Which statement about biological effects of ultrasound in laboratory settings is correct?

Which statement about biological effects of ultrasound in laboratory settings is correct?

• A. There have been no biological effects observed.
• B. Biological effects occur at all exposure levels.
• C. Biological effects have been observed under certain conditions.
• D. Ultrasound cannot cause any biological effects.

Answer: (C)

Biological effects from ultrasound in lab settings depend on the exposure conditions. The energy delivered—and how long and at what intensity—can push tissues toward thermal effects (heating) or mechanical effects (such as cavitation and microstreaming). In practice, effects are not universal; they’re observed when exposures are sufficiently strong, prolonged, or when conditions favor cavitation (for example, the presence of gas bodies or lower frequencies). This is why protective safety limits aim to keep diagnostic ultrasound well below levels that could cause measurable bioeffects, yet in research or therapeutic contexts with higher intensities or longer exposures, biological changes can and have been observed. So the statement that biology effects have been observed under certain conditions best captures the reality, unlike the other options which incorrectly claim no effects or effects at all exposure levels.

Biological effects from ultrasound in lab settings depend on the exposure conditions. The energy delivered—and how long and at what intensity—can push tissues toward thermal effects (heating) or mechanical effects (such as cavitation and microstreaming). In practice, effects are not universal; they’re observed when exposures are sufficiently strong, prolonged, or when conditions favor cavitation (for example, the presence of gas bodies or lower frequencies). This is why protective safety limits aim to keep diagnostic ultrasound well below levels that could cause measurable bioeffects, yet in research or therapeutic contexts with higher intensities or longer exposures, biological changes can and have been observed. So the statement that biology effects have been observed under certain conditions best captures the reality, unlike the other options which incorrectly claim no effects or effects at all exposure levels.