Evaluation of Placental Transfer and Tissue Distribution of cis- and Trans-Permethrin in Pregnant Rats and Fetuses Using a Physiological-Based Pharmacokinetic Model.

Biomonitoring studies have highlighted the exposure of pregnant women to pyrethroids based on the measurement of their metabolites in urine. Pyrethroids can cross the placental barrier and be distributed in the fetus as some pyrethroids were also measured in the meconium of newborns. Prenatal exposure to pyrethroids is suspected to alter the neurodevelopment of children, and animal studies have shown that early life exposure to permethrin, one of the most commonly used pyrethroid in household applications, can alter the brain development. This study aimed to characterize the fetal permethrin exposure throughout gestation in rats. We developed a pregnancy physiologically based pharmacokinetic (pPBPK) model that describes the maternal and fetal kinetics of the cis- and trans- isomers of permethrin during the whole gestation period. Pregnant Sprague-Dawley rats were exposed daily to permethrin (50 mg/kg) by oral route from the start of gestation to day 20. Permethrin isomers were quantified in the feces, kidney, mammary gland, fat, and placenta in dams and in both maternal and fetal blood, brain, and liver. Cis- and trans-permethrin were quantified in fetal blood and tissues, with higher concentrations for the cis-isomer. The pPBPK model was fitted to the toxicokinetic maternal and fetal data in a Bayesian framework. Several parameters were adjusted, such as hepatic clearances, partition coefficients, and intestinal absorption. Our work allowed to estimate the prenatal exposure to permethrin in rats, especially in the fetal brain, and to quantitatively estimate the placental transfer. These transfers could be extrapolated to humans and be incorporated in a human pPBPK model to estimate the fetal exposure to permethrin from biomonitoring data.

Repeated exposure to nanosecond high power pulsed microwaves increases cancer incidence in rat.

High-power microwaves are used to inhibit electronics of threatening military or civilian vehicles. This work aims to assess health hazards of high-power microwaves and helps to define hazard threshold levels of modulated radiofrequency exposures such as those emitted by the first generations of mobile phones. Rats were exposed to the highest possible field levels, under single acute or repetitive exposures for eight weeks. Intense microwave electric fields at 1 MV m-1 of nanoseconds duration were applied from two sources at different carrier frequencies of 10 and 3.7 GHz. The repetition rate was 100 pps, and the duration of train pulses lasted from 10 s to twice 8 min. The effects on the central nervous system were evaluated, by labelling brain inflammation marker GFAP and by performing different behavioural tests: rotarod, T-maze, beam-walking, open-field, and avoidance test. Long-time survival was measured in animals repeatedly exposed, and anatomopathological analysis was performed on animals sacrificed at two years of life or earlier in case of precocious death. Control groups were sham exposed. Few effects were observed on behaviour. With acute exposure, an avoidance reflex was shown at very high thermal level (22 W kg-1); GFAP was increased some days after exposure. Most importantly, with repeated exposures, survival time was 4-months shorter in the exposed group, with eleven animals exhibiting a large sub-cutaneous tumour, compared to two in the sham group. A residual X-ray exposure was also present in the beam (0.8 Gy), which is probably not a bias for the observed result. High power microwaves below thermal level in average, can increase cancer prevalence and decrease survival time in rats, without clear effects on behaviour. The parameters of this effect need to be further explored, and a more precise dosimetry to be performed.

Determination of maternal and foetal distribution of cis- and trans-permethrin isomers and their metabolites in pregnant rats by liquid chromatography tandem mass spectrometry (LC-MS/MS).

We developed a method to quantify cis-permethrin and trans-permethrin and their metabolites in several biological matrices in pregnant rats and foetuses using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The objective was to quantify cis-permethrin and trans-permethrin in faeces, kidney, mammary gland, fat and placenta in mothers and in both maternal and foetal blood, brain and liver. The metabolites cis-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (cis-DCCA), trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (trans-DCCA) and 3-phenoxybenzoic acid (3-PBA) were measured in blood, liver and urine. Sample preparation was performed by liquid-liquid extraction. A purification step was not carried out except for the more complex biological samples (fat, mammary glands and faeces). Validation parameters including specificity, linearity, matrix effect, limits of quantification (LOQs), accuracy and precision were evaluated. The recoveries of target compounds ranged from 47 to 136%. LOQs were in the range 4 to 80 ng/mL for permethrin isomers and 4 to 800 ng/mL for their respective metabolites. Intra- and inter-batch precision and accuracy in matrix were better than 15%. The validated method was applied in a preliminary toxicokinetic study in pregnant rats with oral dosing of 50 mg/kg permethrin. In pregnant rats, permethrin isomers and their metabolites were quantified in all requested matrices except maternal liver and blood for trans-permethrin and cis-DCCA respectively. In foetuses, cis- and trans-permethrin were also quantified, demonstrating that the method is suitable for the analysis of foetal distribution of permethrin in toxicokinetic studies.

