RESUMO
The "4.2 ka event" is a commonly described abrupt climate excursion that occurred about 4200 years ago. However, the extent to which this event is coherent across regional and larger scales is unclear. To objectively assess climate excursions in the Holocene we compile 1142 paleoclimate datasets that span all continents and oceans and include a wide variety of archive and proxy types. We analyze these data to determine the timing, significance and spatial imprint of climate excursions using an objective method that quantifies local, regional and global significance. Site-level excursions in temperature and hydroclimate are common throughout the Holocene, but significant global-scale excursions are rare. The most prominent excursion occurred 8200 years ago, when cold and dry conditions formed a large, significant excursion centered in the North Atlantic. We find additional significant excursions between 1600 and 1000 years ago, which agree with tree-ring data and annual-scale paleoclimate reconstructions, adding confidence and context to our findings. In contrast, although some datasets show significant climate excursions 4200 years ago, they do not occur in large, coherent spatial regions. Consequently, like most other periods in the Holocene, the "4.2 ka event" is not a globally significant climate excursion.
RESUMO
Toothpicks are commonly used but rarely ingested. Unlike most foreign bodies, if accidentally swallowed these rarely spontaneously pass. The duodenum has been reported as the most common site of toothpick foreign body lodgement in the upper gastrointestinal tract. We report the case of a 57-year-old presenting with recurrent urosepsis after non recognition of a toothpick impaction in the duodenum with fistulisation into the right renal pelvis. Endoscopic removal of the foreign body was successful in management of the urosepsis.
RESUMO
Embryonic zebrafish represent a useful test system to screen substances for their ability to perturb development. The exposure scenarios, endpoints captured, and data analysis vary among the laboratories who conduct screening. A lack of harmonization impedes the comparison of the substance potency and toxicity outcomes across laboratories and may hinder the broader adoption of this model for regulatory use. The Systematic Evaluation of the Application of Zebrafish in Toxicology (SEAZIT) initiative was developed to investigate the sources of variability in toxicity testing. This initiative involved an interlaboratory study to determine whether experimental parameters altered the developmental toxicity of a set of 42 substances (3 tested in duplicate) in three diverse laboratories. An initial dose-range-finding study using in-house protocols was followed by a definitive study using four experimental conditions: chorion-on and chorion-off using both static and static renewal exposures. We observed reasonable agreement across the three laboratories as 33 of 42 test substances (78.6%) had the same activity call. However, the differences in potency seen using variable in-house protocols emphasizes the importance of harmonization of the exposure variables under evaluation in the second phase of this study. The outcome of the Def will facilitate future practical discussions on harmonization within the zebrafish research community.
RESUMO
AIM: Peritoneal dissemination of infiltrative appendiceal tumors is a rare and poorly understood phenomenon. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is a well-recognized treatment option for selected patients. Neoadjuvant systemic chemotherapy (NAC) has been shown to be associated with improved overall survival (OS) in colorectal peritoneal metastases but little is known of the impact of this from an appendiceal adenocarcinoma perspective. METHOD: A prospective database of 294 patients with advanced appendiceal primary tumors undergoing CRS ± HIPEC between June 2009 and December 2020 was reviewed. Baseline characteristics and long-term outcomes were compared between patients with adenocarcinoma who received neoadjuvant chemotherapy or upfront surgery. RESULTS: Eighty-six (29%) patients were histologically diagnosed with an appendiceal cancer. These included intestinal-type adenocarcinoma (11.6%), mucinous adenocarcinoma (43%), and goblet cell adenocarcinoma (GCA) or signet ring cell adenocarcinoma (SRCA) (45.4%). Twenty-five (29%) of these underwent NAC, of which eight (32%) exhibited some degree of radiological response. There was no statistical difference in OS at 3 years between the NAC and upfront surgery groups (47.3% vs. 75.8%, p = 0.372). Appendiceal histology subtypes, particularly GCA and SRCA (p = 0.039) and peritoneal carcinomatosis index >10 (p = 0.009), were factors independently associated with worse OS. CONCLUSION: Administration of NAC did not appear to prolong OS in the operative management of disseminated appendiceal adenocarcinomas. GCA and SRCA subtypes display a more aggressive biological phenotype.
