Environmental Protection Agency (EPA) Model Lead Based Paint Risk Assessor Practice Test

What is a blank in the context of lead testing?

1. A sample that has been contaminated

2. A non-exposed sample analyzed to check for contamination

3. A negative control for substrate effects

4. A sample tested with known lead levels

The correct answer is: A non-exposed sample analyzed to check for contamination

In the context of lead testing, a blank refers to a non-exposed sample that is analyzed specifically to check for contamination. This type of sample is essential in ensuring that the testing results are accurate and that any detected levels of lead can be attributed to the sample in question rather than background contamination from the environment, equipment, or procedures used during the testing process. By including blanks in an assortment of tests, laboratories can identify any potential interference or contamination that may affect the accuracy of the lead measurements. This helps maintain the integrity of the testing process and assures that the results reflect true levels of lead rather than artifacts introduced during sample collection or analysis. For clarity, a blank is distinct from other types of samples, such as those with known lead levels or those meant to serve as controls for substrate effects. These other classes of samples serve different purposes regarding validation and quality control in testing methodologies.