Which statement best describes how petroleum products cause toxicity?

• A. Direct irritation of the upper respiratory tract only
• B. Microsomal enzyme induction leading to liver injury
• C. Stimulation of appetite
• D. All of the above

Answer: (D)

Petroleum products produce toxicity through multiple mechanisms, so a single effect doesn’t capture the full risk. First, inhaling or contacting these substances can directly irritate the upper respiratory tract, causing coughing, throat irritation, and mucosal inflammation. Second, many components induce hepatic microsomal enzymes (the cytochrome P450 system), which increases metabolism to potentially reactive intermediates that can injure liver cells and lead to hepatotoxicity, especially with chronic exposure or high doses. Third, systemic effects from these chemicals can alter body functions in various ways, including changes in appetite in some individuals. Because petroleum products can cause local irritation, liver injury via enzyme induction, and systemic effects like appetite changes, the statement that all of the above occur best describes their toxicity.