Mercury Exposure In Children Research Articles

Neuropsychological Effects of Mercury Exposure in Children and Adolescents of the Amazon Region, Brazil

BackgroundStudies with children exposed to methylmercury (MeHg) through fish consumption in the Brazilian Amazon region report that the high levels of hair Hg are associated with significant decreases in intelligence, memory, attention, and visuospatial processing. ObjectiveTo investigate the relationship between mercury exposure and neuropsychological functions in riverside communities of the Brazilian Amazon. Method263 participants aged 6 to 14 years old were assessed, from resettlement regions, near the Madeira river, Rondônia, Brazil. To assess the neuropsychological functions we used the following instruments: intelligence (WASI), working memory (Corsi Block-Tapping Task and Digit Span), verbal fluency (Word Generation - NEPSY II), inhibitory control (Inhibition Errors - NEPSY II), shifting (Trail Making Test) and manual motor dexterity (Grooved PegBoard Test). Socioeconomic status was obtained through household surveys. Total Hg levels were quantified hair samples (Total HgH) collected from the occipital region of the scalp and analyzed by Cold Vapor Atomic Absorption Spectrometry. ResultsThe group in the upper quartile of Total HgH levels presented lower scores on the tasks that assessed estimated IQ, visuospatial working memory, semantic knowledge and phonological verbal fluency, when compared to the group in the lower quartile level. A regression analysis controlled for age, sex, and maternal education showed that for each increase of 10 μg/g of Total HgH, there was a decrease around half standard deviation in Verbal IQ, estimated IQ scores, semantic knowledge, phonological verbal fluency and for verbal and visuospatial working memory. ConclusionsHigh concentrations of Total Hg in hair were associated with a lower performance in neuropsychological functions tests. The results show that environmental exposure to Hg is associated to children and adolescents’ lower neuropsychological performance in the riverine and resettled areas of the Brazilian Amazon region.

Mercury Exposure in Children of the Wanshan Mercury Mining Area, Guizhou, China.

To evaluate the mercury (Hg) exposure level of children located in a Hg mining area, total Hg concentrations and speciation were determined in hair and urine samples of children in the Wanshan Hg mining area, Guizhou Province, China. Rice samples consumed by these same children were also collected for total mercury (THg) and methyl-mercury (MeHg) analysis. The geometric mean concentrations of THg and MeHg in the hair samples were 1.4 (range 0.50–6.0) μg/g and 1.1 (range 0.35–4.2) μg/g, respectively, while the geometric mean concentration of urine Hg (UHg) was 1.4 (range 0.09–26) μg/g Creatinine (Cr). The average of the probable daily intake (PDI) of MeHg via rice consumption was 0.052 (0.0033–0.39) µg/kg/day, which significantly correlated with the hair MeHg concentrations (r = 0.55, p < 0.01), indicating that ingestion of rice is the main pathway of MeHg exposure for children in this area. Furthermore, 18% (26/141) of the PDIs of MeHg exceeded the USEPA Reference Dose (RfD) of 0.10 µg/kg/day, indicating that children in this area are at a high MeHg exposure level. This paper for the first time evaluates the co-exposure levels of IHg and MeHg of children living in Wanshan mining area, and revealed the difference in exposure patterns between children and adults in this area.

Health Assessment Of Mercury Exposure In Children Of Riparian And Urban Communities During The Flooding Stage Of An Hydroelectrical Power Plant At The Madeira River

Health Assessment Of Mercury Exposure In Children Of Riparian And Urban Communities During The Flooding Stage Of An Hydroelectrical Power Plant At The Madeira River

Assessment of renal functions with different glomerular filtration rate formulas in children with acute exposure of mercury

