1
|
Bose R, Spulber S, Ceccatelli S. The Threat Posed by Environmental Contaminants on Neurodevelopment: What Can We Learn from Neural Stem Cells? Int J Mol Sci 2023; 24:ijms24054338. [PMID: 36901772 PMCID: PMC10002364 DOI: 10.3390/ijms24054338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 02/03/2023] [Accepted: 02/17/2023] [Indexed: 02/24/2023] Open
Abstract
Exposure to chemicals may pose a greater risk to vulnerable groups, including pregnant women, fetuses, and children, that may lead to diseases linked to the toxicants' target organs. Among chemical contaminants, methylmercury (MeHg), present in aquatic food, is one of the most harmful to the developing nervous system depending on time and level of exposure. Moreover, certain man-made PFAS, such as PFOS and PFOA, used in commercial and industrial products including liquid repellants for paper, packaging, textile, leather, and carpets, are developmental neurotoxicants. There is vast knowledge about the detrimental neurotoxic effects induced by high levels of exposure to these chemicals. Less is known about the consequences that low-level exposures may have on neurodevelopment, although an increasing number of studies link neurotoxic chemical exposures to neurodevelopmental disorders. Still, the mechanisms of toxicity are not identified. Here we review in vitro mechanistic studies using neural stem cells (NSCs) from rodents and humans to dissect the cellular and molecular processes changed by exposure to environmentally relevant levels of MeHg or PFOS/PFOA. All studies show that even low concentrations dysregulate critical neurodevelopmental steps supporting the idea that neurotoxic chemicals may play a role in the onset of neurodevelopmental disorders.
Collapse
|
2
|
Moxon M, Melching-Kollmuss S, Semino-Beninel G, Hill S. The Grouping of Chemicals with Effects on Reproduction and Development for the Purpose of Cumulative Risk Assessment in Europe. Reprod Toxicol 2022; 109:39-52. [DOI: 10.1016/j.reprotox.2022.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/17/2022] [Accepted: 02/22/2022] [Indexed: 11/25/2022]
|
3
|
Lee J, Choi SJ, Jeong JS, Kim SY, Lee SJ, Baek SK, Kwon N, Lee SH, Kim W, Cho JW, Koh EM, Lee K, Jeong EJ, Nam SY, Yu WJ. Adverse postnatal developmental effects in offspring from humidifier disinfectant biocide inhaled pregnant rats. CHEMOSPHERE 2022; 286:131636. [PMID: 34358894 DOI: 10.1016/j.chemosphere.2021.131636] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 07/19/2021] [Accepted: 07/20/2021] [Indexed: 06/13/2023]
Abstract
Inhalation exposure to polyhexamethylene guanidine phosphate (PHMG-P), one of the primary biocides used in humidifier disinfectants, caused a fatal pulmonary disease in Korea. Pregnant women were also exposed to PHMG-P, and subsequent studies showed that PHMG-P inhalation during pregnancy adversely affects their health and embryo-fetal development. However, the postnatal developmental effects after birth on prenatally PHMG-P-exposed offspring have not yet been investigated. Therefore, in this study, we aimed to examine the postnatal development of prenatally PHMG-P-exposed offspring. Pregnant rats (22 or 24 females per group) were exposed to PHMG-P during pregnancy in a whole-body inhalation chamber at the target concentrations of 0, 0.14, 1.60, and 3.20 mg/m3. After parturition, the prenatally exposed offspring were transferred to non-exposed surrogate mothers to minimize the secondary effects of severe maternal toxicities. Postnatal development of offspring was then examined with a modified extended one-generation reproductive toxicity study design. At 3.20 mg/m3 PHMG-P, increased perinatal death rates and decreased viability index (postnatal survival of offspring between birth and postnatal day 4) were observed. In addition, F1 offspring had lower body weight at birth that persisted throughout the study. PHMG-P-exposed pregnant rats also had severe systemic toxicities and increased gestation period. At 1.60 mg/m3 PHMG-P, a decreased viability index was also observed with systemic toxicities of PHMG-P-exposed pregnant rats. These results indicate that prenatal PHMG-P exposure adversely affects the offspring's future health and could be used for human risk assessment.
