Elemental mercury vapour toxicity, treatment, and prognosis after acute, intensive exposure in chloralkali plant workers. Part I: History, neuropsychological findings and chelator effects

Investigation and monitoring of heavy metal poisoning

Historically, heavy metal measurement and interpretation has been a highly specialised area performed only in a handful of centres within the UK. However, recent years have seen a move to more local testing due to the repatriation of referred work into pathology networks and the increased availability of inductively coupled plasma mass spectrometry technology. While management of significant poisoning is still overseen by tertiary care poisoning specialists, management of milder cases may be undertaken locally.Non-specialist clinical scientists and clinicians need to know when heavy metal testing is appropriate, which samples are required (and any specific requirements around collection) and how to interpret and act on the results.This Best Practice article provides guidance on the investigation and monitoring of the toxic elements most frequently encountered in general medical practice; lead, mercury and arsenic. It is intended as a reference guide for the non-specialist and as a comprehensive summary for clinical toxicologists and clinical scientists.

Relating mercury occurrence in soil gases at establishments hosting children to historical mercury-using activities in Paris, France

Volatile pollutants from former industrial sites can degrade the buildings' indoor air quality that were built after the industrial activities. Since 2010, environmental assessments have been conducted in French establishments hosting sensitive populations identified as being on or near potentially contaminated former industrial sites. These projects are based on historical studies traditionally carried out as part of managing contaminated sites, to determine which substances should be analyzed. They pinpoint former activities likely to have stored or used pollutants. We show that the historical information collected is not effective in targeting sites with increased probability of mercury being present in soil gases. Environmental history has demonstrated the existence of large-scale artisanal contamination, both prior to and concomitant with the industrial era. Classic historical studies would not take into account artisanal activities, which are less documented than industrial activities. We carried out additional research for three schools located in three different Parisian districts. Although information on activities which could have emitted mercury was relatively imprecise (in terms of location, type and duration of activities) and uncertainties exist about the completeness of the archival documents available, our investigations identified several mercury-using activities that had not been identified during the classic historical study. However, we have shown that the number of activities identified does not provide information on how mercury has affected soil gas. Consequently, although a more extensive historical research improves knowledge about the presence of potential mercury-using activities, our study shows that a systematic analysis of mercury as part of the assessment of establishments hosting sensitive populations remains relevant. This approach should be applied to other cities around the world.

Prenatal methylmercury exposure is associated with decrease heart rate variability in children

BACKGROUND

Although several epidemiological studies have suggested mercury (Hg) might be associated with cardiotoxicity, the impact of Hg exposure on cardiac autonomic activity and blood pressure in children has not been investigated at Hg exposure levels equivalent to the Environmental Protection Agency (EPA) reference dose.

OBJECTIVE

To investigate the association between low dose prenatal and recent methylmercury (MeHg) exposures and cardiac autonomic function and blood pressure with adjustment for factors such as fish consumption among children from a high fish consumption coastal city.

METHODS

Children aged 7-8 years were recruited from the birth cohort of our previous study. Heart rate variability (HRV), resting heart rate (RHR) and blood pressure were measured as surrogate markers of cardiac autonomic function. Cord blood and current whole blood Hg concentration were used as biomarkers of prenatal and recent MeHg exposure, respectively. Recent fish consumption information was estimated with a food frequency questionnaire.

RESULTS

Among 604 children, median cord blood and whole blood Hg concentrations were 45.9 nmol/L (IQR: 32.8-65.03 nmol/L) and 13.57 nmol/L (IQR: 9.29-19.72 nmol/L), respectively. Our results demonstrated that prenatal MeHg exposure was associated with decreased HRV (i.e. low CVRR, SDRR, and RMSSD), reflecting reduced parasympathetic activity (i.e. low CCV_HF and HF), and a sympathovagal balance shift toward sympathetic predominance (i.e. high %LF and LF/HF ratio). Adjustment of recent fish consumption further increased the significance and magnitude of the adverse associations of MeHg.

CONCLUSION

The results of this study suggest that prenatal MeHg exposure is associated with decreased parasympathetic modulation of cardiac autonomic function in children.

Sequence-defined oligomer as a modular platform for selective sub-picomolar detection and removal of Hg2+

A modular synthetic platform for selective sensing and removal of Hg2+ was developed.

Toxin-Induced Parkinsonism

Toxins identified as causing parkinsonism and being related to overall idiopathic Parkinson disease risk range from heavy metals to pesticides to contaminants in synthetic heroin. Several described in this article exhibit significant oxidative stress on neurons of the central nervous system and have a particular predilection toward damage of dopaminergic neurons. Although many of these toxins have well-established connections with Parkinson disease risk, a few continue to be studied with data still being produced. The parkinsonisms caused by these agents have variable responses to dopaminergic therapies. This article discusses manganese, mercury, MPTP, organochlorines, organophosphates, paraquat, rotenone, and Agent Orange.

Self-Powered Gallium-Based Liquid-Metal Beating Heart

Mercury beating heart is a well-known phenomenon that consists of a mercury droplet covered with aqueous acid and an iron nail. However, mercury is highly poisonous, and its vapor is especially dangerous. Thus, related studies and applications on mercury have often been hindered. Here, we proposed another beating heart but employed a different material, i.e., GaIn alloy with low toxicity. A stainless steel wire was utilized to touch the side of the liquid-metal droplet in basic solution. Based on this method, periodic oscillation could be kept continuous and steady. This finding suggests a more feasible and safer way to realize beating behaviors, which would shed light on a variety of future applications, such as pump and mixer for the mini device.

