David W. Fassett

Comparative acute effects of some chemicals on the skin of rabbits and guinea pigs

Abstract A comparison was made between guinea pigs and rabbits in their response to various compounds in regard to acute dermal toxicity and primary irritation. Of the eight compounds tested for acute dermal toxicity, only one (parathion) would have been placed in a higher toxicity classification by the rabbit test than by the intact guinea pig skin test. The information obtained in the primary irritation tests showed that the intact guinea pig skin test is as sensitive as, or more sensitive than, the rabbit skin test in eliciting dermal reactions. It is concluded that the intact guinea pig skin test serves as a useful alternate for the rabbit test and that there is no scientific basis for preferring the rabbit as a test animal.

Safety evaluation and biochemical behavior of monotertiarybutylhydroquinone

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.

Absorption of methyl-2-cyanoacrylate-2-14C from full-thickness skin incisions in the Guinea pig and its fate in vivo

Summary Methyl-2-cyanoacrylate-2-14C polymerized in vivo as a tissue adhesive in guinea pigs was absorbed readily and eliminated by the body. Removal from the site of skin incisions was virtually complete by 107 days and only a trace of radioactivity was detectable at that time.

The toxicology and fate of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate.

Abstract Since 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB) may be an indirect food additive because of its use in food packaging, a study was made of its toxicology and fate. Acute po, ip, skin irritation, sensitization and inhalation studies showed it to be practically nontoxic, a slight skin irritant and not a sensitizer. Rats were fed concentrations of 0.1 and 1.0% in their diet for 103 days. The only consistent finding was a slight but significant increase in the weight of the livers of rats fed 1.0% TXIB. Dogs fed for 90 days at concentrations of 0.1, 0.35 and 1.0% in the diet showed only slight increases in some of the liver weights and a slight increase in the average pituitary weight of males at the highest dose levels. Single po 250 mg/kg doses of 3- 14 C-labeled-TXIB were eliminated within 7–10 days of dosing almost completely in the urine (47–73%) and feces (27–46%), 80% being eliminated within 4 days. 14 CO 2 excretion was insignificant. At sacrifice after 14 days these doses, and 1 of about 900 mg/kg, gave negligible increments of radioactivity in liver, brain, kidneys, lungs and fat. After TXIB dosing, free 2,2,4-trimethylpentane-1,3-diol (TMPD), 2,2,4-trimethyl-3-hydroxyvaleric acid (HTMV), their glucuronides, and a monoisobutyrate of 2,2,4-trimethylpentane-1,3-diol were found in the urine. Feces contained the same monoisobutyrate and unchanged TXIB.

The fate of 2,6-bis-(1′-methyl-14C-heptadecyl)-p-cresol (dioctadecyl-p-cresol-14C) in the rat

Abstract The fate of DOPC, 2,6-bis-(1′-methylheptadecyl)-p-cresol, a hindered phenol intended for use as a stabilizer in food packaging, has been studied in rats. Following oral ingestion of 1.0 g/kg doses there are no significant increases in urinary conjugate output, and a large proportion of the dose appears to be unabsorbed. The ingestion of DOPC-14C-labeled on both 1′-methyl carbon atoms as single undiluted 190–860 mg/kg oral doses is followed by the rapid excretion of almost the entire dose in the feces, 96–100% of the dose being thus accounted for within 3–5 days. Less than 1.0% is accounted for in the urine, and none is detectable in the expired air. The fate of DOPC-14C incorporated in the diet at the 0.01% level and ingested for 15 days is identical with that of large single doses. Traces of radioactivity are disseminated to brain, fat, kidney, and liver at higher single dose levels, to liver at lower single dose levels and to brain and liver after ingestion in the diet. This radioactivity is released at varying rates from the respective tissues and is not retained.

