Cancer mortality and exposure to nickel and chromium compounds in a cohort of Italian electroplaters.

BACKGROUND: Nickel and chromium-VI compounds are carcinogens for lung cancer, although it is still debated if there is an increased risk at low levels of exposure and for other cancers. METHODS: In a cohort of 2991 Italian electroplaters, a proportion of whom were exposed to low levels of nickel and/or chromium, cumulative exposure to their compounds was obtained by multiplying average concentrations of the metals in each electroplating tank by duration of employment in the company. The association of exposure to compounds with mortality was assessed by multivariable Cox models. RESULTS: No cancer site was associated with chromium exposure controlling for nickel, whereas exposure to nickel significantly increased mortality from lung, rectal, and kidney cancers, even after adjusting for exposure to chromium. CONCLUSIONS: Study results suggest that exposure to nickel compounds may increase the risk of lung cancer even below its occupational exposure limit and indicate possible associations with other cancer sites.

Evaluation of external markers to estimate fecal excretion, intake, and digestibility in dairy cows.

The objective of this study was to compare the use of an external marker titanium dioxide (TiO2) as an alternative to chromic oxide (Cr2O3) in dairy cows. Four dairy cows were allocated in individual pens and fed concentrate supplement and Pennisetum purpureum cv. Cameroon cut daily. Fecal excretion, forage and total dry matter (DM) intakes, and digestibility were measured and estimated with TiO2 and Cr2O3. Chromic oxide overestimated and TiO2 tended to overestimate fecal excretion compared with total fecal collection. Forage and total DM intakes were overestimated by Cr2O3. The apparent DM digestibility was underestimated by Cr2O3 and TiO2. The organic matter (OM) digestibility was underestimated by both markers. There were greater mean bias, mean squared prediction error, and root of the mean squared prediction errors for all parameters estimated with Cr2O3. In conclusion, estimates using TiO2 were more precise and accurate indicating that it can replace Cr2O3 as an external marker for grazing dairy cows.

Electrochemical corrosion and surface analyses of a ni-cr alloy in bleaching agents.

PURPOSE: The aim of this study was to evaluate the corrosion behavior of a Ni-Cr dental casting alloy subjected to 10% hydrogen peroxide (HP) and 10% carbamide peroxide (CP) bleaching solutions and to determine the composition of the surface oxide layer formed on the alloy specimens. MATERIALS AND METHODS: Ten cylindrical specimens (4 mm in diameter × 25 mm in height) were cast from a Ni-Cr alloy (Wiron 99) and divided into two groups (n = 5). A potentiodynamic polarization test was used to compare the corrosion rates of specimens in HP and CP (pH = 6.5). Before cyclic polarization tests, all alloy specimens were allowed to reach a steady open circuit potential (Ecorr ) for a period of 1 hour. Then tests were initiated at 100 mV versus standard calomel electrode (SCE) below Ecorr and scanned at a rate of 1 mV/s in the anodic direction until reaching 1000 mV over the Ecorr value. The scan then was reversed back to the Ecorr of the specimens. The open circuit potentials (Ecorr ) and the current densities (Icorr ) were determined using the anodic Tafel regions extrapolating from the curves. Differences in Ecorr and Icorr were determined using one-way ANOVA (α = 0.05). In addition, corrosion rates were calculated from these curves. Before and after polarization tests, a scanning electron microscope (SEM) examination accompanied by energy dispersive X-ray spectroscopy (EDS) was used to analyze the surface morphology. The surface characterization of the passive film formed on alloy specimens was also performed by using X-ray photoelectron spectroscopy (XPS). RESULTS: In this study, bleaching agents had an effect on the anodic process for two groups. Although no statistical difference was identified between the groups for both corrosion parameters, results indicated that the effect of CP on the corrosion behavior was less than that of HP. These results agreed with the SEM observations. XPS data showed that oxide layers formed on all groups contained mainly Cr2 O3 , NiO, and MoO3 , and the amounts of oxides formed on CP-treated specimens were higher than HP treated ones. Also, molybdenum rates were increased with CP application compared to HP. CONCLUSIONS: The comparison of the effects of the two bleaching agents at 10% showed that the alloy suffered less corrosion with CP than HP. This result was also confirmed by the SEM and XPS data. The presence of Mo on the oxide layer affected the oxide layer, leading to lower corrosion rates.

Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods. 3. Synthesis, characterization, and detection of different crystal forms of the chrome yellow pigment.

The painter, Vincent van Gogh, and some of his contemporaries frequently made use of the pigment chrome yellow that is known to show a tendency toward darkening. This pigment may correspond to various chemical compounds such as PbCrO(4) and PbCr(1-x)S(x)O(4), that may each be present in various crystallographic forms with different tendencies toward degradation. Investigations by X-ray diffraction (XRD), mid-Fourier Transform infrared (FTIR), and Raman instruments (benchtop and portable) and synchrotron radiation-based micro-XRD and X-ray absorption near edge structure spectroscopy performed on oil-paint models, prepared with in-house synthesized PbCrO(4) and PbCr(1-x)S(x)O(4), permitted us to characterize the spectroscopic features of the various forms. On the basis of these results, an extended study has been carried out on historic paint tubes and on embedded paint microsamples taken from yellow-orange/pale yellow areas of 12 Van Gogh paintings, demonstrating that Van Gogh effectively made use of different chrome yellow types. This conclusion was also confirmed by in situ mid-FTIR investigations on Van Gogh's Portrait of Gauguin (Van Gogh Museum, Amsterdam).

Chromium speciation in groundwater of a tannery polluted area of Chennai City, India.

Chromium speciation in groundwater of a tannery polluted area was investigated for the distribution of chromium species and the influence of redox couples such as Fe(III)/Fe(II) and Mn(IV)/Mn(II). Speciation analysis was carried out by ammonium pyrolidinedithiocarbamate (APDC)-methylisobutylketone (MIBK) procedure. The groundwater samples were analyzed for Cr(III), Cr(VI), and Cr(III)-organic complexes. The APDC could not extract the Cr(III)-organic complexes, but HNO3 digestion of the groundwater samples released the Cr(III)-organic complexes. The groundwater of the area is relatively oxidizing with redox potential (Eh) and dissolved oxygen (DO) ranged between 65 and 299 mV and 0.25 and 4.65 mg L(-1), respectively. The Fe(II) reduction of Cr(VI) was observed in some wells, but several wells that had Fe(II)/Cr(VI) concentrations more than the stoichiometric ratio (3:1) of the reduction reaction also had appreciable concentration of Cr(VI). This could partly be due to the oxidation of Fe(II) to Fe(III) by DO. It appears that the occurrence of Mn more than the Fe(II) concentration was also responsible for the presence of Cr(VI). Other reasons could be the Fe(II) complexation by organic ligands and the loss of reducing capacity of Fe(II) due to aquifer materials, but could not be established in this study.

Accumulation of lead, chromium, and cadmium in muscle of capitán (Eremophilus mutisii), a catfish from the Bogota River basin.

Heavy metal accumulation of lead (Pb), chromium (Cr), and cadmium (Cd) in the muscle of the catfish Eremophilus mutisii was studied in 47 specimens, captured by anglers in the Bogotá River at two sampling sites (Chocontá and Suesca) during May-October 2005. Water samples were processed for physicochemical and metal analyses. Metal accumulation in muscle (wet weight) of specimens at Chocontá and Suesca showed high levels of Pb (3.4 and 3.1 ppm, respectively), Cr (1.8 and 2.1 ppm, respectively), and Cd (0.35 and 0.48, respectively). Metal levels in waters (ppm) indicated that average Pb (0.028 Chocontá, 0.029 Suesca), Fe (0.462 Chocontá, 1.1 Suesca), and Cr (0.113 Chocontá) were above the maximum levels (MCLs) allowed in drinking waters. No extreme average values were found for pH, nitrites, alkalinity, and hardness in the waters. This study showed the importance of benthic and nonmigratory species like the capitán to evaluate the effects of heavy metals pollution. Further public health implications could be derived in the region where this investigation took place due to consumption of capitán by people in the area.

Wastewater quality of natural gas fertilizer factory, Fenchuganj and water quality of Kushiara River at the down stream.

