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Yi J, Ma Y, Ma J, Yu H, Zhang K, Jin L, Yang Q, Sun D, Wu D. Rapid Assessment of Ocular Toxicity from Environmental Contaminants Based on Visually Mediated Zebrafish Behavior Studies. TOXICS 2023; 11:706. [PMID: 37624211 PMCID: PMC10459940 DOI: 10.3390/toxics11080706] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/04/2023] [Accepted: 08/14/2023] [Indexed: 08/26/2023]
Abstract
The presence of contaminants in the environment has increased in recent years, and studies have demonstrated that these contaminants have the ability to penetrate the blood-retinal barrier and directly affect the visual systems of organisms. Zebrafish are recognized as an ideal model for human eye diseases due to their anatomical and functional similarities to the human eye, making them an efficient and versatile organism for studying ocular toxicity caused by environmental contaminants in the field of environmental toxicology. Meanwhile, zebrafish exhibit a diverse repertoire of visually mediated behaviors, and their visual system undergoes complex changes in behavioral responses when exposed to environmental contaminants, enabling rapid assessment of the ocular toxicity induced by such pollutants. Therefore, this review aimed to highlight the effectiveness of zebrafish as a model for examining the effects of environmental contaminants on ocular development. Special attention is given to the visually mediated behavior of zebrafish, which allows for a rapid assessment of ocular toxicity resulting from exposure to environmental contaminants. Additionally, the potential mechanisms by which environmental contaminants may induce ocular toxicity are briefly outlined.
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Affiliation(s)
- Jia Yi
- Institute of Life Science & Biomedical Collaborative Innovation Center of Zhejiang Province, Wenzhou University, Wenzhou 325035, China
| | - Yilei Ma
- Institute of Life Science & Biomedical Collaborative Innovation Center of Zhejiang Province, Wenzhou University, Wenzhou 325035, China
| | - Jiahui Ma
- Institute of Life Science & Biomedical Collaborative Innovation Center of Zhejiang Province, Wenzhou University, Wenzhou 325035, China
| | - Haiyang Yu
- Institute of Life Science & Biomedical Collaborative Innovation Center of Zhejiang Province, Wenzhou University, Wenzhou 325035, China
| | - Kun Zhang
- Bioengineering College of Chongqing University, Chongqing 400030, China
| | - Libo Jin
- National and Local Joint Engineering Research Center for Ecological Treatment Technology of Urban Water Pollution, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China;
| | - Qinsi Yang
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325000, China;
| | - Da Sun
- Institute of Life Science & Biomedical Collaborative Innovation Center of Zhejiang Province, Wenzhou University, Wenzhou 325035, China
- National and Local Joint Engineering Research Center for Ecological Treatment Technology of Urban Water Pollution, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China;
| | - Dejun Wu
- Emergency Department, Quzhou People’s Hospital, Quzhou 324000, China
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Huang W, Wu T, Wu R, Peng J, Zhang Q, Shi X, Wu K. Fish to learn: insights into the effects of environmental chemicals on eye development and visual function in zebrafish. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-27629-3. [PMID: 37195602 DOI: 10.1007/s11356-023-27629-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 05/10/2023] [Indexed: 05/18/2023]
Abstract
Vision is the most essential sense system for the human being. Congenital visual impairment affects millions of people globally. It is increasingly realized that visual system development is an impressionable target of environmental chemicals. However, due to inaccessibility and ethical issues, the use of humans and other placental mammals is constrained, which limits our better understanding of environmental factors on ocular development and visual function in the embryonic stage. Therefore, as complementing laboratory rodents, zebrafish has been the most frequently employed to understand the effects of environmental chemicals on eye development and visual function. One of the major reasons for the increasing use of zebrafish is their polychromatic vision. Zebrafish retinas are morphologically and functionally analogous to those of mammalian, as well as evolutionary conservation among vertebrate eye. This review provides an update on harmful effects from exposure to environmental chemicals, involving metallic elements (ions), metal-derived nanoparticles, microplastics, nanoplastics, persistent organic pollutants, pesticides, and pharmaceutical pollutants on the eye development and visual function in zebrafish embryos. The collected data provide a comprehensive understanding of environmental factors on ocular development and visual function. This report highlights that zebrafish is promising as a model to identify hazardous toxicants toward eye development and is hopeful for developing preventative or postnatal therapies for human congenital visual impairment.
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Affiliation(s)
- Wenlong Huang
- Guangdong Provincial Key Laboratory of Breast Cancer Diagnosis and Treatment, Department of Preventive Medicine, Shantou University Medical College, Xinling Rd., No. 22, Shantou, 515041, Guangdong, China
- Department of Forensic Medicine, Shantou University Medical College, Shantou, 515041, Guangdong, China
| | - Tianjie Wu
- Department of Anaesthesiology, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-Sen University, Shantou, 515041, Guangdong, China
| | - Ruotong Wu
- School of Life Science, Xiamen University, Xiamen, 361102, Fujian, China
| | - Jiajun Peng
- Guangdong Provincial Key Laboratory of Breast Cancer Diagnosis and Treatment, Department of Preventive Medicine, Shantou University Medical College, Xinling Rd., No. 22, Shantou, 515041, Guangdong, China
| | - Qiong Zhang
- Guangdong Provincial Key Laboratory of Breast Cancer Diagnosis and Treatment, Department of Preventive Medicine, Shantou University Medical College, Xinling Rd., No. 22, Shantou, 515041, Guangdong, China
| | - Xiaoling Shi
- Guangdong Provincial Key Laboratory of Breast Cancer Diagnosis and Treatment, Department of Preventive Medicine, Shantou University Medical College, Xinling Rd., No. 22, Shantou, 515041, Guangdong, China
| | - Kusheng Wu
- Guangdong Provincial Key Laboratory of Breast Cancer Diagnosis and Treatment, Department of Preventive Medicine, Shantou University Medical College, Xinling Rd., No. 22, Shantou, 515041, Guangdong, China.
