Serum perfluorooctanoic acid (PFOA) concentrations in normal and hyperlipidemic female hamsters dosed orally with ammonium perfluorooctanoate (APFO) for up to 30 days.

In epidemiology studies, the presence of perfluorooctanoate (PFOA) in human blood has been associated with higher serum cholesterol concentrations. A possible explanation for these results is that elevated serum cholesterol might reduce clearance of PFOA. In this study, female hamsters, which transport and regulate cholesterol in a manner similar to humans, were fed normal diet or diet supplemented with 0.05% cholesterol and 10% coconut oil (high-fat diet) resulting in hyperlipidemia throughout the study in supplemented animals. Hamsters on either a normal and high-fat diet were given oral doses of 0.1, 1.0, or 10 mg APFO/kg for 30 days. Serum PFOA concentrations evaluated 24 h after 1, 10, 20, and 30 doses of APFO were not altered in hyperlipidemic hamsters compared to those fed normal diet. For a given dose group, serum concentrations of PFOA were highest following the 10 doses (except for the 10 mg/kg group where concentrations were the highest after the first dose) and were lowest after 20 and 30 doses. Under the condition of this study, higher serum lipids did not affect the absorption and clearance of serum PFOA. Serum PFOA concentrations declined over the course of the study despite continued daily dosing with APFO. This does not support the hypothesis that higher serum lipids might increase the retention of PFOA in the body.

Evaluation of chronic toxicity and carcinogenicity of ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate in Sprague-Dawley rats.

Ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate, developed for use as a polymerization processing aid in the manufacture of fluoropolymers, was tested for its potential chronic toxicity and carcinogenicity in a 2-year oral dosing study in Sprague-Dawley rats. Male rats were given daily doses of either 0, 0.1, 1 or 50 mg/kg; females were given either 0, 1, 50 or 500 mg/kg. Body weights, food consumption and clinical signs were monitored daily; clinical pathology was conducted at designated intervals and animals were given a complete pathological evaluation after 12 months and 24 months of dosing. Normal survival was seen in all groups, no abnormal clinical signs were seen, and body weight gain was reduced only in female rats at 500 mg/kg. Both sexes at the high dose had mild decreases in red cell mass which were somewhat more pronounced in females. Clinical pathology indicative of liver injury was present in males that received 50 mg/kg and correlated with histomorphological liver changes that included both hypertrophic and degenerative/necrotic lesions. Similar histomorphological lesions were seen in the livers of females at 500 mg/kg. Previous shorter term toxicity studies have identified this chemical as a PPARα agonist and the finding of benign tumors of the liver, pancreas and/or testes in males at 50 mg/kg and females at 500 mg/kg is consistent with the rat response to peroxisome proliferators and is of questionable human relevance. Changes in the kidney, tongue, and stomach were observed only at the highest dose of 500 mg/kg in females. The no-observed-adverse-effect-level in this study lies between 1 and 50 mg/kg for males and between 50 and 500 mg/kg for females.

Comparative in vivo and in vitro analysis of possible estrogenic effects of perfluorooctanoic acid.

Previous studies suggested that perfluorooctanoate (PFOA) could activate the estrogen receptor (ER). The present study examined the hypothesis that PFOA can activate ER using an in vivo uterotrophic assay in CD-1 mice and an in vitro reporter assay. Pre-pubertal female CD-1 mice fed an estrogen-free diet from postnatal day (PND)14 through weaning on PND18 were administered 0, 0.005, 0.01, 0.02, 0.05, 0.1, or 1mg/kg PFOA or 17ß-estradiol (E2, 0.5mg/kg) from PND18-20. In contrast to E2, PFOA caused no changes in the relative uterine weight, the expression of ER target genes, or the morphology of the uterus/cervix and/or vagina on PND21. Treatment of a stable human cell line containing an ER-dependent luciferase reporter construct with a broad concentration range of PFOA caused no change in ER-dependent luciferase activity; whereas E2 caused a marked increase of ER-dependent luciferase activity. These data indicate that PFOA does not activate mouse or human ER.

Pathology review of proliferative lesions of the exocrine pancreas in two chronic feeding studies in rats with ammonium perfluorooctanoate.

