Herbicides- Destroys or hinders the development of weeds.

Fungicides- Destroys or hinders the development of fungi.

Insecticides- Keeps insects away or destroys them.

Rodenticides- Prevents rodents from killing off plants and crops.

Growth Regulators- Prevents the excess growth of a plant.

Received from http://en.wikipedia.org/wiki/Pesticides Oct. 28, 2004.

Using Pesticides

Pesticides have caused a lot more problems than meets the eye, and have been for some time now.  Lately most of the pesticide spraying has been done to kill off the mosquitoes carrying the West Nile Virus.  Unfortunately, in Maricopa County one man's organic farm has been sprayed with pesticides without his knowing, and has been done multiple times.  On the good side of things, the county now has a schedule of when spraying will occur in The Arizona Republic, but uncertain whether you can prevent the spraying of your crops.  It's causing problems for many farmers who want to keep their crops organically grown and free from pesticide use.  They aren't sure if their sales will drop because of this or even how to wash the pesticide off.  According to County officials, the pesticide is a form of pyrethoids which is the safest and easily washes off and degrades in the sunlight (The Arizona Republic).  Others fear for their health, Mikel Crews and his father have had health problems ever since a "mist in the air" settled on them while they were working outside.  Apparently there was aerial spraying taking place on pines near their acreage and was carried by the wind onto their acreage.  As early as the next day, they reported respiratory problems and over the following years, their health declined.  Mikel's father died 3 years later from cancer and Mikel can no longer work due to his illness.  Although the doctor can't pinpoint a cause it's likely that it began with their first exposure and worsened after the second in 2003.  State Representative Joey Hensley co-sponsored a bill that created a 100 ft. no-spray zone around schools, churches and occupied dwellings.  This is similar to those bills in Alabama, Louisiana and North Carolina, but there is no law in Tennessee that requires a no-spray zone or that you be informed (The Tennessean).

On the up side, there are many people trying to "weed" out the use of pesticides.  One great example is the Portland Bureau of Parks and recreation set up an experimental pesticide-free program.  It will involve 6 different parks from around the area, 3 of them will be pesticide free and 3 will use organic pesticide alternatives which include vinegar and natural soap.  The program will run about 3 years and hopefully make a change in fighting with weeds in the city.  This program by any means is not cheap, costing $30,000.  The city of Portland is recognized by Salmon-Safe, being certified by minimal negative impact on the quality of water and fish habitat (The Oregonian).  This program (Salmon-Safe) works with farmers to make the ecological system safe and to protect surrounding waters.  Today over 30,000 acres have been certified by Salmon-Safe in the Northwest of the U.S. (www.salmonsafe.org/farms/index.cfm).  Portland was the first city to ban Polystyrene foam products and is the leader in recycling and using alternative forms of transportation.  This experiment is their beginning process to preserve the ecosystem and Salmon and to assess alternative pesticide management methods (The Oregonian). 

All information below was provided by: Raven, P.H. & Berg, L.R. 2001. Environment.

History

There are two main categories of pesticides, first generation and second generation.  First generation pesticides are those that have been used before the 1940's which contained both organic and inorganic compounds.  Second generation pesticides are those which came after the 1940's, and many of those are still used today.  Dichloro-diphenyl-trichloroethane (DDT) is an example of a second generation pesticide and was the first with insect killing abilities.  Chlorinated hydrocarbon is an organic compound that contains chlorine and is also a DDT.  The problem is that this substance degrades slowly in the environment and can linger for years after its use, causing much damage.  Much of their use was in the 40'-60's, they are now banned because of the harm the posed for the environment, humans and wildlife.

