Organic and inorganic compounds in crumb rubber mulch

Crumb rubber mulch samples contained metals as well as compounds that haven’t been tested for their effects on human health.


Crumb rubber mulch

Shredded tire material, or crumb rubber, can be used for multiple purposes, including construction of golf cart paths and athletic fields. However, this material may contain compounds that can be harmful to humans and the environment.

Researchers at Yale University tested 15 samples of crumb rubber. Nine of the samples were material sold for home use, and six were used for artificial turf on athletic fields. Samples were cleaned and ground and then treated with organic solvent (dichloromethane), strong acid or simulated acid rain, or were allowed to de-gas passively.

Ninety-two compounds were found in material treated with organic solvents. Of the 92 compounds, nine were carcinogens, 20 were irritants (including respiratory irritants that may complicate asthma), and half have not yet been tested for their effects on human health.

Samples that underwent strong acid extraction were found to have lead, cadmium and relatively large amounts of zinc. Other metals may be present, but were unmeasured.

Simulated acid rain extracted only zinc in significant quantities.

In samples that were allowed to de-gas passively, 11 compounds were detected.

The authors of the study suggest avoiding exposure to crumb rubber because of its toxicity.

— Gaboury Benoit, Ph.D., and Sara Demars, Yale School of Forestry and Environmental Studies, New Haven, Conn.

This research was published in Water, Air, & Soil Pollution, 2018, 229:64.

Teresa Carson is GCM’s science editor.