Detection of genotoxic effects of heavy metal contaminated soils with plant bioassays

Aim of the present study was the development of a bioassay which enables the detection of genotoxic effects of heavy metal contaminated soils. In the first part of the present study, the data base on metal effects in plant bioassays was extended. Four metal salts, namely Cr(VI)O3, Cr(III)Cl3, Ni(II)Cl2 and Sb(III)Cl3 were tested comparatively in MN tests with pollen tetrad cells of Tradescantia clone #4430 and in meristematic root tip cells of Vicia faba. With Cr6+ and Ni2+, clear-cut dose-effects were observed in a range between 0.75 and 10.0 mM, whereas this was not the case with Cr3+ (range tested 1.25-10 mM) and Sb3+ (range 0.30-5.25 mM). In Vicia, negative results were obtained with the four metal salts under all conditions of test. To compare the mutagenic potencies of the metals, the increases of the regression curves (k-values) were calculated, they indicate the number of MN induced per mM in 100 tetrad cells. The corresponding values for Cr6+ and Ni2+ are 0.87 and 1.05, respectively. It appears that the Tradescantia system is in particular sensitive towards those metal species which cause DNA damage in animals and man such as Cr6+, Cd2+, Ni2+, and Zn2+, whereas no clear positive results were obtained with less harmful metal ions such as Cu2+, Cr3+ or Sb3+. In the second part of the study, the mutagenic effects of four metal contaminated soils and two types of standardized leachates (pH 4.0 and pH 7.0) of these soils were tested in Tradescantia and in Vicia. In addition, chemical analyses were carried out to determine the metal concentrations in the soils and in the extracts. Two of the samples contained highly elevated levels of a number of metals (Zn, Pb, Cu, Cd, Sb, As), one soil came from the Central Austrian Alps and contained high As levels only. Direct exposure of the Tradescantia plants in the soils resulted in a drastic increase of the MN frequencies over the background. The lowest effect was seen with the Slovakian soil which contained in particular Sb and As (4.5-fold increase over the background), with the other soils, the induced frequencies were 11-15-fold over the control values. On the contrary, negative results were obtained upon exposure of Tradescantia cuttings in the leachates and upon implantation of germinated Vicia beans in the soils. The results of the present study indicate that Trad-MN assays with direct exposure of intact plants is an appropriate method which enables to detect genotoxic effects of metal contaminated soils in situ. This simple and fast biomonitoring assays might be a valuable supplement to analytical analyses of contaminated soils.

Evaluation of titanium dioxide as a digestibility marker for cattle

Three studies were conducted to evaluate titanium dioxide (TiO2) as a digestibility marker for cattle. In Exp. 1, eight steers consumed prairie hay ad libitum with or without dietary supplements. Fecal recovery of TiO2 averaged 93% and was not affected (P = 0.47) by supplement. Digestibilities calculated with reference to TiO2 were not different (P = 0.15) from those based on total fecal collections. In Exp. 2, two steers were limit-fed corn-based diets. Fecal recovery of TiO2 averaged 95% and that of chromic oxide (Cr2O3) averaged 113%. Digestibilities calculated with reference to TiO2 were underestimated (P < 0.01) by 1.1 percentage units relative to those based on total fecal collections, and those calculated with reference to Cr2O3 were overestimated (P < 0.01) by 2.0 percentage units. In Exp. 3, eight steers in a replicated 4 x 4 Latin square consumed corn-based diets ad libitum. Fecal recovery of TiO2 averaged 90%, whereas that of Cr2O3 averaged 98%. Digestibilities calculated with reference to TiO2 were underestimated (P < 0.01) by 1.6 to 4.3 percentage units, whereas those calculated with reference to Cr2O3 were not different (P = 0.31) from those based on total fecal collections. Future research is warranted to determine the usefulness of TiO2 in measuring digestibility in cattle.

