Are pesticides to blame for rising cancer burden?

A farmer spraying crops with pesticides. [Nanjinia Wamuswa, Standard]

There is a critical link between food safety and cancer prevention in Africa.

According to the World Health Organisation (WHO), a robust health system encompasses various elements, from clinical care facilities to home-based services, all aimed at promoting, restoring, or maintaining health.

This includes vital aspects such as health promotion, screening, education, clean water, sanitation, and food safety measures. With over a million new cases and 700,000 deaths annually, cancer poses a huge health challenge in Africa. Common cancers like breast, cervix, prostate, liver, and colon malignancies inflict suffering on patients and impose substantial financial burdens on households.

The mounting cancer burden is not solely attributable to improved detection but also indicates a genuine rise in incidence, largely due to increased exposure to various risk factors. Among these factors, pesticide use in agriculture emerges as a potential contributor. Animal studies have linked numerous pesticides, including herbicides, insecticides, fungicides, and nematicides, to elevated risks when exposure exceeds established thresholds.

Human studies have further associated different pesticides with various types of cancer, highlighting the complex interplay between agricultural practices and public health.

To illustrate how pesticides might heighten cancer risks, let’s consider two hypothetical scenarios:

In the first scenario, Jane, a Kenyan farmer, adheres to stringent EU pesticide residue limits while cultivating French beans for export. Compliance with regulations necessitates rigorous testing and adherence to recommended pre-harvest intervals (PHI) to ensure produce meets safety standards.

Imagine a second scenario. John, an onion farmer, manages four acres. Following heavy rains, which invite diseases and pests, John uses insecticides and fungicides on his crops. These chemicals require a two-week waiting period —known as the pre-harvest interval (PHI)—to ensure any residues diminish to safe levels. However, four days after spraying, John encounters a lucrative opportunity to sell his produce. He decides to harvest and sell 79 tons of onions, which arrive in city markets only a week after the pesticide application—seven days short of the recommended PHI.

This scenario highlights not only the pressures farmers like John face to capitalise on market opportunities but also raises critical concerns about food safety and consumer health that need to be addressed.

Now, consider your own experience. When we think about our daily meals, which often include onions and other locally grown produce, we must consider the safety of these ingredients. Unlike in Europe, where farm products undergo extensive testing under robust and scientifically validated protocols, local produce may not be subject to such rigorous scrutiny. 

This raises an important question: could the food we consume daily contain harmful levels of agricultural chemical residues? These residues, potentially carcinogenic, could be contributing to the rising cancer rates we are witnessing. Our health system must investigate these concerns and ensure the safety of the food supply, protecting public health and consumer trust.

To address this, we must start with fundamental changes, particularly in the regulatory framework. The 2013 National Food Safety Policy from Kenya’s Ministry of Health underscores the importance of Food Safety Acts across Africa.

Making food safety a priority by governments of Africa’s nations is imperative.

As part of their commendable efforts to advance global health, organisations like the WHO, Africa CDC, and Amref Health Africa have the opportunity to provide technical assistance to African governments to strengthen the food safety regulatory environment.

A good practical beginning is for governments and these organisations to support studies on the status of food safety in Africa.

-Dr Wanjuki and Ms Indalo work at Amref Health Africa in Kenya