Two chronic dietary studies, conducted years apart, with ammonium perfluorooctanoate (APFO) in Sprague Dawley rats have been previously reported. Although both included male 300 ppm dietary dose groups, only the later study, conducted in 1990-1992 by Biegel et al., reported an increase in proliferative lesions (hyperplasia and adenoma) of the acinar pancreas. An assessment of the significance of the differences between both studies requires careful consideration of: the diagnostic criteria for proliferative acinar cell lesions of the rat pancreas (for example, the diagnosis of pancreatic acinar cell hyperplasia versus adenoma is based on the two-dimensional size of the lesion rather than distinct morphological differences); the basis for those criteria in light of their relevance to biological behavior; and the potential diagnostic variability between individual pathologists for difficult-to-classify lesions. A pathology peer review of male exocrine pancreatic tissues from the earlier study, conducted in 1981-1983 by Butenhoff et al., was undertaken. This review identified an increase in acinar cell hyperplasia but not adenoma or carcinoma in the earlier study. Both studies observed a proliferative response in the acinar pancreas which was more pronounced in the study by Biegel et al. Definitive reasons for the greater incidence of proliferative lesions in the later study were not identified, but some possible explanations are presented herein. The relevance of this finding to human risk assessment, in the face of differences in the biological behavior of human and rat pancreatic proliferative lesions and the proposed mechanism of formation of these lesions, are questionable.

Evaluation of perfluorooctanoate for potential genotoxicity.

Perfluorooctanoate (PFOA) is a fully fluorinated eight-carbon fatty acid analog with exceptional stability toward degradation that has been used as an industrial surfactant and has been detected in environmental and biological matrices. Exposures to PFOA in the workplace and in the environment have continuously stimulated investigations into its potential human health hazards. In this article, the results of fifteen unpublished genotoxicity assays conducted with perfluorooctanoate (as either the linear or linear/branched ammonium salt (APFO) or the linear/branched sodium salt) are reported and include: seven mutation assays (three in vitro reverse mutation assays with histidine auxotrophic strains of Salmonella typhimurium, two in vitro reverse mutation assays with the tryptophan auxotrophic Escherichia coli WP2uvr strain, one in vitro mitotic recombination (gene conversion) assay with Saccharomyces cerevisiae D4, and an in vitro Chinese hamster ovary (CHO) HGPRT forward mutation assay); seven studies to assess potential for chromosomal damage (three in vitro CHO chromosomal aberration studies, an in vitro human whole blood lymphocyte chromosomal aberration study, and three in vivo mouse micronucleus assays); and an in vitro C3H 10T1/2 cell transformation assay. Although PFOA has not been demonstrated to be metabolized, all in vitro assays were conducted both in the presence and in the absence of a mammalian hepatic microsomal activation system. These assays were originally described in twelve contract laboratory reports which have been available via the United States Environmental Protection Agency public docket (Administrative Record 226) for over a decade; however, the details of these assays have not been published previously in the open scientific literature. With the exception of limited positive findings at high and cytotoxic concentrations in some assay trials which reflected the likely consequence of cytotoxic disruption of normal cellular processes and not a specific genotoxic effect, the results of the studies presented in this paper and other published results clearly demonstrate the absence of direct mutagenic or genotoxic risk associated with PFOA. This finding is consistent with the physical/chemical characteristics of PFOA and is supported by other published genotoxicity studies.

A species difference in the peroxisome proliferator-activated receptor α-dependent response to the developmental effects of perfluorooctanoic acid.

This study examined the effect of prenatal perfluorooctanoic acid (PFOA) administration on pre- and postnatal development using peroxisome proliferator-activated receptor α (PPARα)-humanized mice to determine if species differences in receptor activity might influence the developmental effects induced by PFOA. Pregnant mice were treated daily with water or PFOA (3mg/kg) by po gavage from gestation day 1 (GD1) until GD17 and then either euthanized on GD18 or allowed to give birth and then euthanized on postnatal day 20 (PND20). No changes in average fetal weight, crown-to-rump length, or placental weight were observed on GD18. Expression of mRNA encoding the PPARα target genes acyl CoA oxidase (Acox1) and cytochrome P450 4a10 (Cyp4a10) in maternal and fetal liver was increased on GD18 in wild-type and PPARα-humanized mice but not in Pparα-null mice. On PND20, relative liver weight was higher in wild-type mice but not in Pparα-null mice or PPARα-humanized mice. Hepatic expression of Acox1 and Cyp4a10 mRNA was higher in wild-type mice but not in Pparα-null mice or PPARα-humanized mice on PND20. The percentage of mice surviving postnatally was lower in wild-type litters but not in litters from Pparα-null mice or PPARα-humanized mice. No changes in pup weight gain, onset of eye opening, or mammary gland development were found in any genotype. Results from these studies demonstrate that the developmental/postnatal effects resulting from prenatal PFOA exposure in mice are differentially mediated by mouse and human PPARα.

