Define a biohazard.

A biohazard refers to any biological substance that poses a threat to the health of living organisms, including humans, animals, and plants. This definition encompasses a wide range of biological materials, such as bacteria, viruses, fungi, and other microorganisms that can cause diseases or harmful effects. Biohazards can also include biological toxins, which are harmful substances produced by living organisms.

Understanding biohazards is crucial in fields such as healthcare, microbiology, and environmental science, as it helps to identify and manage risks associated with exposure to infectious agents. Proper handling, containment, and disposal of biohazardous materials are essential to prevent contamination and ensure safety.

The other options provided do not accurately represent the definition of a biohazard. Chemical hazards, forms of radiation, and limitations to specific types of infections do not encompass the broader concept of biological threats that biohazards represent.