Risk assessment methodologies for carcinogenic compounds in indoor air

Area of Science:

• Environmental Health
• Toxicology
• Risk Assessment

Background:

• Indoor air quality is crucial for public health.
• Potentially carcinogenic substances can be present in indoor environments.
• Accurate methods for determining safe exposure levels are essential.

Purpose of the Study:

• To compare different methodologies for calculating maximum allowable concentrations of specific carcinogenic compounds in indoor air.
• To evaluate the suitability of various risk assessment approaches for indoor air quality standards.
• To use benzene, tetrachloroethylene, trichloroethylene, and vinyl chloride as model substances.

Main Methods:

• Quantitative risk assessment using carcinogenic potency estimates.
• Utilizing lowest observable effect levels (LOEL) from animal and human studies with safety factors.
• Estimating concentrations based on occupational exposure limits and safety factors.
• Comparing calculated values with actual indoor air concentrations measured in Denmark.

Main Results:

• Indoor air concentrations of 10 ppb benzene, 20 ppb tetrachloroethylene, 200 ppb trichloroethylene, and 40 ppb vinyl chloride correspond to a 10(-4) lifetime cancer risk.
• Quantitative risk assessment and LOEL-based methods produced comparable and reasonable maximum allowable concentrations.
• Occupational exposure limit-based calculations generally yielded similar or slightly higher values.

Conclusions:

• Quantitative risk assessment (10(-4) lifetime risk) and LOEL with safety factors are effective for determining safe indoor air concentrations of carcinogens.
• Occupational exposure limits provide a viable, often comparable, alternative for setting indoor air quality guidelines.
• A 10(-6) lifetime risk target for quantitative risk assessment is deemed unreasonable for indoor air quality due to everyday life risks.