Epidemiology, clinical presentation, treatment, and follow-up of chronic mercury poisoning in China: a retrospective analysis.

BACKGROUND: There are no reports on the incidence of chronic mercury poisoning in a large population in China. This study investigated the epidemiology, clinical manifestations, treatment, and follow-up of Chinese patients with chronic mercury poisoning. METHODS: Data for 288 mercury poisoning patients were collected at our hospital from July 2014 to September 2019, including sex, age, admission time, blood mercury content, urine mercury content, creatinine, urinary mercury/creatinine ratio, 24-h urinary protein levels, electromyography (EMG) findings, renal biopsy, and follow-up. Patient characteristics were evaluated by statistical and correlation analyses. RESULTS: First, mercury poisoning in China mainly occurred through occupational exposure and the inappropriate use of mercury-containing cosmetics and Chinese folk remedies (CFRs). Second, the most common symptoms were nervous system (50.3 %), kidney (16.4 %) and breathing (8.0 %). Mercury poisoning-induced Nephrotic syndrome (NS) and peripheral neuropathy are common long-term complications. The complications of occupational and cosmetics-induced mercury poisoning are consistent with international belief. However, the NS caused by CFRs is mainly membranous nephropathy and the probability of peripheral neuropathy caused by CFRs is higher than other pathogens. Third, follow-up data shows that 13 patients with EMG-confirmed neurological injury, 10 showed full recovery after 38.50 ± 8.03 months. Furthermore, among 18 patients with NS, 15 had normal urine protein and serum albumin levels after 22.67 ± 10.26 months. CONCLUSIONS: Regulation of skin-lightening cosmetic products, safety surveillance of CFRs, and prevention and control of occupational exposure must be improved to decrease the incidence of mercury poisoning in China.

Blood and Urine Inorganic and Organic Mercury Levels in the United States from 1999 to 2016.

BACKGROUND: Mercury is an environmental hazard. Organic mercury is biologically more toxic than inorganic mercury. Therefore, we studied recent trends in the blood levels of organic and inorganic mercury in the United States. METHODS: A total of 56,445 participants that had blood mercury and urine mercury measurements in National Health and Nutrition Examination Survey (NHANES) 1999-2016 were included. The organic mercury level was obtained by subtracting the inorganic mercury level from the total mercury level. Results were analyzed using SPSS complex sample module version 25. Pregnant women, children ages <20 years, and different ethnicities were analyzed as subgroups. RESULTS: Blood organic mercury level increased from (geometric mean [95% confidence interval]) 0.08 [0.07-0.10] to 0.17 [0.16-0.18] µg/L during 1999-2016. It increased significantly (P <0.001) from 0.03 [0.02-0.03] to 0.07 [0.06-0.07] µg/L in children ages <20 and from 0.14 [0.09-0.21] to 0.36 [0.16-0.83] µg/L in pregnant women in this period (P <0.001). In 2013-2016, non-Hispanic Asians had the highest blood organic mercury level among different ethnicities, 0.93 [0.82-1.05] µg/L (P <0.001). Blood inorganic mercury level decreased from 0.31 [0.31-0.31] in 1999-2000 to 0.21 [0.21-0.22] µg/L in 2015-2016 (P <0.001). Urine mercury level decreased from 0.75 [0.71-0.80] in 1999-2000 to 0.16 [0.16-0.17] µg/L in 2015-2016 (P <0.001). CONCLUSION: Blood organic mercury increased over the period 1999-2016 in the US population, including children and pregnant women, whereas there was a steady decline in both blood inorganic mercury and urine mercury levels.

Association of Fish Consumption and Mercury Exposure During Pregnancy With Metabolic Health and Inflammatory Biomarkers in Children.

