COMMENTS ON THE SCIENCE
     The following are comments received as submissions to the article/blog, "Will California Play Fair with Synthetic Turf?" about the science. They have been excerpted and grouped;
    "The chemicals in tire crumb are delivered to the athlete in the form of dust / particles / in suspension in water / and gases. They are received into the athlete through a combination of inhalation, ingestion, and dermal uptake."
TOXICITY
​
  • "The age, sex, genetic background, previous exposures, diet and other factors play important roles in the way that the athlete’s body interacts with a chemical and in turn the potential for adverse effects. Thus, the characteristics of both the chemical and the exposed individual are important factors in determining the fate of the chemical in the body."

  • "Once a toxic substance has contacted the athlete’s body it can develop unpredictable chronic (long term) effects."

  • "Some chemicals found in tire crumb may not exhibit an effect in the short term, but may cause problems after prolonged exposure such as;
  1. Carcinogens – (agents/compounds that will induce cancer in humans).
  2. Mutagens – (agents that affect the cells of the exposed people in such a way that it may cause cancer in the                                 exposed individual or an undesirable mutation to occur in some later generation).
  3. Sensitizers-Agents (which may cause allergic responses to occur such as an asthmatic-like attack)." 
​
  • "Once a chemical is absorbed into the athlete’s bloodstream, it may be stored in various parts of the body, such as fat or bone, and remain in the individual for many years. Some chemicals readily dissolve in fat so that they will tend to be stored."

  • "A compound may also lead to a toxic effect through interaction with certain organs or tissues in the individual or with other compounds in the athlete’s body."

  • "Often, a substance which is absorbed into the body interacts with particular body chemicals and is changed into one or more other chemicals. These products are called metabolites. Metabolites may be more toxic than the original chemical which was absorbed."

  • "When multiple chemicals have the potential to target the same systems in the body (e.g.,the nervous system) or are capable of causing mutations, cancer, or birth defects, it is particularly important that protective strategies be developed that consider the total burden of chemicals at a location or in a product. (Empire State Consumer project)."

  • "A 2008 study in the Journal of Exposure Science and Environmental Epidemiology found that lead from rubber crumbs was "highly bioaccessible." "When people ingest this (crumb rubber), the gastrointestinal tract, the bile fluids, will get the lead out. That means it will be getting into the body, not just passing through," said the study's chief author, Jim Zhang, a Duke University environmental health professor."
    ​
EXPOSURES (IN GENERAL)

  • "Present understanding of chemical exposures provides only general guidance. The possible toxic effects of exposure to any particular chemical found in tire crumb depend on many factors. Today, scientists are not able to determine exactly how each of these factors (or their combinations) will affect any specific individual athlete"
​
  • "Once a chemical is in the athlete’s body it can be distributed to anywhere in the body by the blood stream."

  • "If there are repeated exposures to the same chemicals, the situation is more complicated. A buildup of the chemicals can occur."

  • "Tire crumb dusts are solid particles often generated by some mechanical or abrasive activity like the grinding of feet into the tire crumb (or as it is being spread on to the field). Particles can settle or remain airborne for prolonged periods of time depending on their size."
 - DERMAL EXPOSURES;

  • "Much of what we place on our skin is absorbed into our bloodstream."

  • "Synthetic turf has an increased incidence of skin abrasion, (turf burn), creating open wounds."

  • "Areas of the athlete’s body such as the forearms are most easily penetrated by chemicals since they can enter down the small duct containing the hair shaft. Chemicals can also enter through cuts, punctures or scrapes of the skin since these are breaks in the protective layer. Sun burn, hives, ulcerations or skin flaking; all weaken the protective layer of the skin and may allow chemicals to enter the body."

  • "Tire crumb dust can also contact and enter the eye and ear." 

  • "Through distribution the chemicals can come into contact with all parts of the body, not only the original site of entry."
 - ​INHALATION EXPOSURES;

  • "Dusts, can enter the respiratory system by accidental inhalation (e.g., breathing in tire crumb dust that has been kicked into the face."

  • An average resting athlete will breathe in about 6 liters of air per minute. An active athlete can breathe in 10,000 liters per minute, along with any contaminants that the air contains."

  • "Smaller tire crumb particles can eventually reach the alveoli, (tiny blood vessel rich air sacs in the lungs). Solid particles which cannot pass through the thin wall of the air sacs may lodge and stay where they are. Some may dissolve. Others may prove too big or too insoluble to be disposed of in this way and simply stay in the air sacs."
​
  • "Types of dusts may damage the surrounding alveolar walls. The damage may be permanent and may cause scars to form, which eventually interfere with the lung's ability to pass oxygen into the blood stream."

  • "In some cases, due to the overwhelming of the ability of the athlete’s body to respond -- the body may not be able to metabolize the chemical rapidly enough to prevent an increase in concentration to toxic levels. In such a situation, there is a clear threshold above which toxic signs and symptoms appear. In the case of (repeated) multiple exposures to a chemical, it is not only the total amount of exposure, but also the rate or timing of exposure that is quite important. All processes in the body normally proceed at specific rates so that metabolism, excretion and storage occur during a particular period of time after a chemical is absorbed." 
 - ​​INGESTION EXPOSURES;
​
  • "Dusts, can enter the digestive system by accidental ingestion (e.g., swallowing tire crumb dust that has been kicked into the face, tire dust contaminated mucus which has been expelled from the lungs, or by eating something with contaminated hands."

  • "Chemicals can enter the digestive system by swallowing contaminated mucus which has been expelled from the lungs. The inside of the small intestine has many hundreds of tiny villi. The villi have very thin walls and are filled with blood vessels. This allows the chemicals to pass from the small intestine across the walls of the villi and enter the veins. The chemicals are then carried around in the blood stream to the parts of the body."

  • "The liver is the principle organ of detoxification, assisted by the kidneys and intestines. When particle material cannot pass through the digestive tract efficiently, instead of being eliminated, it can get trapped inside the folds of the digestive tract and produce toxic by-products."