Species-specific isotope dilution with permeation tubes for determination of gaseous mercury species.

Instrumentation and methodology for determination of the gaseous mercury species Hg0, (CH3)2Hg, and CH3Hg+ has been developed. The method is based on continuous addition of gaseous isotopically enriched Hg species (tracers) at the point of sample acquisition, in combination with reduced pressure sampling on Carbotrap adsorbent tubes. Permeation tubes are used for generation of the tracers. Collected species are thermally desorbed and purged through an aqueous sodium tetraethylborate solution for derivatization of CH3Hg+. The purged gas is dried with a Nafion membrane, and the Hg species are subsequently collected on a smaller Tenax TA adsorbent tube. Species are then thermally desorbed from the Tenax TA and introduced into a gas chromatograph connected to an inductively coupled plasma mass spectrometer for separation and detection. To be able to add tracers during field sampling, we developed a portable device, supplying the permeation tubes with a thermostated and mass flow-controlled air stream of 5.0 +/- 0.1 degrees C and 50.0 mL min(-1), respectively. Typical permeation rates obtained during a period of more than 6 weeks were 12.93 +/- 0.56, 0.42 +/- 0.01, and 0.49 +/- 0.03 (mean +/- standard deviation) pg of Hg min(-1) for a set of 199Hg0, (CH3)2 198Hg, and CH3 200Hg+ tubes, respectively. Methodological detection limits (3sigma) were determined to 700 pg of Hg m(-3) for Hg0 and 50 pg of Hg m(-3) for (CH3)2Hg and CH3Hg+. The collection efficiencies for sampled volumes of 400 L of synthetic air on the Carbotrap tubes used in this study were 13 +/- 2, 102 +/- 2, and 99 +/- 4% for Hg0, (CH3)2Hg, and CH3Hg+, respectively. Desorption efficiencies for the above species and tubes were 98 +/- 2, 98 +/- 1, and 90 +/- 4%, respectively. Fractions (20-40%) of the added (CH3)2 198Hg and CH3 200Hg+ tracers were found to be transformed during the analytical processing of collected air samples. Determined concentrations in the research laboratory air, corrected for species transformations, were 3-53, 8-11, and 1-2 ng of Hg m(-3) for Hg0, (CH3)2Hg, and CH3Hg+, respectively. Concentrations in the ambient air were determined to be 2.1-2.6 ng m(-3) for Hg0 and below the detection limit for (CH3)2Hg and CH3Hg+.

Effects on the nervous system in different groups of workers exposed to aluminium.

OBJECTIVE: To investigate possible neurotoxic effects in groups of aluminium pot room and foundry workers, aluminium welders, and a small group of workers exposed to aluminium in the production of flake powder. METHODS: Exposure to aluminium was evaluated with aluminium concentrations in blood and urine as well as a questionnaire. The groups exposed to aluminium were compared with a group of mild steel welders. Neurotoxic effects were studied with mood and symptom questionnaires and several psychological and neurophysiological tests. RESULTS: The pot room and foundry workers showed very low aluminium uptake as their aluminium concentrations in blood and urine were close to normal, and no effects on the nervous system were detected. The group of workers exposed to flake powder had high concentrations of aluminium in blood and urine, even higher than those of the aluminium welders. However, aluminium could not be shown to affect the functioning of the nervous system in flake powder producers. Although significant effects could not be shown in the present analysis of the data on welders, the performance of the welders exposed to high concentrations of aluminium was affected according to the analyses in the original paper from this group. CONCLUSIONS: For the pot room and foundry workers no effects related to the exposure to aluminium could be found. For the group of flake powder producers exposed for a short term no effects on the nervous systems were evident despite high levels of exposure. Due to the high concentrations of aluminium in the biological samples of this group, measures to reduce the exposure to aluminium are recommended, as effects on the central nervous system might develop after protracted exposures. However, this assumption needs to be verified in further studies.

Efficiency of solvent extraction methods for the determination of methyl mercury in forest soils.

