Which of the following is NOT a biological hazard?

Biological hazards typically refer to microorganisms such as bacteria, viruses, and parasites that can cause illness in humans due to contamination in food. These hazards are living entities that can multiply in food under suitable conditions, leading to foodborne illnesses.

In this question, chemical residues do not fall into the category of biological hazards. Instead, they are classified as chemical hazards, which can include pesticides, cleaning agents, and additives that may inadvertently contaminate food products. Unlike biological hazards, which are living organisms and pathogens, chemical hazards arise from non-biological substances that can potentially harm consumers if ingested.

Bacterial microorganisms, parasitic microorganisms, and viral microorganisms all represent types of biological hazards, as they are associated with living pathogens that can contaminate food and cause illness. Therefore, the presence of chemical residues is the notable exception in this list, reinforcing the classification of biological hazards versus chemical hazards in food safety.