Importance: The balance of mercury risk and nutritional benefit from fish intake during pregnancy for the metabolic health of offspring to date is unknown. Objective: To assess the associations of fish intake and mercury exposure during pregnancy with metabolic syndrome in children and alterations in biomarkers of inflammation in children. Design, Setting, and Participants: This population-based prospective birth cohort study used data from studies performed in 5 European countries (France, Greece, Norway, Spain, and the UK) between April 1, 2003, and February 26, 2016, as part of the Human Early Life Exposome (HELIX) project. Mothers and their singleton offspring were followed up until the children were aged 6 to 12 years. Data were analyzed between March 1 and August 2, 2019. Exposures: Maternal fish intake during pregnancy (measured in times per week) was assessed using validated food frequency questionnaires, and maternal mercury concentration (measured in micrograms per liter) was assessed using maternal whole blood and cord blood samples. Main Outcomes and Measures: An aggregate metabolic syndrome score for children was calculated using the z scores of waist circumference, systolic and diastolic blood pressures, and levels of triglyceride, high-density lipoprotein cholesterol, and insulin. A higher metabolic syndrome score (score range, -4.9 to 7.5) indicated a poorer metabolic profile. Three protein panels were used to measure several cytokines and adipokines in the plasma of children. Results: The study included 805 mothers and their singleton children. Among mothers, the mean (SD) age at cohort inclusion or delivery of their infant was 31.3 (4.6) years. A total of 400 women (49.7%) had a high educational level, and 432 women (53.7%) were multiparous. Among children, the mean (SD) age was 8.4 (1.5) years (age range, 6-12 years). A total of 453 children (56.3%) were boys, and 734 children (91.2%) were of white race/ethnicity. Fish intake consistent with health recommendations (1 to 3 times per week) during pregnancy was associated with a 1-U decrease in metabolic syndrome score in children (ß = -0.96; 95% CI, -1.49 to -0.42) compared with low fish consumption (<1 time per week) after adjusting for maternal mercury levels and other covariates. No further benefit was observed with fish intake of more than 3 times per week. A higher maternal mercury concentration was independently associated with an increase in the metabolic syndrome score of their offspring (ß per 2-fold increase in mercury concentration = 0.18; 95% CI, 0.01-0.34). Compared with low fish intake, moderate and high fish intake during pregnancy were associated with reduced levels of proinflammatory cytokines and adipokines in children. An integrated analysis identified a cluster of children with increased susceptibility to metabolic disease, which was characterized by low fish consumption during pregnancy, high maternal mercury levels, decreased levels of adiponectin in children, and increased levels of leptin, tumor necrosis factor α, and the cytokines interleukin 6 and interleukin 1ß in children. Conclusions and Relevance: Results of this study suggest that moderate fish intake consistent with current health recommendations during pregnancy was associated with improvements in the metabolic health of children, while high maternal mercury exposure was associated with an unfavorable metabolic profile in children.

Insights into the Potential Role of Mercury in Alzheimer's Disease.

Mercury (Hg), which is a non-essential element, is considered a highly toxic pollutant for biological systems even when present at trace levels. Elevated Hg exposure with the growing release of atmospheric pollutant Hg and rising accumulations of mono-methylmercury (highly neurotoxic) in seafood products have increased its toxic potential for humans. This review aims to highlight the potential relationship between Hg exposure and Alzheimer's disease (AD), based on the existing literature in the field. Recent reports have hypothesized that Hg exposure could increase the potential risk of developing AD. Also, AD is known as a complex neurological disorder with increased amounts of both extracellular neuritic plaques and intracellular neurofibrillary tangles, which may also be related to lifestyle and genetic variables. Research reports on AD and relationships between Hg and AD indicate that neurotransmitters such as serotonin, acetylcholine, dopamine, norepinephrine, and glutamate are dysregulated in patients with AD. Many researchers have suggested that AD patients should be evaluated for Hg exposure and toxicity. Some authors suggest further exploration of the Hg concentrations in AD patients. Dysfunctional signaling pathways in AD and Hg exposure appear to be interlinked with some driving factors such as arachidonic acid, homocysteine, dehydroepiandrosterone (DHEA) sulfate, hydrogen peroxide, glucosamine glycans, glutathione, acetyl-L carnitine, melatonin, and HDL. This evidence suggests the need for a better understanding of the relationship between AD and Hg exposure, and potential mechanisms underlying the effects of Hg exposure on regional brain functions. Also, further studies evaluating brain functions are needed to explore the long-term effects of subclinical and untreated Hg toxicity on the brain function of AD patients.