Chromium in the environment: an evaluation of exposure of the UK general population and possible adverse health effects

Chromium in the hexavalent form, Cr(VI), has long been recognized as a carcinogen and there is concern as to the effects of continuous low-level exposure to chromium both occupationally and environmentally. This review summarizes the available exposure data and known health effects and evaluates the potential risk to human health in the United Kingdom. Chromium emissions to the environment in the United Kingdom are predominantly derived from fuel combustion, waste incineration, and industrial processes. The less toxic trivalent form of chromium [Cr(III)] is dominant in most environmental compartments, and any Cr(VI), the more toxic form, that is emitted to the environment can be reduced to Cr(III). Food is a major source of exposure to chromium, and estimated daily oral intakes for infants (1 yr), children (11 yr), and adults are 33-45, 123-171, and 246-343 micrograms/person/d, respectively. Soil ingestion, particularly common in young children, can contribute to oral intake. Inhalation is a minor route of exposure for the general population. Average daily inhalation intakes in infants can range from 0.004 microgram/d for rural infants to 0.14 microgram/d for urban infants who are passively exposed to tobacco smoke, whereas adults who live in industrialized areas and smoke may take up between 2 and 12 micrograms/d. The most serious health effect associated with Cr(VI) is lung cancer, which has been associated with some occupational exposure scenarios, whereas Cr(III) is an essential nutrient with a broad safety range and low toxicity. The human body has effective detoxification mechanisms that can reduce ingested or inhaled Cr(VI) to Cr(III). In conclusion, there is no clear evidence to relate exposure to environmental levels of chromium with adverse health effects in either the general UK population or subgroups exposed to chromium around industrialized or contaminated sites. It can be expected that an improved understanding of the relevance of possible long-term accumulation of Cr(III) in the body may facilitate a more complete assessment, in the future, of the health risks in the general population associated with environmental exposure to chromium.

Comparison of inert markers [chromic oxide or insoluble ash (Celite)] for determining apparent metabolizable energy of wheat- or barley-based broiler diets with or without enzymes

A broiler chick bioassay was used to measure the effect of two inert digestibility markers on the determination of dietary AME. Diets contained 80% of either wheat or barley (with or without enzyme) and either chromic oxide at 0.5% or one of three levels of insoluble ash (0.5, 1.0, or 1.5%) as markers. The various cereal and marker diet combinations were consumed ad libitum (0 to 21 d) by two groups of 10 male broilers in each of two trials. The AME of each diet was determined by measuring the respective marker ratios between diet and excreta (collected for 24 h at 7 or 21 d) or ileal digesta collected at 21 d. Growth and feed conversion were measured on each group of birds between 0 and 21 d. There was no effect of marker on growth or feed efficiency. However, determination of AME of wheat- or barley-based diets with or without enzymes were affected by choice of marker and whether markers were measured in excreta (7 or 21 d) or ileal digesta. Chromic oxide was viewed as the least accurate method for determining AME, based on chronic oxide's inability to define AME differences between barley-based diets with and without enzymes, whereas insoluble ash clearly demonstrated improved AME of wheat- and barley-based diets with an enzyme. The optimum levels of insoluble ash for accuracy and repeatability were between 0.5 and 1.0%. The AME of the diets were, on average, 5% lower when determined with 7 vs 21 d excreta and 2.5% lower for ileal digesta than excreta collected at 21 d. It was concluded that identification of components that result in variability in AME levels of diets will be improved if a bioassay uses insoluble ash as a marker.

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 (λ_ex = 365 nm), and the fluorescence could be effectively quenched by CrO₄^2- and Fe³⁺ ions. Meanwhile, the fluorescence of Tea-CDs-CrO₄^2- 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 CrO₄^2-, 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 CrO₄^2-, 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.

