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Dórea JG. Neurodevelopment and exposure to neurotoxic metal(loid)s in environments polluted by mining, metal scrapping and smelters, and e-waste recycling in low and middle-income countries. ENVIRONMENTAL RESEARCH 2021; 197:111124. [PMID: 33861977 DOI: 10.1016/j.envres.2021.111124] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 04/01/2021] [Accepted: 04/01/2021] [Indexed: 06/12/2023]
Abstract
This review covers a wide body of literature to gain an understanding of the impacts of informal activities related to metal extraction (primary mining and recycling) on early life exposure to neurotoxicants and on neurodevelopment. In primary mining, gold extraction with Hg amalgamation is the main environmental cause of Hg pollution in most artisanal small-scale gold mining (ASGM) activities around the world. Nevertheless, in Sub-Saharan Africa (SSA), Pb disrupted from gold-related ores, mining, and artisanal cookware production are an important neurotoxicant that seriously contaminates the affected population, with devastating effects on children. In e-waste recycling settings, the range of neurotoxic substances that contaminate mothers and children is wider than in primary mining environments. Thus, Hg and Pb are major pre- and postnatal neurotoxicants affecting children in the informal metal extraction activities and SSA countries show the highest record of human contamination and of neurotoxic effects on children. There are additional sources of neurotoxic contamination from mining and metal processing activities (cyanide tailing in South America and SSA) and/or co-exposure to Hg-containing products such as cosmetics (soaps and Hg-based skin lightning creams in Africa) and pediatric Thimerosal-containing vaccines (TCVs, that breaks down to ethyl-mercury) in current use in middle and low income countries. However, the action of these neurotoxicants (per se or in combination) on children needs more attention and research. Studies show a negative association between biomarkers of all environmental metal(loid)s (As, Cd, Hg, Mn, and Pb) studied and neurodevelopment in young children. Sadly, in many unregulated activities, child labor is widely employed, thus presenting an additional occupational exposure. Children living in polluted environments related to metal processing are disproportionately exposed to a wide range of co-occurring neurotoxic substances. The review showed compelling evidence from highly representative parts of the world (Africa, Asia, and Latin America) that the studied neurotoxic substances negatively affected areas of the brain associated with language, memory and executive function, as well as psychosocial behavior. Protecting the environment and children from unregulated and highly polluting metal extraction and processing are inextricably intertwined and deserve urgent attention.
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Affiliation(s)
- José G Dórea
- Universidade de Brasília, Brasília, 70919-970, DF, Brazil.
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Trdin A, Falnoga I, Fajon V, Živković I, Snoj Tratnik J, Prpić I, Špirić Z, Horvat M. Mercury speciation in meconium and associated factors. ENVIRONMENTAL RESEARCH 2019; 179:108724. [PMID: 31627028 DOI: 10.1016/j.envres.2019.108724] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/21/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
Meconium is formed early in gestation and it is normally not excreted until after birth. Thus it may provide a longer and cumulative record of exposure to mercury (Hg). The present study aims to speciate Hg in meconium samples (N = 488) from Slovenian and Croatian new-borns prenatally exposed to low levels of methyl-Hg (MeHg) from maternal seafood intake and to Hg0 from maternal dental amalgam fillings. We had complete data of total Hg (THg) and MeHg in meconium and THg in maternal hair (MH), while THg and MeHg in maternal blood (MB) were available only for Croatian mothers. Personal data namely maternal seafood intake, age, pre-pregnancy BMI, parity, smoking, estimated gestational age at birth, sex, and birth weight were available for the majority of participants, except the number of dental amalgams which was in most cases missing for Croatian mothers. The median THg concentration in meconium was 11.1 (range: 0.41-375.2) ng/g and inorganic Hg (Hg(II)) presented 98.8% (range: 82%-100%, CV: 2%) of THg. We observed significant correlation between meconium and MH Hg levels, with the highest correlation between hair THg and meconium MeHg. Correlation analysis including MB (available only for Croatian population) showed a significant positive correlation between THg in meconium and THg in MB (Rs = 0.642). Additionally, MeHg from MB was correlated with MeHg in meconium (Rs = 0.898), while the correlation between Hg(II) in MB and meconium was positive, but not significant. Maternal seafood intake was significantly correlated with meconium MeHg (Rs = 0.498) and Hg(II) (Rs = 0.201). Multiple linear regression (performed on the Slovenian population, N = 143) confirmed a positive association between meconium MeHg and seafood intake. Furthermore, meconium Hg(II) was positively associated with the number of maternal dental amalgam fillings, but linear regression models did not confirm correlation between seafood intake and meconium Hg(II) levels. We assume that Hg0 released from maternal dental amalgam fillings and MeHg from seafood intake were both transported through the placental barrier and portioned between different foetal compartments including meconium. Weak correlation between maternal seafood intake and Hg(II) levels in meconium suggests that there is certain evidence of MeHg demethylation. However, because this correlation was not confirmed by the multiple regression, MeHg demethylation during prenatal life cannot be neither confirmed nor excluded. Further investigations at higher level of exposure are needed to confirm this observations. We can conclude that meconium is a suitable biomarker for MeHg and Hg0 exposure during pregnancy. However, comparability of the results reported in meconium in different studies is hindered by a lack of standardized sampling protocols, storage, and analysis.
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Affiliation(s)
- Ajda Trdin
- Department of Environmental Sciences, Jožef Stefan Institute, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Ingrid Falnoga
- Department of Environmental Sciences, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Vesna Fajon
- Department of Environmental Sciences, Jožef Stefan Institute, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Igor Živković
- Department of Environmental Sciences, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Janja Snoj Tratnik
- Department of Environmental Sciences, Jožef Stefan Institute, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Igor Prpić
- Department of Paediatrics, University Hospital Centre Rijeka, Rijeka, Croatia
| | | | - Milena Horvat
- Department of Environmental Sciences, Jožef Stefan Institute, Ljubljana, Slovenia; Jožef Stefan International Postgraduate School, Ljubljana, Slovenia.
