Is Rubber Mulch Toxic?

Uses

• Rubber mulch replaces wood chips in many gardens and playgrounds. Though arguably an adequate mulching material, shredded rubber performs less effectively than traditional mulching materials in terms of soil chemistry, weed control and microbial content.

Toxicity

• Studies by Colorado State University have shown that rubber mulch is not toxic to plants. But, chemicals in the mulch -- called rubber leachates -- can leach into soil and contaminate groundwater and other waterways. These chemicals are highly toxic to aquatic algae, plankton, snails and fish.

Other Considerations

• Linda Chalker-Scott of Washington State University notes that rubber mulch is highly flammable -- even more so than traditional wood and bark mulch. Rubber mulch, once ignited, is also difficult to extinguish.