Health & Environmental Effects of Burning Agricultural Plastics

As with all plastics and other garbage, burning plastic film and containers used on farms and in greenhouses and landscaping is harmful to human health and the environment. Plastic should instead be recycled when possible and sent to the landfill if no recycling options are available.

What are agricultural plastics?

The term “agricultural plastics” (or “ag plastics”) covers a wide variety of products and plastic types. These include:

• Low density polyethylene (LDPE and LLDPE) film used to make silage and hayage bags, bunker silo covers, greenhouse covers, bale wrap, mulch film, and other flexible products.
• High density polyethylene (HDPE), a more rigid plastic used in pesticide containers and nursery pots.
• Polystyrene (PS), another rigid plastic used in nursery containers and flats.
• Polypropylene (PP), used in nursery pots, row covers and woven tarps.

Why is it harmful to burn plastics?

Burning any type of plastic releases toxic and potentially cancer-causing chemicals into the air, where they can be inhaled by humans and animals and deposited in soil and surface water and on plants. Residue from burning contaminates the soil and groundwater and can enter the human food chain through crops and livestock. In addition, certain chemicals released by burning can accumulate in the fats of animals and then in humans as we consume meat, fish and dairy products. Because agricultural burning often occurs near food sources, it is particularly important to reduce this health hazard to food production.

Some of the most dangerous chemicals created and released during burning some types of plastic are dioxins; learn more on the dioxin page in this section. Dioxins, which are byproducts formed when chlorine-containing products are burned, tend to adhere to the waxy surface of leaves and then enter the food chain. Even if certain types of plastic (such as polyethylene or polypropylene) do not contain chlorine, other materials attached to or burned with the plastic may be a chlorine source.

Other chemicals released while burning plastics include benzo(a)pyrene (BAP) and other polyaromatic hydrocarbons (PAHs), which have both been shown to cause cancer. If film or containers are contaminated with pesticides or other harmful substances, those will also be released into the air. If plastics are burned with other materials, additional toxic chemicals may be created from the interaction of the different substances.

Unburned portions of the plastic become litter on the ground and in lakes and rivers. As it disintegrates, animals may eat the plastic and get sick. Larger pieces of plastic can become a breeding ground for diseases, such as by trapping water that provides habitat for mosquitoes.

What if my supplier tells me I can burn my used silage bags, bunker silo covers or other plastics?

In addition to being harmful, it is illegal under Wisconsin law to burn plastics or other garbage in the open without emission controls (ss. NR 429.04(1) and NR 502.11(1), Wis. Adm. Code). If a manufacturer or retailer tells you to dispose of your plastics that way, please tell them it is illegal. You should always recycle or landfill your used plastics.

Are there recycling options for any agricultural plastics?

There is a small but growing number of recycling and reuse options for plastics used on the farm. You can take used pesticide containers to an agricultural Clean Sweep in your area. Visit the Department of Agriculture, Trade and Consumer Protection’s Clean Sweep page (exit DNR) to see when an event will be held in your area.

In Wisconsin and other parts of the country, options for recycling silage bags, bale wrap, bunker silo covers and other plastic films are starting to emerge. The biggest challenge in recycling these materials is cleaning, collecting and transporting the film, which can then be processed and used in products such as plastic lumber and garbage bags. Ask your suppliers about recycling options and let them know you’d like to be able to recycle your used plastics.

How can I get more information or report concerns?

• Contact the Waste and Materials Management Program at (608)266-2111.
• Visit the Waste and Materials Management Program page on handling agricultural plastics.