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Tatsuta N, Nakai K, Sakamoto M, Murata K, Satoh H. Methylmercury Exposure and Developmental Outcomes in Tohoku Study of Child Development at 18 Months of Age. TOXICS 2018; 6:toxics6030049. [PMID: 30134554 PMCID: PMC6161177 DOI: 10.3390/toxics6030049] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 08/14/2018] [Accepted: 08/18/2018] [Indexed: 11/21/2022]
Abstract
Seafood is an important component in a healthy diet and may contain methylmercury or other contaminants. It is important to recognize the risks and benefits of consuming seafood. A longitudinal prospective birth cohort study has been conducted to clarify the effects of neurotoxicants on child development—the Tohoku Study of Child Development (TSCD) in Japan. TSCD comprises two cohorts; a polychlorinated biphenyls (PCB) cohort (urban area) and a methylmercury cohort (coastal area). Our previous results from the coastal area showed prenatal methylmercury exposure affected psychomotor development in 18-month-olds, and boys appear to be more vulnerable to the exposure than girls. In this report, we have added the urban area cohort and we reanalyzed the impact of prenatal exposure to methylmercury, which gave the same results as before. These findings suggest prenatal exposure to low levels methylmercury may have adverse effects on child development, especially in boys.
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Affiliation(s)
- Nozomi Tatsuta
- Development and Environmental Medicine, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
| | - Kunihiko Nakai
- Development and Environmental Medicine, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
| | - Mineshi Sakamoto
- Development and Environmental Medicine, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
- Environmental Health Section, Department of Environmental Science and Epidemiology, National Institute for Minamata Disease, Kumamoto 867-0008, Japan.
| | - Katsuyuki Murata
- Department of Environmental Health Sciences, Akita University Graduate School of Medicine, Akita 010-8502, Japan.
| | - Hiroshi Satoh
- Environmental Health Science, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan.
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Ou L, Wang H, Chen C, Chen L, Zhang W, Wang X. Physiologically based pharmacokinetic (PBPK) modeling of human lactational transfer of methylmercury in China. ENVIRONMENT INTERNATIONAL 2018; 115:180-187. [PMID: 29574338 DOI: 10.1016/j.envint.2018.03.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 03/13/2018] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
Methylmercury can readily cross the human placental barrier and the blood-brain barrier and cause damage to the vulnerable developing brains of the fetus and infants. Most of the previous studies on the maternal transfer of methylmercury to the next generation have focused on the prenatal period. In this study, human physiologically based pharmacokinetic (PBPK) models of methylmercury were established for breastfeeding mothers and suckling infants based on the existing model prototypes of previous studies. Relevant parameters of the models were modified, and the validation was conducted based on measured data in North China. The models could effectively describe the human lactational transfer of methylmercury, including the time-dependent methylmercury levels in different tissues and organs of the breastfeeding mothers and suckling infants. The results indicated that 77.2% and 14.9% of methylmercury were excreted via hair and breast milk, respectively, from breastfeeding mothers during the first year after delivery. Meanwhile, 79.2% was excreted from the suckling infants during the first year after delivery via hair. Lactational transfer of methylmercury was considered an important pathway of methylmercury exposure for the breastfeeding infants, which accounted for approximately 80% of the accumulated adverse impacts at the early stages of human development.
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Affiliation(s)
- Langbo Ou
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Huanhuan Wang
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Cen Chen
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Long Chen
- School of Geographic Sciences, East China Normal University, Shanghai 200241, China
| | - Wei Zhang
- School of Environment and Natural Resources, Renmin University of China, Beijing 100872, China.
| | - Xuejun Wang
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
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dos Santos Freitas J, da Costa Brito Lacerda EM, da Silva Martins ICV, Rodrigues D, Bonci DMO, Cortes MIT, Corvelo TCO, Ventura DF, de Lima Silveira LC, da Conceição Nascimento Pinheiro M, da Silva Souza G. Cross-sectional study to assess the association of color vision with mercury hair concentration in children from Brazilian Amazonian riverine communities. Neurotoxicology 2018; 65:60-67. [DOI: 10.1016/j.neuro.2018.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/06/2018] [Accepted: 02/06/2018] [Indexed: 12/18/2022]
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Cheng YH, Lin YJ, You SH, Yang YF, How CM, Tseng YT, Chen WY, Liao CM. Assessing exposure risks for freshwater tilapia species posed by mercury and methylmercury. ECOTOXICOLOGY (LONDON, ENGLAND) 2016; 25:1181-1193. [PMID: 27207496 DOI: 10.1007/s10646-016-1672-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/11/2016] [Indexed: 06/05/2023]
Abstract
Waterborne and dietborne exposures of freshwater fish to mercury (Hg) in the forms of inorganic (Hg(II)) and organic (methylmercury or MeHg) affect their growth, development, and reproduction. However, an integrated mechanistic risk model framework to predict the impact of Hg(II)/MeHg on freshwater fish is lacking. Here, we integrated biokinetic, physiological and biogeographic data to calibrate and then establish key risk indices-hazardous quotient and exceedance risk-for freshwater tilapia species across geographic ranges of several major rivers in Taiwan. We found that Hg(II) burden was highest in kidney followed by gill, intestine, liver, blood, and muscle. Our results showed that Hg was less likely to pose mortality risk (mortality rate less than 5 %) for freshwater tilapia species. However, Hg is likely to pose the potential hazard to aquatic environments constrained by safety levels for aquatic organisms. Sensitivity analysis showed that amount of Hg accumulated in tilapia was most influenced by sediment uptake rate. Our approach opens up new possibilities for predicting future fish population health with the impacts of continued Hg exposure to provide information on which fish are deemed safe for human consumption.
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Affiliation(s)
- Yi-Hsien Cheng
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China
| | - Yi-Jun Lin
- National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli County, 35053, Taiwan, Republic of China
| | - Shu-Han You
- National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli County, 35053, Taiwan, Republic of China
| | - Ying-Fei Yang
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China
| | - Chun Ming How
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China
| | - Yi-Ting Tseng
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China
| | - Wei-Yu Chen
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan, Republic of China
| | - Chung-Min Liao
- Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan, Republic of China.
