The problem of satisfying the dietary requirements of a growing world population is becoming increasingly acute. Foods which make a significant contribution to the food balance sheet for the average Kenyan include meat, milk, cheese, chicken, pork, honey, beeswax, eggs, fish and other animal products. Others are crops such as spinach, strawberries, grapes, green beans, tomatoes, cucumbers, watermelon, maize, soy, wheat, oats and fruits
During production of these foods, antibiotics, pesticides, fungicides, hormones and chemicals (which I will henceforth refer to as drug inputs) are needed. Use of the drug inputs in livestock, fish and poultry improves the rate of weight gain, improves feed efficiency, or prevents and treats diseases. The inputs are also used to kill pests and weeds during livestock and crop production.
Without the drug inputs, farmers would produce less food, the quality of food supply would be decreased, storage life of some fresh foods would be reduced, and some food would be less safe because it would contain harmful bugs.
But the use of the drug inputs also comes with a health and environmental risk associated with residues of the drug inputs that remain in the tissues of treated crops, fish, chicken and food animals. These residues are eventually consumed by man and are absorbed by our bodies and metabolized to harmful products.
This then means that, on the one hand, there is a benefit of improved production using the drug inputs, while on the other hand there is a risk of consuming residues left over in the foods that we eat. The public health concerns that are associated with consuming the residues may include long or short term allergic reactions, antibiotic resistance and toxicity, deformed embryos and cancers.
As an example, when bacteria become resistant to antibiotics that were used during production of the chicken, livestock and their products that we fed on, this means that when we become sick due to infection by these bacteria, the antibiotics that are prescribed to us will not work because the bacteria are already resistant to the antibiotics. This will in turn result in treatment failures, increased severity of infections, and in some cases death.
Another example is when the residues of pesticides used on the farm to kill weeds and to kill plant and animal pests like worms, weevils, fungi, ticks, fleas and lice, seep and remain in the soil, underground water, and air for long periods, especially where unused and expired pesticides are not properly disposed of and are poorly stored. We become exposed when we consume crops that are grown in the contaminated soil and water, or when we consume products of livestock which grazed on pasture grown on the contaminated soil.
Another example is when farmers refuse to adhere to prescribed regulations for animal husbandry and they resort to employing unethical farming practices driven by the desire to shorten the rearing period, enhance weight, reduce costs and increase profits. They use antibiotics and hormones for non-curative purposes such as fattening and growth promotion. This in turn is responsible for unhealthy food products finding their way to consumer shelves.
Another example is when bees visit, and collect nectar and pollen from, flowers of plants which have been sprayed with pesticides. This then means that the honey may contain residues of the pesticides used. Honey also gets contaminated by unscrupulous business people who adulterate honey by adding such things as tea leaves, sugar, and molasses. They do this because the demand for honey and honey products far outweighs the supply.
Yet another example is when we consume fish that contain dangerous levels of pesticide residues arising from pesticides that flow into ponds, rivers and lakes from the surrounding farms.
And also when we consume meat from animals that graze on city garbage dumps, which may contain dangerous levels of residues of antibiotics, pesticides and heavy metals such as lead, zinc, copper and magnesium; Or when we consume crops like sukuma wiki (kale) and nduma (arrow roots) which have been grown by the beds of rivers in urban areas, rivers which are heavily contaminated by human and animal sewage and contain dangerous chemicals and heavy metals.
The above challenges can be mitigated if the various regulatory agencies ensure that farmers adhere to proper crop and animal production norms, that crops are not grown along rivers contaminated with sewage, that waste from farms that use pesticides does not find its way into rivers, that animals are not grazed in urban areas, and that the disposal of drug inputs, urban waste, and medical waste is properly carried out.
The agencies in Kenya that are responsible for licensing, evaluating, setting and enforcing safe levels of residues which are allowed to remain in food for human consumption and the environment include the Department of Public Health, the Kenya Veterinary Board, the Pest Control Products Board, the Pharmacy and Poisons Board, the Directorate of Veterinary Services, the Kenya Plant Health Inspection Service, the Department of Fisheries, the Kenya Medical Practitioners and Dentists Board, and the National Environmental Management Agency.
These agencies should ensure that risk analysis of residues in food is regularly, appropriately and adequately carried out as is required by local and international standard-setting bodies to enable consumers to have safe food. This may entail ensuring drug inputs registered for uses in Kenya are safe. It may also entail ensuring the maintenance of a high-standard field surveillance, sampling, laboratory system, and meat inspection program which offers an effective detection system for monitoring contaminants and protects consumers from eating foods which have dangerous levels of residues.
- World Health Organization. 2002. Use of antimicrobials outside human medicine and resultant antimicrobial resistance in humans. www.who.int/mediacentre/factsheets/fs268/en/. Accessed November 14, 2008.
- Smith DL, Dushoff J, and Morris JG. 2005. Agricultural antibiotics and human health. PLoS Medicine 2(8):e232.
- L. M. Crawford. The impact of residues on animal food products and human health. Rev. sci. tech. Off. int. Epiz., 1985, 4 (4), 669-685.