Pesticides are either substances that deters, incapacitates or kills unwanted pests. Although the commercial use of chemical pesticides have increase only in the last 70 - 80 years, the use of pesticides can be traced back thousands of years! The ancient Sumerians used sulfur to protect their crops whereas the ancient Romans used oil, ash, sulfur and other minerals to protect themselves and their crops from various pests. The use of pesticides have led to significant gains in agricultural production by improving productivity and disease transmission. They also have positively impacted farmers' livelihoods through greater incomes.
So, if they are so beneficial to us, why all the negative press? Read on to find out more!
1. Types of pesticides
Pesticides, both biodegradable (pesticides which can be broken down ) and persistent (pesticides which linger in the environment for for months or even years), cover a wide range of compounds and are grouped by the types of pests they kill or deter. Insecticides deter insects, Herbicides control weeds or plant pests and Biopesticides (which are pesticides that are derived from natural materials such as animals, plants and bacteria) that may be used to control both insects and weeds or plant pests. There are also pest specific pesticides such as Fungicides which prevent fungus growth, Rodenticides kill rodents such as rats and mice and Slimicides which kill slime producing microorganisms such as algae and slime molds.
2. Effects of pesticide use
If the credits of pesticides include enhanced economic potential in terms of increased food production, then the debits have resulted in serious health implications to man and his environment. Pesticides have been linked with human health hazards for both the users of pesticides (high risk groups exposed to pesticides like production workers, formulators, sprayers, mixers, loaders and agricultural farm workers) and the general public (consumers). Pesticide exposure can cause a variety of adverse health effects, ranging from simple irritation of the skin and eyes, headaches and nausea to more severe effects such as affecting the nervous system, mimicking hormones causing reproductive problems, causing cancer and in some severe cases, even death!
In addition to killing insects or weeds, pesticides can be toxic to a host of other organisms including birds, fish, beneficial insects, and non-target plants. Insecticides are generally the most acutely toxic class of pesticides, but herbicides can also pose risks to non-target organisms. These chemical compounds could pollute the tissues of virtually every life form on the earth, the air, the lakes and the oceans, the fishes that live in them and the birds that feed on the fishes. Pesticide run-offs make their way into our ground water and pollutes it. Even the food we eat contains high amounts of pesticides. Pesticides that evaporate into the atmosphere can be carried thousands of kilometers by the wind, condenses and are poured back to the ground by rain. These chemicals, originally intended to stave off pests in agriculture, will then affect other flora and fauna, destroying natural ecosystems thousands of miles away from the intended area. The use of pesticides degrades soil as it decreases the general biodiversity of living organisms found in soil. Although some pesticides break down quickly when applied in soils, there are those which persist for longer periods. If we lose both bacteria and fungi, then the soil degrades. The effects on the soil organisms are similar to a human overusing antibiotics. Indiscriminate use may work for a few years, but after awhile, there aren't enough beneficial organisms to hold onto the nutrients.
Pesticides are often considered a quick, easy, and inexpensive solution for controlling weeds and insect pests in urban landscapes. No segment of the population is completely protected against exposure to pesticides and the potentially serious health effects. However, pesticide use comes at a significant cost. Pesticides have contaminated almost every part of our environment and its residues are found in soil and air, and in surface and ground water across the globe. Pesticide contamination poses significant risks to the environment and non-target organisms ranging from beneficial soil microorganisms, to insects, plants, fish, and birds.
3. Alternatives to pesticides
It is not all doom and gloom for the future as alternatives to pesticides are available. Some alternatives include methods of cultivation (polyculture, crop rotation and trap crops), use of biological pest controls (such as pheromones and microbial pesticides), genetic engineering, and methods of interfering with insect breeding which are becoming increasingly popular and often safer than traditional chemical pesticides. Release of other organisms that fight the pest is another example of an alternative to pesticide use. These organisms can include natural predators or parasites of the pests. Biological pesticides based on entomopathogenic fungi, bacteria and viruses cause disease in the pest species can also be used.
Some evidence shows that alternatives to pesticides can be as equally effective as the use of chemicals. That's good news for our health and the environment which we share with the myriad creatures which are living in it!
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