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Shimada A, Yamamoto E, Morita T, Yoshida M, Suzuki JS, Satoh M, Tohyama C. Ultrastructural Demonstration of Mercury Granules in the Placenta of Metallothionein-Null Pregnant Mice after Exposure to Mercury Vapor. Toxicol Pathol 2016; 32:519-26. [PMID: 15603537 DOI: 10.1080/01926230490496302] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The placenta plays an important role in the regulation of maternal to fetal transfer of toxic substances, including nonessential metals. Metallothioneins (MTs), which are known to have protective effects against heavy metal toxicity, exist in the placenta, but the exact localization of placental MTs (both MT-I and MT-III) and their physiological role in the placenta exposed to mercury are unclear. The present study was performed to examine the localization of MTs and mercury granules in the placenta of mice exposed to mercury vapor. On gestational day 16, MT-I & II-null and wild-type mice were exposed to mercury vapor at 4.9 to 5.9 mg/m3 for 2 hours. At 24 and 48 hours after exposure, the placentas were examined for mercury distribution (autometallography), MT immunoreactivity, and MT mRNA expression (in situ hybridization). No histological changes were observed in the placentas of either MT-null or wild-type mice. Mercury deposition was demonstrated along the boundary between the junctional zone and the labyrinth zone, as well as in the yolk sac, maternal decidual cells, and labyrinth trophoblasts of both MT-null and wild-type mice. MT-I & -II immunoreactivity, which was confined to wild-type mice, was demonstrated in the yolk sac and decidual cells; mercury was also shown in both structures, suggesting that mercury granules were bound to MTs. MT-III mRNA expression was observed in the yolk sac, decidual cells, and spongiotrophoblasts in both MT-null and wild-type mice. There was, however, no evidence of MT at the boundary between the junctional and labyrinth zones, where substantial mercury deposits were demonstrated. These results suggest that placental MTs and the other unknown molecules may be related to the barrier to the placental transfer of mercury.
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Affiliation(s)
- Akinori Shimada
- Department of Veterinary Pathology, Tottori University, Minami 4-101, Koyama, Tottori-shi, Tottori 680-0945, Japan.
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Hubbs-Tait L, Nation JR, Krebs NF, Bellinger DC. Neurotoxicants, Micronutrients, and Social Environments. Psychol Sci Public Interest 2016; 6:57-121. [DOI: 10.1111/j.1529-1006.2005.00024.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
SUMMARY—Systematic research evaluating the separate and interacting impacts of neurotoxicants, micronutrients, and social environments on children's cognition and behavior has only recently been initiated. Years of extensive human epidemiologic and animal experimental research document the deleterious impact of lead and other metals on the nervous system. However, discrepancies among human studies and between animal and human studies underscore the importance of variations in child nutrition as well as social and behavioral aspects of children's environments that mitigate or exacerbate the effects of neurotoxicants. In this monograph, we review existing research on the impact of neurotoxic metals, nutrients, and social environments and interactions across the three domains. We examine the literature on lead, mercury, manganese, and cadmium in terms of dispersal, epidemiology, experimental animal studies, effects of social environments, and effects of nutrition. Research documenting the negative impact of lead on cognition and behavior influenced reductions by the Center for Disease Control in child lead-screening guidelines from 30 micrograms per deciliter (μg/dL) in 1975 to 25 μg/dL in 1985 and to 10 μg/dL in 1991. A further reduction is currently being considered. Experimental animal research documents lead's alteration of glutamate-neurotransmitter (particularly N-methyl-D-aspartate) activity vital to learning and memory. In addition, lead induces changes in cholinergic and dopaminergic activity. Elevated lead concentrations in the blood are more common among children living in poverty and there is some evidence that socioeconomic status influences associations between lead and child outcomes. Micronutrients that influence the effects of lead include iron and zinc. Research documenting the negative impact of mercury on children (as well as adults) has resulted in a reference dose (RfD) of 0.1 microgram per kilogram of body weight per day (μg/kg/day). In animal studies, mercury interferes with glutamatergic, cholinergic, and dopaminergic activity. Although evidence for interactions of mercury with children's social contexts is minimal, researchers are examining interactions of mercury with several nutrients. Research on the effects of cadmium and manganese on child cognition and behavior is just beginning. Experimental animal research links cadmium to learning deficits, manganese to behaviors characteristic of Parkinson's disease, and both to altered dopaminergic functioning. We close our review with a discussion of policy implications, and we recommend interdisciplinary research that will enable us to bridge gaps within and across domains.
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Affiliation(s)
- Laura Hubbs-Tait
- Department of Human Development and Family Science, Oklahoma State University
| | | | - Nancy F. Krebs
- Department of Pediatrics, University of Colorado School of Medicine
| | - David C. Bellinger
- Department of Neurology, Harvard Medical School; Department of Environmental Health, Harvard School of Public Health; and Children's Hospital Boston
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Marques RC, Abreu L, Bernardi JVE, Dórea JG. Traditional living in the Amazon: Extended breastfeeding, fish consumption, mercury exposure and neurodevelopment. Ann Hum Biol 2016; 43:360-70. [DOI: 10.1080/03014460.2016.1189962] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Bedir Findik R, Celik HT, Ersoy AO, Tasci Y, Moraloglu O, Karakaya J. Mercury concentration in maternal serum, cord blood, and placenta in patients with amalgam dental fillings: effects on fetal biometric measurements. J Matern Fetal Neonatal Med 2016; 29:3665-9. [PMID: 26898132 DOI: 10.3109/14767058.2016.1140737] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
AIM We aimed to determine the extent to which mercury is transmitted from the mother to fetus via the umbilical cord in patients with amalgam dental fillings, and its effect on fetal biometric measurements. METHODS Twenty-eight patients as the study group with amalgam fillings, and 32 of them as the control group were included in this prospective case-control study. The mercury levels were measured in the maternal and cord venous sera, and the placental samples. Two groups were compared in terms of these and the fetal/neonatal biometric measurements. RESULTS In the study group, the maternal and umbilical cord mercury levels were found to be significantly higher than those from the control group (p = 0.006 and p = 0.010, respectively). These high levels did not affect the fetal biometric measurements. CONCLUSIONS The presence of high serum mercury levels in pregnant women with amalgam fillings is important, and warrants further long-term studies in order to investigate the fetal neurological effects as well.
