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The use, storage, and disposal of pesticides in a variety of situations and what effect these chemicals have on our health and our environment is of major concern. Pesticides are utilized in urban areas, suburban areas, and rural areas. Each type of usage will be addressed.

Urban usage includes residential areas, public areas, commercial buildings, and industrial areas. In residential areas pesticides are applied by trained individuals as well as by citizens in and around homes. Each time the person is exposed to the pesticides in all the aforementioned settings, there is a potential for increased body burden of the chemical. Individuals can easily purchase a variety of pesticides in grocery stores, hardware stores, general merchandise stores, etc. They buy them and use them because of an existing insect or rodent problem. Their major concern is getting rid of the pests. This is especially true of inner city areas, where there is overcrowding and where food, water, and harborage are readily available. The individuals apply as little or as much pesticide as they feel is necessary to solve the problem. The concern is that the sheer volume of pesticides utilized, approximately 2 billion pounds of active ingredients a year in the United States, and the location of the application can lead to multiple hazards to people. Semi-volatile pesticides leave a residue within the home environment, which when released can be inhaled by the people living there. Pesticides and fertilizers used outside the home add to the total exposure of the individuals. Some of the pesticides bioaccumulate in food as well as within the body of the individual.

Some 50% of the 2 million cases of poisoning in the United States are found in children less than 6 years of age and 90% of these cases occur in the home. Many thousands of calls are made to poison control centers in the United States each year concerning potential exposure to common household pesticides by children. Most people store pesticides in unlocked cabinets and within the reach of children. The children are particularly vulnerable because of physiological and behavioral circumstances. (See Chapter 4, “Children’s Environmental Health Issues.”)

Suburban areas, although typically less overcrowded and therefore with less opportunity for the presence of insects and rodents, contain additional problems because of increased usage of the chemicals to improve the visual beauty of the outside environment surrounding the home. There is a growing concern about the contamination of the water supply by these chemicals. Suburban areas were typically, at one time, rural areas and therefore the opportunity for increased levels of mosquitoes and other insects exists. Farms on the urban fringe contribute high levels of organic materials which can act as an excellent source of food, water, and harborage for insects and rodents. Agricultural chemicals become a serious concern for the water supply. Pesticide residues are readily spread through this environment.

In rural areas, agricultural chemicals contaminate people and the environment from use, misuse, storage, and disposal. Of special concern is pesticide drift from the application of pesticides through the air and onto the surface of soil. Very small chemical particles can drift for miles before they reach the soil. Another problem is that the pesticides evaporate during and after application and then reform to create hazardous situations. Residues left on food and vegetables can create additional hazards in the food chain. Family members and other individuals living in the rural setting beside field workers and applicators are subjected to the pesticides and can become sick or injured.

Outdoor residential misting systems for mosquito control are poorly regulated since the regulations vary by states and communities and the EPA has not been involved. The frequency and timing of the use may not be coordinated with actual weather conditions and create problems of chemicals being spread within homes and businesses or of extensive chemical drift. Although label instructions should be followed by individuals using such devices, there is no guarantee that improper chemicals are not being used. The effectiveness of this type of system has never been properly evaluated.

It is absolutely essential that all mosquito control program personnel who are conducting adulticid- ing and larviciding are professionals and are licensed by the appropriate licensing authority. Beyond actually carrying out all survey and spraying activities, these individuals become an important part of the public education and outreach effort of the local health department programs. They explain the program that is in operation and also how and where to eliminate standing water to reduce mosquito populations. There is a constant flow of information to the public about when and where mosquito control spraying will occur and what to do to avoid becoming contaminated by the spray.

In addition to the individuals in the urban, suburban, and rural areas who are exposed to pesticides, there are two other high-risk groups. They are workers in the pesticide industry and farm and migrant workers. Those in the pesticide industry typically, on a daily basis, mix, load, transport, store, apply, and dispose of complex chemicals which may be highly toxic and/or cause serious long-term illnesses. They are exposed to the chemicals through accidental spills, leakages, and poor spraying equipment, which leads to inhalation, skin absorption, and contaminated air, food, and water. Air temperatures and high humidity may contribute to activation of the compounds. These conditions potentially intensify the levels of exposure and the chemicals are added to the normal exposure the individuals experience in their everyday lives. Farm and migrant workers are constantly exposed to high levels of pesticides and fertilizers as they work in the fields and as they live in their homes which are in close proximity to the areas where the pesticides and fertilizers are used in substantial quantities.

Pesticides are used to protect crops and livestock from insects, weeds, and disease. It is estimated that 76% of the total pesticides used in the United States is for agriculture, with 24% used in urban, industrial, forest, and public areas. Even small quantities of these chemicals can contaminate both ground and surface water and cause additional problems with the drinking water supply. Non-point contamination is the application of the chemicals to the land, while point source contamination occurs when there are spills of the concentrated chemicals during production, transportation, storage, and at loading and mixing sites, and at disposal sites. The active ingredients in the products may last for months or even years in the ground and continue to contaminate the water. Additional problems may occur when the chemicals are broken down either by sunlight or microorganisms, or taken up by plants. Soil properties and weather conditions affect the actual problems of use of pesticides over large areas. (See endnote 19.)

Adverse human health effects from pesticides range from headaches, weakness, blurred vision, and irritability to suppression of the immune system, depression, asthma, blood and liver diseases, nerve damage, cancer, and mutagenic and teratogenic effects. Some of these symptoms may be recognized quickly and others not for many years. It appears that the amount of birth defects increases in children who were conceived between April and July of the previous year in rural areas.

