Research Topics
| K M CroftonSummaryAffiliation: U.S. Environmental Protection Agency Country: USA Publications
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Detail Information
Publications
Low-frequency hearing loss following perinatal exposure to 3,3',4,4',5-pentachlorobiphenyl (PCB 126) in ratsK M Crofton
Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, U S Environmental Protection Agency, Research Triangle Park, NC 27711, USA
Neurotoxicol Teratol 21:299-301. 1999..These results are important in that the data implicate, at least partially, the coplanar PCBs in the developmental ototoxicity induced by Aroclor 1254...- Mode of action: neurotoxicity induced by thyroid hormone disruption during development--hearing loss resulting from exposure to PHAHsKevin M Crofton
US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
Crit Rev Toxicol 35:757-69. 2005..Research on these areas of uncertainty will increase confidence that this MOA for PCBs is not likely to not occur in humans, assuming normal conditions of limited ambient exposure... 
Developmental neurotoxicity testing: a path forwardKevin M Crofton
Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
Congenit Anom (Kyoto) 52:140-6. 2012....
Transcriptional response of rat frontal cortex following acute in vivo exposure to the pyrethroid insecticides permethrin and deltamethrinJoshua A Harrill
Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
BMC Genomics 9:546. 2008..The purpose of this study was to characterize and explore changes in gene expression that occur in the rat frontal cortex, an area of CNS affected by pyrethroids, following an acute low-dose exposure...- A qualitative retrospective analysis of positive control data in developmental neurotoxicity studiesK M Crofton
Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, ORD, MD B105 04, U S Environmental Protection Agency, Research Triangle Park, NC 27711, USA
Neurotoxicol Teratol 26:345-52. 2004..Adequate positive control data are very useful in a weight-of-evidence approach to help determine the biological significance of results, and also to increase the confidence in negative results from DNT studies... - Developmental disruption of thyroid hormone: correlations with hearing dysfunction in ratsK M Crofton
Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U S EPA, Research Triangle Park, NC 27711, USA
Risk Anal 24:1665-71. 2004..This correlation suggests that T4 serum concentrations at 14 or 21 days of postnatal age may be a good predictive biomarker in rodents of the adverse consequence of developmental exposure to TDCs... 
Thyroid-hormone-disrupting chemicals: evidence for dose-dependent additivity or synergismKevin M Crofton
Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U S Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
Environ Health Perspect 113:1549-54. 2005..The results imply that cumulative risk approaches be considered when assessing the risk of exposure to chemical mixtures that contain TDCs...- Bromate: concern for developmental neurotoxicity?K M Crofton
Neurotoxicology Division, MD B105 04, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U S EPA, Research Triangle Park, NC 27711, USA
Toxicology 221:212-6. 2006..These studies would provide invaluable data for the weight-of-evidence approach used to determine the necessity of a developmental neurotoxicity study of bromate... - PCBs, thyroid hormones, and ototoxicity in rats: cross-fostering experiments demonstrate the impact of postnatal lactation exposureK M Crofton
Neurotoxicology Division, MD 74B, National Health and Environmental Effects Research Laboratory, U S Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
Toxicol Sci 57:131-40. 2000..This effect is consistent with the greater degree of postnatal hypothyroxinemia resulting from the greater magnitude of exposure that occurs postnatally via lactation... - Undertaking positive control studies as part of developmental neurotoxicity testing: a report from the ILSI Research Foundation/Risk Science Institute expert working group on neurodevelopmental endpointsKevin M Crofton
Neurotoxicology Division, NHEERL, ORD, US EPA, Research Triangle Park, NC, USA
Neurotoxicol Teratol 30:266-87. 2008..Positive control studies should be conducted as an integral component of the incorporation and use of developmental neurotoxicity testing methods in laboratories that generate data used in risk decisions... - Hearing loss following exposure during development to polychlorinated biphenyls: a cochlear site of actionK M Crofton
Neurotoxicology Division, MD 74B, National Health and Environmental Effects Research Laboratory, US EPA, Research Triangle Park, NC 27711, USA
Hear Res 144:196-204. 2000..The mechanism that underlies this developmental ototoxicity remains to be determined. These data provide the first evidence of a structural deficit in the nervous system of adult animals exposed to PCBs during development... - Thyroid disrupting chemicals: mechanisms and mixturesKevin M Crofton
Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
Int J Androl 31:209-23. 2008..Assessing the health risks of thyroid disruption by environmental xenobiotics will need to include an improved understanding of how divergent mechanisms alter THs and consequent adverse impacts on nervous system development... - In vivo acute exposure to polychlorinated biphenyls: effects on free and total thyroxine in ratsJ M Hedge
Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US EPA, Research Triangle Park, NC 27711, USA
Int J Toxicol 28:382-91. 2009..These data demonstrate that neither PCB 153 nor PCB169 increased FT4, which supports the conclusion that these PCBs do not displace thyroxine from serum TTR, or if it does occur, there is no subsequent increase in serum FT4 in vivo... - Marginal iodide deficiency and thyroid function: dose-response analysis for quantitative pharmacokinetic modelingM E Gilbert
Toxicity Assessment Division MD B105 05, National Health and Environmental Effects Research Laboratory, U S Environmental Protection Agency, 109 TW Alexander Drive, Research Triangle Park, NC 27711, USA
Toxicology 283:41-8. 2011..These results challenge existing models and provide essential information for development of quantitative BBDR models for ID during pregnancy and lactation... - Influence of dosing volume on the neurotoxicity of bifenthrinM J Wolansky
U S National Research Council, U S EPA, Research Triangle Park, NC, USA
Neurotoxicol Teratol 29:377-84. 2007..Further, these data suggest that inconsistent estimates of pyrethroid potency between laboratories are at least partially due to differences in dosing volume... - Developmental exposure to a commercial PCB mixture (Aroclor 1254) produces a persistent impairment in long-term potentiation in the rat dentate gyrus in vivoM E Gilbert
Neurotoxicology Division, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
Brain Res 850:87-95. 1999..Disruption of early brain ontogeny due to developmental PCB exposure may underlie perturbations in the neurological substrates that support synaptic plasticity and contribute to deficits in LTP and learning that persist into adulthood... - Effects of short-term in vivo exposure to polybrominated diphenyl ethers on thyroid hormones and hepatic enzyme activities in weanling ratsT Zhou
Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina, USA
Toxicol Sci 61:76-82. 2001..DE-83R was not effective in altering any of the measured parameters. The present study suggests that short-term exposure to some commercial PBDE mixtures interferes with the thyroid hormone system via upregulation of UDPGTS:.. - Solvent-induced ototoxicity in rats: an atypical selective mid-frequency hearing deficitK M Crofton
Neurotoxicology Division, U S Environmental Protection Agency, Research Triangle Park, NC 27711
Hear Res 80:25-30. 1994..Toluene and xylene also increased thresholds at 24 kHz. These data indicate that for those solvents reported thus far to cause hearing loss, the deficit is restricted to mid-frequencies in rats... - Setting exposure standards: a decision processH A Tilson
National Health and Environmental Effects Research Laboratory, U S Environmental Protection Agency, Research Triangle Park, North Carolina, USA
Environ Health Perspect 104:401-5. 1996..An analysis of U.S. Environmental Protection Agency integrated risk information system (IRIS) indicates that about 20% of the chemicals having standards or health advisories are based on neurotoxicity... - Flash-, somatosensory-, and peripheral nerve-evoked potentials in rats perinatally exposed to Aroclor 1254D W Herr
Neurotoxicology Division, MD 74B, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U S Environmental Protection Agency, Research Triangle Park, NC 27711, USA
Neurotoxicol Teratol 23:591-601. 2001..However, subtle changes in the function of the visual or somatosensory systems cannot be disproved... - Characterization of disulfoton-induced behavioral and neurochemical effects following repeated exposureJ Llorens
Neurotoxicology Division, U S Environmental Protection Agency, Research Triangle Park, North Carolina 27711
Fundam Appl Toxicol 20:163-9. 1993..These data indicate that, in spite of muscarinic receptor down-regulation that followed repeated exposure to disulfoton, animals become tolerant to only some of the functional effects produced by this chemical... - Developmental neurotoxicity testing: recommendations for developing alternative methods for the screening and prioritization of chemicalsKevin M Crofton
National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
ALTEX 28:9-15. 2011..The intent of this document is to serve as a catalyst for engaging the research community in the development of DNT alternatives and it is expected that these recommendations will continue to evolve with the science... - Behavioral toxicology in the 21st century: challenges and opportunities for behavioral scientists. Summary of a symposium presented at the annual meeting of the neurobehavioral teratology society, June, 2009Philip J Bushnell
