Long-Term Stability of Inorganic, Methyl and Ethyl Mercury in Whole Blood: Effects of Storage Temperature and Time.

In this study, we evaluated the effect of temperature on the long-term stability of three mercury species in bovine blood. We used inductively coupled plasma mass spectrometry (ICP-MS) analysis to determine the concentrations of inorganic (iHg), methyl (MeHg) and ethyl (EtHg) mercury species in two blood pools stored at temperatures of -70, -20, 4, 23°C (room temperature) and 37°C. Over the course of a year, we analyzed aliquots of pooled specimens at time intervals of 1, 2, 4 and 6 weeks and 2, 4, 6, 8, 10 and 12 months. We applied a fixed-effects linear model, step-down pairwise comparison and coefficient of variation statistical analysis to examine the temperature and time effects on changes in mercury species concentrations. We observed several instances of statistically significant differences in mercury species concentrations between different temperatures and time points; however, with considerations of experimental factors (such as instrumental drift and sample preparation procedures), not all differences were scientifically important. We concluded that iHg, MeHg and EtHg species in bovine whole blood were stable at -70, -20, 4 and 23°C for 1 year, but blood samples stored at 37°C were stable for no more than 2 weeks.

Selective determination method for measurement of methylmercury and ethylmercury in soil/sediment samples using high-performance liquid chromatography-chemiluminescence detection coupled with simple extraction technique.

A method for the simultaneous determination of monomethylmercury (MeHg(+)) and monoethylmercury (EtHg(+)) in soil/sediment samples was developed. The method involves eluting mercury species from the soil/sediment samples using 5M HCl containing 5mM Pd(2+) and 0.1M Cu(2+) and then extracting MeHg(+) and EtHg(+) into toluene as chlorides. These alkylmercury chlorides are then back-extracted into an aqueous EDTA solution, creating EDTA complexes. Finally, an emetine-dithiocarbamate (emetineCS2) solution is added to the EDTA solution to form emetineCS2-alkylmercury complexes. EmetineCS2-MeHg and emetineCS2-EtHg were separated using reverse-phase HPLC and then detected by the chemiluminescence reaction with tris(2,2'-bipyridine)ruthenium(III). The MeHg(+) and EtHg(+) calibration curves, using the peak height, were linear from 0.5 to 20ng (as Hg). The detection limit was 0.16ng/g (analyzing 1g soil or sediment). The procedure was validated by analyzing a certified reference material (ERM CC580, estuarine sediment). The MeHg(+) concentration determined using the proposed method was in good agreement with the certified value, and EtHg(+) was detected in the reference material. A preliminary study of the relationship between environmental mercury concentrations and MeHg(+) production was performed.

[Lack of association between thimerosal-containing vaccines and autism]. / Brak zwiazku miedzy ekspozycja na szczepionki zawierajace tiomersal i rozwojem autyzmu u dzieci.

In Poland, administered childhood vaccines still contain thimerosal as a preservative. Despite the access to mercury free formulas, the most of children are still vaccinated by thimerosal-containing vaccines (TCV) owing to economical reasons. That circumstances caused the rising discussion on potential harmful influence of TCVs on children health. The objective of this analysis was to determine an association of TCVs exposure with the risk of autism. Study population included 96 cases diagnosed with childhood or atypical autism and 192 controls matched individually by year of birth, gender, and physician's practice. Data on autism diagnose and vaccination history were from GPs. Data on the other possible autism risk factors were collected from mothers. Conditional logistic regression was used to assess the risk of autism due to TCVs exposure. No significant association was found between TCVs exposure and autism. After adjusting to potential confounders, odds ratios of the risk of autism developing for infants vaccinated with TCVs were 1.52 (95% CI: 0.29-11.11) for doses 12.5-87.5 microg, 2.78 (95% CI: 0.29-11.11) for 100-137.5 microg and 1.97 (95% CI: 0.37-18.95) for these exposed > or = 150 microg. Our study revealed no evidence of an association between TCVs and autism.

Solution cathode glow discharge induced vapor generation of mercury and its application to mercury speciation by high performance liquid chromatography-atomic fluorescence spectrometry.

A novel solution cathode glow discharge (SCGD) induced vapor generation was developed as interface to on-line couple high-performance liquid chromatography (HPLC) with atomic fluorescence spectrometry (AFS) for the speciation of inorganic mercury (Hg(2+)), methyl-mercury (MeHg) and ethyl-mercury (EtHg). The decomposition of organic mercury species and the reduction of Hg(2+) could be completed in one step with this proposed SCGD induced vapor generation system. The vapor generation is extremely rapid and therefore is easy to couple with flow injection (FI) and HPLC. Compared with the conventional HPLC-CV-AFS hyphenated systems, the proposed HPLC-SCGD-AFS system is very simple in operation and eliminates auxiliary redox reagents. Parameters influencing mercury determination were optimized, such as concentration of formic acid, discharge current and argon flow rate. The method detection limits for HPLC-SCGD-AFS system were 0.67 µg L(-1) for Hg(2+), 0.55 µg L(-1) for MeHg and 1.19 µg L(-1) for EtHg, respectively. The developed method was validated by determination of certified reference material (GBW 10029, tuna fish) and was further applied for the determination of mercury in biological samples.