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Affiliation(s)
- Rahime Bedir Findik
- a Department of Obstetrics and Gynecology , Zekai Tahir Burak Women's Health Care Training and Research Hospital , Ankara , Turkey
| | | | - Ali Ozgur Ersoy
- a Department of Obstetrics and Gynecology , Zekai Tahir Burak Women's Health Care Training and Research Hospital , Ankara , Turkey
| | - Yasemin Tasci
- a Department of Obstetrics and Gynecology , Zekai Tahir Burak Women's Health Care Training and Research Hospital , Ankara , Turkey
| | - Ozlem Moraloglu
- a Department of Obstetrics and Gynecology , Zekai Tahir Burak Women's Health Care Training and Research Hospital , Ankara , Turkey
| | - Jale Karakaya
- c Department of Biostatistics , Hacettepe University , Ankara , Turkey
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Dzwilewski KLC, Schantz SL. Prenatal chemical exposures and child language development. JOURNAL OF COMMUNICATION DISORDERS 2015; 57:41-65. [PMID: 26255253 PMCID: PMC4548902 DOI: 10.1016/j.jcomdis.2015.07.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 07/10/2015] [Accepted: 07/16/2015] [Indexed: 05/09/2023]
Abstract
UNLABELLED The goal of this review is to summarize the evidence that prenatal and/or early postnatal exposure to certain chemicals, both manmade (insulating materials, flame retardants, pesticides) and naturally occurring (e.g., lead, mercury), may be associated with delays or impairments in language development. We focus primarily on a subset of more extensively studied chemicals-polychlorinated biphenyls (PCBs), lead, and methyl mercury-for which a reasonable body of literature on neurodevelopmental outcomes is available. We also briefly summarize the smaller body of evidence for other chemicals including polybrominated diphenyl ether flame retardants (PBDEs) and organophosphate pesticides. Very few studies have used specific assessments of language development and function. Therefore, we included discussion of aspects of cognitive development such as overall intellectual functioning and verbal abilities that rely on language, as well as aspects of cognition such as verbal and auditory working memory that are critical underpinnings of language development. A high percentage of prospective birth cohort studies of PCBs, lead, and mercury have reported exposure-related reductions in overall IQ and/or verbal IQ that persist into middle or late childhood. Given these findings, it is important that clinicians and researchers in communication sciences and disorders are aware of the potential for environmental chemicals to impact language development. LEARNING OUTCOMES The goal of this review is to summarize the evidence that prenatal and/or early postnatal exposure to certain chemicals may be associated with delays or impairments in language development. Readers will gain an understanding of the literature suggesting that early exposure to polychlorinated biphenyls (PCBs), lead, and mercury may be associated with decrements in cognitive domains that depend on language or are critical for language development. We also briefly summarize the smaller body of evidence regarding polybrominated diphenyl ether flame retardants (PBDEs) and organophosphate pesticides. Very few studies of exposure to these chemicals have used specific assessments of language development; thus, further investigation is needed before changes in clinical practice can be suggested.
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Affiliation(s)
- Kelsey L C Dzwilewski
- University of Illinois at Urbana-Champaign, Neuroscience Program, 405 North Mathews Avenue, Urbana, IL 61801, USA.
| | - Susan L Schantz
- University of Illinois at Urbana-Champaign, Department of Comparative Biosciences, 2001 South Lincoln Avenue, Urbana, IL 61802, USA.
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Ou L, Chen L, Chen C, Yang T, Wang H, Tong Y, Hu D, Zhang W, Long W, Wang X. Associations of methylmercury and inorganic mercury between human cord blood and maternal blood: a meta-analysis and its application. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2014; 191:25-30. [PMID: 24792881 DOI: 10.1016/j.envpol.2014.04.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 04/08/2014] [Accepted: 04/10/2014] [Indexed: 05/23/2023]
Abstract
Considering the different ability of placental transfer, an assessment of the cord:maternal blood ratio for both methylmercury (MeHg) and inorganic mercury (IHg) is needed especially for interpreting the low-level prenatal exposure. In this study, we conducted a Monte Carlo-based meta-analysis to comprehensively estimate that ratio for MeHg (RMeHg) and IHg (RIHg). The obtained values followed log-normal distributions, with a mean (standard deviation) of 1.89 (0.98) and 1.01 (0.55) for RMeHg and RIHg, respectively. We also estimated the percentage of MeHg in the blood by means of THg in cord and maternal blood using the RMeHg and RIHg, and obtained a value very close to the measured one (relative deviation, -0.4%). In conclusion, the fetus is exposed to approximately twice as much MeHg and to the same level of IHg as in maternal blood; the introduced model provides a rough but reasonable estimate of the percentage of MeHg in the blood.
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Affiliation(s)
- Langbo Ou
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Long Chen
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Cen Chen
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Tianjun Yang
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Huanghuang Wang
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Yindong Tong
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Dan Hu
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Wei Zhang
- School of Environment and Natural Resources, Renmin University of China, Beijing 100872, China.
| | - Wenjing Long
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Xuejun Wang
- Ministry of Education Laboratory of Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
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Influence of prenatal exposure to environmental pollutants on human cord blood levels of glutamate. Neurotoxicology 2013; 40:102-10. [PMID: 24361731 DOI: 10.1016/j.neuro.2013.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 12/09/2013] [Accepted: 12/10/2013] [Indexed: 11/21/2022]
Abstract
Some chemicals released into the environment, including mercury and some organochlorine compounds (OCs), are suspected to have a key role on subclinical brain dysfunction in childhood. Alteration of the glutamatergic system may be one mechanistic pathway. We aimed to determine whether mercury and seven OCs, including PCBs 138, 153, and 180, DDT and DDE, hexachlorobenzene (HCB), and beta-hexachlorocyclohexane (β-HCH) influence the cord levels of two excitatory amino acids, glutamate and aspartate. Second, we evaluated if this association was mediated by glutamate uptake measured in human placental membranes. The study sample included 40 newborns from a Spanish cohort selected according to cord mercury levels. We determined the content of both amino acids in cord blood samples by means of HPLC and assessed their associations with the contaminants using linear regression analyses, and the effect of the contaminants on glutamate uptake by means of [(3)H]-aspartate binding in human placenta samples. PCB138, β-HCH, and the sum of the three PCBs and seven OCs showed a significant negative association with glutamate levels (decrease of 51, 24, 56 and 54%, respectively, in glutamate levels for each 10-fold increase in the contaminant concentration). Mercury did not show a significant correlation neither with glutamate nor aspartate levels in cord blood, however a compensatory effect between T-Hg and both PCB138, and 4,4'-DDE was observed. The organo-metallic derivative methylmercury completely inhibited glutamate uptake in placenta while PCB138 and β-HCH partially inhibited it (IC50 values: 4.9±0.8 μM, 14.2±1.2 nM and 6.9±2.9 nM, respectively). We conclude that some environmental toxicants may alter the glutamate content in the umbilical cord blood, which might underlie alterations in human development.
