Pesticides are chemical compositions that have saved millions of human and animal lives since the beginning of their use. They are employed to eradicate fungal, animal, and insect pests that damage crops and carry vector-borne diseases. They have played a key role in the revolution of the agricultural industry results in an increase in food production, saves time and energy consumption, and a reduction in costs.
Although pesticides provide substantial benefits, they have huge damaging impacts on the natural environment and human health.
Nearly 95% of pesticides are used in farms and reach other organisms apart from the targeted pests. Some factors like breeze, humidity, and temperature contribute to the spread of pesticides in the air and water surfaces. More than 26 million people suffer from pesticide poisoning with nearly 20,000 deaths a year.
Major Ecological Effects of Pesticides
Pesticides are involved in a wide range of organic micropollutants. They have two specific mechanisms of contamination with negative consequences which are biomagnification and bioconcentration.
Biomagnification or biological magnification refers to a process within the food chain where living organisms that have tolerance regarding a certain toxin within their system get eaten by living organisms higher in the foodchain. The level of the chemicals within the living organisms would rise gradually leading to disease, impairment, and in extreme cases death.
The main receptor for many insecticides like DDT is fat tissue. Therefore, these pesticides accumulate in fat. They are “lipophilic” and transmit into an organism from the surrounding medium. They are fat-soluble in human adipose tissues when consuming contaminated edible fish.
Metabolism Process of Pesticides, Their Degradation in Water and Soil
Two major biological mechanisms cause pesticides degradation:
1- Microbiological reactions in water and soil
2- Pesticide metabolism within organisms consumed as part of their absorption of food
The degradation process in soil called mineralization includes chemical reactions such as photolysis and hydrolysis which breaks pesticides down into smaller compounds such as NH3, H2O, and CO2. Some chemicals, for example [2,4-dichlorophenoxyacetic acid], degrade fairly quickly in the soil, while others degrade less easily [2,4,5-trichlorophenoxyacetic acid]. Other chemical compounds are very persistent and do not degrade gradually like atrazine.
UV photolysis, microbial degradation, hydrolysis, or chemical oxidation are the way of pesticide degradation in water. There are some treatments to reduce pesticide contamination such as activated carbon absorption techniques, chlorine, UV photolysis, and ozone treatment.
Fatal Effects of Pesticides on the Environment
- Aquatic Creatures
Water surfaces are contaminated by pesticides due to different factors like wind or temperature. When they reach bodies of water, they are absorbed or ingested by aquatic creatures like fish and lead to organ failure, disease, and eventually death. Moreover, these chemicals alter the water’s pH levels, so the normal function of aquatic life gets interfered with. Chemical pollutants reduce the amount of oxygen in the water which can result in mental and behavioral alterations in the fish populace or suffocate them.
- Ozone Layer
Chemicals in pesticides contribute to the production of tropospheric ozone as the farmers do not utilize a shield zone around the crops. When pesticides are sprayed on fields to disinfect soil get absorbed in the air and soil that produce volatile organic compounds they tend to react with other chemicals and create a pollutant known as tropospheric ozone.
Pesticides applied in the form of powder can spread in the air and reach other regions. The more the wind blows, the more these chemicals spread. They can also stick to dust particles in the air and get inhaled which can cause poisoning or disease.
- Micro-Organisms in the Soil
Micro-organisms have a vital role in breaking down organic substances and helping better crop growth. Pesticides percolate into the soil in the long run and lead to the termination of micro-organisms. It takes a lot of years for micro-organisms to be able to live in that soil once more.
Fatal Effects on Human Health
As mentioned earlier, pesticides tend to preside in the environment. They are found in the air, water, or even our foods. They can result in serious inevitable consequences through consumption, breathing, or contact with the skin.
– Acute Health Effects
Pesticides can cause short-term adverse effects on human health that can be acute or lead to immediate health issues like:
- Coughing, sore throat, and irritation in the respiratory tract.
- Irritation of the eyes and skin.
- Feelings of nausea, queasiness, and diarrhea
- Losing consciousness and headaches
- Feeling extremely weak, convulsions and/or demise
- skin burning, stinging, and itching
- rashes and blisters
– Chronic Health Effects
Pesticides can also cause long-term adverse health issues that can even become chronic in nature, and these may not show any observable symptoms for weeks, months, or even years after exposure:
- cancer and other tumors
- nervous system damage
- infertility and other reproductive problems
- damage to the liver, kidneys, lungs, and other body organs
- leukemia, lymphoma, and cancers of the brain, breasts, prostate, testes, and ovaries birth defects, stillbirth, spontaneous abortion, sterility, and infertility
- Parkinson’s ailment
- depression and anxiety
Health Effects of Certain Classes of Pesticides
Organophosphates & Carbamates:
These pesticides function similarly to nerve gas: they attack the brain and nervous system, interfering with nerve signal transmission. Symptoms include headaches, nausea, dizziness, vomiting, chest pain, diarrhea, muscle pain, and confusion. In severe poisoning incidents, symptoms can include convulsions, difficulty breathing, involuntary urination, coma, and death.
Symptoms of fumigant exposure include irritation of skin, eyes, and lungs, and extremely irritating to eyes and lungs. Dichloropropene, metam sodium, and metam potassium are all cancer-causing chemicals and metam sodium causes reproductive harm.
These insecticides are synthetic chemicals that are structurally similar to botanical compounds but have been designed to be more persistent. Symptoms of pyrethroid poisoning include tremors, salivation, headache, fatigue, vomiting, stinging and itching skin, and involuntary twitching.