Human health risks may be due to the totality of pesticides taken into the body through food, water, air, and direct contact with surfaces that have been treated. Different pesticides may have the same effect on the human body and therefore there is a cumulative effect from being exposed to them. Occupational exposure may add to the previously mentioned exposures and cause additional accumulative problems.

The EPA has evaluated about 490 chemicals to date to determine the potential level of a carcinogenicity hazard. It has not included exposure information. This list is a supplement to the individual full risk assessment of the chemical and it provides the date at which the particular chemical was evaluated. Check the most current chemical evaluation for the one which you are concerned about. (See endnotes 17, 18.)

The cancer risk review is based on: laboratory animal findings; metabolism studies; structural relationships with other carcinogens; and any other information including epidemiological findings in people. The categories of risk include carcinogenic to humans; likely to be carcinogenic to humans; evidence of potential carcinogenicity; inadequate information available; and not likely to be carcinogenic to humans. Currently, the guidelines discuss dose-response, exposure assessment, and risk characterization.

Low-dose chronic exposure to the chemicals can impact the nervous system in a negative way. Long-term, low-dose chronic exposure to the chemicals is not well understood. However, it is thought that the chemicals may contribute to the causation and/or exacerbation of asthma. Low-dose exposure of pregnant women in residential settings may contribute to potential birth defects. They may also contribute to birth and early childhood-related health problems. High-dose exposure can lead to acute poisoning incidents, which has been well documented. This type of problem has been particularly identified in children.

The World Health Organization in 2006 issued a document listing pesticides of public health importance that were safe for the destruction of mosquitoes, flies, fleas, bedbugs, lice, roaches, ticks, mites, and rodents. (See endnote 20.) The state of Oregon trains pesticide operators in the use of aluminum phosphide, Bacillus thuringiensis, diphacinone, malathion, methoprene, naled, per- methrin, pyrethrins and pyrethroids, resmethrin, temephos, warfarin, and zinc phosphide. However, as scientific knowledge expands concerning the use of various pesticides, what was considered to be safe at one time may now be considered to be hazardous to certain groups of people or the natural environment. An example of this would be the pesticide chlorpyrifos which is an organophosphate used to control insects, ticks, and mites. It has been used in both agricultural and non-agricultural areas since 1965. It can over-stimulate the nervous system in people at high exposures and has become an occupational exposure hazard. Frequently, a reassessment is being carried out by the EPA for protecting workers who mix, load, and apply the chemicals and how to best avoid shortterm and long-term risk to their health. This chemical also creates a hazard in vulnerable water supplies.

Pest resistance to certain pesticides and families of pesticides has increasingly become a problem. The pests adapt to the chemicals and develop avoidance systems. Those which are weakest die off and those which are most resistant live on to propagate and create more and more resistant pests.

The rapid reproduction rate can make the time span quite short. Many of the new pesticides that would help eliminate pests may be far more hazardous to people than those that are currently being used.

Best Practices in the Use of Pesticides and Antimicrobials

  • • Develop and use an integrated pest management program before using any pesticides.
  • • Review all active ingredients within the pesticide formula and read the instructions for use before selecting the least toxic and most effective chemical to treat the area for specific pests.
  • • Determine if there is the potential for cumulative risk from the use of different pesticides that act in the body in the same manner before deciding which pesticide to use. See the work of the US EPA in this area and use their most current material as a guide in the selection process. Human health risk assessment is based on: hazard identification from each of the chemicals or components in the pesticide; dose-response assessment; exposure assessment; and risk characterization based on the scientific data available.
  • • Avoid overuse of pesticide applications which can be modified.
  • • Understand pesticide persistence in the environment as well as mobility and adsorption before using it.
  • • Ensure that the pesticide applicator is highly trained, licensed, and knows exactly where to apply the chemicals, the amount of soil moisture, as well as the prevailing weather conditions to avoid over-concentration as well as chemical drift.
  • • Establish buffer zones of 50-100 feet from wells and surface water when spraying.
  • • Avoid repetitive use of the same pesticide or the same family of pesticides to help prevent resistance from insects and weeds.
  • • Calibrate and maintain all pesticide application equipment in excellent condition to get the proper amount of pesticide released for the particular situation.
  • • Provide backflow prevention devices on irrigation systems which apply insecticides.
  • • Avoid retreatment of areas by utilizing the proper quantity of pesticides initially.
  • • Use personal protective equipment including gloves, goggles, respirators, and special clothing when handling, storing, applying, and disposing of pesticides. Wash the chemicals off of the clothing and gloves and allow them to dry before storage. Do not let the chemicals enter bodies of water. Change clothing and shoes before entering the house and wash appropriately.
  • • Provide emergency eye and skin washing in the event of contamination from the chemicals during storage, mixing, use, or disposal. Have immediately available special phone numbers for emergency assistance.
  • • Handle and use pesticides only in well-ventilated areas when working indoors.
  • • Keep all children, pets, sensitive people, the elderly, and the chronically ill from areas where pesticides are being applied. Protect all food, pet bowls, and clothing from the pesticides. In outdoor areas obey all signs, flags, or postings about a pesticide application.
  • • Never use an outdoor product indoors.
  • • Use insect repellent that are both safe and effective based on information from the EPA. Check for the length of protection and whether there are any allergic reactions to the chemicals or carriers.
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