Pesticides are substances or a mixture of substances whose main aim is to destroy, repel, prevent or inhibit the action of any pest. A pest is any form of an insect, plant pathogens, weeds, birds, mollusks, nematodes (worms), and microbes that destroy human foods while in the field, during transportation or in stores. In addition, a pest can destroy other human properties apart from food or help spread harmful diseases. Pesticides are classified into five categories: a chemical substance, a biological agent, disinfectant, antimicrobial and a device. Since pesticides find use in both our homes and in farms, they have the potential of causing harmful effects to people and the environment. Chemically processed pesticides are the most harmful to humans. Most pesticides are designed to cause harm of kill pests. However, some pests have similar systems with that of human beings hence; they can harm and kill people. People are fortunate because they have the ability of avoiding such harms by following safety precautions written on every pesticide carrier (Govindarajan, 2012).
On the other hand, pesticides are classified in the following types (Types of Pesticides, n.d):
- Fungicides: meant for controlling fungi and oomycetes
- Bactericides: used to control bacteria
- Insecticides: for control of insects classified into Ovicides (for killing insect eggs), Larvicides (killing larva) or Adulticides (for killing mature insects)
- Miticides: used to control mites
- Rodenticides: control rodents
- Molluscicides control snails and slugs
- Virucides: control viruses
Pesticides and harm/ effects on people and environment
People who use pesticide try as much as possible to limit the area of effect, but it becomes impossible. Irrespective of the amount and area applied, pesticides spread in the air, get absorbed in the soil, or dissolve in water and spreads to wider areas than expected. Moreover, pesticides seep into the ground water that is consumed by human beings, poisoning people over a long time. In addition, residual pesticides found on plants are consumed by animals and even people causing serious illnesses like cancer, or even causing deaths. The research by United States (US) Geological Survey discovered that pesticides pollute almost every lake, stream and river in the US. All other places globally that use pesticides also expect similar results once a research is conducted (2011).
Farmers throughout the world use pesticides to safeguard their crops, but they also end up being affected by the same chemicals. Pesticides attack mechanisms by which pests or other targeted organism live and this means that human exposure to pesticide also has some harmful effects. The extent at which pesticides affect people and environment differentiates one pesticide from another. Some have minimal and negligible effects while others have adverse effects that require emergency medical attention. In the US and other places where chemical are used, their effects are classified into attack mechanism and toxicity (Withgott & Brennan, 2011). Harm of pesticides to people vary from short-lived to chronic, minor to serious and in some cases fatal cases are communicated. People face such harms because of they lack proper and safe application methods that result into skin contact, inhalation or ingestion of pesticides.
On the other hand, pesticides affect the environment where they are used. The environment consists of several substances and living things not intended to be affected by these chemicals making up pesticides. The concept of biodiversity forms the center to the effect of pesticides on environment. According to Goldstein (2011), biodiversity signifies the variation of life forms within a specified ecosystem, or the entire earth. Biodiversity measure the health of biological systems. An environment is termed healthier depending on the number of organism living within it, the higher the number the healthier the environment. Human beings too depend on nature for food water and many other essential things in life. With all these in mind, pesticides applied in the environment that houses many living and non-living organisms have the potential of causing a lot of harms to the biodiversity.
Exposure to pesticides
Pesticide exposure occurs when a pesticide contacts a surface or an organism. In people, pesticide exposure refers to getting pesticides on the body or inside the body. The harm effect of pesticide exposure to humans depends on the amount of pesticide involved and the duration of exposure. Pesticides contact human body through the following four main ways:
- Oral exposure: occurs when a pesticide is swallowed
- Inhalation-exposure through breathing in a chemical
- Dermal: contact through the skin, and
- Ocular: occurs through eyes
The above pesticide exposure ways are caused by one or a combination of the following methods. Oral exposure occurs when a chemical user fails to wash his or her hands before eating, smoking, or drinking after using a pesticide. Sometimes, farmers put pesticides in containers that initially stored food making people confuse chemicals with food, accidentally applying chemicals to food or splashing pesticides into the mouth are other causes of oral exposure to pesticides. Pesticide exposure is best avoided through getting rid of situations and practices where exposure occurs commonly. The second method is the inhalation, which occurs due to prolonged contact with chemicals in a closed or poorly ventilated area. Moreover, a person may breathe vapors from fumigants and other toxic pesticides. The following situation occurs when a person uses pesticides in areas close to people or applies fumigants without proper protective clothing. In other circumstances, people handling pesticides allow others to use a fumigated room too soon leading to inhalation of sprayed chemicals causing serious harms (Bellinger, 1996).
