Nairobians may have to be very keen on what they buy or consume from restaurants and take away joints.

Scientists have sounded the alarm over the safety of a number of foods sold in Nairobi, including bananas, apples, poultry, sukuma wiki and milk, that could be laced with toxic chemicals.

The chemicals are either mixed with poultry feeds, 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.

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

Lab tests on fruits sold in Mombasa and Nairobi markets indicated the presence of Calcium Carbide (used for welding and manufacture of plastics) which traders use to hasten the ripening of their stock overnight.

Traces of the chemicals 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.

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.