Toxicology of dimethyl and monomethyl derivatives of acetamide and formamide: a second update.

Dimethylacetamide (DMAC) and dimethylformamide (DMF) continue to be important, widely used solvents involved in a wide variety of industrial applications. As liquids with relatively low vapor pressures, contact with both the integumentary and respiratory systems is the main source of human exposure. Although airborne control levels for the workplace have been established and industrial hygiene practices to limit dermal contact have been put in place, use of these chemicals has been associated with occupational illness, mainly in Asia where new and expanded uses have led to overexposures. Thus an update of the basic toxicology data including tables indicating the dose/exposure response characteristics of both DMAC and DMF is currently important. Both chemicals are similar from a toxicology perspective. Human experience has generally shown the materials to be without adverse effect except under conditions where airborne and dermal controls were not properly applied. The use of urinary metabolite monitoring has successfully been employed to measure integrated dermal and inhalation worker exposure. The chemicals are not particularly toxic following acute exposure but high doses can produce damage to the liver, the organ which is first affected by these two chemicals. Repeated dose/exposure studies have characterized both the targets of toxicity and the doses required to produce changes by various routes of exposure. Higher doses of these materials can produce changes in developing systems, infrequently in experiments at doses in which the maternal animal is unaffected, thus care needs to be taken when exposures are to women of child-bearing age. The chemicals appear to be low in genetic activity and inhalation exposures have not shown the materials to produce tumors in rodents except with DMF in a situation in which aerosol formation was encountered. This presentation extends the two previous reviews and, like those, includes updated information on acetamide and formamide and their monomethyl derivatives as well as the commercially important DMAC and DMF. Since a large portion of the newer information deals with effects in humans and biomonitoring, these sections are presented at the start of this review.

Chronic dietary toxicity and carcinogenicity study with ammonium perfluorooctanoate in Sprague-Dawley rats.

In order to assess the potential chronic toxicity and tumorigenicity of ammonium perfluorooctanoate (APFO), a 2-year dietary study was conducted with male and female rats fed 30 ppm or 300 ppm (approximately 1.5 and 15 mg/kg). In males fed 300 ppm, mean body weights were lower across most of the test period and survival in these rats was greater than that seen either in the 30 ppm or the control group. Non-neoplastic effects were observed in liver in rats fed 300 ppm and included elevated liver weight, an increase in the incidence of diffuse hepatocellular hypertrophy, portal mononuclear cell infiltration, and mild hepatocellular vacuolation without an increase in hepatocellular necrosis. Mean serum activities of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase were elevated up to three times the control means, primarily at the 300 ppm dose. A significant increase in Leydig cell tumors of the testes was seen in the males fed 300 ppm, and tumors of the liver and acinar pancreas, which are often observed in rats from chronic exposure to peroxisome proliferating agents, were not observed in this study. All other tumor types were those seen spontaneously in rats of this stock and age and were not associated with feeding of APFO.

Renal elimination of perfluorocarboxylates (PFCAs).

Sex-, species-, and chain length-dependent renal elimination is the hallmark of mammalian elimination of perfluorocarboxylates (PFCAs) and has been extensively studied for almost 30 years. In this review, toxicokinetic data of PFCAs (chain lengths ranging from 4 to 10) in different species are compared with an emphasis on their relevance to renal elimination. PFCAs vary in their affinities to bind to serum albumins in plasma, which is an important factor in determining the renal clearance of PFCAs. PFCA-albumin binding has been well characterized and is summarized in this review. The mechanism of the sex-, species-, and chain length-dependent renal PFCA elimination is a research area that has gained continuous interest since the beginning of toxicological studies of PFCAs. It is now recognized that organic anion transport proteins play a key role in PFCA renal tubular reabsorption, a process that is sex-, species-, and chain length-dependent. Recent studies on the identification of PFCA renal transport proteins and characterization of their transport kinetics have greatly improved our understanding of the PFCA renal transport mechanism at the molecular level. A mathematical representation of this renal tubular reabsorption mechanism has been incorporated in physiologically based pharmacokinetic (PBPK) modeling of perfluorooctanoate (PFOA). Improvement of PBPK models in the future will require more accurate and quantitative characterization of renal transport pathways of PFCAs. To that end, a basolateral membrane efflux pathway for the reabsorption of PFCAs in the kidney is discussed in this review, which could provide a future research direction toward a better understanding of the mechanisms of PFCA renal elimination.

