Pesticide Pollution: A Replicable Environmental Disaster?

Pesticides are chemical compounds used to eliminate insects, rodents, fungi, and weeds. They include insecticides (insects), herbicides (weeds), fungicides (fungi), nematicides, molluscicides, rodenticides, plant growth regulators, and other compounds. Pesticides are classified based on a variety of variables, including their mode of entry, chemical makeup, and the target they kill. The World Health Organization (WHO) and Globally Harmonized System (GHS) classified pesticides based on their toxicity or harmful effects, prioritizing public health.

Pesticides are either natural or chemically synthesized compounds that are used to control a variety of pests

Pesticides are compounds used to control pests below damaging thresholds. They can be either natural or chemically synthesized. Natural pesticides are derived from compounds that occur in nature, such as diatomaceous earth and biological control agents. On the other hand, synthetic pesticides are compounds produced by people through industrial processes. Both types of pesticides are used in sectors like food, forestry, agriculture, and aquaculture.

Conventional pesticides, typically used in conventional agriculture, are synthetic and do not include biopesticides or antimicrobial pesticides. An example of a conventional pesticide is dichloro-diphenyl trichloroethane (DDT), introduced by Paul Herman Muller in 1939. Before the introduction of DDT, salty water and chemical compounds (organic and inorganic) were widely used to control pest populations.

Biopesticides, meanwhile, are derived from natural materials such as plants, animals, bacteria, or certain minerals. They can be further categorized into biochemical, microbial, and plant-incorporated protectants. Biochemical pesticides, for instance, control pests by using non-toxic mechanisms like pheromones that interfere with insect mating.

The use of pesticides has been associated with adverse effects on the environment and human health. Pesticide sprays can contaminate the air, soil, and non-target plants, with pesticide drift occurring during every application, even from ground equipment. Exposure to pesticides has been linked to health issues such as airway diseases (e.g., allergic rhinitis, asthma), hormonal imbalances, reduced immunity, and cancer.

Pesticides are classified based on a variety of variables, including the mode of entry, chemical makeup, and the target it kills

Pesticides are substances used to control pests such as insects, weeds, fungi, and more. They are classified based on various factors, including the mode of entry, chemical makeup, and the target it kills.

Mode of Entry

The mode of entry refers to how a pesticide reaches its target pest. For example, contact insecticides act by direct contact with the pest, while systemic pesticides move inside the plant, travelling through the xylem or phloem.

Chemical Makeup

Pesticides can be categorised as synthetic or natural. Synthetic pesticides are further classified as organic (structure-based) or inorganic. Examples of organic synthetic pesticides include organochlorines, organophosphates, carbamates, and pyrethroids. On the other hand, natural pesticides include pyrethrin, neem, spinosad, and rotenone.

The chemical structure of pesticides can also be used to classify them. For instance, organochlorines include DDT and aldrin, while organophosphates include chlorpyrifos and diazinon.

Target it Kills

Pesticides can also be classified based on their target organism. Some common classifications include:

• Insecticides: These target insects.
• Herbicides: These control weeds and grasses.
• Fungicides: These kill fungi.
• Rodenticides: These are used to kill rodents such as rats.
• Avicides: These control the population of birds.

The amount of pesticides used and exposure period are the two most important factors for pesticide toxicity

The toxicity of pesticides depends on the amount used and the exposure period. The World Health Organization (WHO) classifies pesticides based on their toxicity or harmful effects, with acute toxicity referring to a pesticide's toxicity to animals, plants, and humans following a definite short-term exposure. Acute toxicity is measured as acute oral, acute dermal, and acute inhalation toxicity. Chronic toxicity refers to harmful effects produced by long-term exposure to pesticides.

Pesticides can contaminate soil, water, turf, and other vegetation

Soil Contamination

Pesticides can contaminate the soil and harm the beneficial microorganisms that live in it. For example, pesticides can reduce the populations of bacteria and fungi that help with the process of nitrogen fixation, where atmospheric nitrogen is transformed into nitrates that plants can use.

Water Contamination

Pesticides can reach water bodies through runoff from treated plants and soil. Pesticide contamination of groundwater is a pressing issue, as groundwater is used for drinking water by about 50% of the US population. Pesticides can reach water-bearing aquifers from applications on crop fields, seepage of contaminated surface water, accidental spills and leaks, improper disposal, and injection of waste material into wells.

Turf and Vegetation Contamination

Pesticide sprays can directly hit non-target vegetation, or drift or volatilize from the treated area and contaminate the air, soil, and non-target plants. Drift occurs during every application, even from ground equipment. As much as 80-90% of an applied pesticide can be volatilized within a few days of application.

Pesticides can have both acute and chronic health effects, depending on the quantity and the ways in which a person is exposed

Pesticides are used to protect crops against insects, weeds, fungi, and other pests. They are either natural or chemically synthesized compounds used in sectors like food, forestry, agriculture, and aquaculture. While they are beneficial for food production, pesticides are potentially toxic to humans and can have both acute and chronic health effects. The impact on human health depends on the quantity of the pesticide and the way a person is exposed. Pesticide sprays can directly or indirectly contaminate the air, soil, and non-target plants, and studies have found pesticide residues in the air.

Acute toxicity can occur if a person is exposed to a high dose of pesticides through inhalation, ingestion, or contact with the skin or eyes. Short-term health effects include skin and eye irritation, respiratory issues, nausea, vomiting, vertigo, and headaches. In extreme cases, pesticide exposure can lead to acute intoxication and even poisoning, which may result in death. According to a WHO and United Nations Environment Programme (UNEP) report, worldwide, three million people are poisoned and 200,000 die due to pesticide exposure annually, with the majority of cases occurring in developing countries.

Prolonged or recurrent exposure to pesticides, on the other hand, can lead to chronic toxicity and long-term health effects. Pesticides can cause the production of reactive oxygen species, leading to oxidative stress and impacting cellular signaling pathways. Chronic health issues associated with pesticide exposure include various types of cancer, Alzheimer's disease, Parkinson's disease, neurotoxicity, infertility, leukemia, and diabetes. Additionally, pesticides can disrupt the endocrine system, mimic or antagonize natural hormones, and cause reproductive problems.

Farm workers, pest control workers, agricultural industry workers, and individuals residing near agricultural areas or exposed to household pesticides are at a particularly high risk of developing health issues due to pesticide exposure. The use of personal protective equipment (PPE) and proper handling and application of pesticides are crucial to minimize health risks.

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