Pesticides in the Environment
Learning Objectives:
Know how to define environment and understand the difference between point sources and non-point-sources of contamination by pesticides. Learn why certain areas are sensitive as well as ways pesticides can contaminate offsite areas. Learn what needs to be considered before releasing pesticides as well as factors that influence their movement through the air or water. Learn harmful effects of pesticides on plants, animals and surfaces.
Everything you see—from the inside of your office to your home, your yard, soil, plants and animals—is a part of the environment you live in and affect. Any use of pesticides has an environmental effect that must be considered. Any person that distributes pesticides in any form must take the time to understand safe practices to help protect the environment. The user must know how the pesticide used affects the environment and what the possibilities of it moving out of the treated area are.
All pesticide labels do not necessarily give appropriate information about the possible damage that can be caused by its use. Consequently, all pesticide users need to use their best judgment. The Environmental Protection Agency continues to investigate the effects of pesticides on each part of our environment.
Contamination of the environment by a pesticide is achieved either by point source or non-point-source pollution. Point-source pollution is a specific, limited method of contamination, like pesticide leaked into a storm sewer. Widespread contamination is generally by way of non-point-source pollution. This could mean the spread of a pesticide into several streams after a large outdoor application.
Most contaminations, however, can be attributed to a point source like spills and equipment cleaning sites; improper disposal of containers or cleanups from spills or spills during pesticide mixing. All of these examples are a part of almost every use of pesticides. Therefore, it is essential that pesticide handlers understand and take great care during every stage of a pesticide application or treatment.
Things that need consideration include: sensitive areas on and off site that may be harmed, conditions that could cause pesticide to move offsite, and any possible changes that could be made to prevent contamination.
Any area where living things could be easily injured is a sensitive area. Examples of sensitive outdoor areas include: easily accessed ground water, surface water, institutional areas (schools, hospitals, etc.), apiaries, wildlife refuges, endangered species habitats, food, and ornamental gardens.
If pesticides must be applied to or in a sensitive area, it should only be done by a well-trained applicator with proper equipment. If the site to be treated is a part of or near a sensitive area, a buffer zone should be established around the sensitive area.
For permanent storage and mixing sites that may be near sensitive areas, extra precautions should always be used. Spills must be contained. Products will usually include specific warnings like “Do not use in hospital patient quarters.” Do not overlook these warnings.
Pesticides are capable of moving away from a treatment site both in and out of doors. They may move through the air by wind currents, in water or by animals or plants that move off site.
Drift is the main culprit of pesticide movement. Although it is easy to recognize movement of pesticide by wind while treating an outdoor environment, it is more difficult to recognize movement of pesticide by ventilation systems in an indoor environment.
Dusts, wettable powders, small spray droplets are all more likely to drift, particularly when applied upward or from an aircraft. Heavier formulations, like granules and pellets are less likely to drift offsite. Lighter weight formulations should be applied as close to the ground as possible.
All fumigants and some non-fumigant pesticides have vapors that move most easily in the air. Precautions are necessary during the handling of fumigants, as well as during application. The treated area must always be sealed and handlers must use extra caution to protect people and animals. Labeling will indicate the drift properties of such formulations.
Pesticide pollution is often carried off site through water, often by way of drift, runoff, spills, leaks, leaching, back-siphoning and improper disposal. Runoff is pesticide movement when water moves across a treated surface. Leaching is the movement through water, downward from the surface. When too much rainwater accumulates on a treated surface or too much pesticide is present, runoff or leaching will occur.
Groundwater, ditches, streams and ponds can all be contaminated when runoff occurs outdoors. Indoors, runoff water can enter domestic water systems, usually through careless handling practices. It is also possible to encounter leaching indoors. Pesticides can be absorbed by wood, carpet and other porous surfaces. Again, labels will warn of consequences for leaching and runoff.
Pesticide contamination can also occur when pesticides cling to animal fur, shoes, clothes or equipment. Handlers may unknowingly rub off residue on furniture, food products or people.
Food and feed products have specific legal limits for pesticide residue. Residue on these products is generally the result of too much pesticide being applied, labeling disregarded or when pesticides are moved off site by animals, etc. Warning labels should be noted and followed to prevent movement in these ways.
Plants and animals may be harmed when a pesticide directly contacts them or if it leaves a residue they come in contact with later. Direct contact with nontarget organisms may happen a number of ways. Applications may harm wildlife by destruction of food sources.
If a pesticide must be applied in a large area, warnings and directions must be accurately followed. The formulation should also be chosen with great care to minimize drift and pollution of nontarget plants and animals. Warning labels will offer reminders of runoff effects on crops, livestock, pets and aquatic life.
Residues remain any time an environment is treated or a spill occurs. Generally, pesticides break down over a period of one day to several years. Many factors will affect the speed at which the harmful ingredients breakdown, including moisture, temperature, sunlight, chemical composition and microorganisms.
Some pesticides maintain their chemical structure for long periods of time. These are persistent pesticides and they are effective for long-term pest control. However this same characteristic makes them dangerous to surrounding plants and wildlife. Labels will indicate persistent pesticides.
After multiple applications of persistent pesticides or at a permanent site for mixing and disposal, accumulation can occur. Precautions must be taken to avoid accumulation after spills or cleanups. Accumulation in the soil makes it more susceptible to runoff and creates greater opportunity for contamination as well as harm to local plant and animals.
Pesticides can also harm various surfaces by discoloration, pitting, corroding, etc. Proper labeling will list these effects.