Final answer:
Solvent run-offs can be both voluntary and involuntary, with residential fertilizer use leading to involuntary pollution of water bodies. Similarly, radioactive exposure has voluntary and involuntary sources, with a portion of exposure being involuntary due to unavoidable environmental factors.
Step-by-step explanation:
True, solvent run-offs can be voluntary or involuntary. Solvents used in various industrial, commercial, and residential applications can enter the environment through deliberate actions, such as improper disposal, or through accidental leaks and spills. When fertilizers are applied to lawns and gardens, they can run-off into water bodies or move through groundwater, causing pollution. This pollution source is typically considered involuntary as it is often an unintended consequence of fertilizer use.
In the context of exposure to radioactivity, as referenced in Table 15.4.1, sources of radioactive exposure are also divided into voluntary, such as medical procedures a patient chooses to undergo, and involuntary, like natural background radiation. A certain percentage of radioactive exposure is involuntary because it comes from sources that are not controlled by individuals, such as cosmic radiation or radon in homes.