Mercury-induced Oxidative Stress May Adversely Affect Pregnancy Outcome among Dental Staff: A Cohort Study.

BACKGROUND: Dental staff may be at increased risk of adverse pregnancy outcome secondary to their chronic exposure to mercury. OBJECTIVE: To investigate obstetric outcome among dental staff and explore the oxidative stress induced by mercury exposure. METHODS: A cohort of 64 pregnant dental staff (exposed group) and 60 pregnant employees (non-exposed group) were studied. Urinary mercury level and blood antioxidant activity were measured. Participants were followed to assess their obstetric outcome. RESULTS: The exposed group had a higher mean urinary mercury level and a lower blood antioxidant activity during the three trimesters compared to non-exposed group (p<0.001). Women in the exposed group were experienced more frequently spontaneous abortion and pre-eclampsia (p<0.05). Babies born to the women in the exposed group tended to be smaller for gestational age compared to those of non-exposed group (p<0.001). CONCLUSION: Pregnant dental staff suffered higher odds of developing spontaneous abortion and pre-eclampsia and giving birth to babies smaller for gestational age. This may be linked to oxidative stress induced by exposure to mercury.

Regresión autista: aspectos clínicos y etiológicos / Autistic regression: clinical and aetiological aspects

Introducción. Los trastornos del espectro autista son disfunciones del neurodesarrollo que se caracterizan por déficits en la integración social y la comunicación, asociados a intereses restringidos y conductas estereotipadas. Un alto porcentaje se asocia a trastorno del lenguaje, disfunciones sensoriales, trastorno por déficit de atención, bipolaridad, discapacidad intelectual o epilepsia, entre otras comorbilidades. Se estima que aproximadamente un 30% de los niños con autismo, con desarrollo típico inicial, pueden presentar regresión en los primeros años de vida, lo cual ya fue comunicado por Kanner en uno de sus casos originales. Se denomina regresión a la pérdida de habilidades sociales, comunicativas o motoras. Es esencial estar atentos ante cualquier cuadro de regresión autista, ya que no siempre es una manifestación habitual inespecífica del espectro clínico de autismo. Si bien la patogenia de la regresión se comprende poco, debe ser jerarquizada, ya que puede ser parte de diferentes entidades con diversas etiologías. Objetivo. Analizar diferentes entidades que deben evocarse frente a un niño con regresión autista, incluyendo etiologías genéticas, tóxicas, fenómenos autoinmunes, nutricionales y epilepsias. Conclusión. Frente a un cuadro de regresión autista es esencial intentar identificar (AU)

Introduction. Autism spectrum disorders are neurodevelopmental dysfunctions that are characterised by deficits in social integration and communication, associated with restricted interests and stereotypic behaviour. A high percentage are related to language disorders, sensory dysfunctions, attention deficit disorder, bipolarity, intellectual disability or epilepsy, among other comorbidities. It is estimated that around 30% of children with autism, with typical early development, may present regression in the first years of life, which was already reported by Kanner in one of his original cases. The term regression refers to the loss of social, communicative or motor skills. It is essential to be alert to any symptoms of autistic regression, since it is not always an unspecific usual manifestation of the clinical spectrum of autism. Although little is known about the pathogenesis of regression, it needs to be organised hierarchically, as it can be part of different conditions with a variety of causes. Aims. The aim of this study is to analyse distinct conditions that need to be addressed in the case of a child with autistic regression, including genetic and toxic causations, autoimmune and nutritional phenomena, and epilepsies. Conclusion. When faced with a case of autistic regression it is essential to try to identify the possible aetiology, as this can allow specific treatment and adequate genetic counselling to be established (AU)

Vulnerability associated with "symptoms similar to those of mercury poisoning" in communities from Xingu River, Amazon basin.