Hepatocellular hypertrophy and cell proliferation in Sprague-Dawley rats following dietary exposure to ammonium perfluorooctanoate occurs through increased activation of the xenosensor nuclear receptors PPARα and CAR/PXR.

Ammonium perfluorooctanoate (APFO), a processing aid used in the production of fluoropolymers, produces hepatomegaly and hepatocellular hypertrophy in rodents. In mice, APFO-induced hepatomegaly is associated with increased activation of the xenosensor nuclear receptors, PPARα and CAR/PXR. Although non-genotoxic, chronic dietary treatment of Sprague-Dawley (S-D) rats with APFO produced an increase in benign tumours of the liver, acinar pancreas, and testicular Leydig cells. Most of the criteria for establishing a PPARα-mediated mode of action for the observed hepatocellular tumours have been previously established with the exception of the demonstration of increased hepatocellular proliferation. The present study evaluates the potential roles for APFO-induced activation of PPARα and CAR/PXR with respect to liver tumour production in the S-D rat and when compared to the specific PPARα agonist, 4-chloro-6-(2,3-xylidino)-2-pyrimidinylthioacetic acid (Wy 14,643). Male S-D rats were fed APFO (300 ppm in diet) or Wy 14,643 (50 ppm in diet) for either 1, 7, or 28 days. Effects of treatment with APFO included: decreased body weight; hepatomegaly, hepatocellular hypertrophy, hepatocellular hyperplasia (microscopically and by BrdU labelling index), and hepatocellular glycogen loss; increased activation of PPARα (peroxisomal ß-oxidation and microsomal CYP4A1 protein); decreased plasma triglycerides, cholesterol, and glucose; increased activation of CAR (CYP2B1/2 protein) and CAR/PXR (CYP3A1 protein). Responses to treatment with Wy 14,643 were consistent with increased activation of PPARα, specifically: increased CYP4A1 and peroxisomal ß-oxidation; increased hepatocellular hypertrophy and cell proliferation; decreased apoptosis; and hypolipidaemia. With the exception of decreased apoptosis, the effects observed with Wy 14,643 were noted with APFO, and APFO was less potent. These data clearly demonstrate an early hepatocellular proliferative response to APFO treatment and suggest that the hepatomegaly and tumours observed after chronic dietary exposure of S-D rats to APFO likely are due to a proliferative response to combined activation of PPARα and CAR/PXR. This mode of action is unlikely to pose a human hepatocarcinogenic hazard.

Male reproductive system parameters in a two-generation reproduction study of ammonium perfluorooctanoate in rats and human relevance.

Ammonium perfluorooctanoate (ammonium PFOA) is an industrial surfactant that has been used primarily as a processing aid in the manufacture of fluoropolymers. The environmental and metabolic stability of PFOA together with its presence in human blood and long elimination half-life have led to extensive toxicological studies in laboratory animals. Two recent publications based on observations from the Danish general population have reported: (1) a negative association between serum concentrations of PFOA in young adult males and their sperm counts and (2) a positive association among women with time to pregnancy. A two-generation reproduction study in rats was previously published (2004) in which no effects on functional reproduction were observed at doses up to 30mg ammonium PFOA/kg body weight. The article contained the simple statement: "In males, fertility was normal as were all sperm parameters". In order to place the recent human epidemiological data in perspective, herein we provide the detailed male reproductive parameters from that study, including sperm quality and testicular histopathology. Sperm parameters in rats from the two-generation study in all ammonium PFOA treatment groups were unaffected by treatment with ammonium PFOA. These observations reflected the normal fertility observations in these males. No evidence of altered testicular and sperm structure and function was observed in ammonium PFOA-treated rats whose mean group serum PFOA concentrations ranged up to approximately 50,000ng/mL. Given that median serum PFOA in the Danish cohorts was approximately 5ng/mL, it seems unlikely that concentrations observed in the general population, including those recently reported in Danish general population, could be associated causally with a real decrement in sperm number and quality.