Of the first generation pesticides, there were two main pesticides used and they were either organic or inorganic.   The inorganic  pesticides contained lead, mercury and arsenic and were very toxic to pests.  Many of these are not used today because of their stability in the environment and lack of degradation, causing them to seep into soil and water over time and cause much damage to the ecosystem.  There are two different types of organic pesticides and they are all poisonous.  The first type, botanicals are plant-derived and insect killers, some examples include nicotine from tobacco and pyrethrin from chrysanthemum flowers  The second type, synthetic botanicals are man-made insecticides and are chemically modified from the natural botanicals.  For example pyrethroids are like pyrethrins but are much more toxic to fish and are toxic to mammals and bees. 

There were two types of pesticides, one used during World War II and the other used during the Vietnam War.   Organophosphates used during WWII, contained phosphorus and was an organic compound used in Germany as nerve gas.  This type of pesticide is comparable to the toxicity of arsenic and cyanide, some of the most toxic poisons and are very toxic to birds, bees and aquatic organisms.  Most of these have taken the place of chlorinated hydrocarbons for agricultural use, but are not widely available due to their high level toxins.  Herbicides caused many problems during the Vietnam War, they were being sprayed by the United States to expose hiding places and destroy crops by the Vietcong and North Vietnamese Troops.  Their impact is still being seen/felt today for example, ecologically many of the forests have been ruined, the health of Vietnamese people along with U.S. militants have been exposed to very toxic chemical called dioxins.  There have been birth defects in animals, serious illnesses in humans, and defects such as stillbirths, female reproductive disorders and certain cancers that increased in areas where herbicides were sprayed. 

Benefits

Disease Control

The many diseases insects carry and can transmit to humans, two examples include malaria  from Anopheles mosquitoes, and typhus from flies and lice.  Many pesticides including DDT have helped control these problems especially by killing off mosquitoes and decreasing the malaria problem.  Although DDT was harmful, it's use was continued after being discontinued in Sri Lanka because a rise of malaria, but has now been replaced by another, less toxic pesticide today.

Crop Protection

Approximately 1/3 of the worlds crops are eaten by pests and crop protection is a must with the growing population.  Pesticides take care of weeds, insects, animals, and plant pathogens (fungi and bacteria that cause disease) that have the ability to destroy the crops.  About 200 species have the power to do large damage to crops and cause major economical loss.  An example is the potato beetle in Colorado that will eat the leaves of potato crops, this hinders the plants ability to produce large tubers for harvest.  When crop loss happens, its done in mass quantities, this is due to farmers harvesting a crop over a large area (monoculture) with limited diversity in the ecosystem.  However, in wetlands, forests and other natural ecosystems there are diverse populations of predators, parasites and plant species and the destruction is nearly impossible.  In a monoculture, a pest/insect is going to thrive and produce, being able to kill off hundreds of plants at one time. 

Problems

Resistance

After so much use of a pesticide, a pest/insect can become resistant.  This is called genetic resistance, any inherited characteristic that lowers the effect of the pesticide use.  Over the 50 years of pesticide use, there are 520 species of insects and mites that have a genetic resistance to distinct pesticides.  Pests now have multiple resistances and there are 17 species that have built a resistance to ALL major insecticides allowed for legal use by farmers.  This obviously creates huge problems for farmers and their crops.  How can this occur?  When a pesticide is used, not all of the insects die, therefore they pass those genes to survive to their offspring.  This in turn causes evolution, any cumulative change in a population of organisms-as offspring produce a higher level of resistance is passed on.  One solution was to spray more of the pesticide or spray a more costly pesticide.  This resulted in the pesticide treadmill, the cost of applying pesticides increases, while their effectiveness decreases. 

Ecosystem

The most severe problem because they kill not only those intended but those not intended.  Many animals that feed off the plants, or are sprayed accidentally eventually die due to exposure.  This problem moves right up through the food chain and involves the issues with endangered species mentioned earlier.  It can also cause a massive increase in a pest problem that was not in existence before. For example, the lemon tree issue,  the use of DDT on lemon trees to control certain pests actually caused an outbreak of a scale insect (sucking insect that attacks plants) that wasn't a problem. 

