LD50 and chronic toxicity of reactor terphenyls

Acute ingestion of reactor coolant terphenyls (HB-40) revealed LD50 values of 17,500 mg/kg rat and 12,500 mg/kg mouse for nonirradiated coolant and 6,000 mg/kg mouse or rat for irradiated coolant. Chronic ingestion of the mixtures by mice produced mitochondrial changes in epithelial cells of proximal tubules, and at high doses these cells became necrotic as interstitial nephritis and scarring developed. The nephritis was irreversible and followed 16 weeks' ingestion of 1,200 mg/kg nonirradiated HB-40 or 600 mg/kg irradiated coolant. Hepatic changes were observed only at the ultrastructural level where abundant smooth endoplasmic reticulum was seen. It appears that organic terphenyl coolants are potentially toxic when ingested in high doses. This could only occur as a result of chronic exposure at a level greatly in excess of that currently observed in the reactor working environment.