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PubMed1979

Individual mercury exposure of chloralkali workers and its relation to blood and urinary mercury levels.

On two occasions, chloralkali workers were investigated with regard to personal air mercury exposure, blood mercury and urinary mercury. The first investigation (13 workers, 2 weeks) was made at an exposure above the threshold limit value (64 microgram/m3, range 36--112), the second (16 workers, 8 weeks) at a lower exposure (23 microgram/m3, range 15--43). At the higher level of exposure, good correlations were found between air exposure and blood or urinary mercury for the group, but not for individuals. At the lower level, the correlations were less pronounced for the group. For individuals, the best correlation was found between mean air exposure during one week and blood mercury about half a week later. Other individuals, mainly the least exposed, showed no such correlation. Corresponding correlations were not found for urinary mercury. The urinary excretion rate was determined only for the last few hours of the workday, but the results agree with earlier investigations of 24-h excretion on a group basis. The threshold limit value for mercury in air (50 microgram/m3) corresponds to 150--175 nmol Hg/1 blood (= 30--35 microgram/1) for the group, with large individual variation.

Adult↗

PubMed1976

[Radiochemical investigations on the decomposition of (mono) methyl-mercury by means of acid with regard to the determination of total mercury in fish (author's transl)].

Considerable amonts of mercury in fish muscle tissue are organically bound i.e. appear as (mono)methylmercury-compounds. In order to make mercury of organic origin available for the determination of total mercury by the "cold vapour atomic absorption method", a splitting of the carbon-mercury bond by means of suitable chemical treatment must be maintained beforehand. The main subject of this article are investigations with special regard to the behaviour of (mono)methylmercurychloride during different wet digestion methods. The procedures under study involve wet digestion under reflux with HNO3, with mixtures of HNO3 and HC10(4) and HNO3 and H2SO4, as well as wet digestion with HNO3 in a closed system (pressure decomposition). The course of the decomposition of (mono)methylmercury dependent on time, temperature and concentration of reagents are discussed in detail. All experiments were controlled by measurement of the radioactivity of Hg-203 which had been added in the chemical form of CH3-Hg-Cl. From the analytical results obtained two methods of sample preparation have been derived that permit a reliable determination of total mercury in fish.

Fish Products↗

PubMed1976

Purification and properties of an enzyme catalyzing the splitting of carbon-mercury linkages from mercury-resistant Pseudomonas K-62 strain. I. Splitting enzyme 1.

An enzyme (S-1) which catalyzes the splitting of carbon-mercury linkages of organomercury compounds was purified about 24-fold from the cell-free extract of mercury-resistant Pseudomonas K-62 strain by treatment with streptomycin, precipitation with ammonium sulfate, and successive chromatography on Sephadex G-150, DEAE-Sephadex, and DEAE-cellulose. A purified preparation of the enzyme showed a single band on polyacrylamide gel electrophoresis, and was colorless. The molecular weight of the enzyme was estimated to be 19,000, and Km was 5.3 X 10(-5) M for p-chloromercuribenzoic acid (PCMB). The temperature and pH optimum for the reaction were 50degrees and 7.0, respectively. The enzyme was capable of catalyzing the decomposition of methylmercuric chloride (MMC), ethylmercuric chloride (EMC), phenylmercuric acetate (PMA), and PCMB in the presence of a sulfhydryl compound to form a mercuric ion plus methane, ethane, benzene, or benzoic acid, respectively. The mercuric ion thus formed was reduced to metallic mercury by metallic mercury-releasing enzyme (MMR-enzyme).

Chloromercuribenzoates↗

PubMed1978

The influence of selenium on the level of mercury and metallothionein in rat kidneys in prolonged exposure to different mercury compounds.

Mercuric chloride, phenylmercuric chloride, ethylmercuric chloride /0,23 mg Hg/kg/ and methylmercurycyan guanidine /0,46 mg Hg/kg/ were orally administered to rats every second day for 14 weeks. The same doses of the above mentioned mercury compounds were administered alternately with sodium selenite /0,18 mg Se/kg/ to parallel groups of rats at the same time. The level of total and inorganic mercury and of metallothionein was determined. All mercury compounds increased the level of metallothionein in rat kidneys. In rats which received only selenium the level of metallothionein was twice lower in the kidneys in relation to the physiological level of this protein. Selenium eliminated the stimulation of biosynthesis of metallothionein by mercury.

Animals↗

PubMed1977

Organ mercury levels in infants with omphaloceles treated with organic mercurial antiseptic.

Samples of fresh and fixed tissues from infants with exomphalos treated by thiomersal application were analysed for mercury content. The results showed that thiomersal can induce blood and organ levels of organic mercury which are well in excess of the minimum toxic level in adults and fetuses. The analysis of fresh and fixed tissues must be carefully controlled against normal tissues in order to interpret mercury levels accurately.

Brain↗

PubMed1978

Purification and properties of a second enzyme catalyzing the splitting of carbon-mercury linkages from mercury-resistant Pseudomonas K-62.

An enzyme (splitting enzyme 2) which catalyzes the splitting of carbon-mercury linkage of arylmercury compounds was found in extracts of mercury-resistant Pseudomonas K-62. This enzyme was purified about 725-fold by treatment with streptomycin, precipitation with ammonium sulfate, and successive chromatography on Sephadex G-75 and diethylaminoethyl-cellulose. A purified preparation of the enzyme showed a single band in electrophoresis either on polyacrylamide or sodium dodecyl sulfate-containing polyacrylamide gels. The molecular weight of the enzyme was estimated to be 20,000 (determined by Sephadex G-75 gel filtration) 17,000 (determined by sodium dodecyl sulfate-polyacrylamide disc gel electrophoresis). The enzyme showed a Km of 180 micron and a Vmax of 3.1 mumol/min per mg for p-chloromercuribenzoic acid and a Km of 250 micron and a Vmax of 20 mumol/min per mg for phenylmercuric acetate. The optimum temperature and pH for the reaction were 40 degrees C and 5.0, respectively.

Chloromercuribenzoates↗

PubMed1979

Rapid separation on copper powder of total mercury in blood and determination of mercury by flameless atomic absorption spectrometry.

The determination of mercury in blood by flameless atomic absorption spectrometry (FAAS) has been described. Prior to its analysis, the sample was decomposed by combustion and separated on a copper powder micro-column. A special type of cell has been used which gives a better sensitivity compared with the types of cells described in the literature and the method of FAAS analysis has been improved. The sensitivity of 0.1 ng for 1% absorbance was observed and the standard deviation for six determinations at this level was found to be +/- 0.05 ng, for 95% probability.

Copper↗

PubMed1979