Which fiber was historically used in protective jackets for its heat resistance but is carcinogenic?

• A. Silk
• B. Wool
• C. Linen
• D. Asbestos

Answer: (D)

Asbestos was used in protective jackets because its natural fiber structure can withstand very high temperatures without easily burning, providing a strong heat barrier. But the danger lies in the fibers themselves: when asbestos fibers are inhaled, they can lead to serious diseases such as asbestosis, lung cancer, and mesothelioma. That carcinogenic risk made asbestos safety-critical, leading to bans and replacement with safer materials. Other natural fibers like silk, wool, and linen don’t offer the same level of heat protection, and they aren’t associated with the same severe long-term health risks in this protective context, which is why they aren’t used for high-heat protective gear in the way asbestos was.