Pesticides are substances which are made to kill pests. A pest can be insect, weed, bacteria, fungus, rodent, fish or any other troublesome organism. Many pesticides can also pose risks to people.
This has been a subject of many debates these last couple of years! However, in many cases the amount of pesticide people are likely to be exposed to is too small to pose a risk. To determine risk, person must consider both, the toxicity or hazard of the pesticide and the likelihood of exposure. Many scientists believe that the rise in hormonally driven cancers, such as cancer of the breast and prostate, may be due to the ability of many synthetic chemicals to act as endocrine disrupters, and particularly to the ability of synthetic chemicals to imitate estrogen. Alarmed by the potential of these chemicals to harm the developing nervous systems of infants and children, environmental groups have called for a ban on many of them. What of this is really true?
Globally, some 2.5 million tons of pesticides are applied every year and most of it is targeted at agricultural cultures. Approximately 250 basic chemicals made by more than 50 companies are registered for use as pesticides in food and feed production in the United States. More than a quarter of a million U.S. children aged 1–5 ingest a combination of 20 different pesticides every day. More than 1 million preschoolers eat at least 15 pesticides on a given day. Overall, 20 million children aged 5 and under eat an average of 8 pesticides every day. Pesticide use has increased 50-fold since 1950, and 2.5 million tons of industrial pesticides are now used each year.
Some 610,000 children aged 1–5 consume a dose of neurotoxic organophosphate insecticides that the government deems unsafe. More than half of these unsafe exposures are from one pesticide—methyl parathion.
What are pesticides exactly?
Pesticide is a broad term, covering a range of products that are used to control pests. A pesticide may be a chemical substance or biological agent, such as a virus or bacteria. The most common pesticides that you may use in your everyday life are
- slug pellets,
- ant powder,
- weed killers, and
- Rat and mouse baits.
Other pesticides you may have heard of include:
- Algicides -control algae in lakes, canals, swimming pools, water tanks, and other sites.
- Antifouling agents - kill or repel organisms that attach to underwater surfaces
- Antimicrobials - kill microorganisms (such as bacteria and viruses).
- Attractants – kills the attract pests
- Biopesticides – these are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and certain minerals.
- Biocides - kill microorganisms.
- Disinfectants and sanitizers - Kill or inactivate disease-producing microorganisms on inanimate objects.
- Fungicides - kill fungi (including blights, mildews, molds, and rusts).
- Fumigants - produce gas or vapor intended to destroy pests in buildings or soil.
- Herbicides - kill weeds and other plants that grow where they are not wanted.
- Insecticides - kill insects and other arthropods.
- Miticides - kill mites that feed on plants and animals.
- Microbial pesticides - microorganisms that kill, inhibit, or out compete pests, including insects or other microorganisms.
- Molluscicides - kill snails and slugs.
- Nematicides - kill nematodes (microscopic, worm-like organisms that feed on plant roots).
- Ovicides - kill eggs of insects and mites.
- Pheromones - biochemicals used to disrupt the mating behavior of insects.
- Repellents - repel pests, including insects (such as mosquitoes) and birds.
- Rodenticides - control mice and other rodents.
- plant growth regulators,
- Bird and animal repellents…
Do we really need pesticides?
Today's modern agriculture produces plenty of food and all at a reasonable price. Most of us take it for granted that we can buy whatever food we want, whenever we want. All this couldn’t be possible without the use of pesticides! Pests every year compete with humans for food, destroy property, spread disease or are a nuisance. That’s why, there is no chance that the use of pesticides could be stopped. Over the last 60 years farmers and growers have changed the way they produce food in order to meet the expectations of consumers, because they want the product during the whole year!