Collapse
Affiliation(s)
- Jinsoo Lee
- Developmental and Reproductive Toxicology Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea; College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Seong-Jin Choi
- Department of Chemical Assessment, Korea Environment Corporation, Incheon, Republic of Korea
| | - Ji-Seong Jeong
- Developmental and Reproductive Toxicology Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Sang Yun Kim
- Developmental and Reproductive Toxicology Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Seung-Jin Lee
- Developmental and Reproductive Toxicology Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Sang-Ki Baek
- Developmental and Reproductive Toxicology Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Nayun Kwon
- Developmental and Reproductive Toxicology Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Sang-Hyub Lee
- Department of Chemical Assessment, Korea Environment Corporation, Incheon, Republic of Korea
| | - Woojin Kim
- Toxicologic Pathology Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Jae-Woo Cho
- Toxicologic Pathology Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Eun Mi Koh
- Bioanalytical and Immunoanalytical Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Kyuhong Lee
- Inhalation Toxicology Research Group, Korea Institute of Toxicology, Jeongeup, Republic of Korea; Department of Human and Environmental Toxicology, University of Science & Technology, Daejeon, Republic of Korea
| | - Eun Ju Jeong
- Chemical Risk Assessment Research Committee, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | - Sang-Yoon Nam
- College of Veterinary Medicine, Chungbuk National University, Cheongju, Republic of Korea
| | - Wook-Joon Yu
- Developmental and Reproductive Toxicology Research Group, Korea Institute of Toxicology, Daejeon, Republic of Korea.
| |
Collapse
|
4
|
Integration of evidence to evaluate the potential for neurobehavioral effects following exposure to USFDA-approved food colors. Food Chem Toxicol 2021; 151:112097. [DOI: 10.1016/j.fct.2021.112097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 02/23/2021] [Accepted: 02/25/2021] [Indexed: 01/02/2023]
|
5
|
Gentry R, Rodricks J, Clewell H, Greene T, Chappell G, Lea I, Borghoff S, Yang C, Rathman J, Ribeiro JV, Hobocienski B, Mostrag A. RE: Response to the Office of Environmental Health Hazard Assessment on comments related to Gentry et al. (2021). Food Chem Toxicol 2021; 152:112202. [PMID: 33872725 DOI: 10.1016/j.fct.2021.112202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
6
|
Li AA, Sheets LP, Raffaele K, Moser V, Hofstra A, Hoberman A, Makris SL, Garman R, Bolon B, Kaufmann W, Auer R, Lau E, Vidmar T, Bowers WJ. Recommendations for harmonization of data collection and analysis of developmental neurotoxicity endpoints in regulatory guideline studies: Proceedings of workshops presented at Society of Toxicology and joint Teratology Society and Neurobehavioral Teratology Society meetings. Neurotoxicol Teratol 2017; 63:24-45. [PMID: 28757310 PMCID: PMC6634984 DOI: 10.1016/j.ntt.2017.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 07/24/2017] [Accepted: 07/26/2017] [Indexed: 11/20/2022]
Abstract
The potential for developmental neurotoxicity (DNT) of environmental chemicals may be evaluated using specific test guidelines from the US Environmental Protection Agency or the Organisation for Economic Cooperation and Development (OECD). These guidelines generate neurobehavioral, neuropathological, and morphometric data that are evaluated by regulatory agencies globally. Data from these DNT guideline studies, or the more recent OECD extended one-generation reproductive toxicity guideline, play a pivotal role in children's health risk assessment in different world areas. Data from the same study may be interpreted differently by regulatory authorities in different countries resulting in inconsistent evaluations that may lead to inconsistencies in risk assessment decisions internationally, resulting in regional differences in public health protection or in commercial trade barriers. These issues of data interpretation and reporting are also relevant to juvenile and pre-postnatal studies conducted more routinely for pharmaceuticals and veterinary medicines. There is a need for development of recommendations geared toward the operational needs of the regulatory scientific reviewers who apply these studies in risk assessments, as well as the scientists who generate DNT data sets. The workshops summarized here draw upon the experience of the authors representing government, industry, contract research organizations, and academia to discuss the scientific issues that have emerged from diverse regulatory evaluations. Although various regulatory bodies have different risk management decisions and labeling requirements that are difficult to harmonize, the workshops provided an opportunity to work toward more harmonized scientific approaches for evaluating DNT data within the context of different regulatory frameworks. Five speakers and their coauthors with neurotoxicology, neuropathology, and regulatory toxicology expertise discussed issues of variability, data reporting and analysis, and expectations in DNT data that are encountered by regulatory authorities. In addition, principles for harmonized evaluation of data were suggested using guideline DNT data as case studies.
