Environmental Impact Of Pesticides
Pesticides can travel far from where they were originally applied. They drift in the wind when sprayed in gardens or can run off into streams and rivers when washed away by rainfall. In some cases the pesticides will remain there for years and go from one organism to another.
Selective pesticides are only dangerous to their targeted pests however non-selective pesticides are harmful to many organisms which are beneficial to the ecosystem. People who handle pesticides have to be careful with their application in order to reduce their damage to the surrounding environment. Incorrect use of pesticides leads to:
- Disruptions in the local ecosystem
- Long-term damage to soils and water sources
- Death or injury to non-targeted organisms
- Superbugs which grow resistant to the pesticide
Insecticides tend to be the class of pesticides that are the most harmful to the environment, followed closely by fungicides and herbicides. Their effect on the ecosystem depends on whether they are fat soluble or water soluble.
Water soluble pesticides seep into surrounding environment when they are carried along by stormwater. Fat soluble pesticides are carried along by animals which results in high levels of toxicity in the food chain.
Toxic Food Chains
Fat soluble pesticides such as DDT accumulate in the food chain and wreak havoc to every animal on it. The animals at the top of the food chain are likely to suffer from higher levels of toxicity due to a phenomenon known as bioaccumulation. Small levels of the pesticide will be found in insects such as grasshoppers which will be eaten by mice and shrews. The owl then eats the shrews and gains a level of toxicity that is equal to the sum of the toxicity levels of all of the animals at the bottom of the food chain.
The owls die off first thanks to bioaccumulation. The next animal down the food chain then enjoys a surge in numbers thanks to the low population of its natural predator and then decreases the population of the animal at the bottom.
The use of chlordecone in Guadeloupe and Martinique has resulted in an environmental disaster that affects many parts of the globe.
The two islands were great places to grow bananas. Farmers there used chlordecone to increase their yields however they found that they had to keep using higher and higher doses to reach the same levels of production. Chlordecone was banned in 1993 however the farmers continued to use it illegally, spraying their plantations from the sky all the way until 2002. The high concentration of chlordecone in those territories forced local authorities to close down banana plantations due to high levels of soil toxicity. Sources of drinking water were contaminated as well and estimates say that they are likely to stay that way for decades. Toxic levels in the area’s fish were the highest ever recorded.
Humans suffered as well. Those islands now have prostate cancer rates that are among the highest in the world.
Minimizing the Risk of Pesticides to the Environment
How deadly a pesticide is to its environment is based on how toxic the pesticide is and the level of exposure. Minimizing the exposure risk to the environment is the best way to keep it safe from toxic levels that cause damage to the ecosystem. Good ways for minimizing the risk are:
- Implementing Integrated Pest Management
- Choosing pesticides that are less toxic
- Using the correct dosage as stated on the label
- Ensuring that the pesticide is spread only over the target area
- Using equipment that is well-serviced and maintained properly
The parts of the environment that are most affected by toxic levels of pesticides are:
- The soil which tends to hold onto pesticides such a nematicides which change the chemical properties of the soil and make it inhospitable to future crops
- Water sources which is where water-soluble pesticides are washed into by rains
- Non-target species such as bees which we rely on for the pollination. The worldwide decline of honeybee colonies has been directly linked to heavy pesticide use.