Gastrointestinal transit times in young and old cats

Ageing results in a decrease in apparent nutrient digestibility in the gastrointestinal (GI) tract. The aim of this study was to investigate whether the rate of gastric emptying or total GI transit times differed between young (3.0+/-0.9 years) and senior (11.6+/-1. 4 years) cats. Gastric emptying rates were measured using [1-(13)C]octanoic acid and total transit times with chromium oxide. No significant differences (P>0.05) were observed in either the rate of gastric emptying or total transit time between young and senior cats although senior cats exhibited a larger variability in total transit time compared to the younger cats (35.71+/-14.06 and 26. 46+/-5.80 h, respectively). The results of this study indicate that the observed reduction in nutrient digestibility in ageing cats is not due to alterations in the rate of passage of digesta through the GI tract.

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.

Emissions of air pollutants from household stoves: honeycomb coal versus coal cake

Domestic coal combustion can emit various air pollutants. In the present study, we measured emissions of particulate matter (PM) and gaseous pollutants from burning a specially formulated honeycomb coal (H-coal) and a coal cake (C-coal). Flue gas samples for PM2.5, PM coarse (PM2.5-10), and TSP were collected isokinetically using a cascade impactor; PM mass concentrations were determined gravimetrically. Concentrations of SO2, NOx, and ionic Cr(VI) in PM were analyzed using spectrometric methods. Fluoride concentrations were measured using a specific ion electrode method. PM elemental components were analyzed using an X-ray fluorescence technique. Total (gas and particle phase) benzo[a]pyrene (BaP) concentration was determined using an HPLC/fluorescence method. Elemental and organic carbon contents of PM were analyzed using a thermal/optical reflectance technique. The compositional and structural differences between the H-coal and C-coal resulted in different emission characteristics. In generating 1 MJ of delivered energy, the H-coal resulted in a significant reduction in emissions of SO2 (by 68%), NOx (by 47%), and TSP (by 56%) as compared to the C-coal, whereas the emissions of PM2.5 and total BaP from the H-coal combustion were 2-3-fold higher, indicating that improvements are needed to further reduce emissions of these pollutants in developing future honeycomb coals. Although the H-coal and the C-coal had similar emission factors for gas-phase fluoride, the H-coal had a particle-phase fluoride emission factor that was only half that of the C-coal. The H-coal had lower energy-based emissions of all the measured toxic elements in TSP but higher emissions of Cd and Ni in PM2.5.

Development of an ileal amino acid digestibility assay for the growing chicken--effects of time after feeding and site of sampling

1. The study aimed to establish the optimum time after ingestion and optimum sampling site for the development of an ileal amino acid digestibility assay for broiler chickens. 2. To establish the optimal sampling time, 4-week-old broiler chickens were given one of 6 protein sources (meat-and-bone, soyabean, cottonseed, fish, maize and wheat meals) as the sole source of protein in a test diet. The diets contained chromic oxide as an indigestible marker. The birds were starved for 24 h, fed and subsequently killed for sampling of ileal digesta (terminal 15 cm) at 2, 3, 4, 5 and 6 h after the start of feeding. 3. For the soyabean, fish, wheat and maize meal diets, sampling time had no significant effect on apparent ileal nitrogen digestibility, whereas for the meat-and-bone and cottonseed meal diets there was a significant quadratic effect of sampling time. The amount of digesta collected was maximised and the mean apparent ileal nitrogen digestibility had the lowest variation around the 4 h sampling time. 4. To establish the optimum sampling site, 4-week-old chickens were given either a meat-and-bone, a soyabean or a wheat bran meal-based diet. The birds were killed 4 h after the start of feeding, and digesta were sampled from 0-10, 0-15, 0-20 or 0-25 cm of terminal ileum. 5. There was no significant effect of sampling site on the apparent ileal digestibility of dietary nitrogen. The terminal 15 cm of ileum was considered a preferred site for sampling ileal digesta from broiler chickens.