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Polevoy C, Arbuckle TE, Oulhote Y, Lanphear BP, Cockell KA, Muckle G, Saint-Amour D. Prenatal exposure to legacy contaminants and visual acuity in Canadian infants: a maternal-infant research on environmental chemicals study (MIREC-ID). Environ Health 2020; 19:14. [PMID: 32028962 PMCID: PMC7006412 DOI: 10.1186/s12940-020-0567-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 01/22/2020] [Indexed: 05/28/2023]
Abstract
BACKGROUND Prenatal exposure to environmental contaminants can have deleterious effects on child development. While psychomotor, cognitive and behavioural outcomes have been investigated in relation to chronic exposure, the associations with visual functions remains unclear. The present study's aim was to assess the associations of prenatal exposure to legacy persistent organic pollutants and heavy metals with visual acuity in Canadian infants. The potential protective effects of selenium against mercury toxicity were also examined. METHODS Participants (mean corrected age = 6.6 months) were part of the Maternal-Infant Research on Environmental Chemicals (MIREC) study. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), lead and mercury were measured in maternal blood during pregnancy, as well as in the cord blood. The Teller acuity card test (TAC) (n = 429) and the visual evoked potentials in a sub-group (n = 63) were used to estimate behavioural and electrophysiological visual acuity, respectively. Multivariable linear regression models were used to investigate the relationship between exposure to each contaminant and visual acuity measures, while controlling for potential confounders. Breastmilk selenium, which was available for about half of the TAC and VEP samples, was also taken into account in the mercury models as exploratory analyses. RESULTS We observed no significant associations between exposure to any contaminants and TAC. Analyses revealed a negative trend (p values < 0.1) between cord blood lead and mercury and electrophysiological visual acuity, whereas PCB and PBDE showed no association. When adding breastmilk selenium concentration to the mercury models, this association became statistically significant for cord concentrations (β = - 3.41, 95% CI = - 5.96,-0.86), but also for blood levels at 1st and 3rd trimesters of pregnancy (β = - 3.29, 95% CI = - 5.69,-0.88). However, further regression models suggested that this change in estimates might not be due to adjustment for selenium, but instead to a change in the study sample. CONCLUSIONS Our results suggest that subtle, but detectable alterations of infant electrophysiological visual acuity can be identified in a population prenatally exposed to low mercury concentrations. Compared to behavioural visual acuity testing, electrophysiological assessment may more sensitive in detecting visual neurotoxicity in relation with prenatal exposure to mercury.
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Affiliation(s)
- C Polevoy
- Centre de recherche, CHU Sainte-Justine, QC, Montréal, Canada
- Département de psychologie, Université du Québec à Montréal, QC, Montréal, Canada
| | - T E Arbuckle
- Population Studies Division, Environmental Health Science and Research Bureau, Health Canada, Ottawa, ON, Canada
| | - Y Oulhote
- Department of Biostatistics and Epidemiology, School of Public health and health Sciences, University of Massachusetts at Amherst, Amherst, MA, USA
| | - B P Lanphear
- BC Children's Hospital, Simon Fraser University, Burnaby, Canada
| | - K A Cockell
- Nutrition Research Division, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, ON, Canada
| | - G Muckle
- École de psychologie, Université Laval and Centre de recherche du CHU de Québec-Université Laval, Québec, QC, Canada
| | - D Saint-Amour
- Centre de recherche, CHU Sainte-Justine, QC, Montréal, Canada.
- Département de psychologie, Université du Québec à Montréal, QC, Montréal, Canada.
- Département d'ophtalmologie, Université de Montréal, QC, Montréal, Canada.
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Du Y, Ge MM, Xue W, Yang QQ, Wang S, Xu Y, Wang HL. Chronic Lead Exposure and Mixed Factors of Gender×Age×Brain Regions Interactions on Dendrite Growth, Spine Maturity and NDR Kinase. PLoS One 2015; 10:e0138112. [PMID: 26368815 PMCID: PMC4569283 DOI: 10.1371/journal.pone.0138112] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Accepted: 08/26/2015] [Indexed: 02/01/2023] Open
Abstract
NDR1/2 kinase is essential in dendrite morphology and spine formation, which is regulated by cellular Ca2+. Lead (Pb) is a potent blocker of L-type calcium channel and our recent work showed Pb exposure impairs dendritic spine outgrowth in hippocampal neurons in rats. But the sensitivity of Pb-induced spine maturity with mixed factors (gender×age×brain regions) remains unknown. This study aimed to systematically investigate the effect of Pb exposure on spine maturity in rat brain with three factors (gender×age×brain regions), as well as the NDR1/2 kinase expression. Sprague–Dawley rats were exposed to Pb from parturition to postnatal day 30, 60, 90, respectively. Golgi-Cox staining was used to examine spine maturity. Western blot assay was applied to measure protein expression and real-time fluorescence quantitative PCR assay was used to examine mRNA levels. The results showed chronic Pb exposure significantly decreased dendritic length and impaired spine maturity in both rat hippocampus and medial prefrontal cortex. The impairment of dendritic length induced by Pb exposure tended to adolescence > adulthood, hippocampus > medial prefrontal cortex and female > male. Pb exposure induced significant damage in spine maturity during adolescence and early adult while little damage during adult in male rat brain and female medial prefrontal cortex. Besides, there was sustained impairment from adolescence to adulthood in female hippocampus. Interestingly, impairment of spine maturity followed by Pb exposure was correlated with NDR1/2 kinase. The reduction of NDR1/2 kinase protein expression after Pb exposure was similar to the result of spine maturity. In addition, NDR2 and their substrate Rabin3 mRNA levels were significantly decreased by Pb exposure in developmental rat brain. Taken together, Pb exposure impaired dendrite growth and maturity which was subject to gender×age×brain regions effects and related to NDR1/2 signal expression.
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Affiliation(s)
- Yang Du
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China
| | - Meng-Meng Ge
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China
| | - Weizhen Xue
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China
| | - Qian-Qian Yang
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China
| | - Shuang Wang
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China
| | - Yi Xu
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China
| | - Hui-Li Wang
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China
- * E-mail:
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Bault ZA, Peterson SM, Freeman JL. Directional and color preference in adult zebrafish: Implications in behavioral and learning assays in neurotoxicology studies. J Appl Toxicol 2015; 35:1502-10. [PMID: 25993913 DOI: 10.1002/jat.3169] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 04/08/2015] [Indexed: 02/04/2023]
Affiliation(s)
- Zachary A. Bault
- School of Health Sciences; Purdue University; West Lafayette IN USA
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Frye CA. Endocrine-disrupting chemicals: elucidating our understanding of their role in sex and gender-relevant end points. VITAMINS AND HORMONES 2014; 94:41-98. [PMID: 24388187 DOI: 10.1016/b978-0-12-800095-3.00003-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Endocrine-disrupting chemicals (EDCs) are diverse and pervasive and may have significant consequence for health, including reproductive development and expression of sex-/gender-sensitive parameters. This review chapter discusses what is known about common EDCs and their effects on reproductively relevant end points. It is proposed that one way that EDCs may exert such effects is by altering steroid levels (androgens or 17-estradiol, E₂) and/or intracellular E₂ receptors (ERs) in the hypothalamus and/or hippocampus. Basic research findings that demonstrate developmentally sensitive end points to androgens and E₂ are provided. Furthermore, an approach is suggested to examine differences in EDCs that diverge in their actions at ERs to elucidate their role in sex-/gender-sensitive parameters.
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Affiliation(s)
- Cheryl A Frye
- Department of Psychology, The University at Albany-SUNY, Albany, New York, USA; Department of Biological Sciences, The University at Albany-SUNY, Albany, New York, USA; The Center for Neuroscience Research, The University at Albany-SUNY, Albany, New York, USA; The Center for Life Sciences Research, The University at Albany-SUNY, Albany, New York, USA; Department of Chemistry, University of Alaska Fairbanks, Fairbanks, Alaska, USA; IDeA Network of Biomedical Excellence (INBRE), University of Alaska Fairbanks, Fairbanks, Alaska, USA; Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska, USA.
