Total Chromium Levels Research Articles

A MWCNTs@CuAl2O4@SiO2 Nanocomposite for the Speciation of Cr(III), Cr(VI), and Total Chromium Prior to High-Resolution Continuum Source Flame Atomic Absorption Spectrometric Determination

A solid-phase microextraction (SPME) method had been applied to speciate chromium in natural and wastewater samples. MWCNTs@CuAl2O4@SiO2 nanocomposite was synthesized by sol–gel and calcination methods and then characterized using SEM, FTIR, and XRD techniques. MWCNTs@CuAl2O4@SiO2 was used to extract Cr(VI) as pyrrolidine dithiocarbamate chelates. Some analytical parameters involving pH, ligand (APDC) and adsorbent amounts, sample initial and final volume, and the effects of matrices were tested and optimized. For the oxidation of Cr(III) to Cr(VI), potassium permanganate was used, and after that, the presented method was applied to determine the total chromium levels. The calculations were carried out to obtain Cr(III) concentration by finding differences between total chromium and Cr(VI) concentrations. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 6.2 µg L−1 and 20.8 µg L−1, respectively. The proposed method was successfully applied for chromium speciation in wastewater samples.

Toxic element contaminations of prenatal vitamins

The detrimental effects of gestational and lactational exposure to adverse chemical agents are gathering increasing attention. In our study, the presence of toxic heavy metals in several prenatal vitamins from six brands available in supermarkets and pharmacies was measured using ICP mass spectrometry. Several toxic heavy metals were detected, some at levels that could have potential toxicity to the fetus and the mother as well. Previous studies have also detected toxic heavy metals in prenatal and other vitamins. One of the reasons for toxic heavy metals in “natural vitamins” sold to consumers is that they are produced from naturally grown material and not synthesized. They are likely exposed to the heavy metals from the ground that they are grown in and there has not been any significant attempt to get rid of them before the vitamin pill was sold to consumers. Thus, this problem is not an isolated issue and regulatory agencies should be dealing more aggressively than they have been doing. In fact, several papers have already been published showing similar findings as we are reporting here. The vitamin pills we analyzed have elevated levels of boron, aluminum, molybdenum, barium, lead, titanium, nickel, arsenic, strontium, and cadmium. The levels of total chromium were also elevated but we did not separately determine Cr(III) and the much more hazardous Cr(VI), because of the tedious procedure required to separate these two forms of Cr.

Analysis of liquid waste in weaving home industry at Nusa Penida, Klungkung, Bali, Indonesia

Introduction: The existence of regulations using clothing made from traditional Balinese fabrics cloth called “endek” has caused the demand for woven fabrics to increase. One of the traditional woven fabric handicrafts starting to be recognized and favored by the public is the Cepuk and Rangrang woven fabric from island of Nusa Penida. Currently, liquid waste from weaving home industry activities has not been processed. The purpose of the study was to measure the quality of liquid waste from the weaving home industry and compare it with the quality standards of liquid waste for businesses and or textile industry activities. Method: This study was descriptive, conducted in Nusa Penida District, Klungkung Regency. The sample size was 25, taken by purposive sampling from nine craftsmen actively carrying out the production process with repetition three times. Measurement of liquid waste quality was carried out at the Laboratory of Panureksa Denpasar. The parameters examined are mandatory test parameters including physical parameters (temperature, TDS, TSS and color) and chemical parameters (total chromium, total ammonia, BOD5, COD, sulfide, oil and fat). Data analysis was carried out by comparing the measurement results with the Liquid Waste Quality Standards for Textile Industry Businesses and Activities according to Bali Governor Regulation 16 of 2016. Result: The results showed an average temperature of 27.48o C, TDS levels of 6,095.20 mg/L, TSS 1,090.76 mg/L and color 2,216.56 TCU scale. The chemical parameters showed average levels of total chromium 2.3912 mg/L, total ammonia 1.6068 mg/L, BOD5 675.84 mg/L, COD 1,286.72 mg/L, Sulfide 0.2395 mg/L, oil and fat 1,340 mg/L. Based on Bali Governor Regulation No. 16 of 2016, the parameters of temperature, total ammonia, Sulfide, Oil and Fat meet the quality standard requirements. While the parameters of TDS, TSS, color, total chrome, BOD and COD do not meet the quality standard requirements because it exceed the maximum allowable levels. Conclusion: It is recommended that weaving craftsmen carry out liquid waste treatment before disposal in the environment.