Note on the methods for determination of chromic oxide in shrimp feeds

Chromic oxide is used as an inert marker to measure apparent digestibility of feeds in insects, terrestrial, and aquatic animals. Quantitative determination of chromic oxide content in the sample requires the oxidation of water insoluble trivalent chromic oxide to its water-soluble hexavalent form. The two commonly used oxidizing agents are 70% perchloric acid or a mixture of sodium molybdate, sulfuric, and perchloric acid. Chromic oxide content of the oxidized solution is then measured against known standards either directly by spectrophotometry in the visible range at 350, 370, or 440 nm or after forming a colored complex with diphenylcarbazide (DPC) by colorimetry at 540 nm. This study compared the two methods of oxidation followed by spectrophotometry at the three wavelengths and by DPC colorimetry. DPC colorimetry gave precise results than the direct measurement of dichromate ion, irrespective of the method of oxidation used. Ash from samples oxidized by perchloric acid and quantified by DPC colorimetry gave a better measure of actual chromic oxide content as compared to the other methods tested.

Release of Cr(III) from Cr(III) picolinate upon metabolic activation

Hexavalent and trivalent chromium are released into the environment from a number of different industrial activities. It is known that Cr(VI) can be reduced and subsequently complexed by humic acids to produce Cr(III) humic acid complexes in the soil and aquatic environments. The metabolic fate of Cr(III) humic acid complexes and other Cr(III) organic complexes in mammalian systems is unknown. Therefore, Cr(III) picolinate was chosen as a model complex for Cr(III) humic acid complexes and other environmentally relevant Cr(III) complexes. Both human hepatocyte microsomes and primary cultures of chick hepatocytes were used to generate metabolites of Cr(III) picolinate. The results from both of these treatments show that a significant amount of Cr(III) is released (66 and 100%, respectively) and that N-1-methylpicotinamide is the primary organic metabolite from this compound. These data suggest that the populations of humans who are exposed Cr(III) picolinate or other environmentally relevant organic Cr(III) complexes, such as Cr(III) humic acid complexes, are potentially accumulating high levels of Cr(III) intracellularly. This intracellular accumulation of Cr(III) can result in the formation of covalent bonds between Cr(III) and DNA and/or other macromolecules, causing genotoxic effects. These data should be considered when assessing the risk of an area contaminated with chromium.

Chromium transport, oxidation, and adsorption in manganese-coated sand

We examine how the processes of advection, dispersion, oxidation-reduction, and adsorption combine to affect the transport of chromium through columns packed with pyrolusite (beta-MnO2)-coated sand. We find that beta-MnO2 effectively oxidizes Cr(III) to Cr(VI) and that the extent of oxidation is sensitive to changes in pH, pore water velocity, and influent concentrations of Cr(III). Cr(III) oxidation rates, although initially high, decline well before the supply of beta-MnO2 is depleted, suggesting that a reaction product inhibits the conversion of Cr(III) to Cr(VI). Rate-limited reactions govern the weak adsorption of each chromium species, with Cr(III) adsorption varying directly with pH and Cr(VI) adsorption varying inversely with pH. The breakthrough data on chromium transport can be matched closely by calculations of a simple model that accounts for (1) advective-dispersive transport of Cr(III), Cr(VI), and dissolved oxygen, (2) first-order kinetics adsorption of the reduced and oxidized chromium species, and (3) nonlinear rate-limited oxidation of Cr(III) to Cr(VI). Our work supplements the limited database on the transport of redox-sensitive metals in porous media and provides a means for quantifying the coupled processes that contribute to this transport.

Endogenous recoveries and true ileal digestibilities of amino acids in newly weaned pigs fed diets with protease-treated soybean meal

