Gestational exposure to perfluorooctanoic acid (PFOA): Alterations in motor related behaviors.

Perfluoroalkyl and polyfluoroalkyl substances are used in commercial applications and developmental exposure has been implicated in alterations in neurobehavioral functioning. While associations between developmental perfluorooctanoic acid (PFOA) exposure and human outcomes have been inconsistent, studies in experimental animals suggest alterations in motor related behaviors. To examine a dose-response pattern of neurobehavioral effects following gestational exposure to PFOA, pregnant CD-1 mice received PFOA (0, 0.1, 0.3, 1.0mg/kg/day) via oral gavage from gestational day 1-17 and the male offspring examined. Motor activity assessments on postnatal day (PND)18, 19, and 20 indicated a shift in the developmental pattern with an elevated activity level observed in the 1.0mg/kg/day dose group on PND18. In the adult, no alterations were observed in body weights, activity levels, diurnal pattern of running wheel activity, startle response, or pre-pulse startle inhibition. In response to a subcutaneous injection of saline or nicotine (80µg/kg), all animals displayed a transient increase in activity likely associated with handling with no differences observed across dose groups. Inhibition of motor activity over 18days of 400µg/kg nicotine injection was not significantly different across dose groups. Hyperactivity induced by 2mg/kg (+)-methamphetamine hydrochloride intraperitoneal injection was significantly lower in the 1.0mg/kg/day PFOA dose group as compared to controls. Taken together, these data suggest that the effects on motor-related behaviors with gestational PFOA exposure do not mimic those reported for acute postnatal exposure. Changes were not observed at dose levels under 1.0mg/kg/day PFOA. Further examination of pathways associated with methamphetamine-induced activity is warranted.

Gestational and chronic low-dose PFOA exposures and mammary gland growth and differentiation in three generations of CD-1 mice.

BACKGROUND: Prenatal exposure to perfluorooctanoic acid (PFOA), a ubiquitous industrial surfactant, has been reported to delay mammary gland development in female mouse offspring (F1) and the treated lactating dam (P0) after gestational treatments at 3 and 5 mg PFOA/kg/day. OBJECTIVE: We investigated the consequences of gestational and chronic PFOA exposure on F1 lactational function and subsequent development of F2 offspring. METHODS: We treated P0 dams with 0, 1, or 5 mg PFOA/kg/day on gestation days 1-17. In addition, a second group of P0 dams treated with 0 or 1 mg/kg/day during gestation and their F1 and F2 offspring received continuous PFOA exposure (5 ppb) in drinking water. Resulting adult F1 females were bred to generate F2 offspring, whose development was monitored over postnatal days (PNDs) 1-63. F1 gland function was assessed on PND10 by timed-lactation experiments. Mammary tissue was isolated from P0, F1, and F2 females throughout the study and histologically assessed for age-appropriate development. RESULTS: PFOA-exposed F1 dams exhibited diminished lactational morphology, although F1 maternal behavior and F2 offspring body weights were not significantly affected by P0 treatment. In addition to reduced gland development in F1 females under all exposures, F2 females with chronic low-dose drinking-water exposures exhibited visibly slowed mammary gland differentiation from weaning onward. F2 females derived from 5 mg/kg PFOA-treated P0 dams displayed gland morphology similar to F2 chronic water exposure groups on PNDs 22-63. CONCLUSIONS: Gestational PFOA exposure induced delays in mammary gland development and/or lactational differentiation across three generations. Chronic, low-dose PFOA exposure in drinking water was also sufficient to alter mammary morphological development in mice, at concentrations approximating those found in contaminated human water supplies.

Prenatal perfluorooctanoic acid exposure in CD-1 mice: low-dose developmental effects and internal dosimetry.

Perfluorooctanoic acid (PFOA) is an environmental contaminant that causes adverse developmental effects in laboratory animals. To investigate the low-dose effects of PFOA on offspring, timed-pregnant CD-1 mice were gavage dosed with PFOA for all or half of gestation. In the full-gestation study, mice were administered 0, 0.3, 1.0, and 3.0 mg PFOA/kg body weight (BW)/day from gestation days (GD) 1-17. In the late-gestation study, mice were administered 0, 0.01, 0.1, and 1.0 mg PFOA/kg BW/day from GD 10-17. Exposure to PFOA significantly (p < 0.05) increased offspring relative liver weights in all treatment groups in the full-gestation study and in the 1.0 mg PFOA/kg group in the late-gestation study. In both studies, the offspring of all PFOA-treated dams exhibited significantly stunted mammary epithelial growth as assessed by developmental scoring. At postnatal day 21, mammary glands from the 1.0 mg/kg GD 10-17 group had significantly less longitudinal epithelial growth and fewer terminal end buds compared with controls (p < 0.05). Evaluation of internal dosimetry in offspring revealed that PFOA concentrations remained elevated in liver and serum for up to 6 weeks and that brain concentrations were low and undetectable after 4 weeks. These data indicate that PFOA-induced effects on mammary tissue (1) occur at lower doses than effects on liver weight in CD-1 mice, an observation that may be strain specific, and (2) persist until 12 weeks of age following full-gestational exposure. Due to the low-dose sensitivity of mammary glands to PFOA in CD-1 mice, a no observable adverse effect level for mammary developmental delays was not identified in these studies.