Collapse
Affiliation(s)
| | | | | | - Virginia Moser
- US EPA National Health and Environmental Effects Research Laboratory, Office of Research and Development (NHEERL, ORD), USA
| | | | - Alan Hoberman
- Charles River Laboratories, Global Developmental, Reproductive and Juvenile Toxicology, USA.
| | - Susan L Makris
- US EPA National Center for Environmental Assessment, Office of Research and Development (NCEA ORD), USA.
| | | | | | | | - Roland Auer
- University of Saskatchewan, Department of Pathology, Canada.
| | | | | | - Wayne J Bowers
- Department of Neuroscience, Carleton University, Ontario, Canada
| |
Collapse
|
7
|
Ema M, Okuda H, Gamo M, Honda K. A review of reproductive and developmental toxicity of silver nanoparticles in laboratory animals. Reprod Toxicol 2017; 67:149-164. [PMID: 28088501 DOI: 10.1016/j.reprotox.2017.01.005] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 12/12/2016] [Accepted: 01/06/2017] [Indexed: 01/02/2023]
Abstract
We summarized significant effects reported in the literature on the reproductive and developmental toxicity of silver nanoparticles (AgNPs) in laboratory animals. AgNPs showed testicular/sperm toxicity in males and ovarian and embryonic toxicity in females. Maternal injection of AgNPs delayed physical development and impaired cognitive behavior in offspring. Ag was accumulated in the testes after administration of AgNPs. AgNPs were identified in the visceral yolk sac after administration during early gestation in mice. Radiolabeled AgNPs were detected in placenta, breast milk, and pre- and postnatal offspring after injection during late gestation in rats. Ag in the ionic form, and possibly also particles, was suggested to be bioavailable. Although this review provides initial information on the potential reproductive and developmental toxicity of AgNPs, data is still very limited. Further studies using state-of-the-art methodologies and the relevant routes and doses for human exposure are required.
Collapse
Affiliation(s)
- Makoto Ema
- Research Institute of Science for Safety and Sustainability, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
| | - Hirokazu Okuda
- Division of Experimental Toxicology, Japan Bioassay Research Center (JBRC), 2445 Hirasawa, Hadano, Kanagawa 257-0015, Japan
| | - Masashi Gamo
- Research Institute of Science for Safety and Sustainability, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Kazumasa Honda
- Research Institute of Science for Safety and Sustainability, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| |
Collapse
|
8
|
Beekhuijzen M, Barentsen H, Marsden E, Zmarowski A, Aujoulat M, Picut C, Sloter E. Implementing the extended one-generation reproductive toxicity study (EOGRTS): important points to consider. Crit Rev Toxicol 2016; 46:332-47. [DOI: 10.3109/10408444.2015.1137863] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
9
|
Sheets LP, Li AA, Minnema DJ, Collier RH, Creek MR, Peffer RC. A critical review of neonicotinoid insecticides for developmental neurotoxicity. Crit Rev Toxicol 2016; 46:153-90. [PMID: 26513508 PMCID: PMC4732412 DOI: 10.3109/10408444.2015.1090948] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/01/2015] [Accepted: 09/02/2015] [Indexed: 01/21/2023]
Abstract
A comprehensive review of published and previously unpublished studies was performed to evaluate the neonicotinoid insecticides for evidence of developmental neurotoxicity (DNT). These insecticides have favorable safety profiles, due to their preferential affinity for nicotinic receptor (nAChR) subtypes in insects, poor penetration of the mammalian blood-brain barrier, and low application rates. Nevertheless, examination of this issue is warranted, due to their insecticidal mode of action and potential exposure with agricultural and residential uses. This review identified in vitro, in vivo, and epidemiology studies in the literature and studies performed in rats in accordance with GLP standards and EPA guidelines with imidacloprid, acetamiprid, thiacloprid, clothianidin, thiamethoxam, and dinotefuran, which are all the neonicotinoids currently registered in major markets. For the guideline-based studies, treatment was administered via the diet or gavage to primiparous female rats at three dose levels, plus a vehicle control (≥20/dose level), from gestation day 0 or 6 to lactation day 21. F1 males and females were evaluated using measures of motor activity, acoustic startle response, cognition, brain morphometry, and neuropathology. The principal effects in F1 animals were associated with decreased body weight (delayed sexual maturation, decreased brain weight, and morphometric measurements) and acute toxicity (decreased activity during exposure) at high doses, without neuropathology or impaired cognition. No common effects were identified among the neonicotinoids that were consistent with DNT or the neurodevelopmental effects associated with nicotine. Findings at high doses were associated with evidence of systemic toxicity, which indicates that these insecticides do not selectively affect the developing nervous system.