Abstract Objective: Our aim was to determine whether cystatin C level has a superiority to creatinine to assess kidney functions in rapid decreases of glomerular filtration rate due to acute mercury exposure in children. Eight different glomerular filtration rate calculation formulas which have been used creatinine and/or cystatin C were also compared. Methods: Serum urea, creatinine and cystatin C values of 39 mercury exposed children were measured. Glomerular filtration rates were calculated by eight different formulas. Patient group was divided into three subgroups according to mercury levels. Results: Cystatin C and mercury levels of the patients were found significantly different from control group (p&lt;0.001). There was not a significant difference in creatinine and urea values between two groups (p=0.913, p=0.236). There was not a significant difference between patient and control groups in GFR calculations which have been used serum creatinine and height or which have been used urea additional to them (p=0.069, p=0.559, p=0.424, p=0.945, respectively), but there was a significant difference between patient and control groups in GFR calculations which have been used cystatin C only or creatinine, urea and height in addition to this (p&lt;0.001, p&lt;0.001, p=0.042, p&lt;0.001, respectively). In sugroup analysis, cystatin C results and the results of three GFR calculations of four GFR calculations which were used cystatin C were found different in control group according to subgroups but there was not a difference between subgroups. Conclusion: Cystatin C level is a better indicator than creatinine to assess kidney functions in rapid decreases of glomerular filtration rate due to acute exposure of mercury. Formulas using cystatin C gave better results than formulas using creatinine and height in estimation of glomerular filtration rate.

PS-001 Fish Consumption Pattern And Its Association With Hair Mercury Levels In Hong Kong Preschool Children

Background Low-dose mercury exposure has been shown to be associated with adverse childhood health outcomes. Fish is the major source of mercury exposure in children. Our aim was to investigate the associations between estimated fish intake with total mercury (tHg), inorganic mercury (iHg), and methylmercury (MeHg). Methods Based on fish food frequency questionnaire (FFQ) data, subjects above the top and below the bottom quartiles of monthly fish intake frequency were contacted for recruitment. Subject hair tHg, iHg, MeHg levels were determined, and fish intake assessed by fish FFQ and 14-day food diary (FD). Associations between fish intake and hair mercury were analysed. Results 96 children were recruited and 38 of them completed the FD. Among these 96 children and those who have FD data, 55% and 50% were high fish consumers, respectively. The mean ratio of iHg: MeHg was 1:1.4. Comparisons between hair mercury levels and fish intake levels of high and low fish consumers are shown in Figure 1. Fish intakes calculated from both FFQs and FD were positively correlated with tHg, iHg and MeHg (all p Conclusions Fish intake data obtained from both FFQs and FDs were positively associated with hair mercury levels. FDs performed better than FFQs. The high proportion of iHg: MeHg is unexpected and warrants further study.

Urinary Mercury Level, Neurobehavioral Performance, and Some Biochemical Markers in Children with Amalgam Restorations

At present, there is a lack of scientific evidence on toxicity from low-level mercury exposure in children. Despite the debate over the safety of dental amalgam fillings, amalgam is still widely used to restore posterior teeth in pediatric dentistry. Although, children could be at greater risk to harm from low-level exposure due to their developing nervous systems. Hence, this research was carried out to define some potential health effects from dental amalgam on children's health. Children were selected from those attending the Pedodontic clinic, Faculty of Dentistry, Tanta University. They were subjected to clinical examination, neurobehavioral and intelligence quotient (IQ) assessment, urinary mercury level, serum; malondialdehyde (MDA), reduced glutathione (GSH), zinc (Zn), and gamma amino butyric acid (GABA) measurement. The present study revealed thatthe mean urinary mercury level was significantly higher in the amalgam group (8.15+0.99μg/L) than in the control group (3.53+0.94 μg/L). The urinary mercury level in children who had more than two amalgams or had duration 2 years or more was higher than children who had less than 2 amalgams or had duration less than 2 years. There was no difference in IQ between children with and without amalgam fillings. The children who had amalgam restoration were estimated to be more withdrawn, more anxious/depressed, and to have more social problems than the control group. Furthermore, greater attention problems and delinquent/rule-breaking problems were recorded in the children with amalgam filling than in the control children. Also there was significant increase of serum MDA level and significant decrease of serum levels of GSH, Zn, and GABA levels in amalgam group than the control. These changes were more evident in children who had more than 2 amalgams or had duration 2 years or more.