Unusual complication of an Alaskan cruise: thinking outside the box

A 69-year-old man with a medical history of hypertension and diabetes presented with altered mental status once he returned from a 14-day Alaskan cruise. An extensive workup for stroke was negative. His physical examination was normal without any focal motor deficits, but he had developed memory loss and paresthesia. He admitted to eating a lot of fish when he was in Alaska. The whole-blood mercury level was found to be elevated. He was managed conservatively and his symptoms resolved completely in a few days. This led to a diagnosis of organic mercury toxicity.

Effective removal of mercury from aqueous streams via electrochemical alloy formation on platinum

Retrieval of mercury from aqueous streams has significant environmental and societal importance due to its very high toxicity and mobility. We present here a method to retrieve mercury from aqueous feeds via electrochemical alloy formation on thin platinum films. This application is a green and effective alternative to traditional chemical decontamination techniques. Under applied potential, mercury ions in solution form a stable PtHg₄ alloy with platinum on the cathode. A 100 nanometres platinum film was fully converted to a 750 nanometres thick layer of PtHg₄. The overall removal capacity is very high, > 88 g mercury per cm³. The electrodes can easily be regenerated after use. Efficient and selective decontamination is possible in a wide pH range, allowing processing of industrial, municipal, and natural waters. The method is suited for both high and low concentrations of mercury and can reduce mercury levels far below the limits allowed in drinking water.

Natural Phytotherapeutic Antioxidants in the Treatment of Mercury Intoxication-A Review

Heavy metals taken into the organism can make the toxic effects on the metabolism in various ways. For example, they may interact with proteins to alter and inhibit their enzymatic and structural functions. Mercury is one of the toxic elements that are widely distributed in nature. Mercury toxicity poses a serious threat to human health. It is an element that causes oxidative stress to increase in individuals, leading to tissue damage. Oxidative stress is the result of the imbalance between the production of oxidative species and cellular antioxidant defense. Phytotherapy continues to play an important role in health care. Natural phytotherapeutic antioxidants, exhibit a broad sequence of biological impacts, including anti-oxidative stress, anti-aging, anti-toxicicity and anticancer. Many studies have also shown that the phytotherapeutic agents play an important role in the removal of mercury from the tissue and in reducing oxidative stress. Our goal in this review was to investigate alternative ways of extracting the mercury in the tissue.

Elemental mercury neurotoxicity and clinical recovery of function: A review of findings, and implications for occupational health

This paper assessed approximately 30 studies, mostly involving occupationally exposed subjects, concerning the extent to which those who developed elemental mercury (Hg)-induced central and/or peripheral neurotoxicities from chronic or acute exposures recover functionality and/or performance. While some recovery occurred in the vast majority of cases, the extent of such recoveries varied considerably by individual and endpoint. Factors accounting for the extensive inter-individual variation in toxicity and recovery were not specifically assessed such as age, gender, diet, environmental enrichment, chelation strategies and dose-rate. While the data indicate that psychomotor endpoints often show substantial and relatively rapid (i.e., 2-6 months) recovery and that neuropsychological endpoints display slower and less complete recovery, generalizations are difficult due to highly variable study designs, use of different endpoints measured between studies, different Hg exposures based on blood/urine concentrations and Hg dose-rates, the poor capacity for replicating findings due to the unpredictable/episodic nature of harmful exposures to elemental Hg, and the inconsistency of the initiation of studies after induced toxicities and the differing periods of follow up during recovery periods. Finally, there is strikingly limited animal model literature on the topic of recovery/reversibility of elemental Hg toxicity, a factor which significantly contributes to the overall marked uncertainties for predicting the rate and magnitude of recovery and the factors that affect it.

A Challenging Case of Acute Mercury Toxicity

Background

Mercury exists in multiple forms: elemental, organic, and inorganic. Its toxic manifestations depend on the type and magnitude of exposure. The role of colonoscopic decompression in acute mercury toxicity is still unclear. We present a case of acute elemental mercury toxicity secondary to mercury ingestion, which markedly improved with colonoscopic decompression.

Clinical Case

A 54-year-old male presented to the ED five days after ingesting five ounces (148 cubic centimeters) of elemental mercury. Examination was only significant for a distended abdomen. Labs showed elevated serum and urine mercury levels. An abdominal radiograph showed radiopaque material throughout the colon. Succimer and laxatives were initiated. The patient had recurrent bowel movements, and serial radiographs showed interval decrease of mercury in the descending colon with interval increase in the cecum and ascending colon. Colonoscopic decompression was done successfully. The colon was evacuated, and a repeat radiograph showed decreased hyperdense material in the colon. Three months later, a repeat radiograph showed no hyperdense material in the colon.

Conclusion

Ingested elemental mercury can be retained in the colon. Although there are no established guidelines for colonoscopic decompression, our patient showed significant improvement. We believe further studies on this subject are needed to guide management practices.

Persistence of mercury-induced motor and sensory neurotoxicity: systematic review of workers previously exposed to mercury vapor

Elemental mercury (Hg0) is a well-recognized neurotoxicant, but it is uncertain whether and for how long its neurotoxicity persists. Among studies that evaluated previously-exposed workers, only one examined workers during and also years after exposure had ceased. The objective of this review is to create a series of 'synthetic' longitudinal studies to address the question of persistence of Hg0 neurotoxicity in occupationally exposed workers. We systematically reviewed studies describing objective motor and sensory effects in previously-exposed mercury workers. Data from physical examination (PE), neurobehavioral (NB) tests, and electrophysiological studies (EPS) were extracted into structured tables and examined for their consistency and dose-relatedness and then compared with the corresponding results from studies of currently exposed workers. We identified six cohorts that described neurological findings in 1299 workers, examined an average of 4.8-30 years after the cessation of exposure. Historical group mean UHg levels ranged from 23 to >500 μg/L, with UHg levels >6000 μg/L in some individuals. Overall, few findings were significant; most were inconsistent across the previous-exposure studies, and in comparisons between studies of previously and currently exposed workers. The results of this systematic review indicate that Hg0-related neurotoxic effects detectable on PE, NB testing, and EPS are substantially reversed over time. To the extent that such effects do persist, they are reported principally in workers who have had very high-dose exposures. In addition, based on the limited available data, those effects reported to persist have been described as having little or no functional significance.