Collapse
Affiliation(s)
| | - Abby A. Li
- Exponent Health Sciences,
San Francisco,
CA,
USA
| | | | | | | | | |
Collapse
|
10
|
Ema M, Hougaard KS, Kishimoto A, Honda K. Reproductive and developmental toxicity of carbon-based nanomaterials: A literature review. Nanotoxicology 2015; 10:391-412. [DOI: 10.3109/17435390.2015.1073811] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
11
|
Garman RH, Li AA, Kaufmann W, Auer RN, Bolon B. Recommended Methods for Brain Processing and Quantitative Analysis in Rodent Developmental Neurotoxicity Studies. Toxicol Pathol 2015; 44:14-42. [PMID: 26296631 DOI: 10.1177/0192623315596858] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Neuropathology methods in rodent developmental neurotoxicity (DNT) studies have evolved with experience and changing regulatory guidance. This article emphasizes principles and methods to promote more standardized DNT neuropathology evaluation, particularly procurement of highly homologous brain sections and collection of the most reproducible morphometric measurements. To minimize bias, brains from all animals at all dose levels should be processed from brain weighing through paraffin embedding at one time using a counterbalanced design. Morphometric measurements should be anchored by distinct neuroanatomic landmarks that can be identified reliably on the faced block or in unstained sections and which address the region-specific circuitry of the measured area. Common test article-related qualitative changes in the developing brain include abnormal cell numbers (yielding altered regional size), displaced cells (ectopia and heterotopia), and/or aberrant differentiation (indicated by defective myelination or synaptogenesis), but rarely glial or inflammatory reactions. Inclusion of digital images in the DNT pathology raw data provides confidence that the quantitative analysis was done on anatomically matched (i.e., highly homologous) sections. Interpreting DNT neuropathology data and their presumptive correlation with neurobehavioral data requires an integrative weight-of-evidence approach including consideration of maternal toxicity, body weight, brain weight, and the pattern of findings across brain regions, doses, sexes, and ages.
Collapse
Affiliation(s)
- Robert H Garman
- Consultants in Veterinary Pathology, Inc., Murrysville, Pennsylvania, USA
| | - Abby A Li
- Exponent Inc., San Francisco, California, USA
| | | | - Roland N Auer
- Hôpital Ste-Justine, Département de Pathologie, Université de Montréal, Québec, Canada
| | | |
Collapse
|
12
|
Fritsche E, Alm H, Baumann J, Geerts L, Håkansson H, Masjosthusmann S, Witters H. Literature review on in vitro and alternative Developmental Neurotoxicity (DNT) testing methods. ACTA ACUST UNITED AC 2015. [DOI: 10.2903/sp.efsa.2015.en-778] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ellen Fritsche
- Leibniz Research Institute for Environmental Medicine (IUF), Group of Sphere Models and Risk Assessment, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Henrik Alm
- Leibniz Research Institute for Environmental Medicine (IUF), Group of Sphere Models and Risk Assessment, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Jenny Baumann
- Leibniz Research Institute for Environmental Medicine (IUF), Group of Sphere Models and Risk Assessment, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Lieve Geerts
- Flemish Institute for Technological Research (VITO), Environmental Risk & Health, Boeretang 200, B‐2400 Mol, Belgium
| | - Helen Håkansson
- Karolinska Institute (KI), Institute of Environmental Medicine (IMM), Unit of Environmental Health Risk Assessment, SE‐171 77 Stockholm, Sweden
| | - Stefan Masjosthusmann
- Leibniz Research Institute for Environmental Medicine (IUF), Group of Sphere Models and Risk Assessment, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany
| | - Hilda Witters
- Flemish Institute for Technological Research (VITO), Environmental Risk & Health, Boeretang 200, B‐2400 Mol, Belgium
| |
Collapse
|
13
|
Smirnova L, Hogberg HT, Leist M, Hartung T. Developmental neurotoxicity - challenges in the 21st century and in vitro opportunities. ALTEX-ALTERNATIVES TO ANIMAL EXPERIMENTATION 2015; 31:129-56. [PMID: 24687333 DOI: 10.14573/altex.1403271] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 03/28/2014] [Indexed: 11/23/2022]
Abstract
In recent years neurodevelopmental problems in children have increased at a rate that suggests lifestyle factors and chemical exposures as likely contributors. When environmental chemicals contribute to neurodevelopmental disorders developmental neurotoxicity (DNT) becomes an enormous concern. But how can it be tackled? Current animal test- based guidelines are prohibitively expensive, at $ 1.4 million per substance, while their predictivity for human health effects may be limited, and mechanistic data that would help species extrapolation are not available. A broader screening for substances of concern requires a reliable testing strategy, applicable to larger numbers of substances, and sufficiently predictive to warrant further testing. This review discusses the evidence for possible contributions of environmental chemicals to DNT, limitations of the current test paradigm, emerging concepts and technologies pertinent to in vitro DNT testing and assay evaluation, as well as the prospect of a paradigm shift based on 21st century technologies.
