Which frequency range is associated with skin surface absorption leading to cataracts or skin burns?

• A. 3 GHz-300 GHz
• B. 100 kHz-3 GHz
• C. 30-300 MHz
• D. 3 kHz-5 MHz

Answer: (A)

When frequency goes up, tissue absorbs energy more in the surface layers. This is because skin depth, the distance energy penetrates before it's absorbed, gets smaller as frequency increases. At microwave to millimeter-wave frequencies—roughly a few gigahertz up to several hundred gigahertz—the energy is deposited mostly in the outer skin, leading to surface heating. That surface heating can cause skin burns and, in addition, the eyes are sensitive to RF heating, so excessive exposure can contribute to cataracts. So the range that best matches skin-surface absorption and its risks is the microwave to millimeter-wave band, 3 GHz to 300 GHz. Lower frequencies penetrate deeper into tissue, producing more generalized heating rather than surface heating, which is why they’re less associated with superficial skin burns or lens heating.