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Ground-up rubber tires used as garden mulch and playground mulch remain a concern

Environment and Human Health, Inc. (EHHI)  remains concerned about the ground-up rubber tires that unsuspecting people are buying as mulch and spreading all over their gardens and in children's playgrounds.

EHHI is a nine-member, non-profit organization composed of physicians , public health professionals and policy experts, dedicated to protecting human health from environmental harms. It receives no money from businesses or corporations.

In some states rubber tires are a "Hazardous Waste" and in other states they are a "Special Waste". Whichever the case - one has to get a permit to dispose of rubber tires and there is a cost associated with that disposal.

Yet it is these very same rubber tires that are being cut up and sold to people as "Playground Mulch" and "Garden Mulch."

Why is rubber tire mulch a problem for children?

There are many harmful chemicals in ground-up rubber tire mulch used on playgrounds. Young children are a very vulnerable population and therefore should be protected from chemical exposures whenever possible.

The Connecticut Agricultural Experiment Station analyzed a sample of ground-up rubber tires and found:

  • 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.
  • Zinc: There is a very large amount of zinc that is added in the manufacturing of tires and therefore there is a great deal of zinc.

Other Chemicals that are often found in rubber tires are:

  • Benzene: Carcinogen, Developmental Toxicant, Reproductive Toxicant
  • Phthalates: Suspected Developmental Toxicant, Endocrine Toxicant, Reproductive Toxicant
  • PAHs: Suspected Cardiovascular or Blood Toxicant, Gastrointestinal or Liver Toxicant, Reproductive Toxicant ,Respiratory Toxicant,
  • Maganese: Gastrointestinal or liver toxicants
  • Carbon Black: Carcinogen
  • Latex: Causes allergic reactions in some people

Why is rubber tire mulch a problem for gardens?

  • The rubber mulch has an excess amount of zinc -  and the excess zinc stunts the growth of plants. See North Carolina's Department of Agricultural's study on
    rubber mulch -http://www.ncagr.com/agronomi/pdffiles/rubber.pdf
  • There is the potential for ground water contamination from the chemicals in the ground up rubber tire mulch. For people on residential wells, this is particularly worrisome.
  • If the rubber mulch is used on vegetable gardens there is the possibility that the plants will take-up the chemicals found in the used tire mulch.
  • The companies producing and selling ground-up rubber tire mulch do not fully explain where the rubber mulch comes from nor the potential danger it presents to gardens, soil contamination, ground water and humans.

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