Decreased hearing levels at frequencies for understanding speech in tannery workers exposed to a high level of trivalent chromium in Bangladesh

Hexavalent chromium [Cr(VI)], which has a strong corrosive effect, has been reported to cause perforation of the eardrum. Trivalent chromium [Cr(III)] also has a weak corrosive effect. However, there has been no study on the effects of exposure to Cr, either Cr(VI) or Cr(III), on hearing levels in animals or humans. In this study, the effect of Cr(III) exposure on hearing levels was determined in a human study. Then the reproducibility of the results obtained in the human study and the etiology were investigated in an animal study. The mean levels of total chromium (t-Cr) in hair and toenails from 100 Bangladeshi tannery workers were >20-fold and >360-fold higher, respectively, than those in hair and toenails from 49 Bangladeshi non-tannery workers (office workers). Multivariate analysis revealed decreases of hearing levels (DHLs) at 1 k and 4 k Hz, frequencies that are crucial for understanding language, but not at 8 k and 12 k Hz, in the tannery workers. Since >99.99% of t-Cr in the wastewater that the workers were in direct contact with in the tanneries was Cr(III), the epidemiological results suggest Cr(III)-mediated DHLs in the tannery workers. The results of animal experiments in this study further showed that treatment with eardrops but not intraperitoneal injection with the same amount of Cr(III) that tannery workers might be exposed to resulted in DHL with a damaged eardrum in mice. Previous studies suggested that Cr(III) can directly reach the eardrums of tannery workers via droplets in the air. Cr(III) could also reach the eardrum via picking an ear canal with a finger contaminated with tannery wastewater including Cr(III). Taken together, the results of both human and animal studies suggest the risk of DHLs caused by damage of the eardrum through external exposure to Cr(III) via the ear canal.

Fabrication of monolith-based solid-phase microextraction for effective extraction of total chromium in milk and tea samples prior to HPLC/DAD analysis

A convenient, sensitive and low-cost approach for the determination of trace levels of total chromium in milk and tea samples was developed by combination of solid-phase microextraction (SPME) and HPLC/DAD. To meet the chromatographic separation and UV detection, Cr(VI) was reacted with sodium diethyldithiocarbamatetrihydrate to form Cr coordination compound. According to the chemical properties of the complex, a new sorbent based on porous monolithic material (PMM) was fabricated and employed as the extraction phase of SPME. The prepared PMM displayed satisfying enrichment ability for Cr complex. Under the most appropriate parameters, the linear ranges for chromium were 1.0–500 μg/kg and 0.5–300 μg/kg in milk and tea samples, respectively, with good correlation coefficients (R2 greater than 0.99). The limits of detection for chromium were as low as 0.11 μg/kg and 0.092 μg/kg in milk and tea samples, separately. The RSDs for method precision were in the range of 0.23–8.6%. The reliability and applicability of introduced method was successfully demonstrated by quantification of low contents of total chromium in milk and tea samples. The recoveries at three fortified levels varied from 83.4% to 112%, and the RSDs (n = 3) were in the range of 2.1% and 8.9%. Compared with existing methods, the current approach exhibited some merits such as satisfactory sensitivity, low consumption of sample and high cost effectiveness.

