Environmental Protection Agency (EPA) Lead Risk Assessor Practice Exam

What is a significant feature of the blank wipes used in sampling?

1. They have a high recovery rate

2. They do not contain aloe

3. They are visibly damaged

4. They are reusable

The correct answer is: They do not contain aloe

The key characteristic of blank wipes in sampling is that they do not contain substances such as aloe or other additives that could potentially interfere with the analysis of lead or other contaminants. Blank wipes are often used as control samples to establish a baseline reading and to ensure that any contamination detected during the testing process can be clearly attributed to the sampled area rather than the sampling method itself. Having no interfering substances is crucial because any foreign material could skew results, leading to false positives or inaccurate measurements. This is why the absence of additives like aloe is emphasized. In environmental sampling practices, ensuring the purity of the materials used for sample collection is essential for achieving reliable and valid results, which underscores the importance of using blank wipes that are free from such contaminants.