Chapter 10

Pesticides as hazardous Waste

Hazardous wastes are wastes with properties that make them dangerous or potentially harmful to human health or to the environment. Some pesticides are considered by EPA to fit this definition, and are thus subject to laws and regulations regarding their proper handling, transportation, and disposal (Tables 10.2, 10.3).

classification of hazardous wastes

A number of different federal and state agencies have enforcement responsibilities in regard to various aspects of hazardous waste management. The US Department of Transportation enforces regulations for movement of hazardous wastes. In 1976 the US Congress passed the Resource Conservation and Recovery Act (RCRA), which directed that EPA develop and implement a program to protect human health and the environment from improper hazardous waste management practices. EPA has done this. Details of their programs can be found at In California, the Department of Toxic Substances Control (DTSC) ( is responsible for hazardous waste information and enforcement.

Listed waste

EPA publishes lists of specific wastes that they consider hazardous. The lists are:

l      F List (non-specific source wastes). This list consists of materials from common manufacturing and industrial processes such as cleaning solvents.

l      K List (source-specific wastes). These are certain wastes from specific industries such as petroleum refining and pesticide manufacturing.

l      P List and U-List (discarded commercial chemical products) include specific chemical products in an unused form. Some pesticides and pharmaceuticals become hazardous waste when discarded.

l      M List (discarded mercury products; California). Included in this list are items such as fluorescent lamps and mercury switches.

Characteristic waste

In addition to the EPA list, there are four criteria that are considered by them for chemical substances that may not be on one of their lists:

l      Ignitability. These are substances than can create fires under certain conditions because they are spontaneously combustible, or have flash points less than 140ƒF. Waste oils and used solvents may meet this criterion.

l      Corrosivity. Corrosive wastes are acids or bases (less than 2 or more than 12.5, respectively, that are capable of corroding metal tanks, drums, and barrels.

l      Reactivity. Reactive wastes are substances that are unstable under normal conditions. They can cause explosions, toxic fumes, gases, or vapors when heated, compressed, or mixed with water.

l      Toxicity. Toxic wastes are harmful or fatal when ingested or absorbed (e.g., those containing mercury or lead). There are 8 characteristics of toxicity defined in California, and if a waste meets even one of the 8, it is considered a toxic hazardous waste (

EPA has extensive information on hazardous substances on their website, listed above. Pesticide applicators should note that certain pesticides would fall under the category of hazardous waste based on several of the criteria listed here.

Here is a general rule concerning what is and what is not a hazardous pesticide waste, aside from the criteria already covered: if the material in question contains any concentration of pesticide that can no longer be legally used, it must be considered a hazardous waste. If the material in question is considered no longer desirable as a pesticide, such as rinse material from containers and spray equipment, left-over spray solutions, excess pesticides, and cancelled/suspended pesticides, it must be disposed of as hazardous waste.

If you are uncertain as to whether or not some quantity of a pesticide substance qualifies as a hazardous waste, you may:

1.      Call the California DTSC at 916-327-4499

2.      Send an email to the California DTSC:

3.      Examine Material Safety Data Sheets for statements concerning it status as a hazardous waste

4.      Read the pesticide label for information on its status

5.      Write or call the formulator or distributor for information

origin of hazardous wastes in vector control operations

The most obvious origin of hazardous wastes related to vector control operations is pesticide applications. Some of the sources include empty pesticide containers containing hazardous residues, rinse water used to clean spray equipment and vehicles, pesticides remaining in sprayer tanks after an application, and unused stocks of outdated and possibly suspended pesticides. Another source of hazardous wastes is the repair and maintenance facility maintained by most mosquito and vector abatement agencies. In California, used motor oil is considered a hazardous waste. Solvents and other fluids used in connection with vehicle maintenance and repair may also fit the classification of hazardous.

One of the keys to management of hazardous waste is to examine the activities of an agency to determine which of them may be generating waste, and how much is generated on average per month.

proper management of hazardous wastes

Most mosquito and vector control agencies will generate waste that will qualify as hazardous. The US EPA has established categories for agencies that generate hazardous waste based on the amount of hazardous waste generated each month (Table 10.1). These same categories have been adopted by the California DTSC. It is important for agencies engaged in vector control operations to know the amount of waste they generate, because the rules for disposal of hazardous waste vary according to the category. This primarily applies to how long hazardous waste can be stored before it must be disposed of as there is an increased risk potential associated with storage of large quantities of these waste.

