Pesticides in the Environment


Pesticide Transport and Fate

Monitoring in the Environment

Methods for Measuring Human Exposure to the Agent

Exposure Pathways

Strategies for Preventing and Controlling Pesticides

Harmful Effects of Alachlor

Dose Response of Alachlor

Absorption, Distribution and Metabolism

Sites of Toxicity

Biomarkers of Disease and Molecular Mechanisms of Action

Risk Assessment

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Strategies for Preventing and Controlling Pesticides

Beginning in the 1940’s chemical pesticides emerged as a miracle enabling the control and prevention of pests in agriculture and household settings. However, it soon became evident of the devastating environmental and health harms that these toxic chemicals can cause. Furthermore, there are more concerns regarding the use of these chemicals. First off, as pesticides are recurrently applied, insect populations develop resistances to the chemicals. Also, the target pest’s natural predators are frequently killed off when pesticides are used. Additionally, as one pest species is eradicated, its competition may soon take its place.

Strategies Being Developed to Reduce Pesticide Reliance

Today Integrated Pest Management (IPM) plans are being widely adopted. IPM coordinates practices that lessen the need for pesticide applications. The target of IPM is to eliminate problems before they arise. IPM brings together the understanding of pests’ life cycles and their environmental interactions. The plans incorporate approaches that reduce hazards to people and the environment into the most economical manner feasible. The prevention plans combine approaches such as biological control and habitat modification. Only if inspection shows that there is still a problem at hand, are pesticides then applied.

General Goals of Integrated Pest Management (IPM) Plans

Reduce pesticide levels in the environment
Lessen hazards to people and the environment
Increase the use of natural pest controls
Develop a greater understanding of effective pest control methods
Establish programs that will encourage voluntary participation

Steps to Achieving Successful IPM Plans

Formulate Action Thresholds: Prior to taking action to control pests, thresholds should be identified that determine levels at which pests become an actual threat to the environment.

Identification and Proper Monitoring: Proper identification of pests is a must since not all of the organisms present may be creating the problem. Many of the organisms present may actually be beneficial in maintaining a balance in the insect community. An example of this is apparent in the aphid-praying mantis relationship. Aiming to rid your garden completely of aphids may cause you further troubles by disrupting the food supply of the beneficial mantises. Accurate and continual monitoring will ensure that pesticide applications are necessary and that the correct pesticide is used, enabling you to target certain pests while reducing the harm to others.

Prevention: The ultimate goal of IMP is to stop the problem before it starts. This is where responsibilities as a homeowner or agriculturalist come into play. Habitat modification may be required to decrease the levels of favorable habitats for target pests. In homes this may require changes such as eliminating points of entry by repairing screens, sealing all food sources, and vacuuming furniture. In agricultural settings prevention may be achieved by carrying out crop rotation, planting pest-resistant crops and pest-free rootstock. Many pests thrive primarily on one plant species. Large concentrations of single plant species are ideal pest breeding grounds. Plants will also maintain higher levels of natural defenses against pests if environmental conditions such as moisture and sunlight levels are favorable for that plant species. Proper spacing and early morning watering will help improve health and prevent the establishment of fungi populations.

Evaluation: Once the preceding steps have been taken and there is shown to still be a problem proper action should then be taken. Control methods which are the least harmful to the environment should be taken first. The use of natural controls is one option. If it has been determined that healthy predator populations are not present in agricultural settings they should be replenished. Natural predators such as lady beetles, mantises, spiders, and parasitic wasps can be purchased for these purposes. Another option is the use of pheromones which disturb the natural mating cycles of the pests. Sometimes trapping methods can also be employed. If further evaluation shows that the problem is still present pesticides can then be used. Target pesticides should be used before non-specific pesticides. Biopesticides are often more favorable than conventional pesticides. They are generally less toxic and are target specific versus conventional pesticides which harm other organisms ranging from insects to humans. Biopesticides can often be applied in smaller doses and decompose faster than conventional pesticides. This can lower toxic exposure levels and decrease environmental degradation and pollution.

Limiting Your Exposure to Toxins

There are instances when the application of pesticides is gong to be the chosen route of dealing with the problem. Understanding the toxicity of pesticides is important for reducing your exposure risk. Toxicity levels in pesticides are determined by chemical levels necessary to kill 50% of test populations. The EPA ranks pesticides into the following groups: highly toxic, moderately toxic, slightly toxic, and relatively toxic. They are labeled with the words danger and warning for the two most toxic levels respectively, and with the word caution for the lesser two categories. Limit hazardous exposure by using less toxic pesticides. Pesticides are labeled for their intended use including the target pest. Another rule of thumb is to apply pesticides when there is the least amount of wind if applicable. If you apply it in windy conditions it may not only spread in areas where it is not needed, but it may also be absorbed into clothing or skin if not properly covered.

Preventing Exposure When Applying Pesticides

It is important to properly protect yourself from direct exposure to pesticides during application. The necessary protection equipment may very depending on the protective needs which are provided on the pesticide labels. Protective equipment includes the following:

Chemical Goggles: It is important to use chemical goggles rather than general safety goggles. Chemical goggles include a baffled airway which inhibits splashes from entering the inside of the goggles.
Gloves: Unlined, full-length plastic or rubber gloves should be used. If gloves are lined residue can become trapped in the lining and is hard to remove. It is also important to cuff the gloves back to drips from getting inside.
Coveralls or Apron: The material used should prevent splashes or spills from being absorbed through the cloth. Studies have also been found to show that pesticides absorption levels around the trunk of the body are higher than other areas such as the arm.
Hat: The absorption rate of pesticides is also very high on the scalp and forehead. Plastic caps are recommended as they are waterproof and prevent absorption.
Boots: Rubber overshoes are suggested since they prevent absorption and are easy to clean.
Ear Protection: Ear plugs prevent pesticide exposure via the ear canal.
Respirator: Remember to replace cartridges in cartridge respirators to keep them functioning properly.

Use and Cleaning of Equipment

All protective equipment should be used only for protection from pesticides. Do not wear equipment such as raingear for general purposes. The equipment should also be thoroughly cleaned with soap and water after every use. It is also smart to follow other preventative measures such as cleaning/changing personal clothing at least daily. Do not bring clothing that has been exposed to pesticides into the house.

Guide to Responsible Use and Storage of Pesticides

Do not store pesticides in unlocked cabinets that are within the reach of children. Pesticides are extremely toxic to children.
Be aware of products stored in bathrooms and kitchens. Common household pesticides often found in these areas include disinfectants, mildew removers, bleach insect sprays and repellents, and flea shampoos.
Read all labels and warnings before using pesticide products.
When applying pesticides keep children, pets, and toys out of the area at least as long as the label advises.
Do not transfer pesticides into containers that could be associated as something else such as food.
Do not apply insect repellents over cuts, irritated skin, eyes, mouth, hands, or directly over the face.
Teach children about the dangers of poisonous materials.
Do not store unnecessary amounts of pesticides. Purchase only what you need at that time.
Consider all people and animals with access to the application site.
Apply an appropriate level of caution to those who might come into contact and become exposed.
Look for pesticide alternatives.

Other Useful Websites

Introduction to Understanding Integrated Pest Management Plans

Protecting Children in Schools from Pesticides

Guide to Specific Pests and Effective Habitat Modification

Controlling Pests Around Your Home. California Department of Pesticide Regulation.

Biological Control and Home Gardening

Key Pest Photographs