A simple and selective colorimetric mercury (II) sensing system based on chitosan stabilized gold nanoparticles and 2,6-pyridinedicarboxylic acid

The development of simple and cost-effective methods for the detection and treatment of Hg²⁺ in the environment is an important area of research due to the serious health risk that Hg²⁺ poses to humans. Colorimetric sensing based on the induced aggregation of nanoparticles is of great interest since it offers a low cost, simple, and relatively rapid procedure, making it perfect for on-site analysis. Herein we report the development of a simple colorimetric sensor for the selective detection and estimation of mercury ions in water, based on chitosan stabilized gold nanoparticles (AuNPs) and 2,6-pyridinedicarboxylic acid (PDA). In the presence of Hg²⁺, PDA induces the aggregation of AuNPs, causing the solution to change colors varying from red to blue, depending on the concentration of Hg²⁺. The formation of aggregated AuNPs in the presence of Hg²⁺ was confirmed using transmission electron microscopy (TEM) and UV-Vis spectroscopy. The method exhibits linearity in the range of 300nM to 5μM and shows excellent selectivity towards Hg²⁺ among seventeen different metal ions and was successfully applied for the detection of Hg²⁺ in spiked river water samples. The developed technique is simple and superior to the existing techniques in that it allows detection of Hg²⁺ using the naked eye and simple and rapid colorimetric analysis, which eliminates the need for sophisticated instruments and sample preparation methods.

Evaluation of the toxic potential of calcium carbide in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg(9)

In the present study the toxic potential of calcium carbide (CaC2) was studied on the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg(9). The third instar larvae were exposed to 2, 4, 8, 16 and 32×10(-3)g/ml of CaC2 in diet for 24h. The results reveal that the dose 2×10(-3)g/ml was not toxic but the remaining doses showed a dose dependent significant increase in the hsp70 expression, β-galactosidase activity, tissue damage, oxidative stress markers (lipid peroxidation and protein carbonyl content), glutathione-S-transferase activity, expression of Caspase 3 and 9, apoptotic index and DNA damage (midgut cells). A significant reduction as compared to control group in total protein, glutathione content and acetylcholinesterase activity was also observed. The Inductively Coupled Plasma Atomic Emission Spectroscopy analysis (ICPAES) reveals the presence of copper, iron, sodium, aluminium, manganese, calcium, nickel and mercury. The toxic effects of CaC2 in the present study may be attributed to the impurities present in it.

Mercury Exposure Assessment and Spatial Distribution in A Ghanaian Small-Scale Gold Mining Community

Mercury is utilized worldwide in artisanal and small-scale gold mining (ASGM) and may pose a risk for miners and mining communities. While a number of studies have characterized mercury in ASGM communities, most have focused on a single media and few have taken a holistic approach. Here, a multiple media exposure assessment and cross-sectional study of mercury was conducted in 2010 through 2012 in northeast Ghana with a small-scale gold mining community, Kejetia, a subsistence farming community, Gorogo, and an urban ASGM gold refinery in Bolgatanga. The objective was to assess mercury in a range of human (urine and hair) and ecological (household soil, sediment, fish, and ore) samples to increase understanding of mercury exposure pathways. All participants were interviewed on demographics, occupational and medical histories, and household characteristics. Participants included 90 women of childbearing age and 97 adults from Kejetia and 75 adults from Gorogo. Median total specific gravity-adjusted urinary, hair, and household soil mercury were significantly higher in Kejetia miners (5.18 µg/L, 0.967 µg/g, and 3.77 µg/g, respectively) than Kejetia non-miners (1.18 µg/L, 0.419 µg/g, and 2.00 µg/g, respectively) and Gorogo participants (0.154 µg/L, 0.181 µg/g, and 0.039 µg/g) in 2011. Sediment, fish, and ore Hg concentrations were below guideline values. Median soil mercury from the Bolgatanga refinery was very high (54.6 µg/g). Estimated mean mercury ingestion for Kejetia adults from soil and dust exceeded the U.S. Environmental Protection Agency reference dose (0.3 µg Hg/kg·day) for pica (0.409 µg Hg/kg·day) and geophagy (20.5 µg Hg/kg·day) scenarios. Most participants with elevated urinary and household soil mercury were miners, but some non-miners approached and exceeded guideline values, suggesting a health risk for non-mining residents living within these communities.