Pathology Working Group review and evaluation of proliferative lesions of mammary gland tissues in female rats fed ammonium perfluorooctanoate (APFO) in the diet for 2 years.

Perfluorooctanoate (PFO) is a perfluorinated carboxylate that is widely distributed in the environment. A 2-year chronic study was conducted in rats fed either 30 or 300 ppm of ammonium perfluorooctanoate (APFO). To investigate the possible relationship of APFO exposure to proliferative mammary lesions, a Pathology Working Group (PWG) review of the original slides was performed. The consensus reached by the PWG was that the incidence of mammary-gland neoplasms was not affected by chronic dietary administration of APFO. Therefore, feeding female rats up to 300 ppm of APFO resulted in no increase in proliferative lesions of the mammary tissue.

90-day oral gavage toxicity study of 8-2 fluorotelomer alcohol in rats.

8-2 fluorotelomer alcohol is a fluorinated chemical intermediate used to manufacture specialty polymers and surfactants. The potential subchronic toxicity and the reversibility of the effects of this chemical were evaluated following approximately 90 days of oral gavage dosing to Crl:CD(SD)IGS BR rats. A complete toxicological profile, including neurobehavioral assessments and hepatic beta-oxidation, were conducted at selected intervals and a group of rats was included for a 90-day postdosing recovery period. Dose levels tested were 0 (control), 1, 5, 25, and 125 mg/kg. No test-substance-related mortality occurred at any dose level. Rats at 125 mg/kg developed striated teeth, such that these animals were switched to ground chow at 77 days. No treatment-related alterations in body weight, food consumption, neurobehavioral parameters, or hematology/clinical chemistry were found. Hepatic beta-oxidation was increased in males at 125 mg/kg and in females at 25 and 125 mg/kg. In both males and females, plasma fluorine levels were increased at 125 mg/kg and urinary fluorine was elevated at > or =5 mg/kg. Degeneration/disorganization of enamel organ ameloblast cells was observed at 125 mg/kg in males, but not females. Liver weight increases accompanied by focal hepatic necrosis were observed at both 25 and 125 mg/kg, and chronic progressive nephrotoxicity occurred in female rats at 125 mg/kg. With the exception of hepatocellular necrosis in males at 125 mg/kg and the increased incidence and severity of chronic progressive nephropathy in females at 125 mg/kg, all other changes showed evidence of reversibility. The no-observed-adverse-effect level was 5 mg/kg.

Perfluoroalkyl acids and related chemistries--toxicokinetics and modes of action.

The perfluoroalkyl acid salts (both carboxylates and sulfonates, hereafter designated as PFAAs) and their derivatives are important chemicals that have numerous consumer and industrial applications. However, recent discoveries that some of these compounds have global distribution, environmental persistence, presence in humans and wildlife, as well as toxicity in laboratory animal models, have generated considerable scientific, regulatory, and public interest on an international scale. The Society of Toxicology Contemporary Concepts in Toxicology Symposium, entitled "Perfluoroalkyl Acids and Related Chemistries: Toxicokinetics and Modes-of-Action Workshop" was held February 14-16, 2007 at the Westin Arlington Gateway, Arlington, VA. In addition to the Society of Toxicology, this symposium was sponsored by 3M Company, DuPont, Plastics Europe, and the U.S. Environmental Protection Agency. The objectives of this 3-day meeting were to (1) provide an overview of PFAA toxicity and description of recent findings with the sulfonates, carboxylates, and telomer alcohols; (2) address the toxicokinetic profiles of various PFAAs among animal models and humans, and the biological processes that are responsible for these observations; (3) examine the possible modes of action that determine the PFAA toxicities observed in animal models, and their relevance to human health risks; and (4) identify the critical research needs and strategies to fill the existing informational gaps that hamper risk assessment of these chemicals. This report summarizes the discourse that occurred during the symposium.

Review of the toxicology of three alkyl diamines.