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Kozikowska I, Binkowski ŁJ, Szczepańska K, Sławska H, Miszczuk K, Śliwińska M, Łaciak T, Stawarz R. Mercury concentrations in human placenta, umbilical cord, cord blood and amniotic fluid and their relations with body parameters of newborns. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2013; 182:256-262. [PMID: 23938449 DOI: 10.1016/j.envpol.2013.07.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 07/03/2013] [Accepted: 07/20/2013] [Indexed: 06/02/2023]
Abstract
Studies were conducted on samples taken from giving birth women (n = 40) living in Poland, representing three age groups: 19-25, 26-30 and 31-38 years old. Mercury concentrations were measured with CV-AAS in placenta, umbilical cord, cord blood and amniotic fluid. The placentas weight did not exceed the 750 g value and was heavier than 310 g. Mean values of Hg concentrations in blood, placenta and umbilical cord were similar (c.a. 9 μg/g). High levels of mercury were noted in cord blood which in 75% of all observations exceeded (up to 17 μg/L) the safe dose set by US EPA (5.8 μg/L). No statistically significant differences in medium level of Hg in all the studied tissues among age groups of women were observed. Positive correlations between Hg concentrations in placenta and umbilical cord and cord blood were revealed as well as some negative ones between mercury concentrations and pregnancy parameters.
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Affiliation(s)
- Iwona Kozikowska
- Institute of Biology, Pedagogical University of Cracow, Podbrzezie 3, 31-054 Cracow, Poland.
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Kim H, Kim KN, Hwang JY, Ha EH, Park H, Ha M, Kim Y, Hong YC, Chang N. Relation between serum folate status and blood mercury concentrations in pregnant women. Nutrition 2013; 29:514-8. [DOI: 10.1016/j.nut.2012.08.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 08/26/2012] [Accepted: 08/26/2012] [Indexed: 11/29/2022]
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Abstract
Mercury (Hg) is a well-known neurotoxicant. Hg exposure at high levels can harm individuals of all ages. Even low level exposure to Hg can damage the brain of fetuses and young children, and affect their central nervous system and cognitive development. The aims of our study were to measure total Hg levels in infant umbilical cord blood and to investigate the risk factors associated with total Hg cord blood levels in various cities in China. Our goal was to provide clues for the prevention of Hg exposure in utero. The results indicated that the average cord blood mercury levels (CBMLs) were (1.81 +/- 1.93) microg/L, which were lower than those found in most previous studies. The concentrations also differed according to geographic region. The CBMLs were not only associated with family economic and living conditions, but also with diet in pregnant women, especially the intake of marine fish, shellfish, poultry, formula milk and fruits.
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Affiliation(s)
- Meiqin Wu
- MOE-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
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Hassauer M, Kaiser E, Schneider K, Schuhmacher‐Wolz U. Collate the literature on toxicity data on mercury in experimental animals and humans (Part I – Data on organic mercury). ACTA ACUST UNITED AC 2012. [DOI: 10.2903/sp.efsa.2012.en-297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Martin Hassauer
- Forschungs‐ und Beratungsinstitut Gefahrstoffe GmbH (FoBiG) Freiburg Germany
| | - Eva Kaiser
- Forschungs‐ und Beratungsinstitut Gefahrstoffe GmbH (FoBiG) Freiburg Germany
| | - Klaus Schneider
- Forschungs‐ und Beratungsinstitut Gefahrstoffe GmbH (FoBiG) Freiburg Germany
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Ohgami N, Iida M, Yajima I, Tamura H, Ohgami K, Kato M. Hearing impairments caused by genetic and environmental factors. Environ Health Prev Med 2012; 18:10-5. [PMID: 22899349 PMCID: PMC3541815 DOI: 10.1007/s12199-012-0300-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 07/26/2012] [Indexed: 01/06/2023] Open
Abstract
Impairments of hearing and balance are major problems in the field of occupational and environmental health. Such impairments have previously been reported to be caused by genetic and environmental factors. However, their mechanisms have not been fully clarified. On the other hand, the inner ear contains spiral ganglion neurons (SGNs) in the organ of Corti, which serve as the primary carriers of auditory information from sensory cells to the auditory cortex in the cerebrum. Inner ears also contain a vestibule in the vicinity of the organ of Corti—one of the organs responsible for balance. Thus, inner ears could be a good target to clarify the pathogeneses of sensorineural hearing losses and impaired balance. In our previous studies with c-Ret knock-in mice and Endothelin receptor B (Ednrb) knock-out mice, it was found that syndromic hearing losses involved postnatal neurodegeneration of SGNs caused by impairments of c-Ret and Ednrb, which play important roles in neuronal development and maintenance of the enteric nervous system. The organ of Corti and the vestibule in inner ears also suffer from degeneration caused by environmental stresses including noise and heavy metals, resulting in impairments of hearing and balance. In this review, we introduce impairments of hearing and balance caused by genetic and environmental factors and focus on impairments of SGNs and the vestibule in inner ears as the pathogeneses caused by these factors.
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Affiliation(s)
- Nobutaka Ohgami
- Unit of Environmental Health Sciences, Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, No. 50 Building 11 floor, 1200 Matsumoto, Kasugai, Aichi, 487-8501, Japan
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Ohgami N, Hori S, Ohgami K, Tamura H, Tsuzuki T, Ohnuma S, Kato M. Exposure to low-dose barium by drinking water causes hearing loss in mice. Neurotoxicology 2012; 33:1276-83. [PMID: 22884792 DOI: 10.1016/j.neuro.2012.07.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 07/26/2012] [Accepted: 07/26/2012] [Indexed: 01/03/2023]
Abstract
PURPOSE We continuously ingest barium as a general element by drinking water and foods in our daily life. Exposure to high-dose barium (>100mg/kg/day) has been shown to cause physiological impairments. Direct administration of barium to inner ears by vascular perfusion has been shown to cause physiological impairments in inner ears. However, the toxic influence of oral exposure to low-dose barium on hearing levels has not been clarified in vivo. We analyzed the toxic influence of oral exposure to low-dose barium on hearing levels and inner ears in mice. EXPERIMENTAL DESIGN We orally administered barium at low doses of 0.14 and 1.4 mg/kg/day to wild-type ICR mice by drinking water. The doses are equivalent to and 10-fold higher than the limit level (0.7 mg/l) of WHO health-based guidelines for drinking water, respectively. After 2-week exposure, hearing levels were measured by auditory brain stem responses and inner ears were morphologically analyzed. After 2-month exposure, tissue distribution of barium was measured by inductively coupled plasma mass spectrometry. RESULTS Low-dose barium in drinking water caused severe hearing loss in mice. Inner ears including inner and outer hair cells, stria vascularis and spiral ganglion neurons showed severe degeneration. The Barium-administered group showed significantly higher levels of barium in inner ears than those in the control group, while barium levels in bone did not show a significant difference between the two groups. Barium levels in other tissues including the cerebrum, cerebellum, heart, liver and kidney were undetectably low in both groups. CONCLUSIONS Our results demonstrate for the first time that low-dose barium administered by drinking water specifically distributes to inner ears resulting in severe ototoxicity with degeneration of inner ears in mice.