Methyl mercury was determined by gas chromatography, microwave induced plasma, atomic emission spectrometry (GC-MIP-AES) using two different methods. One was based on extraction of mercury species into toluene, pre-concentration by evaporation and butylation of methyl mercury with a Grignard reagent followed by determination. With the other, methyl mercury was extracted into dichloromethane and back extracted into water followed by in situ ethylation, collection of ethylated mercury species on Tenax and determination. The accuracy of the entire procedure based on butylation was validated for the individual steps involved in the method. Methyl mercury added to various types of soil samples showed an overall average recovery of 87.5%. Reduced recovery was only caused by losses of methyl mercury during extraction into toluene and during pre-concentration by evaporation. The extraction of methyl mercury added to the soil was therefore quantitative. Since it is not possible to directly determine the extraction efficiency of incipient methyl mercury, the extraction efficiency of total mercury with an acidified solution containing CuSO4 and KBr was compared with high-pressure microwave acid digestion. The solvent extraction efficiency was 93%. For the IAEA 356 sediment certified reference material, mercury was less efficiently extracted and determined methyl mercury concentrations were below the certified value. Incomplete extraction could be explained by the presence of a large part of inorganic sulfides, as determined by x-ray absorption near-edge structure spectroscopy (XANES). Analyses of sediment reference material CRM 580 gave results in agreement with the certified value. The butylation method gave a detection limit for methyl mercury of 0.1 ng g(-1), calculated as three times the standard deviation for repeated analysis of soil samples. Lower values were obtained with the ethylation method. The precision, expressed as RSD for concentrations 20 times above the detection limit, was typically 5%.

Fixation and metal release from the Tifit femoral stem prosthesis. 5-year follow-up of 64 cases.

We stratified the fixation of the femoral component in 64 hips with degenerative joint disease into 3 groups, cemented (C), proximal hydroxyapatite coating (HA) or proximal porous coating (P). All implants had the same basic design and were made of TiAIV alloy. The migration of the implants was assessed by radiostereometry. After 5 years, the mean subsidences in the cemented and porous-coated groups were 0.16 and 0.31 mm, whereas the HA-coated implants displayed a mean proximal migration of 0.1 mm. 7 stems (2 C, 1 HA, 4 P) showed a continuous subsidence (> 0.25 mm) between the 2- and 5-year follow-up. 1 porous-coated stem was revised after the 2-year follow-up, because of pain and implant failure (previously reported) and 1 cemented stem was revised after 5 years because of pain and osteolysis. In a subset of patients, all with a femoral head made of aluminum oxide, the levels of metal were determined using atomic adsorption spectrometry. Subsidence of the stem between the 2- and 5-year follow-up was associated with increased levels of aluminum in the blood at 2 years. Generation of metallic particles from abrasive wear of the stem followed by third body abrasion of the ceramic femoral head could be one explanation of this finding. 5 hips which had shown high levels of titanium and aluminum in joint fluid at the 2-year follow-up displayed increased subsidence and developed proximal radiolucencies or osteolysis at the 5-year follow up. One of these was the cemented hip which was subsequently revised.

Is placenta a good indicator of cadmium and lead exposure?

Distribution of lead and cadmium was studied in 25 placentas. Samples were taken from 6 different lobuli, and lead and cadmium concentrations were not determined by graphite furnace atomic absorption spectrometry. Lead and cadmium were not distributed uniformly, and the concentrations differed by a factor > or = 2 among different lobuli within the same placenta in 36% and 52% of the placentas, respectively. Placental lead and cadmium concentrations were also determined in homogenized samples from smelter (n = 49) and control (n = 53) areas in northern Sweden. Mean lead and cadmium concentrations were low, even in the smelter area (geometric means = 10 ng/g and 3 ng/g wet weight, respectively). The significant differences observed (i.e., higher blood lead concentrations in the smelter area during pregnancy and in umbilical cord blood) were not reflected in the placenta. We concluded, therefore, that the placenta is not a suitable organ to use for the monitoring of environmental exposure to lead. It could be used to monitor cadmium exposure, but if pregnancy outcome is to be studied, consideration should be given to the sampling procedure.

Recent developments in atomizers for electrothermal atomic absorption spectrometry.

