Examination of urinary mercury levels in dentists in Turkey

Mercury (Hg) is a naturally occurring element and its toxicity, especially in certain forms, has been known for many years. Exposure to Hg can occur in occupational and environmental settings. The toxicity of Hg compounds in dentistry has been an issue of increasing concern. Dental personnel are occupationally exposed to Hg vapor in their working environment and this exposure constitutes a potential risk to people in the dental surgery, mainly from the inhalation of Hg vapor and fine particles of amalgam. In this study, the urinary Hg excretion levels of 20 dentists and nine control subjects, matched for age, were determined by cold-vapor atomic absorption spectrometer (CV-AAS). The levels of Hg in the urine samples of the dentists was about three times higher than the control subjects (6.2 +/- 3.5 and 1.97 +/- 0.9 microg/L, respectively) (P <0.001). Some 90% of dentists wore both gloves and masks. Standards of hygiene (use of mask, glove and gown) may contribute to the degree of exposure. Attention to important hygiene measures, such as the avoidance of spills of Hg, cleaning of floors after such spills, ventilation and the installation of ventilation, depending on technology, should be taken into consideration. Age and smoking habits did not influence the urinary Hg excretion. Our results showed that dentists had significant exposure to Hg vapor compared to control subjects and therefore might be subject to possible adverse effects due to Hg toxicity.     

Glutathione enzyme and selenoprotein polymorphisms associate with mercury biomarker levels in Michigan dental professionals

Mercury is a potent toxicant of concern to both the general public and occupationally exposed workers (e.g., dentists). Recent studies suggest that several genes mediating the toxicokinetics of mercury are polymorphic in humans and may influence inter-individual variability in mercury accumulation. This work hypothesizes that polymorphisms in key glutathione synthesizing enzyme, glutathione s-transferase, and selenoprotein genes underlie inter-individual differences in mercury body burden as assessed by analytical mercury measurement in urine and hair, biomarkers of elemental mercury and methylmercury, respectively. Urine and hair samples were collected from a population of dental professionals (n = 515), and total mercury content was measured. Average urine (1.06 ± 1.24 ug/L) and hair mercury levels (0.49 ± 0.63 ug/g) were similar to national U.S. population averages. Taqman assays were used to genotype DNA from buccal swab samples at 15 polymorphic sites in genes implicated in mercury metabolism. Linear regression modeling assessed the ability of polymorphisms to modify the relationship between mercury biomarker levels and exposure sources (e.g., amalgams, fish consumption). Five polymorphisms were significantly associated with urine mercury levels (GSTT1 deletion), hair mercury levels (GSTP1-105, GSTP1-114, GSS 5′), or both (SEPP1 3′UTR). Overall, this study suggests that polymorphisms in selenoproteins and glutathione-related genes may influence elimination of mercury in the urine and hair or mercury retention following exposures to elemental mercury (via dental amalgams) and methylmercury (via fish consumption).     

Methylmercury exposure, mercury levels in blood and hair, and health status in Swedes consuming contaminated fish

Levels of total mercury in blood cells ranging 8–390 ng/g (in one case 1100) were found in 162 Swedes who consumed fish containing 0.3–7 mg Hg/kg. Levels above 100 ng/g were seen only in subjects 40–80 years of age, levels above 200 ng/g only in persons who consumed fish containing about 1 mg Hg/kg or more. 20 subjects eating fish containing about 0.04 mg Hg/kg ranged 8–45 ng/g blood cells, and 22 subjects eating commercially available fish 3–57 ng/g. Long-term exposure to 4 μg Hg as methylmercury/kg body weight/day - as estimated from fish intake records - corresponded to a blood cell mercury level of about 300 ng/g. After the end of exposure, biologic half-time of mercury in blood cells ranged 58–87 days in 4 subjects, while the corresponding figure was 164 days in one individual. A screening for signs and symptoms of methylmercury poisoning in 86 of the exposed subjects revealed no clearcut case of poisoning. Some subjects of symptoms in a high-mercury (82–1100 ng/g blood cells) group as compared to a low-mercury (12–75 ng/g) group.     