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Affiliation(s)
- Nobutaka Ohgami
- Unit of Environmental Health Sciences, Department of Biomedical Sciences, College of Life and Health Sciences, Chubu University, 1200 Matsumoto, Kasugai, Aichi 487-8501, Japan
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Wolkin A, Hunt D, Martin C, Caldwell KL, McGeehin MA. Blood mercury levels among fish consumers residing in areas with high environmental burden. CHEMOSPHERE 2012; 86:967-971. [PMID: 22153999 DOI: 10.1016/j.chemosphere.2011.11.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 11/03/2011] [Accepted: 11/13/2011] [Indexed: 05/31/2023]
Abstract
Mercury is a ubiquitous, persistent toxicant found in the environment. In water, mercury bioaccumulates up the food chain and leads to high concentrations in fish. Consumption of contaminated fish is the major source of exposure to mercury in the US. The objective of this study was to enroll persons living in areas selected by the Environmental Protection Agency (EPA) to have high mercury concentrations and who consume at least 6o z of locally caught fish per week to determine the feasibility of monitoring future trends among a population identified as highly exposed. Blood samples were collected at time of interview and analyzed for mercury. Participants (n=287) were enrolled from North Carolina, Maryland, and South Dakota. Participants reported eating an average of five servings of fish per week. The overall geometric mean for total mercury was 0.75 μg L(-1), with North Carolina having the highest mean level (2.02 μg L(-1)). Overall, 42% of the study population had levels greater than the US geometric mean 0.83 μg L(-1). The number of servings of fish consumed was not found to be associated with blood mercury levels. We were able to identify some persons with elevated mercury concentrations living in areas identified by EPA; however, identifying and monitoring a highly exposed population over time would be challenging.
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Affiliation(s)
- Amy Wolkin
- National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
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22
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Wright B, Pearce H, Allgar V, Miles J, Whitton C, Leon I, Jardine J, McCaffrey N, Smith R, Holbrook I, Lewis J, Goodall D, Alderson-Day B. A comparison of urinary mercury between children with autism spectrum disorders and control children. PLoS One 2012; 7:e29547. [PMID: 22355303 PMCID: PMC3280241 DOI: 10.1371/journal.pone.0029547] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 11/30/2011] [Indexed: 11/22/2022] Open
Abstract
Background Urinary mercury concentrations are used in research exploring mercury exposure. Some theorists have proposed that autism is caused by mercury toxicity. We set out to test whether mercury concentrations in the urine of children with autism were significantly increased or decreased compared to controls or siblings. Methods Blinded cohort analyses were carried out on the urine of 56 children with autism spectrum disorders (ASD) compared to their siblings (n = 42) and a control sample of children without ASD in mainstream (n = 121) and special schools (n = 34). Results There were no statistically significant differences in creatinine levels, in uncorrected urinary mercury levels or in levels of mercury corrected for creatinine, whether or not the analysis is controlled for age, gender and amalgam fillings. Conclusions This study lends no support for the hypothesis of differences in urinary mercury excretion in children with autism compared to other groups. Some of the results, however, do suggest further research in the area may be warranted to replicate this in a larger group and with clear measurement of potential confounding factors.
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Affiliation(s)
- Barry Wright
- North Yorkshire and York Primary Care Trust, York, United Kingdom.
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Bernhoft RA. Mercury toxicity and treatment: a review of the literature. JOURNAL OF ENVIRONMENTAL AND PUBLIC HEALTH 2011; 2012:460508. [PMID: 22235210 PMCID: PMC3253456 DOI: 10.1155/2012/460508] [Citation(s) in RCA: 487] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Accepted: 11/01/2011] [Indexed: 11/30/2022]
Abstract
Mercury is a toxic heavy metal which is widely dispersed in nature. Most human exposure results from fish consumption or dental amalgam. Mercury occurs in several chemical forms, with complex pharmacokinetics. Mercury is capable of inducing a wide range of clinical presentations. Diagnosis of mercury toxicity can be challenging but can be obtained with reasonable reliability. Effective therapies for clinical toxicity have been described.
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Affiliation(s)
- Robin A Bernhoft
- Bernhoft Center for Advanced Medicine, Suite 208, 11677 San Vicente Boulevard, Los Angeles, CA 90049, USA.
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Blanchard KS, Palmer RF, Stein Z. The value of ecologic studies: mercury concentration in ambient air and the risk of autism. REVIEWS ON ENVIRONMENTAL HEALTH 2011; 26:111-8. [PMID: 21905454 DOI: 10.1515/reveh.2011.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Ecologic studies of the spatial relationship between disease and sources of environmental contamination can help to ascertain the degree of risk to populations from contamination and to inform legislation to ameliorate the risk. Population risks associated with persistent low-level mercury exposure have recently begun to be of concern and current reports implicate environmental mercury as a potential contributor in the etiology of various developmental and neurodegenerative diseases including autism and Alzheimer's disease. In this demonstration of preliminary findings, we demonstrate for Bexar County Texas and Santa Clara County California, the hypothesis that the spatial structure of the occurrence of autism has a positive co-variation with the spatial structure of the distribution of mercury in ambient air. The relative risk of autism is greater in the geographic areas of higher levels of ambient mercury. We find that the higher levels of ambient mercury are geographically associated with point sources of mercury emission, such as coal-fired power plants and cement plants with coal-fired kilns. Although this does not indicate a cause, these results should not be dismissed, but rather seen as a preliminary step for generating a hypothesis for further investigation.
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Affiliation(s)
- K Stephen Blanchard
- Department of Sociology, Our Lady of the Lake University, 411 SW 24th Street, San Antonio, TX 78207, USA.
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Abstract
Maternal exposure to methylmercury can adversely affect fetal neurodevelopment. Long-term mercury exposure is best estimated by hair measurement of the metal. The authors analyzed the appropriateness of therapeutic monitoring of hair mercury in women of reproductive age using widely accepted criteria for therapeutic drug monitoring. The analysis reveals that such monitoring can help protect babies from long-term adverse effects, while ensuring appropriate maternal fish consumption.