Possible effects of radiofrequency electromagnetic fields on in vivo C6 brain tumors in Wistar rats.

PURPOSE: Glioblastoma is a malignant brain tumor which has one of the poorest prognosis. It is not clear if toxic environmental factors can influence its aggressiveness. Recently, it was suggested that brain cancer patients with heavy cell phone use showed reduced survival. Here we aimed to assess the effect of controlled brain averaged specific absorption rate (BASAR) from heavy use of cell phone radiofrequency electromagnetic fields (RF-EMF) on in vivo C6 brain tumors in Wistar rats. METHODS: C6 cells grafted male rats were exposed to GSM 900 MHz signal at environmental BASAR, 0 (sham), 0.25 or 0.5 W/kg (5 days a week, 45 min a day in restraint), or were cage controls (no restraint). At death, tumor volume and immunohistochemistry for CD31, cleaved caspase (CC) 3 and Ki67 were assessed to examine vascularization, apoptosis and cellular divisions, respectively. Moreover, immune cell invasion, necrosis and mitotic index were determined. RESULTS: Results showed no BASAR effect on survival (31 days post-graft median), tumor volume, mitotic index, vascularization, infiltration, necrosis or cell division. However, results suggested a BASAR-dependent reduction of immune cell invasion and apoptosis. CONCLUSIONS: Our data suggested an action of RF-EMF by reducing immune cell invasion and glioblastoma cell apoptosis, at probably too low amplitude to impact survival. Further replication studies are needed to confirm these observations.

Alteration of adaptive behaviors of progeny after maternal mobile phone exposure.

Exposure of pregnant women to radiofrequency (RF) devices raises questions on their possible health consequences for their progeny. We examined the hazard threshold of gestational RF on the progeny's glial homeostasis, sensory-motor gating, emotionality, and novelty seeking and tested whether maternal immune activation would increase RF toxicity. Pregnant dams were daily restrained with loop antennas adjoining the abdomen (fetus body specific absorption rates (SAR): 0, 0.7, or 2.6 W/kg) and received three lipopolysaccharide (LPS) intra-peritoneal injections (0 or 80 µg/kg). Scores in the prepulse startle inhibition, fear conditioning, open field, and elevated plus maze were assessed at adolescence and adulthood. Glial fibrillary acidic protein (GFAP) and interleukines-1ß (ILs) were quantified. LPS induced a SAR-dependent reduction of the prepulse startle inhibition in adults. Activity in the open field was reduced at 2.6 W/kg at adolescence. GFAP and ILs, emotional memory, and anxiety-related behaviors were not modified. These data support the hypothesis that maternal immune activation increased the developmental RF exposure-induced long-term neurobiological impairments. These data support the fact that fetuses who receive combined environmental exposures with RF need special attention for protection.

Study of TiO2 P25 Nanoparticles Genotoxicity on Lung, Blood, and Liver Cells in Lung Overload and Non-Overload Conditions After Repeated Respiratory Exposure in Rats.

Inhaled titanium dioxide (TiO2) nanoparticles (NPs) can have negative health effects, and have been shown to cause respiratory tract cancer in rats. Inflammation has been linked to oxidative stress, and both have been described as possible mechanisms for genotoxicity of NPs, but rarely examined side-by-side in animal studies. In the present study, a wide range of complementary endpoints have been performed to study TiO2 P25 NP-induced genotoxicity in lung overload and non-overload conditions. Additionally, lung burden, inflammation, cytotoxicity and oxidative stress have also been evaluated in order to link genotoxicity with these responses. To assess quick and delayed responses after recovery, endpoints were evaluated at two time points: 2 h and 35 days after three repeated instillations. This study confirmed the previously described lung overload threshold at approximately 200-300 cm2 of lung burden for total particle surface area lung deposition or 4.2 µl/kg for volume-based cumulative lung exposure dose, above which lung clearance is impaired and inflammation is induced. Our results went on to show that these overload doses induced delayed genotoxicity in lung, associated with persistent inflammation only at the highest dose. The lowest tested doses had no toxicity or genotoxicity effects in the lung. In blood, no lymphocyte DNA damage, erythrocytes chromosomal damage or gene mutation could be detected. Our data also demonstrated that only overload doses induced liver DNA lesions irrespective of the recovery time. Tested doses of TiO2 P25 NPs did not induce glutathione changes in lung, blood or liver at both recovery times.