Development and validation of a single run method based on species specific isotope dilution and HPLC-ICP-MS for simultaneous species interconversion correction and speciation analysis of Cr(III)/Cr(VI) in meat and dairy products

This study presents the development, validation and application of a new analytical approach for the simultaneous speciation analysis of Cr(III) and Cr(VI) in meat and dairy products by high-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) and double spike species specific-isotope dilution (SS-ID). The species extraction was achieved by sequential complexation of Cr(III) with ethylenediaminetetraacetic acid (EDTA) and of Cr(VI) with 1,5-diphenylcarbazide (DPC) in the same analytical run. The HPLC separation of complexed species was carried out using a short (5 cm) microbore anion-exchange HPLC column and a mobile phase consisting of 0.01 mol L−1 HNO3 + 2.5% (v/v) MeOH + 0.30 mol L−1 EDTA (pH = 2) in isocratic elution mode with excellent baseline separation achieved in less than 3 min. The method was validated by means of the accuracy profile approach by carrying out 6 measurement series in duplicate on (six) different days over a timespan of two months. The quantification limit was 0.013 μg kg−1 for Cr(III) and 0.049 μg kg−1 for Cr(VI), respectively. The measurement bias corresponding to the validity domain ranged from 0.01 to 0.11%, whereas the coefficient of variation in terms of repeatability (CVr) varied from 2.9 to 11.6% (depending on the analyte level) for Cr(III) and from 6.7 to 11.8% for Cr(VI). Similarly, the coefficient of variation in terms of intermediate reproducibility (CVR) ranged from 6.8 to 13% for Cr(III) and from 6.8 to 25.9% for Cr(VI), respectively. The method was successfully applied to the analysis of a selection of food samples such as baby and semi-skimmed milk and steak beef samples. Cr(VI) was not quantified in any of these samples while Cr(III) levels ranged between 2.7 and 4.7 μg kg−1, which were comparable with the levels of total chromium analysed in the same samples by ICP-MS (accredited method). The method presented here with combined use of species specific isotope dilution and sequential species complexation is a powerful analytical tool for accurate and precise quantification of Cr(III) and Cr(VI) at trace levels and allows for correction of any species interconversion during sample preparation.

Cr(VI) and Cr(III) in milk, dairy and cereal products and dietary exposure assessment

ABSTRACTMilk, dairy and cereal products are the main contributors to total chromium (Cr) dietary exposure in France (up to 42% for children), but there have been no assessments regarding dietary exposure to Cr(VI) or Cr(III) to date. To assess dietary exposure, total chromium and Cr(VI) were determined in 68 different brands and origins of milk, dairy and cereal products. Cr(VI) was not detected in these samples despite the very high sensitivity of the method used. It was therefore assumed that total chromium is only present in the Cr(III) form. Total chromium levels were quantified in 58% of milk and dairy products and 76% of cereal products. The highest mean levels were found in breakfast cereals and cheese (269 and 25 µg Cr /kg fresh weight, respectively). The findings pointed out that the dietary exposure levels of Cr(III) and Cr(VI) were well below the health-based guidance values.

Community health perceptions and human environmental exposure to chromium contamination in a small New Jersey City.

Following a 1983 chromic acid (hexavalent chromium [CrVI]) spill from a Garfield, NJ electroplating plant, CrVI-contaminated water was found in a local firehouse basement in 1993. An ATSDR public health advisory was issued for the plant site in 2010, and from 2008-2015, fourteen residential properties have required remediation to address CrVI-contaminated dust in the basements. As part of the Community Outreach and Engagement Core of the NYU NIEHS Center, seventytwo Garfield residents aged 18-65 years, participated in a community survey with the goal of identifying concerns related to environmental and community health. Thirty-two percent responded that they 'didn't know' if they were exposed to chemicals or pollutants where they live. This finding suggests a limited awareness of environmental chemical exposures, chromium contamination and/or potential exposure to CrVI. Furthermore, toenail clippings were collected from forty-seven Garfield residents and analyzed for total chromium levels to assess potential long-term exposure. On average, residents living on/inside the contaminated plume area had higher total chromium levels in their toenail clippings than residents living outside the plume area. However, chromium levels for all participants were within the range of historical normal. This study highlights the value of partnerships between environmentally-impacted community's and academic scientists working together to identify potential contaminant exposures and address public health concerns through research and environmental health education.

The simultaneous detection of trivalent & hexavalent chromium in exhaled breath condensate: A feasibility study comparing workers and controls.