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Toxic risks and nutritional benefits of traditional diet on near visual contrast sensitivity and color vision in the Brazilian Amazon. Neurotoxicology 2013; 37:173-81. [DOI: 10.1016/j.neuro.2013.04.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 04/04/2013] [Accepted: 04/19/2013] [Indexed: 11/22/2022]
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Kim DS, Kwon YM, Chung HU, Choi KH, Oh HJ, Lee EH. Mercury exposure and color vision loss of some Koreans in a fishery area. Mol Cell Toxicol 2012. [DOI: 10.1007/s13273-012-0050-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Effects of environmental contaminant exposure on visual brain development: A prospective electrophysiological study in school-aged children. Neurotoxicology 2012; 33:1075-85. [DOI: 10.1016/j.neuro.2012.05.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2010] [Revised: 05/10/2012] [Accepted: 05/10/2012] [Indexed: 11/20/2022]
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Fox DA, Grandjean P, de Groot D, Paule M. Developmental origins of adult diseases and neurotoxicity: epidemiological and experimental studies. Neurotoxicology 2012; 33:810-6. [PMID: 22245043 PMCID: PMC3657611 DOI: 10.1016/j.neuro.2011.12.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 12/22/2011] [Accepted: 12/22/2011] [Indexed: 10/14/2022]
Abstract
To date, only a small number of commercial chemicals have been tested and documented as developmental neurotoxicants. Moreover, an increasing number of epidemiological, clinical and experimental studies suggest an association between toxicant or drug exposure during the perinatal period and the development of metabolic-related diseases and neurotoxicity later in life. The four speakers at this symposium presented their research results on different neurotoxic chemicals relating to the developmental origins of health and adult disease (DOHaD). Philippe Grandjean presented epidemiological data on children exposed to inorganic mercury and methylmercury, and discussed the behavioral outcome measures as they relate to age and stage of brain development. Donald A. Fox presented data that low-dose human equivalent gestational lead exposure produces late-onset obesity only in male mice that is associated with neurodegeneration. Didima de Groot presented results on prenatal exposure of rats to methylazoxymethanol and discussed the results in light of the etiology of western Pacific amyotrophic lateral sclerosis and Parkinson-dementia complex. Merle G. Paule addressed the long-term changes in learning, motivation and short-term memory in aged Rhesus monkeys following acute 24 h exposure to ketamine during early development. Overall, these presentations addressed fundamental issues in the emerging areas of lifetime neurotoxicity testing, differential vulnerable periods of exposure, nonmonotonic dose-response effects and neurotoxic risk assessment. The results indicate that developmental neurotoxicity results in permanent changes, thus emphasizing the need to prevent such toxicity.
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Affiliation(s)
- Donald A. Fox
- University of Houston, College of Optometry, Department of Biology and Biochemistry, and Department of Pharmaceutical Sciences, Houston, TX, USA
| | - Philippe Grandjean
- Department of Environmental Health, Harvard School of Public Health, Boston, USA and Department of Environmental Medicine, University of Southern Denmark, Odense, Denmark,
| | - Didima de Groot
- Toxicology & Applied Pharmacology, TNO Quality of Life, Zeist, Netherlands,
| | - Merle Paule
- Division of Neurotoxicology, National Center for Toxicological Research, FDA, Jefferson, AR, USA,
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Fox DA, Hamilton WR, Johnson JE, Xiao W, Chaney S, Mukherjee S, Miller DB, O'Callaghan JP. Gestational lead exposure selectively decreases retinal dopamine amacrine cells and dopamine content in adult mice. Toxicol Appl Pharmacol 2011; 256:258-67. [PMID: 21703292 DOI: 10.1016/j.taap.2011.05.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 05/30/2011] [Accepted: 05/31/2011] [Indexed: 10/18/2022]
Abstract
Gestational lead exposure (GLE) produces supernormal scotopic electroretinograms (ERG) in children, monkeys and rats, and a novel retinal phenotype characterized by an increased number of rod photoreceptors and bipolar cells in adult mice and rats. Since the loss of dopaminergic amacrine cells (DA ACs) in GLE monkeys and rats contributes to supernormal ERGs, the retinal DA system was analyzed in mice following GLE. C57BL/6 female mice were exposed to low (27 ppm), moderate (55 ppm) or high (109 ppm) lead throughout gestation and until postnatal day 10 (PN10). Blood [Pb] in control, low-, moderate- and high-dose GLE was ≤ 1, ≤ 10, ~25 and ~40 μg/dL, respectively, on PN10 and by PN30 all were ≤ 1 μg/dL. At PN60, confocal-stereology studies used vertical sections and wholemounts to characterize tyrosine hydroxylase (TH) expression and the number of DA and other ACs. GLE dose-dependently and selectively decreased the number of TH-immunoreactive (IR) DA ACs and their synaptic plexus without affecting GABAergic, glycinergic or cholinergic ACs. Immunoblots and confocal revealed dose-dependent decreases in retinal TH protein expression and content, although monoamine oxidase-A protein and gene expression were unchanged. High-pressure liquid chromatography showed that GLE dose-dependently decreased retinal DA content, its metabolites and DA utilization/release. The mechanism of DA selective vulnerability is unknown. However, a GLE-induced loss/dysfunction of DA ACs during development could increase the number of rods and bipolar cells since DA helps regulate neuronal proliferation, whereas during adulthood it could produce ERG supernormality as well as altered circadian rhythms, dark/light adaptation and spatial contrast sensitivity.
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Affiliation(s)
- Donald A Fox
- College of Optometry, University of Houston, Houston, TX 77204-2020, USA.
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Fox DA, Opanashuk L, Zharkovsky A, Weiss B. Gene-chemical interactions in the developing mammalian nervous system: Effects on proliferation, neurogenesis and differentiation. Neurotoxicology 2010; 31:589-97. [PMID: 20381523 DOI: 10.1016/j.neuro.2010.03.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 03/19/2010] [Accepted: 03/22/2010] [Indexed: 12/01/2022]
Abstract
The orderly formation of the nervous system requires a multitude of complex, integrated and simultaneously occurring processes. Neural progenitor cells expand through proliferation, commit to different cell fates, exit the cell cycle, generate different neuronal and glial cell types, and new neurons migrate to specified areas and establish synaptic connections. Gestational and perinatal exposure to environmental toxicants, pharmacological agents and drugs of abuse produce immediate, persistent or late-onset alterations in behavioral, cognitive, sensory and/or motor functions. These alterations reflect the disruption of the underlying processes of CNS formation and development. To determine the neurotoxic mechanisms that underlie these deficits it is necessary to analyze and dissect the complex molecular processes that occur during the proliferation, neurogenesis and differentiation of cells. This symposium will provide a framework for understanding the orchestrated events of neurogenesis, the coordination of proliferation and cell fate specification by selected genes, and the effects of well-known neurotoxicants on neurogenesis in the retina, hippocampus and cerebellum. These three tissues share common developmental profiles, mediate diverse neuronal activities and function, and thus provide important substrates for analysis. This paper summarizes four invited talks that were presented at the 12th International Neurotoxicology Association meeting held in Jerusalem, Israel during the summer of 2009. Donald A. Fox described the structural and functional alterations following low-level gestational lead exposure in children and rodents that produced a supernormal electroretinogram and selective increases in neurogenesis and cell proliferation of late-born retinal neurons (rod photoreceptors and bipolar cells), but not Müller glia cells, in mice. Lisa Opanashuk discussed how dioxin [TCDD] binding to the arylhydrocarbon receptor [AhR], a transcription factor that regulates xenobiotic metabolizing enzymes and growth factors, increased granule cell formation and apoptosis in the developing mouse cerebellum. Alex Zharkovsky described how postnatal early postnatal lead exposure decreased cell proliferation, neurogenesis and gene expression in the dentate gyrus of the adult hippocampus and its resultant behavioral effects. Bernard Weiss illustrated how environmental endocrine disruptors produced age- and sex-dependent alterations in synaptogenesis and cognitive behavior.
