates.
"Basically they are nerve poisons," Coggon said. "They interfere with transmission between one nerve and another, or with transmission between nerves and muscle cells."
The WHO said swallowing only 120 milligrams of monocrotophos (the size of about five grains of rice), can cause death.
Symptoms of monocrotophos poisoning include "sweating, nausea, vomiting, blurred vision and hyper-salivation, or foaming at the mouth."
The substance is commonly used to eliminate crop-harming pests found in cotton and sugar cane.
Countries such as "Australia, Cambodia, China, the European Union, Indonesia, Laos, Philippines, Sri Lanka, Thailand, Vietnam and the United States" have completely banned the lethal pesticide.
"Its low cost and many possible applications have kept up demand in India despite growing evidence of its negative impact on human health," the WHO said in a statement.