The analytical method outlined in this feasibility study has been used to show that trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) can be detected and measured in exhaled breath condensate (EBC) samples. EBC samples and urine samples were collected from a cohort of 58 workers occupationally exposed to hexavalent chromium compounds and 22 unexposed volunteers (control group). Levels of Cr(III) and Cr(VI) were determined in EBC samples and total chromium levels were determined in urine samples. Pre and post working week samples for both EBC and urine were collected in tandem. Total chromium in urine samples was analysed by inductively coupled plasma mass spectrometry (ICP-MS). Analysis of Cr(III) and Cr(VI) in EBC samples used a hyphenated micro liquid chromatography (μLC) system coupled to an ICP-MS. Separation was achieved using an anion exchange micro-sized column. The results showed that the occupationally exposed workers had significantly higher levels of Cr(III) and Cr(VI) in their EBC samples than the control group, as well as higher levels of total chromium in their urine samples. However, for the exposed workers no significant difference was found between pre and post working week EBC samples for either Cr(III) or Cr(VI). This study has established that Cr(III) and Cr(VI) can simultaneously be detected and measured in 'real' EBC samples and will help in understanding inhalation exposure.

Valorização agronómica de resíduos da produção de pasta de papel

Composting the organic waste from pulp production and its land application is an option to get an agronomic valorisation of these by products. This work aims to quantify the effects of a composted pulp waste (wood fiber and sludges from primary and secondary treatment of wastes) application to the soil. A pot trial was conducted, at controlled conditions, on a LPli soil, and with lettuce (Lactuca sativa L.) as test plant. It was applied five experimental treatments, a control and four application rates (equivalent to 25, 50, 75 and 100 t ha-1).The application of this product to the soil led to increases in lettuce yield. No phytotoxic effects were observed, even when given the highest dose (equivalent to 100 t ha-1). The composted pulp waste acted both as an organic fertilizer and a liming material, giving rise to significant responses in relation to the soil organic matter and soil pH, directly proportional to the dose applied. The product under study also contributed to the increased availability of nutrients, such as nitrogen and phosphorus, and showed to be a source of calcium for the plant. The application of the compost to the soil, even at very high doses did not result in significant increases (p> 0.05) in the levels of “total” chromium, nickel and lead in the soil. Concerning the other heavy metals analyzed (Cd, Cu, Zn and Hg) only slight changes were observed, never exceeding the permissible values in soils where it wants to apply this type of product.

Heavy Metal Residues in the Bottom-Ash of Incinerators Treating Health-Care Waste: A Case of the Two National Teaching and Referral Hospitals in Kenya

Incinerated medical waste residue has more heavy metals than municipal solid waste which if not well disposed of, could pollute the environment and pose a great danger to public health. A study was done on incinerators at Kenyatta National Hospital – Nairobi and Moi Teaching and Referral Hospital – Eldoret to assess levels of total chromium, cadmium, mercury, lead and silver from the bottom ash. Atomic absorption spectrophotometer was used for analysis. At KNH, incinerator bottom ash had mean concentrations of 5297, 140, 4299, 2092 and 57 mg/kg of total chromium, cadmium, lead, silver and mercury respectively. At MTRH, the concentrations in the ashes of 3870, 250, 4340, 1360 and 40 mg/kg of total chromium, cadmium, lead, silver and mercury were found. These exceeded the maximum limits specified by the Kenyan National Environmental Management Agency and European Union Standards for ordinary disposal. Regular quality monitoring of heavy metals in bottom ash of the two institutions’ incinerators to guide safe disposal of the residues was not practiced.

