Which item is not a secondary source of contamination?

• A. Soil
• B. Rock
• C. Drums
• D. Field equipment

Answer: (C)

In this context, the concept being tested is how contamination can be introduced into samples during collection and handling. A secondary source of contamination is something that can transfer contaminants to samples after the primary source has released them or that can move residues between samples.

Drums are used to collect, transport, and sometimes store samples, and when they’re clean or new (or properly decontaminated with clean liners), they’re not introducing new contaminants between samples. They’re designed to keep samples isolated from each other, so they don’t act as a vector for cross-contamination. In contrast, field equipment can carry residues from one site to another if not cleaned, making it a secondary contamination source. Soil and rock are the actual materials being sampled and can carry contaminants inherent to the environment; they’re the primary materials of interest, not secondary transfer vehicles.

So, when proper decontamination and handling are in place, drums are not a secondary source of contamination.