Final answer:
Gender does not qualify as a host factor in the context of dose response as determined by Host/Environmental Factors, while age, genetics, and diet are host factors that influence how individuals react to different doses of a substance.
Step-by-step explanation:
When assessing a host's response to a chemical agent, various factors are taken into account. Age, genetics, gender (or sex), and diet are typically considered host factors, as they influence how an individual reacts to specific doses of a substance. Among these, gender is the one that does not qualify as a host factor in the context of a dose response as determined by Host/Environmental Factors. This is because gender is sociocultural while sex refers to the biological differences between males and females, which can influence the pharmacokinetics of a drug. Factors such as genetics and diet, on the other hand, can lead to a significant variation in how substances are metabolized and therefore, strongly impact dose-response relationships.