Endocrine disrupting properties of perfluorooctanoic acid.

Perfluoroalkyl acids (PFAAs) have attracted attention in recent years for their environmental ubiquity, as well as their toxicity. Several PFAAs are found in human tissues globally, as humans are exposed on a daily basis through intake of contaminated food, water, and air, irrespective of proximity to industry. Perfluorooctanoic acid (PFOA) is a PFAA shown to be developmentally toxic in mice, with broad and varied health consequences that may include long-lasting effects in reproductive tissues and metabolic reprogramming. To date, the only demonstrated mode of action by which the health effects of PFOA are mediated is via the activation of the peroxisome proliferator-activated receptor alpha (PPARα). The endogenous roles for this receptor, as well as the adverse outcomes of activation by exogenous agents during development, are currently under investigation. Recent studies suggest that PFOA may alter steroid hormone production or act indirectly, via ovarian effects, as a novel means of endocrine disruption. Here we review the existing literature on the known health effects of PFOA in animal models, focusing on sensitive developmental periods. To complement this, we also present epidemiologic health data, with the caveat that these studies largely address only associations between adult exposures and outcomes, rarely focusing on endocrine-specific endpoints, susceptible subpopulations, or windows of sensitivity. Further research in these areas is needed.

An overview of the effects of dioxins and dioxin-like compounds on vertebrates, as documented in human and ecological epidemiology.

Dioxins and dioxin-like compounds are primary examples of persistent organic pollutants that induce toxicity in both wildlife and humans. Over the past 200 years these compounds have been almost exclusively generated by human activity and have left a string of disasters in the wake of their accidental release. Most recently, the contamination of the Irish pork supply with dioxins resulted in an international recall of all Irish pork products. Epidemiologic data on human and ecological dioxin exposures have revealed a common pattern of biological response among vertebrate species, which is mediated through activation of the Aryl hydrocarbon Receptor (AhR). These AhR-mediated effects include profound consequences on the vertebrate individual exposed in early life with respect to myriad developmental endpoints including neurologic, immunologic, and reproductive parameters. Humans appear to be susceptible to these effects in a manner similar to that of the laboratory and wildlife species, which have demonstrated such outcomes. Furthermore, epidemiologic data suggest that there is little or no margin of exposure for humans with respect to these developmental effects. Given these concerns, prudent public health policy should include the continued reduction of exposures.

Phenotypic dichotomy following developmental exposure to perfluorooctanoic acid (PFOA) in female CD-1 mice: Low doses induce elevated serum leptin and insulin, and overweight in mid-life.

The synthetic surfactant, perfluorooctanoic acid (PFOA) is a proven developmental toxicant in mice, causing pregnancy loss, increased neonatal mortality, delayed eye opening, and abnormal mammary gland growth in animals exposed during fetal life. PFOA is found in the sera and tissues of wildlife and humans throughout the world, but is especially high in the sera of children compared to adults. These studies in CD-1 mice aim to determine the latent health effects of PFOA following: (1) an in utero exposure, (2) an in utero exposure followed by ovariectomy (ovx), or (3) exposure as an adult. Mice were exposed to 0, 0.01, 0.1, 0.3, 1, 3, or 5mg PFOA/kg BW for 17 days of pregnancy or as young adults. Body weight was reduced in the highest doses on postnatal day (PND) 1 and at weaning. However, the lowest exposures (0.01-0.3mg/kg) significantly increased body weight, and serum insulin and leptin (0.01-0.1mg/kg) in mid-life after developmental exposure. PFOA exposure combined with ovx caused no additional increase in mid-life body weight. At 18 months of age, the effects of in utero PFOA exposure on body weight were no longer detected. White adipose tissue and spleen weights were decreased at high doses of PFOA in intact developmentally exposed mice, and spleen weight was reduced in PFOA-exposed ovx mice. Brown adipose tissue weight was significantly increased in both ovx and intact mice at high PFOA doses. Liver weight was unaffected in late life by these exposure paradigms. Finally, there was no effect of adult exposure to PFOA on body weight. These studies demonstrate an important window of exposure for low-dose effects of PFOA on body weight gain, as well as leptin and insulin concentrations in mid-life, at a lowest observed effect level of 0.01mg PFOA/kg BW. The mode of action of these effects and its relevance to human health remain to be explored.

Analysis of PFOA in dosed CD-1 mice. Part 2. Disposition of PFOA in tissues and fluids from pregnant and lactating mice and their pups.