Bioaccumulation/Bioconcentration

The build up of a persistent pesticide in a organisms body.  This is what happened with the Bald Eagle, Condor and Brown Pelican.  Their egg shells are too soft and can't withstand the incubation period.  When this pesticide level increases as it moves through the food chain, it is known as biological magnification. An example would be: plant → small fish → large fish → heron  and as it goes from each organism the level increases in concentration.

Mobility

Pesticides are moved so easily that it creates multiple problems. Aerial spraying, they can blow from one inorganic farm onto the crops of an organic farm causing the farmers a possible loss in crops and damage.  Also, falling onto humans when they are outside working as was the case with Mikel and his father, or falling onto animals/plants/organisms in the surrounding area killing them.  The Environmental Working Groups (EWG) found that 14.1 million U.S. residents were drinking water contaminated with 5 different herbicides. This finding brought about a study that stated 3.5 million people in the Midwest have an elevated cancer risk. 

Human Health

Risk of exposure is higher than we think.  Higher levels of a pesticide over a short period of time can damage the bodies organs and possibly lead to death, where as long term, low levels can lead to cancer.  Either way, exposure is not a good thing.  According the WHO approximately 3 million people are poisoned each year and of those 220,000 die due to pesticide exposure.  These chemicals can cause and increase breast and testicular cancer, birth defects, and a decrease in sperm count.  According to the EPA,  About 84% of homes in the U.S. have had some sort of pesticide product in their home.  For example, pest strops, bug bombs, flea Collars, pet shampoos, aerosols, liquids and dusts.

Solutions

Cultivation Methods

Instead of rows upon rows of the same plant, alternate the rows with different plants.  Knowing the right time to plant, fertilize and irrigate a crop will promote healthy plants that are better able to resist pests, because they don't have the factors of the environment.  Also try strip cutting, where you have one crop segment harvested at a time.  The unharvested area provides a habitat for natural predators and parasites of the pest species.

Biological Controls

Using naturally occurring organisms, parasites and predators to control the pests.  This relates to using one species to control another, but as we remember, this could cause problems with invasive species. 

Reproductive Controls

Sterilizing some members of the species.  The males are top choice because the species used for this sterilization process mate many times where as the females mate only once.  The only problem is that it would need to be kept up with on a regular basis.  

Pheromones/Hormones

Pheromones-sexual attractors.  Once the substance is known it can be replicated and traps can be used to capture and kill the pests and confuse them so they can't locate any mates.  Hormones-chemicals that regulate growth and metamorphosis.  Creating synthetic hormones to disrupt the life cycle of pests, leading to abnormalities and death.  Known as MIMIC and can have negative affects on beneficial insects.  

Genetic Controls

Using selective breeding, breeding plants in infected areas but are not destroyed with standard plants to create a pest-free plant. 

Irradiating Foods

Growing the food and then exposing it to ionized radiation, this kills salmonella and other microorganisms as well as bacterium causing food poisoning.  The FDA approved this process for fresh poultry, fruits and vegetables in 1986 and in 1992 the first irradiated foods were sold.  In 2000, the U.S.D.A approved irradiation for raw meats.

Laws

Food, Drug and Cosmetic Act (FDCA)-1938 found the need to regulate pesticides in foods but provided no means of regulation.  1954 they passed the Pesticide Chemicals Amendment or the Miller Amendment that required looking for acceptable and unacceptable levels of pesticides in foods.  In 1958 added the Delaney Clause which stated that any substance with the power to cause cancer were banned in processed food.  However, the Clause did not cover fruits, raw foods, vegetables, milk, fish and poultry.

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)-1974 regulated pesticide effectiveness and the prevention of buying pesticides that didn't work.  In 1988 a re-registration was done for the older pesticides to meet the standards of the new pesticides. 

Food Quality Protection Act-1996 amended the above two and revised the Delaney Clause.  This Act reduced the amount of time it once took to ban a pesticide from 10 years to 14 months.