Repeated exposure to butenolide vapour: subacute study in Syrian golden hamsters.

The subacute inhalation toxicity of butenolide was examined in hamsters by repeated exposure of 4 groups of 10 males and 10 females to butenolide vapour at concentrations of 0, 5.4, 25 and 130 ppm respectively (6 h/day, 5 days/week) for a period of 13 weeks. The effects found at 130 ppm included eye irritation, salivation, nasal discharge, growth retardation, decreased number of eosinophils, increased liver weight, and hyper- and metaplastic epithelium in the nasal cavity. At the 5.4 and 25 ppm levels no changes were observed which could be attributed to butenolide; 25 ppm was, therefore, considered the highest no-toxic effect level observed. The actual no-adverse effect level was placed at 75 ppm.