Which of the following is not included among the nine contaminant groups?

Microorganisms are indeed included among the nine contaminant groups that are typically monitored in environmental health and water quality assessments. This group encompasses a variety of pathogens, such as bacteria, viruses, and protozoa, which can pose significant health risks if present in drinking water or food supplies.

The other options relate to specific types of contaminants that are often categorized separately from microorganisms. Volatile organic chemicals are compounds that can easily evaporate and contribute to air and water pollution. Turbidity refers to the cloudiness or haziness in a fluid caused by large numbers of individual particles, which can interfere with water quality. Lead and copper are specific heavy metals commonly monitored due to their potential adverse health effects, especially in drinking water.

Thus, the correct understanding of the nine contaminant groups would clarify that microorganisms are explicitly included, making it clear why the selected answer would not be the accurate choice. The focus on the specific nature of the groups helps guide the identification of contaminants relevant to public health standards.