Risk Assessment for Toluene Diisocyanate and Respiratory Disease Human Studies

Area of Science:

• Occupational epidemiology
• Toxicology
• Risk assessment

Background:

• Toluene diisocyanate (TDI) is a reactive chemical linked to respiratory sensitization and potential lung cancer.
• Occupational exposure to TDI necessitates a thorough risk assessment for various health outcomes.

Purpose of the Study:

• To conduct a risk assessment for health outcomes associated with occupational exposure to Toluene diisocyanate (TDI).
• To estimate exposure-response relationships for sensitization, pulmonary function, and mortality.

Main Methods:

• Extracted exposure and health outcome data from published studies and NIOSH evaluations.
• Calculated summary exposure-response estimates, accounting for survivor bias.
• Estimated attributable incidence of sensitization, proportional pulmonary function loss, and excess lifetime risks.

Main Results:

• Survivor bias significantly impacted respiratory outcome analyses.
• Decreased exposure-response for asthma/sensitization and pulmonary impairment with increasing TDI concentration.
• Survivor bias in a short-term employment cohort prevented lung cancer and respiratory disease risk estimation.

Conclusions:

• Controlling for survivor bias, excess lifetime risks >1/1000 for sensitization and impairment occurred at ~2 ppt TDI.
• Under alternative models, risks >1/1000 were estimated at 10-30 ppt TDI.
• Excess mortality from lung diseases, if TDI-related, could pose risks comparable to sensitization.