River water genotoxicity evaluation using micronucleus assay in fish erythrocytes

The quality of Caí river water (Rio Grande do Sul State) in an area under the influence of a petrochemical complex was studied using the micronucleus assay in erythrocytes from peripheral blood of the fathead minnow Pimephales promelas. This cytogenetic in vivo assay was performed to evaluate the effects of petrochemical effluents on the stream. Organisms were exposed to samples collected at four sites, during an 11-month period. Three different exposure periods were used (7, 14, and 21 days) to evaluate their influence in genotoxic detection. The 14-day exposure period was most effective in detecting genotoxicity in samples from this area. The presence of substances with clastogenic and/or aneugenic potential could be detected at the different sites analyzed. This in vivo assay allowed the detection of genotoxicity in the area studied, indicating the potential for environmental genotoxicity monitoring.     

Nephrotoxic and hepatotoxic effects of trivalent and hexavalent chromium in a teleost fish Anabas scandens: enzymological and biochemical changes.

The effects of trivalent and hexavalent chromium (Cr3+ and Cr6+) compounds on renal and hepatic respiratory enzymes and metabolites of a freshwater fish, Anabas scandens, were studied. In a subchronic exposure of 30 days, both forms of chromium inhibited the activities of lactate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, and isocitrate dehydrogenase, whereas the hexavalent form induced greater effects. The levels of pyruvate and lactate are not exactly reflected in lactate dehydrogenase activity.     

玉米种子对铬生态毒害检测的研究

目的探讨玉米种子对Cr3 和Cr6 的生态毒害检测的毒害浓度和适宜品种.方法选用3种玉米进行植物发芽毒性试验和根伸长试验,了解不同浓度Cr3 和Cr6 对3个品种玉米种子萌发、根生长及对玉米根尖细胞有丝分裂的影响.结果Cr3 和Cr6 在5×10-4 mol/L～1×10-2 mol/L浓度范围内对玉米的毒害作用随培养时间延长和浓度增加毒害加重.5×10-4 moL/L、1×10-3 mol/L浓度的铬对玉米的生长有轻微的刺激作用.结论两种价态的铬比较,Cr6 对3种玉米的毒害作用均大于Cr3 .1×10-2 moL/L为玉米耐受铬的最高浓度.3种玉米中农大108抗铬毒害能力最强.     

The effects of hexavalent and trivalent chromium on fertilization and development in sea urchins

The action of Cr⁶⁺ (as chromate) and Cr³⁺ (as sulfate and nitrate) on fertilization and development has been investigated in sea urchins. By rearing the embryos in the presence of chromate (5 × 10^?5 to 5 × 10^?4m), the differentiation of the gut and skeleton was severely affected. The treatment of sperm before fertilization with CrO^2?₄ (10 to 30 min, 10^?4 to 10^?2m) resulted in a number of abnormal larvae, depending on the length of exposure and the CrO^2?₄ concentration. Morphological and quantitative changes of mitotic activity during cleavage were observed as a result of CrO^2?₄ exposure of zygotes, as well as of sperm and egg pretreatment. The exposure of embryos to Cr³⁺ after fertilization permitted larval differentiation, but affected the motility and hatchability of the embryos. The pretreatment of gametes with Cr³⁺ never induced larval malformations. Cr³⁺ exerted a strong depressive action on fertilization by decreasing the fertilizing capacity of sperm and leaving the fertilizability of the eggs almost unaffected.     

Chromium bond detection in isolated erythrocytes: a new principle of biological monitoring of exposure to hexavalent chromium