Serum Paraoxonase-1 (PON-1) Genotype and Exposure to Organophosphorous Insectides—Is There a High-Risk Population?

The Health Studies Branch (HSB) is responsible for responding to domestic and international requests for assistance with suspected and known environmental-associated public health threats as well as pursuing original environmental research. The HSB employs personnel with a wide variety of educational backgrounds and professional training including epidemiology, medicine, toxicology, statistics, and other environmental public health-related disciplines. This wide range of expertise is necessary to address the broad scope of potential environmental health threats. HSB scientists conduct studies on environmental exposures. Recent examples include the following: mercury exposure in children living in large urban areas, exposure to brevetoxins and microcystins arising from harmful algal blooms, and occupational exposures to pesticides. This article will present a brief description of an ongoing study of insecticide exposure and paraoxonase-1 (PON-1) genotype in banana plantation workers in Chinandega, Nicaragua. We will then discuss the enzyme PON-1 and its potential role in organophosphate insecticide metabolism and toxicity.

Efficacy of Succimer Chelation of Mercury at Background Exposures in Toddlers: A Randomized Trial

To examine whether succimer, a mercaptan compound known to reduce blood lead concentration in children, reduces blood mercury concentration. We used samples from a randomized clinical trial of succimer chelation for lead-exposed children. We measured mercury levels in pre-treatment samples from 767 children. We also measured mercury levels in blood samples drawn 1 week after treatment began (n = 768) and in a 20% random sample of the children who received the maximum 3 courses of treatment (n = 67). A bootstrap-based isotonic regression method was used to compare the trend with time in the difference between the adjusted mean mercury concentrations in the succimer group and that in the placebo group. The adjusted mean organic mercury concentration in the succimer group relative to the placebo group fell from 99% at baseline to 82% after 3 courses of treatment (P for trend = .048), but this resulted from the prevention of the age-related increase in the succimer group. Succimer chelation for low level organic mercury exposure in children has limited efficacy.

Hair mercury levels, fish consumption, and cognitive development in preschool children from Granada, Spain ,

The main source of human exposure to mercury is the consumption of fish contaminated with methylmercury, which may adversely affect early neurodevelopment. This study assessed mercury levels in hair of preschoolers in Spain, where fish consumption is elevated, with the aim of investigating the influence of their fish intake and other factors on mercury exposure, and evaluating their association with cognitive development. A population-based birth cohort from Granada (Spain) was studied at the age of 4yr. Total mercury (T-Hg) levels were determined in children's hair, and daily fish intake was assessed by a food frequency questionnaire. The McCarthy Scales of Children's Abilities (MSCA) were used to assess children's motor and cognitive abilities. Complete data were gathered on 72 children, and multivariate analyses were performed to evaluate the influence of mercury exposure and fish intake on MSCA outcomes. Mean concentration of T-Hg in hair was 0.96 microg/g (95% confidence interval=0.76; 1.20 microg/g). T-Hg levels were associated with higher frequency of oily fish consumption, place of residence, maternal age, and passive smoking. After adjustment for fish intake, T-Hg levels > or =1microg/g were associated with decrements in the general cognitive (-6.6 points), memory (-8.4 points), and verbal (-7.5 points) MSCA scores. Higher mercury exposure in children from this Mediterranean area was associated with cognitive development delay. Studies on the putative benefits of fish intake during early development should consider mercury exposure from different fish species.