The fate of [14C]thiodipropionates in rats

Abstract Thiodipropionic acid and its esters are preservatives and stabilizers used in food and food packaging. The oral fate in rats, hitherto unknown, of thiodipropionic acid (TDPA), didodecyl thiodipropionate (DDTDP), and of a polyester of thiodipropionic acid with cyclohexane-1,4-dimethanol partially terminated with stearyl alcohol, POLY-TDPS-2000 (TDPS), was elucidated in evaluating TDPS as a polymer stabilizer. Single doses of [1- 14 C]TDPA were rapidly eliminated, 87–95% of 241–650 mg/kg doses being recovered in 4 days in urine (78–88%), and feces (0.1–0.9%) and as 14 CO 2 (3–8%). Radioactivity in tissues and organs was less than 1.5 × background. A 3-mg/kg dose of [1- 14 C]TDPA was handled similarly. Urinary radioactivity at the higher dose was due almost entirely to unchanged TDPA, while the lower dose apparently gave an acid-labile conjugate of TDPA. Single oral doses of [1- 14 C]DDTDP (107 and 208 mg/kg) were rapidly eliminated, mostly in the urine (85–88%), with less in feces (1.8–3.5%) and as 14 CO 2 (3–4%, by day 4); 1-day dietary feeding of 166 mg/kg gave similar results. Tissue and organ levels of radioactivity at sacrifice were close to background, with the exception of fat levels, which were elevated 34 days after dosing. Urinary radioactivity was mostly unchanged TDPA or an acid-labile conjugate. Five-hour feeding in the diet of each of 3 rats of 4.7–5.6 mg/kg of 14 C-labeled TDPS prepared from [1- 14 C]TDPA, was almost entirely eliminated by 4 days in urine (95%) and feces (0.7%) and as 14 CO 2 (approx. 6%). At sacrifice 4 days after dosing, tissue and organ radioactivity was slightly above background, and at 34 days essentially normal. Almost two-thirds of the urine radioactivity was due to [1- 14 C]TDPA or a conjugate. TDPA is in many respects similar to a typical dicarboxylic acid after oral intake in being rapidly absorbed and eliminated in the urine largely unchanged. Simple esters and polyesters of TDPA appear to be readily hydrolyzed in the organism to the parent acid, which is then eliminated similarly to TDPA given orally.

Interaction of N,N-disubstituted p-phenylenediamines with guinea-pig epidermis in vivo.

Abstract Guinea-pigs were repeatedly exposed to solutions of the substituted p-phenylenediamine, 3-methyl-4-amino-N,N-diethylaniline hydrochloride. On chromatograms of acid hydrolysates of epidermal proteins from the treated animals the spots normally due to lysine and arginine differed from those from unexposed animals, but the proteins were otherwise unchanged. 4-Amino-N,N-diethylaniline-1-14C (220 μc/m-mole) applied in vivo to guinea-pig skin was partially absorbed and excreted in the urine, with some retention by the epidermis. After exhaustive washing, isolated soluble epidermal proteins retained radioactivity equivalent to 0·5—3 m-moles developer/200 g protein. This radioactivity did not separate from protein on paper electrophoresis and was unrelated to the amounts of developer applied or remaining uncombined in the epidermis. Radioactivity was liberated from exposed soluble proteins on hydrolysis. Drastic acidic conditions caused losses of radioactivity by volatilization. Enzymic hydrolyses gave initially non-volatile radioactive products associated with protein fragments. Alkaline hydrolysates retained radioactivity. No hydrolysate yielded a characterizable amino acid—developer adduct. Allergenic p-phenylenediamines differ from some previously studied contact allergens in that they do not form stable isolable adducts with epidermal protein amino acids.

Studies of the physiological effects of 2,6-bis-(1′-methylheptadecyl)-p-cresol (dioctadecyl-p-cresol) in the rat and dog

Abstract It has been shown that rats and dogs fed as high as 10,000 ppm of DOPC in the diet for 100 and 90 days, respectively, tolerated the compound with little untoward reaction except for a slight decrease in body weight in one group of rats. No effects were noted on behavior, utilization of food, appearance, and stools nor were there any dose-related effects on hemograms, blood chemistry values or urine composition. No dose-related effects were found in organ-body weight ratios nor were there any significant lesions detected at necropsy or upon microscopic examination of the tissues. It appears that the administration of as much as 1.0% DOPC in the diet has no adverse effect on rats and dogs.

Evaluating the absorption of polymers from the gastro-intestinal tract*

Abstract In order to evaluate the possibility of absorption of two partly oxidized polyethylene waxes of approximate mol wt 2500 (Wax 1) and 2100 (Wax 2), procedures were developed to study (a) recovery of polymer from faeces by extraction and precipitation after feeding either wax to rats in standard or low-residue diets, (b) determination of the disposition and elimination of radioactivity by rats after the feeding of tritiated Wax 1, and (c) assay of polymer in lymph from the cannulated thoracic duct of a dog orally intubated with a mixture of the two waxes. Procedure (a) showed that both waxes were little absorbed (> 91% appearing in the faeces), but the actual absorption ( Taken together, procedures (a) and (c) give good reason for establishing the absorption of these waxes as negligible. Assays of thoracic-duct lymph are of value in establishing limits of absorption of polymers, particularly where recoveries from faeces are inaccurate and labelling is impracticable.