Environmental Health and Safety

Pesticides, Herbicides, and Fertilizers

The University consists of several buildings and paved open spaces which are primary areas of storm water runoff. Surrounding vegetation is vital for soaking up the runoff. However, depending on the volume and rate, not all of the water can be prevented from reaching the storm drain. In these cases, the storm water run off can pick up contaminants from the vegetation sites. Obvious contaminants may include leaves, silt, and other types of debris. The not so obvious storm water and groundwater chemical contaminants are also a major concern.

Chemicals that may potentially migrate into our drinking water supplies are pesticides, herbicides, and fertilizers. In all cases, storm water runoff containing these chemicals causes problems. Surface runoff of pesticides and herbicides into water bodies changes natural ecosystems by killing or damaging a wide variety of organisms. They often collect and accumulate in the food chain, becoming more harmful than their ambient concentration would suggest. Fertilizer can also disrupt natural biological communities by increasing plant and microbial growth. This condition, known as eutrophication, can drastically change natural water ecosystems and create new pollution conditions.

Improper application of pesticides, herbicides, and fertilizers may also have an impact on storm water infiltration into groundwater. When these contaminants dissolve in storm water they find their way into the groundwater and then into surface waters, such as ponds, streams, rivers, and lakes. The infiltration of these chemicals may also contaminate soil and deeper groundwater units.

Using Pesticides and Herbicides

The risk of using pesticides and herbicides is greatest when the directions are not followed exactly. Carefully read product labels, which contain information about the persistence and toxicity of the chemical. The words “natural,” “organic,” or “biodegradable” do not guarantee that it is safe. Always choose a “pest-specific” pesticide or herbicide that is designed to kill only the pest causing the damage. Persistence refers to the length of time it takes to break down to one-half its previous concentration (also known as half-life). The half-life should be printed on the product label. Avoid pesticides with half-lives longer than 21 days.

In dealing with pesticides and herbicides at home or on the job, develop a plan for use and safety. At work, only certified applicators may use pesticides and herbicides.

Mixing and Use

The mixing and use of pesticides and herbicides is of major concern because this is the time at which many spills occur. It is critical to follow instructions for mixing and use exactly. Be concerned with cleanup and disposal at all times during the use process. Any leftover chemical, the storage containers used in all stages of the application process, and the application equipment must be considered in the cleanup process. Some Guidelines to follow when using pesticides and herbicides include:

General:

  • Always wear appropriate protective clothing. Never wash contaminated clothing with other clothing.
  • Take precautions to prevent spills. For example, close containers tightly after each use, even if you plan to re-open them soon.
  • Know what to do if a spill occurs.
  • Mix only the amount needed for the job.
  • Follow the directions on the label exactly.

Application:

  • Avoid spraying over impervious surfaces.
  • Do not spray on a windy day.
  • Do not apply to bare of eroding soil.
  • Do not apply near water systems such as wells, streams, and lakes.

Storage

Be extremely careful with the storage of chemicals to prevent leaks, spills, and inadvertent accidents. Keep the pesticides and herbicides in their original containers so you know what they are and how to use them. Mark the date of purchase on each container and use older materials first. If possible, store pesticides and herbicides indoors in a clearly marked area designed as secondary containment. Storage areas should be located at least 150 feet from any drinking water well and at least 200 feet from any area that holds water.

Cleaning and Disposal

According to the Washtenaw County Extension Service, the best methods for cleaning containers and equipment are to triple rinse or pressure rinse in the field. To triple rinse: allow the concentrate to drain from the empty pesticide container for 30 seconds. Fill one-quarter of the container, replace the lid, and shake the container so that all interior surfaces are rinsed. Drain the rinse water into the spray tank for at least 30 seconds. Repeat the process twice for a total of three rinses.

Rinse water must be collected and applied to a compatible site at or below the labeled rate. Empty pesticide and herbicide containers cannot be refilled, reconditioned, recycled, or sent back to the manufacturer. They must be crushed, broken, or punctured so that they cannot be used again.

In general, small containers that are used in the home can be disposed of in the trash pickup after they have been rendered unusable and then wrapped in plastic.

Leftover pesticides and herbicides used in residential settings may be disposed of at your local county hazardous waste collection sites (view our recycling page for a list of some local county's webpages). For on campus disposal, contact EHSEM at 593-0921.

Using Fertilizers

The University employs horticulture specialists to manage fertilizer usage on campus property. Applying unnecessary amounts of fertilizer is not only a waste of money; it can also be detrimental to water quality. Excess fertilizers can wash into waterways, stimulating nuisance weed and algae growth. Excessive plant growth can choke slow moving waters, take up oxygen needed by fish and other aquatic life, and release ammonia which is toxic to fish. Before applying fertilizer, have the soil tested to determine what nutrients must be added.

Apply fertilizer at the proper time. Lawn fertilization programs should begin in early October, not early May. When applying fertilizers, follow the directions exactly and keep fertilizers off paved areas. If a liquid fertilizer is used, be careful to avoid over spray and drift. Sweep granular fertilizer back onto the grass to keep it from being washed into the storm water drainage system.