Cerebral radiofrequency exposures during adolescence: Impact on astrocytes and brain functions in healthy and pathologic rat models.

The widespread use of mobile phones by adolescents raises concerns about possible health effects of radiofrequency electromagnetic fields (RF EMF 900 MHz) on the immature brain. Neuro-development is a period of particular sensitivity to repeated environmental challenges such as pro-inflammatory insults. Here, we used rats to assess whether astrocyte reactivity, perception, and emotionality were affected by RF EMF exposures during adolescence. We also investigated if adolescent brains were more sensitive to RF EMF exposures after neurodevelopmental inflammation. To do so, we either performed 80 µg/kg intra-peritoneal injections of lipopolysaccharides during gestation or 1.25 µg/h intra-cerebro-ventricular infusions during adolescence. From postnatal day (P)32 to 62, rats were subjected to 45 min RF EMF exposures to the brain (specific absorption rates: 0, 1.5, or 6 W/kg, 5 days/week). From P56, they were tested for perception of novelty, anxiety-like behaviors, and emotional memory. To assess astrocytic reactivity, Glial Fibrillary Acidic Protein was measured at P64. Our results did not show any neurobiological impairment in healthy and vulnerable RF EMF-exposed rats compared to their sham-exposed controls. These data did not support the hypothesis of a specific cerebral sensitivity to RF EMF of adolescents, even after a neurodevelopmental inflammation. Bioelectromagnetics. 37:338-350, 2016. © 2016 Wiley Periodicals, Inc.

Correction: Effet of Combined Nitrogen Dioxide and Carbon Nanoparticle Exposure on Lung Function During Ovalbumin Sensitization in Brown Norway Rat.

[This corrects the article DOI: 10.1371/journal.pone.0045687.].

Effect of combined nitrogen dioxide and carbon nanoparticle exposure on lung function during ovalbumin sensitization in Brown Norway rat.

The interaction of particulate and gaseous pollutants in their effects on the severity of allergic inflammation and airway responsiveness are not well understood. We assessed the effect of exposure to NO(2) in the presence or absence of repetitive treatment with carbon nanoparticle (CNP) during allergen sensitization and challenges in Brown-Norway (BN) rat, in order to assess their interactions on lung function and airway responses (AR) to allergen and methacholine (MCH), end-expiratory lung volume (EELV), bronchoalveolar lavage fluid (BALF) cellular content, serum and BALF cytokine levels and histological changes. Animals were divided into the following groups (n = 6): Control; CNP (Degussa-FW2): 13 nm, 0.5 mg/kg instilled intratracheally ×3 at 7-day intervals; OVA: ovalbumin-sensitised; OVA+CNP: both sensitized and exposed to CNP. Rats were divided into equal groups exposed either to air or to NO(2), 10 ppm, 6 h/d, 5d/wk for 4 weeks. Exposure to NO(2), significantly enhanced lung inflammation and airway reactivity, with a significantly larger effect in animals sensitized to allergen, which was related to a higher expression of TH1 and TH2-type cytokines. Conversely, exposure to NO(2) in animals undergoing repeated tracheal instillation of CNP alone, increased BALF neutrophilia and enhanced the expression of TH1 cytokines: TNF-α and IFN-γ, but did not show an additive effect on airway reactivity in comparison to NO(2) alone. The exposure to NO(2) combined with CNP treatment and allergen sensitization however, unexpectedly resulted in a significant decrease in both airway reactivity to allergen and to methacholine, and a reduction in TH2-type cytokines compared to allergen sensitization alone. EELV was significantly reduced with sensitization, CNP treatment or both. These data suggest an immunomodulatory effect of repeated tracheal instillation of CNP on the proinflammatory effects of NO(2) exposure in sensitized BN rat. Furthermore, our findings suggest that NO(2), CNP and OVA sensitization may significantly slow overall lung growth in parenchymally mature animals.

Characterization of endocrine-disrupting chemicals based on hormonal balance disruption in male and female adult rats.

Reproductive functions are controlled by a finely tuned balance between estrogens and androgens. To further characterize the gonadal pathways leading to hormonal balance disruption by atrazine, vinclozolin, methoxychlor, and bisphenol A in rat, we investigated their effects in male and female young adult animals. Specifically, we assessed reproductive tract alterations, sex hormone balance in serum and gonads, tissue dosimetry, and mRNA expression. Remarkably, we observed different aromatase regulation profiles between animals with similar estrogen-to-androgen ratios but with different chemical treatments. For example, increased estrogen-to-androgen ratios in atrazine-treated females could be partly linked to aromatase upregulation, while in methoxychlor- and bisphenol A-treated females, peripheral mechanisms such as conjugation/deconjugation processes might be more likely to elevate estrogen levels. In vinclozolin-treated animals, the decreased estrogen-to-androgen ratios reported might be due to an increase of peripheral (adrenal) steroidogenesis. Thus, measurement of many endpoints is necessary for good risk assessment.