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Affiliation(s)
- Donald A Fox
- University of Houston, College of Optometry, Department of Biology and Biochemistry, 4901 Calhoun Road, Houston, TX 77024-2020, USA.
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Preliminary Findings on the Effects of Occupational Exposure to Mercury Vapor Below Safety Levels on Visual and Neuropsychological Functions. J Occup Environ Med 2009; 51:1403-12. [DOI: 10.1097/jom.0b013e3181bca9ea] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Pb2+: an endocrine disruptor in Drosophila? Physiol Behav 2009; 99:254-9. [PMID: 19800356 DOI: 10.1016/j.physbeh.2009.09.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 09/10/2009] [Accepted: 09/17/2009] [Indexed: 11/24/2022]
Abstract
Environmental exposure to Pb(2+) affects hormone-mediated responses in vertebrates. To help establish the fruit fly, Drosophila melanogaster, as a model system for studying such disruption, we describe effects of Pb(2+) on hormonally regulated traits. These include duration of development, longevity, females' willingness to mate, fecundity and adult locomotor activity. Developmental Pb(2+) exposure has been shown to affect gene expression in a specific region of the Drosophila genome (approximately 122 genes) involved in lead-induced changes in adult locomotion and to affect regulation of intracellular calcium levels associated with neuronal activity at identified synapses in the larval neuromuscular junction. We suggest ways in which Drosophila could become a new model system for the study of endocrine disruptors at genetic, neural and behavioral levels of analysis, particularly by use of genomic methods. This will facilitate efforts to distinguish between behavioral effects of Pb(2+) caused by direct action on neural mechanisms versus effects of Pb(+2) on behavior mediated through endocrine disruption.
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Laughlin NK, Luck ML, Lasky RE. Early lead exposure effects on an auditory threshold task in the rhesus monkey (Macaca mulatta). Dev Psychobiol 2009; 51:289-300. [PMID: 19145592 DOI: 10.1002/dev.20364] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Behavioral thresholds to pure tones were obtained from adult rhesus monkeys that had been exposed to lead during early development and unexposed cohort controls. Thresholds were elevated (by 2-9 dB) for the previously lead exposed monkeys at all frequencies tested (125-8,000 Hz in octave steps). Although the magnitude and direction of the differences were similar to significant effects reported for children, the more difficult task and much smaller sample sizes in this study of monkeys may have precluded obtaining significant differences at the same magnitude of effects observed in children. Thresholds for one lead-exposed monkey were significantly elevated at midrange frequencies in agreement with electrophysiological results obtained in another study [Lasky, Maier, Snodgrass, Hecox, and Laughlin [1995] Neurotoxicology and Teratology, 17, 633-644]. Behavioral measurements during the threshold task indicated less engagement for lead exposed monkeys than for controls. In addition, the lead exposed monkeys completed testing at significantly fewer frequencies and were significantly more difficult to test than control monkeys by tester ratings. These results are consistent with reports concerning the behavior of lead exposed children.
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Affiliation(s)
- Nellie K Laughlin
- Harlow Center for Biological Psychology, The University of Wisconsin-Madison, Madison, Wisconsin 53715, USA
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Boucher O, Muckle G, Saint-Amour D, Dewailly E, Ayotte P, Jacobson SW, Jacobson JL, Bastien CH. The relation of lead neurotoxicity to the event-related potential P3b component in Inuit children from arctic Québec. Neurotoxicology 2009; 30:1070-7. [PMID: 19576242 DOI: 10.1016/j.neuro.2009.06.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 06/05/2009] [Accepted: 06/19/2009] [Indexed: 11/30/2022]
Abstract
The event-related potential (ERP) P3b, a cognitive electrophysiological measure that has been linked to working memory processing in many experimental paradigms, was measured in Inuit children from Nunavik (Arctic Québec, Canada) to assess lead (Pb) neurotoxicity. Visual and auditory oddball paradigms were administered at 5 (N=27) and 11 (N=110) years of age, respectively, to elicit this ERP component. Pearson correlations and multiple regression analyses were performed to examine the associations between Pb levels and P3b parameters (peak latency and amplitude). Greater prenatal Pb exposure was related to a decrease in P3b amplitude at 5 years of age, and early childhood Pb exposure was associated with delayed P3b latency at 5 years. No significant association was observed at 11 years. These results, in line with those from previous neurobehavioral studies, suggest that Pb exposure affects cognitive processing in children even though the Pb levels measured in a large majority of our sample were below the threshold value for public health intervention used by federal agencies. This study strengthens the arguments for reducing sources of Pb exposure in Nunavik and for lowering the blood Pb concentrations considered "acceptable" in governmental policies.
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Hirsch HVB, Possidente D, Averill S, Despain TP, Buytkins J, Thomas V, Goebel WP, Shipp-Hilts A, Wilson D, Hollocher K, Possidente B, Lnenicka G, Ruden DM. Variations at a quantitative trait locus (QTL) affect development of behavior in lead-exposed Drosophila melanogaster. Neurotoxicology 2009; 30:305-11. [PMID: 19428504 DOI: 10.1016/j.neuro.2009.01.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 12/31/2008] [Accepted: 01/12/2009] [Indexed: 12/01/2022]
Abstract
We developed Drosophila melanogaster as a model to study correlated behavioral, neuronal and genetic effects of the neurotoxin lead, known to affect cognitive and behavioral development in children. We showed that, as in vertebrates, lead affects both synaptic development and complex behaviors (courtship, fecundity, locomotor activity) in Drosophila. By assessing differential behavioral responses to developmental lead exposure among recombinant inbred Drosophila lines (RI), derived from parental lines Oregon R and Russian 2b, we have now identified a genotype by environment interaction (GEI) for a behavioral trait affected by lead. Drosophila Activity Monitors (TriKinetics, Waltham, MA), which measure activity by counting the number of times a single fly in a small glass tube walks through an infrared beam aimed at the middle of the tube, were used to measure activity of flies, reared from eggs to 4 days of adult age on either control or lead-contaminated medium, from each of 75 RI lines. We observed a significant statistical association between the effect of lead on Average Daytime Activity (ADA) across lines and one marker locus, 30AB, on chromosome 2; we define this as a Quantitative Trait Locus (QTL) associated with behavioral effects of developmental lead exposure. When 30AB was from Russian 2b, lead significantly increased locomotor activity, whereas, when 30AB was from Oregon R, lead decreased it. 30AB contains about 125 genes among which are likely "candidate genes" for the observed lead-dependent behavioral changes. Drosophila are thus a useful, underutilized model for studying behavioral, synaptic and genetic changes following chronic exposure to lead or other neurotoxins during development.