Assuntos
Adenocarcinoma , Neoplasias do Apêndice , Carcinoma de Células em Anel de Sinete , Hipertermia Induzida , Neoplasias Peritoneais , Humanos , Neoplasias do Apêndice/tratamento farmacológico , Neoplasias do Apêndice/patologia , Quimioterapia Intraperitoneal Hipertérmica , Terapia Neoadjuvante , Procedimentos Cirúrgicos de Citorredução , Neoplasias Peritoneais/tratamento farmacológico , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/patologia , Carcinoma de Células em Anel de Sinete/tratamento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Taxa de Sobrevida , Estudos Retrospectivos , Terapia CombinadaRESUMO
Sodium metavanadate (NaVO3 ) is a pentavalent vanadium compound used in the metal industry and dietary supplements; human exposure occurs through inhalation of fumes and dust and ingestion of NaVO3 -containing products. The objective of this study was to assess the potential immunotoxicity of NaVO3 . Female B6C3F1/N mice were exposed to 0-500 ppm NaVO3 in drinking water for 28 days and evaluated for effects on immune cell populations and innate, cellular-mediated, and humoral-mediated immunity. There was a decreasing trend in body weight (BW) and BW gain in NaVO3 exposed mice, with a decrease (p ≤ 0.05) in BW gain at ≥250 ppm, relative to control. Conversely, increasing trends in spleen weights and an increase (p ≤ 0.05) in the spleen:BW ratio at ≥250 ppm NaVO3 were observed. NaVO3 exposure altered antibody production against sheep red blood cells (SRBC). Antibody forming cells (AFC)/106 spleen cells exhibited a decreasing trend, with a decrease (p ≤ 0.05) at 500 ppm NaVO3 , concurrent with an increase in percent B cells. NaVO3 had no effect on the serum anti-SRBC IgM antibody titers or anti-keyhole limpet hemocyanin antibody production. Exposure to NaVO3 decreased the percentage of natural killer cells at all dose levels (p ≤ 0.05), with no effect on the lytic activity. NaVO3 altered T-cell populations at 500 ppm but had no effect on T-cell proliferative responses or the lytic activity of cytotoxic T cells. Collectively, these data indicate that NaVO3 exposure can adversely affect the immune system by inducing alterations in humoral-mediated immunity, specifically the AFC response, with no effect on cell-mediated or innate immunity.
Assuntos
Água Potável , Camundongos , Feminino , Humanos , Animais , Ovinos , Vanadatos/toxicidade , Camundongos Endogâmicos , Baço , SódioRESUMO
BACKGROUND: Exposure to asbestos is associated with malignant and nonmalignant respiratory disease. To strengthen the scientific basis for risk assessment on fibers, the National Institute of Environmental Health Sciences (NIEHS) has initiated a series of studies to address fundamental questions on the toxicology of naturally occurring asbestos and related mineral fibers after inhalation exposure. A prototype nose-only exposure system was previously developed and validated. The prototype system was expanded to a large-scale exposure system in this study for conducting subsequent in vivo rodent inhalation studies of Libby amphibole (LA) 2007, selected as a model fiber. RESULTS: The exposure system consisting of six exposure carousels was able to independently deliver stable LA 2007 aerosol to individual carousels at target concentrations of 0 (control group), 0.1, 0.3, 1, 3, or 10 mg/m3. A single aerosol generator was used to provide aerosol to all carousels to ensure that exposure atmospheres were chemically and physically similar, with aerosol concentration as the only major variable among the carousels. Transmission electron microscopy (TEM) coupled with energy dispersive spectrometry (EDS) and selected area electron diffraction (SAED) analysis of aerosol samples collected at the exposure ports indicated the fiber dimensions, chemical composition, and mineralogy were equivalent across exposure carousels and were comparable to the bulk LA 2007 material. CONCLUSION: The exposure system developed is ready for use in conducting nose-only inhalation toxicity studies of LA 2007 in rats. The exposure system is anticipated to have applicability for the inhalation toxicity evaluation of other natural mineral fibers of concern.