Summary Internal stress to chromium is only relevant in occupational medicine if it is due to the handling of hexavalent chromium. Cr(VI) ions, after uptake by inhalation or percutaneously are carried in the blood plasma and penetrate—depending on the concentration—into the erythrocytes. Due to the intracellular reduction to Cr(III) and the concurrent intracellular protein binding, the erythrocytes represent an easily accessible target organ for quantitative chromium determination after occupational exposure to Cr(VI) compounds. The results of an earlier experimental study indicate that human plasma too is capable of spontaneous reduction of Cr(VI) ions of up to 2 ppm to Cr(III). This plasma reduction capacity (PRC) can be increased and accelerated considerably by adding ascorbic acid (AA). These findings were supported in this investigation by proving a decreased binding of Cr(VI) inside the erythrocytes under the effect of AA. This leads to the assumption that only those Cr(VI) concentrations can penetrate the membrane of the erythrocytes and enter the cell which either come into contact with the membrane during the reduction process or exceed this limit concentration of 2 ppm. Only in these two instances can corresponding chromium findings be analyzed in isolated and washed erythrocytes. These results are compared with those obtained by conventional methods, such as Cr determination in the blood and/or urine. Our findings indicate that a single determination of chromium concentration in the erythrocytes will permit the monitoring of critical cases of Cr(VI) exposure. This is a new type of biological monitoring in the sense of a condensed longitudinal study, in order to find out whether threshold concentrations have been respected over a given period.     

Determination of chromium picolinate and trace hexavalent chromium in multivitamins and supplements by HPLC-ICP-QQQ-MS

Chromium picolinate (CrPic) and trace hexavalent chromium (Cr(VI)) content were characterized in VITA-1 and VITB-1, two new multivitamin and mineral supplement candidate reference materials from National Research Council Canada, by two methods of high performance liquid chromatography inductively-coupled plasma triple quadrupole mass spectrometry. The conditions for the separation of Cr(VI) from EDTA-complexed Cr(III) were optimized such that species interconversions were not observed during analysis. Following extraction with dilute NH₄OH in water at pH 10 (for Cr(VI)) or 3:2 acetonitrile:water (for CrPic) and quantification by standard addition, it was concluded that CrPic accounted for 95–96 % of the Cr in VITA-1 and VITB-1, while Cr(VI) was not present above the detection limit of 0.13 μg Cr g⁻¹. Using the two developed methodologies, commercially-available nutritional supplements, in the form of vitamin tablets and dried food supplements, were assessed, and it was determined that CrPic accounted for the majority (92 %–98 %) of the chromium present in the tablets, and that Cr(VI) concentrations were below the detection limit for all samples except for the powdered beets where it accounted for nearly half of the total Cr present.     

Fume generation and content of total chromium and hexavalent chromium in flux-cored arc welding

This study was performed to investigate the fume generation rates (FGRs) and the concentrations of total chromium and hexavalent chromium when stainless steel was welded using flux-cored arc welding (FCAW) with CO2 gas. FGRs and concentrations of total chromium and hexavalent chromium were quantified using a method recommended by the American Welding Society, inductively coupled plasma-atomic emission spectroscopy (NIOSH Method 7300) and ion chromatography (modified NIOSH Method 7604), respectively. The amount of total fume generated was significantly related to the level of input power. The ranges of FGR were 189-344, 389-698 and 682-1157 mg/min at low, optimal and high input power, respectively. It was found that the FGRs increased with input power by an exponent of 1.19, and increased with current by an exponent of 1.75. The ranges of total chromium fume generation rate (FGRCr) were 3.83-8.27, 12.75-37.25 and 38.79-76.46 mg/min at low, optimal and high input power, respectively. The ranges of hexavalent chromium fume generation rate (FGRCr6+) were 0.46-2.89, 0.76-6.28 and 1.70-11.21 mg/min at low, optimal and high input power, respectively. Thus, hexavalent chromium, which is known to be a carcinogen, generated 1.9 (1.0-2.7) times and 3.7 (2.4-5.0) times as the input power increased from low to optimal and low to high, respectively. As a function of input power, the concentration of total chromium in the fume increased from 1.57-2.65 to 5.45-8.13% while the concentration of hexavalent chromium ranged from 0.15 to 1.08%. The soluble fraction of hexavalent chromium produced by FCAW was approximately 80-90% of total hexavalent chromium. The concentration of total chromium and the solubility of hexavalent chromium were similar to those reported from other studies of shielded metal arc welding fumes, and the concentration of hexavalent chromium was similar to that obtained for metal inert gas-welding fumes.     