The physical, chemical and biological characteristics of the wastewater of Natural Gas Fertilizer Factory Ltd. Fenchuganj, Sylhet were determined through extensive laboratory tests in the months of March, July, October and December of the year 2005. Concentration of Suspended Solids was within the range of 445 to 950 mg/L. Bangladesh Industrial Effluent Standards for Suspended Solids is 100 mg/L. Suspended Solids were found above the limit in all the samples. Concentration of Dissolved Solids was found to vary from 576 to 1,456 mg/L. Bangladesh Industrial Effluent Standards, for Dissolved Solids is 2,100 mg/L. Dissolved Solids were found within the limit. Concentration of BOD(5) was found to vary from 4.5 to 8.4 mg/L. Bangladesh Industrial Effluent Standards for BOD(5) is 50 mg/L. For the year 2005, the BOD(5) was found below the limit in all the samples. Dissolved Oxygen of the wastewater was found to be between 2.0 to 3.0 mg/L, which do not satisfy the standard (4.5-8 mg/L). Oil and grease concentration were found in the range of 28 to 68 mg/L, whereas the standard is 10 mg/L for discharge into the inland surface water. In 2005, concentration of Cr(+ 6) was found to vary from 0.01 to 0.156 mg/L in the wastewater. Bangladesh Industrial Effluent Standards, for Cr(+6) is 0.1 mg/L. The concentration of chromium was found above the limit in three samples. Concentration of NO(3) was found to vary from 4.5 to 15.2 mg/L in the wastewater. Bangladesh Industrial Effluent Standards for nitrate is 10 mg/L. The nitrate was found above the limit in three samples. Maximum concentration of ammonia in lagoon 1 was found 1,710 mg/L in month of December. Bangladesh Industrial Effluent Standards for ammonia nitrogen is 100 mg/L. For the year 2005, the ammonia nitrogen was found above the limit in all samples.

On-off-on fluorescent carbon dots from waste tea: Their properties, antioxidant and selective detection of CrO42-, Fe3+, ascorbic acid and L-cysteine in real samples.

In this work, we reported an economical plant-based hydrothermal method for one-pot green synthesis of water-soluble carbon dots (Tea-CDs) by using waste tea extract as a carbon source. The synthesized Tea-CDs were characterized by UV-visible, fluorescence, FT-IR, TEM, XPS and XRD. The Tea-CDs were found to remove hydroxyl and superoxide anion radical in vitro. In addition, the Tea-CDs exhibited bright blue fluorescence under UV-light (λex = 365 nm), and the fluorescence could be effectively quenched by CrO42- and Fe3+ ions. Meanwhile, the fluorescence of Tea-CDs-CrO42- and Tea-CDs-Fe3+ systems could be again easily recovered by ascorbic acid (AA) and L-cysteine (L-Cys). As an on-off-on fluorescent nano-sensor of the Tea-CDs, the sensitive detection of CrO42-, Fe3+, AA and L-Cys were all performed, showing that the good linear relationships between fluorescence intensity of Tea-CDs and concentration of all testing samples. Finally, the sensors successfully detected CrO42-, Fe3+, AA and L-Cys in commercially available real samples with satisfactory recovery ranges. The prepared sensors offer distinct advantages including low cost, simple handling, good sensitivity and high selectivity.

The hazard of chromium exposure to neonates in Guiyu of China.

Guiyu is one of the most heavily chromium-polluted areas in China due to the presence of numerous electronic waste (e-waste) recycling sites in the region. In this study, we investigate the effect of umbilical cord blood chromium levels (UCBCLs) on neonates from Guiyu and discuss chromium-induced DNA damage of cord blood lymphocyte. Umbilical cord blood samples were collected from neonates of Guiyu (in 2006, n=100; in 2007, n=100) and the neighboring town of Chaonan (in 2006, n=52; in 2007, n=50) that is associated with the fishery. UCBCLs of the neonates were determined by graphite atomizer absorption spectrophotometer. Comet experiment was used to examine lymphocyte DNA damage. Questionnaires to gauge chromium exposure were administered to the mothers of the neonates. The mean UCBCLs of neonates in the Guiyu group in 2006 and 2007 were 303.38 microg/L and 99.90 microg/L with median 93.89 microg/L and 70.60 microg/L, respectively. We observed significant differences between the results in UCBCLs of neonates in Guiyu and the control group (P<0.01). There was no significant difference of UCBCLs in neonates between 2006 and 2007 in Guiyu (P>0.05). Higher levels of chromium in neonates were found to correlate with their mothers' exposure to e-waste recycling. There were significant differences in terms of DNA damage between the Guiyu group and the control group (P<0.05). There was a correlation between DNA damage and the UCBCLs of neonates (P<0.05). There is conclusive evidence that high UCBCLs in neonates exists in e-waste recycling areas in Guiyu and that e-waste recycling activity poses serious environmental problems. Chromium pollution is threatening the health of neonates around the recycling sites.