Farmers use pesticides to:
- protect crops from insect pests, weeds and fungal diseases while they are growing
- prevent rats, mice, flies and other insects from contaminating foods whilst they are being stored
- safeguard human health, by stopping food crops being contaminated by fungi
But, all the consumers must know that as pesticides are used to kill unwanted pests, weeds and molds, they can also harm people, wildlife and the environment. Pesticides form a very wide and complex subject which includes issues such as food, human health and safety, the effects on wildlife and the environment, as well as the European interests.
Chemical structure of pesticides
The main categories of chemical pesticides are
- chlorinated hydrocarbons, such as DDT and dieldrin;
- organophosphates, such as parathion; carbamates, such as carbaryl and aldicarb; and
- Inorganic pesticides made from basic elements, such as copper, lead, arsenic, and mercury.
Many people don’t know this fact but, organophosphates, the most common group in use today, work by interfering with the normal transmission of nerve impulses. Although they do not persist in the environment –they belong to the class of highly toxic pesticides. Some of them are actually used as nerve agents during World War II.
In generally, all pesticides could be divided into two big groups!
- Chemical pesticides
Most common chemical pesticides are:
- Organophosphate Pesticides
These pesticides affect the nervous system by disrupting the enzyme that regulates acetylcholine, a neurotransmitter. Most organophosphates are insecticides.
- Carbamate Pesticides
These pesticides are made to affect the nervous system by disrupting an enzyme that regulates acetylcholine, a neurotransmitter.
- Organochlorine Insecticides
These pesticides were commonly used in the past, but many have been removed from the market due to their health and environmental effects
- Pyrethroid Pesticides
These were developed as a synthetic version of the naturally occurring pesticide pyrethrin, which is found in chrysanthemums. Some synthetic pyrethroids are toxic to the nervous system.
Most common bio-pesticides are:
- Microbial pesticides consist of a microorganism as the active ingredient. These microorganisms could be bacteria, fungus…etc. Microbial pesticides can control many different kinds of pests.
- Plant-Incorporated-Protectants (PIPs) - these are pesticides that plants produce from genetic material that has been added to the plant. The protein and its genetic material, but not the plant itself, are regulated by EPA.
- Biochemical pesticides are naturally occurring substances that control pests by non-toxic mechanisms. These include substances, such as insect sex pheromones, that interfere with mating, as well as various scented plant extracts that attract insect pests to traps.
Health effects of pesticides
A major consideration in approving pesticides for use is whether they pose an unreasonable risk to humans. The fact is that pesticides can cause harm to humans, animals, or the environment because they are designed to kill or otherwise adversely affect living organisms. The fact is that pesticides can present danger to consumers, bystanders, or workers during manufacture, transport, or during and after use. They don’t represent a threat only to the human, but to pets and whole environment!
Although many people don’t know thins, but the fact is that many fruits and vegetables such as apples, celery, cherries, grapes, nectarines, peaches, pears, peppers, potatoes, red raspberries, spinach and strawberries, may contain pesticide residues after being washed or peeled.
Risk of exposure to pesticide applicators, or other workers in the field after pesticide application, may also be significant and is regulated as part of the pesticide registration process. Besides human health risks, pesticides also pose dangers to the environment.
Important thing to know is that none of these pesticides is 100% effective. When sprayed with pesticides, many pests will initially be very susceptible, but- not all pests are killed, and some with slight variations in their genetic make-up are resistant and therefore survive. Pest resistance to a pesticide is commonly managed through pesticide rotation or tank mixing with other pesticides.
Regulation of pesticides
In most countries of the world- if you want to order, sell or use a pesticide you must have approval from a government agency. Some pesticides are considered too hazardous for sale to the general public and are designated restricted use pesticides. During the registration process, a label is created which contains directions for the proper use of the material. Based on acute toxicity, pesticides are assigned to a Toxicity Class. The law requires the EPA to reexamine the allowable levels of hundreds of pesticides on individual crops and ultimately come up with about 9700 new application-level determinations. The FQPA mandates that pesticides be screened both as carcinogens and as endocrine disrupters. Big problem is that pesticides misuse is illegal in most countries.