Dermal exposure is caused by failure to wash one’s hands after using a pesticide, its container. Dermal exposure also occurs when a person sprays pesticides on unprotected skin, wearing of chemical contaminated cloths and applying chemicals in a windy weather without proper positioning. Wearing clothing that provides inadequate protection, and touching pesticide-sprayed areas also cause dermal exposure. Finally, eyes exposure occurs because of splashing and spraying chemicals in the eyes. Farmers who apply chemicals during windy weather while facing the direction where the wind is coming from without eyes protection also suffer from ocular exposure. In addition, ocular exposure occurs as a result of rubbing eyes or the forehead with contaminated fingers and pouring dust, powder or granule chemicals without eye protections (Bellinger, 1996; 122-124).
The ability of a chemical to cause harmful effect is referred to as toxicity. Toxicity of a chemical depends on the amount and type of active ingredients and its formulation. In pesticides, the toxicity is determined by subjecting laboratory animals such as rats and rabbits to different chemical dosages of active ingredients and formulation materials over a specified period. These experiments assist in estimating the risk associated with a particular pesticide once exposure to human body. Different people react differently to pesticides exposure due to their differences in sensitivity. Before using a pesticide, it is advisable for an individual to know his or her sensitivity level to avoid harms associated with these chemicals. Chemical toxicity is divided into two kinds (Pesticide Safety Education Program (PSEP), 2012).
Acute toxicity refers to the level of poisonous a chemical is after a short-term exposure to humans. Acute toxicity describes effects that occur within 24 hours of chemical exposure. Chemicals that have high acute toxicity are dangerous and poisonous irrespective of the amount contacted. In addition, acute toxicity works as the basis for the warning statements on a pesticide’s label. The second type is the chronic toxicity that refers to a delayed poisonous effect from exposure to harmful pesticides. The following type concerns the general public and those working directly with these chemicals because of the potential exposure they are subjected to. Chronic toxicity is measured after three months of continuous or occasional exposure (Pesticide Safety Education Program (PSEP), 2012).
Harmful effects of pesticides to people
Pesticides course three major types of harms to people. Acute, delayed, and allergic.
These are injuries or illnesses that occur immediately a person is exposed to a pesticide, usually within 24 hours. The toxicity of pesticides is compared by determining their ability to cause acute effects. Acute effects are easier to measure and are also easily diagnosed as opposed to effects that take long to appear. If appropriate medical attention is taken, acute effects can be reversed. Four types of acute effects are caused by pesticides. These are the acute oral effect, the acute inhalation effect, the acute skin effect and the acute eye effect. In acute oral effects, the victim feels a severe burning in the mouth, throat and stomach. Other pesticides cause a burning in the digestive system while others are absorbed in the blood stream causing harms in different ways. For some pesticides, swallowing a small amount can cause an acute effect making it hard for a person to eat or drink.
Acute inhalation effects cause a burn to the entire respiratory system due to inhalation of some pesticides. The following effects make it difficult for a person to breath. Other chemicals inhaled may not have an effect on the respiratory system but enters the blood stream and cause serious harms. On the other hand, the acute dermal effects harm an individual’s skin. Once in contact with the skin, pesticides make the skin to itch, might cause blisters, cracks, or even result into color change. Other chemicals pass through the skin into the body systems and cause significant harms. Finally, acute eye effects occur when a pesticide gets inside person’s eyes and cause temporary or permanent blindness. In addition, such chemicals cause severe irritation in the eyes while others pass through the eyes into the body systems and introduce dangerous harms.
These are injuries or harms caused by pesticide exposure that take more than 24 hours to be recognized. Delayed effects are caused by repeated exposure to a pesticide or a group of pesticides over a long period. On the other hand, delayed effects result from a single exposure to a pesticide or many pesticides causing a harmful reaction that fails to be recognized until later. A person exposed to more than one type of a pesticide may get ill even if any one of these pesticides might be having no harmful health impacts. Moreover, a single exposure to a chemical might end up affecting the person after some time. For instant, increased exposure to paraquat herbicide causes fatal lung injuries that show up 3 to 14 days after the initial day of exposure. After a body is exposed to this chemical, it slowly builds up in the lungs destroying their cells.
Delayed effects also are triggered by some set of circumstances. Some chemicals show their effects after a short time but are delayed by a continuous exposure to different types of chemicals. A continuous and frequent exposure to chemicals leads into some factors getting into action making chemical reactions visible. For example, some genetic changes that occur in cancer development fall under this category. Delayed pesticide effects falls under three categories. Chronic effects, developmental and reproductive effects, and systematic effects.
