Determination of total chromium in tanned leather samples used in car industry.

Despite the high competition of synthetic fibers leather is nowadays still widely used for many applications. In order to ensure a sufficient stability of the skin matrix against many factors, such as microbial degradation, heat and sweat, a tanning process is indispensable. Using chromium (III) for this purpose offers a multitude of advantages, thus this way of tanning is widely applied. During the use of chromium tanned leather as clothing material as well as for decoration/covering purposes, chromium is extracted from the leather and may then cause nocuous effects to human skin, e.g. allergic reactions. Thus the knowledge of the total chromium content of leather samples expected to come into prolonged touch with human skin is very important. In car industry leather is used as cover for seats, steering wheel and gearshift lever The chromium contents often chromium tanned leather samples used in car industry were determined. First all samples were dried at 65 degrees C overnight and then cut in small pieces using a ceramic knife, weighed and analyzed by inductively coupled plasma--optical emission spectrometry (ICP-OES) after acidic microwave assisted digestion. The total chromium amounts found were in the range from 19 mg/g up to 32 mg/g. The extraction yield of chromium from leather samples in sweat is approximately 2-7%. Thus especially during long journeys in summer chromium can be extracted in amounts which may cause nocuous effects for example on the palm of the hands or on the back.

Selected urinary metal reference concentrations of the Viennese population - urinary metal reference values (Vienna).

Reference concentrations of metals are the basis for risk assessment studies and for estimation of type and magnitude of environmental and occupational exposure. Urine is often used as a specimen for monitoring studies, as it plays an important role in the elimination of various substances from the body and in addition it can be collected easily. Therefore, the urinary levels of seven trace elements (Al, Co, Cr, Mo, Nb, Ni, Ti) were determined by atomic spectrometric methods (ICP-MS and GFAAS) in 100 urine samples of the Viennese population. The obtained creatinine adjusted concentrations (medians) are in microg/g 6.1, 1.5, 1.1, 46.2, 0.4, 0.1, and 8.0 for Al, Co, Cr, Mo, Nb, Ni, and Ti, respectively.

Four-year study of cobalt and chromium blood levels in patients managed with two different metal-on-metal total hip replacements.

BACKGROUND: Metal-on-metal total hip prostheses will produce a certain amount of wear debris. This results in increased whole-blood metal levels, which may cause adverse effects. It is not known to what extent the problem has been overcome by advances in alloy technology. METHODS: In 259 patients who with total hip replacement, blood cobalt and chromium concentrations were measured with atomic absorption spectrophotometry over a period of four years after arthroplasty. Of the patients enrolled in the study, 131 had been managed with a METASUL cobalt-chromium alloy metal-on-metal bearing combination, while 128 had been given a SIKOMET-SM21 cobalt-chromium alloy metal-on-metal combination. The control group consisted of 31 age- and gender-matched subjects. RESULTS: Compared with the controls, all the patients had higher cobalt and chromium levels. Cobalt concentrations were up to 50 times higher, while chromium concentrations were up to 100 times higher. CONCLUSIONS: Both systems showed evidence, in the whole-blood samples, of wear debris production by the implants. Therefore, patients managed with metal-on-metal bearing combinations should be carefully monitored in order to ensure that any local or systemic complications are detected early on.

Hydrophobic interaction chromatographic separation of proteins in human blood fractions hyphenated to atomic spectrometry as detector of essential elements.