This review first describes general requirements to be met for suitable base materials used to produce electrothermal atomizers (ETAs). In this connection the physical and chemical properties of adequate types of graphite and metals are discussed. Further, various atomizer designs, their temperature dynamics during atomization and general performance characteristics are critically reviewed. For end-heated Massmann-type atomizers, discussions are focused on recent developments of, e.g., contoured tubes to achieve improved temperature homogeneity over the tube length, second surface atomizers to realize temporally isothermal atomization and tubes with graphite filters to reduce interference effects. The state-of-the-art of platform equipped, side-heated atomizers with integrated contacting bridges are characterized mainly with respect to heating dynamics, as well as susceptibility to interference- and memory effects. In contrast to end-heated ETAs, the tube ends of side-heated ETAs are freely located in the furnace compartment and, as a consequence of this configuration, convective gas flows can easily appear. The magnitude and effect of these flows on analytical performance are discussed and measures are suggested, permitting operation under diffusion controlled conditions. A critical comparison of classical constant temperature atomizers with state-of-the-art platform equipped ETAs is made and from this it is concluded that future ETA developments are likely to involve only minor modifications aiming at, e.g., the reduction of cycling times or the improvement of tube surface properties.

Aluminium accumulation in some tissues of rats with compromised kidney function induced by cadmium-metallothionein.

Two experiments (I and II) were performed to study aluminium accumulation in brain as well as in several other tissues in male Wistar rats. A single intraperitoneal injection of cadmium-metallothionein (CdMT, 0.1-0.4 mg Cd/kg b.wt.) was used to compromise kidney function 12 hr before the final aluminium injection in both experiments. In experiment I, rats were maintained on diets deficient (0.01%, w/w) in calcium (-Ca) or providing adequate (+Ca) dietary calcium (0.9%) for 6 weeks. Among animals given a daily intraperitoneal dose of aluminium chloride (10.8 mg Al/kg per day) on 6 consecutive days there was a tendency towards higher aluminium level in brains of rats with compromised kidney function from CdMT (in -Ca rats: the geometric mean [G] = 288 versus 205 ng/g wet weight [w., wt.], P = 0.07, and in +Ca rats: G = 242 versus 164, P < 0.05) as compared to animals given no CdMT. The results from experiment II (all rats were given aluminium 5.6 mg Al/kg 2 and 12 hr after CdMT injection) demonstrated a higher level of aluminium (G: 41 ng/g w. wt., P < 0.05) in brains of rats with only slightly damaged kidney function (0.1 mg Cd/kg) than in those given no CdMT (G: 29 ng/g w. wt.). It was also observed that 1) calcium deficiency had a statistically significant effect (P < 0.05) in increasing kidney retention of intraperitoneal aluminium (G: 327 micrograms/g w. wt.) as compared to rats with a normal calcium supply in the diet (G: 54 micrograms/g w. wt.); 2) when aluminium concentration in kidney was at and above 54 micrograms/g wet tissue, kidney damage was observed. The above results indicate that compromised kidney function including tubular damage induced by a low-dose of CdMT may play a crucial role in the accumulation of aluminium in brain and other tissues. Since tubular function decreases with age in human populations, these findings in rats may be of considerable importance if a similar phenomenon would occur in humans. Therefore, the possibility of increased aluminium retention in persons with low calcium and high aluminium intakes may need to be further investigated.

A follow-up study of five cases of aluminosis.

Five men were investigated after having pulmonary aluminosis due to exposure to aluminium pyrotechnic flake powder during the late 1940s. Two of the men had died 6 years and 20 years after exposure respectively, due to their lung disease. One man had died from heart failure 34 years after the end of exposure. Today, more than 40 years after exposure, two men were available for investigation. They had no respiratory symptoms and their vital lung capacities had not deteriorated during these years. One of the two survivors had developed a dementia with motor disturbances, which is not consistent with Alzheimer's dementia. This man had a very high concentration of aluminium in his cerebrospinal fluid. The other survivor had a normal concentration and was not demented.

Effects on the nervous system among welders exposed to aluminium and manganese.

OBJECTIVES: The purpose was to study the effects on the nervous system in welders exposed to aluminium and manganese. METHODS: The investigation included questionnaires on symptoms, psychological methods (simple reaction time, finger tapping speed and endurance, digit span, vocabulary, tracking, symbol digit, cylinders, olfactory threshold, Luria-Nebraska motor scale), neurophysiological methods (electroencephalography, event related auditory evoked potential (P-300), brainstem auditory evoked potential, and diadochokinesometry) and assessments of blood and urine concentrations of metals (aluminium, lead, and manganese). RESULTS: The welders exposed to aluminium (n = 38) reported more symptoms from the central nervous system than the control group (n = 39). They also had a decreased motor function in five tests. The effect was dose related in two of these five tests. The median exposure of aluminium welders was 7065 hours and they had about seven times higher concentrations of aluminium in urine than the controls. The welders exposed to manganese (n = 12) had a decreased motor function in five tests. An increased latency of event related auditory evoked potential was also found in this group. The median manganese exposure was 270 hours. These welders did not have higher concentrations of manganese in blood than the controls. CONCLUSIONS: The neurotoxic effects found in the groups of welders exposed to aluminium and manganese are probably caused by the aluminium and manganese exposure, respectively. These effects indicate a need for improvements in the work environments of these welders.

