Occupation Health Issue Of Pesticides Biology Essay

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Pesticide is an important occupational health issue because pesticides are used in a large number of industries, which puts many different categories of workers at risk. Extensive use puts agricultural workers in particular at increased risk for pesticide illnesses. Workers in other industries are at risk for exposure as well. commercial availability of pesticides in stores puts retail workers at risk for exposure and illness when they handle pesticide products. The ubiquity of pesticides puts emergency responders such as fire-fighters and police officers at risk, because they are often the first responders to emergency events and may be unaware of the presence of a poisoning hazard. The process of aircraft disinsection, in which pesticides are used on inbound international flights for insect and disease control, can also make flight attendants sick.

Different job functions can lead to different levels of exposure. Most occupational exposures are caused by absorption through exposed skin such as the face, hands, forearms, neck, and chest. This exposure is sometimes enhanced by inhalation in settings including spraying operations in greenhouses and other closed environments, tractor cabs, and the operation of rotary fan mist sprayers.

INTRODUCTION

Any substance or mixture of substances intended for preventing, destroying or controlling any pest, including vectors of human or animal disease, unwanted species of plants or animals causing harm during or otherwise interfering with the production, processing, storage, transport or marketing of food, agricultural commodities, wood and wood products or animal feedstuffs, or substances which may be administered to animals for the control of insects, arachnids or other pests in or on their bodies. The term includes substances intended for use as a plant growth regulator, defoliant, desiccant or agent for thinning fruit or preventing the premature fall of fruit. Also used as substances applied to crops either before or after harvest to protect the commodity from deterioration during storage and transport.

A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling or mitigating any pest. A pesticide may be a chemical substance, biological agent , antimicrobial, disinfectant or device used against any pest. Pests include insects, plant pathogens, weeds, molluscs, birds, mammals, fish, nematodes and microbes that destroy property, spread disease or are a vector for disease or cause a nuisance. Although there are benefits to the use of pesticides, there are also drawbacks, such as potential toxicity to humans and other animals. According to the Stockholm Convention on Persistent Organic Pollutants, 10 of the 12 most dangerous and persistent organic chemicals are pesticides.

Many pesticides can be grouped into chemical families. Prominent insecticide families include organochlorines, organophosphates, and carbamates. Organochlorine hydrocarbons could be separated into dichlorodiphenylethanes, cyclodiene compounds, and other related compounds. They operate by disrupting the sodium/potassium balance of the nerve fiber, forcing the nerve to transmit continuously. Their toxicities vary greatly, but they have been phased out because of their persistence and potential to bioaccumulation. Organophosphate and carbamates largely replaced organochlorines. Both operate through inhibiting the enzyme acetyl cholinesterase, allowing acetylcholine to transfer nerve impulses indefinitely and causing a variety of symptoms such as weakness or paralysis. Organophosphates are quite toxic to vertebrates, and have in some cases been replaced by less toxic carbamates. Thiocarbamate and dithiocarbamates are subclasses of carbamates. Prominent families of herbicides include pheoxy and benzoic acid herbicides; triazines, ureas , and Chloroacetanilides. Phenoxy compounds tend to selectively kill broadleaved weeds rather than grasses. The phenoxy and benzoic acid herbicides function similar to plant growth hormones, and grow cells without normal cell division, crushing the plants nutrient transport system.

WHAT IS A PEST

Pests are living organisms that occur where they are not wanted or that cause damage to crops or humans or other animals.

Examples

insects,

mice and other animals,

unwanted plants

fungi,

microorganisms such as bacteria and viruses, and

prions.

WHAT IS A PESTICIDES

A pesticide is any substance or mixture of substances intended for:

preventing,

destroying,

repelling, or

mitigating any pest.

Though often misunderstood to refer only to insecticides, the term pesticide also applies to herbicides, fungicides, and various other substances used to control pests.

Under United States law, a pesticide is also any substance or mixture of substances intended for use as a plant regulator, defoliant, or desiccant.

CLASSIFICATION OF PESTICIDES AND ITS EFFECT

Chemical Pesticides

Some examples of chemically-related pesticides are

Organophosphate Pesticides - These pesticides affect the nervous system by disrupting the enzyme that regulates acetylcholine, a neurotransmitter. Most organophosphates are insecticides. They were developed during the early 19th century, but their effects on insects, which are similar to their effects on humans, were discovered in 1932. Some are very poisonous. However, they usually are not persistent in the environment.

Carbamate Pesticides affect the nervous system by disupting an enzyme that regulates acetylcholine, a neurotransmitter. The enzyme effects are usually reversible. There are several subgroups within the carbamates.