Impact of consumption of freshwater fish on mercury levels in hair, blood, urine, and alveolar air

Human exposure to methylmercury occurs mainly via consumption of fish. The aim of the study was to investigate the influence of freshwater fish consumption on mercury levels in hair, blood, urine, and end-exhaled air. Twenty subjects without dental amalgam fillings were recruited from sport-fishing societies. They ranged in age from 61 to 87 yr. Six individuals ate freshwater fish at least once a week and were categorized as high consumers. Eight individuals were classified as medium consumers and ate freshwater fish at least once a month but less than once a week. Six individuals were categorized as low consumers and had not eaten freshwater fish in the past 3 mo. Among the high consumers, median concentrations of mercury were 8.6 microg/L in blood, 2.4 microg/g in hair, 10 pg/L in end-exhaled air, and 1.1 microg/g creatinine in urine. The relationship between freshwater fish consumption and mercury was significant in all biological media. The high-consumption group had much higher mercury levels in blood (9-fold), hair (7-fold), alveolar air (3-fold), and urine (15-fold) than the low-consumption group. The latter finding may be explained by demethylation of methylmercury in the body. The ratio between mercury concentration in blood and hair was 1:270. This implies that the typical blood-hair ratio of 1:250, specified by the World Health Organization (WHO) in 1990, is valid also for exposure to low amounts of methylmercury.     

The assessment of the contribution of hair to methyl mercury excretion

Due to its ability to avidly accumulate methyl mercury from blood, scalp hair has been widely used as a biological monitor for human exposure. The question arises that hair may also be an important route of elimination of methyl mercury from the body. Taking original publications and reviews on the physiology of hair (including growth by weigh and density) and on the deposition parameters for methyl mercury in the body (including the hair to blood concentration ratio of methyl mercury), one can calculate the rate of elimination of methyl mercury in hair. The result indicates that hair accounts for only a small fraction, less than 10%, of the total elimination of methyl mercury from the body. This relationship is expected to be maintained at every level when the dominant form of mercury is methyl. Other species of mercury I eliminated by hair even at a lower rate.     

Validity of methyl mercury hair analysis: mercury monitoring in human scalp/nude mouse model

OBJECTIVE: The grafting of human scalp hair was used as a new application of this method to explore methyl mercury incorporation into human hair and to validate this model for mercury monitoring in hair. METHODS: Human scalp grafts were transplanted to athymic BALB/c nude mice. The animals were exposed to methyl mercury either as a single dose i.p. or continuously for 4 months, using ALZET osmotic pumps. The mercury concentration in hair was determined using x-ray fluorescence (XRF) spectrometry by segmental (2 mm) analysis of a single strand, and tissue concentrations were measured by cold vapor atomic absorption analysis. RESULTS: Human scalp hair grown in nude mice showed long-term persistence of human features including the expression of histocompatibility antigens (KAB 3, W 6/32, SF 1-1.1.1) and normal hair morphometry. The disposition of methyl mercury in nude mice followed a one-compartment model with a whole body elimination half-life of 6.7 days (elimination constant, k = 0.1/day). Autoradiographic studies revealed that methyl mercury was rapidly incorporated into areas of the hair follicle undergoing active keratinization. Methyl mercury concentrations in human hair transplanted onto nude mice were two orders of magnitude higher than in blood and attained a mean hair: blood ratio of 217 : 1, similar to ratios reported only in human studies. CONCLUSIONS: This study demonstrated that human hair grown on nude mice can record the level of exposure to methyl mercury and can serve as a valuable research tool to study mercury incorporation into human hair.     

松花江同江江段渔民发汞值调查

本文对松花江同江江段沿江渔民于1990年4月进行头发总汞值调查。调查结果,渔民发汞值中位数为2.574ppm。处于受汞污染状态,即4ppm以上者仅占24.46％。没有超过10ppm者。     

A comparison of treatment effectiveness of nonaddict and exaddict professionals in an adolescent treatment program

This paper examines the relative effectiveness of the nonaddict professional and the exaddict professional in an adolescent drug abuse treatment program. Based upon statistical and clinical considerations, the authors' conclusion is that exaddict professionals untrained in psychology or a related health field should perhaps not work with adolescents who present with drug and mental health problems.Strengths and weaknesses of each group are discussed, as is clinical effectiveness with respect to client retention and discharge rates. Age, race and sex were explored relative to length of employment. It was found that exaddict professionals left work significantly more often than nonaddict professionals as a result of negative or unethical behavior.     

Normal and lethal mercury levels in human beings

Ethyl mercury in the form of Granosan M was used as a fungicide in dressing grains in Iraq. Disregarding warnings and precautions by the authorities, some villagers used this grain in making their bread.Tissue specimens of poisoned people were analysed for total mercury contents using the flameless atomic absorption spectroscopic technique. The analytical method used is highly sensitive 91 ppb/1% absorbence), and the precision in terms of relative standard deviation (RSD) was about 1.5%.The ranges of mercury content in ppm units in the two cases of poisoning were 8–9 for the kidneys, 6–7 for livers, 3–5 for the cerebella, and about 15 for the blood. The analyses included some other tissues as well.Control values were also present. These were obtained from human beings who died by accident and showed no signs of mercury poisoning.     

