Inhalation Toxicity of High Flash Aromatic Naphtha

Abstract

A petroleum distillate—a high aromatic naphtha—consisting of a 50/50 blended mixture of equivalent products. SHELLSOL A* and SOLVESSO 100**, containing C9 isomers (75 percent)particularly trimethyl benzenes, was examined for systemic toxicity in rats by inhalation exposure. A preliminary 13-week inhalation study with SHELLSOL A had resulted in liver and kidney weight increases in female rats at the high (7400 mg/m3) and medium (3700 mg/m3) exposure levels, and a low grade anaemia in females at all exposure levels (7400, 3700 and 1800 mg/m3). The follow-up 12-month inhalation study in rats described here used atmospheres generated from the SHELLSOL A/SOLVESSO 100 blend of 1800, 900 and 450 mg/m3. Initial reduction in body weight gain occurred in both male and female rats at the higher exposures. Various statistically significant haematological changes were transiently seen in males up to six months, but were not considered biologically significant. High exposure male liver and kidney weights were increased at 6 and 12 months but, in the absence of histopathological changes, were considered to be physiological adaptive responses. No treatment-related histopathological abnormalities were found. It is concluded that chronic exposure to this high aromatic naphtha is without systemic toxicity in rats under the conditions of these studies.