Pesticides boon or bane?

The caption of this article was a discussion question I set for my final year students in my course in Pest Management about 30 years ago. Little did I think that one day I would have to ask the whole nation this same question or ask the nation to debate on it. Indeed, it is now time our nation to take a critical look at pesticides use.

Anyway, the question divided the class into two groups as reflected by the structure of the caption of this article. One group which found the question difficult considered it as the bane of their lives, as pesticides indeed are to man if not judiciously used. The students in this category since they left the University have nicknamed me, “Pesticides: Boon or Bane? Discuss”. However, the students who found the question manageable considered it as a boon (Koko) in their life, as pesticides, indeed are, if, judiciously used. Ghana would have indeed been among the second category of students, from the way pesticides are loosely used in the country as if they are not dangerous. Yes, indeed, they are.

Our Attitude to Pesticide Use

From our bedrooms to in and around our homes, pesticides, such as insecticides, rodenticides and herbicides are applied frequently to control mosquitoes, mice and weeds, respectively. On our farms and in our gardens fungicides, insecticides and herbicides are being frequently applied to ensure good quality and high yields. Herbicides have virtually replaced human labour which is not only very expensive but also scarce and not dependable. It is amazing to see people comfortably sitting in areas sprayed with sweet scented insecticides or being fumigated with smoke from coils, as if an air – freshener has been used. Sadly, they are innocently killing themselves silently and slowly!! However, the generous pungent smell of a pesticide serves as a warning for people to keep off from the danger of sprayed areas at home in particular, for at least between twnety to 30 minutes.

Many of our farmers have different perceptions about pesticides;

some think pesticides are harmful only to pests and are harmless to man, many have the notion that pesticides sprayed on vegetables cannot be detected many believe that small doses of pesticides on the skin have no effect on the body no matter the number of times of exposure. Hence their attitude towards pesticides have been

*No need to wear protective clothing during pesticide application.

*One can stop spraying and eat or drink and then go back to continue spraying.

*Not necessary to always wash yourself and clothing after pesticide application.

*Not necessary to observe preharvest interval for pesticides.

*Vegetables can be washed to remove pesticides sprayed on them.

*It is okay to use pesticide containers as drinking cups, for storing salt and cooking oil after washing them.

The essence of writing this article is to draw the attention of fellow countrymen to the dangers of the indiscriminate use of pesticides as it is happening now in our dear motherland. Ghana is not for us alone. The country is for generations yet unborn and so there is the urgent need for the judicious use of pesticides both in health and agriculture in order to preserve our environment for healthy living and for posterity.

Pesticides: What Are They?

According to the National Institute of Environmental Health Science (2022) a pesticide is any substance used to kill, repel and control certain forms of plant and animal life that are considered as pests. Pests are animals and plants which harm us and cause damage to our crops. In our fight against them to protect our health and crops, we have resorted to the use of various pesticides which are toxic compounds and can kill both man and pests. The only difference is that the concentrations of pesticides that can kill pests are lower than those fatal to man, so that they can be safely handled and applied. However, repeated exposure to the low concentrations makes them harmful to man.

Pesticide is the general term given to all the toxic compounds developed for the control of both medical and agricultural pests. However, the various toxic compounds developed for the control of a specific type of pest have been named to reflect the target pest.

For instance, the specific pesticides for the control of insects, fungi, mice, nematodes, and weeds are termed insecticides, fungicides, rodenticides, nematicides and weedicides, respectively.

Pesticide Formulation
On the market we buy pesticides in various forms. The various forms are not in their pure technical state which are very dangerous to handle. The technical products for the market, are prepared into forms termed formulations which are safe to handle and apply because they contain the right concentrations of active ingredients, which are effective against pests. Some of the formulations on our market are sprays, dust, granules, smoke coil, and wax blocks. Pesticides being formulated for safe handling and application does not mean that they should be handled without great care.

Pesticide Poisoning
Even though the various pesticides we use contain low concentrations of their active ingredients meant to kill our pests, our repeated exposure to them can lead to a buildup of their concentrations in man. The vital functions pesticides disrupt in pests leading to their death are the same as those of man. These vital functions in living organisms are the nervous, digestive, circulatory, respiratory and reproductive systems. Some pesticides have some carcinogenic effect on man.

