Evaluation of the subacute and subchronic toxicity of inhaled EDS hydrotreated naphtha in the rat

Abstract

Inhalation studies were conducted to assess the subacute and subchronic toxicity of DES hydrotreated naphtha (HN). In the subacute toxicity study, male and female Sprague-Dawley rats were exposed to various concentrations of HN vapor (0.2, 1.0, and 5.0 g/m 3) 6 hr/day for 5 consecutive days. Following 2 recovery days, the animals were exposed for 4 additional days and then sacrificed on the 12th study day. In the subchronic toxicity study, a similar protocol was utilized; however, the animals were exposed 5 days/week for 13 weeks. Following a 2-week recovery period, the animals were sacrificed. Parameters examined in both studies included survival, growth, clinical observations, urinalysis, blood chemistry at necropsy, and microscopic examination of selected tissues. There was some evidence of systemic effects associated with repeated inhalation exposure to HN, although these effects were mild and were primarily confined to the high-exposure groups. The major systemic effect appeared to be renal toxicity in male rats as evidenced by increased urinary excretion of renal epithelial cells, creatinine, glucose, and protein and decreased urine osmolality. However, the absence of consistent pathologic changes in the kidneys of these animals suggested that the lesions were either slight or reversible during the 2-week recovery period.