Longitudinal 3He and proton imaging of magnetite biodistribution in a rat model of instilled nanoparticles.

Epidemiological and toxicological studies have provided evidence that accidentally inhaled nanosize ultrafine particles can induce chronic or acute health damage. MRI, being noninvasive, is able to assess the biodistribution and clearance of magnetically labeled nanoparticles induced by instillation or inhalation. We report 3He and proton MRI follow-up of lung, liver, spleen, and kidney distribution of USPIO (ultrasmall superparamagnetic iron oxide) in a rat model. The sensitivity of the imaging technique to various concentrations of instilled magnetite suspension was first assessed in vivo (n=12). A 2-week longitudinal imaging study was then performed on animals (n=7) instilled with a 0.5 mg magnetite solution. Hypointense and void signal regions associated with intrapulmonary USPIO were observed in the 3He ventilation images throughout the study, whereas no USPIO-related proton signal intensity changes were found. Intrapulmonary magnetite nanoparticle confinement was confirmed by ex vivo iron assay and histological analysis. This study demonstrates that combined 3He and proton MRI enables noninvasive assessment of the distribution and clearance of magnetically labeled instilled nanoparticles.

Propylene glycol monomethyl ether. A three-generation study of isomer beta effects on reproductive and developmental parameters in rats.

Propylene glycol monomethyl ether (PGME) is widely used as a solvent in numerous commercial products. Its chemical synthesis leads to the formation of two isomers: alpha and beta, the latter being usually present in the range of 0.5-1.5%. Isomer alpha has been shown to be of low toxicity. Isomer beta raises concerns as to its reproductive and developmental effects. We evaluated the reproductive and developmental toxicity of two different commercial mixes of PGME (Mix A: 99% isomer alpha and 0.5% isomer beta, Mix B: 98.5% isomer alpha and 1.5% isomer beta) on Sprague-Dawley rats. The use of two mixes allowed us to differentiate between isomer alpha and isomer beta effects. Male and female rats were exposed through drinking water to mixes A or B during a gametogenesis cycle (64 days for males and 15 days for females) to 0, 2, 5, 10 and 15% (v/v) of each mix. These animals (F0) and the three following generations (F1, F2 and F3) were followed. We observed a statistically significant decrease in the number of pups in isomer alpha-treated animals of generation F1 and a nondose-related variation of the sex ratio in F1 and F2 generations after PGME mix B treatment. The most important effect observed was a decrease in testicular and epididymal sperm counts in relation to PGME isomer beta in acute daily exposure, on the first parental generation. The effect evidenced on sex ratio needs further work in order to assay the potential persistent effects of PGME exposure.

Interference of a short-term exposure to nitrogen dioxide with allergic airways responses to allergenic challenges in BALB/c mice.

Nitrogen dioxide (NO(2)) is a common indoor and outdoor air pollutant whose role in the induction of asthma is unclear. We investigated the effects of NO(2) on the development of asthma-like responses to allergenic challenge in BALB/c mice. Ovalbumin (OVA)-immunized mice were intranasally challenged with OVA or saline solution just before starting a 3 h exposure to 5 or 20 ppm NO(2) or air. Twenty parts per million of NO(2) induced a significant increase of bronchopulmonary hyperreactivity in OVA-challenged mice and of permeability according to the fibronectin content of the bronchoalveolar lavage fluid (BALF) 24 h after exposure, as compared with air or 5 ppm NO(2). Eosinophilia (cell counts in the BALF and eosinophil peroxidase of lung tissue) was detected at 24 and 72 h with similar levels for air and 20 ppm NO(2), whereas a marked reduction was unexpectedly observed for 5 ppm NO(2). At 24 h, interleukin-5 in the BALF was markedly reduced at 5 ppm compared with 20 ppm NO(2) and was also more intense for 20 ppm NO(2) than for the air group. In contrast to specific IgG1 titers, anti-OVA IgE titers and interleukin-4 in the BALF were not affected by NO(2) exposure. Irrespective of the concentration of NO(2), OVA-challenged mice did not develop late mucosal metaplasia compared with those exposed to OVA-air. These results indicate that a short exposure to NO(2) can exacerbate or inhibit some features of the development of allergic disease in mice and may depend on the concentration of pollutant.