The Adverse Effects of Pesticide Usage in Agriculture

Pests are a familiar thorn in the side of farmers. These are living bodies, plants or animals, which are harmful to crops and they can range from insects and weeds to rodents and fungi. Pesticides are used to eliminate these external agents, and they can be insecticides, herbicides, fungicides, or molluscicides, amongst others.  

The Food and Agriculture Administration (FAO) defines them as substances or a mixture of substances that can be used for controlling, preventing, or destroying any pest or disease-causing vectors, undesirable plants, or animal species affecting food production, managing, selling, storage, or transportation. As the definition shows, they attack crops throughout the food value chain.  

The benefits of pesticides are clear and plentiful. They improve productivity by leaps and bounds in agriculture. Diseases such as blight, weeds, and insect pests like caterpillars attack crops from the field to the silo. Weeds compete with crops for soil nutrients and moisture, while insects feed on everything from leaves to grain. Eliminating these guarantee higher crop yields and reduce losses; as a result, humans have relied on them to do these for centuries: pyrethrum, a plant (chrysanthemum)-derived pesticide, has been in use for over 2000 years.  

The issues with pesticides are similar to those posed by fertilizers: they are a key agricultural input when applied responsibly, and extensive use of the synthetic forms can become toxic to both man and the environment. Synthetic pesticides are widely used in all forms of agriculture; the FAO estimated global usage of 2.7 million tonnes in 2020, averaging 1.8 kilograms per hectare. The chemical nature of pesticides, their high biological activity, and their tendency to persist in the environment may cause harmful effects both to humans and the environment.  

Harmful exposure to pesticides could be both occupational and secondary. Occupational exposure comes to farm workers or pesticide applicators. These people may be exposed through spills and splashes to the skin or inhalation through airways during application. The general population could be affected by exposure to pesticide residues on food or drinking water or the drift of airborne pesticides to residential areas close to farms.  

Some less costly pesticides such as dichlorodiphenyltrichloroethane, more commonly known as DDT, can remain for years in soil and water. Contact with or the ingestion of large quantities of these pesticides may lead to acute poisoning or even cancer mutations. It is for this reason that several countries agreed to the 2001 Stockholm Convention, an international treaty aimed at eliminating or restricting the use of persistent organic pollutants (POPs).  

The effect of this treaty can be seen in Europe, where the FAO reports that pesticide usage has increased by just 3 percent in the last two years, as the European Union has created further policy to monitor and control pesticide usage. Developing nations, however, continue to use many old, non-patented, environmentally persistent, and banned chemicals, as those are likely to be available and inexpensive. There is also little knowledge among smallholder farmers as to what pesticides they should or shouldn’t use, as they may not know the possible health and environmental implications. Thus, farmers do not take precautions to protect themselves during the administration of pesticides and, as one would expect, often buy the cheapest pesticides they can find. 

Research from the Small-scale Women Farmers Organization in Nigeria (SWOFON) and the Alliance for Action on Pesticide in Nigeria (AAPN), with support from the Heinrich Böll Foundation, has shown some active ingredients found in pesticides which are still in active use in Nigeria but are banned in other countries.  

Active ingredients such as Atrazine, Carbofuran, Cypermethrin, Mancozeb, Profenofos, and Triazophos are neither banned nor restricted in Nigeria. Atrazine, banned in the EU, United Kingdom, China, and Canada and highly restricted in the USA, is carcinogenic and has been found to affect the reproductive system, as well as causing birth defects in fetuses. Cypermethrin causes paraesthesia to the skin and can attack the gastrointestinal system. Exposure to Triazophos may produce a range of symptoms from muscle spasms to psychosis. It could also show respiratory damage with illnesses such as pulmonary oedema, dyspnoea, and respiratory paralysis.  

Some active ingredients are outlawed in the country. Butachlor, which is carcinogenic, mutagenic, and causes tumours is banned in Nigeria, as well as the EU, UK, and India, with its use being highly restricted in the USA. The highly-dangerous Endosulfan is also banned. Pesticides containing the ingredient are banned in over 80 countries from the EU to Australia and Brazil and a global ban on its production came into effect in 2012. The ingredient attacks the skin through rashes and skin irritation and is an endocrine disruptor which causes reproductive and developmental damage in humans, also being neurotoxic.  

In October 2022, the National Food and Drug Administration of Nigeria (NAFDAC) announced an immediate ban on Dichlorvos, a carcinogenic ingredient which also causes neurodevelopmental harm. In May 2023, (NAFDAC) has notified the public of an immediate ban on carbofuran and phase-out plans for some active ingredients including Ametryn, Thiamethoxam, Clothianidin, and Thiacloprid. 

NAFDAC announced future bans on Paraquat, Chlorpyrifos, and Atrazine with effective dates from 1st January 2024, 1st November 2024, and 1st January 2025, respectively. The regulatory body has also enforced stricter regulations on the production of agrochemicals such as Glyphosate. Before the actions from NAFDAC, the Federal Ministry of Agriculture and Rural Development (FMARD) had already instituted harsh measures on the usage of pesticides containing these ingredients. 

The solutions will have to be regulatory: the onus falls on NAFDAC, the major regulatory body, to ban or regulate the use of potentially harmful pesticides. Only the regulatory bodies have the cache to ban the importation or sale of these pesticides. NAFDAC has received notice from FMARD that the European Union and the United Kingdom are still exporting neonicotinoid pesticides to Nigeria. An example of such an ingredient is Imidacloprid, which happens to be banned in the EU. 

Hence, importation control is paramount, as Nigeria should not become the dumping ground for banned substances. There will also be the need for agricultural extension programmes, educating farmers on the dangers of excessive and irresponsible pesticide usage, how to use and administer pesticides, and what pesticides to avoid.