In an outdoor EPA study, which sanitation precaution helps avoid contamination of the test system during harvest?

• A. Using separate clean containers for each test group and harvesting the control beans before the treated ones
• B. Harvesting all beans together in a single container
• C. Not washing hands before harvest
• D. Only wearing gloves, no change in containers

Answer: (A)

Preventing cross-contamination during harvest is essential for reliable test results. Using separate clean containers for each test group keeps samples from different treatments from mixing, so any observed effects can be attributed to the intended treatments. Harvesting the control beans before the treated ones further reduces the risk that residues, dust, or handling residues from treated samples contaminate the control samples. Together, these practices preserve the test system’s integrity.

Choosing to harvest all beans in one container would mix samples and blur treatment effects. Not washing hands before harvest or wearing gloves without changing containers can introduce contaminants or residues and still allow cross-contamination between samples.