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The methyl, ethyl, and butyl ethers of triethylene glycol (TM, TE, and TB, respectively) were evaluated in three screening studies to assess their potential hazards to humans. The assessment!; included (1) an in vitro procedure to determine the ability of the materials to penetrate human skin, (2) a 21-day dermal limit test in rabbits to determine potential systemic toxicities, and (3) a screening procedure to evaluate the chemicals' potentials to induce developmental toxicity. In the in vitro dermal absorption procedure, the three test materials crossed human epidermis at molar rates 170-330 times more slowly than the lower molecular weight homolog ethylene glycol methyl ether (EM), a chemical known to induce systemic effects following skin application. In the 21-day dermal study, daily applications of 1000 mglkg TM, TE, or TB did not produce systemic toxicity in male or female rabbits, including hematologic or testicular effects. The low dermal penetration rate of the triethylene glycol ethers may have played a role in this outcome. In the developmental toxicity screening test, oral doses of 1000 mg/kg given on Days 6-15 of gestatiorn did not produce maternal toxicity in rats and had no effect on viability or growth of offspring,, pre-or postnatally, indicating low developmental toxic potential for these compounds. The results of these studies indicate that triethylene glycol methyl, ethyl, and butyl ethers have ver,y low capacities to be absorbed through the skin of exposed individuals, low potentials to produce systemic toxicity following oral or dermal exposures, and do not appear to be selectively toxic to the developing conceptus. The data clearly indicate that triethylene glycol ethers do not exhibit toxicologic profiles comparable to those of the methyl and ethyl ethers of ethylene glycol.

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The safety of monotertiarybutylhydroquinone as an oil‐soluble food grade antioxidant was evaluated in acute studies with rats and dogs, in subacute feedings in rats, in rat reproductive efficiency and placental transfer studies, and in subacute feedings with monotertiarybutylhydroquinone heated in vegetable oil. In lifetime feedings in rats and 2 year feedings in dogs, wt gain, feed consumption, behavior, mortality, hemograms, clinical chemistries, gross, microscopic, and electron microscopy were evaluated. There were no toxic or untoward effects. Monotertiarybutylhydroquinone was handled similarly by rats, dogs, and humans. Rats eliminated single oral 0.1–0.4 g/kg doses mostly in the urine in 3–4 days as the 4‐0‐sulfate (57–80%) and the 4‐0‐glucuronide (4%) and with 4–12% unchanged. 2,3,5,6‐14C‐Monotertiarybutylhydroquinone was eliminated similarly with <0.1% as14CO2 and <0.2% remaining in the animal after 4 days. Oral 0.1 g/kg doses to dogs gave a somewhat higher glucuronide contribution. The elimination pattern was little altered in long term feedings. Humans eliminated 0.002 g/kg single doses (high fat vehicle) almost completely in the urine in 2–3 days, with <0.1% unchanged, 73–88% as the 4‐0‐sulfate, and 15–22% as the 0‐glucuronide. Monotertiarybutylhydroquinone residues in most tissues of long term animals were below lower detection limits or negligible. Monotertiarybutylhydroquinone did not induce liver microsomal mixed function oxidases in short and long term rat and dog feedings. The feeding studies and comparative biochemical studies showed monotertiarybutylhydroquinone to be safe for its intended use.

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