无机汞在鲤鱼体内生物富集规律的研究

50—60年代，日本的水俣湾汞污染及新泻市相继发生水俣病事件，原因是渔民长期食用的鱼体内含有甲基汞，它由水体中的无机汞转化而成，通过生物的富集作用和食物链传递的生物放大作用，最后在食用者体内积累，以致中毒发病，严重者终至死亡。随后，瑞典的卡夫里、瓦斯特瑙克海域、鲁地维卡湖、加拿大的瓦比冈-温尼伯格河水系以及美国的五大湖和瓦特科河都相继报道过汞污染。     

Integrating variability in half-lives and dietary intakes to predict mercury concentration in hair

Methylmercury (MeHg) is a bioaccumulative environmental toxin that exerts its effect on fetal and infant neurodevelopment. Mercury concentration in hair is a good biomarker of MeHg accumulation in the body, with seafood being the main source of MeHg in humans. Therefore, modeling the link between food intake and mercury concentration in hair is a key step in assessing the risk of MeHg exposure. Using repeated measurements of diet and mercury concentration in hair, we studied 125 French pregnant women who consumed seafood (e.g., fish, mollusks and crustaceans) and compared their individual estimated dietary MeHg intakes with their hair mercury concentrations. We used a one-compartment toxicokinetic model for these comparisons. We integrated and estimated the between-person variability in MeHg half-life into the model. In a second model, we took into account an intra-individual MeHg intake variability to improve the performance of the toxicokinetic model.     

DHEA and DHEA-S levels in hospitalized adolescents with first-episode schizophrenia and conduct disorder: A comparison study

IntroductionIncreasing evidence exists indicating an association of DHEA and DHEA-S blood levels with psychosis, however many of the findings remain contradictory based on different phases of the illness, different treatments and at a range of ages. To date no studies exist investigating the levels of these neurosteroids in adolescents with psychosis. Such an investigation would be important in order to exclude effects of chronic illness, long-term treatment and repeated hospitalizations.MethodPeripheral venous blood samples for DHEA, DHEA-S and cortisol determination were collected from first-time hospitalized adolescents with diagnoses of schizophrenia as well as from patients with conduct disorder. Patients were rated with the Positive and Negative Syndrome Scale (PANSS), the Hamilton Scale for depression (HAM-D), the Overt Aggression Scale (OAS) and the impulsivity scale (IS).ResultsDHEA levels in adolescents with schizophrenia were significantly higher than in patients with conduct disorder (p = 0.002). Blood levels of DHEA and DHEA-S in schizophrenia correlated with the total PANSS scores (both p < 0.05). No correlations were detected between any of the neurosteroid blood levels and clinical rating scales in the control group.ConclusionsIt may be proposed that individuals in their early stages of schizophrenia psychosis may develop a protective or compensatory neurosteroid response to the first onset of psychosis. Such a putative upregulatory DHEA mechanism may become desensitized with progression to chronic illness. The temporal relationship of investigation of neurosteroid levels in adolescents compared to such investigation in adults may provide important and relevant information.     

An observation on the mercury contents of scalp hair in the urban residents of South Korea

The average value of total mercury (THg) in scalp hair of male residents in Seoul city was 1.7±0.18 ppm (mean±S.E.) and that of methylmercury (MeHg), 1.0±0.12 ppm (58.8% THg). In female, level of THg was 1.1±0.15 ppm and MeHg was 0.5±0.14 ppm (45.5%). Mercury was found more in the scalp hair of male than female (P<0.01). THg/MeHg increased with age of subjects in male (P<0.01), but not female. Coefficients of correlation (r) between THg and MeHg contents in scalp hair of male was +0.877 (P<0.01) and that of female was +0.508 (P<0.01), respectively.     

