What term describes prolonged exposure to harmful substances in minute quantities?

The term that describes prolonged exposure to harmful substances in minute quantities is chronic exposure. Chronic exposure refers to situations where an individual is exposed to a toxic substance over an extended period, which could be weeks, months, or even years. This type of exposure can lead to various health issues as the cumulative effect of low-level exposure can result in significant harm to the body over time.

In contrast, acute exposure usually refers to a short-term exposure to a high level of a harmful substance, which may cause immediate adverse effects. Radiation exposure specifically pertains to the exposure to ionizing radiation and is not a general term for harmful substances. Inhalation exposure refers more specifically to the entry of substances into the body via the respiratory tract, and while it can lead to acute or chronic effects, it does not specifically denote prolonged, low-level exposure. Therefore, chronic exposure is the most appropriate term to describe the scenario presented in the question.