Previous studies in mice with multiple gestational exposures to perfluorooctanoic acid (PFOA) demonstrate numerous dose dependent growth and developmental effects which appeared to worsen if offspring exposed in utero nursed from PFOA-exposed dams. To evaluate the disposition of PFOA in the pregnant and lactating dam and her offspring, time-pregnant CD-1 mice received a single 0, 0.1, 1, or 5mg PFOA/kg BW dose (n=25/dose group) by gavage on gestation day 17. Maternal and pup fluids and tissues were collected over time. Pups exhibited significantly higher serum PFOA concentrations than their respective dams, and their body burden increased after birth until at least postnatal day 8, regardless of dose. The distribution of milk:serum PFOA varied by dose and time, but was typically in excess of 0.20. These data suggest that milk is a substantial PFOA exposure route in mice and should be considered in risk assessment modeling designs for this compound.

Effects of perfluorooctanoic acid on mouse mammary gland development and differentiation resulting from cross-foster and restricted gestational exposures.

The adverse consequences of developmental exposures to perfluorooctanoic acid (PFOA) are established in mice, and include impaired development of the mammary gland (MG). However, the relationships between timing or route of exposure, and consequences in the MG have not been characterized. To address the effects of these variables on the onset and persistence of MG effects in female offspring, timed pregnant CD-1 dams received PFOA by oral gavage over various gestational durations. Cross-fostering studies identified the 5mg/kg dose, under either lactational- or intrauterine-only exposures, to delay MG development as early as postnatal day (PND) 1, persisting beyond PND 63. Intrauterine exposure during the final days of pregnancy caused adverse MG developmental effects similar to that of extended gestational exposures. These studies confirm a window of MG sensitivity in late fetal and early neonatal life, and demonstrate developmental PFOA exposure results in early and persistent MG effects, suggesting permanent consequences.

Developmental toxicity of perfluorooctanoic acid in the CD-1 mouse after cross-foster and restricted gestational exposures.

Perfluorooctanoic acid (PFOA) is a persistent pollutant and is detectable in human serum (5 ng/ml in the general population of the Unites States). PFOA is used in the production of fluoropolymers which have applications in the manufacture of a variety of industrial and commercial products (e.g., textiles, house wares, electronics). PFOA is developmentally toxic and in mice affects growth, development, and viability of offspring. This study segregates the contributions of gestational and lactational exposures and considers the impact of restricting exposure to specific gestational periods. Pregnant CD-1 mice were dosed on gestation days (GD) 1-17 with 0, 3, or 5 mg PFOA/kg body weight, and pups were fostered at birth to give seven treatment groups: unexposed controls, pups exposed in utero (3U and 5U), lactationally (3L and 5L), or in utero + lactationally (3U + L and 5U + L). In the restricted exposure (RE) study, pregnant mice received 5 mg PFOA/kg from GD7-17, 10-17, 13-17, or 15-17 or 20 mg on GD15-17. In all PFOA-treated groups, dam weight gain, number of implantations, and live litter size were not adversely affected and relative liver weight increased. Treatment with 5 mg/kg on GD1-17 increased the incidence of whole litter loss and pups in surviving litters had reduced birth weights, but effects on pup survival from birth to weaning were only affected in 5U + L litters. In utero exposure (5U), in the absence of lactational exposure, was sufficient to produce postnatal body weight deficits and developmental delay in the pups. In the RE study, birth weight and survival were reduced by 20 mg/kg on GD15-17. Birth weight was also reduced by 5 mg/kg on GD7-17 and 10-17. Although all PFOA-exposed pups had deficits in postnatal weight gain, only those exposed on GD7-17 and 10-17 also showed developmental delay in eye opening and hair growth. In conclusion, the postnatal developmental effects of PFOA are due to gestational exposure. Exposure earlier in gestation produced stronger responses, but further study is needed to determine if this is a function of higher total dose or if there is a developmentally sensitive period.

Gestational PFOA exposure of mice is associated with altered mammary gland development in dams and female offspring.

Perfluorooctanoic acid (PFOA), with diverse and widespread commercial and industrial applications, has been detected in human and wildlife sera. Previous mouse studies linked prenatal PFOA exposure to decreased neonatal body weights (BWs) and survival in a dose-dependent manner. To determine whether effects were linked to gestational time of exposure or to subsequent lactational changes, timed-pregnant CD-1 mice were orally dosed with 5 mg PFOA/kg on gestation days (GD) 1-17, 8-17, 12-17, or vehicle on GD 1-17. PFOA exposure had no effect on maternal weight gain or number of live pups born. Mean pup BWs on postnatal day (PND) 1 in all PFOA-exposed groups were significantly reduced and decrements persisted until weaning. Mammary glands from lactating dams and female pups on PND 10 and 20 were scored based on differentiation or developmental stages. A significant reduction in mammary differentiation among dams exposed GD 1-17 or 8-17 was evident on PND 10. On PND 20, delays in normal epithelial involution and alterations in milk protein gene expression were observed. All exposed female pups displayed stunted mammary epithelial branching and growth at PND 10 and 20. While control litters at PND 10 and 20 had average scores of 3.1 and 3.3, respectively, all treated litters had scores of 1.7 or less, with no progression of duct epithelial growth evident over time. BW was an insignificant covariate for these effects. These findings suggest that in addition to gestational exposure, abnormal lactational development of dams may play a role in early growth retardation of developmentally exposed offspring.