Carbon black is obtained by the partial combustion or thermal decomposition of hydrocarbons, it is a known carcinogen and it is found in tires.
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 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.
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 vapor pressure of carbon black is less than "0.1 mmHg". 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.
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. Reusing a tire in an Earthship, where it becomes a beneficial resource, and spends its future in an inert setting is an ideal ultimate use for discarded tires.”
Remember the advantages of building tire walls
• Tires are available everywhere and it is very inexpensive to get them.
• The walls are technically easy to build, allowing you to build without skilled labor, with your family
and even with people from your community.
• The reuse of tires will reduce the amount of tires in landfills, which them, since they are exposed
to elements, still emanate today.
• Tire walls are even more resilient than concrete walls over time.
• The earth-filled tires are more eco-friendly than concrete, they already have been processed by industries for our cars, while concrete is regularly used for all kinds of constructions, and it is composed of elements which must be processed in various ways. Even if concrete is not the most polluting of materials per kilogram, it is now the second most widely used material in the world, just behind water! Thus, it becomes the most polluting building material in the world!