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Jiang CB, Yeh CY, Lee HC, Chen MJ, Hung FY, Fang SS, Chien LC. Mercury concentration in meconium and risk assessment of fish consumption among pregnant women in Taiwan. THE SCIENCE OF THE TOTAL ENVIRONMENT 2010; 408:518-523. [PMID: 19903566 DOI: 10.1016/j.scitotenv.2009.10.043] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Revised: 10/09/2009] [Accepted: 10/15/2009] [Indexed: 05/28/2023]
Abstract
Meconium is a matrix that can be obtained easily and noninvasively and is useful for detecting antenatal fetal exposure to environmental toxins. Taiwan is an island with high fish consumption, and many pregnant women would like to enjoy the benefits of fish without jeopardizing their health or that of their child. The aim of this study is to assess the mercury concentration in meconium in relation to the health risk of mercury exposure. A total of 198 mother-infant pairs residing in the city of HsinChu were recruited for the study between January 2007 and June 2007. The average mean concentration of mercury in meconium was 79.2+/-7.3 ng g(-1) dry wt We use the Monte Carlo technique to assess the uncertainty in risk assessment and the impact of these uncertainties on the estimation of expected risk of mercury intake from fish in mothers. Based on the FAO/WHO's tolerable daily intake of methylmercury (0.23 microg kg(-1)d(-1)), we found that 17.3% and 14.0% of the daily mercury exposure estimated exceeded the reference dose for foreign-born and Taiwan-born mothers, respectively. We found that the mercury concentration in meconium was much higher than in other studies, except for one study done in Tagum in the Philippines where mercury is used in gold mining. This may be because Asia is the largest emitter of anthropogenic mercury, accounting for 53% of worldwide emissions. Sensitivity analysis suggests that mercury concentration in fish and the rate of ingesting fish may be the key parameters for governments offering risk management guidance to protect the health of mothers and unborn babies.
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Affiliation(s)
- Chuen-Bin Jiang
- Department of Pediatrics, Taipei Mackay Memorial Hospital, Taipei, Taiwan
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27
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Barbieri FL, Gardon J. Hair mercury levels in Amazonian populations: spatial distribution and trends. Int J Health Geogr 2009; 8:71. [PMID: 20025776 PMCID: PMC2816200 DOI: 10.1186/1476-072x-8-71] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 12/21/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mercury is present in the Amazonian aquatic environments from both natural and anthropogenic sources. As a consequence, many riverside populations are exposed to methylmercury, a highly toxic organic form of mercury, because of their intense fish consumption. Many studies have analysed this exposure from different approaches since the early nineties. This review aims to systematize the information in spatial distribution, comparing hair mercury levels by studied population and Amazonian river basin, looking for exposure trends. METHODS The reviewed papers were selected from scientific databases and online libraries. We included studies with a direct measure of hair mercury concentrations in a sample size larger than 10 people, without considering the objectives, approach of the study or mercury speciation. The results are presented in tables and maps by river basin, displaying hair mercury levels and specifying the studied population and health impact, if any. RESULTS The majority of the studies have been carried out in communities from the central Amazonian regions, particularly on the Tapajós River basin. The results seem quite variable; hair mercury means range from 1.1 to 34.2 microg/g. Most studies did not show any significant difference in hair mercury levels by gender or age. Overall, authors emphasized fish consumption frequency as the main risk factor of exposure. The most studied adverse health effect is by far the neurological performance, especially motricity. However, it is not possible to conclude on the relation between hair mercury levels and health impact in the Amazonian situation because of the relatively small number of studies. CONCLUSIONS Hair mercury levels in the Amazonian regions seem to be very heterogenic, depending on several factors. There is no obvious spatial trend and there are many areas that have never been studied. Taking into account the low mercury levels currently handled as acceptable, the majority of the Amazonian populations can be considered exposed to methylmercury contamination. The situation for many of these traditional communities is very complex because of their high dependence on fish nutrients. It remains difficult to conclude on the Public Health implication of mercury exposure in this context.
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Defining a Lowest Observable Adverse Effect Hair Concentrations of Mercury for Neurodevelopmental Effects of Prenatal Methylmercury Exposure Through Maternal Fish Consumption: A Systematic Review. Ther Drug Monit 2009; 31:670-82. [DOI: 10.1097/ftd.0b013e3181bb0ea1] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Barbieri FL, Cournil A, Gardon J. Mercury exposure in a high fish eating Bolivian Amazonian population with intense small-scale gold-mining activities. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2009; 19:267-277. [PMID: 20183195 DOI: 10.1080/09603120802559342] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Methylmercury exposure in Amazonian communities through fish consumption has been widely documented in Brazil. There is still a lack of data in other Amazonian countries, which is why we conducted this study in the Bolivian Amazon basin. Simple random sampling was used from a small village located in the lower Beni River, where there is intense gold mining and high fish consumption. All participants were interviewed and hair samples were taken to measure total mercury concentrations. The hair mercury geometric mean in the general population was 3.02 microg/g (CI: 2.69-3.37; range: 0.42-15.65). Age and gender were not directly associated with mercury levels. Fish consumption showed a positive relation and so did occupation, especially small-scale gold mining. Hair mercury levels were lower than those found in Brazilian studies, but still higher than in non-exposed populations. It is necessary to assess mercury exposure in the Amazonian regions where data is still lacking, using a standardized indicator.
