Dangers of Recycled Tire Mulch

In a prior posting I vented about how a certain Central Florida gardening supa' star was highly recommending recycled tire mulch on-line (and I suspect in print too). This is the same well-respected gardener who has no problem utilizing synthetic fertilizers that feed the plant but not the soil...and send excess nitrogen or whatever else into our waterways...and keep big agri-business related companies with fat pockets...but I digress, that's a whole other series of postings.

I don't want to paraphrase this info because I just took a bunch of Benadryl and I am not trusting my literary or informational abilities too much at the moment. So...instead I will just shamelessly copy great info from the EHHI (Environmental and Human Health Inc.) site, they are a nonprofit organization that specializes in protecting us from ourselves.

A bit long but well worth the time investment. Here goes it (by the way, this also applies to using recycled tires to make raised beds, sorry):

...The report is designed to place health and environmental exposures to recycled tire crumbs in a scientifically based context. In the spring of 2007, EHHI received numerous inquiries from parents who were concerned about health risks to their children from exposures to the ground-up rubber tire "crumbs" found in their town's synthetic turf fields. It was in response to those inquiries that research was undertaken.

Review of the scientific literature about these new fields found that similar concerns had been raised in other states and in other countries. In addition, health data from workers in rubber fabrication industries and the rubber reclamation industries showed the presence of volatile organic hydrocarbons, semi-volatile hydrocarbons and harmful particulates in the air.

Occupational studies revealed that there were health effects ranging from severe skin and eye irritation and respiratory irritation to three forms of cancer.

Based on these studies, EHHI decided to initiate an exploratory study with the Connecticut Agricultural Experiment Station to examine whether the rubber tire "crumbs" out-gassed harmful chemicals into the air or were capable of leaching into ground water.

The four compounds found in the Connecticut Agricultural Experiment Station study, conclusively identified with confirmatory tests, were: benzothiazole; butylated hydroxyanisole; n-hexadecane; and 4-(t-octyl) phenol. Approximately two dozen other chemicals were indicated at lower levels. Chemicals are tested for their potential as cancer-causing agents (carcinogens), their capability of causing mutations (mutagenicity), and their capability of producing fetal malformation (teratogenicity). The four chemicals found have the following reported actions:

Benzothiazole: Skin and eye irritation, harmful if swallowed. There is no available data on cancer, mutagenic toxicity, teratogenic toxicity, or developmental toxicity.

Butylated hydroxyanisole: Recognized carcinogen, suspected endocrine toxicant, gastrointestinal toxicant, immunotoxicant (adverse effects on the immune system), neurotoxicant (adverse effects on the nervous system), skin and sense-organ toxicant. There is no available data on cancer, mutagenic toxicity, teratogenic toxicity, or developmental toxicity.

n-hexadecane: severe irritant based on human and animal studies. There is no available data on cancer, mutagenic toxicity, teratogenic toxicity, or developmental toxicity.

4-(t-octyl) phenol: corrosive and destructive to mucous membranes. There is no available data on cancer, mutagenic toxicity, teratogenic toxicity, or developmental toxicity.

The exposure potential on a soccer field could be quite large. A square foot of field with between two and three inches if "in-fill" could contain between 11 and 15 pounds of tire crumbs.

Another health hazard from synthetic turf fields with rubber tire "crumbs" is heat. Stuart Graffin, of Columbia's Center for Climate Systems Research, determined that the temperatures present on playing fields with tire crumbs during the summer could approach 160 degrees F.

David Brown, Sc.D., EHHI's public health toxicologist, said, "It is clear the recycled rubber crumbs are not inert, nor is a high temperature or severe solvent extraction needed to release metals, volatile organic compounds or semi-volatile organic compounds. The Connecticut Agricultural Experiment Station study conclusively demonstrates that the tire crumbs and tire mulch release chemical compounds into the air and ground water. Thus, tire crumbs constitute a chemical exposure for humans and the environment."

Dr. Brown continued, "Health endpoints of concern are numerous. Some are acute irritation of the lungs, skin and eyes, and chronic irritation of the lung, skin and eyes. However, knowledge is more limited about the effects of semi-volatile chemicals on the kidney, endocrine system, nervous system, cardiovascular system, immune system and development."

Nancy Alderman, president of EHHI, said, "There is enough information now concerning the potential health effects from chemicals emanating from rubber tire crumbs to place a moratorium on installing any new fields or playgrounds that use ground-up rubber tires until additional research is undertaken."

The North Carolina Department of Agriculture's study shows that ground-up rubber tire mulch increases the potential of zinc toxicity and indicates that it is unsuitable for use in production of nursery plants. Therefore, EHHI is in agreement with this study and others that recommend ground-up rubber tire mulch should not be used for gardens.