An Investigation of Organic and Inorganic Mercury Exposure and Blood Pressure in a Small-Scale Gold Mining Community in Ghana

There is increasing concern about the cardiovascular effects of mercury (Hg) exposure, and that organic methylmercury and inorganic Hg²⁺ may affect the cardiovascular system and blood pressure differentially. In small-scale gold mining communities where inorganic, elemental Hg exposures are high, little is known about the effects of Hg on blood pressure. In 2011, we assessed the relationship between Hg exposure and blood pressure (BP) in a cross-sectional study of adults from a small-scale gold mining community, Kejetia, and subsistence farming community, Gorogo, in Ghana’s Upper East Region. Participants’ resting heart rate and BP were measured, and hair and urine samples were provided to serve as biomarkers of organic and inorganic Hg exposure, respectively. Participants included 70 miners and 26 non-miners from Kejetia and 75 non-miners from Gorogo. Total specific gravity-adjusted urinary and hair Hg was higher among Kejetia miners than Kejetia non-miners and Gorogo participants (median urinary Hg: 5.17, 1.18, and 0.154 µg/L, respectively; hair Hg: 0.945, 0.419, and 0.181 µg/g, respectively). Hypertension was prevalent in 17.7% of Kejetia and 21.3% of Gorogo participants. Urinary and hair Hg were not significantly associated with systolic or diastolic BP for Kejetia or Gorogo participants while adjusting for sex, age, and smoking status. Although our results follow trends seen in other studies, the associations were not of statistical significance. Given the unique study population and high exposures to inorganic Hg, the work contained here will help increase our understanding of the cardiovascular effects of Hg.

Sources of Mercury Exposure to Children in Low- and Middle-Income Countries

BACKGROUND

Many children in low- and middle-income countries face enhanced risks of exposure to contaminants via the environment, parental occupation, and other routes. While mercury (Hg) is a global pollutant whose transport properties allow it to have an impact even in pristine areas, the presence of significant Hg sources in the developing world can cause localized effects that are more severe than those observed in other areas.

OBJECTIVES

This paper provides a narrative review of sources of Hg exposure to people in the developing world with a particular focus on children, and presents an overview of key aspects to this important issue.

METHODS

We searched Web of Knowledge and Google Scholar using keywords including combinations of "mercury" and one or more of the following: "children," "exposure," "breast milk," "artisanal mining," "prenatal," "religion," "medicine," "dental amalgam," "chlor-alkali," "VCM," "vaccine," "e-waste," "industry," "beauty," "cosmetics," "strategies," "child labor," "costs," and "developing countries" to find peer-reviewed articles pertaining to Hg exposure in the developing world.

RESULTS

Sources of Hg exposure include mining, consumption, industrial operations, religious practices, traditional medicines, beauty products, vaccines, dental amalgams, and waste scavenging and recycling.

CONCLUSION

Children in the developing world are often subject to higher levels of Hg exposure than those living in developed countries due to the higher prevalence of Hg-intensive industrial processes and consumer products, lack of environmental regulation, and limits in mobility and food choices, among other factors. This issue can be addressed through additional research to fill in data gaps on exposure sources, establish sound and enforceable policies, and increase education and participation in affected communities. Challenges to addressing this problem include limited resources for needed equipment, training, and manpower to implement solutions.

Chelation therapy in intoxications with mercury, lead and copper

In the present review we provide an update of the appropriate use of chelating agents in the treatment of intoxications with compounds of mercury, lead and copper. The relatively new chelators meso-2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercapto-propanesulphonate (DMPS) can effectively mobilize deposits of mercury as well as of lead into the urine. These drugs can be administered orally and have relatively low toxicity compared to the classical antidote dimercaptopropanol (BAL). d-Penicillamine has been widely used in copper overload, although 2,3-dimercaptosuccinic acid or tetrathiomolybdate may be more suitable alternatives today. In copper-toxicity, a free radical scavenger might be recommended as adjuvant to the chelator therapy.

Acute mercury poisoning presenting as fever of unknown origin in an adult woman: a case report

Introduction

Mercury intoxication may present in a wide range of clinical forms from a simple disease to fatal poisoning. This article presents a case of acute mercury poisoning, a rare condition that presents challenges for diagnosis with fever of unknown origin.

Case presentation

A 52-year-old Caucasian woman was admitted to the hospital with high fever, sore throat, a rash over her entire body, itching, nausea, and extensive muscle pain. She had cervical, bilateral axillary and mediastinal lymphadenopathies. We learned that her son and husband had similar symptoms. After excluding infectious pathologies, autoimmune diseases and malignancy were investigated. Multiple organs of our patient were involved and her fever persisted at the fourth week of admission. A repeat medical history elicited that her son had brought mercury home from school and put it on the hot stove, and the family had been exposed to the fumes for a long period of time. Our patient’s serum and urine mercury levels were high. She was diagnosed with mercury poisoning and treated accordingly.

Conclusions

Mercury vapor is a colourless and odorless substance. Therefore, patients with various unexplained symptoms and clinical conditions should be questioned about possible exposure to mercury.

Relationship of estimated dietary intake of n-3 polyunsaturated fatty acids from fish with peripheral nerve function after adjusting for mercury exposure

BACKGROUND

Some clinical studies have suggested that ingestion of n-3 polyunsaturated fatty acids (PUFA) has neuroprotective effects on peripheral nerve function. However, few epidemiological studies have examined the effect of dietary n-3 PUFA intake from fish consumption on peripheral nerve function, and none have controlled for co-occurrence of methylmercury exposure from fish consumption.

OBJECTIVES

We evaluated the effect of estimated dietary n-3 PUFA intake on peripheral nerve function after adjusting for biomarkers of methylmercury and elemental mercury in a convenience sample of 515 dental professionals.

METHODS

We measured sensory nerve conduction (peak latency and amplitude) of the median, ulnar and sural nerves and total mercury concentrations in hair and urine samples. We estimated daily intake (mg/day) of the total n-3 PUFA, n-3 docosahexaenoic acid (DHA), and n-3 eicosapentaenoic acid (EPA) based on a self-administrated fish consumption frequency questionnaire. We also collected information on mercury exposure, demographics and other covariates.