We are being poisoned either gradually or suddenly when pesticides enter our body through the mouth, nostril and skin. The ability of a pesticide to harm us through the mouth is referred as its oral toxicity. This is the adverse effects occurring in the body after an oral intake of a single dose of a substance, or multiple doses taken in within 24 hours (National Research Council, 1977). A single dose of a pesticide taken in orally rarely kills except in the case of exposure to class A pesticides, which are very lethal, or someone who intentionally wants to commit suicide. However, we are taking multiple doses of pesticides as we eat our vegetables and fruits. As farmers spray the crops for high and good quality yield, some pesticide residues are left on the produce they harvest for the market. These residues are not harmful if farmers observe the pre-harvest intervals of the pesticides they use. The preharvest interval of a pesticide is the period one needs to observe before a produce is harvested after pesticide application. This is to allow residues of the active ingredient (a. i.) to breakdown before the produce is harvested. After the given interval, pesticide residues on produce are not harmful, because their active ingredients break down, except for pesticide with zero tolerance limits. The residues of such pesticides should not be found at all on produce harvested for the market.

For vegetables like okro, their economic parts have shorter maturity periods than the pre – harvest intervals of most of our vegetable pesticides and so the chances of residues remaining on harvested produce are high. For instance, the economic maturity period of the okro fruit, for most cultivars is between 3 and 4 days. However, most of our vegetable pesticides have pre-harvest interval of between 2 and 3 weeks. It is therefore advisable that such vegetables and fruits bought from farms, shops and market places should first thoroughly be washed with water and rinsed in salt water or vinegar solution to reduce the amount of pesticide residue before being consumed.

We are also poisoned through the nostrils and skin because as we are spraying, we breathe in some of the spray and some land on our skin especially the face. The degree of poisoning depends on how long we are exposed to the pesticide. For sprays, the total concentrations whether inhaled or deposited on our skin have been measured. Acute inhalation toxicity is the total adverse effects caused by a substance following a single interrupted exposure by inhalation over a short period of time e.g., 24 hours or less, to the substance capable of being inhaled. For poisoning through the skin, acute dermal toxicity, it is the adverse effects occurring within a short time of dermal application of a single dose of a substance (National Research Council 1977). Such extreme occurrence of pesticide in the air and on our body hardly occurs unless it is a planned suicide, or always staying in sprayed areas as if they have not been sprayed.

As we frequently expose our bodies to sprayed pesticide, the seemingly harmless substance gets into our system through the nostrils and skin. The fat – soluble ones get accumulated in our fats and marrows until they get to acute levels. It is when we are depending on our fats and marrow during old age or recovering from a serious sickness, that pesticides are released from the fatty tissues and marrow into our system and that is when their effect is felt.

Environmental Impact
Apart from our health being affected our environment is affected by the indiscriminate use of pesticides which tend to affect our wildlife. There are some wildlife and crops which were very prevalent before the widespread use of pesticides but are now scarce or extinct. Bees which are very sensitive to some insecticides appear to be scarce of late. Snails and earthworms which tend to appear after rainfalls are scarce these days and snails, to some extent have become a delicacy for the rich!!

In the Ashanti Akyem and Akyem areas, snails appeared in abundance during the rainy season and people used lanterns to pick them from the bush and along roads. In Ashanti Akyem excess snails were shelled and the fresh snails were stringed on long sticks and dried as a means of preservation. The stringed snails which were popularly referred to as Bompata “Walking Stick” are sadly no more!!

The scarcity of snails on the market now could probably be attributed to the widespread use of gramoxone – based herbicides in the country, for weed control. An experience in my backyard garden supports this observation. Before I started using gramoxone – based herbicide (Knock-down) to control weeds in cassava plots, I used to collect snails after rains in Cape Coast.

The possibility of the gramoxone based herbicide influencing the population of snails and earthworms is high, since gramoxone – based herbicides tend to be absorbed by the clay and humus components of the soil which are parts of the food chains of snails (FAO, 1986) and earthworms (Lee, 1985). The chances of these soil creatures being eliminated by clay and humus particles contaminated by these types of herbicides is high.

The scarcity of cocoyam on the market could also be attributed to herbicides or their residual effects. Some herbicides can remain in the soil for some time after they have effectively cleared target weeds. It is most likely that cocoyam is sensitive to the herbicides being widely used in cocoyam growing areas.

The prevalence of mosquitoes in Ghana in spite of the frequent spraying of the insecticides and regular use of mosquito coils should tell us that mosquitoes are far from being effectively managed by the use of various insecticides on our market now. It is possible that the current breed of mosquitoes in Ghana have developed insecticide resistance. If this my observation is true, then we have serious malaria problem ahead of us, because the more we continue to use mosquito sprays, the tougher the mosquito would become. Even trying to control them physically is not easy. It is clear that the mosquitoes prevailing now have changed in behaviour. They have learnt to sit on your door and lead you into your room as you open your door. Physically they appear to be springy and so if you find one sitting on the wall you have to hit very hard to be able to kill it. Otherwise, when you lift your hand from the wall, it would spring up and fly away.