Collapse
Affiliation(s)
- Lena Smirnova
- Centers for Alternatives to Animal Testing (CAAT) at Johns Hopkins Bloomberg School of Public Health, USA
| | | | | | | |
Collapse
|
14
|
Developmental Neurotoxicology: History and Outline of Developmental Neurotoxicity Study Guidelines. Food Saf (Tokyo) 2015. [DOI: 10.14252/foodsafetyfscj.2015012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
15
|
Neal-Kluever A, Aungst J, Gu Y, Hatwell K, Muldoon-Jacobs K, Liem A, Ogungbesan A, Shackelford M. Infant toxicology: State of the science and considerations in evaluation of safety. Food Chem Toxicol 2014; 70:68-83. [DOI: 10.1016/j.fct.2014.05.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 05/02/2014] [Accepted: 05/03/2014] [Indexed: 11/26/2022]
|
16
|
Scientific Opinion on the developmental neurotoxicity potential of acetamiprid and imidacloprid. EFSA J 2013. [DOI: 10.2903/j.efsa.2013.3471] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
|
17
|
Tsuji R, Crofton KM. Developmental neurotoxicity guideline study: issues with methodology, evaluation and regulation. Congenit Anom (Kyoto) 2012; 52:122-8. [PMID: 22925212 DOI: 10.1111/j.1741-4520.2012.00374.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Recently social concerns have been increasing about the effects of environmental factors on children's health, especially on their nervous systems. The U.S. Environmental Protection Agency (EPA) and the Organisation for Economic Co-operation and Development (OECD) have published testing guidelines for developmental neurotoxicity (DNT). Approximately 110 guideline studies have been conducted to date. Importantly, information from these studies has provided data critical for regulatory decisions for a number of chemicals. However, the DNT guidelines do not always satisfy all stakeholders because of some uncertainties in their methodology, evaluation, and regulation. Methodological issues include incomplete harmonization between EPA and OECD guidelines, criticisms of the methodology for learning and memory testing, and unspecified positive control substances. Potential artifacts in morphometric neuropathological measures, criteria for observation measures, uncertainty of postnatal offspring exposure, especially in feeding studies, and extrapolation of data from rats to humans are major evaluation issues. In addition, there is some uncertainty in the use of an additional safety factor for susceptibility of infants and children. Moreover, the DNT guidelines have extensive time and cost requirements, use large numbers of animals, and there is a limited set of laboratories that can conduct the study. This paper reviews some of these issues and summarizes discussions from the symposium 'Developmental neurotoxicity testing: Scientific approaches towards the next generation to protecting the developing nervous system of children' held at the 2011 annual meeting of the Japanese Teratology Society.