RESULTS

The estimated median intakes of total n-3 PUFA, n-3 EPA, and n-3 DHA were 447, 105, and 179 mg/day, respectively. The mean mercury concentrations in urine (1.05 μg/L) and hair (0.49 μg/g) were not significantly different from the US general population. We found no consistent association between n-3 PUFA intake and sensory nerve conduction after adjusting for mercury concentrations in hair and urine although some positive associations were observed with the sural nerve.

CONCLUSIONS

In a convenience sample of dental professionals, we found little evidence suggesting that dietary intake of n-3 PUFAs from fish has any impact on peripheral nerve function after adjustment for methylmercury exposure from fish and elemental mercury exposure from dental amalgam.

Metals, oxidative stress and neurodegeneration: a focus on iron, manganese and mercury

Essential metals are crucial for the maintenance of cell homeostasis. Among the 23 elements that have known physiological functions in humans, 12 are metals, including iron (Fe) and manganese (Mn). Nevertheless, excessive exposure to these metals may lead to pathological conditions, including neurodegeneration. Similarly, exposure to metals that do not have known biological functions, such as mercury (Hg), also present great health concerns. This review focuses on the neurodegenerative mechanisms and effects of Fe, Mn and Hg. Oxidative stress (OS), particularly in mitochondria, is a common feature of Fe, Mn and Hg toxicity. However, the primary molecular targets triggering OS are distinct. Free cationic iron is a potent pro-oxidant and can initiate a set of reactions that form extremely reactive products, such as OH. Mn can oxidize dopamine (DA), generating reactive species and also affect mitochondrial function, leading to accumulation of metabolites and culminating with OS. Cationic Hg forms have strong affinity for nucleophiles, such as -SH and -SeH. Therefore, they target critical thiol- and selenol-molecules with antioxidant properties. Finally, we address the main sources of exposure to these metals, their transport mechanisms into the brain, and therapeutic modalities to mitigate their neurotoxic effects.

Mercury as a cause of fulminant hepatic failure in a child: case report and literature review

Fulminant hepatic failure (FHF) in children is devastating unless urgent liver transplantation is undergone. Intoxication or drug-related FHF is a well-known group of causes leading to FHF. Mercury intoxication is described in the literature to cause hepatitis but not described to cause DRESS (drug reaction with eosinophilia and systemic symptoms) syndrome and FHF in the same patient. We describe a child with mercury intoxication and FHF with clinical features fulfilling DRESS syndrome criteria. To our best knowledge, this is the first case report of fatal acute liver failure secondary to mercury intoxication in the English literature. Mercury intoxication should receive a worldwide attention to its consequences in order to minimize the morbidities and mortalities that arise from its intoxication.

Household poisoning cases from mercury brought from school

Mercury has a number of unique and fascinating properties. It is present in the environment in several forms, both organic and inorganic. Each of these forms has somewhat unique properties that differentiate them from the other forms, but all are toxic to humans in one way or the others. Mercury has been proven to be a potential source of poisoning in children as a result of the inappropriate handling of a liquid mercury. The cases of metallic mercury vapor intoxication not associated with occupational exposure may occur in school science laboratories, from mercury dust and powders, from latex paint containing a mercury-based fungicide, and from normal wear or installation of dental amalgam fillings. Another source of toxic mercury exposure can be broken thermometers, barometers, or sphygmomanometers that may occur in the home, and children are often victims of environmental exposure. In this paper, we present three members of a family who were exposed to mercury brought home from school by a family member. Since the mercury exposure was not known, the initial presentation and clinical picture suggested a misdiagnosis, a contagious infectious disease, because the onset of symptoms occurred at different times in the same family members. A subsequent change to a diagnosis of mercury intoxication and chelation therapy with meso-2,3-dimercaptosuccinic acid was started.

Neither DMPS nor DMSA is Effective in Quantitative Elimination of Elemental Mercury After Intentional IV Injection

BACKGROUND

Intravenous injection of elemental mercury (Hg) is rare and considered relatively harmless. Treatment recommendations vary and the effectiveness of chelation therapy is controversial.

CASE REPORT

A 27-year-old man intravenously injected 1.5 mL of elemental Hg. Within 12 hours he became febrile, tachycardic and dyspneic. Physical examination was unremarkable. X-rays showed scattered radiodense deposits in the lung, heart, intestinal wall, liver and kidney. The serum Hg level on admission was 172 microg/L and peaked on day 6 at 274 microg/L. Cumulative renal elimination during a five day oral treatment period with 2,3-dimercaptopropane-1-sulfonate (DMPS) and meso-2,3-dimercaptosuccinic acid (DMSA) was 8 mg and 3 mg, respectively.

CONCLUSION

Although urinary excretion could be enhanced during chelation therapy, Hg deposits in organs resulted in negligible elimination of mercury compared to the exposed dose.

Cognitive dysfunction associated with elemental mercury ingestion and inhalation: a case study

A 63-year-old man with a history of alcohol dependence ingested elemental mercury as a suicide gesture. Serial abdominal X-rays showed gradual but incomplete clearance of mercury from the colon. Routine chest X-ray showed evidence of punctate radiopaque materials in the lower lobe of the right lung. Blood and urine mercury levels both exceeded thresholds considered to be associated with cognitive dysfunction. Elicited cognitive deficits were most prominent in processing speed, flexibility, and response inhibition. Semantic fluency, visuospatial processing, and recall memory for visual and low-context verbal material were also affected. The deficits may have been attributable primarily to alcohol abuse. Elemental mercury is not readily absorbed from the gastrointestinal tract; however, mercury vapor, which was inhaled inadvertently, readily crosses the blood-brain barrier and is neurotoxic. We argue, therefore, that mercury toxicity is more likely than not to have been a factor contributing to the patient's cognitive dysfunction.

