What margin of safety ("safety factor") does the EPA use to set tolerances?

The correct answer is that the EPA uses a safety factor of 100 times when setting tolerances for pesticide residues. This safety factor is applied as a precautionary measure to ensure that even the most sensitive individuals in the population are protected. By dividing the established no-observable-adverse-effect level (NOAEL) by this factor, the EPA aims to account for potential uncertainties in the data related to exposure and toxicity.

This approach reflects a commitment to safeguarding public health, especially among vulnerable populations such as children, the elderly, and pregnant women. The use of the 100-fold margin of safety establishes a conservative basis for regulatory decisions and reinforces the principle of caution in chemical exposure management.

In contrast, other options represent safety factors that are not typically employed by the EPA for setting tolerances in pesticides. For instance, a 10-fold or 1,000-fold safety factor may be appropriate in different contexts but do not align with the standard practice of the EPA regarding pesticide regulations. The 10,000-fold factor would be considered overly conservative and is not necessary to ensure public safety in this instance.