Isotopic fractionation of mercury induced by reduction and ethylation.

Isotope ratio measurements characterizing (202)Hg/(200)Hg in NIST SRM 3133 Mercury Standard Solution were undertaken by multicollector inductively coupled plasma mass spectrometry employing NIST SRM 997 Tl for mass bias correction by use of the slope and the intercept obtained from a natural logarithmic plot of each session of measurements of (202)Hg/(200)Hg against (205)Tl/(203)Tl. The calculated value of 1.285333 +/- 0.000192 (mean and one standard deviation, n = 40) for the mass bias corrected (202)Hg/(200)Hg was then used for mass bias correction of other Hg isotope pairs. Ratios of 0.015337 +/- 0.000011, 1.68770 +/- 0.00054, 2.3056 +/- 0.0015, 1.3129 +/- 0.0013, 2.9634 +/- 0.0038, and 0.67937 +/- 0.0013 (expanded uncertainty, k = 2) were obtained for (196)Hg/(198)Hg, (199)Hg/(198)Hg, (200)Hg/(198)Hg, (201)Hg/(198)Hg, (202)Hg/(198)Hg, and (204)Hg/(198)Hg, respectively. Reduction of Hg(II) to Hg(0) in solutions of SRM 3133 was then undertaken using SnCl(2), NaBH(4), UV photolysis in the presence of formic acid, and ethylation of Hg(II) using NaBEt(4.) These reactions induced significant isotope fractionation with maximum values of 1.17 +/- 0.07, 1.08 +/- 0.09, 1.34 +/- 0.07, and 3.59 +/- 0.09 per thousand (one standard deviation, 1SD, n = 5) for delta (202/198)Hg relative to the initial isotopic composition in the solution following 85-90% reduction of the Hg by SnCl(2), NaBH(4), UV photolysis, and ethylation with NaBEt(4), respectively. Mass-dependent fractionation was found to be dominant for all reduction processes.

Zinc(II), cadmium(II), mercury(II), and ethylmercury(II) complexes of phosphinothiol ligands.

Neutral zinc, cadmium, mercury(II), and ethylmercury(II) complexes of a series of phosphinothiol ligands, PhnP(C6H3(SH-2)(R-3))3-n (n = 1, 2; R = H, SiMe3) have been synthesized and characterized by IR and NMR ((1)H, (13)C, and (31)P) spectroscopy, FAB mass spectrometry, and X-ray structural analysis. The compounds [Zn{PhP(C6H4S-2)2}] (1) and [Cd{Ph2PC6H4S-2}2] (2) have been synthesized by electrochemical oxidation of anodic metal (zinc or cadmium) in an acetonitrile solution of the appropriate ligand. The presence of pyridine in the electrolytic cell affords the mixed complexes [Zn{PhP(C6H4S-2)2}(py)] (3) and [Cd{PhP(C6H4S-2)2}(py)] (4). [Hg{Ph2PC6H4S-2}2] (5) and [Hg{Ph2PC6H3(S-2)(SiMe3-3)}2] (6) were obtained by the addition of the appropriate ligand to a solution of mercury(II) acetate in methanol in the presence of triethylamine. [EtHg{Ph2PC6H4S-2}] (7), [EtHg{Ph2P(O)C6H3(S-2)(SiMe3-3)}] (8), [{EtHg}2{PhP(C6H4S-2)2}] (9), and [{EtHg}2{PhP(C6H3(S-2)(SiMe3-3))2}] (10) were obtained by reaction of ethylmercury(II) chloride with the corresponding ligand in methanol. In addition, in the reactions of EtHgCl with Ph2PC6H4SH-2 and with the potentially tridentate ligand PhP(C6H3(SH-2)(SiMe3-3)) 2, cleavage of the Hg-C bond was observed with the formation of [Hg{Ph2PC6H4S-2}2] (5) and [Hg(EtHg) 2{PhP(O)(C6H3(S-2)(SiMe3-3))2}2] (11), respectively, and the corresponding hydrocarbon. The crystal structures of [Zn3{PhP(C6H4S-2)2}2{PhP(O)(C6H4S-2)2}] (1*), [Cd2{Ph2PC6H4S-2}3{Ph2P(O)C6H4S-2}] (2*), 3, 5, 6, [EtHg{Ph2P(O)C6H4S-2}] (7*), 8, 9, [{EtHg}2{PhP(O)(C6H3(S-2)(SiMe3-3))2}] (10*), and 11 are discussed. The molecular structures of 1, 2, 4, 7, and 10 have also been studied by means of density functional theory (DFT) calculations.