Assuntos
Amiantos Anfibólicos , Amianto , Ratos , Animais , Amiantos Anfibólicos/toxicidade , Fibras Minerais , Aerossóis , Exposição por Inalação/efeitos adversosRESUMO
BACKGROUND: Asbestos has been classified as a human carcinogen, and exposure may increase the risk of diseases associated with impaired respiratory function. As the range of health effects and airborne concentrations that result in health effects across asbestos-related natural mineral fiber types are not fully understood, the National Institute of Environmental Health Sciences has established a series of research studies to characterize hazards of natural mineral fibers after inhalation exposure. This paper presents the method development work of this research project. RESULTS: A prototype nose-only exposure system was fabricated to explore the feasibility of generating natural mineral fiber aerosol for in vivo inhalation toxicity studies. The prototype system consisted of a slide bar aerosol generator, a distribution/delivery system and an exposure carousel. Characterization tests conducted using Libby Amphibole 2007 (LA 2007) demonstrated the prototype system delivered stable and controllable aerosol concentration to the exposure carousel. Transmission electron microscopy (TEM) analysis of aerosol samples collected at the exposure port showed the average fiber length and width were comparable to the bulk LA 2007. TEM coupled with energy dispersive spectrometry (EDS) and selected area electron diffraction (SAED) analysis further confirmed fibers from the aerosol samples were consistent with the bulk LA 2007 chemically and physically. CONCLUSIONS: Characterization of the prototype system demonstrated feasibility of generating LA 2007 fiber aerosols appropriate for in vivo inhalation toxicity studies. The methods developed in this study are suitable to apply to a multiple-carousel exposure system for a rat inhalation toxicity testing using LA 2007.
Assuntos
Amiantos Anfibólicos , Amianto , Humanos , Ratos , Animais , Amiantos Anfibólicos/toxicidade , Fibras Minerais , Amianto/análise , Carcinógenos/toxicidade , AerossóisRESUMO
Thallium is a heavy metal that is known to induce a broad spectrum of adverse health effects in humans including alopecia, neurotoxicity, and mortality following high dose acute poisoning events. Widespread human exposure to thallium may occur via consumption of contaminated drinking water; limited toxicity data are available to evaluate the corresponding public health risk. To address this data gap, the Division of Translational Toxicology conducted short-term toxicity studies of a monovalent thallium salt, thallium (I) sulfate. Thallium (I) sulfate was administered via dosed drinking water to time-mated Sprague Dawley (Hsd:Sprague Dawley® SD®) rats (F0 dams) and their offspring (F1) from gestation day (GD) 6 until up to postnatal day (PND) 28 at concentrations of 0, 3.13, 6.25, 12.5, 25, or 50 mg/L, and adult male and female B6C3F1/N mice for up to 2 weeks at concentrations of 0, 6.25, 12.5, 25, 50, or 100 mg/L. Rat dams in the 50 mg/L exposure group were removed during gestation, and dams and offspring in the 25 mg/L exposure group were removed on or before PND 0 due to overt toxicity. Exposure to thallium (I) sulfate at concentrations ≤ 12.5 mg/L did not impact F0 dam body weights, maintenance of pregnancy, littering parameters, or F1 survival (PND 4-28). However, in F1 pups, exposure to 12.5 mg/L thallium (I) sulfate resulted in decreased body weight gains relative to control rats and onset of whole-body alopecia. Measurement of thallium concentrations in dam plasma, amniotic fluid, fetuses (GD 18), and pup plasma (PND 4) indicated marked maternal transfer of thallium to offspring during gestation and lactation. Mice exposed to 100 mg/L thallium (I) sulfate were removed early due to overt toxicity, and mice exposed to ≥ 25 mg/L exhibited exposure concentration-related decreases in body weight. Lowest-observed-effect levels of 12.5 mg/L (rats) and 25 mg/L (mice) were determined based on the increased incidence of clinical signs of alopecia in F1 rat pups and significantly decreased body weights for both rats and mice.