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Richardson GM, Brecher RW, Scobie H, Hamblen J, Samuelian J, Smith C. Mercury vapour (Hg0): Continuing toxicological uncertainties, and establishing a Canadian reference exposure level. Regul Toxicol Pharmacol 2009; 53:32-8. [DOI: 10.1016/j.yrtph.2008.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Revised: 10/07/2008] [Accepted: 10/16/2008] [Indexed: 12/01/2022]
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Lederman SA, Jones RL, Caldwell KL, Rauh V, Sheets SE, Tang D, Viswanathan S, Becker M, Stein JL, Wang RY, Perera FP. Relation between cord blood mercury levels and early child development in a World Trade Center cohort. ENVIRONMENTAL HEALTH PERSPECTIVES 2008; 116:1085-91. [PMID: 18709170 PMCID: PMC2516590 DOI: 10.1289/ehp.10831] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Accepted: 03/31/2008] [Indexed: 05/02/2023]
Abstract
OBJECTIVE This study was designed to determine whether prenatal mercury exposure, including potential releases from the World Trade Center (WTC) disaster, adversely affects fetal growth and child development. METHODS We determined maternal and umbilical cord blood total mercury of nonsmoking women who delivered at term in lower Manhattan after 11 September 2001, and measured birth outcomes and child development. RESULTS Levels of total mercury in cord and maternal blood were not significantly higher for women who resided or worked within 1 or 2 miles of the WTC in the month after 11 September, compared with women who lived and worked farther away. Average cord mercury levels were more than twice maternal levels, and both were elevated in women who reported eating fish/seafood during pregnancy. Regression analyses showed no significant association between (ln) cord or maternal blood total mercury and birth outcomes. Log cord mercury was inversely associated with the Bayley Scales of Infant Development psychomotor score [Psychomotor Development Index (PDI)] at 36 months (b = -4.2, p = 0.007) and with Performance (b = -3.4, p = 0.023), Verbal (b = -2.9, p = 0.023), and Full IQ scores (b = -3.8, p = 0.002) on the Wechsler Preschool and Primary Scale of Intelligence, Revised (WPPSI-R), at 48 months, after controlling for fish/seafood consumption and other confounders. Fish/seafood consumption during pregnancy was significantly associated with a 5.6- to 9.9-point increase in 36-month PDI, and 48-month Verbal and Full IQ scores. CONCLUSIONS Blood mercury was not significantly raised in women living or working close to the WTC site in the weeks after 11 September 2001. Higher cord blood mercury was associated with reductions in developmental scores at 36 and 48 months, after adjusting for the positive effects of fish/seafood consumption during pregnancy.
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Affiliation(s)
- Sally Ann Lederman
- Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, New York, New York 10032, USA.
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Palmer RF, Blanchard S, Wood R. Proximity to point sources of environmental mercury release as a predictor of autism prevalence. Health Place 2008; 15:18-24. [PMID: 18353703 DOI: 10.1016/j.healthplace.2008.02.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Revised: 01/16/2008] [Accepted: 02/04/2008] [Indexed: 11/27/2022]
Abstract
The objective of this study was to determine if proximity to sources of mercury pollution in 1998 were related to autism prevalence in 2002. Autism count data from the Texas Educational Agency and environmental mercury release data from the Environmental Protection Agency were used. We found that for every 1000 pounds of industrial release, there was a corresponding 2.6% increase in autism rates (p<.05) and a 3.7% increase associated with power plant emissions(P<.05). Distances to these sources were independent predictors after adjustment for relevant covariates. For every 10 miles from industrial or power plant sources, there was an associated decreased autism Incident Risk of 2.0% and 1.4%, respectively (p<.05). While design limitations preclude interpretation of individual risk, further investigations of environmental risks to child development issues are warranted.
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Affiliation(s)
- Raymond F Palmer
- University of Texas Health Science Center, San Antonio Department of Family and Community Medicine, 7703 Floyd Curl Drive, San Antonio Texas, Mail Code 7794, TX 78229-3900, USA.
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Abstract
This review covers the toxicology of mercury and its compounds. Special attention is paid to those forms of mercury of current public health concern. Human exposure to the vapor of metallic mercury dates back to antiquity but continues today in occupational settings and from dental amalgam. Health risks from methylmercury in edible tissues of fish have been the subject of several large epidemiological investigations and continue to be the subject of intense debate. Ethylmercury in the form of a preservative, thimerosal, added to certain vaccines, is the most recent form of mercury that has become a public health concern. The review leads to general discussion of evolutionary aspects of mercury, protective and toxic mechanisms, and ends on a note that mercury is still an "element of mystery."
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Affiliation(s)
- Thomas W Clarkson
- Department of Environmental Medicine, University of Rochester School of Medicine, New York, USA.
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Palmer RF, Blanchard S, Stein Z, Mandell D, Miller C. Environmental mercury release, special education rates, and autism disorder: an ecological study of Texas. Health Place 2006; 12:203-9. [PMID: 16338635 DOI: 10.1016/j.healthplace.2004.11.005] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/01/2004] [Indexed: 11/28/2022]
Abstract
The association between environmentally released mercury, special education and autism rates in Texas was investigated using data from the Texas Education Department and the United States Environmental Protection Agency. A Poisson regression analysis adjusted for school district population size, economic and demographic factors was used. There was a significant increase in the rates of special education students and autism rates associated with increases in environmentally released mercury. On average, for each 1,000 lb of environmentally released mercury, there was a 43% increase in the rate of special education services and a 61% increase in the rate of autism. The association between environmentally released mercury and special education rates were fully mediated by increased autism rates. This ecological study suggests the need for further research regarding the association between environmentally released mercury and developmental disorders such as autism. These results have implications for policy planning and cost analysis.
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Affiliation(s)
- Raymond F Palmer
- University of Texas Health Science Center, San Antonio Department of Family and Community Medicine, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900, USA.
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Mahaffey KR. Fish and shellfish as dietary sources of methylmercury and the omega-3 fatty acids, eicosahexaenoic acid and docosahexaenoic acid: risks and benefits. ENVIRONMENTAL RESEARCH 2004; 95:414-428. [PMID: 15220075 DOI: 10.1016/j.envres.2004.02.006] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Revised: 02/02/2004] [Accepted: 02/05/2004] [Indexed: 05/24/2023]
Abstract
Fish and shellfish supply the human diet with not only complex nutrients including the omega-3 fatty acids, but also highly toxic chemicals including methylmercury. The dietary essential fatty acids are linoleic and alpha-linolenic acid. Two omega-3 fatty acids with longer carbon chains, eicosahexaenoic acid (EPA) and docosahexaenoic acid (DHA), can be synthesized in humans from alpha-linolenic precursors. Though not required in the diet per se, EPA and DHA have important roles in metabolism. The almost exclusive source of preformed dietary DHA is fish and shellfish. These foods are also an important source of EPA. In marked contrast to the benefits of fish and shellfish as sources of preformed omega-3 fatty acids, fish and shellfish are almost exclusively the dietary source of methylmercury. Fortunately, these chemicals are not uniformly distributed across many species of fish and shellfish. The purpose of this article is to provide information on the comparative distribution of these chemicals and nutrients to help groups formulating dietary recommendations.
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Affiliation(s)
- Kathryn R Mahaffey
- Division of Exposure Assessment, Coordination and Policy, Office of Science Coordination and Policy, US Environmental Protection Agency, Washington, DC 20464,
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