The objective of this project is to characterize doseresponse relationships and toxicity of formic acid administered by inhalation to rats and mice in 14day repeateddose and 90day subchronic studies. Animals will be exposed for 6 hours per day, 5 days per week for 14 and 90 days. At the end of each study, all animals will be given gross and microscopic histopathologic evaluations. Hematology, clinical chemistry, and sperm morphology/vaginal cytology will be performed in the 90day study. The results of each study will be used by NTP to established doses to be used in the next study (i.e., the 14day results for the 90day study; the 90day results for a possible chronic study).