Chronic effects are classes of illnesses that appear after a long time after a person is exposed to pesticides. Examples of chronic effects suspected to result from delayed pesticide effects include production of tumors (oncogenic effect), production of malignancy, and changes in genes/chromosomes. The time delay between the exposure and the time the effects are observed may cause unseen effects to the affected person. Sometimes many types of exposure might have occurred long time ago but becomes hard to identify. Laboratory animals are used to determine whether the effect will be similar to human beings through a series of tests. These tests are meant to determine delayed effects of pesticides. Once the pesticide research centers realize the pesticide has the capability of causing any type of delayed effect listed above, necessary steps are taken to reduce or eliminate such risks (Pesticide Safety Education Program (PSEP), 2012). Example of precautions taken to reduce or minimize delayed pesticide effects include:
- Eliminating the pesticide
- Labeling a pesticide with a clear and visible warning statement giving the possible effects
- People are required to wear specific personal protective equipments while handling such chemicals
- Changes in dosage and modes of application and waiting times before a crop is harvested for consumption, or slaughter in case of animals and grazing.
Some people develop certain harmful effects once they come into contact with substances that do not cause the same reaction to others. Such reactions are referred to allergy. Allergic reactions do not necessarily occur on the first time a person comes into contact with a substance, but sometimes they appear immediately a person is exposed to an allergic material. Once a person comes into contact with an allergic substance, for instance a pesticide, the body reacts by developing repelling response chemicals to that particular pesticide. Allergic response occurs later in the body a process called sensitization. Substances that cause a person to become allergic to them are called sensitizers (Pesticide Safety Education Program (PSEP), 2012).
Certain chemicals cause people to become allergic to them. For example, Poison Ivy may cause severe skin rashes in most people. There are different types of allergic effects caused by pesticides in humans. Once a person is exposed to such allergic chemicals, he or she develops a severe allergy-like response when exposed again later. Common allergic effects include:
- Systematic effects like asthma or life threatening shock
- Skin irritation like blisters, skin rashes and open sores
- Eye and nose irritation like itching, watery eyes and sneezing respectively
Because pesticides manufacturers cannot actually tell which pesticide will be allergic to a certain person, they usually manufacture pesticides with warning labels to caution users of temporary allergic side effect and the possible signs. Such safety precaution measures are essential in order to minimize cases of delayed effects caused by pesticides on humans.
Harms of pesticides to the environment
The environment consists of different substances and organisms both living and dead. Pesticides themselves are applied directly into the environment and have the capability of causing severe damages to the flora and fauna. When a pesticide is applied on a farm, it spreads to the soil, air, groundwater and surface waters and gets carried away from the farm. The physical and chemical characteristics of individual chemicals determine their transportation mode from the point of application to the environment. Most pesticide manufacturers never consider the immediate environment where a pesticide will be applied. Many forms of pesticide cause harm to the untargeted organism killing them all. In addition, pesticides were meant to kill insects, worms, but many other insects, animals and birds feed on these pests ingesting the same chemical substance that killed pests and affecting these animals and birds. The critical part is that these animals and birds help farmers in controlling pests but the farmer ends up killing both the pests and their prey. Research shows that for every targeted animal poisoned, approximately 300 non-targeted animals die (Govindarajan, 2012; 14).
Insects, soil and water based animals are examples of non-targeted casualties of pesticides. When it comes to the earth, insects like butterflies and bees suffer from pesticide usage even though they are not the main target. Moreover, birds feed on poisoned pests on the ground extending the effects towards them and causing a number to die. On the other hand, pesticides kill soil microbes and other animals that live in soil that play a great role in fixing nitrogen and other essential substances in the soil necessary for natural cycles. The effect inhibits the ability of soil to regenerate and remain viable for animal and plant life. An environment devastated by pesticides may take long to recover or never recover at all. The ministry of agriculture comes up with different forms of pesticides to eradicate pests that feed on farmers’ crops without having a second thought on the effects of these chemicals to non-targeted casualties such as birds (Bengtsson, AhnstrÖM & Weibull, 2005).
A research conducted in 1999 researchers from Environment Canada investigated the number of lawn pesticides in water samples collected from two rivers (Humber and Don Rivers) in Toronto. A comparison of the results collected within a period of four years indicated that there was a consistent pattern of pesticide residuals in tested waters. Waters from urban areas contained some amount of lawn care pesticides and the concentration increases after rainfall. In some tests, the level of chemical measured in urban ponds and streams exceeded government set levels needed to protect the aquatic life. Generally, an insufficient data is available that can enable us estimate the impact of pesticides use in the surrounding environment in terms of harming flora and fauna and the overall biodiversity (Environment Canada, 2011).