Health implications of mercury exposure in children

Mercury is a ubiquitous environmental toxin that can produce a wide range of health effects in humans. It is found in three chemical forms: organic, inorganic and elemental (mercury). The sources of exposure are also markedly different for the different forms of mercury. Diet, especially fish and other seafood, is the main source of exposure of the general public to organic mercury. Dental amalgam is the most important source for elemental mercury vapour in the general population. Inorganic mercury compounds are known as 'mercuric salts', which are sometimes used in skin-lightening creams and as antiseptic creams and ointments. Though its use has been banned in some countries, these products are still available on the world market. Each mercury form possesses a different risk to human health. Mercury can be transferred prenatally to the developing foetus via the placenta or postnatally from breast milk to the nursing infant. Children are potentially more susceptible to mercury than adults due to differences in the stages of brain development and organ growth that occur during the foetal, infant and childhood developmental periods. The objective of this paper is to review the relevant literature concerning transplacental and lactational exposure to mercury, taking into account mercury speciation, in order to have a critical assessment of its adverse health effects. Attention is also given to available studies in Saudi Arabia where skin-lightening creams, dental amalgam and thimerosal are still in use.

Measuring mercury exposure in children

Measuring mercury exposure in children

Immune Function Effects of Dental Amalgam in Children: A Randomized Clinical Trial

Dental amalgam is a widely used restorative material containing 50 percent elemental mercury that emits mercury vapor. No randomized clinical trials have determined whether there are adverse immunological effects associated with this low-level mercury exposure in children. The objective of this study was to evaluate a subpopulation of the participants in the New England Children's Amalgam Trial for in vitro manifestations of immunotoxic effects of dental amalgam. The authors conducted a randomized clinical trial in which children requiring dental restorative treatment were randomly assigned to receive either amalgam for posterior restorations or resin-based composite restorations. They assessed 66 children, aged 6 to 10 years, for total white blood cell counts, specific lymphocyte (T-cell and B-cell) counts and lymphocyte, neutrophil and monocyte responsiveness across a five-year period. Because of the small number of participants, the authors acknowledge that the study is exploratory in nature and has limited statistical power. The mean number of tooth surfaces restored during the five-year period was 7.8 for the amalgam group and 10.1 for the composite group. In the amalgam group, there was a slight, but not statistically significant, decline in responsiveness of T cells and monocytes at five to seven days after treatment; the authors consistently observed no differences at six, 12 or 60 months. The findings of this study confirm that treatment of children with amalgam restorations leads to increased, albeit low-level, exposure to mercury. In this exploratory analysis of immune function, amalgam exposure did not cause overt immune deficits, although small transient effects were observed five to seven days after restoration placement. These findings suggest that immunotoxic effects of amalgam restorations are minimal and transient in children and most likely do not need to be of concern to practitioners considering the use of this restorative dental material.

Neurological outcomes in children with and without amalgam-related mercury exposure: Seven years of longitudinal observations in a randomized trial

Although large-scale, randomized trials involving children have been completed and their results demonstrate an absence of neurobehavioral effects from clinical exposure to mercury amalgam, neurological findings from such studies have not been reported. The authors conducted a randomized, prospective trial examining the safety of dental amalgam in which 507 children aged 8 through 12 years were assigned to treatment with either amalgam or resin-based composite. During seven years of follow-up, the authors performed annual clinical neurological examinations, including an evaluation of neurological hard signs (NHSs), presence of tremor and neurological soft signs (NSSs). The authors found no significant differences between treatment groups in any of the neurological measures. Groups did not differ with respect to the presence or absence of NHSs or tremor, nor the presence or absence or severity of NSSs at any point. As expected, NSS severity scores diminished with increasing age. Even at the levels of amalgam exposure in this study (a mean of 7.7-10.7 amalgam surfaces per subject across the seven years of follow-up), the authors conclude that exposure to mercury from dental amalgam does not adversely affect neurological status. The current evidence is that potential neurobehavioral or neurological effects from dental amalgam mercury exposure in children are inconsequential.