One thing interesting about current breed of mosquitoes is that, it appears they have studied our pattern of sleep. They wait when we are deep asleep, then they come singing into our ears. You wake up and slap yourself and they take cover. In about 10 to 15 minutes time, they come and sing again into your ears. If you miss it the second time, they would keep on repeating their song until you manage to sleep and they draw their blood or you keep vigil!! They have learnt to pass under doors and through spaces between the door and the door frame to ensure they keep you company throughout the night. The apparent disappearance of vulture from our environment should indeed be a cause of worry. Vultures being scavengers are very much attracted to dead animals. It is possible that vultures feeding on rodenticide poisoned mice carelessly thrown outside could be a cause of their decreased population, in addition to other factors such as the felling of very tall trees, like Ceiba for timber, which served as safe ecological niche for laying their eggs.

National Pesticide Policy

The above observations appear personal but are National in nature. They are common knowledge but they appear to be taken for granted because changes in nature are gradual and initially appear harmless. The changes in the populations of our wild lives should be considered seriously before we observe changes in man as a result of the current widespread use of pesticide in Ghana. In the light of these observed changes the National Pesticide Policy should be reviewed in the direction of the proper handling and use of pesticide in Ghana. A Pesticide Board should be established and mandated to evaluate, legislate and supervise the marketing of pesticide in Ghana.

The board should have research institutes across the country study the environmental impact of the various pesticides being used in the various parts of the country. Currently we need to know the extent to which herbicides used by house owners and farmers is influencing cocoyam cultivation and the populations of snails, earthworms, toads and frogs in the environment.

There is also the need to know the link between the use of rodenticides and the disappearing of vultures in Ghana. A very serious study should be carried out on the influence of the various mosquito sprays and coil on the behaviour and population of mosquitoes in Ghana.

The board should have an educational unit to prepare teaching materials on the proper use of pesticides for sellers and hawkers of pesticides. The hawkers of pesticides in the market places need to be trained so that they would be in a better position to explain the proper use of pesticides to the public instead going from place to place playing jingles they have recorded to the hearing of all. Yℇ aya nnuro papa afiri China.

Ekum mmoa ahodoↄ pii
Ntℇfrℇ, nkura, ntontom, ntatea, mmoa a ℇwↄ fie nyinaa.

Yℇde bi nso gu agyananbea a ℇkum mmoa a ℇwↄ hↄ nyinaa.

Nkura aduro o o, yℇde nkuraduro aba oo!!
Yℇwↄ nnuro a ℇkum nkakarika.
These jingles only emphasize the killing power of pesticides but not how they can possibly harm man and therefore, they should be applied with great care. Sadly, these hawkers and pesticides shop keepers are not aware that they should protect themselves and once a while, go for a medical check-up.

As you can infer from this article, pesticides are neither bane nor boon. They are like a double-edged sword; they are both boon and bane depending on their judicious use. In the interest of our survival and for posterity, we all have to learn to apply pesticides with great caution to avoid the occurrence of a Silent Ghana in the future, like the occurrence of Silent Spring in the USA (Rachel 1972) as a result of the widespread use of organochlorine pesticides which killed most birds in the spring, when bird lovers were waiting to hear birds sing but there was only silence. This led to the ban on the use of organochlorines for the first time in the USA. I hope we are not expecting such a situation to occur in Ghana as a result of our unstructured use of pesticides, before we take action.

Only a strong policy and good public education on pesticide use can save both the present and future Ghanaians from pesticide poisoning. This is a clarion call!! Oh Lord, save us from a Silent motherland – Ghana.

References
FAO (1986), Farming snails. Food and Agriculture Organization of the United Nations. Rome.

Lee, K.E. (1985), Earthworms: Their ecology and relationships with soils and land use. Academic Press Inc.

National Institute of Environmental Health (2022)

National Research Council (1977), Principles and procedures for evaluating the toxicity of household substances. A report. National Academy of sciences

Carson. R. (1972). Silent Spring. Houghton Mifflin Boston.

By Yaw Opoku Asiama

(Retired Lecturer, University of Cape Coast, Cape Coast)

(Tel. No.: 0332130506)