National Health and Environmental Effects Research Laboratory, U S Environmental Protection Agency, Research Triangle Park, NC 27711, United States
Neurotoxicol Teratol 32:313-28. 2010..Initial advances will likely provide better prioritization tools so that animal resources are used more efficiently and effectively... - Splice variant specific increase in Ca2+/calmodulin-dependent protein kinase 1-gamma mRNA expression in response to acute pyrethroid exposureJoshua A Harrill
Curriculum in Toxicology, University of North Carolina at Chapel Hill, CB 7270, Chapel Hill, NC 27599, USA
J Biochem Mol Toxicol 24:174-86. 2010..There was no increase in CAMK1G1 protein as measured with Western blots. The present data demonstrate that pyrethroid-induced changes in Camk1g are driven mainly by increased expression of the Camk1g1 splice variant... - A retrospective performance assessment of the developmental neurotoxicity study in support of OECD test guideline 426Susan L Makris
Office of Research and Development, National Center for Environmental Assessment, U S Environmental Protection Agency, Washington, DC 20460 0001, USA
Environ Health Perspect 117:17-25. 2009..Multiple independent, expert scientific peer reviews affirm these conclusions... - Assessment of DE-71, a commercial polybrominated diphenyl ether (PBDE) mixture, in the EDSP male and female pubertal protocolsTammy E Stoker
Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U S Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
Toxicol Sci 78:144-55. 2004.... - Inhalational exposure to carbonyl sulfide produces altered brainstem auditory and somatosensory-evoked potentials in Fischer 344N ratsDavid W Herr
Neurotoxicology Division, MD B105 05, NHEERL, ORD, USEPA, Research Triangle Park, North Carolina 27711, USA
Toxicol Sci 95:118-35. 2007..This series of experiments demonstrates that COS produces changes in brainstem auditory and cortical somatosensory neurophysiological responses that correlate with previously described histopathological damage... - In utero and lactational exposure to bisphenol A, in contrast to ethinyl estradiol, does not alter sexually dimorphic behavior, puberty, fertility, and anatomy of female LE ratsBryce C Ryan
Reproductive Toxicology Branch, TA Division, National Health and Environmental Effects Research Laboratory, ORD, U S Environmental Protection Agency Office of Research and Development, Research Triangle Park, North Carolina 27711, USA
Toxicol Sci 114:133-48. 2010..These results demonstrate that developmental exposure to pharmacologically relevant dosage levels of EE2 can permanently disrupt the reproductive morphology and function of the female rat... - Accumulation of PBDE-47 in primary cultures of rat neocortical cellsWilliam R Mundy
Neurotoxicology and Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U S Environmental Protection Agency, Research Triangle Park, NC 27711, USA
Toxicol Sci 82:164-9. 2004..Thus, accurate information on the tissue concentration for in vitro experiments should be determined empirically... - Developmental neurotoxicity of pyrethroid insecticides: critical review and future research needsTimothy J Shafer
Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U S Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
Environ Health Perspect 113:123-36. 2005..These studies should employ state-of-the-science methods to promote a greater understanding of the mode of action of pyrethroids in the developing nervous system... - Spatial learning and long-term potentiation in the dentate gyrus of the hippocampus in animals developmentally exposed to Aroclor 1254M E Gilbert
Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
Toxicol Sci 57:102-11. 2000.... - Time and concentration dependent accumulation of [3H]-deltamethrin in Xenopus laevis oocytesJoshua A Harrill
Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
Toxicol Lett 157:79-88. 2005..5-fold at 0.0005 ppm to 4.1-fold at 5.0 ppm. These data suggest that media concentration does not accurately predict tissue dose at all times for a broad range of deltamethrin concentrations in X. laevis oocytes... - The ototoxicity of trichloroethylene: extrapolation and relevance of high-concentration, short-duration animal exposure dataK M Crofton
National Health and Environmental Effects Research Laboratory, U S Environmental Protection Agency, Research Triangle Park, North Carolina, 27711, USA
Fundam Appl Toxicol 38:101-6. 1997..Furthermore, these data suggest that, relative to ambient or occupational exposures, the ototoxicity of TCE in the rat is a high-concentration effect... - Schedule-controlled behavior in rats exposed perinatally to the PCB mixture Aroclor 1254M M Taylor
Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