Increased metal release from cemented femoral components made of titanium alloy. 19 hip prostheses followed with radiostereometry (RSA).

In 19 patients the concentrations of metal were measured in serum, urine and joint fluid 2 years after implantation of uncemented commercially pure titanium acetabular cups and cemented or uncemented femoral components made of titanium alloy. A ceramic against the polyethylene articulation was used. The fixation of the components was followed with radiostereometry (RSA). Samples from 12 patients scheduled for hip or knee prostheses and without any metallic implant were used as controls. High levels of titanium were found in cemented hips and when large acetabular cups had been inserted. Increased aluminum levels were also noted in the cemented hips. Vanadium was not detected in any of the samples. Micromotions were detected in most of the implants, but the magnitude of these movements could not be used to predict the release of metal into the synovial fluid.

Mercury and selenium in workers previously exposed to mercury vapour at a chloralkali plant.

The concentrations of total mercury (B-Hg), inorganic mercury (B-IHg), and methyl mercury (B-MeHg) in whole blood, urinary mercury (U-Hg), and selenium in urine (U-Se) and whole blood (B-Se) were determined in 74 chloralkali workers previously exposed to Hg vapour, and compared with 51 age matched referents. Dental amalgam state, fish consumption, and exposure related indices were studied with regard to the determined elements. A significant relation between the surface of dental amalgam and U-Hg (Pearson's r = 0.63, p < 0.001) was found among the referents. Mean U-Se was significantly lower (p < 0.001) among the subjects previously exposed to Hg (34.1 nmol/mmol creatinine) compared with that for the referents (42.6 nmol/mmol creatinine). A significant negative relation between the cumulative Hg dose and U-Se was also found. The mechanisms and the clinical significance of these findings are not clear. No relation between current U-Hg and previous occupational exposure to Hg was found among subjects in whom exposure had ceased more than one year before the study.

Speciation of mercury in human whole blood by capillary gas chromatography with a microwave-induced plasma emission detector system following complexometric extraction and butylation.

Methyl- and inorganic mercury were extracted from human whole blood samples, as their diethyldithiocarbamate complexes, into toluene and butylated by using a Grignard reagent. The mercury species were then separated by gas chromatography (on a 12 m non-polar DB-1 capillary column) and detected by a microwave-induced plasma atomic emission spectrometric (GC-MPD) system. The accuracy and precision of the proposed method were established by the analysis of Seronorm lyophilized human whole blood standards for methyl- and inorganic mercury. No statistical difference (t-test) between the sum of these two species determined by the GC-MPD based method and the recommended total mercury concentrations in the Seronorm samples was observed. Results for the determination of methyl- and inorganic mercury in 60 controls and 90 previously occupationally exposed (to inorganic mercury) workers are presented to illustrate the practical utility of the proposed method. No significantly elevated inorganic mercury concentrations between the two groups were evident.

Dietary citric acid enhances absorption of aluminum in antacids.

Ten healthy men ingested, twice daily between meals, during each of the seven-day experimental periods: (a) citric acid (as lemon juice), (b) Al(OH)3, or (c) Al(OH)3 + citric acid. Whole blood sampled after each dietary period was analyzed electrothermally after digestion with nitric acid. Moderate, but significant, increases in mean Al concentrations as compared with pretreatment values [5 (SD 3) micrograms of Al per liter] were seen after ingestion of either citric acid or Al(OH)3: 9 (SD 4) and 12 (SD 3) micrograms/L, respectively. Ingestion of both Al(OH)3 and citric acid resulted in a more pronounced, highly significant (p less than 0.001) increase in Al concentrations, to 23 (SD 2) micrograms Al/L, probably owing to formation and absorption of Al-citrate complexes.