Impact assessment of chromite mining on groundwater through simulation modeling study in Sukinda chromite mining area, Orissa, India.

The pre-Cambrian chromites ore deposits in Sukinda valley, Jajpur District, Orissa, India, are well known for chromite ore deposits. The exploitation of the ore is carried out through open cast mining method since the last few decades. In the process, the overburden and ore dumps are stored on ground surface, where leaching of chromite and other toxic element takes place particularly during monsoon seasons. This leachate may cause threat to groundwater in the vicinity. An integrated approach has been adopted to evaluate possibility of pollution due to mine seepage and leachate migration on groundwater regime. The approach involves geophysical, hydrogeological, hydro-chemical and aquifer modeling studies. The investigation has the significance as many habitats surround the mining area facing groundwater problems.

The Identity of "Chromium Malate".

Recently, several studies on the effects of a compound named "chromium malate," with the proposed formula "Cr2malate3·xH2O" where x = 3.5 or 5, on the health of healthy and diabetic rats have appeared. However, the compound is poorly characterized, and knowing the identity of this material could be important in the interpretation of the previous and of future studies on the effects of this compound in animals. Consequently, the synthesis, characterization, and identity of this material were explored. A combination of spectroscopic, magnetic, and elemental analyses and mass spectral studies reveal that the compound is probably a polymer, not a discrete molecule, and does not have the composition previously reported. The repeating unit of the polymer possesses an antiferromagnetically coupled trinuclear Cr(III) core. The current study suggests that previous reports on chromium malate and its effects in animals must be viewed with caution.

Localization and Speciation of Chromium in Coptis chinensis Franch. using Synchrotron Radiation X-ray Technology and Laser Ablation ICP-MS.

Coptis chinensis Franch. is one of the most important medicinal plants globally. However, this species contains relatively high concentrations of chromium (Cr) which potentially detrimental to human health. It is important to understand Cr localization and speciation in order to evaluate its accumulation and transportation mechanisms and minimize Cr transfer to humans. As little previous work in this area has been carried out, we utilized synchrotron radiation microscopic X-ray fluorescence (SR-µXRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to spatially locate Cr, X-ray absorption near-edge spectroscopy (XANES) to analyze Cr speciation, and inductively coupled plasma mass spectrometry (ICP-MS) to detect Cr subcellular concentration. Micromapping results showed that Cr was distributed predominantly within the vascular cylinder, the periderm and some outer cortex, and the cortex and some vascular bundles in root, rhizome, and petiole, respectively. XANES data showed that Cr(VI) can be reduced to Cr(III) when grown with Cr(VI), and yielded a novel conclusion that this plant contain elemental chromium. ICP-MS data showed that Cr was primarily compartmentalized in cell walls in all tissues. The new insights on Cr accumulation in C. chinensis Franch. provide a theoretical basis for the evaluation of Cr in other medicinal plants.

Evaluation of controlled-release devices for providing chromium sesquioxide and zinc in Huacaya alpacas at pasture.

OBJECTIVE: To assess the effectiveness of controlled-release devices (CRDs) for providing zinc and for estimating faecal output in alpacas and sheep at pasture. METHODS: The study groups of 10 alpacas and 10 sheep at pasture were paired within species and allocated at random to receive by mouth either one CRD containing chromium sesquioxide designed to function for at least 21 days or two CRDs, one containing chromium sesquioxide and the other zinc oxide designed to release over a nominal 60-day period. Faecal concentrations of chromium, zinc and ash, blood and plasma concentrations of zinc and plasma activity of alkaline phosphatase (ALP) were measured over a period of 117 days after treatment. RESULTS: The mean faecal chromium excretion profiles suggested that the CRDs performed in a similar manner in both species, releasing chromium for nearly 30 days in alpacas and for slightly more than 30 days in sheep. Using a common predetermined release rate of chromium from the CRDs, the daily faecal outputs of alpacas and sheep were estimated to be 0.54 kg dry matter and 0.33 kg dry matter, respectively. The CRD containing zinc oxide provided after 1 week an estimated daily release rate of 40 mg zinc with a lifetime of between 60 and 70 days in both species. The additional zinc did not elicit a response in blood zinc concentrations or in plasma ALP activity. CONCLUSION: The CRDs were retained in the gastrointestinal tracts of the alpacas and sheep and both types functioned as expected. The CRD delivering chromium sesquioxide at a known release rate provided an estimate of faecal dry matter output over a period of almost 3 weeks and the CRD formulated to deliver supplementary zinc did so at the nominal release rate over a period of approximately 60 days in both species. These data indicated that the standard sheep CRD is applicable for use in alpacas.