Mercury exposures and symptoms in smelting workers of artisanal mercury mines in Wuchuan, Guizhou, China

Mercury exposures to smelting workers of artisanal mercury mines in Wuchuan, Guizhou, China were evaluated by urine and hair mercury survey. The mean urinary mercury (U-Hg), hair total mercury (T-Hg), and hair methyl mercury (Me-Hg) for smelting workers was 1060 microg/g creatinine (microg/g Cr), 69.3 and 2.32 microg/g, respectively. The results were significantly higher than that of control group, which is 1.30 microg/g Cr, 0.78 and 0.65 microg/g, correspondingly. The average urinary beta2-microglobulin (beta2-MG) was 248 microg/g Cr for the exposed group contrasting to 73.5 microg/g Cr for the control group and the data showed a serious adverse effect on renal system for the smelting workers. The workers were exposed to mercury vapor through inhalation, and the exposure route of Me-Hg may be through intake of polluted diet. The results indicate that age, alcohol drinking, and smoking are not crucial factors controlling the urine and hair mercury levels for the exposed and the control group. Clinical symptoms including finger and eyelid tremor, gingivitis, and typical dark-line on gums were observed in six workers. This study indicated that the smelting workers in Wuchuan were seriously exposed to mercury vapor.

Effect of Lycopene on Nephrotoxicity Induced by Mercuric Chloride in Rats

Oxidative stress is an important molecular mechanism for kidney injury in mercury poisoning. We studied lycopene, a potent carotenoid found in tomatoes due to its large antioxidant properties, and also evaluated the ability of lycopene to prevent HgCl(2) nephrotoxicity. Rats were injected with HgCl(2) (0 or 5 mg/kg body weight, subcutaneously) 6 hr after lycopene administration (0, 10, 25 or 50 mg/kg by gavage) and were killed 12 hr after HgCl(2) exposure. HgCl(2)-induced inhibition of delta-aminolevulinate dehydratase activity (approximately 35%) and increase of lipid peroxidation in kidney (approximately 37%) were prevented by lycopene. However, lycopene did not prevent the increase of plasma creatinine levels (approximately 123%) and renal tubular necrosis induced by HgCl(2). Glutathione peroxidase and catalase activities were enhanced (approximately 71% and approximately 41%), while superoxide dismutase activity was depressed (approximately 44%) in HgCl(2)-treated rats when compared to control and these effects were prevented by lycopene. Our results indicate that although lycopene did not prevent HgCl(2)-induced renal failure, it could play a beneficial role against HgCl(2) toxicity by preventing lipid peroxidation and changes in the activity of delta-aminolevulinate dehydratase and antioxidant enzymes.

The toxicology of mercury and its chemical compounds

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."

24-Hour Provoked Urine Excretion Test for Heavy Metals in Children with Autism and Typically Developing Controls, a Pilot Study

INTRODUCTION

The complementary and alternative medicine practice of prescribing chelators to children with autism is based on the premise that the chronic symptoms of autism can be ameliorated by reducing heavy metal body burden. However, there has not been definitive evidence, published to date, to support the assertion that children with autism are at increased risk of an excess chelatable body burden of heavy metals. The oral chelator meso-2,3-dimercaptosuccinic acid (DMSA) can be used diagnostically to mobilize heavy metals from extravascular pools, enhancing the identification of individuals who have a chelatable body burden.

METHODS

Seventeen children with autism and five typically developing children were enrolled in a pilot study to test for chelatable body burden of Arsenic (As), Cadmium (Cd), Lead (Pb), and Mercury (Hg). Evaluation included a questionnaire regarding potential exposure to heavy metals, diet restrictions, a baseline 24-hour urine collection, and a DMSA-provoked urine collection. Urine collections were sent for As, Cd, Pb, and Hg quantification by Inductively Coupled Plasma-Mass Spectrometry. Unprovoked reference ranges were used in the interpretation of all collections.

RESULTS

Fifteen autistic children and four typically developing children completed the study. Three autistic subjects excreted one metal in greater quantity during the provoked excretion than baseline. Two of these were very close to the limit of detection. In the third case, the provoked excretion of mercury was between the upper limit of normal and lower limit of the potentially toxic reference range. Fish was removed from this child's diet for greater than one month, and the provoked excretion test repeated. The repeat excretion of mercury was within the normal range.

CONCLUSION

In the absence a proven novel mode of heavy metal toxicity, the proportion of autistic participants in this study whose DMSA provoked excretion results demonstrate an excess chelatable body burden of As, Cd, Pb, or Hg is zero. The confidence interval for this proportion is 0-22%.

Lactational exposure to inorganic mercury: evidence of neurotoxic effects

This study examined the effects of inorganic mercury (mercuric chloride - HgCl2) exposure exclusively through maternal milk on biochemical parameters related to oxidative stress (glutathione and thiobarbituric acid reactive substances levels, glutathione peroxidase and glutathione reductase activities) in the cerebellum of weanling mice. These parameters were also evaluated in the cerebellum of mothers, which were subjected to intraperitoneal injections of HgCl2 (0, 0.5 and 1.5 mg/kg, once a day) during the lactational period. Considering the relationship between cerebellar function and motor activity, the presence of motor impairment was also evaluated in the offspring exposed to HgCl2 during lactation. After treatments (at weaning), pups lactationally exposed to inorganic mercury showed high levels of mercury in the cerebellar tissue, as well as significant impairment in motor performance in the rotarod task and decreased locomotor activity in the open field. Offspring and dams did not show changes in cerebellar glutathione levels or glutathione peroxidase activity. In pups, lactational exposure to inorganic mercury significantly increased cerebellar lipoperoxidation, as well as the activity of cerebellar glutathione reductase. However, these phenomena were not observed in dams. These results indicate that inorganic mercury exposure through maternal milk is capable of inducing biochemical changes in the cerebellum of weanling mice, as well as motor deficit and these phenomena appear to be related to the pro-oxidative properties of inorganic mercury.