Low‐level chronic mercury exposure in children and adolescents: Meta‐analysis

Mercury is a well-known neurotoxin. There are three kinds of mercury exposure: elemental mercury poisoning, inorganic mercury poisoning and organomercury poisoning. Organomercury is the most toxic. Twenty-four hour urine for mercury and blood mercury are the gold standards for diagnosis of mercury poisoning, including low-level chronic mercury exposure. Other tests for mercury level are discussed. The purpose of the present paper was to review recent data on the nature, pathophysiology, pharmacokinetics, diagnostic methods, treatment and the linkage to neurodevelopmental disabilities of mercury exposure in children. A literature search was undertaken of MEDLINE (1980-2003), and American Academy of Pediatrics, American Medical Association, American Dental Association, World Health Organization and Center for Disease Control websites. The search string 'mercury' was used in MEDLINE and articles were selected as appropriate by two independent reviewers. All relevant information was reviewed and data were extracted by two independent reviewers. Based on the meta-analysis of the accuracy of hair mercury, hair mercury levels correlated with mercury level in blood (sample size weighted correlation coefficient, r w = 0.61), with 24 h urine ( r w = 0.46) and with cord blood ( r w = 0.64). However, the correlation for hair mercury level with 24 h urine level and blood level was not high enough to replace them in clinical decision-making of individual patient. Epidemiological evidence has shown that low-level mercury poisoning is not a cause of autism (relative risk = 0.49, 95%CI = 0.36-0.66). The risk of neurodevelopmental disabilities from low-level exposure to methylmercury from the regular consumption of fish is still controversial even after combining results from different epidemiological studies worldwide. There is a lack of data in the literature about the effect of chelation therapy in children with neurodevelopmental disabilities. Mercury poisoning should be diagnosed only with validated methods. There is no evidence to support the association between mercury poisoning and autism.

Environmental mercury exposure in children: South China's experience

Environmental mercury levels significantly increased in the past decades following its increase in industrial applications. In spite of an increasing concern on the potential harmful effects of mercury on children, there is no reported data for the Chinese population. The relationship between dietary habit and environmental mercury exposure in Chinese children was studied. The hair and blood mercury levels of Chinese children aged above 3 years in 2000 March to September, were studied. Sociodemographic data, dietary habits of the past 6 months, and other risk factors for environmental mercury exposure were collected. Those children with blood mercury levels above the toxic range (i.e. > 45 nmol/L) and their family members were further evaluated and their blood and hair mercury levels were monitored before and after Fishing-Moratorium period (June to August 2000) in South China Sea. Altogether, 137 Chinese children (mean age, 7.2 years) were recruited. The mean hair mercury level was 2.2 p.p.m and the mean blood mercury level was 17.6 nmol/L. There was a strong correlation (r = 0.88) between hair and blood mercury levels in our cohort. Frequency of fish consumption correlated with hair (r = 0.51) and blood (r = 0.54) mercury levels. For those children who consumed fish more than 3 times/week, hair and blood mercury levels were twice as high as those who consumed fish l-3 times/week and threefold of those who never consumed fish. Five children and 12 family members had toxic blood mercury levels. Their blood (P < 0.0001) and hair (P = 0.02) mercury levels dropped significantly after reducing fish consumption during Fishing-Moratorium period. Both blood and hair (i.e. Tissue) mercury levels of children in Hong Kong was elevated and correlated with the frequency of fish consumption.