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Affiliation(s)
- Helmut V B Hirsch
- Department of Biology, University at Albany, SUNY, Albany, NY 12222, USA.
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18
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Laughlin NK, Luck ML, Lasky RE. Postnatal lead effects on the development of visual spatial acuity in rhesus monkeys (Macaca Mulatta). Dev Psychobiol 2009; 50:608-14. [PMID: 18683184 DOI: 10.1002/dev.20315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
High lead levels adversely affect visual function in humans and laboratory animals. The effects of lower lead levels are less certain. This study compared the development of photopic spatial acuity in rhesus monkeys exposed to lead (n = 43) with monkeys (n = 23) not exposed to lead. Lead exposure began at Day 8 postpartum and continued daily throughout the first 26 weeks of postnatal life achieving target blood lead levels of 35-40 microg/dl by about 15 weeks. Photopic spatial acuity was evaluated by a preferential looking technique used clinically to assess spatial acuity in human infants. Acuity increased rapidly over the first few postnatal weeks achieving the maximum acuity level assessed (26.3 c/deg) by 7 weeks of age for most monkeys. Postnatal lead exposure at the dosages and durations studied did not affect the development of photopic spatial acuity.
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Affiliation(s)
- Nellie K Laughlin
- Harlow Center for Biological Psychology, The University of Wisconsin-Madison, Madison, WI 53715, USA
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19
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Costa MF, Tomaz S, de Souza JM, Silveira LCDL, Ventura DF. Electrophysiological evidence for impairment of contrast sensitivity in mercury vapor occupational intoxication. ENVIRONMENTAL RESEARCH 2008; 107:132-138. [PMID: 18045587 DOI: 10.1016/j.envres.2007.10.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 09/28/2007] [Accepted: 10/17/2007] [Indexed: 05/25/2023]
Abstract
Contrast sensitivity (CS) was evaluated in 41 former workers from a lamp manufacturing plant who were on disability retirement due to exposure to mercury and 14 age-matched controls. The CS was measured monocularly using the sweep visual evoked potential (sVEP) paradigm at 6 spatial frequencies (0.2, 0.8, 2.0, 4.0, 15.0, and 30 cpd). Statistical difference (p<0.05) was found between the controls and the patient right and left eyes for 2.0 and 4.0 cpd. According the results in those spatial frequencies the eyes were classified in best and worst. Statistical differences were found between the controls and the best eyes for 2.0 and 4.0 cpd and for 0.8, 2.0, and 4.0 cpd for their worst eyes. No correlation was found between CS results and the time of exposure (mean=8.9 yr+/-4.1), time away from the mercury source (mean=6.0 yr+/-3.9), urinary mercury level at the time of work (mean=40.6 microg/g+/-36.3) or with the mercury level at the CS measurement time (mean=1.6 microg/g+/-1.1). We show the first evidence of a permanent impairment in CS measured objectively with the sVEP. Our data complement the previous psychophysical works reporting a diffuse impairment in the CS function showing a CS reduction in the low to middle spatial frequencies. In conclusion, non-reversible CS impairment was found in occupational exposure to mercury vapor. We suggest that CS measurement should be included in studies of the mercury effects of occupational exposure.
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Affiliation(s)
- Marcelo Fernandes Costa
- Departamento de Psicologia Experimental, Instituto de Psicologia, Universidade de São Paulo, Av. Prof. Mello Moraes, 1721 Bloco A sala D-9, São Paulo 05508-900, SP, Brazil.
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20
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Wigle DT, Arbuckle TE, Turner MC, Bérubé A, Yang Q, Liu S, Krewski D. Epidemiologic evidence of relationships between reproductive and child health outcomes and environmental chemical contaminants. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2008; 11:373-517. [PMID: 18074303 DOI: 10.1080/10937400801921320] [Citation(s) in RCA: 281] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
This review summarizes the level of epidemiologic evidence for relationships between prenatal and/or early life exposure to environmental chemical contaminants and fetal, child, and adult health. Discussion focuses on fetal loss, intrauterine growth restriction, preterm birth, birth defects, respiratory and other childhood diseases, neuropsychological deficits, premature or delayed sexual maturation, and certain adult cancers linked to fetal or childhood exposures. Environmental exposures considered here include chemical toxicants in air, water, soil/house dust and foods (including human breast milk), and consumer products. Reports reviewed here included original epidemiologic studies (with at least basic descriptions of methods and results), literature reviews, expert group reports, meta-analyses, and pooled analyses. Levels of evidence for causal relationships were categorized as sufficient, limited, or inadequate according to predefined criteria. There was sufficient epidemiological evidence for causal relationships between several adverse pregnancy or child health outcomes and prenatal or childhood exposure to environmental chemical contaminants. These included prenatal high-level methylmercury (CH(3)Hg) exposure (delayed developmental milestones and cognitive, motor, auditory, and visual deficits), high-level prenatal exposure to polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and related toxicants (neonatal tooth abnormalities, cognitive and motor deficits), maternal active smoking (delayed conception, preterm birth, fetal growth deficit [FGD] and sudden infant death syndrome [SIDS]) and prenatal environmental tobacco smoke (ETS) exposure (preterm birth), low-level childhood lead exposure (cognitive deficits and renal tubular damage), high-level childhood CH(3)Hg exposure (visual deficits), high-level childhood exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (chloracne), childhood ETS exposure (SIDS, new-onset asthma, increased asthma severity, lung and middle ear infections, and adult breast and lung cancer), childhood exposure to biomass smoke (lung infections), and childhood exposure to outdoor air pollutants (increased asthma severity). Evidence for some proven relationships came from investigation of relatively small numbers of children with high-dose prenatal or early childhood exposures, e.g., CH(3)Hg poisoning episodes in Japan and Iraq. In contrast, consensus on a causal relationship between incident asthma and ETS exposure came only recently after many studies and prolonged debate. There were many relationships supported by limited epidemiologic evidence, ranging from several studies with fairly consistent findings and evidence of dose-response relationships to those where 20 or more studies provided inconsistent or otherwise less than convincing evidence of an association. The latter included childhood cancer and parental or childhood exposures to pesticides. In most cases, relationships supported by inadequate epidemiologic evidence reflect scarcity of evidence as opposed to strong evidence of no effect. This summary points to three main needs: (1) Where relationships between child health and environmental exposures are supported by sufficient evidence of causal relationships, there is a need for (a) policies and programs to minimize population exposures and (b) population-based biomonitoring to track exposure levels, i.e., through ongoing or periodic surveys with measurements of contaminant levels in blood, urine and other samples. (2) For relationships supported by limited evidence, there is a need for targeted research and policy options ranging from ongoing evaluation of evidence to proactive actions. (3) There is a great need for population-based, multidisciplinary and collaborative research on the many relationships supported by inadequate evidence, as these represent major knowledge gaps. Expert groups faced with evaluating epidemiologic evidence of potential causal relationships repeatedly encounter problems in summarizing the available data. A major driver for undertaking such summaries is the need to compensate for the limited sample sizes of individual epidemiologic studies. Sample size limitations are major obstacles to exploration of prenatal, paternal, and childhood exposures during specific time windows, exposure intensity, exposure-exposure or exposure-gene interactions, and relatively rare health outcomes such as childhood cancer. Such research needs call for investments in research infrastructure, including human resources and methods development (standardized protocols, biomarker research, validated exposure metrics, reference analytic laboratories). These are needed to generate research findings that can be compared and subjected to pooled analyses aimed at knowledge synthesis.