Endogenous recoveries and true ileal digestibilities of amino acids were determined in pigs fed cornstarch-based diets with untreated or protease-treated soybean meal as protein sources. Twelve pigs, fitted with a modified post valve T-cecum cannula on d 14, 15, and 16 after birth, were weaned on d 20 and assigned to one of four diets according to a two-period balanced change-over design. Diets consisted of soybean meal 1) untreated (SBM), 2) incubated (1:2 wt/vol in distilled water adjusted to pH 4.5, for 16 h at 50 degrees C; CI-SBM), 3) sprayed with protease (1 microL/g of soybean meal; PS-SBM), and 4) incubated, as for CI-SBM, with protease in the water (PI-SBM) at the same application rate as that for PS-SBM. Each period consisted of 5 d of adaptation to diets followed by collection of ileal digesta on d 6 and 7 to determine the apparent ileal amino acid digestibilities of the diets. On d 9, guanidinated meals were fed, followed by a 24-h continuous collection of digesta. Recoveries of chromic oxide and dysprosium from the guanidinated meals were 96.0 +/- .5 and 94.5 +/- 1.1%, respectively. Endogenous amino acid recoveries were similar (P > .05) for SBM, CI-SBM, and PS-SBM but less (P < .05) for PI-SBM. True digestibilities were also less (P < .05) for PI-SBM than for the other meals. Recoveries of endogenous branched-chain and aromatic amino acids were less (P < .05) during Period 2 than during Period 1, suggesting dietary change- and(or) age-dependent adaptive increases in the secretions of pepsin and pancreatic proteases. In conclusion, protease treatment did not improve the true digestibilities of amino acids in soybean meal fed to newly weaned pigs.

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.

Recovery of 15N-lactoferrin is higher than that of 15N-casein in the small intestine of suckling, but not adult miniature pigs

Performance of biological functions of lactoferrin in the small intestine requires at least some resistance to degradation. Therefore, we studied prececal digestibility of lactoferrin in comparison to casein both in suckling and adult miniature pigs, applying 15N-labeled proteins. In study 1, 43 piglets (10-d-old), deprived of food for 12 h received 10 mL of sow's milk supplemented with 120 mg of 15N-labeled protein (porcine or bovine lactoferrin or bovine casein). Piglets were anesthetized 150 min later, after which the small intestine was excised, cut into three sections, and chyme was collected. In study 2, nine food-deprived boars fitted with T-canulae at the terminal ileum were given two semisynthetic experimental meals (204 g) in a cross-over design, 2 wk apart. One contained 7.5% (g/100 g) 15N-labeled bovine casein, the other 1.25% 15N-labeled bovine lactoferrin. Both were adjusted to 15% total protein with nonlabeled casein. Ileal chyme was collected from the canula over 33 h postprandially. All diets contained the indigestible marker chromic oxide. 15N-digestibility of lactoferrin, both porcine (84.4 +/- 3.2%) and bovine (82.3 +/- 4.8%), was significantly lower than casein digestibility (97.6 +/- 0.5%) in the distal small intestine of suckling piglets (P < 0.05). Based on immunoblotting after acrylamide electrophoresis, 4.5% of non- and partially digested lactoferrin was found in the last third of the small intestine of piglets. In adult miniature pigs there was no difference in 15N-digestibility of bovine lactoferrin compared to bovine casein (90.7 +/- 1.9% vs. 93.9 +/- 1.0%, P > 0.05). In suckling miniature pigs, the reduced digestibility of lactoferrin may provide the prerequisite for biological actions along the whole intestinal tract. The source of lactoferrin, porcine or bovine, made no difference in this respect.

The effect of dietary carbohydrates with different digestibility on the populations of Oesophagostomum dentatum in the intestinal tract of pigs