RESUMO
The embryonic zebrafish is a useful vertebrate model for assessing the effects of substances on growth and development. However, cross-laboratory developmental toxicity outcomes can vary and reported developmental defects in zebrafish may not be directly comparable between laboratories. To address these limitations for gaining broader adoption of the zebrafish model for toxicological screening, we established the Systematic Evaluation of the Application of Zebrafish in Toxicology (SEAZIT) program to investigate how experimental protocol differences can influence chemical-mediated effects on developmental toxicity (i.e., mortality and the incidence of altered phenotypes). As part of SEAZIT, three laboratories were provided a common and blinded dataset (42 substances) to evaluate substance-mediated effects on developmental toxicity in the embryonic zebrafish model. To facilitate cross-laboratory comparisons, all the raw experimental data were collected, stored in a relational database, and analyzed with a uniform data analysis pipeline. Due to variances in laboratory-specific terminology for altered phenotypes, we utilized ontology terms available from the Ontology Lookup Service (OLS) for Zebrafish Phenotype to enable additional cross-laboratory comparisons. In this manuscript, we utilized data from the first phase of screening (dose range finding, DRF) to highlight the methodology associated with the development of the database and data analysis pipeline, as well as zebrafish phenotype ontology mapping.
RESUMO
Intermittent fasting (IF) is an established intervention to treat the growing obesity epidemic. However, the interaction between dietary interventions and sex remains a significant knowledge gap. In this study, we use unbiased proteome analysis to identify diet-sex interactions. We report sexual dimorphism in response to intermittent fasting within lipid and cholesterol metabolism and, unexpectedly, in type I interferon signaling, which was strongly induced in females. We verify that secretion of type I interferon is required for the IF response in females. Gonadectomy differentially alters the every-other-day fasting (EODF) response and demonstrates that sex hormone signaling can either suppress or enhance the interferon response to IF. IF fails to potentiate a stronger innate immune response when IF-treated animals were challenged with a viral mimetic. Lastly, the IF response changes with genotype and environment. These data reveal an interesting interaction between diet, sex, and the innate immune system.
Assuntos
Interferon Tipo I , Feminino , Camundongos , Animais , Interação Gene-Ambiente , Hormônios Esteroides Gonadais , Jejum , Dieta , Caracteres SexuaisRESUMO
Two organophosphate esters used as flame retardants and plasticizers, triphenyl phosphate (TPHP) and isopropylated phenyl phosphate (IPP), have been detected in environmental samples around the world. Human exposure primarily occurs via oral ingestion with reported higher concentrations in children. Currently, there are no data to evaluate potential risk from exposure to either TPHP or IPP during fetal development. These short-term perinatal studies in rats provide preliminary toxicity data for TPHP and IPP, including information on transfer to fetus/offspring and across the pup blood-brain barrier. In separate experiments, TPHP or IPP were administered via dosed feed at concentrations 0, 1000, 3000, 10â000, 15â000, or 30â000 ppm to time-mated Hsd:Sprague Dawley SD rats from gestation day (GD) 6 through postnatal day (PND) 28; offspring were provided dosed feed at the same concentration as their dam (PND 28-PND 56). TPHP- and IPP-related toxicity resulted in removal of both 30â000 ppm groups on GD 12 and 15â000 ppm IPP group after parturition. Body weight and organ weights were impacted with exposure in remaining dams. Reproductive performance was perturbed at ≥10â000 ppm TPHP and all IPP exposure groups. In offspring, both TPHP- and IPP-related toxicity was noted in pups at ≥10â000 ppm as well as reduction in bodyweights, delays in pubertal endpoints, and/or reduced cholinesterase enzyme activity starting at 1000 ppm TPHP or IPP. Preliminary internal dose assessment indicated gestational and lactational transfer following exposure to TPHP or IPP. These findings demonstrate that offspring development is sensitive to 1000 ppm TPHP or IPP exposure.