Minimization of the environmental impact of chrome tanning: a new process with high chrome exhaustion.

In all tanning technology operations wastes are generated. These reach the environment as residual waters, solid and liquid waste as well as atmospheric emissions and odours. This study tests an alternative method to the traditional tanning method at an industrial level. The new method is based on tanning without float and by significantly increasing the temperature at the end of the tanning process. The properties of the leathers obtained using the two methods have been compared and the results indicate that those leathers have similar physical, chemical, and organoleptic properties. However, the differences existing from the environmental point of view are significant. It is not necessary to use clean water for this tanning. Moreover, there is a 75% reduction of the residual float, a 91% reduction of the chrome discharged, and a 94% reduction of the chlorides discharged. A financial assessment was carried out to demonstrate that the newly proposed system is 32% more economic than the traditional one.

Extraction of chromium(III) and chromium(VI) species from solid matrices using green solvent supercritical carbon dioxide.

Supercritical fluid extraction (SFE) provides an environmentally green technique to decontaminate chromium species from solid matrices using supercritical fluid carbon dioxide (ScCO2). Methanol and a small amount of water were found to significantly improve the extraction efficiency. The fluorinated chelating agent lithium bis(trifluoroethyl)-dithiocarbamate (LiFDDC) was effective in removing Cr ions in methanol-modified CO2 via in situ chelation/SFE technique. This paper indicates that the extraction efficiencies of Cr(III) and Cr(VI) from solid matrices can be greatly increased to more than 92% in the presence of a small amount of water, using 5% methanol-modified CO2 containing LiFDDC as an extractant. Chromium species in a wood waste sample in the form of chromated copper arsenate (CCA) can be extracted, but the extraction efficiency is not as good as expected, possibly due to the complications of the chemistry of Cr species in different oxidation states and to matrix effects.

Biosorption of Cr(III) from aqueous solution using algal biomass spirogyra spp.

In the present investigation, a fresh water green algae spirogyra spp. was used as an inexpensive and efficient biosorbent for Cr(III) removal from aqueous solution. The algal biomass was treated with 0.1M NaOH, 0.2M CaCl(2) and 5% HCHO. The biosorption efficiency was compared with untreated biomass. The effects of various physico-chemical parameters were studied, e.g. pH 3.0-6.0, initial metal ions concentration 20-150mgL(-1), algal dose 1.0-3.0gL(-1), and contact time 15-180min, respectively. Biosorption of Cr(III) is highly pH dependent. Maximum 81.02% adsorption of Cr(III) was observed with 0.2M CaCl(2) treated biomass at pH 5.0. Removal of Cr(III) was more than 70% in 45min of contact time with different treated and untreated algal biomass at concentration 30mgL(-1). Maximum metal uptake (Q(max)) was observed as 30.21mgg(-1) with 0.2M CaCl(2) treated algal biomass indicate good biosorbents than other treated and untreated biomass. The high values of correlation coefficient (r(2)<0.90) indicate equilibrium data of treated and untreated form of algal biomass well fitted in Freundlich than Langmuir isotherms model equations.

Addition of chromic oxide to creep feed as a fecal marker for selection of creep feed-eating suckling pigs.

OBJECTIVE: To determine whether the addition of chromic oxide (Cr(2)O(3)) to creep feed could be used as a visual marker in feces for selection of creep feed-eating suckling pigs. ANIMALS: 20 suckling pigs. PROCEDURES: Via syringe, 5 pigs (2 to 3 days old on day 0; 1 pig/treatment) from each of 4 litters received oral administrations of 10, 20, 30, or 40 g of creep feed containing 10 g of Cr(2)O(3)*kg(1) on each of 2 consecutive days (days 20 and 21) or 30 g of creep feed containing 10 g of Cr(2)O(3)*kg(1) on day 20 and 30 g of Cr(2)O(3)-free creep feed on day 21. On days 21 through 24, 6 fecal samples were collected from each pig at regular intervals between 8:00 AM and 6:00 PM. Green-colored feces were considered indicative of creep feed consumption (eaters). Data analyses were based on single and multiple fecal samples. RESULTS: On day 22, evaluation of 1 fecal sample/pig and multiple fecal samples per pig resulted in identification of as many as 40% and only 15% of the feed-treated pigs wrongly as noneaters, respectively. Repeated sampling over multiple days would identify 99% of eaters accurately. Pigs erroneously identified as noneaters were those administered either low amounts of Cr(2)O(3)-supplemented creep feed for 2 days or Cr(2)O(3)-supplemented creep feed on only 1 day. CONCLUSIONS AND CLINICAL RELEVANCE: Data suggest that addition of Cr(2)O(3) to creep feed enables selection of individual creep feed-eating suckling pigs via examination of feces, provided that repeated fecal samples are evaluated.