Neurotoxicol Teratol 24:511-8. 2002..These data are inconsistent with previous findings and suggest that perinatal A1254 exposure in the rat does not disrupt temporally organized behavior... - Comparison of PC12 and cerebellar granule cell cultures for evaluating neurite outgrowth using high content analysisNicholas M Radio
Neurotoxicology Division, NHEERL, ORD, USEPA, Research Triangle Park, NC, USA
Neurotoxicol Teratol 32:25-35. 2010..These findings demonstrate that the effects of chemicals on neurite outgrowth may be cell type specific... - Neurotoxic and pharmacokinetic responses to trichloroethylene as a function of exposure scenarioW K Boyes
Neurotoxicology Division, U S Environmental Protection Agency, Research Triangle Park, NC 27711, USA
Environ Health Perspect 108:317-22. 2000..We conclude that models incorporating dosimetry can account for differing exposure scenarios and will therefore improve risk assessments over models considering only parameters of external exposure... - Relative potencies for acute effects of pyrethroids on motor function in ratsM J Wolansky
National Research Council, Research Triangle Park, North Carolina 27711, USA
Toxicol Sci 89:271-7. 2006..Relative potency ratios ranged from 0.009 (resmethrin) to 2.092 (esfenvalerate). Additional work with environmentally-based mixtures is needed to test the hypothesis of dose-additivity of pyrethroids... - Overview: Using mode of action and life stage information to evaluate the human relevance of animal toxicity dataJennifer Seed
US Environmental Protection Agency, Washington, DC, USA
Crit Rev Toxicol 35:664-72. 2005.... - Low-dose effects of ammonium perchlorate on the hypothalamic-pituitary-thyroid axis of adult male rats pretreated with PCB126Eva D McLanahan
Interdisciplinary Toxicology Program, University of Georgia, Athens, GA 30602, USA
Toxicol Sci 97:308-17. 2007..At relatively low doses, at or near the no-observed-effect-level for PCB126 and ClO(4)(-), no interactions between the chemicals occur... - Perinatal exposure to Aroclor 1254 impairs distortion product otoacoustic emissions (DPOAEs) in ratsRobert E Lasky
Center for Clinical Research and Evidence Based Medicine, University of Texas Health Science Center at Houston Medical School, 6431 Fannin, MSB 2 104, Houston, Texas 77030 1503, USA
Toxicol Sci 68:458-64. 2002..In contrast, ABR latencies and amplitudes were not altered by A1254 exposure. These findings provide the first functional evidence supporting a cochlear site of damage in PCB-induced hearing loss... - Effect of PCB 126 on hepatic metabolism of thyroxine and perturbations in the hypothalamic-pituitary-thyroid axis in the ratJeffrey W Fisher
University of Georgia, Interdisciplinary Toxicology Program, Athens, Georgia 30602, USA
Toxicol Sci 90:87-95. 2006..However, the dose-response characteristics of the HPT axis are nonlinear and complex, requiring sophisticated tools, such as PBPK models, to characterize dose response... - Behavioral test methods workshopWilliam Slikker
National Center for Toxicological Research FDA, Division of Neurotoxicology, 3900 NCTR Rd Jefferson 72079, United States
Neurotoxicol Teratol 27:417-27. 2005.... - Comparative responsiveness of hypothyroxinemia and hepatic enzyme induction in Long-Evans rats versus C57BL/6J mice exposed to TCDD-like and phenobarbital-like polychlorinated biphenyl congenersElena S Craft
Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina, USA
Toxicol Sci 68:372-80. 2002..These data suggest that species differences in response to chemicals that induce hypothyroxinemia are due to differential induction of hepatic UGT enzymes... - Comments on: Effect of prenatal exposure of deltamethrin on the ontogeny of xenobiotic metabolizing cytochrome P450s in the brain and liver of offsprings [Johri et al. Toxicol Appl Pharmacol. 214:279-289, 2006]Kevin M Crofton
Toxicol Appl Pharmacol 218:96-7; author reply 98. 2007 - Concentration-dependent accumulation of [3H]-deltamethrin in sodium channel Nav1.2/beta1 expressing Xenopus laevis oocytesJennifer A Watkins
North Carolina State University, Raleigh, NC 27695, USA
Toxicol In Vitro 21:1672-7. 2007..51+/-0.07 ppm DLT. There was a significant difference in DLT accumulation between VSSC-transfected oocytes and non-transfected controls, where the transfected oocytes consistently had less accumulation... - Developmental exposure to brominated diphenyl ethers results in thyroid hormone disruptionTong Zhou
Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina, USA
Toxicol Sci 66:105-16. 2002..8-fold; UDPGT = 0.5-fold). These data support the conclusion that DE-71 is an endocrine disrupter in rats during development... - Mode of action: developmental thyroid hormone insufficiency--neurological abnormalities resulting from exposure to propylthiouracilR Thomas Zoeller
University of Massachusetts Amherst, Department of Biology, Morrill Science Center, 01003, USA
Crit Rev Toxicol 35:771-81. 2005....