The Brazilian Amazon is known to be a region with high levels of mercury (Hg) in the environment and studies point to an association between high levels of natural mercury in the mother rock and the vast number of clandestine gold mines. Other studies already report the contamination of fish in this region, as well as high levels of Hg in biological material from environmentally exposed populations. On the other hand, this is one of the least developed regions of the planet and it is necessary to understand the vulnerability factors in these populations that may be intoxicated by this element. The purpose of the present study was to investigate the vulnerability factors in communities from Xingu River-Amazon basin probably exposed to Hg. A cross-selection study in two cities localized in Xingu River was conducted, and the sample contained was 268 individuals. sociodemographic questions, lifestyle, diet habits and health conditions were collated. The majority of the sample was female, between 30 and 59 years old, had less than 3 years of educational level and lived in the local of study more than 240 months. There was regular fish consumption (95.9%), principally carnivorous species (80.5%). The visual problem has a highest prevalence (43.3%) between the health problems and about the symptoms of Hg intoxication, memory loss (42.9%), weakness (35.1%), fatigue (34.3%), mood changes (28.7%) and difficulties in concentration (27.2%) was most reported. The female sex, age over 60, educational level below 3 years of study, did not had flush toilet, smoke and least one chronic non-communicable disease represent higher probability to had symptoms of Hg intoxication. Lack of access to health services, low education level and income evidence the susceptibility of this community to diseases and injuries. The vulnerable groups identified in this study should be a priority in public health and environmental health policies.

The chicken excrete intoxication in fattening cattle of European breeds / Intoxicación por pollinaza en ganado de engorde de razas europeas

In Mexico, there is not enough information about cattle poisoning. A clinical case in a feedlot in Michoacán, Mexico, is described. In November 2017, 35 out 130 bulls were affected (27%), with clinical signs of anorexia, diarrhea, tachycardia, tachypnea, incoordination, low weight gain and corneal opacity. Animals were fed with grains (50%), chicken manure (35%), soybean paste (10%) vitamins, mineral salts (5%) and roughage. The initial treatment consisted of antibiotics and vitamins; after 3 weeks, without a clear improvement, antihistamines and hepatic modulators were added. Three months later, seventeen animals became blind, and the rest showed recovery. It was not possible to perform a necropsy or collection of organ samples, just samples of chicken excrete and water were collected for lead (Pb), mercury (Hg), chromium (Cr), copper (Cu), arsenic (As) and cadmium (Cd) determination by the atomic absorption spectrophotometry technique coupled to a flame detector and also phosphorus and sulfates were determined by UV light spectrometry. The clinical diagnosis was intoxication due to excess of chicken excrete into diet joined with metallic elements present in drinking water. It is concluded an acute poisoning by excess of ammonia, copper, arsenic and mercury in young bovines by contaminated water and chicken excrete

En México no existe suficiente información sobre intoxicaciones en el ganado. Se describe un caso clínico ocurrido en una engorda de bovinos en el estado de Michoacán, durante el invierno 2017. De un total de 130 bovinos, 35 de ellos enfermaron (27%), todos de raza europea. Al exámen clinico los enfemos mostraron, anorexia, diarrea, taquicardia, taquipnea, incoordinación, fasciculaciones musculares y diecisite bovinos opacidad de córnea. La alimentación de los animales compuesta por granos de cereales (50%), pollinaza (35%), pasta de soja (10%), vitaminas y sales minerales (5%) y forraje seco. Se sospechó de una intoxicación por pollinaza y de alguna infección gastroentérica. Se ofreció un tratamiento a base de abtibióticos y vitaminas ADE, después de tres semanas y sin una clara mejoría se indicó la adición de un antihistaminico y hepatonico. No fue posible realizar ninguna necropsia ni colectar tejidos para su estudio histopatológico, utilizando muestras de la pollinaza y del agua para remitirlos al laboratorio de toxicología de la Universidad, para esclarecer el diagnóstico. Se realizaron análisis de cobre (Cu), plomo (Pb), mercurio (Hg), chromo (Cr), arsenico (As) y cadmio (Cd), mediante la técnica de espectroscopía de absorción atómica acoplada a un detector de flama y la espectrofotometria de luz ultravioleta para el fósforo y sulfatos. Los resultados del laboratorio mostrsaron niveles de cobre en la pollinaza inusuales y en el agua elementos metálicos. Tres meses después los animales se recuperaron. Se concluye una intoxicación aguda por exceso de amonio, cobre, arsénico y mercurio

