ps. why can't I get links to work?

"Use of Scrap Tires in Civil and Environmental Construction" May 10, 1995. Environmental Geo-technics Report No. 95-2. Geo-technical Engineering Program Department of Civil & Environmental Engineering.

Tires are being recommended to absorb off-gassing produced by waste water from communities, industries, and agriculture activities. Here are some highlights from the report: "If tires are reused as a construction material, the unique properties of tires can once again be exploited in a beneficial manner (Ahmed 1993). The benefits of using scrap tires are particularly enhanced if they can be used to replace virgin construction materials made from nonrenewable resources. Additionally, scrap tires are shown to have significant sorption capacity for organic liquids and vapors (Park, Kim, and Edil 1993). Recent research indicated that shredded tires do not show any likelihood of being a hazardous waste material or of having adverse effects on groundwater quality (Edil and Bosscher 1992)." "There may be some concern about lechate quality since scrap tires are considered a waste material. Laboratory and field evidence available does not show any likelihood of scrap tires being a hazardous waste or having potential for significant adverse effects on water quality (Edil and Bossscher 1992)." "In order to obtain an early evaluation of potential environmental problems, duplicate EP toxicity and AFS leaching tests were performed on tire chip samples by the State Laboratory of Hygiene (Edil, Bosscher, and Eldin, 1990). The duplicate results showed excellent correlation for all substances (see Appendix C [in report]). These test results indicate that the shredded automobile tire samples show no likelihood of being a hazardous waste." "Styrene-butadiene rubber is the most important synthetic rubber used by the tire industry. This material is known to absorb large amounts of hazardous organic chemicals from the surrounding environment (Park, Kim, and Edil, 1992). This can actually impart certain beneficial environmental attributes to shredded tires. In summary, shredded tires leach very small amounts of substances compared to other wastes. By comparison to other wastes for which leach test and environmental monitoring data are available, the tire leach data indicate little or no likelihood of shredded tires to have effects on ground water." "This study indicates potential problems under either acidic or basic conditions, i.e., if waste tires are utilized in locations where exposure to pH is expected." "The shredded tires appear to release no base-neutral regulated organics, including PAH compounds that I suggested would be the most likely substances to be extracted from tires....I suspect that several of the substances were released from surface coatings rather than leached from the tire material.....My summary judgment is that the test results indicate that shredded automobile tires leach very small amounts of substances compared to other wastes. The leaching behavior does not indicate that use of tires in earthen embankments or other structures would constitute a threat to groundwater or surface water. The minor amount of leaching of indicators and some metals suggests that tires are best used in buried locations above the water table, rather than in surface applications or in contact with open water bodies. Use of shredded tires need not be restricted in ways different from those placed on whole tires. The test results indicate that waste automobile tires are extremely unlikely to be classified as a hazardous waste." - from a letter by Robert Grefe, State of Wisconsin in "The Report". "Desirable disposal methods [of tires] should at least include three facets: (1) minimum environmental impact (2) maximum reutilization of potential resources (3) economic feasibility" "based upon all of these studies, it can be said that the potential leaching of toxic pollutants from scrap tires is minimal"

However, to assess the risks to human health and environment posed by the use of recycled tires in Earthships, one must look at the pathways of exposure, and the state in which this potential contaminant exists. The letter states that, "A tire under proper conditions will break down into the above products." "The proper conditions" for rubber to degrade would be: high temperature, exposure to light, or the presence of strong oxidizing chemicals. None of these conditions exist when a tire is entombed in an Earthship wall surrounded by packed earth, vapor barrier, stucco, and paint. The argument has been made that tires must off-gas because "old tires smell." The reason "old tires smell" is due to the photo degradation of rubber. Essentially what happens is that photons from light bombard the rubber and knock atoms from the long rubber polymer molecules. This causes the rubber to degrade, and smaller molecules to vaporize. In the absence of light, this does not happen.

Tires are not exposed to light when used in an Earthship. In order for the tires to affect the indoor air quality of an Earthship, the tires must off-gas vapors which must travel from the tires, through the walls, into the living space of the Earthship. The production of such vapors will be proportional to the vapor pressure of the compounds producing the vapors. The NIOSH pocket guide lists the vapor pressure of carbon black as "0 mm (approx.)." This is an extremely low vapor pressure. In other words, this chemical produces almost no vapor. What this means is that the potential for tires to affect indoor air quality will be severely limited by the extremely low vapor pressure of the source chemical. (MY ITALICS)

The letter also states, "We do not need these products leaching into our water systems." In order for a tire to affect water quality, it must come into contact with water, and release chemicals into the water. In a properly designed and constructed Earthship, there will be no flux of water through the wall. Therefore, no water will contact the tire. In the unlikely event that water should contact the tire, the water will not become contaminated because carbon black is insoluble in water (NIOSH Pocket Guide).