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

What is the primary method to prevent cross-contamination when taking dust wipe samples?

1. Throw out the first wipe and use a new wipe

2. Use the same wipe for multiple samples

3. Clean the surface with water before sampling

4. Avoid using a clean centrifugal tube

The correct answer is: Throw out the first wipe and use a new wipe

The primary method to prevent cross-contamination when taking dust wipe samples is to dispose of the first wipe and use a new one for sampling. This practice is critical in ensuring that any contamination from the previous surface or check doesn't carry over to the sample being collected. The first wipe may contain lead or other contaminants from surfaces that have not been properly cleaned or sampled, leading to inaccurate measurements and potential misinterpretation of the lead levels present. By discarding the initial wipe, it helps ensure that the sample collected reflects only the contaminants present on the surface being tested, minimizing the risk of cross-contamination and providing a more accurate assessment of lead exposure risks. In contrast, using the same wipe for multiple samples can introduce contaminants from one sample area to another, which compromises the integrity of the testing process. Cleaning the surface with water may remove some lead but also introduces the possibility of further contamination or changes in the dust composition. Avoiding the use of a clean centrifugal tube has no direct relationship with preventing cross-contamination when taking dust wipe samples, as it does not pertain to the wipe sampling procedure itself.