[Taki Onqoy: mercury poisoning epidemic in 16TH century Huamanga]. / Taki Onqoy: epidemia de intoxicación por exposición al mercurio en Huamanga del siglo XVI.

Taki Onqoy is a syndrome that corresponds to the poisoning from exposure to mercury. It appeared as a result of the exploitation of the mercury mines of Paras and Huancavelica in Peru during the 16th century. The Cachexia mercurial, the last stage of the disease, would be associated with the idea of pishtaco. The Taki Onqoy in 16th-century Peru represents the largest epidemic of mercury poisoning known to humanity.

Taki Onqoy es un síndrome que corresponde a la intoxicación por exposición al mercurio. Apareció como consecuencia de la explotación de las minas de mercurio de Paras y Huancavelica en el Perú durante el siglo XVI. La caquexia mercurial, última etapa de la enfermedad, estaría asociada a la idea del pishtaco. El Taki Onqoy en el Perú del siglo XVI, representa la mayor epidemia por intoxicación por mercurio conocida por la humanidad.

Global Burden of Disease of Mercury Used in Artisanal Small-Scale Gold Mining.

BACKGROUND: Artisanal small-scale gold mining (ASGM) is the world's largest anthropogenic source of mercury emission. Gold miners are highly exposed to metallic mercury and suffer occupational mercury intoxication. The global disease burden as a result of this exposure is largely unknown because the informal character of ASGM restricts the availability of reliable data. OBJECTIVE: To estimate the prevalence of occupational mercury intoxication and the disability-adjusted life years (DALYs) attributable to chronic metallic mercury vapor intoxication (CMMVI) among ASGM gold miners globally and in selected countries. METHODS: Estimates of the number of artisanal small-scale gold (ASG) miners were extracted from reviews supplemented by a literature search. Prevalence of moderate CMMVI among miners was determined by compiling a dataset of available studies that assessed frequency of intoxication in gold miners using a standardized diagnostic tool and biomonitoring data on mercury in urine. Severe cases of CMMVI were not included because it was assumed that these persons can no longer be employed as miners. Cases in workers' families and communities were not considered. Years lived with disability as a result of CMMVI among ASG miners were quantified by multiplying the number of prevalent cases of CMMVI by the appropriate disability weight. No deaths are expected to result from CMMVI and therefore years of life lost were not calculated. Disease burden was calculated by multiplying the prevalence rate with the number of miners for each country and the disability weight. Sensitivity analyses were performed using different assumptions on the number of miners and the intoxication prevalence rate. FINDINGS: Globally, 14-19 million workers are employed as ASG miners. Based on human biomonitoring data, between 25% and 33% of these miners-3.3-6.5 million miners globally-suffer from moderate CMMVI. The resulting global burden of disease is estimated to range from 1.22 (uncertainty interval [UI] 0.87-1.61) to 2.39 (UI 1.69-3.14) million DALYs. CONCLUSIONS: This study presents the first global and country-based estimates of disease burden caused by mercury intoxication in ASGM. Data availability and quality limit the results, and the total disease burden is likely undercounted. Despite these limitations, the data clearly indicate that mercury intoxication in ASG miners is a major, largely neglected global health problem.

Taki Onqoy: epidemia de intoxicación por exposición al mercurio en Huamanga del siglo XVI / Taki Onqoy: mercury poisoning epidemic in 16TH century Huamanga

RESUMEN Taki Onqoy es un síndrome que corresponde a la intoxicación por exposición al mercurio. Apareció como consecuencia de la explotación de las minas de mercurio de Paras y Huancavelica en el Perú durante el siglo XVI. La caquexia mercurial, última etapa de la enfermedad, estaría asociada a la idea del pishtaco. El Taki Onqoy en el Perú del siglo XVI, representa la mayor epidemia por intoxicación por mercurio conocida por la humanidad.