Exposure to mercury during the first six months via human milk and vaccines: modifying risk factors.

Breastfeeding is the best natural protection infants have against morbidity and mortality, and the development of safe and effective vaccines has made it possible to immunize children against infectious disease. Both of these mechanisms for ensuring good health in children may be compromised by contact with mercury (Hg). Maternal exposure to environmental Hg during pregnancy can predispose nursing children to neurodevelopmental disorders. Despite the World Health Organization assurance that thimerosal-preserved vaccines are safe to use in infants, the United States, the European Union, and dozens of other countries have eliminated thimerosal as a vaccine preservative and stopped the immunization of children with such vaccines. Because of the increase in environmental pollution and the need to produce cheap and safe vaccines, there is a need to address the uncertainty of vaccine-ethylmercury risk of toxicity and Hg exposure during breastfeeding.

Simultaneous determination of trace levels of ethylmercury and methylmercury in biological samples and vaccines using sodium tetra(n-propyl)borate as derivatizing agent.

Because of increasing awareness of the potential neurotoxicity of even low levels of organomercury compounds, analytical techniques are required for determination of low concentrations of ethylmercury (EtHg) and methylmercury (MeHg) in biological samples. An accurate and sensitive method has been developed for simultaneous determination of methylmercury and ethylmercury in vaccines and biological samples. MeHg and EtHg were isolated by acid leaching (H2SO4-KBr-CuSO4), extraction of MeHg and EtHg bromides into an organic solvent (CH2Cl2), then back-extraction into Milli-Q water. MeHg and EtHg bromides were derivatized with sodium tetrapropylborate (NaBPr4), collected at room temperature on Tenax, separated by isothermal gas chromatography (GC), pyrolysed, and detected by cold-vapour atomic fluorescence spectrometry (CV AFS). The repeatability of results from the method was approximately 5-10% for EtHg and 5-15% for MeHg. Detection limits achieved were 0.01 ng g-1 for EtHg and MeHg in blood, saliva, and vaccines and 5 ng g-1 for EtHg and MeHg in hair. The method presented has been shown to be suitable for determination of background levels of these contaminants in biological samples and can be used in studies related to the health effects of mercury and its species in man. This work illustrates the possibility of using hair and blood as potential biomarkers of exposure to thiomersal.

Route of decomposition of thiomersal (thimerosal).

The route of formation and identification of the principal degradation products of thimerosal (thiomersal) has been undertaken. The initial oxidation to dithiosalicylic acid is followed by cleavage of the disulphide bond of the dithiosalicylic acid by the ethylmercuric ion to reform 1.5 mol of thimerosal with concurrent oxidation to form 0.5 mol of 2-sulfinobenzoic acid for each mole of dithiosalicylic acid. In the presence of copper ions 2-sulfobenzoic acid was also formed. A mechanism has been proposed which accounts for the stoichiometry of the cleavage reaction observed and the significance of the reaction is discussed.

Crystallization of retinol dehydratase from Spodoptera frugiperda: improvement of crystal quality by modification by ethylmercurythiosalicylate.

Retinol dehydratase is a sulfotransferase which is presumed to catalyze the dehydration of its substrate via a transient retinyl sulfate intermediate. Crystals (space group P2(1), unit-cell parameters a = 82.05, b = 66.61, c = 84.90 A, beta = 111.29 degrees ) are significantly improved by covalent modification of the protein with ethylmercury.

Degradation of methyl and ethyl mercury by singlet oxygen generated from sea water exposed to sunlight or ultraviolet light.

Photodegradation of methyl mercury (MeHg) and ethyl Hg (EtHg) in sea water was studied by sunlight or ultraviolet (UV) light exposure, and by determining inorganic Hg produced by degradation. Sea water containing 1 microM MeHg or EtHg was exposed to sunlight or UV light. N-Acetyl-L-cysteine was added to the solution for preventing Hg loss during the light exposure. MeHg and EtHg in sea water were degraded by sunlight (> 280 nm), UV light A (320-400 nm) and UV light B (280-320 nm), though the amounts of inorganic Hg produced from MeHg were 1/6th to 1/12th those from EtHg. Inorganic Hg production was greater with increasing concentration of sea water. Degradation of MeHg and EtHg by the UV light A exposure was inhibited by singlet oxygen (1O2) trappers such as NaN3, 1,4-diazabicyclo[2,2,2]octane, histidine, methionine and 2,5-dimethylfuran. On the other hand, inhibitors or scavengers of superoxide anion, hydrogen peroxide or hydroxyl radical did not inhibit the photodegradation of alkyl Hg. These results suggested that 1O2 generated from sea water exposed to sunlight, UV light A or UV light B was the reactive oxygen species mainly responsible for the degradation of MeHg and EtHg.