A primary source of volatile organic chemical (VOC) contamination of water supplies is:

• A. agricultural pesticides
• B. industrial solvents
• C. acid rain
• D. agricultural fertilizers

Answer: (B)

Volatile organic compounds are organic chemicals that readily evaporate at room temperature. When industrial solvents—such as degreasers, paints, thinners, and cleaning agents—are mishandled or discharged, they can leak into water supplies through spills, leaks, or wastewater streams. Because these solvents contain VOCs, they persist in water and are a common source of VOC contamination in drinking water. Acid rain changes pH and dissolves minerals, not VOCs; fertilizers mainly raise nutrients and can cause eutrophication, not VOC contamination. Agricultural pesticides may contain volatile components, but the large, direct releases from industrial solvent use make industrial solvents the primary source of VOCs in water.