Inhalation Toxicology

The Globally Harmonized System (GHS) is a United Nations endorsed system for the classification of material hazards, including toxicity. The U.S. Environmental Protection Agency has also established a toxicity classification system. Current OECD testing guidelines (TGs 403, 433, 436) for inhalation toxicity outline the use of animals to determine LC-50 (concentration required to cause death of 50% of test animals).

The EpiAirway in vitro tissue model is used to determine the IC-75 value (concentration required to reduce tissue viability to 75% of vehicle control-treated tissues) of a test chemical. This value can then be used to predict GHS or EPA classification. The model has been shown to predict GHS Acute Inhalation Toxicity Category 1 and 2 chemicals with 100% sensitivity and 43.1% specificity. It has also predicted EPA Acute Inhalation Toxicity Category I-II chemicals with 100% sensitivity and 50% specificity.

Protocol

Test Model	EpiAirway
Replicates	N=3 tissues per test condition
Exposure Time	3-hour topical exposure to a predetermined 4-concentration range of test chemical, followed by a 24 hour recovery period
Assay Controls	Negative Control – Sterile DI H₂O or Corn oil Positive Control – 14mg/ml Formaldehyde
Endpoints	MTT Tissue Viability Assay
Data Delivery	IC-75 Values Predicted GHS or EPA Classification