Collapse
Affiliation(s)
- Ryozo Tsuji
- Environmental Health Science Laboratory, Sumitomo Chemical Co. Ltd, Osaka, Japan.
| | | |
Collapse
|
18
|
London L, Beseler C, Bouchard MF, Bellinger DC, Colosio C, Grandjean P, Harari R, Kootbodien T, Kromhout H, Little F, Meijster T, Moretto A, Rohlman DS, Stallones L. Neurobehavioral and neurodevelopmental effects of pesticide exposures. Neurotoxicology 2012; 33:887-96. [PMID: 22269431 DOI: 10.1016/j.neuro.2012.01.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 01/06/2012] [Accepted: 01/09/2012] [Indexed: 11/28/2022]
Abstract
The association between pesticide exposure and neurobehavioral and neurodevelopmental effects is an area of increasing concern. This symposium brought together participants to explore the neurotoxic effects of pesticides across the lifespan. Endpoints examined included neurobehavioral, affective and neurodevelopmental outcomes among occupational (both adolescent and adult workers) and non-occupational populations (children). The symposium discussion highlighted many challenges for researchers concerned with the prevention of neurotoxic illness due to pesticides and generated a number of directions for further research and policy interventions for the protection of human health, highlighting the importance of examining potential long-term effects across the lifespan arising from early adolescent, childhood or prenatal exposure.
Collapse
Affiliation(s)
- Leslie London
- Centre for Occupational and Environmetal Health Research, School of Public Health and Family Medicine, University of Cape Town, South Africa
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Adams J. The neurobehavioral teratology of retinoids: a 50-year history. ACTA ACUST UNITED AC 2011; 88:895-905. [PMID: 20865785 DOI: 10.1002/bdra.20721] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This review of the central nervous system (CNS) and behavioral teratology of the retinoids over the last 50 years is a commemorative retrospective organized by decade to show the prominent research focus within each period and the most salient findings. In the 1960s, research focused on the gross CNS malformations associated with exposure and the delineation of dose-response and stage-specific responses in rodent models. Relevant scientific events before and during the 1960s are also discussed to provide the zeitgeist in which the field of neurobehavioral teratology emerged in the 1970s. During this period, studies demonstrated that adverse effects on postnatal behavior could be produced in animals exposed to doses of vitamin A lower than those that were teratogenic or impacted growth. Work during the 1980s showed an overrepresentation of behavioral studies focused on the reliability of screening methods, while the marked effects of human exposure were illustrated in children born to women treated with isotretinoin during pregnancy. The human catastrophe invigorated research during the 1990s, a period when technological advances allowed more elegant examinations of the developing CNS, of biochemical, cellular, and molecular developmental events and regulatory actions, and of the effects of direct genetic manipulations. Likewise, research in the 1990s reflected a reinvigoration of research in neurobehavioral teratology evinced in studies that used animal models to try to better understand human vulnerability. These foci continued in the 2000-2010 period while examinations of the role of retinoids in brain development and lifelong functioning became increasingly sophisticated and broader in scope. This review of the work on retinoids also provides a lens on the more general ontogeny of the field of neurobehavioral teratology. Birth Defects Research (Part A), 2010. © 2010 Wiley-Liss, Inc.
Collapse
Affiliation(s)
- Jane Adams
- Department of Psychology, University of Massachusetts-Boston, 100 Morrissey Boulevard, Boston, MA 02125, USA.
| |
Collapse
|
20
|
Stump DG, Beck MJ, Radovsky A, Garman RH, Freshwater LL, Sheets LP, Marty MS, Waechter JM, Dimond SS, Van Miller JP, Shiotsuka RN, Beyer D, Chappelle AH, Hentges SG. Developmental neurotoxicity study of dietary bisphenol A in Sprague-Dawley rats. Toxicol Sci 2010; 115:167-82. [PMID: 20164145 PMCID: PMC2855351 DOI: 10.1093/toxsci/kfq025] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Accepted: 01/22/2010] [Indexed: 11/13/2022] Open
Abstract
This study was conducted to determine the potential of bisphenol A (BPA) to induce functional and/or morphological effects to the nervous system of F(1) offspring from dietary exposure during gestation and lactation according to the Organization for Economic Cooperation and Development and U.S. Environmental Protection Agency guidelines for the study of developmental neurotoxicity. BPA was offered to female Sprague-Dawley Crl:CD (SD) rats (24 per dose group) and their litters at dietary concentrations of 0 (control), 0.15, 1.5, 75, 750, and 2250 ppm daily from gestation day 0 through lactation day 21. F(1) offspring were evaluated using the following tests: detailed clinical observations (postnatal days [PNDs] 4, 11, 21, 35, 45, and 60), auditory startle (PNDs 20 and 60), motor activity (PNDs 13, 17, 21, and 61), learning and memory using the Biel water maze (PNDs 22 and 62), and brain and nervous system neuropathology and brain morphometry (PNDs 21 and 72). For F(1) offspring, there were no treatment-related neurobehavioral effects, nor was there evidence of neuropathology or effects on brain morphometry. Based on maternal and offspring body weight reductions, the no-observed-adverse-effect level (NOAEL) for systemic toxicity was 75 ppm (5.85 and 13.1 mg/kg/day during gestation and lactation, respectively), with no treatment-related effects at lower doses or nonmonotonic dose responses observed for any parameter. There was no evidence that BPA is a developmental neurotoxicant in rats, and the NOAEL for developmental neurotoxicity was 2250 ppm, the highest dose tested (164 and 410 mg/kg/day during gestation and lactation, respectively).