Assuntos
Retardadores de Chama , Gravidez , Feminino , Criança , Ratos , Animais , Humanos , Ratos Sprague-Dawley , Retardadores de Chama/toxicidade , Plastificantes/toxicidade , Organofosfatos/toxicidade , Fosfatos , Ésteres/toxicidadeAssuntos
Cobalto , Tungstênio , Ligas/toxicidade , Antimônio/toxicidade , Cobalto/toxicidade , Humanos , Tungstênio/toxicidadeRESUMO
Vanadium is a ubiquitous environmental contaminant although there are limited data to assess potential adverse human health impact following oral exposure. In support of studies investigating the subchronic toxicity of vanadyl sulfate (V4+) and sodium metavanadate (V5+) following perinatal exposure via drinking water in male and female rats, we have determined the internal exposure and urinary excretion of total vanadium at the end of study. Water consumption decreased with increasing exposure concentration following exposure to both compounds. Plasma and urine vanadium concentration normalized to total vanadium consumed per day increased with the exposure concentration of vanadyl sulfate and sodium metavanadate suggesting absorption increased as the exposure concentration increased. Additionally, females had higher concentrations than males (in plasma only for vanadyl sulfate exposure). Animals exposed to sodium metavanadate had up to 3-fold higher vanadium concentration in plasma and urine compared to vanadyl sulfate exposed animals, when normalized to total vanadium consumed per day, demonstrating differential absorption, distribution, metabolism, and excretion properties between V5+ and V4+ compounds. These data will aid in the interpretation of animal toxicity data of V4+ and V5+ compounds and determine the relevance of animal toxicity findings to human exposures.
Assuntos
Água Potável , Vanádio , Animais , Feminino , Masculino , Ratos , Sódio , Vanadatos/toxicidade , Vanádio/toxicidade , Vanádio/urina , Compostos de VanádioRESUMO
OBJECTIVE: Ethyltoluenes are isolated during crude oil refinement for use in gasoline and commercial products and are ubiquitous in the environment. However, minimal toxicity data are available. Previously, we identified 2-ethyltoluene (2-ET) as the most potent isomer via nose-only inhalation exposure in rodents. Here, we expanded the hazard characterization of 2-ET in two rodent models using whole-body inhalation exposure and evaluated the role of prenatal exposure. METHODS: Time-mated Hsd:Sprague Dawley® SD® rats were exposed to 0, 150, 300, 600, 900, or 1200 ppm 2-ET via inhalation starting on gestation day 6 until parturition. Rat offspring (n = 8/exposure/sex) were exposed to the same concentrations as the respective dams for 2 weeks after weaning. Adult male and female B6C3F1/N mice (n = 5/exposure/sex) were exposed to the same concentrations for 2 weeks. RESULTS AND DISCUSSION: Exposure to ≥600 ppm 2-ET produced acute toxicity in rats and mice characterized by large decreases in survival, body weight, adverse clinical observations, and diffuse nasal olfactory epithelium degeneration (rats) or necrosis (mice). Due to the early removal of groups ≥600 ppm, most endpoint evaluations focused on lower exposure groups. In 150 and 300 ppm exposure groups, reproductive performance and littering were not significantly changed and body weights in exposed rats and mice were 9-18% lower than controls. Atrophy of the olfactory epithelium and nerves was observed in all animals exposed to 150 and 300 ppm. These lesions were more severe in mice than in rats. CONCLUSION: Nasal lesions were observed in all animals after whole-body exposure up to 600 ppm 2-ET for 2 weeks. Future studies should focus on 2-ET metabolism and distribution to better understand species differences and refine hazard characterization of this understudied environmental contaminant.