Influence of dietary factors on aluminium absorption and retention in the brain and bone of rats.

Young adult male Sprague-Dawley rats were treated by gavage for 10 weeks (3-times weekly) with aluminium 100 mg/kg b.wt. in the form of Al-hydroxide (Novalucol), Al-citrate, Al-hydroxide together with citric acid or with tap water (controls). Male rats aged 13 months were gavaged for 11 weeks 3-times a weak with black currant soup (0.8 ml/kg b.wt.) stored 19 days in either aluminium or stainless steel saucepans. The brain cortex, bone and blood (young adults only) of each rat were analysed for Al using graphite furnace atomic absorption spectroscopy. The rats treated with Al-citrate and in particular rats treated with Al-hydroxide + citric acid showed a significant increase of Al concentrations in all the tissues studied. In the latter group the mean Al concentrations were elevated at 0.039 micrograms Al/g wet weight (controls 0.005 micrograms/g) 0.092 micrograms/g (0.016 micrograms/g) and 26.6 micrograms/g (0.22 micrograms/g) in the blood, brain and bone, respectively. After treatment with Al-hydroxide alone only the bone showed a moderate increase of Al-concentration. No significant differences were found in the brain and bone Al levels of the rats given fruit soup from aluminium saucepans (containing 17 mg Al/l) or stainless steel saucepans (0.4 mg Al/l).

Aluminium concentrations in the brain and bone of rats fed citric acid, aluminium citrate or aluminium hydroxide.

Male Sprague-Dawley rats were treated daily by gastric intubation (6 days/wk) with 100 mg aluminium/kg body weight in the form of aluminium hydroxide (9 wk) or aluminium citrate (4 wk), with citric acid (4 wk) or with tap-water (control, 9 wk). Young adult and aged Wistar rats were treated with 100 mg aluminium/kg body weight as aluminium hydroxide or with carboxymethylcellulose (vehicle controls). The cerebral cortex, hippocampus, cerebellum and samples of bone from each rat were analysed for aluminium, after digestion with nitric acid, using graphite furnace atomic absorption spectroscopy. The mean aluminium concentrations detected in the control Sprague-Dawley rats were 0.013-0.022 microgram/g wet weight in the various brain regions and 0.355 microgram/g in the bone. No significant increase in tissue aluminium concentrations was observed in Sprague-Dawley or Wistar rats after treatment with aluminium hydroxide. However the rats treated with aluminium citrate showed significantly increased concentrations of aluminium in all the brain regions studied (0.057-0.121 microgram A1/g) and in the bone (12.9 micrograms A1/g). Elevated aluminium concentrations in the cerebral cortex and bone were also observed in the animals fed citric acid suggesting possible absorption of the citrate chelate presumably formed with the traces of aluminium present in the diet.

Evaluation of some critical factors affecting determination of aluminum in blood, plasma, or serum by electrothermal atomic absorption spectroscopy.

A digestion procedure involving nitric acid is described for determination of aluminum in blood, serum, and plasma by graphite-furnace atomic absorption spectroscopy. Contamination was not a severe problem if all operations were performed in a dust-free atmosphere. Conditions for such determination of aluminum in blood were optimum when the L'vov platform technique was used and hydrogen added to the inner gas flow of the furnace. We discuss the importance of adequate correction for nonspecific absorbance when this technique is used close to the detection limit. The blank value for the overall procedure was 1.0 (SD 0.59) micrograms/L (n = 22). We applied the method to frozen whole blood, plasma, and serum samples. For whole-blood samples from 11 different healthy subjects the mean value was as low as 1.6 (SD 1.29) micrograms of AI per liter (n = 22).

Rapid determination of antimony in steel by flameless atomic-absorption.

A method for the determination of 1-30 ppm or more of Sb in steel by using flameless atomic absorption has been developed. The sample was dissolved in aqua regia and 10 mul were pipetted into the Massmann-type furnace. It was shown that interferences from HCl, HNO(3), Ni and Fe could be eliminated if oxygen was excluded and the heating rate was sufficiently high. Chromium was added to the samples and standards to compensate for its influence. Cu, Co, Mn, Ti and Sn did not interfere. An intercomparison with other laboratories showed that this method gives the same result as extraction with TOPO in MIBK. The time for a complete analysis including dissolution was 15 min.