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Sulfolane is a solvent used in the petrochemical industry and a groundwater contaminant in areas near refineries. The current studies were conducted to assess the impact of oral exposure to sulfolane on the immune system using two models: (1) a perinatal drinking water exposure to 0, 30, 100, 300, or 1000 mg/L from gestation day (GD) 6 until ∼13 weeks-of-age in Harlan Sprague Dawley rats; and, (2) a 90-day gavage exposure of adult female B6C3F1/N mice to 0, 1, 10, 30, 100, or 300 mg/kg/day. Immune parameters evaluated included measurement of antibody production against sheep red blood cells (SRBC) and keyhole limpet hemocyanin (KLH), ex vivo measurements of natural killer (NK) cell activity, cytotoxic T-cell (CTL) activity, and T-cell proliferation, as well as measures of splenic immune cell populations, hematological parameters, and histopathology of immune tissues. A decrease in ex vivo NK cell activity was observed in cells from female - but not male - F1 rats following developmental exposure. In adult female mice, splenic NK cell number was lower than the vehicle controls at doses ≥ 100 mg/kg; however, ex vivo NK cell activity was not affected by sulfolane treatment. In female mice, a decrease in the number of large unstained cells at doses ≥ 30 mg/kg was observed. In F1 rats, effects on white blood cells (WBC) were limited to a decreasing trend in leukocytes in females; no effects were observed in males. Under the conditions of this study, a no-observed-effect level (NOEL) of 3 mg/kg/day was identified based on reduced NK cell activity in female F1 rats. Overall, these findings suggest that oral exposure to sulfolane in rodents had minimal effects on the immune system.

Ethylene glycol 2-ethylhexyl ether (EGEHE) is a solvent used in a variety of applications.We report disposition and metabolism of EGEHE following a single gavage or dermal administration of 50, 150 or 500 mg/kg [ 14 C]EGEHE in rats and mice and in vitro in rat hepatocytes.EGEHE was cleared rapidly in rat hepatocytes (half-life ∼4 min) with no sex difference.EGEHE was well- and moderately absorbed following oral administration (rats: 80-96%, mice: 91-95%) and dermal application (rats: 25-37%, mice: 22-24%), respectively, and rapidly excreted in urine.[ 14 C]EGEHE-derived radioactivity was distributed to tissues (oral: 2.3-7.2%, dermal: 0.7-2.2%) with liver and kidney containing the highest levels in both species.EGEHE was extensively metabolised with little to no parent detected in urine. The alkoxyacetic acid metabolite, which has previously been shown to mediate toxicities of other shorter-chain ethylene glycol ethers, was not detected.There were no apparent dose, species or sex differences in disposition and metabolism of EGEHE, except that the exhaled volatile compounds were greater in mice (19-20%) compared with rats (<2%).These studies address a critical gap in the scientific literature and provide data that will inform future studies designed to evaluate toxicity of EGEHE.

Poly- and perfluorinated alkyl substances (PFAS) are environmentally persistent chemicals associated with many adverse health outcomes. The National Toxicology Program evaluated the toxicokinetics (TK) of several PFAS to provide context for toxicologic findings.Plasma TK parameters and tissue (liver, kidney, brain) concentrations are reported for perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA) or perfluorodecanoic acid (PFDA) after single-dose administration in male and female Hsd:Sprague-Dawley ® (SD) rats.Generally, longer T max and elimination half-lives, and slower clearance f, were correlated with longer chain length. Male rats administered PFOA had a prolonged half-life compared to females (215 h vs. 2.75), while females had faster clearance and smaller plasma area under the curve (AUC). Females administered PFHxA had a shorter half-life (2 h vs. 9) than males and faster clearance with a smaller plasma AUC, although this was less pronounced than PFOA. There was no sex difference in PFDA half-life. Female rats administered PFDA had a higher plasma AUC/dose than males, and a slower clearance. PFDA had the highest levels in the liver of the PFAS evaluated.Profiling the toxicokinetics of these PFAS allows for comparison among subclasses, and more direct translation of rodent toxicity to human populations.

Sulfolane has been found as a ground water contaminant near refining sites. These studies investigated the in vitro hepatic clearance and in vivo disposition of [ 14 C]sulfolane in rats and mice following a single oral administration (30, 100, or 300 mg/kg) and dermal application (100 mg/kg).[ 14 C]Sulfolane was well-absorbed in male rats following oral administration and excreted extensively in urine (≥93%). Total radioactivity in tissues at 24 and 48 h was ∼7% and <2%. Disposition pattern was similar in female rats and male and female mice at 100 mg/kg oral dose.Dermally applied [ 14 C]Sulfolane (covered dose site, 100 mg/kg) was poorly absorbed in male (∼16%) and female (∼19%) rats; absorption increased to 59% when the dose site was uncovered in male rats suggesting ingestion of dose via grooming of the dose site. Dermally applied [ 14 C]sulfolane (100 mg/kg, covered dose site) was well absorbed in male (∼70%) and female (∼80%) mice.Urinary radiochemical profiles were similar between routes, species, and sexes; the main analytes present in urine were sulfolane and 3-hydroxysulfolane.Sulfolane was not cleared in hepatocytes from rodents or human suggesting sites other than liver might be involved in metabolism of sulfolane in vivo .

n-Butyl-p-hydroxybenzoate (n-butylparaben, BPB) is an antioxidant used in foods, pharmaceuticals and cosmetics. This study investigated the disposition of ring-labelled [(14)C]BPB in Harlan Sprague Dawley rats, and in rat and human hepatocytes. BPB was rapidly cleared in hepatocytes from rat (t(1/2) = 3-4 min) and human (t(1/2) = 20-30 min). The major metabolites detected in rat hepatocytes were hydroxybenzoic acid and in human hepatocytes were hydroxybenzoic acid and hydroxyhippuric acid. [(14)C]BPB was administered to male rats orally at 10, 100 or 1000 mg/kg, intravenously at 10 mg/kg and dermally at 10 and 100 mg/kg; female rats were administered oral doses at 10 mg/kg. Oral doses of BPB were well-absorbed (>83%) and eliminated chiefly in urine (83-84%); ≤ 1% of the radioactivity remained in tissues at 24 h or 72 h after dosing. About 4% and 8%, respectively, of 100 mg/kg dermal doses were absorbed in 24 h and 72 h, and about 50% of a 10 mg/kg dose was absorbed in 72 h. Metabolites detected in urine included those previously reported, BPB-glucuronide, BPB-sulfate, hydroxybenzoic acid and hydroxyhippuric acid, but also novel metabolites arising from ring hydroxylation followed by glucuronidation and sulfation.