Toxicity and Metabolism of 2-Hydroxy-4-n-octoxybenzophenone

Abstract

2-Hydroxy-4-n-octoxybenzophenone (UV 531) is a stabilizer for synthetic resins. Toxicity and metabolism studies were conducted to evaluate its safety as a component of plastics used in contact with food. The acute oral LD50 of UV 531 for male albino rats and the LD50 by continuous 24-hr contact with the clipped skin of male albino rabbits are both greater than 10 g/kg. The substance is not irritating to rabbit skin or rabbit eyes, and shows no detectable capacity for inducing skin sensitization in man. Albino rats of both sexes tolerated a dietary level of 1·8% UV 531 for 90 days with no effect other than a significant increase (P<0·05) in mean relative kidney weight in males. Rats fed 0·6% or less of the product did not differ from their controls. A diet containing 1·8% UV 531 was unpalatable to dogs, but dietary levels of 0·6% or less had no adverse effect on the dogs during a 120-day test period. Preliminary metabolic studies with male rats indicated that most of the orally-administered UV 531 could be recovered unchanged from the faeces. The small portion that was absorbed was excreted as a glucuronide conjugate in the urine. Consequently, groups of male rats were fed a diet containing 1·25 or 5·0% of UV 531 for periods of up to 30 days. Daily records were kept of UV 531 intake, and urine and faeces were collected separately each day. The metabolic pattern was the same at each dietary level. The mean daily recovery of UV 531 from the faeces was about 90%, and the mean daily urinary excretion of UV 531, conjugated as a glucuronide, was about 10%. The total amount of ingested UV 531 appears to be accounted for by these two forms of excretion.