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Affiliation(s)
- Donald T Wigle
- McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada.
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Fox DA, Kala SV, Hamilton WR, Johnson JE, O'Callaghan JP. Low-level human equivalent gestational lead exposure produces supernormal scotopic electroretinograms, increased retinal neurogenesis, and decreased retinal dopamine utilization in rats. ENVIRONMENTAL HEALTH PERSPECTIVES 2008; 116:618-25. [PMID: 18470321 PMCID: PMC2367685 DOI: 10.1289/ehp.11268] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Accepted: 02/21/2008] [Indexed: 05/18/2023]
Abstract
BACKGROUND Postnatal lead exposure in children and animals produces alterations in the visual system primarily characterized by decreases in the rod-mediated (scotopic) electroretinogram (ERG) amplitude (subnormality). In contrast, low-level gestational Pb exposure (GLE) increases the amplitude of scotopic ERGs in children (supernormality). OBJECTIVES The goal of this study was to establish a rat model of human equivalent GLE and to determine dose-response effects on scotopic ERGs and on retinal morphology, biochemistry, and dopamine metabolism in adult offspring. METHODS We exposed female Long-Evans hooded rats to water containing 0, 27 (low), 55 (moderate), or 109 (high) ppm of Pb beginning 2 weeks before mating, throughout gestation, and until postnatal day (PND) 10. We measured maternal and litter indices, blood Pb concentrations (BPb), retinal Pb concentrations, zinc concentrations, and body weights. On PND90, we performed the retinal experiments. RESULTS Peak BPb concentrations were < 1, 12, 24, and 46 microg/dL in control, low-, moderate- and high-level GLE groups, respectively, at PNDs 0-10. ERG supernormality and an increased rod photoreceptor and rod bipolar cell neurogenesis occurred with low- and moderate-level GLE. In contrast, high-level GLE produced ERG subnormality, rod cell loss, and decreased retinal Zn levels. GLE produced dose-dependent decreases in dopamine and its utilization. CONCLUSIONS Low- and moderate-level GLE produced persistent scotopic ERG supernormality due to an increased neurogenesis of cells in the rod signaling pathway and/or decreased dopamine utilization, whereas high-level GLE produced rod-selective toxicity characterized by ERG subnormality. The ERG is a differential and noninvasive biomarker of GLE. The inverted U-shaped dose-response curves reveal the sensitivity and vulnerability of the developing retina to GLE.
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Affiliation(s)
- Donald A Fox
- College of Optometry, University of Houston, 4901 Calhoun Rd., Houston, TX 77204-2020, USA.
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22
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Barboni MTS, da Costa MF, Moura ALDA, Feitosa-Santana C, Gualtieri M, Lago M, Medrado-Faria MDA, Silveira LCDL, Ventura DF. Visual field losses in workers exposed to mercury vapor. ENVIRONMENTAL RESEARCH 2008; 107:124-31. [PMID: 17719027 DOI: 10.1016/j.envres.2007.07.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 04/29/2007] [Accepted: 07/09/2007] [Indexed: 05/16/2023]
Abstract
Visual field losses associated with mercury (Hg) exposure have only been assessed in patients exposed to methylmercury. Here we evaluate the automated visual field in 35 ex-workers (30 males; 44.20+/-5.92 years) occupationaly exposed to mercury vapor and 34 controls (21 males; 43.29+/-8.33 years). Visual fields were analyzed with the Humphrey Field Analyzer II (model 750i) using two tests: the standard automated perimetry (SAP, white-on-white) and the short wavelength automated perimetry (SWAP, blue-on-yellow) at 76 locations within a 27 degrees central visual field. Results were analyzed as the mean of the sensitivities measured at the fovea, and at five successive concentric rings, of increasing eccentricity, within the central field. Compared to controls, visual field sensitivities of the experimental group measured using SAP were lower for the fovea as well as for all five eccentricity rings (p<0.05). Sensitivities were significantly lower in the SWAP test (p<0.05) for four of the five extra-foveal eccentricity rings; they were not significant for the fovea (p=0.584) or for the 15 degrees eccentricity ring (p=0.965). These results suggest a widespread reduction of sensitivity in both visual field tests. Previous reports in the literature describe moderate to severe concentric constriction of the visual field in subjects with methylmercury intoxication measured manually with the Goldman perimeter. The present results amplify concerns regarding potential medical risks of exposure to environmental mercury sources by demonstrating significant and widespread reductions of visual sensitivity using the more reliable automated perimetry.
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23
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Bellinger DC, Daniel D, Trachtenberg F, Tavares M, McKinlay S. Dental amalgam restorations and children's neuropsychological function: the New England Children's Amalgam Trial. ENVIRONMENTAL HEALTH PERSPECTIVES 2007; 115:440-6. [PMID: 17431496 PMCID: PMC1849920 DOI: 10.1289/ehp.9497] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2006] [Accepted: 10/30/2006] [Indexed: 05/14/2023]
Abstract
BACKGROUND A concern persists that children's exposure to mercury vapor from dental amalgams produces neurotoxicity. OBJECTIVE Our goal was to compare the neuropsychological function of children, without prior exposure to dental amalgam, whose caries were repaired using either dental amalgam or mercury-free composite materials. METHODS We conducted a randomized controlled trial involving 534 6- to 10-year-old urban and rural children who were assessed yearly for 5 years using a battery of tests of intelligence, achievement, language, memory, learning, visual-spatial skills, verbal fluency, fine motor function, problem solving, attention, and executive function. RESULTS Although the mean urinary mercury concentration was greater among children in the amalgam group than the composite group (0.9 vs. 0.6 microg/g creatinine), few significant differences were found between the test scores of children in the two groups. The differences found were inconsistent in direction. Analyses using two cumulative exposure indices--surface years of amalgam and urinary mercury concentration--produced similar results. CONCLUSIONS Exposure to elemental mercury in amalgam at the levels experienced by the children who participated in the trial did not result in significant effects on neuropsychological function within the 5-year follow-up period.