Table 10.1. EPA Hazard Generator Categories

Hazardous Waste Generated per Month

Category Name and Maximum Allowed Accumulation time

Less than 220 lbs (about half a drum)

CESQG (Conditionally exempt from requirement)

220 lbs –2,200 lbs (up to 5 drums)

SQG (Small Quantity Generator) 180 days (270 days if waste to be transported 200 miles or more

2,200 lbs or more (over 5 drums)

LQG (Large Quantity Generator)
90 days


Containers Used to Collect Hazardous Wastes

Hazardous materials can be placed in their original containers temporarily, but the most common containers used to store hazardous wastes prior to their disposal are 55-gallon steel or plastic drums and inner liners from these drums.

If you have dedicated containers for pesticide hazardous waste, they must contain the following label:

Federal Law Prohibits Improper Disposal
If found, please contact the nearest police, public safety authority, or the US EPA

Other information that should be placed on waste containers include the date waste was first put in the container, the federal waste code numbers, and the type of waste contained in the container. Even if the waste is not classified as hazardous waste, it is a good practice to label the container with the waste material it contains.


Empty Containers

Regulations that address the management of empty pesticide containers are very complex. The DTSC has prepared a fact sheet "Managing Empty Containers" that contains an extensive question and answer section. This fact sheet is available on their website.

California regulations recognize two categories of containers that are exempt from management rules for hazardous waste: (1) containers that once contained waste that does not qualify as hazardous, and (2) containers that meet the definition of "empty" (see below) and have been subjected to approved management practices. Containers that are exempt can be disposed of at any appropriate solid waste facility.

From the standpoint of management of hazardous wastes, "empty" containers are defined as containers that once held hazardous materials or hazardous wastes and have been emptied by the generator (in most cases the vector control agency that used the pesticide) as much as is reasonably possible. In practice, this means inverting the container until no more liquid or solid material pours out. However, because of the concern that containers that fit the definition of "empty" may still contain some residual hazardous materials that could cause significant harm, they are still not considered non-hazardous unless approved management practices are followed.

Containers that held liquid pesticides classified as acute or extremely hazardous waste must be triple-rinsed with a solvent capable of removing the material before they can be considered ready for disposal. It would be unusual for most vector control agencies to use pesticides fitting the latter category.

Containers that held solid pesticides, or pesticides that have become viscous and pour slowly, or have dried out or otherwise become caked, must be cleaned using various methods, such as scraping, in addition to rinsing to remove all pesticide residues.

Management practices required are flexible, depending upon the way empty containers are handled by a particular agency. Some may return empty containers to the original distributor; others may ship containers to a company that reconditions them. Empty containers of 5 gallons or less can be disposed of at a solid waste facility.

Large Containers

Some mosquito and vector control agencies use special underground tanks to collect hazardous wastes such as rinse water. Underground storage tanks are not considered containers, and their management is covered under other regulations. Bulk containers of 110 gallons or more also are controlled by a different set of regulations.

Storage of Containers Full or Partially Full of Pesticides

Containers of pesticides over time can deteriorate to the point where they can rupture, leak, rust, and otherwise lose their original integrity. Especially if pesticides are stored over long periods of time (years) they should be periodically inspected for signs of deterioration, and if leaking containers are found, their contents should be transferred to a new container.

Containers should be kept closed at all times. If containers are used to contain waste, self-closing funnels should be used to add waste. Waste pesticides should never be allowed to evaporate.

Pesticides should always be compatible with the material the container is made of. If the waste is corrosive, high density plastic containers should be used.

Wastes that are reactive (e.g., acids and bases) should never be kept in the same container.

Containers for waste pesticides should be stored indoors. Adequate aisle space and ventilation should be provided. This makes periodic inspections for leaks and container deterioration easier.

Ignitable and reactive pesticide wastes should be stored at least 50 feet from property boundaries.

Pesticide wastes, depending upon the amount of waste generated per month, have legal time limits they can be stored before disposal.

