Study finds soils laced with cancer causing chemicals

Soils in parts of Kenya are contaminated with cancer causing chemicals; some already restricted for use, shows a news study.

A study on soils from Kapsabet, Nyeri and Voi towns shows concerning levels of contamination with cancer causing DDT and the pesticide lindane.

The researchers collected and tested the soils around the three towns and found them contaminated with the two chemicals.

Then they assessed the cancer risk posed by presence of these pollutants to human beings.

In their work published on August 15 in the International Journal of Environmental Research and Public Health, they report that the pollutants are a cancer risk to humans.

“The cancer risk assessment showed values close to the set risk level, suggesting the likelihood of exposure to cancer was not low enough, and control measures need to be established,” concluded the study.

The study by Teresiah Mungai and Jun Wang of the Chinese Academy of Sciences and the JKUAT-based Sino-Africa Joint Research Centre, says the DDT contamination in the three towns was from recent chemical applications.

The study, the authors say is indication of what may be happening in other parts of the country especially in centres near agricultural and manufacturing activities.

Among the three towns, soils from Kabsabet was most contaminated with lindane whereas Voi had the highest concentration of DDT.

Contamination in Kapsabet was linked to high use of fertilisers and pesticide in extensive maize farming and from tea factories while Voi was mainly associated with sisal farming.

DDT contamination was also significant in Kapsabet thought to have been brought in through soil erosion from recent usage in malaria control in western Kenya.

Poor waste disposal

In Nyeri, contamination was linked to tea and coffee farming and presence of several manufacturing industries in the town and poor waste disposal.

DDT was banned as a pesticide worldwide under the Stockholm Convention in 2001 after it was discovered to be dangerous to wildlife and the environment. It had also been banned in Kenya in 1985.

In 2015, DDT and lindane were listed by the World Health Organisation (WHO) as possible carcinogens.

The chemicals have been linked specifically to cancers originating from the system that rids the human body of toxins, (lymphatic system) testicular and liver cancers.

However around 2010, pressure from donors to the Ministry of Health saw Kenya import DDT for control of malaria mainly in Western Kenya.

The importation had been opposed by the agricultural sector on grounds that DDT could turn out to be a health hazard.

This has had catastrophic consequences, with malaria mosquitoes becoming resistance to DDT and the chemical recently found to have extensively polluted agriculture soils, water and the environment in Western Kenya.

Lindane before its ban in 2015 was a popular hair and skin shampoo as well an agricultural pesticide in Kenya.

Though supposed to be restricted in Kenya, lidane is contained in some imports especially from Asia like Kwell, Scaboma Lotion, Scarab Lotion, Liceoma Lotion or Gamna Benzine.

It is normally used for treatment of human lice or the skin infection called scabies, a highly itchy and infectious disease.

The product is also used for insect control and seed dressing in agriculture but for some years, this use has been restricted in most countries including Kenya.

“Lindane is a widely used chemical for seed treatment in Kenya, hence explaining its abundance in the soil,” says the study.

An earlier study among women at a maternity hospital in Nairobi carried out by Shem Wandiga of the University of Nairobi found significant levels of lindane in breast milk collected from the mothers.

While DDT is indicated by the Pest Control Products Board to be banned in Kenya, the same has registered several agricultural products that contain DDT.

Last year the Sino-Africa Joint Research Centre published more data showing high contamination of local agriculture soils.

The team had sampled soils at various points between Kiambu and Mombasa and found high contamination with cancer causing chemicals.

“We identified recent and historical use of DDTs and lindane in collected samples,” said the study published in the Bulletin of Environmental Contamination and Toxicology.

The difference between the then and the current study is that in the latest work the authors also assessed the possible risk presented by the contamination.

“A set of guidelines should be put in place to mitigate and control the use of such chemicals in soils. The environmental authority in Kenya should also ensure that prohibited chemicals are no longer in use,” says the study.