Collapse
Affiliation(s)
- Donald G Stump
- Developmental and Reproductive Toxicology, WIL Research Laboratories, LLC, Ashland, Ohio 44805-8946, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Raffaele KC, Rowland J, May B, Makris SL, Schumacher K, Scarano LJ. The use of developmental neurotoxicity data in pesticide risk assessments. Neurotoxicol Teratol 2010; 32:563-72. [PMID: 20398750 DOI: 10.1016/j.ntt.2010.04.053] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 01/29/2010] [Accepted: 02/03/2010] [Indexed: 10/19/2022]
Abstract
Following the passage of the Food Quality Protection Act, which mandated an increased focus on evaluating the potential toxicity of pesticides to children, the number of guideline developmental neurotoxicity (DNT) studies (OPPTS 870.6300) submitted to the U.S. Environmental Protection Agency (EPA) Office of Pesticide Programs (OPP) was greatly increased. To evaluate the impact of available DNT studies on individual chemical risk assessments, the ways in which data from these studies are being used in pesticide risk assessment were investigated. In addition, the neurobehavioral and neuropathological parameters affected at the lowest observed adverse effect level (LOAEL) for each study were evaluated to ascertain whether some types of endpoints were consistently more sensitive than others. As of December 2008, final OPP reviews of DNT studies for 72 pesticide chemicals were available; elimination of studies with major deficiencies resulted in a total of 69 that were included in this analysis. Of those studies, 15 had been used to determine the point of departure for one or more risk assessment scenarios, and an additional 13 were determined to have the potential for use as a point of departure for future risk assessments (selection is dependent upon review of the entire database available at the time of reassessment). Analysis of parameters affected at the study LOAELs indicated that no single parameter was consistently more sensitive than another. Early assessment time points (e.g., postnatal day (PND) 11/21) tended to be more sensitive than later time points (e.g., PND 60). These results demonstrate that data generated using the current guideline DNT study protocol are useful in providing points of departure for risk assessments. The results of these studies also affirm the importance of evaluating a spectrum of behavioral and neuropathological endpoints, in both young and adult animals, to improve the detection of the potential for a chemical to cause developmental neurotoxicity.
Collapse
Affiliation(s)
- Kathleen C Raffaele
- Office of Research and Development, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., Washington, DC 20460, USA.
| | | | | | | | | | | |
Collapse
|
22
|
Abstract
PURPOSE OF REVIEW Summarize recent studies exploring the relationship between paternal and maternal environmental exposures to chemicals before, at the time of and after conception to adverse developmental outcomes including preterm birth, death, structural and functional abnormalities and growth restriction. RECENT FINDINGS Recent studies have demonstrated that human pregnancy and development are vulnerable to environmental exposures of the father and mother to chemical, biological and physical agents. Exposures associated with adverse developmental outcomes include air and water pollution, chemicals in foods, occupational exposures, agricultural chemicals, metals, persistent and volatile organics. Developmental endpoints which are linked with these exposures include growth restriction, functional abnormalities, structural abnormalities, preterm delivery and death. Despite this general understanding we still have incomplete knowledge concerning most exposures and the biological interactions responsible for impaired development and preterm delivery. SUMMARY Whereas single genes and individual chemical exposures are responsible for some instances of adverse pregnancy outcome or developmental disease, gene-environment interactions are responsible for the majority. These gene-environment interactions may occur in the father, mother, placenta or fetus, suggesting that critical attention be given to maternal and paternal exposures and gene expression as they relate to the mode of action of the putative developmental toxicant both prior to and during pregnancy.