An experiment was undertaken to study the effect of dietary carbohydrates with different digestibility on the populations of Oesophagostomum dentatum in the intestinal tract of pigs. Sixty-four worm-free pigs from a specific pathogen-free farm were randomly divided into 8 equal groups. The animals in 4 groups were assigned to a diet with partially undegradable carbohydrates (diet 1), while the pigs in the 4 remaining groups were given a diet with fermentable carbohydrates (diet 2). Diet 1 was comprised of barley flour, oat husk meal, soybean meal, vitamins and minerals and diet 2 of barley flour, inulin and sugar beet fibre, soybean meal, vitamins and minerals. The pigs in 6 of the groups (n = 48) were inoculated with 6,000 infective larvae of O. dentatum. To determine O. dentatum populations at the early stage of infection, 16 pigs were slaughtered 3 weeks p.i., while the remaining 4 groups continued on the diets for a further 9 weeks after which they were slaughtered. In a diet cross-over experiment 6 weeks after inoculation, 8 pigs changed from diet 1 to diet 2 (diet 1 > diet 2), and 8 pigs from diet 2 to diet 1 (diet 2 > diet 1). The results showed that partially undegradable carbohydrates provided favourable conditions not only for parasite establishment and sustainability, but also for already established O. dentatum infection while, in contrast, the diet composed of highly degradable carbohydrates decreased worm establishment, size and female fecundity. The implications for pastured pigs or pigs fed different complex carbohydrate diets is discussed.

Effects of Supplemental Chromium Source and Concentration on Growth, Carcass Characteristics, and Serum Lipid Parameters of Broilers Reared Under Normal Conditions

An experiment was conducted to investigate the effects of dietary chromium (Cr) source and concentration on growth performance, carcass traits, and some serum lipid parameters of broilers under normal rearing conditions for 42 days. A total of 252 1-day-old Cobb 500 commercial female broilers were randomly allotted by body weight (BW) to one of six replicate cages (six broilers per cage) for each of seven treatments in a completely randomized design involved in a 2 × 3 factorial arrangement of treatments with three Cr sources (Cr propionate (CrPro), Cr picolinate (CrPic), Cr chloride (CrCl3)) and two concentrations of added Cr (0.4 and 2.0 mg of Cr/kg) plus a Cr-unsupplemented control diet. The results showed that dietary Cr supplementation tended to increase the breast muscle percentage compared with the Cr-unsupplemented control group (P = 0.0784), while Cr from CrPic tended to have higher breast muscle percentage compared with Cr from CrCl3 (P = 0.0881). Chromium from CrPic also tended to increase the breast intramuscular fat (IMF) compared with Cr from CrCl3 (P = 0.0648). In addition, supplementation of 0.4 mg/kg Cr tended to decrease low-density lipoprotein cholesterol (LDL-C) (P = 0.0614). Compared with the control group, broilers fed Cr-supplemented diets had higher triglyceride (TG) (P = 0.0129) regardless of Cr source and Cr concentration. Chromium from CrPro and CrPic had lower total cholesterol (TC) compared with Cr from CrCl3 (P = 0.0220). These results indicate that dietary supplementation of Cr has effects on carcass characteristics and serum lipid parameters of broilers under normal rearing conditions, while supplementation of organic Cr can improve carcass characteristics and reduce the cholesterol content in serum.

Respiratory health of workers exposed to low levels of chromium in stainless steel production

OBJECTIVES

To determine whether occupational exposure to chromite, trivalent chromium, or hexavalent chromium causes respiratory diseases, an excess of respiratory symptoms, a decrease in pulmonary function, or signs of pneumoconiosis among workers in an integrated chain of stainless steel production.

METHODS

This cross sectional study was carried out in 1993 and the inclusion criterion was a minimum of eight years of employment in the same production department. A self administered questionnaire was collected, and spirometry, measurement of diffusing capacity, chest radiography, and laboratory tests were carried out by a mobile research unit.

RESULTS

There were 221 workers in the exposure groups and 95 in the control group. The average duration of employment was 18 years. No significant differences in the odds ratios (ORs) of the symptoms were found between the exposure and the control groups. In a logistic regression analysis age and smoking significantly explained the occurrence of most of the respiratory symptoms. The smokers in the chromite group had significantly lower forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and diffusing capacity than the corresponding values of the control group. The analysis of variance between study groups, smoking, and exposure time, without modelling for interactions, showed that the chromite group had lower values for FVC, FEV1, and diffusing capacity than the other groups. The occurrence of small opacities was more frequent on the chest radiographs of the workers in the chromite group.