Mercury exposure: evaluation and intervention the inappropriate use of chelating agents in the diagnosis and treatment of putative mercury poisoning

Public awareness of the potential for mercury to cause health problems has increased dramatically in the last 15 years. It is now widely recognized that significant exposure to all forms of mercury (elemental/metallic and both inorganic and organic compounds) can result in a variety of adverse health effects, including neurological, renal, respiratory, immune, dermatologic, reproductive, and developmental sequellae. And while the various media have made the general population cognizant of the need to avoid unnecessary exposure to this naturally occurring element, there has also evolved a growing tendency to attribute unexplainable neurologic, as well as other, signs and symptoms to mercury, whether or not significant exposure to mercury has actually occurred. For the physician, making a diagnosis of mercury intoxication can be difficult, because many of the clinical signs and symptoms of mercury exposure can also be attributed to any number of causes, including undiagnosed neurological diseases, pharmacotherapy, vitamin or mineral deficiencies, and psychological stress. The physician must be able to recognize the clinical manifestations of mercury intoxication, and understand the importance of biological markers in making a definitive diagnosis of mercury poisoning. In a desire to treat the patient complaining of symptoms similar to some that can be caused by mercury, a growing number of physicians, particularly those in alternative medicine fields, result to chelation to "rid" the body of the mercury, believed to be the cause of the ailments. And although the use of chelation is increasing, controlled studies showing that this procedure actually improves outcome are lacking. If chelation therapy is considered to be indicated, the attending physician should communicate the risks of chelation to the patient before beginning treatment with metal-chelating drugs.

Molecular and ionic mimicry and the transport of toxic metals

Despite many scientific advances, human exposure to, and intoxication by, toxic metal species continues to occur. Surprisingly, little is understood about the mechanisms by which certain metals and metal-containing species gain entry into target cells. Since there do not appear to be transporters designed specifically for the entry of most toxic metal species into mammalian cells, it has been postulated that some of these metals gain entry into target cells, through the mechanisms of ionic and/or molecular mimicry, at the site of transporters of essential elements and/or molecules. The primary purpose of this review is to discuss the transport of selective toxic metals in target organs and provide evidence supporting a role of ionic and/or molecular mimicry. In the context of this review, molecular mimicry refers to the ability of a metal ion to bond to an endogenous organic molecule to form an organic metal species that acts as a functional or structural mimic of essential molecules at the sites of transporters of those molecules. Ionic mimicry refers to the ability of a cationic form of a toxic metal to mimic an essential element or cationic species of an element at the site of a transporter of that element. Molecular and ionic mimics can also be sub-classified as structural or functional mimics. This review will present the established and putative roles of molecular and ionic mimicry in the transport of mercury, cadmium, lead, arsenic, selenium, and selected oxyanions in target organs and tissues.

A new cutaneous sign of mercury poisoning?

Chronic mercury poisoning is becoming a health concern because of extensive pollution of water and fish, and the increasing consumption of fish in the human diet. Mercury is extremely toxic to the body, especially the central nervous system, but diagnosis is difficult because of the lack of specific signs. A total of 11 patients were observed to have a nonpruritic or mildly pruritic discreet papular and papulovesicular eruption that correlated with high blood mercury levels. The mercury evidently came from increased seafood consumption. All of the patients improved when they were placed on either a seafood-free diet or chelation therapy. Physicians should suspect mercury poisoning in patients who eat a high-seafood diet who present with an asymptomatic or mildly pruritic papular or papulovesicular eruption.

Elemental mercury poisoning in occupational and residential settings

In its elemental form, mercury is the only metal that is in a liquid state at room temperature. It readily volatilizes at standard temperature and pressure, and its presence in open containers can result in biologically significant air concentrations in unventilated or poorly ventilated spaces. In recent years, elemental mercury has proven to be a potential source of toxicosis through either unintentional exposure or exposure resulting from inappropriate handling of liquid mercury acquired from school science laboratories or abandoned industrial facilities or warehouses. The shiny, silvery appearance of mercury in its liquid form makes it particularly enticing to children, and its insolubility in water and tendency to form beads when disturbed add to its mystique. This paper presents two case studies in which excessive exposure to elemental mercury vapor has resulted in adverse health effects in the exposed individuals: one in the workplace and one in a residential setting. These case studies serve to emphasize that primary care physicians, public health officials, and science educators need to recognize the potential risk posed by inhalation exposure to mercury vapors, and health practitioners need to be able to recognize the health signs and symptoms of such exposure. Public health professionals and those in charge of public and private education facilities should also be keenly aware of the necessity of prompt mitigation of human exposure should a spill or other mercury exposure scenario occur.

Vitamin C, glutathione, or lipoic acid did not decrease brain or kidney mercury in rats exposed to mercury vapor

Some medical practitioners prescribe GSH and vitamin C alone or in combination with DMPS or DMSA for patients with mercury exposure that is primarily due to the mercury vapor emitted by dental amalgams.

HYPOTHESIS

This study tested the hypothesis that GSH, vitamin C, or lipoic acid alone or in combination with DMPS or DMSA would decrease brain mercury.

METHODS

Young rats were exposed to elemental mercury by individual nose cone, at the rate of 4.0 mg mercury per m3 air for 2 h per day for 7 consecutive days. After a 7-day equilibrium period, DMPS, DMSA, GSH, vitamin C, lipoic acid alone, or in combination was administered for 7 days and the brain and kidneys of the animals removed and analyzed for mercury by cold vapor atomic absorption.

