Review Contaminant-Specific Toxicological Information

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In this step, you will examine the available toxicological information to see if there is anything about your contaminant that could influence whether exposures could result in harmful effects. There are various types of information to consider:

  • Toxicokinetics (absorption, distribution, elimination, metabolism)
  • Mechanisms of action
  • Children’s susceptibility, including mutagenicity
  • Populations that are unusually susceptible
  • Interactions with other contaminants
  • General population and population with more than average exposure

Note: Typically, health assessors will find the contaminant-specific information they need in previously published ATSDR documents. You can use this information in your written materials after checking that it is up-to-date.

Now, we’ll examine our two main toxicological information sources for our potential COC—the Toxicological Profile and EPA IRIS—and show some examples of the type of information you might pull for this step.

It is important to note that we will not be presenting a full list of all the information you might collect or all the sources that might be available. For training purposes, we will show examples of information we might consider based on our COC and drinking water ingestion (oral) scenario. At real sites, the information to collect will vary by your COCs, exposures, and concerns.

If you have questions during your evaluation, always reach out to a team toxicologist for assistance.

Practice

We pulled the following information for carbon tetrachloride using our ATSDR and EPA sources:

  1. It is readily absorbed (about 85%-91%) through the gastrointestinal tract from oral exposure.
  2. The largest fraction of an absorbed oral dose was initially distributed to fat, but then traveled to blood, muscle, liver, and brain.
  3. It is metabolized mainly by the liver, but also by other tissues, such as the lung and kidney.
  4. Most of it leaves the body unchanged, but some can change to other contaminants before leaving the body.
  5. It leaves the body in expired air, feces, and urine. It may take weeks for some to be eliminated, especially if stored in body fat.
  6. Metabolism of carbon tetrachloride is required for toxicity.
  7. Children are expected to have similar health effects from exposure via drinking water ingestion (pathway for this example) as adults (not increased susceptibility).
  8. Infants can possibly be exposed via breastfeeding, but exposure levels are likely to be low.
  9. Evidence suggests toxicity is dramatically increased by interactions with alcohols, ketones, and a variety of other contaminants.
  10. Moderate to heavy drinkers are at significantly increased risk of liver and/or kidney injury following ingestion.
  11. Fetuses of mothers who drink alcohol would potentially be more susceptible to exposure.
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