Three alkyl diamines, which are by-products formed and separated during the production of hexamethylene diamine, have been tested, mostly for their acute toxicity. This paper reviews methodologies used and the results obtained from these three chemicals. All three tested [2-methyl-1,5-pentanediamine (2-MP), 1,3-diaminopentane (DAMP), and 1,2-cyclohexanediamine (DCH)] were 95% pure and were supplied by the DuPont Company. The acute toxicity of all three chemicals is relatively low with acute oral lethal levels in the rat ranging from 1000 to 2300 mg/kg. Single 4-h inhalation exposures show similarly low toxicity with lethality produced in the rat at concentrations ranging from 2.9 to 4.3 mg/L. These diamines are severe skin irritants in both the rabbit and the guinea pig and are also severe eye irritants (studied only in 2-MP). Dermal sensitization was seen in the guinea pig with DAMP and DCH but not with 2-MP. The irritant dose of these materials was shown in repeated exposure inhalation studies when 2-MP and DCH produced irritation in the upper respiratory tract (point of contact) with some lower lung involvement but no significant systemic effects. 2-MP when fed to rats produced a slight body weight effect at dose equivalents of 800 mg/kg with no other parameters affected. All three materials were inactive in Salmonella, and 2-MP did not produce chromosomal aberrations in cultured human lymphocytes. The main effects of this series of diamines appear related to their irritant properties, and attention needs to be paid to their delayed hypersensitivity potential.

Absorption, distribution, metabolism, and elimination of 8-2 fluorotelomer alcohol in the rat.

The absorption, distribution, metabolism, and elimination of [3-14C] 8-2 fluorotelomer alcohol (8-2 FTOH, C7F1514CF2CH2CH2OH) following a single oral dose at 5 and 125 mg/kg in male and female rats have been determined. Following oral dosing, the maximum concentration of 8-2 FTOH in plasma occurred by 1 h postdose and cleared rapidly with a half-life of less than 5 h. The internal dose to 8-2 FTOH, as measured by area under the concentration-time curve to infinity, was similar for male and female rats and was observed to increase in a dose-dependent fashion. The majority of the 14C 8-2 FTOH (> 70%) was excreted in feces, and 37-55% was identified as parent. Less than 4% of the administered dose was excreted in urine, which contained low concentrations of perfluorooctanoate (approximately 1% of total 14C). Metabolites identified in bile were principally composed of glucuronide and glutathione conjugates, and perfluorohexanoate was identified in excreta and plasma, demonstrating the metabolism of the parent FTOH by sequential removal of multiple CF2 groups. At 7 days postdose, 4-7% of the administered radioactivity was present in tissues, and for the majority, 14C concentrations were greater than whole blood with the highest concentration in fat, liver, thyroid, and adrenals. Distribution and excretion of a single 125-mg/kg [3-14C] 8-2 FTOH dermal dose following a 6-h exposure in rats was also determined. The majority of the dermal dose either volatilized from the skin (37%) or was removed by washing (29%). Following a 6-h dermal exposure and a 7-day collection period, excretion of total radioactivity via urine (< 0.1%) and feces (< 0.2%) was minor, and radioactivity concentrations in most tissues were below the limit of detection. Systemic availability of 8-2 FTOH following dermal exposure was negligible.

Comparative responses of rats and mice exposed to linear/branched, linear, or branched ammonium perfluorooctanoate (APFO).

The purpose of this study was to compare the toxicity of linear/branched ammonium perfluorooctanoate (APFO) with that of linear and branched APFO. Linear/branched APFO (approximately 80% linear and 20% branched isomers) was formerly used in the production of commercial products. The extensive toxicologic database for APFO has been developed essentially using this mixture of isomers. The trend now is to use APFO containing only the linear isomer. The current study was performed to determine if the toxicological database developed for the linear/branched isomer is applicable to the linear isomer. To determine the contribution of branched APFO to the toxicity of linear/branched APFO, a form of APFO that was 100% branched was synthesized. Rats and mice were given doses by oral gavage ranging from 0.3 to 30 mg/kg of either the linear/branched, linear, or branched APFO for 14 days. Clinical signs, body weights, food consumption, selected hematology and serum lipid parameters, liver and kidney weights, hepatic peroxisomal beta-oxidation, and serum PFOA concentrations were evaluated. Mean body weights were about 20% lower in rats and mice dosed with 30 mg/kg of linear/branched or linear APFO compared to controls, and 3-5% lower in animals dosed with 30 mg/kg of branched APFO. In rats, all three forms reduced lipids. In mice, all three forms reduced total and HDL cholesterol similarly but triglycerides were increased at lower doses. Increased peroxisomal beta-oxidation activity and serum PFOA concentrations were seen in both species but these effects were least pronounced in rats dosed with the branched material. In rats, serum PFOA levels were 20-51 ppm at Lowest Observed Effect Levels (LOEL) of 0.3-1 mg/kg, based primarily upon lipid parameters. In mice, serum PFOA levels were 10-14 ppm at the LOEL of 0.3 mg/kg, based primarily upon relative liver weight. In both rats and mice, the overall responses to the linear/branched and the linear forms of PFOA were similar, but the branched form appears to be less potent. Based on these results, and for the endpoints evaluated in this study, the toxicological database developed primarily from testing linear/branched APFO is applicable to linear APFO.