CONCLUSIONS

An average exposure time of 18 years in ferrochromium and stainless steel production and exposure to dusts containing low concentrations of hexavalent or trivalent chromium do not lead to any respiratory changes detectable by lung function tests or radiography nor to any increase in symptoms of respiratory diseases. The lung function values were lower and the occurrence of radiological findings was more frequent among the workers from the chromite mine than among the controls. The difference was partly caused by differences in age and smoking habits, but evidently also partly by higher exposures more than two decades ago or by the fibrous components of the dust.

Ecotoxicological risks associated with tannery effluent wastewater

The problem of water pollution acquires greater relevance in the context of a developing agrarian economy like Pakistan. Even though, the leather industry is a leading economic sector in Pakistan, there is an increasing environmental concern regarding tanneries because they produce large amounts of potentially toxic wastewater containing both trivalent and hexavalent chromium, which are equally hazardous for human population, aquaculture and agricultural activities in the area. Therefore, we defined the scope of the present study as to employ different bioassays to determine the eco-toxic potential of tannery effluent wastewater (TW) and its chromium based components, i.e., potassium dichromate (K(2)Cr(2)O(7)) and chromium sulfate Cr(2)(SO(4))(3). Particle-induced X-ray emission (PIXE) analysis of TW was carried out to determine the concentration of chromium in TW and then equal concentrations of hexavalent (K(2)Cr(2)O(7)) and trivalent chromium Cr(2)(SO(4))(3) were obtained for this study. Cytotoxicity assay, artemia bioassay and phytotoxicity assay was utilized to investigate the eco-toxicological potential of different concentrations of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3). All the dilutions of TW, K(2)Cr(2)O(7) and Cr(2)(SO(4))(3) presented concentration dependent cytotoxic effects in these assays. The data clearly represents that among all three tested materials, different dilutions of K(2)Cr(2)O(7) caused significantly more damage (P<0.001) to vero cell, brine shrimp and germination of maize seeds. Interestingly, the overall toxicity effects of TW treated groups were subsequent to K(2)Cr(2)O(7) treated group. Based on biological evidences presented in this article, it is concluded that hexavalent chromium (K(2)Cr(2)O(7)) and TW has got significant eco-damaging potential clearly elaborating that environmental burden in district Kasur is numerous and high levels of chromium is posing a considerable risk to the human population, aquaculture and agricultural industry that can obliterate ecosystem surrounding the tanneries.

The use of chromic oxide as a marker for measuring small intestinal digestibility in cannulated dogs

Small intestinal digestibility can be measured by comparing feed with effluent collected from an ileal T-cannula. Nevertheless, a nondigestible, nonabsorbable marker, such as chromic oxide (Cr2O3), must be included in the diet because simple T-cannulae do not divert chyme completely. This study was conducted to evaluate the excretion pattern of Cr2O3 in cannulated dogs because the kinetics of Cr2O3 has not been previously investigated in this nonruminant species. Chromic oxide was added to four diets fed to eight cannulated mixed-breed dogs in a Latin-square design. The four diets contained reciprocal proportions of protein from texturized vegetable protein (0% to 57%) and from beef (100% to 43%), so protein and carbohydrate digestibility varied among diets. All feces were collected during wk 2 and all ileal effluent during wk 3 of each diet period. Ileal recovery of Cr2O3 was almost complete (94%) and was greater than fecal recovery (87%) (P < or = .03). Recovery was not different among diet groups. Ileal DM digestibility was approximately 2 percentage units lower on d 1 (P < or = .007) than on d 2 to 4. Nevertheless, ileal DM digestibility varied little on these subsequent days so single-day collections should be accurate. Chromic oxide concentration in chyme varied widely during each collection but increased at the start and declined towards the end of each collection. Spot sampling may therefore result in inaccurate estimates of nutrient digestibility. In conclusion, Cr2O3 may be used as a marker to measure digestibility in dogs with simple T-cannulae, but total collections should be attempted for greater accuracy.