ABSTRACT Taki Onqoy is a syndrome that corresponds to the poisoning from exposure to mercury. It appeared as a result of the exploitation of the mercury mines of Paras and Huancavelica in Peru during the 16th century. The Cachexia mercurial, the last stage of the disease, would be associated with the idea of pishtaco. The Taki Onqoy in 16th-century Peru represents the largest epidemic of mercury poisoning known to humanity.

Immunotoxicity of mercury: Pathological and toxicological effects.

Mercury (Hg) is toxic and hazardous metal that causes natural disasters in the earth's crust. Exposure to Hg occurs via various routes; like oral (fish), inhalation, dental amalgams, and skin from cosmetics. In this review, we have discussed the sources of Hg and its potential for causing toxicity in humans. In addition, we also review its bio-chemical cycling in the environment; its systemic, immunotoxic, genotoxic/carcinogenic, and teratogenic health effects; and the dietary influences; as well as the important considerations in risk assessment and management of Hg poisoning have been discussed in detail. Many harmful outcomes have been reported, which will provide more awareness.

Comparison of single- and multiple-person mercury exposures.

Elemental and organic mercury are extremely toxic. All mercury exposures reported to Texas poison centers during 2000-2013 were identified. The cases were divided into multiple- and single-person exposure groups and compared, including identification of statistically significant differences (SSDs). There were 6,521 single-person exposures and 214 multiple-person incidents involving 734 total persons; 45% and 27% of the multiple- and single-person exposures, respectively, involved patients aged 6-19 years (SSD). The multiple- and single-person exposures were, respectively, 87% vs 98% unintentional (SSD). The most frequent routes of multiple- and single-person exposures, respectively, involved ingestion (23% vs 72%, SSD), dermal (52% vs 23%, SSD), and inhalation (43% vs 5%, SSD). The most common site for multiple- and single-person exposures was the patient's own residence (56% vs 91%, respectively, SSD). Multiple-person mercury exposures are more likely to involve school-age children. A greater proportion of multiple-person exposures was intentional, involved dermal and inhalation routes, and occurred at school.

Erring on the side of caution: pregnant women's perceptions of consuming fish in a risk averse society.

BACKGROUND: Fish and seafood are good sources of several nutrients that are important for foetal growth and development. Despite guidelines encouraging the eating of fish during pregnancy, research indicates that pregnant women may be limiting or avoiding these foods. Possible factors contributing to this include concerns regarding levels of mercury and other contaminants and pregnant women's purported heightened risk consciousness. The present study aimed to explore pregnant women's perceptions of consuming fish and seafood during pregnancy. METHODS: Semi-structured telephone interviews were conducted with 15 pregnant women across all three trimesters in New South Wales, Australia. Questions focussed on exploring nutrition information received during pregnancy, dietary changes made during pregnancy and, more specifically, perceptions of fish and seafood, as well as views on information of fish and seafood commonly provided to pregnant women. Data were collected, then transcribed and analysed using an inductive coding process, guided by the qualitative theory grounded approach. RESULTS: Multiple inter-related themes were found to shape pregnant women's perceptions related to fish and seafood consumption during pregnancy; namely, the understanding of fish and seafood as part of a healthy diet, external factors such as cost, individual preferences such as taste, and confidence in choosing and preparing fish. The context of a risk adverse society permeated these themes. CONCLUSIONS: The present study provides insight into the inter-related factors that influence pregnant women's consumption or avoidance of fish and seafood.

Mercury distribution in organs of fish species and the associated risk in traditional subsistence villagers of the Pantanal wetland.