RESULTS

None of these regimens reduced the mercury content of the brain. Although DMPS or DMSA was effective in reducing kidney mercury concentrations, GSH, vitamin C, lipoic acid alone, or in combination were not.

CONCLUSION

One must conclude that the palliative effect, if any, of GSH, vitamin C, or lipoic acid for treatment of mercury toxicity due to mercury vapor exposure does not involve mercury mobilization from the brain and kidney.

A patient with postoperative mercury contamination of the peritoneum

CASE REPORT

Peritoneal exposure to mercury has been rarely reported and long-term consequences of this type of exposure have not been documented. We report the clinical course of a patient who has survived almost eight years with a massive intraperitoneal load of mercury. She has suffered formication, pruritus, fatigue, irritiability, insomnia, alopecia, dizziness, a gait disturbance, loss of balance and multiple falls, abdominal pain, choking, and headaches. Two courses of chelation with dimercaptosuccinic acid using the standard protocol were undertaken, resulting in increased daily excretion, but without demonstrable objective or subjective benefit or lasting effect. She had multiple medical problems before the mercury intoxication, which complicates the attribution of all her problems to mercury intoxication. It is of particular interest that the patient survived and did not suffer any marked cognitive deterioration. She died in 2002 shortly after being diagnosed with lung cancer and declaring that she would fight it. Phasing out of mercury-weighted tubes is recommended.

Mercury exposure: current concepts, controversies, and a clinic's experience

In the context of controversies surrounding fish consumption, amalgams, and commercial hair testing, we reviewed all cases from an occupational and environmental medicine clinic that had undergone mercury testing. Sixty-nine of 71 (97%) patients had no known mercury exposures other than diet or amalgams. Of these 69, 48 had blood mercury tested and 58 had urine testing. Regular-to-heavy fish consumption explained 10 of 11 cases with blood mercury concentrations > 15 micrograms/L (19 to 53 micrograms/L). Six of these 10 individuals reported regular swordfish consumption. For the 31 patients with adequate dietary history, there was a significant relationship between fish consumption and blood mercury concentration (P < 0.001). Higher blood mercury concentrations were, however, not associated with specific patterns of health complaints. Ninety-eight percent (57 of 58) of urine values were < 10 micrograms/L. Fourteen patients were evaluated because they were labeled as mercury toxic by other practitioners after unconventional commercial testing. Using standard tests of blood and urine, we could not document evidence of mercury toxicity in any of these 14 cases. We conclude that consumption of commercially available fish can lead to elevated blood mercury concentrations. A recognized exposure source is a better predictor of significant mercury concentrations in biologic media than any particular symptom constellation. Unconventional commercial panels that test hair or urine for multiple metals have questionable validity. Clinicians should use standard blood and urine tests to evaluate mercury exposure.

Neuropsychological effects of low mercury vapor exposure in chloralkali workers

Neuropsychological effects were examined in 47 mercury vapor exposed male chloralkali workers with current low concentrations of urinary mercury (mean U-Hg 5.9 nmol/mmol creatinine (Cr)). Their average duration of exposure was 13.3 years, and the calculated mean concentration of U-Hg was 9.0 nmol Hg/mmol Cr per year (exposure intensity) during their time of exposure. They were compared with 47 age-matched male referents in a cross-sectional study. The two groups were not statistically significantly different with respect to neuropsychological test performance or number of self-reported subjective symptoms. The test results of the Static Steadiness Test, which assesses tremor, were not associated with exposure to mercury vapor. However current smokers had more hand tremor than non-smokers. Statistically significant associations were found between indices of current exposure (the concentration of inorganic mercury in whole blood) and the results of the WAIS Digit Symbol Test and the Benton Visual Retention Test (number of correct responses). This could indicate a small effect of current exposure on visuomotor/psychomotor speed and attention, and immediate visual memory. Whether the association found between the historical exposure intensity and the Digit Symbol Test results may represent long-term consequences of exposure cannot be determined in this study.

Health effects of long-term mercury exposure among chloralkali plant workers

BACKGROUND

Inorganic mercury is toxic to the nervous system, kidneys, and reproductive system. We studied the health effects of mercury exposure among former employees of a chloralkali plant that operated from 1955 to 1994 in Georgia.

METHODS

Former plant workers and unexposed workers from nearby employers were studied. Exposure was assessed with a job-exposure matrix based on historical measurements and personnel records. Health outcomes were assessed with interviews, physical examinations, neurological and neurobehavioral testing, renal function testing, and urinary porphyrin measurements. Exposure-disease associations were assessed with multivariate modeling.

RESULTS

Exposed workers reported more symptoms, and tended toward more physical examination abnormalities, than unexposed workers. Exposed workers performed worse than unexposed subjects on some quantitative tests of vibration sense, motor speed and coordination, and tremor, and on one test of cognitive function. Few findings remained significant when exposure was modeled as a continuous variable. Neither renal function nor porphyrin excretion was associated with mercury exposure.

CONCLUSIONS

Mercury-exposed chloralkali plant workers reported more symptoms than unexposed controls, but no strong associations were demonstrated with neurological or renal function or with porphyrin excretion.

Mercury exposure and cutaneous disease

Human contact with mercury has been ongoing for centuries and was previously considered a legitimate means of treating different cutaneous and systemic conditions. Toxicity from this heavy metal may occur from exposure to elemental, inorganic, and organic forms of mercury. This article outlines the signs and symptoms of mercury poisoning and the different clinical conditions with assorted cutaneous findings.