Safety evaluation of dibenzyl ether.

Dibenzyl ether (FEMA No. 2371, CAS No. 103-50-4) was given in the diet to rats at a rate of 62, 196 or 620 mg/kg/day for 91 consecutive days. Body weights and food consumption were measured weekly; haematological, clinical chemistry and urinalysis values were obtained at wk 6 and 12. Gross and microscopic pathological changes were observed and organ weights recorded. The high-dose females had increased absolute and relative liver weights; this was considered to be related to dose. Other statistically significant events that occurred sporadically within the test groups were unrelated to dose and were considered to be normal adaptive change. No toxicological or pathological effects were noted at any of the dose levels after 91 consecutive days of feeding dibenzyl ether. A no-effect level was achieved at 196 mg/kg/day. In a 60-kg human, this would be equivalent to approximately 11.8 g/day, assuming a direct relationship between dose and body weight across species. Based on the possible average daily intake of 19.2 mg/day, this would confer a safety factor of 600. The safety factor based on the more realistic consumption per capita of 23.6 micrograms/day would be approximately 500,000.