Speciation of hexavalent chromium in welding fumes interference by air oxidation of chromium

The determination of various chromium species in welding fume normally involves digestion in a hot alkaline solution. This work confirms that Cr(III) can be oxidized to Cr(VI) during this digestion. However, only dissolved forms of Cr(III), such as the hydroxochromate(III) ion, [Cr(OH)4], are susceptible to oxidation under these conditions. The air oxidation of Cr(III) can be prevented by hydrolytic destabilization of the hydroxochromate(III) complex by the presence of magnesium hydroxide precipitate. The procedure has been used successfully in the determination of insoluble chromium(VI) in welding fumes. Excellent reproducibility is documented for soluble and insoluble chromium(VI) fractions in the analysis of a bulk sample of welding fume.     

一株除铬(Ⅵ)菌株的筛选和鉴定

目的 分离、驯化和鉴定高效除铬(Ⅵ)菌株。 方法 从某电镀厂聚集区域的环境中采集样品,接种逐步升高铬(Ⅵ)浓度的培养基分离筛选出耐铬(Ⅵ)菌株,通过比较各菌株的除铬(Ⅵ)能力筛选出高效除铬(Ⅵ)菌株,并采用革兰氏染色、生理生化实验、16S rDNA等技术进行菌种鉴定。 结果 菌株CQMU-1的除铬效果最好;CQMU-1为革兰氏阴性球菌或短杆菌;能在500mg/L的含铬(Ⅵ)LB肉汤中生长,但生长受抑制;其最适生长pH为7.0～8.0,温度为20～35℃,好氧,化能异养,能利用大多数碳水化合物;经16S rDNA鉴定CQMU-1为产碱菌属。 结论 筛选出1株高效除铬(Ⅵ)菌株,可用于去除环境中铬(Ⅵ)污染。     

Phytotoxicity and phytoaccumulation of trivalent and hexavalent chromium in brake fern

A recently recognized hyperaccumulator plant, Chinese brake fern (Pteris vittata), has been found to extract very high concentration of arsenic from arsenic-contaminated soil. Chromium usually is a coexisting contaminant with arsenic in most contaminated soils. The potential application of ferns for phytoremediation of chromium(III)- and chromium(VI)-contaminated soils and their phytotoxicity to ferns has not been studied before. In this study, chromium distribution and phytotoxicity at the plant and cellular levels of brake ferns were studied using chemical analyses and scanning electron microscopy. The results show a higher phytotoxicity of Cr from Cr(VI)-contaminated soil to Chinese brake fern than from Cr(III)-contaminated soil. Phytotoxicity symptoms included significant decreases both in fresh biomass weight and relative water content (RWC), and also in leaf chlorosis during the late stage of growing. At higher concentrations (500 mg/kg Cr[VI] and 1,000 mg/kg Cr[III] addition), plants showed reduction in the number of palisade and spongy parenchyma cells in leaves. Compared with other plant species reported for phytoremediation of Cr(VI)-contaminated soil, brake fern took up and accumulated significant amounts of Cr (up to 1,145 mg/kg in shoots and 5,717 mg/kg in roots) and did not die immediately from phytotoxicity. Our study suggests that Chinese brake fern is a potential candidate for phytoremediation of Cr(VI)-contaminated soils, even though plants showed severe phytotoxic symptoms at higher soil Cr concentrations.     

工作场所空气中六价铬的分离测定法

目的建立分离测定工作场所空气中六价铬化合物含量的方法。方法利用PVC尼龙6树脂在一定条件下能够分离三价铬、六价铬、富集六价铬的特性,同时结合石墨炉原子吸收法建立测定工作场所空气中六价铬化合物含量的方法。结果该方法中PVC尼龙6树脂对三价铬和六价铬的吸附率分别为4%和100%,六价铬的洗脱率超过96%,回收率范围为87.0%～108.0%,相对标准偏差为3.6%～7.9%,方法最低检出浓度为0.0033 mg/m~3。采集18组样本用国标法与该方法比较,测定值的差异无统计学意义(P>0.05)。结论该方法用于检测工作场所空气中六价铬化合物具有简单、准确、实用、抗干扰能力强等特点。     