Iron-rich Oklahoma clays as a natural source of chromium in monitoring wells

Water samples, drawn from groundwater monitoring wells located southeast of Oklahoma City, OK, were found to contain elevated concentrations of total chromium with an apparent source localized to the area surrounding each well. Since these monitoring wells are located in areas with no historic chromium usage, industrial sources of chromium were ruled out. Water testing was performed on twelve monitoring wells in the area that historically had elevated total chromium concentrations ranging from 10-4900 micrograms per litre. Filtered water samples were found to be free of chromium contamination, indicating that the source of the chromium is the suspended solids. Analysis of these solids by acid digestion and a sequential extraction technique revealed that the chromium was primarily associated with iron-containing solids. X-ray diffraction identified goethite, an iron oxide hydroxide, as the dominant iron-containing phase in the suspended solids. The mineralogy in this region is dominated by interbedded red-bed sandstone and mudstone whose mineral content includes mixed-layer illite-smectite, hematite, goethite, gypsum and dolomite. Elemental analysis of soil samples collected as a function of depth in the locale of the monitoring wells indicated that the iron rich clays contain a natural source of chromium. The elevated levels of total chromium are most likely due to the dissolution of silica and alumina from the chromium containing iron clays in the basic well water, resulting in the release of fine suspended solids that naturally have high chromium concentrations. These results should be applicable to other areas containing iron-rich clays.

Hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale ( Eubalaena glacialis) lung and testes fibroblasts

Although hexavalent chromium is a known genotoxic agent in human and terrestrial mammals and is present in seawater and air, its effects on marine mammals including the endangered North Atlantic right whale are unknown and untested. The present study investigated the cytotoxic and genotoxic effects of hexavalent chromium in primary cultured North Atlantic right whale lung and testes fibroblasts and levels of total chromium in skin biopsies from North Atlantic right whales. Cytotoxicity was measured by clonogenic survival assay. Genotoxicity was measured as production of chromosome aberrations. Tissue chromium levels were determined from skin biopsies of healthy free-ranging whales in the Bay of Fundy using inductively coupled plasma optical emission spectroscopy. Hexavalent chromium-induced concentration-dependent increases in right whale lung and testes fibroblast cytotoxicity with the testes more sensitive to the cytotoxic effects. It also induced concentration-dependent increases in chromosomal aberrations in both cell types with no significant difference in sensitivity. Skin biopsy data indicate that North Atlantic right whales are exposed to chromium and accumulate a range of 4.9–10 μg Cr/g tissue with a mean of 7.1 μg/g. Hexavalent chromium is cytotoxic and genotoxic to North Atlantic right whale cells. The whales have tissue chromium levels that are concerning. These data support a hypothesis that chromium may be a concern for the health of the North Atlantic right whales. Considering these data with chromium chemistry, whale physiology and atmospheric chromium levels further suggest that inhalation may be an important exposure route.

Alternative chromium reduction and heavy metal precipitation methods for industrial wastewater

AbstractA study of alternative chromium‐reduction and heavy‐metal precipitation methods was performed on wastewater generated by a metal‐cleaning facility. Four existing chromium‐reduction treatment methods were tested on the wastewater samples: treatment with (1) sodium metabisulfite, (2) ferrous sulfate, (3) zero‐valent iron, and (4) dimethyl dithio carbamate, ferrous sulfate, and aluminum/chloride. We found that the first two methods are more effective in chrome reduction, while the last method achieved similar reduction results but produced more sludge than any of the other methods. Our results also indicated that when ferrous sulfate was used as a chrome reduction reagent at a low initial pH (2 to 3), the competitive oxidation reaction of ferrous ions with dissolved oxygen in solution is insignificant.When iron powder was used to reduce hexavalent chromium to trivalent chromium, we found that (a) when the sample containing low levels of total chromium (⩽ 1.54 × 10− 4 mole/liter) was mixed properly with zero‐valent iron powders at a low pH (4 to 5), the total chromium concentration could be reduced to 1 mg/l in 3 hours; and (b) the chrome absorption‐reduction efficiency is limited by the transport process of Cr(VI) from the bulk of the wastewater to the surface of the iron powder. In a leaching test of used iron powder filtered from the treated wastewater, we also found that most of chromium absorbed on the iron powder was very stable, and only low Cr(VI) was detected in the leachate.