The binding of metals to proteins in blood fractions was investigated applying hydrophobic interaction chromatography (HIC) for protein separation and graphite furnace atomic absorption spectrometry (GFAAS) as the element specific detector. For the semi-preparative separation of metalloproteins in erythrocytes and blood plasma, a HIC column (Fractogel EMD Phenyl I (S) 150 mm x 10 mm I.D.) was adapted. The separation column was calibrated with the same four standard proteins as used in Pomazal et al. [Analyst 124 (1999) 657]. The sample injection volume and the ammonium sulphate gradient set-up were optimized: 20 or 200 microl, respectively, of blood plasma and of lysed erythrocytes were injected. The separated proteins were collected in 4-ml fractions and analyzed by GFAAS off-line. An optimization of the GFAAS measuring parameters for Cu, Mn, Fe, Zn, Co, Ni, and Cr was performed. For each element, a specific temperature program was optimized with respect to the matrix of the HIC eluate (0.02 M NaH2PO4, 1.8 M (NH4)2SO4). The obtained metal profiles of the eluate were compared with the HIC chromatograms. The limits of detection (LOD) for the elements by GFAAS were: 0.5 ng Cu/ml; 0.2 ng Mn/ml; 1 ng Fe/ml; 0.2 ng Zn/ml; 0.12 ng Co/ml; 0.2 ng Ni/ml; 0.16 ng Cr/ml. The GFAAS method enabled the detection of the proteins of interest via the metals.

Toxic and biochemical effects of zinc in Caco-2 cells.

Zinc (in relatively high concentrations) can be toxic to intestinal cells. The aim of the present study was to quanitfy cellular injury in preconfluent, colonic cancerous cells and in postconfluent, differentiating human intestinal Caco-2 cells. Cellular damage was measured by using cell proliferation, lactate dehydrogenase (LDH)-release, and apoptosis studies. Furthermore, the activities of the major antioxidative enzymes [superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase] and differentiation markers (alkaline phosphatase and aminopeptidase-N) were determined after exposure of the cells to increasing amounts of zinc sulfate. Proliferation and viability decreased in a concentration-dependent manner. A noticeable increase of LDH-release correlated to cell rounding and detachment at relatively high zinc levels (200 muM) was observed in both groups of cells. Above 100 muM of zinc, significant apoptotic activity was found in the preconfluent cells. Zinc supplementation did not alter SOD activities. However, GPx and, in part, catalase activities tended to be higher in zinc-treated cells (nevertheless the results were not significant). Differentiation markers were noticeably induced by increasing amounts of zinc, especially in the preconfluent cells. In conclusion, we suggest that the susceptibility to zinc induced damage is equal in both confluentation groups of Caco-2 cells. Risk assessment for high concentrations seems recommendable.

Pharmacological levels of copper exert toxic effects in Caco-2 cells.

Copper might be toxic to human intestinal cells because of its ability to catalyze the formation of free radicals. The aim of the present study was to quantify toxicological effects of increasing copper concentrations in preconfluent, colonic cancerous cells as well as in postconfluent, differentiating Caco-2 cells. Our results indicate that postconfluent cells might be more sensitive to copper toxicity. A significant rise of lactate dehydrogenase (LDH) release (150 microM or above) and decrease of cell proliferation (100 microM or above) with increasing copper levels was found, as compared to the control. To the contrary, preconfluent cells were not significantly affected by copper (LDH release) or, if so, only at a concentration of 250 microM (proliferation). Loss of viability and morphological changes, including loss of adherence and cell rounding, were visible after incubation with 250 microM copper in both groups. Superoxide dismutase (SOD) activities were not affected by copper. Glutathione peroxidase (GSH-Px) and catalase activities were higher in copper-treated cells, especially in the postconfluent ones (nevertheless, the results were not significant because of high standard deviations). In conclusion, we demonstrated that copper exerts intracellular, toxicological effects on both groups of Caco-2 cells, although the effects seem to be more evident in the postconfluent (enterocytelike) group. Risk assessment, especially for high concentrations, might be of special interest.

Determination of 28 selected elements in textiles by axially viewed inductively coupled plasma optical emission spectrometry.