Distribution of mercury in rabbits subchronically exposed to low levels of radiolabeled methyl mercury

The metabolism of methyl mercury (MeHg) has been studied in rabbits administered 203Hg-labeled methyl mercuric chloride, 0.125 mumol/kg body weight, twice a week for 9 weeks, by intravenous injection. Twelve weeks after cessation of treatment, about 54% of the administered dose had been excreted in faeces and 5% in urine. After one week, the highest concentration of 203Hg was found in fur (8.6 nmol Hg/g). Substantially lower concentrations were found in kidney (2.5 nmol/g), liver (0.9 nmol/g), brain (0.4 nmol/g), muscle (0.3 nmol/g) and blood (0.1 nmol/g). The rate of elimination of 203Hg from brain, muscle and blood was faster (t1/2 about 12 days) than that from kidney and liver (t1/2 about 28 days). The relative amount of inorganic Hg in kidney and liver increased with time after cessation of treatment. The highest fractions were 85 and 70%, respectively. In brain, no significant demethylation of MeHg could be detected.     

Total mercury in the hair of children by combustion atomic absorption spectrometry (Comb-AAS)

A simple and rapid procedure for measuring total mercury in human hair was evaluated and compared with a conventional technique. An Advanced Mercury Analyzer (AMA-254) based on sample catalytic combustion, preconcentration by gold amalgamation, thermal desorption, and atomic absorption spectrometry (AAS) (Comb-AAS) was assessed for the direct determination of milligram quantities of human hair. Precision (% relative standard deviation) was < 7% and accuracy was determined by using two human hair reference materials (i.e., NIES No. 13 and IAEA-086) that were within the certified range. In comparison to conventional graphite-furnace atomic absorption spectrophotometry (GF-AAS), we found that our method obtained statistically equivalent results. Because total analysis time per sample was less than 10 min, the Comb-AAS method was in fact much faster than the GF-AAS method. In addition, Comb-AAS does not generate waste products and could be mainly useful for the analysis of a large amount of samples. Then, the authors suggest that this quick method could be useful for measuring mercury in human hair. Therefore, the mercury content in hair for a non-exposed group of children (n=40) living in Spain was evaluated. The mean and median hair mercury levels for the subjects under study were found to be lower than the value of 1 microg/g, corresponding to the reference dose of 0.1 microg of methylmercury per kilogram body weight set by the U.S. Environmental Protection Agency.     

Brain and tissue levels of mercury after chronic methylmercury exposure in the monkey

Estimated half-lives of mercury following methylmercury exposure in humans are 52-93 d for whole body and 49-164 d for blood. In its most recent 1980 review, the World Health Organization concluded that there was no evidence to suggest that brain half-life differed from whole-body half-life. In the present study, female monkeys (Macaca fascicularis) were dosed for at least 1.7 yr with 10, 25, or 50 micrograms/kg.d of mercury as methylmercuric chloride. Dosing was discontinued, and blood half-life was determined to be about 14 d. Approximately 230 d after cessation of dosing, monkeys were sacrificed and organ and regional brain total mercury levels determined. One monkey that died while still being dosed had brain mercury levels three times higher than levels in blood. Theoretical calculations were performed assuming steady-state brain:blood ratios of 3, 5, or 10. Brain mercury levels were at least three orders of magnitude higher than those predicted by assuming the half-life in brain to be the same as that in blood. Estimated half-lives in brain were between 56 (brain:blood ratio of 3) and 38 (brain:blood ratio of 10) d. In addition, there was a dose-dependent difference in half-lives for some brain regions. These data clearly indicate that brain half-life is considerably longer than blood half-life in the monkey under conditions of chronic dosing.     

Protein binding of mercury in milk and plasma from mice and man--a comparison between methylmercury and inorganic mercury.

Inorganic mercury has previously been shown to be excreted to milk from plasma to a higher extent than methylmercury. Protein binding of mercury as methylmercury and inorganic mercury in whey and plasma from mouse and man was studied in order to get a better understanding of the transport of mercury into milk. Mice were administered a single i.v. dose of 0.25 mg Hg/kg body weight labelled with (CH3)203HgCl or 203HgCl2, resulting in 11 ng Hg/g milk and 38 ng Hg/g milk after 1 h, respectively. Milk and plasma from mice and man were also incubated with the respective radiolabelled compound (150 ng Hg/g milk or plasma). Casein, fat and whey fractions in milk from methylmercury treated mice were found to contain 11, 39 and 34%, respectively, and from inorganic mercury treated mice 31, 15 and 41%, respectively, of the total amount of mercury in milk. Serum albumin was a major mercury binding protein in whey and plasma from mice for both methylmercury and inorganic mercury, as demonstrated by FPLC gel filtration and anion-exchange chromatography and further characterised by SDS-PAGE for whey. In addition, anion-exchange chromatography indicated that inorganic mercury, but not methylmercury, in whey from mouse milk formed a dimer of serum albumin. The unbound fraction of mercury in whey and plasma from mice was very small (<0.7%), and somewhat higher in plasma and whey from man. It is concluded, that the unbound fraction in plasma cannot be a determining factor for the observed differences in milk excretion between the two mercury compounds. Instead, it is suggested that methylmercury and to some extent inorganic mercury are transferred from plasma into milk using albumin as a passive carrier.     

