Tests show dangerous levels of toxins in foods sold in Nairobi

Monday January 11 2016

Scientists have sounded the alarm over the safety of a number of foods sold in Nairobi, including bananas, apples, poultry, sukuma wiki and milk.

They say the foods could be laced with toxic chemicals.

The chemicals are either mixed with feeds for poultry, added to dairy products, used for deep frying, hasten ripening of fruits or as preservatives.

Tests on samples of foods in markets and supermarkets have shown dangerous levels of toxins like calcium carbide, hydrogen peroxide, polychlorinated biphenyl-laden transformer oil, formalin and lead.


Public health experts and medical practitioners last week told the Nation that the chemicals were responsible for a litany of ailments and complications.

French fries, popularly known as chips, and mandazi made in various estates were found to have transformer oil. The oil can be used for a long time without getting contaminated and thus saving vendors as much as 40 per cent of costs.

A woman who requested anonymity told the Nation that before she got a got a job this month as a school bursar, she used to prepare chips using the oil.

“I used to buy 10 litres for Sh7,000 and it would last almost three months,” she said.

“The supplier, in Uthiru, would deliver it in cooking oil containers with flour and no one would notice anything.”

Mr Anorld Muendo, who makes and distributes mandazi in Roysambu, Mwiki, Kasarani and Zimmerman estates, said the use of transformer oil is rampant.

“Transformers are vandalised for the oil. Kenya Power employees also steal the oil and sell to traders,” he said, adding that mandazi fried using the oil has an attractive golden-brown hue.

Consumption of the oil could lead to digestive system infections.

Dr Esther Maina, a biochemist at the University of Nairobi, said the degree of harm depends on the frequency of consumption and volumes.


Transformer vandalism, which costs Kenya Power millions of shillings every year, is an indicator of the illicit oil business.

In 2014, for instance, replacing transformers cost Kenya Power more than Sh400 million, about seven per cent of its net profit.

But it is not just the popular fries that could be silently killing Kenyans.

Lab tests on fruits sold in Mombasa and Nairobi markets indicated the presence of calcium carbide, which traders use to hasten the ripening of their stock overnight.

Traces of the chemical were found in ripe bananas, oranges and mangoes sold on the streets of Nairobi.

Samples from three leading supermarkets and groceries in Nairobi and Mombasa tested positive for the poisonous chemical.

Calcium carbide is used for welding and manufacture of plastics.

Dr Diana Ogutu, a medical practitioner, said consumption of the chemical could lead to throat sores, coughs, wheezing and shortness of breath and that these can occur soon after exposure.

“More exposure may cause a build-up of fluids in lungs,” Dr Ogutu said, adding that high amounts of calcium carbide could weaken the body and lead to breathing complications.

Dr Daniel Sila, a food science technologist at Jomo Kenyatta University of Agriculture and Technology said regular exposure to the chemical could lead to peptic ulcers.

“Calcium carbide is hazardous to the human body as it contains arsenic and phosphorus. It is banned in many countries but it is freely used in India, Pakistan, Bangladesh and Nepal,” Dr Sila said.

He accused the Pesticides Control Products Board of negligence as it has not blacklisted calcium carbide despite its serious health risks.

According to Dr Jane Njiru, a scientist with the board, banning the chemical is not easy.

“If people are diverting a product for other uses other than the registered one, then it is misuse. It is difficult to ban a product because of that,” she said.

In Kenya, only ethephone and etherel have been approved by the board for ripening fruits.


Scientists also caution that most of the sukuma wiki sold in Nairobi could contain dangerous amounts of lead.

The lead in the vegetable, grown on river beds and near sewers, might cause decreased or stunted growth in children, learning disabilities and kidney damage, says Dr Wycliff Guto of Christa Marriane Hospital.

“Lead can also cause brain damage, infertility, high blood pressure, memory loss and muscle and joint pains in adults,” he added. 

To make matters worse for Nairobi residents, non-packet milk sample tests by Kenyatta University nutrition students revealed higher-than-recommended amounts of hydrogen peroxide — used as a preservative — and formalin, also used to preserve bodies in mortuaries.

Dr James Kinyua said ingestion of small amounts of hydrogen peroxide would have no toxicological effects due to rapid decomposition of the chemical in intestines.

“But ingestion of higher concentrations — more than six per cent — can result in burns,” he added.

These revelations raise public health concerns, especially in the wake of a steep rise in the number of cancer cases.

Cancer is the third killer disease in Kenya. According to Nairobi Cancer Registry, 38,544 new cases were diagnosed in 2012, with 26,941 deaths occurring the same year.

A source at Kenya Plant and Health Inspectorate, said the agency does not have the equipment to test for some of chemicals in imported foods.

Apart from various feeds used to hasten growth of poultry, other peculiar feed has been added to the list; antoretroviral drugs.

The ARVs are meant to increase the appetite of chickens and help them gain and maintain weight. These chickens are sold to restaurants.

Eating chicken fed on ARVs is indirectly taking the HIV drugs, says Dr Humphrey Mbugua of Kenya Poultry Breeders’ Association.

ARVs work through suppressing or killing virus particles, thus reducing the destruction of CD4 cells.