Assuntos
Exposição por Inalação , Administração por Inalação , Animais , Feminino , Exposição por Inalação/efeitos adversos , Masculino , Camundongos , Camundongos Endogâmicos , Gravidez , Ratos , Ratos Endogâmicos F344 , Ratos Sprague-DawleyRESUMO
The impacts of human-induced environmental change that characterize the Anthropocene are not felt equally across the globe. In the tropics, the potential for the sudden collapse of ecosystems in response to multiple interacting pressures has been of increasing concern in ecological and conservation research. The tropical ecosystems of Papua New Guinea are areas of diverse rainforest flora and fauna, inhabited by human populations that are equally diverse, both culturally and linguistically. These people and the ecosystems they rely on are being put under increasing pressure from mineral resource extraction, population growth, land clearing, invasive species, and novel pollutants. This study details the last â¼90 y of impacts on ecosystem dynamics in one of the most biologically diverse, yet poorly understood, tropical wetland ecosystems of the region. The lake is listed as a Ramsar wetland of international importance, yet, since initial European contact in the 1930s and the opening of mineral resource extraction facilities in the 1990s, there has been a dramatic increase in deforestation and an influx of people to the area. Using multiproxy paleoenvironmental records from lake sediments, we show how these anthropogenic impacts have transformed Lake Kutubu. The recent collapse of algal communities represents an ecological tipping point that is likely to have ongoing repercussions for this important wetland's ecosystems. We argue that the incorporation of an adequate historical perspective into models for wetland management and conservation is critical in understanding how to mitigate the impacts of ecological catastrophes such as biodiversity loss.
Assuntos
Efeitos Antropogênicos , Áreas Alagadas , Mudança Climática , Conservação dos Recursos Naturais , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Humanos , Papua Nova GuinéRESUMO
Termination of pregnancy (TOP) is considered an important component of sexual and reproductive health internationally, but there are known barriers in Australia and countries worldwide. This study investigated the issues for GPs regarding aiding access to TOP and providing early medical abortion (EMA) services for Tasmanian women. Specifically, the aims of the study were to identify the knowledge and attitudes of Tasmanian GPs regarding TOP services and to determine which known barriers to providing EMA are most significant for GPs in Tasmania, Australia. A survey was developed and piloted based on previous qualitative research that identified known barriers to accessing TOP. Surveys were posted to all identified GPs in Tasmania with a reply-paid envelope. In all, 211 (27.4%) responses were returned. GPs identified difficulty accessing TOP services, particularly for rural women and those on a low income. Almost half the GPs, excluding conscientious objectors, indicated they would be interested in providing EMA services, but perceived barriers were significant. The most significant barriers related to accessing appropriate training and support. There was uncertainty around financial reward, support services, medical indemnity and access to the medical abortifacient medications mifepristone and misoprostol. In conclusion, accessing TOP remains an issue for Tasmanian women. Many Tasmanian GPs are interested in providing EMA services if barriers are addressed, but there is a lack of knowledge about the practicalities of implementing EMA. Providing practical support to GPs and increasing knowledge pertaining to EMA provision in general practice could improve access in primary care.