Aqueous chemistry of airborne hexavalent chromium during sampling

Cr(III) is an essential micronutrient for the proper function of human being, while Cr(VI) is a carcinogenic chemical, which has been one of the hazardous air pollutants defined by US Environmental Protection Agency (US EPA) in 2004. Accurate measurements of atmospheric hexavalent chromium concentration are required to evaluate its toxicity. In the present study, a simulation tool using MATLAB program was developed to evaluate soluble and insoluble chromium species formed during the Cr(VI) field sampling (500 ml, 0.12 M HCO₃^? buffer, pH?=?9, 24 h, cellulose filter) which will assist us to better quantify the hexavalent chromium concentration. In this study, Cr(VI) was found to be dominant in soluble form as CrO₄^2? and in precipitated form as (NH₄)₂CrO₄, CaCrO₃, BaCrO₄, and PbCrO₄ at pH?=?9 cellulose filter. Secondly, reduction of Cr(VI) to Cr(III) was higher than the oxidation of Cr(III) to Cr(VI). Basic pH solutions retard the conversion of Cr(VI) in the presence of Fe(II) and As(III) and facilitate the precipitation of Cr(III). The presence of the NaHCO₃ as buffer on the cellulose filters and also in the filter extraction solution may add to the precipitation of Cr(VI) as NaCrO₄. This study provides new insights to improve cellulose sampling filters, and the filter extraction solutions to either prevent Cr(VI) precipitation during the wet analysis of Cr(VI) or improve the Cr(VI) analysis methods to quantify total Cr(VI) (soluble and insoluble Cr(VI)).     

Study of an analytical method for hexavalent chromium

The diphenylcarbazide colorimetric method was evaluated by analyzing spiked PVC filters prepared by an AIHA-accredited consultant laboratory for chromium (VI). All seven participating laboratories received the samples and performed the analyses at the same time. Three laboratories simultaneously tested three alternative analytical procedures. Reduced amounts of chromium (VI) were found by both the consultant and participating laboratories when using the test procedure and one of the alternative methods. Two of the alternative analytical methods, both of which involve an alkaline extraction procedure, provided higher recoveries and more precise values for the test filters. It appears that the alkaline extraction procedure may be more appropriate for occupational health samples taken in steel industry environments which may include several interferents. Suggestions are made for further studies to determine the most appropriate analytical method.     

离子色谱–质谱法测定水质中六价铬的方法研究

目的:建立离子色谱分离、电喷雾质谱检测水质中六价铬的方法。方法:水样经0.22μm微孔滤膜过滤后直接进样,以20 mmol/L KOH溶液为流动相,IonPac AS21 Analytical 2×250 mm色谱柱分离六价铬,使用单四级杆质谱,选择离子模式检测,监测离子为m/z118、117、101、85,其中117为定量离子。结果:Cr(Ⅵ)的线性范围为0μg/L～100.0μg/L,方法的检测限为0.57μg/L。在空白水样中分别添加4.0μg/L、10.0μg/L、50.0μg/L的六价铬,测得平均回收率(n=6)依次为102%、101%、100%,相对标准偏差分别为1.27%、2.82%、1.63%。与分光光度法对照表明,其结果无显著性差异。结论:该方法操作简便,快速,准确度和灵敏度高。     

Evaluation of genotoxicity of PCP and 2,4-D by micronucleus test in freshwater fish Channa punctatus

An in vivo study on the genotoxic effects of pentachlorophenol (PCP) and 2,4-dichlorophenoxyacetic acid (2,4-D) was carried out with freshwater air-breathing fish Channa punctatus. The fish were exposed to three sublethal doses of PCP (0.2, 0.4, and 0.6 ppm) and 2,4-D (25, 50, and 75 ppm) by medium treatment. Micronucleated erythrocytes were sampled at intervals of 48, 72, and 96 h post-treatment. Student's t test revealed significant increases in micronucleus (MN) frequency. Maximum incidence of MN was recorded at highest concentrations and durations for both chemicals. A time- and dose-dependent response of the MN frequency for both chemicals was confirmed. PCP-treated groups had 8-10 MN per cell, specifically at higher concentrations and duration. Echinocytes were recorded at higher concentrations of 2,4-D. The study confirmed the genotoxicity of PCP and 2,4-D in this organism. PCP was found to be more toxic than 2,4-D in terms of MN induction. This assay has further potential for detecting genotoxic compounds in aquatic ecosystems.