Health risk as chemical used to alter maize moisture readings

Workers dry maize in Elburgon, Nakuru County

Workers dry maize in Elburgon, Nakuru County in November last year. It has been established that some farmers are using a pesticide to alter the moisture readings of their maize.

Photo credit: John Njoroge | Nation Media Group

For over five years, Victor*, a farmer in Trans Nzoia County, has been applying a chemical powder to dry his maize whenever there are prolonged rains and a lack of sunshine.

He is among farmers and traders in the maize growing areas using a white powder known as Nova—which contains 2 per cent malathion and 0.2 per cent pytherin—to beat moisture meter readings. 

“This product was introduced in the market to tackle weevils, but many farmers realised it was not effective. Even though another substance was introduced in the market, we continued using it after we noticed that it also used to ‘dry’ our grains,” said a farmer.

He explained that half a kilo of the powder can aid in lowering the moisture content for 20 bags of maize.

“We have the issue of unpredictable weather patterns. There is inadequate sunshine so we use this substance. We apply in the morning at around 9 am and by 3 pm the moisture content will have gone down. We usually apply to grains that are sold in the market, not the maize that we consume at home,” disclosed the farmer.

Lab analysis

The Nation team was able to obtain samples of maize sold by traders on the borders of Kenya, Uganda and Tanzania for lab analysis. The samples were analysed at the biotechnology lab at the University of Eldoret.

Mr Kipkogei Chemitei, a research assistant at the university, said that the results showed that the powder immediately lowered the moisture meter reading by between 1.5 and 2 per cent.

“First, the substance absorbs moisture in maize, secondly, the substance itself is altering the functioning of the moisture meter,” explained the researcher.

Some traders and locals at Sarari and Isebania on Kenya’s border with Tanzania and Busia along the Uganda border complained that the maize laced with the powder is exposing them to serious health risks and called on governments to introduce stringent measures to halt its misuse.

“They use it on freshly harvested maize and it takes a few hours to dry. Most people don’t want to buy the maize due to health concerns,” said Happiness*, a female maize trader. “Two years ago, some people consumed maize dried with the substance and developed health complications. So many people were taken to hospital for eating the maize.”

“It is really easy to notice maize dried with this powder. Usually, maize dried with the substance has a certain smell and is sticky. Most buy it and then wash it, but others buy for flour processing, making it difficult to notice,” said Julius Mash, a trader at the Isebania.

Prof Julius Ochuodho, a plant pathologist at the University of Eldoret, explained that since the chemical only alters the readings, it may result in grains having high levels of aflatoxin caused by fungi. 

He added that the substance is not fit for human consumption since it’s intended to be used for seed dressing.

“This powder should be used only as an insecticide, not as a drying agent because it doesn’t dry the maize. There is a big risk of grains going bad,” said the expert. “It is a temporary measure because using this chemical cheats the machine that maize has a low moisture content level, which is not the case.”

Prof Ochuodho added: “Aflatoxins are a problem when consumed for a longer time. If we continue treating our grains with this substance, we find that many times the grains that millers have will have higher moisture content and therefore higher aflatoxin levels. When we continue feeding on these grains, we start having chronic diseases like cancer.” 

In 2021, the Kenya Bureau of Standards recalled some of the popular brands in the market due to high levels of aflatoxin. 

Ms Pamela Mwikali, a resident of Eldoret town observed that even though a packet of flour she bought had not expired, it was mouldy when she opened it, which raised their suspicions over the quality of maize grains.

Registered as insecticide

Pesticides Control Products Board (PCPB) Chief Executive Officer Esther Kimani said that Nova was registered for use in the country in 2013 as an insecticide to control weevils, including large borers and green borers in stored grains. 

“I don’t think in Kenya we can manage stem borers without using pest control. It is applied to manage large borers in post-harvest management of store grains,” said Dr Kimani, adding that the product should only be used for the purpose for which it was registered.

“I was informed that the pesticide’s carrier material can absorb water. Maybe farmers observed that once they treated their grains against weevils, the grains dried faster. However, we have no scientific data on the same,” said Dr Kimani. 

“We are going to investigate the claims. However, it might be difficult for us to regulate because a farmer may say that they applied grains in post-harvest management,” Dr Kimani said.

She explained that there is a need to sensitise farmers on the proper use of pesticides by following the instructions on the labels. 

“That is why we give safe doses because if overdosed, then there are side effects to consumers and effects to the environment. Farmers need to follow the recommendations given by PCPB,” said Dr Kimani.

Lack of access to drying and storage facilities has been cited as one of the biggest challenges for cereal farmers, pushing the unscrupulous into using the powder. Some farmers who use the powder say this helps them to lower labour costs—hiring workers to dry the grains under the sun.

Dr Moses Mwanje, the immediate former Busia County Agriculture executive, said that food safety requires collective measures to eradicate aflatoxin. “We encourage traders and farmers not to use uncouth means to dry their maize. We also need to ensure that action is taken against farmers and traders who use uncouth means to dry their maize.”