As seen from the following example, pesticides create a big impact to the environment ranging from destroying soil microorganism, animals, plants and aquatic life. Intensive pesticide and other crop protection materials have contributed to the decline in biodiversity over the last years. A survey conducted in Europe covering eight West and East European countries came up with alarming evidence of negative impacts of agricultural intensification on wild plant, animal and bird species. The researchers argued that even if the European policy to barn pesticide usage in the country, people still continue using them to control pests leading to disastrous consequences in the environment. The biological control potential is also reduced by pesticides used to control insects in Europe. Researchers came up with concluding remarks that for the country to restore its biodiversity, it must campaign for a wide shift towards farming using low volumes of pesticides over large areas (Geiger et al, 2010).
Health and environmental impact of pesticides
The most common health effects associated with pesticide exposure on humans are the reproductive effects and neurological effects. In addition, certain cancers are associated with pesticide exposure to humans and their environment. Below is an exploration of these two health effects of pesticide exposure to humans and the environment.
Direct exposure to chemicals used to manufacture pesticides results into elevated risks of reproductive or developmental effects. A number of women who work in pesticide manufacturing firms suffer from fertility problems and increased risks of unplanned abortions and miscarriage. For example, women working in Ontario farm have recorded increased cases of miscarriage that are believed to result from exposure to glyphosate and phenoxy acid herbicides. In addition, higher rates of premature births and miscarriage were seen when these women handled certain pesticides like organophosphates, three months before conception (Environment Health Sciences, 2009).
On the other hand, maternal exposure to pesticides especially those used for treating lawn gardens increases risks of certain birth effects like palate and cleft lip and defects found in limbs. A study conducted in Denmark on women working in a garden showed that their boys had moderate higher risks of undescended testes. In periods of high insect infestation women record more cases of birth defects, premature births and miscarriage because of high rates of pesticide use. Such periods include rainy seasons or during droughts (Associated Press, n.d).
There are several pesticides associated with central and peripheral nervous system effects on humans. Exposed workers in pesticide manufacturing and farms where these chemical are used suffer from sensory, mental, motor, and psychological effects. The most common pesticide associated with these effects is the neurotoxic like organophosphates, fungicides and some carbonates. In addition, exposure to pesticides lead to neurodegenerative disorders, like the Parkinson’s disease (PD), found in people occasionally exposed to pesticides mostly farmers. A specific suspected genetic suffers from PD because it affects people with similar genes (Horrigan, Lawrence & Walker, 2012; 461-463).
On the other hand, neurological effects occur in children who are exposed to chemicals in one way or they are born of parents working in pesticide contaminated places. A chemical like DDT has shown extended effects because of either its low-level or long-term exposure. The pesticide has faced a ban in Canada for many years because it affected a group of children from one agricultural community in Mexico. The tests done on these children revealed that they recorded poor stamina, low motor coordination and frequent memory loss (Horrigan, Lawrence & Walker, 2012; 500-502).
Signs and symptoms of harmful pesticide effects
According to Bellinger, (1996), pesticide effects occur in two categories, symptoms and signs. Symptoms are feelings that only the victim can notice and they include headache and nausea. Signs are clues recognized by the victim and others and include vomiting or fainting. The signs and symptoms of pesticide poisoning are similar to signs and symptoms of other illnesses. When a person who has been working with pesticides develops any of these complications, it is advisable to seek medical help from a qualified person or rush to the nearest healthcare center. Common examples of pesticide poisoning injuries include the following.
External irritation: The symptoms include redness, rashes, blisters on skin, burns on skin, swelling, burning inside eyes, nose, throat and mouth.
Pesticide poisoning: The causes nausea, diarrhea, vomiting, stomach cramps, headache, dizziness, weakness, confusion, excessive sweating, chest pains and difficulty in breathing. In addition, a person feels cramps and aches in all body muscles and pain all over the body. Conclusion
Irrespective of any type of exposure a person fall under, it is important to seek medical help to minimize risks associated with pesticide poisoning. Reducing or avoiding exposure of pesticides to our bodies reduces the harms they cause to people’s health. One of the most important ways of avoiding exposure is through using safety systems such as safety clothes or any appropriate personal protective equipment. In addition, chemical spread into many areas due to contact with the soil, water or air. Such contacts accelerate the rate of pesticide exposure to people and environment and ends up increasing its toxicity. On the other hand, pesticide manufacturers should consider our environment in order to come up with environment friendly chemicals that can save non-targeted plants and animals in the biodiversity.
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