AN ASSESSMENT OF MERCURY EXPOSURE AMONG YOUNG CHILDREN LIVING IN NYC

ISEE-555 Introduction: Mercury exposure in young children may occur from a variety of sources containing mercury in different forms (elemental mercury, inorganic mercury salts, and organic mercury compounds). This presentation describes the methods and preliminary results of a study designed to examine dietary (organic mercury), medicinal (inorganic or elemental mercury), or traditional (elemental mercury) exposure among children living in New York City (NYC) by collecting questionnaire data and measuring mercury in biological samples. The study is focusing on communities where mercury exposure from various sources is suspected. Methods: A cross-sectional study design is utilized. Blood and/or urine samples are collected from children (<10 years of age) seen in community-based health clinics in neighborhoods where mercury may currently or historically have been used in residential settings. Standardized questionnaires are administered to parents of participating children. Individual blood and urine mercury concentrations are directly reported to the parent(s) or guardian(s) of the child, and to the child’s health care provider. Excess urine samples, routinely provided for other diagnostic purposes, are collected anonymously at the clinic to assess the potential for participation bias to influence the study results. A door-to-door pilot study to assess mercury exposure in children living in neighborhoods with Botanicas (stores selling items used for religious purposes, e.g., mercury) is also conducted. Urine samples (only) and questionnaire data are collected in the door-to-door study. Study blood and urine mercury levels are compared to levels found in previous studies and national assessments (background). Results: We compare the background levels of mercury to the mercury levels of children in all three study populations. Using the sampling results, we also assess whether mercury concentrations for the children can be predicted by parent-reported mercury exposures; are consistent with values reported for other pediatric populations; and are associated with demographic or environmental factors. Comparison of the anonymous residual urine sample results to those obtained with parental consent and interview allows an assessment of selection bias, potentially introduced through the consent process. Discussion: The data obtained by this study will be used to determine if mercury exposure above background is occurring in the study population. If so, then guidance on ways to reduce future exposure will be provided to parents and guardians. Community outreach and programs for monitoring childhood exposure to mercury will be developed depending upon study findings.

Mercury exposure in children with autistic spectrum disorder: case-control study.

Although mercury has been proven to be a neurotoxicant, there is a lack of data to evaluate the causal relationship between mercury and autism. We aim to see if there is increased mercury exposure in children with autistic spectrum disorder. We performed a cross-sectional cohort study over a 5-month period in 2000 to compare the hair and blood mercury levels of children with autistic spectrum disorder (n = 82; mean age 7.2 years) and a control group of normal children (n = 55; mean age 7.8 years). There was no difference in the mean mercury levels. The mean blood mercury levels of the autistic and control groups were 19.53 and 17.68 nmol/L, respectively (P = .15), and the mean hair mercury levels of the autistic and control groups were 2.26 and 2.07 ppm, respectively (P = .79). Thus, the results from our cohort study with similar environmental mercury exposure indicate that there is no causal relationship between mercury as an environmental neurotoxin and autism.

Elemental Mercury Exposure

To the Editor.— In the article by Hudson et al1 concerning mercury exposure of children of thermometor plant workers, they stated that "this is the first report demonstrating mercury exposure in children of mercury workers." On Sept 28, 1954, a case report of primary mercury poisoning in an infant was presented at a meeting of the North Pacific Pediatric Society, Victoria, British Columbia, Canada. Unfortunately, the case was never submitted for publication. The patient, a 20-month-old male infant, was referred because of fever, irritability, tremor, and refusal to walk.

Elemental Mercury Exposure Among Children of Thermometer Plant Workers

Because evidence of mercury exposure was found among workers of a mercury thermometer-manufacturing plant in March 1984, the Vermont Department of Health studied the workers' children for both exposure to mercury and evidence of mercury toxicity. The median urine mercury level of 23 workers' children was 25 micrograms/L. This was significantly higher than the level (5 micrograms/L) among 39 children randomly selected from nonworkers' households in the same community (P less than .001). Mercury-in-air levels measured in workers' homes were higher than those measured in control homes. A significant correlation was found between the urine mercury levels of the workers' children and the urine mercury levels of their working parents. No child had frank mercury toxicity. No evidence of neurologic toxicity among exposed children was discovered by a pediatric neurologist who examined these and unexposed children without knowledge of their exposure status. This is the first report demonstrating mercury exposure in children of mercury workers. Although toxic effects of mercury were not demonstrated at these levels of exposure, children of mercury workers are at risk for mercury exposure and potential mercury toxicity.