he Environmental Protection Agency (EPA) has to make decisions about thresholds with the purpose of identifying which materials are toxic.
The EPA has to decide, based on a particular toxicity, a limit of exposure to protect people (i.e., safe dose). For example, if more than 10 percent of tap water samples exceed the lead action level of 15 parts per billion, then water systems are required to take additional actions to lower the lead level in the water. How do you think the EPA came up with 15 parts per billion in tap water as the threshold for toxicity? We will try to answer this question in this assignment.
For this assignment:
- Study the toxicity of lead (e.g., https://www.epa.gov/lead). List all of the important toxicities associated with lead exposure.
- Discuss which health effect or symptom you would use as a basis to establish the baseline toxicity of lead in regards to regulating lead in the tap water. In other words, which particular health effect should be used to quantify the risk of lead exposure? Keep in mind that lead is a multiorgan toxicant that can damage various functions in the body. What is your reasoning for using this health effect to establish the threshold (i.e., 15 parts per billion of lead in tap water)?
- What type of testing might you conduct to establish the threshold for lead in tap water (i.e., how did the EPA come up with 15 parts per billion as the threshold for toxicity?)?
- What assumptions do you think exist in deriving the safe level, or threshold, for human exposure from the tests you discussed in the previous question?