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Affiliation(s)
- David C. Bellinger
- Department of Neurology, Children’s Hospital Boston and Harvard Medical School and
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
| | - David Daniel
- Department of Psychology, University of Maine at Farmington, Farmington, Maine, USA
| | | | - Mary Tavares
- The Forsyth Institute, Boston, Massachusetts, USA
| | - Sonja McKinlay
- New England Research Institutes, Watertown, Massachusetts, USA
- Address correspondence to S. McKinlay, New England Research Institutes, 9 Galen St., Watertown, MA 02472 USA. Telephone: (617) 923-7747. Fax: (617) 926-0144. E-mail:
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24
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From Animals to Humans: Models and Constructs. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0074-7750(05)30010-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Abstract
The effect of industrial chemicals on the sensory perception of exposed workers has received scant attention from the medical community to date, and the scientific literature is mainly limited to some case-reports or isolated studies. Possible explanations for this include the complexity of sensory perception, and the lack of agreement among researchers on methods for testing large groups of subjects. Nevertheless, some published studies showed that vision, hearing and olfactory function can be affected by various industrial metals and solvents, and some data exist also for touch and taste. This review discusses the main industrial chemicals involved. The pathogenesis of the toxicity of chemicals to sensory perception may be related to an action on receptors, nerve fibers, and/or the brain; probably, different pathogenetic mechanisms are involved. One of the main problems in this research field is that most of the studies to date evaluated the effect of a single industrial chemical on a single sense: as an example, we know that styrene exposure can impair smell and also hearing and vision but we have little idea whether different senses are impaired in the same worker, or whether each impairment is independent. In addition, workers are frequently exposed to different chemicals: co-exposure may have no effect, or result in both an increase or a decrease of the effect, as was observed for hearing loss, but studies on this aspect are largely insufficient. Research shows that both occupational and environmental exposure to industrial chemicals can affect sense organs, and suggests that the decline of perception with age may be, at least partly, related to this exposure. Nevertheless, available evidence is incomplete, and is largely inadequate for an estimation of a "safe" threshold of exposure. Good quality further research in this field is needed. This is certainly complex and demands adequate resources, but is justified by the ultimate result: the possibility to prevent an avoidable part of the decline in sensory function with age.
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Affiliation(s)
- Fabriziomaria Gobba
- Cattedra di Medicina del Lavoro, Dipartimento di Scienze Igienistiche, Università di Modena e Reggio Emilia, 41100 (MO) Modena, Italy.
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26
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Hirsch HVB, Mercer J, Sambaziotis H, Huber M, Stark DT, Torno-Morley T, Hollocher K, Ghiradella H, Ruden DM. Behavioral effects of chronic exposure to low levels of lead in Drosophila melanogaster. Neurotoxicology 2003; 24:435-42. [PMID: 12782108 DOI: 10.1016/s0161-813x(03)00021-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Through human activity lead has become a serious environmental neurotoxin, known to affect activity levels, attention and both sensory and cognitive function in children. Study of lead would be facilitated by having a model system that could be manipulated easily and quickly. We find Drosophila melanogaster ideal as such, and we have been studying effects of lead on courtship, fecundity and locomotor activity. We raised Canton-S flies from eggs to adult day 6-7 on medium made with lead acetate solution (2-100 microgram/g), or with distilled water, and we measured adult body lead burdens by means of Inductively Coupled Plasma Mass Spectrometry (ICP-MS). To measure courtship effectiveness, five virgin females and five virgin males were transferred into an empty vial and the number of females that mated within 20min was recorded. To measure fecundity, all adult offspring from eggs produced by one female within 12 days of mating were counted. To measure locomotor activity, individual flies were transferred to a grid-labeled petri dish and the number of lines crossed in 30s was counted. The number of females mating within 20min was increased significantly by exposure to 2 or 8 microgram/g lead, and was decreased significantly by exposure to 20 or 50 microgram/g lead. Fecundity was increased significantly by exposure to 2 microgram/g lead, but was unaffected by exposure to 20 microgram/g lead. Locomotor activity was consistently higher for males than for females, and was significantly reduced only by exposure to 50 microgram/g lead, and then only for males. We thus defined for Drosophila a lowest observable effect level (LOEL) of 2 microgram/g lead, which is considerably lower than the doses shown previously to affect this animal. The dose-response curve was biphasic for the number of females mating within 20min, an example of hormesis, a non-linear response that has been reported for low levels of stressors as diverse as pollutants and radiation. We hope from further studies with Drosophila to understand better how lead affects the developing nervous system, and thus ultimately its effects on children.
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Affiliation(s)
- Helmut V B Hirsch
- Department of Biology, The University at Albany, SUNY, 1400 Washington Avenue, 12222, Albany, NY, USA
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27
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Wilhelm M, Wittsiepe J, Schrey P, Feldmann C, Idel H. Dietary intake of lead by children and adults from Germany measured by the duplicate method. Int J Hyg Environ Health 2003; 206:493-503. [PMID: 14626897 DOI: 10.1078/1438-4639-00256] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The dietary lead intake was studied among children and adults from Germany. Two different age groups of children (A: 1.8, 1.3-3.0 years, B: 3.8, 1.8-5.2 years) and one group of adults (D: 40.9, 24-64 years) were from the highly industrialized Ruhr district and one group of children from the North Sea island Amrum (C: 3.9, 1.5-5.3 years). A total of 229 duplicate food portions were collected from 49 individuals between December 1994 and May 1995. Sampling period for each participant was either 3 (groups B and D) or 7 days (groups A and C). Lead levels in duplicate samples were measured by electrothermal atomic absorption spectrometry. The lead intakes (median, range) for the different groups were as follows: Group A: 0.21 (0.05-1.5) microgram/(kg bw.day), group B: 0.68 (0.06-1.6) microgram/(kg bw.day), group C: 0.29 (0.04-1.6) microgram/(kg bw.day) and group D: 0.26 (0.07-0.83) microgram/(kg bw.day). No value exceeded the provisional tolerable weekly intake (PTWI) of 25 micrograms/(kg bw.week) proposed by the WHO. The median and maximum of the different groups amounted to 7.2-16% and 16-36% of the PTWI, respectively. It is concluded that health risks due to dietary lead intake seem to be low in Germany.
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Affiliation(s)
- Michael Wilhelm
- Department of Hygiene, Social and Environmental Medicine, Ruhr-University Bochum, Universitätsstr. 150, D-44801 Bochum, Germany.
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28
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Morley EJ, Hirsch HVB, Hollocher K, Lnenicka GA. Effects of chronic lead exposure on the neuromuscular junction in Drosophila larvae. Neurotoxicology 2003; 24:35-41. [PMID: 12564380 DOI: 10.1016/s0161-813x(02)00095-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Long term or chronic exposure to lead is associated with cognitive and other deficits in humans, which may reflect lead-induced changes in synaptic development and function. We believe that Drosophila has great potential as a model system for studying such changes. To test this, we compared the structure of single, identified synapses between identified axons (axons 1 and 2) and muscle fibers (fibers 6 and 7) in untreated 3rd instar larvae, and in larvae reared on medium made with 100 microM lead acetate in distilled water. We used three approaches to examine the motor terminals on muscle fibers 6 and 7 in segment 2: (1) all terminals were stained with an antibody to HRP; (2) only the terminals of axon 1 were stained by injecting biotinylated Lucifer yellow into it; and (3) the regions of the terminal containing synaptic vesicles were stained with an antibody to synaptotagmin, which provides an estimate of "synaptic" terminal area. Lead burdens were determined by inductively coupled plasma mass spectrometry; hemolymph lead levels at the neuromuscular junction were likely to be micromolar. We observed that lead exposure did not significantly affect the average terminal area or the average muscle fiber area, but did significantly affect the uniformity of the matching between muscle area and motor terminal size that normally occurs during development. There was a significant positive correlation between motor terminal size and muscle area in control, but not in lead-exposed larvae. The sensitivity of Drosophila larval synaptic development to lead opens the way to using the powerful genetic and molecular tools available for this system to study the underlying mechanisms of this sensitivity. We would hope that from such an understanding may come strategies for dealing with lead-induced deficits in children.