Collapse
|
23
|
Maurissen J. Practical considerations on the design, execution and analysis of developmental neurotoxicity studies to be published in Neurotoxicology and Teratology. Neurotoxicol Teratol 2010; 32:121-3. [DOI: 10.1016/j.ntt.2009.09.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 08/12/2009] [Accepted: 09/09/2009] [Indexed: 11/29/2022]
|
24
|
Bailey GP, Wise LD, Buschmann J, Hurtt M, Fisher JE. Pre- and postnatal developmental toxicity study design for pharmaceuticals. ACTA ACUST UNITED AC 2009; 86:437-45. [DOI: 10.1002/bdrb.20217] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
25
|
DeSesso JM, Watson RE, Keen CL, Hazelden KP, Haws LC, Li AA. Analysis and integration of developmental neurotoxicity and ancillary data into risk assessment: a case study of dimethoate. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2009; 72:94-109. [PMID: 19034799 DOI: 10.1080/15287390802477452] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Dimethoate is an organophosphate (OP) pesticide used to control a wide variety of insects on agricultural crops and ornamentals. To ensure that dimethoate is used safely, it is important to determine exposure levels that protect against adverse effects at all life stages, including the developing fetus, infant, and child. Based on an analysis of a developmental neurotoxicity (DNT) study, a cholinesterase (ChE) sensitivity study, a cross-fostering study, and several single- and multigenerational reproductive toxicity studies, two potential critical endpoints for dimethoate were identified: brain ChE inhibition (ChEI) in adult females, and pup mortality. An initial evaluation concluded that pup mortality was a preferable endpoint, based on an increased number of pup deaths born to dams dosed with > or =3 mg/kg dimethoate via oral gavage. Closer examination, however, revealed that the pup deaths were clustered in a small number of litters in which the dams providing postnatal care exhibited maternal care deficits. When the data were analyzed using the dam as the unit of statistical significance, a significant increase in the average litter proportion of pup deaths was observed only when the dams were dosed postnatally with 6 mg/kg dimethoate while they were raising the pups. Gestational exposure (i.e., during pregnancy only) to 6 mg/kg dimethoate exerted no effect on pup survival. This leads to the conclusion that it is postnatal exposure of the nursing dams that is associated with pup mortality. Furthermore, a previous benchmark dose (BMD) meta-analysis approach revealed that BMDL(10) for adult females (the lower 95% bound of the dose resulting in a 10% reduction in the parameter of interest) for ChEI was > 3-fold lower than the BMDL(10) for pup mortality (0.19 and 0.68 mg/kg, respectively). Overall, this study underscores the importance of using the dam as the unit of statistical significance when assessing data collected in the perinatal period, and it is concluded that adult brain ChEI is the correct critical endpoint for assessing risk of dimethoate toxicity.
Collapse
|
26
|
Makris SL, Raffaele K, Allen S, Bowers WJ, Hass U, Alleva E, Calamandrei G, Sheets L, Amcoff P, Delrue N, Crofton KM. A retrospective performance assessment of the developmental neurotoxicity study in support of OECD test guideline 426. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:17-25. [PMID: 19165382 PMCID: PMC2627860 DOI: 10.1289/ehp.11447] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Accepted: 08/12/2008] [Indexed: 05/04/2023]
Abstract
OBJECTIVE We conducted a review of the history and performance of developmental neurotoxicity (DNT) testing in support of the finalization and implementation of Organisation of Economic Co-operation and Development (OECD) DNT test guideline 426 (TG 426). INFORMATION SOURCES AND ANALYSIS In this review we summarize extensive scientific efforts that form the foundation for this testing paradigm, including basic neurotoxicology research, interlaboratory collaborative studies, expert workshops, and validation studies, and we address the relevance, applicability, and use of the DNT study in risk assessment. CONCLUSIONS The OECD DNT guideline represents the best available science for assessing the potential for DNT in human health risk assessment, and data generated with this protocol are relevant and reliable for the assessment of these end points. The test methods used have been subjected to an extensive history of international validation, peer review, and evaluation, which is contained in the public record. The reproducibility, reliability, and sensitivity of these methods have been demonstrated, using a wide variety of test substances, in accordance with OECD guidance on the validation and international acceptance of new or updated test methods for hazard characterization. Multiple independent, expert scientific peer reviews affirm these conclusions.
Collapse
Affiliation(s)
- Susan L Makris
- Office of Research and Development, National Center for Environmental Assessment, U.S Environmental Protection Agency, Washington, DC 20460-0001, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|