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.

A novel fluorescent distinguished probe for Cr (VI) in aqueous solution

Salicylaldehyde rhodamine B hydrazone (SRBH) was developed as a new spectrofluorimetric probe for the selective and sensitive detection of CrO(4)(2-) in acidic conditions. The proposed method was based on the special oxidation reaction between non-fluorescent SRBH by potassium dichromate to produce a highly fluorescent rhodamine B, as a product. Under the optimum conditions described, the fluorescence enhancement at 591 nm was good linearly related to the concentration of CrO(4)(2-) from 1.0 x 10(-8) to 3.0 x 10(-7)M (0.42-12.6 ng mL(-1)) with a correlation coefficient of R(2)=0.9989 (n=10) and a detection limit of 1.5 x 10(-9)M (0.063 ng mL(-1)). The relative standard deviation (R.S.D.) was 2.0% (n=6). The proposed method was also successfully applied to the determination of chromium (VI) in drinking water, river water and synthetic samples.

Water quality analysis of mixtures obtained from tannery waste effluents

In this study, the mixing of waste solution obtained from chrome tanning process and waste solution derived from liming of bovine leather was investigated. The liming process of bovine leather was performed using calcium carbonate and sodium sulfide, and the tanning process was performed using alkaline chromium sulfate. The analyses of waste solutions and sediments formed during the mixing process include pH values, the concentration of sulfides, the concentration of chromium(III) oxide, and parameters such as chemical oxygen demand and biochemical oxygen demand. All measurements were carried out before and after the mixing process. Results indicate that the mixing of the corresponding waste solutions yields the mixture effluents that are ecologically acceptable.

Environmental monitoring of chromium in air, soil, and water

Historical uses of chromium have resulted in its widespread release into the environment. In recent years, a significant amount of research has evaluated the impact of chromium on human health and the environment. Additionally, numerous analytical methods have been developed to identify and quantitate chromium in environmental media in response to various state and federal mandates such as CERCLA, RCRA, CWA, CAA, and SWDA. Due to the significant toxicity differences between trivalent [Cr(III)] and hexavalent [Cr(VI)] chromium, it is essential that chromium be quantified in these two distinct valence states to assess the potential risks to exposure to each in environmental media. Speciation is equally important because of their marked differences in environmental behavior. As the knowledge of risks associated with each valence state has grown and regulatory requirements have evolved, methods to accurately quantitate these species at ever-decreasing concentrations within environmental media have also evolved. This paper addresses the challenges of chromium species quantitation and some of the most relevant current methods used for environmental monitoring, including ASTM Method D5281 for air, SW-846 Methods 3060A, 7196A and 7199 for soils, sediments, and waste, and U.S. EPA Method 218.6 for water.

Tissue contents and subcellular distribution of chromium and other trace metals in experimental diabetic rats after intravenous injection of Cr 50-enriched stable isotopic tracer solution

In order to study the metabolism of essential trace elements in diabetics, we studied alloxan-diabetic rats for the distribution patterns of chromium (Cr), cobalt (Co), iron (Fe), selenium (Se), and zinc (Zn) in the liver, kidney, pancreas, and testes, as well as in the organ subcellular fractions. Normal rats were used as controls. Cr 50-enriched stable isotopic tracer solution was given by intravenous injection to avoid the difficulties of estimation of Cr status. Our data show that the concentrations of Zn in liver and kidney, of Co, Fe, and Zn in pancreas, and of Fe and Zn in testes of the diabetic rats were significantly higher than in the control rats. Nevertheless, the concentrations of Cr in pancreas, Fe in kidney, and Cr and Se in testes of the diabetic rats were significantly lower than in the controls. Furthermore, we observed significant alterations of element concentrations in subcellular fractions of various organs in the diabetic rats. These results suggest that changing hormone levels may interfere with the accumulation of some trace elements both in the organs and in the subcellular fractions of rats.