A simple, robust and reliable analytical procedure for the determination of 28 selected elements, namely Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Hg, Mg, Mn, Mo, Na, Ni, Pb, Sc, Si, Se, Sn, Sm, Sr, Tl, V, and Zn in textile materials by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave digestion of samples was optimized and validated in this work. The total amount of elements present in textile samples was determined after microwave digestion of materials in 7 mol/L nitric acid within the optimal working program: 5 min at 150°C (power 250 W), 15 min 180°C (300 W) and 20 min at the maximum temperature of 200°C (350 W). For the quality control reasons, which were ascertained by analysis of the certified cotton trace elements reference material IAEA-V9, the ICP-OES method was optimized through several parameters: by comparing Meinhard and Gemcone Low Flow nebulizers efficiency, ranging nebulizer gas flows from 0.6 to 1.0 L/min, ranging sample flows from 0.8 to 1.2 mL/min, testing RF power from 1200 to 1400 W, detecting data acquisition time (read time) from 0 to 527 s, ranging washing (delay) time from 0 to 408 s, as well as by checking the occurring interferences for the optimal line selection. Validation included determination of linearity, selectivity, accuracy, reproducibility, precision and limits of detection calculated for all 28 selected elements of interest. The developed analytical procedure was successfully applied on textile fibers (cotton, flax and hemp) as well as on standard knitted textile sample materials (cotton and wool).

In vitro study of ingested coins: leave them or retrieve them?

BACKGROUND: Objects and notably coins are frequently swallowed by children 3 to 5 years old. Precisely how they should be managed after passing the gastroesophageal junction without causing symptoms remains controversial. This study was performed to assess dissolution of specific metals from coins immersed in simulated gastric juice. METHODS: Four types of euro and US coins were immersed in simulated gastric juice for 4, 24, 72, and 120 hours. Six metals were evaluated by inductively coupled plasma-atomic emission spectrometry. Weight loss and corrosive behavior were also determined. RESULTS: After only 4 hours, metals had dissolved from euro (Cu, 2.86-7.85 mg; Ni, 0.23-0.52 mg; Zn, 0.09-0.99 mg; Al, 0.24 mg; Sn, 0.02 mg) and US (Cu, 1.45-6.65 mg; Ni, 0-0.62 mg; Zn, 0-0.14 mg) coins. Their concentrations in simulated gastric juice peaked after 24 to 72 hours (milligrams/hours) in euro (Cu, 218/48; Ni, 82.50/72; Zn, 83.00/72; Al, 14.65/72; Sn, 0.66/72) and US (Cu, 126.50/24; Ni, 88.00/72; Zn, 149.00/24) coins. All coins underwent corrosion and weight loss (by 2.56%-4.8%). CONCLUSIONS: Coins retained in the stomach will release a number of heavy metals well known to cause dose-dependent poisoning. Studies to evaluate their toxicity and absorption are needed to optimize treatment.

Determination of Iron in Caco-2 cells by ET-AAS.

An electrothermal atomic absorption spectrometric method (ET-AAS) was developed for the direct determination of iron in intestinal Caco-2 cells after studying cell viability and proliferation using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT test). Zeeman background correction and end-capped graphite tubes with L'vov platforms were used. Samples were dissolved in dimethylsulfoxide (DMSO) and pipetted directly into the graphite tube. The preashing, pretreatment and atomization steps were optimized. The temperatures selected were 600, 1200, and 2100 degrees C, respectively. Stability measurements were performed using iron standard solutions in DMSO on the one hand and acidified cell solutions on the other. Direct measurement and standard addition were compared in order to determine possible influences of the matrix. The low detection limit of the ET-AAS method (1.3 microg/L or 3.3 microg/g) combined with the small sample quantities required are ideal for the determination of iron in cells due to the low iron content and the limited growth area of the cells. The method was developed for iron uptake studies for toxicological purposes.

Colon-specific regulation of vitamin D hydroxylases--a possible approach for tumor prevention.