Risk assessment of chromium and arsenic in date palm leaves used as livestock feed

Appreciable levels of total chromium (Cr) and arsenic (As) were found (by emission spectroscopy) in date palm leaves, which form a significant ingredient in livestock feed. The levels in the fruit were considered safe for human consumption. Our work involved evaluation of the distribution of these elements in the leaves during the developmental stages of the fruiting season. Thirty-six leaf specimens of the Fard cultivar were collected 9, 15 and 20 weeks, respectively, after pollination and subjected to a standard digestion procedure. Sample masses of typically 1 g (dry weight) were prepared in 25 ml dilute acid solution and investigated for trace levels of Cr and As by ICP-AES. Eleven soil samples collected at random during the growth stages were subjected to a similar digestion procedure and analysis. According to the literature, the permissible mean levels of Cr and As in plants are 200 and 80 ng/g (dry weight), respectively. We used these values as our guideline to assess the “risk” levels in our samples of interest. In the case of Cr, about 45% of the specimens possessed levels between 250 and 700 ng/g, while a significant number produced levels between 1000 and 5000 ng/g. With regard to As, about 70% of the samples were above the documented permissible mean value. As a result of the unusually high Cr concentrations in some cases, the feasibility of Cr “accumulation” in the leaves was examined. Insects and other organisms subsist on the leaves and an added concern was the accumulation of these elements in the food chain. The study formed an interesting contribution to environmental research, and the impact of our assessment on the environment is discussed.

Heavy metal content of newspapers: longitudinal trends

Examines whether there are any environmental or health implications associated with the increased use of colour in newspapers, if the newspapers are reused or recycled. New heavy metal analyses of UK daily newspapers from 1992, 1996 and 1998 are reported. Lead, mercury and cadmium were found to be below their measurement detection limits (4ppm, 5ppm and 1ppm respectively) in nearly all samples. Barium and total chromium levels were highest in supplements printed on “glossy” paper. Copper was present at levels around 20‐30ppm in the standard newsprint sections and at levels of 80ppm or more in the supplements. Copper concentrations increased by 33‐40 per cent between 1992 and 1998 which correlated well with the increased colour content. A scientific appraisal and review showed that the heavy metal contents of newspapers are highly unlikely to pose any environmental risk or to have any health implications.

Detergents and bleaches are sources of chromium contact dermatitis in Israel.

Total chromium levels were determined in 38 detergents and 12 bleaches on the market in Israel (45 locally produced, 5 imported). The samples were analyzed by Zeeman-corrected graphite furnace atomic absorption spectrophotometry. Chromium levels were higher than 5 ppm in 28 (56%) of the 50 products, from 1 to 5 ppm in 16 (32%), and lower than 1 ppm in only 6 (12%). Among the 5 imported products, only 1 had a chromium level below 1 ppm and the other 4 (1 from Germany, 3 from the USA) had high levels. Since a most 90% of the detergents and bleaches examined contained chromium levels higher than 1 ppm, it is concluded that these consumer products may be the cause of the high incidence of chromium sensitivity in Israel.

In vivo formation of chromium(V) in chick embryo liver and red blood cells.

In order to understand the possible role of reactive intermediates in the formation of tissue-specific DNA damage by chromium(VI), electron paramagnetic resonance spectroscopy was used to study the in vivo formation of chromium(V) in the liver and red blood cells of 14 day chick embryos following treatment with chromium(VI). In vivo administration of sodium dichromate onto the inner shell membrane of 14 day chick embryos resulted in the formation of a persistent chromium(V) species in liver cells (g = 1.987). The intensity of the chromium(V) signal in liver cells plateaued at 70 min and persisted for 240 min after treatment with chromium(VI). The dependence of chromium(V) formation on the dose of sodium dichromate administered to the embryo was clearly different in liver versus red blood cells. Chromium(V) was detected in red blood cells only at high doses of sodium dichromate (0.50-0.60 mmol/kg), whereas chromium(V) was undetectable in red blood cells at lower doses of sodium dichromate (0.10-0.30 mmol/kg) which produced clear evidence for chromium(V) in liver. Uptake studies showed that total chromium levels in red blood cells were 10-fold greater than in liver cells, and that up to 10% of the total chromium existed as chromium(V) in liver and red blood cells in vivo. Depletion of glutathione by pretreatment of embryos with L-buthionine-S,R-sulfoximine (BSO) for 24 h prior to treatment with a high dose of sodium dichromate (0.60 mmol/kg) caused both a decrease in the levels of chromium(V) species produced and a decrease of chromium uptake into red blood cells 50 min after treatment. At this high dose of chromium(VI), BSO pre-treatment had no effect on the level of the chromium(V) or on chromium uptake into liver cells after a 70 min incubation period. Thus, the concentration of chromium(V) inside the cell correlated with the levels of chromium taken up into the cell. Chromium(V) may be the form of chromium which is responsible for induction of DNA damage following in vivo administration of sodium dichromate.