A comparison of the lactational and transplacental deposition of mercury in offspring from methylmercury-exposed mice. Effect of seleno-L-methionine

Females exposed to methylmercury expose their offspring to mercury across the placenta as well as through milk. The relative importance of these two routes of exposure has hitherto been unresolved. Using a cross-fostering model with female mice, the transplacental and lactational exposures to mercury were evaluated separately. In female mice exposed to low, non-toxic levels of methylmercury in the drinking water the deposition of mercury in offspring before birth was quantitatively more important than later transfer of mercury from milk to offspring. Seleno-l-methionine supplementation of the dams increased the whole-body deposition in offspring. As methylmercury is anticipated to be absorbed completely and the young mice are unable to excrete mercury, these data indicate that seleno-l-methionine affects the kinetics of the inorganic mercury pool, which, due to demethylating processes, is present in both blood and milk of methylmercury-exposed females.     

Prevalence of new psychoactive substances: A retrospective study in hair

New psychoactive substances are conquering the drug scene. Police seize different colourful packages with exceptional names. They are declared as ‘bath salts’, ‘plant food’, or ‘research chemical powders’. Little is known about the actual prevalence of these drugs. Reanalysis of hair samples from routine cases concerning the presence of new psychoactive substances or ‘smart drugs’ should provide insight into changing patterns of designer drugs. All hair samples from 2009 and 2010 that originally tested positive for amphetamines or MDMA (N = 325) were reanalyzed for new or smart drugs such as 4‐fluoroamphetamine, piperazines (BZP, mCPP and TFMPP), cathinones (4‐MMC (mephedrone), methylone, butylone, ethylone, MDPV, methcathinone and cathinone), methylphenidate and ketamine. Hair snippets were extracted using a two‐step extraction procedure. The analytes were analyzed using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) (electrospray ionization; multiple‐reaction‐monitoring mode – information dependent acquisition – enhanced product ion scan). New psychoactive substances were found in 120 cases (37%). Concerning the piperazine drugs, mCPP was positive in 34 (10.5%) cases and TFMPP in one case. Five mCPP cases were also positive for trazodone, an antidepressant which is metabolized to mCPP. In 11 (3%) cases, 4‐MMC was detected. Concerning the smart drugs, methylphenidate was found in 16 (5%). Ketamine was found in 45 (14%) cases. 4‐Fluoroamphetamine was identified in 12 (4%) cases and methylone in one case.In conclusion, there is a high prevalence of these drugs. Consequently, at least the most common ones (e.g. mCPP, KET, 4‐MMC and 4‐FA) should be included in screening procedures in clinical and forensic toxicology. Copyright © 2012 John Wiley & Sons, Ltd.     

A comparison of the effects of buspirone and diazepam on plasma corticosterone levels in rat

The effect of the anxiolytic agents, buspirone and diazepam, on the hypothalamic-pituitary-adrenal axis (HPAA), indicated by changes in the concentration of corticosterone (CS) in plasma, were studied 1/2, 1, 2, 4, 6, 8 and 24 hr after administration of the drug (i.p.). Samples of plasma were collected in the mid-morning (0930-1130 hr) when activity in the hypothalamic-pituitary-adrenal axis in the rat and control levels of corticosterone were low and were repeated in the afternoon (1400-1600 hr) when activity in the hypothalamic-pituitary-arenal axis and levels of corticosterone were higher. At small doses (1 mg/kg) buspirone had a greater facilitating effect on the hypothalamic-pituitary-adrenal axis than did diazepam. In addition, buspirone had a greater maximum facilitatory effect (477%) on levels of corticosterone than diazepam (345%). However, buspirone (ED50 = 8.6 mumol/kg) and diazepam (ED50 = 8.7 mumol/kg) were equipotent. Administration of 1 mg/kg of buspirone in the morning increased the combined 1/2 and 1 hr circulating levels of corticosterone 75% above control levels. Diazepam, at 1 mg/kg, did not produce any significant changes in levels of corticosterone. Large doses (10 mg/kg) of buspirone increased morning levels of corticosterone by 328% and diazepam increased levels of corticosterone by 265%. During the afternoon small doses of buspirone or diazepam did not significantly alter levels of corticosterone.(ABSTRACT TRUNCATED AT 250 WORDS)