Required Notifications of Hazardous Wastes

Agencies that generate pesticide hazardous waste should designate an emergency coordinator. This person must know what to do in case of a poisoning, fire, spill, or other emergency, and should be available 24 hours a day, 7 days a week. The following information should be clearly posted in a prominent place, such as near a telephone in the main district office, or near a telephone in the proximity of the storage site for pesticide hazardous wastes:

l      Local fire department number

l      Emergency Coordinatorís name and telephone number

l      Locations of fire alarms and fire extinguishers

l      Location of pesticide spill control materials

Pesticides not classified as Hazardous Wastes

l      May be disposed of as regular solid waste or trash.

l      Are regulated by California law

l      Must be disposed of according to instructions contained on the product label

l      Must be disposed of in a careful manner

proper transportation of Hazardous wastes

In California the transportation of hazardous wastes are regulated by the California Department of Toxic Substances Control (DTSC), and no hazardous wastes may be transported without first getting a permit from DTSC. Because of the complex and expensive requirements for permission to transport hazardous wastes, most mosquito and vector control districts contract with a licensed operator to remove, transport, and dispose of hazardous wastes.

Those who believe they would like to transport and dispose of hazardous wastes in-house should refer to "Hazardous Waste Transporter Requirements", August 2007, available on the DTSC website. After reading the daunting requirements, few pesticide technicians will want to pursue this route.

Pesticide technicians should know that any person who transports hazardous wastes must hold a valid registration issued by DTSC. Further, it is unlawful for any person to transfer custody of toxic waste to a transporter who does hold a valid registration. If in doubt, there is a list of registered hazardous waste transporters on the DTSC website.

proper disposal of hAZARDOUS wastes

This section should be entitled "How to avoid having to dispose of hazardous wastes". As mentioned in the previous section, the actual disposal of hazardous wastes is in the most part handled by commercial firms that specialize in this area. Recall also that agencies that generate less than a threshold amount of hazardous waste in a month are exempt from many of the management requirements.

Here are some practices used by many California mosquito and vector control agencies to minimize the amount of hazardous waste that requires special handling and management:

l      Keep the use of pesticides that qualify as hazardous waste to a minimum.

l      Avoid the use of pesticides that are on the Acutely Toxic Hazardous Waste list of EPA. Nearly all of these products are no longer available for use in California anyway.

l      As much as possible, completely empty sprayer tanks of pesticide during applications. Avoid coming back from a job with partially-filled tanks.

l      Do not collect rinse water from pesticide equipment cleaning in tanks for long-term storage, but use the rinse water for diluting water-soluble pesticides in spray tanks. This can only be done if the pesticide sprayed in the equipment that was cleaned is compatible with the pesticide to be diluted with the rinse water.

l      Take advantage of recycling programs for empty pesticide containers offered by many pesticide distributors.

l      Do periodic inventories of pesticides on-hand, and get rid of outdated or suspended materials. If you have materials that are legal, but no longer used in your program, sell or give them to other agencies that can use them.

l      Constantly check for leaking containers. Either get rid of these materials, or transfer them to new containers.

Table 10.2. Pesticides listed as Toxic Hazardous Waste.

Chemical Name

Type of Pesticide

Trade Name



Several names

Cacodylic acid


Several names











Nematicide (fumigant)

Nemaset®, Nemafume®


Nematicide (fumigant)

DD, others


Nematicide (fumigant)

Telone®, Vortex®



Several names


Insecticide, rodenticide


Ethylene dibromide

Insecticide, nematicide

EDB®, Soilbrom®, others



Isotox®, others

Maleic hydrazide

Plant growth regulator

MH-30®, others

Methyl bromide

Insecticide (fumigant)

Several names








Antimicrobial, fungicide

Several names

Warfarin (0.3% or less)


Several names

Zinc phoshide (10% or less)


Several names

Table 10.3. Pesticides listed as Acutely Toxic Hazardous Waste.

Chemical Name

Type of Pesticide

Trade Name






Aldrex®, others

Aluminum phosphide

Insecticide (fumigant)



Bird repellent




Roxion®, Cygone®, others


Herbicide (desiccant)

Dinitro®, others


Insecticide, acaracide



Insecticide, miticide

Thiodan®, Phaser®



Accelerate®, Aquatholt®, others

Ethyl parathion




Insecticide (systemic)

Warbex®, Cyflee®







Methyl parathion


Penncap M®, others


Insecticide (systemic)




Strobane-T®, Toxakil®, others

Warfarin (more than 0.3%)


Several names

Zinc phorphate (more than10%)


Several names

Note: Data for Tables 10.2 and 10.3 from University of Florida IFAS Extension Document PI-18, Proper Disposal of Pesticide Waste, November 2005.

<< Previous PageNext Page >>