All of the above would be the correct answer. In fact, all of the substances listed illustrate the adage, “The dose makes the poison.” Take the first answer choice: Antibiotics are drugs used to treat bacterial infections. But many antibiotics have side effects, some of which can be quite dangerous—these antibiotics tend to be used only as a last resort. While most chemicals used to clean medical equipment probably would not be indicated for human use, there are a few examples: A very common example would be ethanol; ethanol is what makes alcoholic beverages intoxicating, but it is also an effective disinfectant used in medical settings at concentrations far greater than it is present in most drinks. The third answer choice is a clear example of a toxic substance one might find used in a medical setting. There is an entire class of radiopharmaceuticals, or drugs that comprise radioactive isotopes. An example of such a drug would be sodium iodide where a radioactive isotope of iodide is the anion. Iodine (in the form of iodide) in the body is taken up and concentrated in the thyroid gland. When one ingests a radioactive isotope of iodide, it is concentrated in the thyroid, where the unstable atom decays, emitting ionizing radiation that destroys cells. As such, this radiopharmaceutical is used to treat conditions where the cells in the thyroid need to be killed because their presence is pathological, such as in some instances of hyperthyroidism and thyroid cancer. The dosage of any radioactive drug must be very carefully determined and the medication handled and administered properly, as ionizing radiation is harmful to all cells.
