Problem 6 - Clinical Chemistry

Question

Which of the following statements concerning cyanide toxicity is TRUE? a. Inhalation of smoke from burning plastic is a common cause of cyanide exposure, and cyanide expresses its toxicity by inhibition of oxidative phosphorylation. b. Inhalation of smoke from burning plastic is a common cause of cyanide exposure. c. Cyanide is a relatively nontoxic compound that requires chronic exposure to produce a toxic effect. d. Cyanide expresses its toxicity by inhibition of oxidative phosphorylation. e. All of these are true.

Step-by-Step Solution

Answer

The correct statement is option a.

Step 1: Analyze Option A

Option a states that inhalation of smoke from burning plastic is a common cause of cyanide exposure, and that cyanide expresses its toxicity by inhibition of oxidative phosphorylation. Evaluate both parts of this statement. Inhalation of smoke from burning materials like plastic can indeed be a source of cyanide exposure, and cyanide does express its toxicity primarily by inhibiting oxidative phosphorylation.

Step 2: Analyze Option B

Option b states that inhalation of smoke from burning plastic is a common cause of cyanide exposure. This statement is true, but it only covers part of the information regarding cyanide toxicity.

Step 3: Analyze Option C

Option c states that cyanide is a relatively non-toxic compound that requires chronic exposure to produce a toxic effect. This statement is false; cyanide is highly toxic and can cause severe effects even with acute exposure.

Step 4: Analyze Option D

Option d states that cyanide expresses its toxicity by inhibition of oxidative phosphorylation. While this is true, it does not cover all aspects of cyanide toxicity, such as its sources.

Step 5: Analyze Option E

Option e states that all the given statements are true. Since option c is incorrect, this makes option e incorrect as well.

Step 6: Determine the Correct Answer

As option a includes both the source of cyanide exposure and its mechanism of toxicity, and both parts of the statement are true, the correct answer is option a.

Key Concepts

Acute vs Chronic Toxicity

Acute toxicity refers to the severe and immediate effects of a toxic substance following exposure. Cyanide is well-known for its acute toxicity; even a small dose can lead to rapid symptoms and potentially death if not promptly treated.
In contrast, chronic toxicity describes the effects of prolonged or repeated exposures over a longer period. Cyanide is not typically associated with chronic toxicity because its acute effects overshadow long-term exposure risks.
However, understanding both forms of toxicity is important in toxicology and public health.

• Acute toxicity: Immediate, severe effects—cyanide is highly toxic in small doses.
• Chronic toxicity: Long-term, gradual effects—not a primary concern with cyanide due to its acute nature.