Organochlorine Insecticides were commonly used in the past, but many have been removed from the market due to their health and environmental effects and their persistence .

Pyrethroid Pesticides were developed as a synthetic version of the naturally occurring pesticide pyrethrin, which is found in chrysanthemums. They have been modified to increase their stability in the environment. Some synthetic pyrethroids are toxic to the nervous system.

Biopesticides

Biopesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals. For example, canola oil and baking soda have pesticidal applications and are considered biopesticides. At the end of 2001, there were approximately 195 registered biopesticide active ingredients and 780 products. Biopesticides fall into three major classes:

(1) Microbial pesticides consist of a microorganism as the active ingredient. Microbial pesticides can control many different kinds of pests, although each separate active ingredient is relatively specific for its target pest[s]. For example, there are fungi that control certain weeds, and other fungi that kill specific insects.

The most widely used microbial pesticides are subspecies and strains of Bacillus thuringiensis, or Bt. Each strain of this bacterium produces a different mix of proteins, and specifically kills one or a few related species of insect larvae. While some Bt's control moth larvae found on plants, other Bt's are specific for larvae of flies and mosquitoes. The target insect species are determined by whether the particular Bt produces a protein that can bind to a larval gut receptor, thereby causing the insect larvae to starve

(2) Plant-Incorporated-Protectants (PIPs) are pesticidal substances that plants produce from genetic material that has been added to the plant. For example, scientists can take the gene for the Bt pesticidal protein, and introduce the gene into the plant's own genetic material. Then the plant, instead of the Bt bacterium, manufactures the substance that destroys the pest.

(3) Biochemical pesticides are naturally occurring substances that control pests by non-toxic mechanisms. Conventional pesticides, by contrast, are generally synthetic materials that directly kill or inactivate the pest. Biochemical pesticides include substances, such as insect sex pheromones, that interfere with mating, as well as various scented plant extracts that attract insect pests to traps. Because it is sometimes difficult to determine whether a substance meets the criteria for classification as a biochemical pesticide,

Many commonly used pesticides are.

Algicides or algaecides for the control of algae

Avicides for the control of birds

Bactericides for the control of bacteria

Fungicides for the control of fungi and oomycetes

Herbicides  for the control of weeds

Insecticides , organophosphates, carbamates, and pyrethroids) for the control of insects - these can be ovicides, larvicides or adulticides

Miticides or acaricides for the control of mites

Molluscicides for the control of slugs and snails

Nematicides for the control of nematodes

Rodenticides for the control of rodents

Virucides for the control of viruses

PUBLIC HEALTH ISSUES AND PEST

Debilitating and deadly diseases that can be caused or spread by pests such as insects, rodents, and microbes pose a serious risk to public health.  Examples of significant public health problems that are caused by pests include:

Vector-Borne Diseases - Infectious diseases such as West Nile virus, Lyme disease, and rabies can be carried and spread by vector species such as mosquitoes, ticks, and rodents.  EPA registers several pesticide products, including repellents, that may be used to control the vectors that spread these diseases.

Asthma and Allergies - Indoor household pests such as cockroaches can contribute to asthma and allergies.  In addition to registering products to control these pests, EPA also provides information to the public about safely using these products in homes and schools.

Microbial Contamination - Various microorganisms, including bacteria, viruses, and protozoans, can cause microbial contamination in hospitals, public health clinics, and food processing facilities. EPA registers antimicrobial products intended to control these microorganisms and help prevent the spread of numerous diseases.

Avian Flu - HYPERLINK "http://www.epa.gov/pesticides/factsheets/avian.htm"Avian flu, sometimes called bird flu, is an infection that occurs naturally and chiefly in birds. Infections with these viruses can occur in humans, but the risk is generally low for most people. EPA works to register and make available antimicrobial pesticide products  that may be used to kill avian influenza virus on inanimate surfaces and to help prevent the spread of avian flu viruses.  These products are typically used by the poultry industry to disinfect their facilities.

Prions - Certain proteins found in cells of the central nervous system of humans and animals may exist in abnormal, infectious forms called "prions."  Prions share many characteristics of viruses, and may cause fatal diseases. 

Anthrax -Biological agents such as Bacillus anthracis spores can cause a threat to public health and national security.  EPA has issued emergency exemptions for several pesticides that were used in anthrax spore decontamination efforts, including (but not limited to): bleach, chlorine dioxide, ethylene oxide,hydrogen peroxide and peroxyacetic acid, methyl bromide, paraformaldehyde, and vaporized hydrogen peroxide. 