This study evaluated the risk to human health from mercury (Hg) exposure through fish consumption in the Pantanal, Brazil. In order to address these risks, Hg concentrations and accumulation patterns were determined in target organs of predatory fish (Crenicichla lepidota and Pygocentrus nattereri). Levels of Hg were analysed during the two phases of the flood pulse (flood and drought) in fish from different local ecosystems, such as the Bento Gomes and Paraguay rivers. Although the former study area is directly affected by gold mining, a higher, but not significantly different, Hg concentration in fish was found compared with fish at the Paraguay River, which is regarded as pristine area. Moreover, no seasonal variability was found in either river. Although total mercury levels in fish did not exceed the maximum FAO/WHO threshold (0.5 µg g(-1)), according to dietary habits in riverine communities of the Pantanal (up to 6 oz of fish per day), there is reason for concern over the potential for deleterious health effects that could be caused by high Hg intake. In fact, the estimated daily intake in the present study ranged from 0.49 to 1.08 µg Hg kg(-1) day(-1), for adults (including women of childbearing age) and children, respectively. Because of high Hg intakes in riverine groups, which exceed the recommended reference dose value, these communities could be considered at risk. Therefore, it is necessary to consider regulatory measures and public education regarding fish consumption, particularly in vulnerable groups (i.e. children, pregnant women and women of childbearing age).

Mercury Toxicity and Contamination of Households from the Use of Skin Creams Adulterated with Mercurous Chloride (Calomel).

Inorganic mercury, in the form of mercurous chloride, or calomel, is intentionally added to some cosmetic products sold through informal channels in Mexico and the US for skin lightening and acne treatment. These products have led to multiple cases of mercury poisoning but few investigations have addressed the contamination of cream users' homes. We report on several cases of mercury poisoning among three Mexican-American families in California from use of mercury-containing skin creams. Each case resulted in widespread household contamination and secondary contamination of family members. Urine mercury levels in cream users ranged from 37 to 482 µg/g creatinine and in non-users from non-detectable to 107 µg/g creatinine. Air concentrations of up to 8 µg/m³ of mercury within homes exceeded the USEPA/ATSDR health-based guidance and action level of <1.0 µg/m³. Mercury contamination of cream users' homes presented a multi-pathway exposure environment to residents. Homes required extensive decontamination, including disposal of most household items, to achieve acceptable air levels. The acceptable air levels used were not designed to consider multi-pathway exposure scenarios. These findings support that the calomel is able to change valence form to elemental mercury and volatilize once exposed to the skin or surfaces in the indoor environment.

Occupational mercury exposure in association with prevalence of multiple sclerosis and tremor among US dentists.

BACKGROUND: The effects of chronic occupational exposure to elemental mercury (Hg(0)) are largely unknown. The objective was to evaluate the association of occupational Hg(0) exposure with multiple sclerosis (MS) and tremor. METHODS: The study included 13,906 dentists who attended the American Dental Association's annual meeting over 24 years (1986-2007 and 2011-2012). Participants reported MS and tremor and provided urine specimens for Hg(0) analysis. The authors estimated mean Hg(0) exposures over time and used logistic regression to estimate the associations of 3 Hg(0) exposure measures with MS or tremor. RESULTS: Among participants, 0.18% reported MS and 1.24% reported tremor. Hg(0) exposure was not associated with MS (odds ratio [OR] per 191 micrograms per liter in cumulative Hg(0) exposure, 0.85; 95% confidence interval [CI], 0.39-1.85). Increased prevalent risk of tremor was found with exposure to both urinary Hg(0) exposure (OR, 1.10 [95% CI, 1.00-1.22]) and cumulative Hg(0) exposure among younger dentists (< 51 years; OR, 1.13 [95% CI, 1.05-1.22]). CONCLUSIONS: Occupational Hg(0) exposure in US dentists decreased over time and now is approaching that of the general population. Our results suggest a positive association between Hg(0) exposure and tremor. PRACTICAL IMPLICATIONS: Studies with more sophisticated outcome and exposure measures, and including more retired dentists, would provide critical information toward understanding the relation of Hg(0) exposures to MS and tremor risk.