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Affiliation(s)
- Eric J Morley
- Department of Biological Sciences, University at Albany, SUNY, Albany, NY 12222, USA
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29
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Wilhelm M, Pesch A, Rostek U, Begerow J, Schmitz N, Idel H, Ranft U. Concentrations of lead in blood, hair and saliva of German children living in three different areas of traffic density. THE SCIENCE OF THE TOTAL ENVIRONMENT 2002; 297:109-18. [PMID: 12389783 DOI: 10.1016/s0048-9697(02)00101-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Lead contents in hair, whole blood and saliva were determined for 245 healthy children (121 male, 124 female, age: 8-10 years) from three residential areas of Düsseldorf (North-Rhine-Westphalia, Germany) with different traffic densities. The geometric mean for the lead content in hair was found to be 0.87 microg/g (range: 0.2-9.9 microg/g) for the entire test group. While the levels of lead in hair in the suburban population were significantly lower than in the two city centre populations, no significant difference concerning the lead content in hair could be detected in the latter. The geometric mean for lead concentration in whole blood amounted to 25.0 microg/l (range: 8.0-154 microg/l). There was no significant difference between the sub-groups. The lead concentrations found in saliva were rather low (range: < 1.5-47.0 microg/l). Of the values, 89% were below the detection limit of 1.5 microg/l. Due to reduced levels of lead in fuel, the present study exposes that the amount of lead in the children examined has further decreased compared to preceding surveys. The correlation between the lead content in hair and the road traffic density was not corroborated by the findings with regard to amounts of lead found in blood, indicating that residual lead from fuel does not result in a substantial burden of lead found in the whole body. In contrast to levels of lead found in blood, levels of lead found in hair may be influenced more by environmental conditions. Saliva is not a suitable material for biological monitoring with respect to lead exposure in children.
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Affiliation(s)
- M Wilhelm
- Institute of Hygiene, Social and Environmental Medicine, Ruhr-University, Bochum, Germany.
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30
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Grandjean P, White RF, Sullivan K, Debes F, Murata K, Otto DA, Weihe P. Impact of contrast sensitivity performance on visually presented neurobehavioral tests in mercury-exposed children. Neurotoxicol Teratol 2001; 23:141-6. [PMID: 11348831 DOI: 10.1016/s0892-0362(01)00134-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Presentation of neuropsychological tests on a computer screen may involve a visual challenge to the examinee. The possible need for adjustment for visual contrast sensitivity on test performance was therefore determined from data on 917 mercury-exposed children who were examined at age 7 years. Contrast sensitivity was found to be associated with performance on the computer-assisted Continuous Performance Test. However, it showed similar associations with performance on traditional pencil-and-paper tests, especially Bender Visual Motor Gestalt Test and Wechsler Intelligence Scale for Children-Revised (WISC-R) Block Designs. Contrast sensitivity was not associated with prenatal mercury exposure, and adjustment for visual function had only a negligible effect on the regression coefficients for mercury as predictor of neuropsychological deficits. The mercury-associated neurobehavioral deficits are therefore unlikely to be due to mercury-induced visual system dysfunction causing secondary deficits in cognitive domain testing. Visuospatial processing appears to be a determinant in contrast sensitivity performance, and careful consideration of whether to control for contrast sensitivity in future studies of neurotoxicant effects is therefore recommended.
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Affiliation(s)
- P Grandjean
- Institute of Public Health, University of Southern Denmark, DK-5000 Odense, Denmark.
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31
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Affiliation(s)
- P O Ozuah
- Albert Einstein College of Medicine, Bronx, New York, USA
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Al-Saleh I, Nester M, DeVol E, Shinwari N, Al-Shahria S. Determinants of blood lead levels in Saudi Arabian schoolgirls. INTERNATIONAL JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH 1999; 5:107-14. [PMID: 10330510 DOI: 10.1179/oeh.1999.5.2.107] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Blood lead levels were measured in 538 girls aged 6 to 12 years who attended primary public schools in Riyadh, Saudi Arabia. Of the 538 screened children, 24.4% had blood lead levels > or =10 microg/dL, the Centers for Disease Control's level of concern. Variation in the blood lead levels was investigated with respect to a number of risk factors. The main determinant of blood lead levels was the regional location of the school. Pupils who attended schools located in the Central region of Riyadh had significantly higher blood lead concentrations than did pupils who attended schools in the peripheral areas. This is most likely to be due to the heavy vehicular emissions in the Central region. Other variables such as low family income, grade, and application of kohl to the child's eyes and/or umbilicus at birth were also contributors to the blood lead levels. These observations emphasize the importance of health education programs to promote the reduction of lead exposure in the general population.
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Affiliation(s)
- I Al-Saleh
- Biological and Medical Research Department, King Faisal Specialist Hospital and Research Center, P.O. Box 3354, Riyadh, Saudi Arabia
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Walkowiak J, Altmann L, Krämer U, Sveinsson K, Turfeld M, Weishoff-Houben M, Winneke G. Cognitive and sensorimotor functions in 6-year-old children in relation to lead and mercury levels: adjustment for intelligence and contrast sensitivity in computerized testing. Neurotoxicol Teratol 1998; 20:511-21. [PMID: 9761589 DOI: 10.1016/s0892-0362(98)00010-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Within a larger environmental health screening program neurobehavioral measures were taken in 384 6-year-old children (mean age 74 months) in the cities of Leipzig, Gardelegen, and Duisburg. Lead concentrations in venous blood samples (PbB) and urinary mercury excretion in 24-h samples (HgU) were measured as markers of environmental exposure by electrothermal AAS. Dependent variables included two subtests from the WISC [vocabulary (V) and block design (BD)] as well as five tests from the NES2 [pattern comparison, pattern memory, tapping, simple reaction time, and the continuous performance test (CPT; child version)]. In addition, visual functions [visual acuity (TITMUS-test) and contrast sensitivity (FACT)] were tested as covariates. The overall average PbB (geometric mean) was 42.5 microg/l (upper 95% value = 89 microg/l). The overall average mercury excretion (HgU) was 0.16 microg/24 h. Whereas no significant or borderline associations between HgU and any of the target variables was found, significant negative associations were observed between PbB and verbal intelligence (WISC vocabulary but not WISC Block Design) and false-positive responses (false alarms), as well as false-negative responses (miss) in the CPT. Whereas parental education was the most important confounder for WISC performance, visual contrast sensitivity and computer familiarity also proved predictive for performance in several computer-based NES subtests. It is concluded that non-IQ measures, namely measures of sustained attention, are negatively affected in children with 95% of blood-lead levels below 90 microg/l, even after adjustment for intelligence and contrast sensitivity, whereas the causative role of lead in altering IQ functions remains somewhat equivocal, because important covariates could not be controlled for.
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Affiliation(s)
- J Walkowiak
- Division of Biological Psychology, Medical Institute of Environmental Hygiene at the Heinrich-Heine-University Düsseldorf, Germany
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