Which of the following measures of toxicity is NOT included in the standard assessments?

The measure of toxicity that is not included in the standard assessments is IDLH, which stands for Immediately Dangerous to Life or Health. This metric is specifically designed to indicate concentrations of hazardous substances that pose an immediate threat to life or health, which typically involve emergency situations rather than routine exposure assessments.

In contrast, TLV (Threshold Limit Value), LD50 (lethal dose for 50% of the population), and STEL (Short-Term Exposure Limit) are all commonly used measures in toxicology and occupational health assessments. TLV is used to suggest safe exposure limits over time, LD50 provides a quantitative measure of acute toxicity by indicating the dose that would kill half of a test population, and STEL is used to indicate safe limits for short durations of exposure. These assessments help guide the handling and exposure limits of hazardous materials in occupational settings, whereas IDLH focuses on immediate risk scenarios.