Inhalation toxicity of 1,3-propanediol in the rat.

1,3-Propanediol (504-63-2) was studied to determine the potential effects following repeated inhalation exposures to rats. Rats were exposed 6 hr/day, 5 days/wk for 2 wk (9 exposures) to vapor or vapor/aerosol mixtures of either 0, 41, 650, or 1800 mg 1,3-propanediol/m(3). In vivo responses were observed or measured daily. Clinical pathology and tissue pathology analyses were conducted after the 9th exposure and on half of each group following an 18-day recovery (nonexposure) period. All rats showed normal body weights. No unusual external signs of response were seen, and no deaths were encountered. Clinical pathology (blood counts, serum chemical parameters) and tissue pathology (gross pathology, organ weights, and histopathology) examinations in the 1,3-propanediol exposed rats were similar to those in the unexposed controls. The highest concentration tested, 1800 mg/m(3), which was the highest concentration that could practically be generated, was the no-observed-effect level (NOEL) for this study. 1,3-Propanediol does not appear to pose a significant hazard via inhalation of either the vapor or a vapor/aerosol mixture.

Perfluorooctanoate: Placental and lactational transport pharmacokinetics in rats.

This study was conducted to develop a quantitative understanding of the potential for gestational and lactational transfer of perfluorooctanoate (PFOA) in the rat. Time-mated female rats were dosed by oral gavage once daily at concentrations of 3, 10, or 30 mg/kg/day of the ammonium salt of PFOA (APFO) starting on gestation (G) day 4 and continuing until sacrifice. On days 10, 15, and 21G, five rats per dose level were sacrificed and blood samples were collected 2h post-dose. Embryos were collected on day 10G, amniotic fluid, placentas, and embryos/fetuses were collected on days 15 and 21G, and fetal blood samples were collected on day 21G. Five rats per dose level were allowed to deliver and nurse their litters, and on days 3, 7, 14, and 21 post-partum (PP) milk and blood samples of maternal and pup were collected 2h post-dose. All samples were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) for PFOA concentration. Concentrations of PFOA in maternal plasma and milk attained steady state during the sampling interval. The steady-state concentrations in maternal plasma were 10-15, 25-30, and 60-75 microg/mL in rats receiving 3, 10, and 30 mg/kg, respectively. Steady-state concentrations in milk were approximately 10 times less than those in maternal plasma. The concentration of PFOA in fetal plasma on day 21G was approximately half the steady-state concentration in maternal plasma. The milk concentrations appeared to be generally comparable to the concentrations in pup plasma. Pup plasma concentrations decreased from day 3PP to day 7PP, and were similar on days 7, 14, and 21PP at all dose levels. PFOA was detected in placenta (days 15 and 21G), amniotic fluid (days 15 and 21G), embryo (days 10 and 15G), and fetus (day 21G). These pharmacokinetics allow estimation of the dose to developing and nursing rat offspring following maternal exposure.

Toxicity of hexamethylenediamine.

Hexamethylendiamine (HMDA; CAS No. 124-09-4; 6055-52-3 for the dihydrochloride salt) is moderately toxic following acute doses/exposures with oral lethal doses in rats ranging from 750 to 1500 mg/kg. HMDA is extremely irritating to the skin and eyes and is not a sensitizer in guinea pigs. Repeated exposure inhalation studies have defined the upper respiratory tract to be the first target of HMDA. The irritation seen is proportional to the exposure concentration. Systemic damage is limited. Genetic testing is not extensive, but there is no indication of activity. HMDA is neither a developmental nor a reproductive toxin, but in one developmental study, the fetal No-observed-adverse-effect-level (NOAEL) was lower than that of the maternal animal. No carcinogenicity studies have been conducted. Documented human experience is limited, but indications of HMDA's irritative properties are found in the literature. HMDA does not persist or bioaccumulate in the environment. The chemical is not particularly toxic to fish and aquatic invertebrates but is quite toxic to algae. HMDA is rapidly absorbed and metabolized by the rat with little tissue storage.