Epidemiological data suggest a protective role of calcium and vitamin D against colorectal tumor pathogenesis. 1,25-dihydroxyvitamin D3 (1,25-D3) is a key determinant of calcium homeostasis, cell proliferation and differentiation. Calcium in the intestinal lumen functions as a growth regulator and may prevent cancer by direct reduction of colonocyte proliferation. While calcium or vitamin D can counteract proliferation by itself, they could also interact if nutritional calcium were to modulate colonic vitamin D synthesis. In this paper we demonstrate that colonic and renal vitamin D hydroxylases are regulated independently. When mice were fed a modified AIN-76 diet containing low dietary calcium (0.1 or 0.04%) fecal calcium content was as low as 5% of that found in mice on a 0.9% calcium containing diet. Low fecal calcium concentration enhanced proliferating cell nuclear antigen expression in the colon mucosa and reduced that of the cyclin dependent kinase inhibitor p21. While low dietary calcium did not affect colonic expression of VDR or 25-hydroxyvitamin D3 1alpha-hydroxylase (CYP27B1) mRNA, it influenced their renal expression in the expected manner by elevating the CYP27B1 expression and reducing VDR and 25-hydroxyvitamin D3 24-hydroxylase (CYP24) expression. In contrast, low calcium diets significantly augmented colonic CYP24 mRNA expression, but only in the ascending colon. This might result in reduced colonic accumulation of 1,25-D3 during hyperproliferation caused by low dietary calcium and might support site-specific tumorigenesis. The important realization that low dietary calcium by itself is a risk factor for colorectal carcinogenesis and that colonic and renal vitamin D hydroxylases indeed are regulated differently from each other will provide novel approaches for colon cancer prevention.

Toxicological effects of iron on intestinal cells.

The aim of the present study was to investigate whether iron, which is involved in the formation of free radicals in vitro, can initiate cellular injury in human intestinal cells. The effects of various concentrations of iron were studied in preconfluent, colonic-cancerogenous cells, and also in postconfluent, differentiating cells. Cellular damage was assessed using cell proliferation (serial cell counting), tetrazolium dye (MTT) uptake, lactate dehydrogenase (LDH) release and apoptosis studies based on caspase-3 activities. Also the activities of the major antioxidative enzymes, superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) were measured after the cells had been exposed to iron. Our results indicated that preconfluent cells were more susceptible to iron toxicity, as assessed by a significant reduction in cell proliferation and MTT uptake in a concentration-dependent manner compared to the control. However, no evidence for MTT uptake was observed in postconfluent cells. Caspase-3 activity, an indicator of cell apoptosis, considerably increased in preconfluent cells at high iron levels compared to the control (p < 0.05), whereas postconfluent cells were not significantly affected. LDH release was similar for both groups and was significantly higher than the control at 900 microM iron and above. SOD activities were not affected by iron in either group, whereas GPx was considerably higher in iron-treated cells in both groups compared with the control (because of relatively high standard deviations this effect was not significant). In conclusion we suggest that iron exerts its toxic effects intracellularly especially in preconfluent Caco-2 cells, whereas only high iron doses were able to alter the viability of differentiating, enterocyte-like cells.

Release of toxic metals from button batteries retained in the stomach: An in vitro study.

BACKGROUND: Ingestion of button batteries by children is a rapidly growing problem, and opinions differ on how button batteries distal to the gastroesophageal junction should be managed. The authors therefore performed an experimental study to determine the cumulative load of various toxic elements released from retained button cells in simulated gastric juice. METHODS: Eight different groups of button cells were immersed in simulated gastric juice. Analyzed elements included Al, Ba, Cd, Cr, Cu, Fe, Hg, Li, Mg, Mn, Ni, Pb, Sb, Sn, Sr, Te, TI, V, W; and Zn. Inductively coupled plasma mass spectrometry (ICP-MS) was used to evaluate the residual amounts of elements after 4, 24, 72, and 120 hours. RESULTS: At 4 hours, leakage was seen with almost all batteries, with the levels increasing in a time-dependent manner. The highest detected levels at 4 hours were 1.20 microgram for Cd, 280.51 ng for Hg, and 2.63 microgram for Pb. Dissolution, holes, and defragmentation were seen within 24 to 72 hours. Battery weight loss varied between 22 and 104 mg over the course of the study. CONCLUSIONS: Toxic elements contained in button cells are released quickly in gastric juice. This finding might change the current policy of watchful waiting or conservative management of batteries lodged in the stomach.