Chromium in urine, serum and red blood cells in the biological monitoring of workers exposed to different chromium valency states

Using personal air sampling exposure to hexavalent and trivalent chromium was measured in 22 workers mainly exposed to Cr(VI) and in 15 workers mainly exposed to Cr(III) as basic chromium sulphate. Determination of Cr(VI) in the urine of all the subjects using a selective technique by ETA-AAS and liquid anion exchangers failed to show detectable amounts of the hexavalent form, the detection limit of the technique being 0.05 μg/L. A clear relationship between exposure and postshift urinary total chromium was found in subjects exposed to Cr(VI), while urinary levels in workers exposed to chromic sulphate high concentration proved lower. Determination of total chromium in serum and red blood cells showed a significant increase of chromium levels in erythrocytes of workers exposed to Cr(VI) while in subjects mainly exposed to Cr(III) an increase of the serum fraction was observed. The results demonstrate that Cr(III) is absorbed through the respiratory tract, but its kinetics and distribution in the body are not the same as for Cr(VI), and are not adequately monitored by short-term urinary determinations. Oxidation states of chromium largely influence uptake, mechanism of absorption, transport and organ distribution as well as toxicity of chromium-containing compounds. In particular, hexavalent derivatives are known to induce adverse effects, both acute and chronic, in occupationally exposed subjects, while there is little conclusive evidence for toxic effects caused by trivalent chromium compounds. Biological monitoring of exposure to chromium(VI) has usually been performed by determining total chromium levels in urine, whereas biological monitoring data in subjects occupationally exposed to Cr(III) are still scanty. In workers exposed to high levels of chromium(III) oxide and sulphate, Korallus et al. (ref.1) found only slight increases in urinary chromium concentrations in spot samples, while Minoia et al. (ref.2) reported elevated levels of chromium in urine of workers exposed to trivalent chromium. Kiilunen et al. (ref.3), in workers exposed to chromium(III) lignosulphonate, evidenced pharmacokinetic parameters reproducing those of water-soluble hexavalent chromium compounds. More recently, Aitio et al. (ref.4) found high concentrations of chromium in the urine of two workers exposed to trivalent chromium sulphate. Our study was aimed to evaluate the relationship between concentrations of hexavalent and trivalent chromium in workroom environment and chromium levels in urine, serum and erythrocytes of workers with prevalent exposure to both chromium(VI) and chromium(III), in order to assess whether the excretion rate of chromium and its distribution in blood compartment differ in relation to oxidation states of the metal.

The determination of chromium-50 in human blood and its utilization for blood volume measurements

Possible relationships between insufficient blood volume increases during pregnancy and infant mortality could be established with an adequate measurement procedure. An accurate and precise technique for blood volume measurements has been found in the isotope dilution technique using chromium-51 as a label for red blood cells. However, in a study involving pregnant women, only stable isotopes can be used for labeling. Stable chromium-50 can be determined in total blood samples before and after dilution experiments by neutron activation analysis (NAA) or mass spectrometry. However, both techniques may be affected by insufficient sensitivity and contamination problems at the inherently low natural chromium concentrations to be measured in the blood. NAA procedures involving irradiations with highly thermalized neutrons at a fluence rate of 2·1013 n·cm−2·s−1 and low background gamma spectrometry are applied to the analysis of total blood. Natural levels of chromium-50 in human and animal blood have been found to be <0.1 ng/ml; i.e., total chromium levels of <3 ng/ml. Based on the NAA procedure, a new approach to the blood volume measurement via chromium-50 isotope dilution has been developed which utilizes the ratio of the induced activities of chromium-51 to the iron-59 in three blood samples taken from each individual, namely blank, labeled and diluted labeled blood.