ALTERNATIVES OF PESTS

Alternatives to pesticides are available and include methods of cultivation, use of biological pest controls , genetic engineering, and methods of interfering with insect breeding. Application of composted yard waste has also been used as a way of controlling pests. These methods are becoming increasingly popular and often are safer than traditional chemical pesticides.

Cultivation practices include polyculture , crop rotation, planting crops in areas where the pests that damage them do not live, timing planting according to when pests will be least problematic, and use of trap crops that attract pests away from the real crop. 

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.[19] Biological pesticides based on entomopathogenic fungi, bacteria and viruses cause disease in the pest species can also be used.

Interfering with insects' reproduction can be accomplished by sterilizing males of the target species and releasing them, so that they mate with females but do not produce offspring. This technique was first used on the screwworm fly in 1958 and has since been used with the medfly, the tsetse fly, and the gypsy moth. However, this can be a costly, time consuming approach that only works on some types of insects.

Another alternative to pesticides is the thermal treatment of soil through steam. Soil steaming kills pest and increases soil health. citation needed.

In India, traditional pest control methods include using Panchakavya, the "mixture of five products." The method has recently experienced a resurgence in popularity due in part to use by the organic farming community.

ENVIRONMENTAL EFFECT OF PESTICIDES

Pesticide use raises a number of environmental concerns. Over 98% of sprayed insecticides and 95% of herbicides reach a destination other than their target species, including non-target species, air, water and soil. Pesticide drift occurs when pesticides suspended in the air as particles are carried by wind to other areas, potentially contaminating them. Pesticides are one of the causes of water pollution, and some pesticides are persistent organic pollutants and contribute to soil contamination.

In addition, pesticide use reduces biodiversity, reduces nitrogen fixation, contributes to pollinator decline, destroys habitat and threatensendangered species.

Pests can develop a resistance to the pesticide , necessitating a new pesticide. Alternatively a greater dose of the pesticide can be used to counteract the resistance, although this will cause a worsening of the ambient pollution problem.

APPLICATIONS OF PESTICIDES

Pesticides are used to control organisms considered harmful. For example, they are used to kill mosquitoes that can transmit potentially deadly diseases like west nile virus, yellow fever, and malaria. They can also kill bees, wasps or ants that can cause allergic reactions. Insecticides can protect animals from illnesses that can be caused by parasites such asfleas. Pesticides can prevent sickness in humans that could be caused by mouldy food or diseased produce. Herbicides can be used to clear roadside weeds, trees and brush. They can also kill invasive weeds that may cause environmental damage. Herbicides are commonly applied in ponds and lakes to control algae and plants such as water grasses that can interfere with activities like swimming and fishing and cause the water to look or smell unpleasant. Uncontrolled pests such as termites and mould can damage structures such as houses.] Pesticides are used in grocery stores and food storage facilities to manage rodents and insects that infest food such as grain.

Pesticides can save farmers' money by preventing crop losses to insects and other pests;., farmers get an estimated fourfold return on money they spend on pesticides.pesticides reduced crop yields by about 10%. 

Use of pesticides in household

Many household products are pesticides. All of these common products are considered pesticides:

Cockroach sprays and baits

Insect repellents for personal use.

Rat and other rodent poisons.

Flea and tick sprays, powders, and pet collars.

Kitchen, laundry, and bath disinfectants and sanitizers.

Products that kill mold and mildew.

Some lawn and garden products, such as weed killers.

Some swimming pool chemicals.

FUTURE ASPECTS

Pesticide safety education and pesticide applicator regulation are designed to protect the public from pesticide misuse, but do not eliminate all misuse. Reducing the use of pesticides and choosing less toxic pesticides may reduce risks placed on society and the environment from pesticide use. Integrated pest management, the use of multiple approaches to control pests, is becoming widespread and has been used with success in countries such as Indonesia, China, Bangladesh, the U.S., Australia, and Mexico. IPM attempts to recognize the more widespread impacts of an action on an ecosystem, so that natural balances are not upset. New pesticides are being developed, including biological and botanical derivatives and alternatives that are thought to reduce health and environmental risks. In addition, applicators are being encouraged to consider alternative controls and adopt methods that reduce the use of chemical pesticides.

Pesticides can be created that are targeted to a specific pest's life cycle, which can be environmentally more friendly. For example, potato cyst nematodes emerge from their protective cysts in response to a chemical excreted by potatoes; they feed on the potatoes and damage the crop. A similar chemical can be applied to fields early, before the potatoes are planted, causing the nematodes to emerge early and starve in the absence of potatoes.

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