Xylene and Tetrahydrofuran are both toxic.

• A. True
• B. False
• C. Not specified
• D. Only Tetrahydrofuran is toxic

Answer: (A)

Toxicity of common histology solvents. Both xylene and tetrahydrofuran are toxic solvents used in tissue processing, so the statement is true. Xylene is a volatile aromatic solvent that can irritate the eyes, skin, and respiratory tract, and with higher or prolonged exposure it can affect the nervous system and liver. Tetrahydrofuran is also highly volatile and can cause irritation as well as central nervous system depression at sufficient exposure; it is additionally a peroxide-forming compound, which adds a safety risk if not stored properly. Because safety data sheets designate toxicity for both, the best answer is that both are toxic. If a choice claimed only one is toxic or that toxicity is not specified, it would conflict with established hazard information for these solvents.