Evaluation of the systemic toxicity of coal liquefaction-derived materials following repeated dermal exposure in the rabbit.

Abstract

The subchronic toxicity of two materials produced by the EDS direct coal liquefaction process was investigated using adult New Zealand white rabbits as the test species. Recycle solvent (RS: 204-427 degrees C) and fuel oil (FO: 204-538 degrees C) were applied to the intact dorsal surface of rabbits, 5 days per week for 4 weeks. Materials were applied as suspensions (2.5 and 10.0 g 100 ml-1) in white oil. White oil alone was administered to concurrent control groups. Both RS and FO elicited gross signs of toxicity including severe dermal irritation, loss of body weight (16-25%) and mortality (4/20 in the high-dose group treated with RS). Systemic effects included liver enlargement as evidenced by histologic findings of diffuse hepatocytomegaly, cytoplasmic degeneration and hepatocellular vacuolation as well as elevated serum cholesterol. There was also evidence of testicular, seminal vesicle and thymic atrophy. More pronounced effects were apparent in the high-dose groups. Testes and epididymides from four of the five FO-treated male rabbits were unremarkable at the microscopic level. The testes, epididymides and seminal vesicles of the fifth animal were atrophic. Three of ten RS treated rabbits showed testicular atrophy associated with hypospermatogenesis in the testes, aspermia in the epididymides and vesiculitis in the seminal vesicles. Four additional animals showed evidence of seminal vesicle atrophy. The liver enlargement was probably due to compensatory metabolism; however, exposure to similar materials at higher levels has resulted in liver toxicity. Thymic and testicular atrophy may have been a secondary response to dermal irritation, stress or body weight loss.