If a hazard index is greater than one for adults but less than one for children, how should the exposure be characterized?

• A. No significant risk to the community
• B. Unacceptable risk to adults but not to children
• C. Unacceptable risk to children but not to adults
• D. Unacceptable risk to both adults and children

Answer: (B)

Hazard index compares exposure to a reference dose to gauge potential noncancer health effects. A value above one means the exposure could cause adverse effects in that group, while a value below one suggests effects are unlikely. If adults have a hazard index greater than one, that signals unacceptable risk for adults. If children have a hazard index less than one, their exposure is not expected to cause adverse effects. So the exposure should be characterized as an unacceptable risk to adults but not to children. Risk is evaluated separately for different groups because people vary in sensitivity and reference doses.