Simultaneous determination and speciation analysis of arsenic and chromium in iron supplements used for iron-deficiency anemia treatment by HPLC-ICP-MS.

This work proposes the use of high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) for simultaneous speciation of arsenic and chromium in iron supplements used for the treatment of anemia. The sample preparation procedure recommended for the total determination of arsenic and chromium was established using acid digestion in a microwave assisted oven. For speciation analysis, however, the microwave-assisted extraction procedure involved the use of water as extraction solvent at 90°C for 30min. The chromatographic separation was performed using a mobile phase containing 1.0mM tetrabutylammonium hydroxide (TBAH), 0.7mM ethylenediaminetetraacetic acid (EDTA) and 5% methanol at pH 7.2. Helium was used in the collision cell for elimination of the interferences. Under optimized conditions, the separation and detection of the As(III), As(V), Cr(III) and Cr(VI) species can be performed in 5min, permitting their quantification with the external calibration technique with standards prepared in the mobile phase. The limits of quantification obtained were 0.008, 0.010, 0.5 and 0.14µgg-1, for As(III), As(V), Cr(III) and Cr(VI), respectively. The accuracy of the method was evaluated and confirmed by addition/recovery tests. The recoveries obtained varied from 81% to 110%. The proposed method was applied to the speciation analysis of arsenic and chromium in commercially available iron supplements acquired in several cities in Brazil and Spain. The content of the species ranged from 0.01 to 1.3µgg-1 for arsenic, and from 0.4 to 61.2µgg-1 for chromium.

[Surveillance of Chromium(VI) Concentrations in Mineral Water Products].

We developed and evaluated a method of quantifying chromium(VI) in mineral water (MW). After a performance evaluation, we performed a surveillance of chromium(VI) concentrations in 150 kinds of MW products purchased from markets in 2016. Recovery rates, as examined by using 150 spiked samples prepared from the purchased MW products, ranged from 93 to 107%. These results strongly suggest that the validated method is suitable for quantifying chromium(VI) in MW. Chromium(VI) was detected in 65 kinds of MW products; the detection rate was 43%. The minimum concentration of chromium(VI) was 0.0001 mg/L and the maximum was 0.0019 mg/L. The median value of chromium(VI) concentration was 0.0003 mg/L. In most of the products in which chromium(VI) was detected, the concentration ranged from 0.0001 to 0.0002 mg/L. No products were found with concentrations higher than the value (0.05 mg/L) set by the Food Sanitation Law as the specification for MW.

Leaching behavior of Cr(III) in stabilized/solidified soil.

The leaching behavior of chromium was studied using batch leaching tests, surface complexation modeling and X-ray absorption near edge structure (XANES) spectroscopy. A contaminated soil sample containing 1330 mg-Cr kg(-1) and 25600 mg-Fe kg(-1) of dry soil was stabilized/solidified (S/S) with 10% cement, 25% cement, 10% lime and a mixture of 20% flyash and 5% lime. The XANES analysis showed that Cr(III) was the only Cr species in untreated soil and S/S-treated samples. The leachate Cr concentration determined using the toxicity characteristic leaching procedure (TCLP) was reduced from 5.18 mg l(-1) for untreated soil to 0.84 mg l(-1) for the sample treated with 25% cement. The Cr leachability in untreated and treated soil samples decreased dramatically as the pH increased from 3 to 5, remained at similar levels in the pH range between 5 and 10.5, and further decreased at pH>10.5. Modeling results indicated that the release of Cr(III) was controlled by adsorption on iron oxides at pH<10.5, and by precipitation of Ca(2)Cr(2)O(5).6H(2)O at pH>10.5.