Assuntos
Aborto Induzido , Acessibilidade aos Serviços de Saúde , Feminino , Humanos , Gravidez , Atenção Primária à Saúde , População Rural , TasmâniaRESUMO
Vanadium is a ubiquitous environmental contaminant that exists in multiple oxidation states. Humans are exposed to vanadyl (V4+) and vanadate (V5+) from dietary supplements, food, and drinking water and hence there is a concern for adverse human health. The current investigation is aimed at identifying vanadium oxidation states in vitro and in vivo and internal concentrations following exposure of rats to vanadyl sulfate (V4+) or sodium metavanadate (V5+) via drinking water for 14 d. Investigations in simulated gastric and intestinal fluids showed that V4+ was stable in gastric fluid while V5+ was stable in intestinal fluid. Analysis of rodent plasma showed that the only vanadium present was V4+, regardless of the exposed compound suggesting conversion of V5+ to V4+ in vivo and/or instability of V5+ species in biological matrices. Plasma, blood, and liver concentrations of total vanadium, after normalizing for vanadium dose consumed, were higher in male and female rats following exposure to V5+ than to V4+. Following exposure to either V4+ or V5+, the total vanadium concentration in plasma was 2- to 3-fold higher than in blood suggesting plasma as a better matrix than blood for measuring vanadium in future work. Liver to blood ratios were 4-7 demonstrating significant tissue retention following exposure to both compounds. In conclusion, these data point to potential differences in absorption and disposition properties of V4+ and V5+ salts and may explain the higher sensitivity in rats following drinking water exposure to V5+ than V4+ and highlights the importance of internal dose determination in toxicology studies.
Assuntos
Vanadatos/farmacocinética , Compostos de Vanádio/farmacocinética , Administração Oral , Animais , Carga Corporal (Radioterapia) , Água Potável , Feminino , Suco Gástrico/química , Absorção Gastrointestinal , Secreções Intestinais/química , Fígado/metabolismo , Masculino , Oxirredução , Ratos Sprague-Dawley , Distribuição Tecidual , Toxicocinética , Vanadatos/administração & dosagem , Vanadatos/sangue , Vanadatos/toxicidade , Compostos de Vanádio/administração & dosagem , Compostos de Vanádio/sangue , Compostos de Vanádio/toxicidadeRESUMO
2,2'-Dimorpholinodiethyl ether (DMDEE) is a specialty amine catalyst used in the production of flexible foams, adhesives and coatings. The potential for occupational exposure to DMDEE is high, but toxicity data are very limited. The objective of this work was to develop a method to quantitate DMDEE in biological matrices to assess gestational and lactational transfer of DMDEE in rats following exposure of dams The method used protein precipitation, followed by removal of phospholipids and analysis of supernatant by ultra-performance liquid chromatography-tandem mass spectrometry. Rat fetuses were homogenized in water prior to protein precipitation and delipidation procedures. The method was evaluated in male Sprague Dawley rat plasma over the concentration range 5 to 1000 ng/mL. The method was linear (r ≥ 0.99), accurate (mean relative error (RE) ≤ ±11.9%) and precise (relative standard deviation (RSD) ≤ 2.7%). The mean absolute recovery was 106%. The limit of detection was 0.262 ng/mL. Standards as high as â¼100,000 ng/mL could be successfully diluted into the calibration range (mean %RE = -14.9; %RSD = 0.5). The method was evaluated in Sprague Dawley rat dam plasma, post-natal day 4 pup plasma, gestational day (GD) 18 amniotic fluid and fetal homogenate (mean %RE ≤ ±11.9; %RSD ≤ 2.3). Concentrations of DMDEE in rat dam plasma, amniotic fluid and fetal homogenate stored for at least 29 days and in pup plasma for at least 18 days at -80°C were within 87.7 to 99.5% of Day 0 concentrations, demonstrating that DMDEE is stable in these matrices. The method was used to quantitate DMDEE in rat plasma, amniotic fluid and fetus samples from a dose range finding toxicology study in which dams were dosed via gavage with DMDEE from GD 6 at doses of 0 (control), 62.5 and 250 mg/kg/day. DMDEE concentration increased with the dose in all matrices examined. The concentration in GD 18 fetuses was almost 2-fold higher than GD 18 dams demonstrating gestational transfer of DMDEE. However, the concentration in post-natal day 4 pup plasma was more than an order of magnitude lower than corresponding dam plasma suggesting less potential for transfer of DMDEE from dams to pups via lactation. There was no significant difference in concentration for male and female pup plasma.