Detection and Analysis of 12 Heavy Metals in Blood and Hair Sample from a General Population of Pearl River Delta Area

To detect the content of 12 heavy metals in blood and hair sample from a general population of Pearl River Delta area, and to analyze the influence of duration of residence, gender, age, smoking and drinking on the heavy metal content. Use inductively coupled plasma mass spectrometry to detect the content of 12 heavy metals lead (Pb), mercury (Hg), cadmium (Cd), aluminum (Al), arsenic (As), copper (Cu), chrome (Cr), manganese (Mn), nickel (Ni), zinc (Zn), tin (Sn) and antimony (Sb) in blood and hair samples of a total of 50 subjects from a general population, collected by multistage stratified cluster random sampling method. The geometric mean of heavy metal content in blood samples of general population (μg/L): blood aluminum 214.00; blood chrome 92.82; blood manganese 21.43; blood nickel 20.59; blood copper 0.67; blood zinc 11.50; blood arsenic 0.55; blood cadmium 2.45; blood tin 0.00; blood antimony 1.92; blood lead 158.84; and blood mercury 1.19. The geometric mean of heavy metal content in hair samples of general population (μg/g): hair aluminum is 84.65; hair chrome 0.00; hair manganese 2.44; hair nickel 0.61; hair copper 28.49; hair zinc 136.65; hair arsenic 0.75; hair cadmium 0.46; hair tin 1.04; hair antimony 0.05; hair lead 8.97; and hair mercury 0.69. Some heavy metals were correlated with duration of residence, gender, age, smoking and drinking. This was the first time that simultaneously detecting heavy metal content in blood and hair was used to analyze the internal heavy metal burden in resident population of Pearl River Delta area. These data can serve as reference for further research.     

Toxic metals in freshwater fish from the Zagreb area as indicators of environmental pollution

The aim of this investigation was to determine the levels of heavy metals and metalloids in freshwater fish from the Zagreb area. A total of 216 freshwater fish samples from 5 sites were examined: Sava river upstream from Zagreb, Sava river at Zagreb, Sava river downstream from Zagreb, Jarun Lake, and 5 "ecologic" fishponds from the Zagreb surroundings. The metals lead, cadmium, mercury and the metalloid arsenic were determined by the method of atomic absorption spectrometry. The mean pooled levels of lead, cadmium and arsenic in all fish samples were 112.3 +/- 95 micrograms/kg, 8.5 +/- 11 micrograms/kg and 23.5 +/- 36 micrograms/kg, and did not exceed the allowed levels of 1,000 mg/kg, 100 micrograms/kg and 200 micrograms/kg, respectively. In 4 fish samples, the levels of mercury exceeded the allowed limit of 500 micrograms/kg (509, 596, 605 and 788 micrograms/kg), however, the pooled mean level of mercury was 127.8 +/- 90 micrograms/kg. There was no major difference in the levels of heavy metals between the two fish families observed, although the levels of lead, cadmium and mercury were higher in the family Ictaluridae (144 vs. 107 micrograms/kg, 10.4 vs. 8.2 micrograms/kg, and 153 vs. 124 micrograms/kg, respectively), whereas the level of arsenic was higher in the family Cyprinidae (23.8 vs. 21.8 micrograms/kg). Although the Sava river at Zagreb is the main recipient of sewage and wastewater in the Republic of Croatia, the levels of heavy metals were within the allowed limits in all groups of freshwater fish samples, with the exception of 4 samples that contained moderately elevated levels of mercury. Study results suggest that only mercury could be considered a good indicator of environmental pollution, because higher levels of mercury were measured in the fish from the Sava river than in the fish from the Jarun Lake and fishponds from the Zagreb surroundings, considering both pooleded and fish family specified data.     

上海市食用菌重金属污染状况的研究

本文通过对上海不同区域的金针菇、蘑菇、平菇、鸡腿菇及香菇5种常见鲜食用菌进行实地抽样,采用微波消解前处理,电感耦合等离子体质谱法(ICP-MS)测定食用菌中铅(Pb)、砷(As)、汞(Hg)、镉(Cd)的含量,考察鲜食用菌的重金属污染状况.研究结果表明,不同食用菌中重金属的污染状况随其种类和地域的不同而呈现显著差异.As、Pb、Cd和Hg在食用菌中的平均含量分别为0.177 mg/kg、0.094 mg/kg、0.082 mg/kg和0.004 mg/kg,均低于GB 2762-2012《食品安全国家标准食品中污染物限量》中的限量标准,说明上海市售鲜食用菌的重金属含量总体上是安全的.但在这5种食用菌中,部分蘑菇样品中的砷残留存在安全风险,样品超标率为27.3%;但进一步研究表明,超标蘑菇样品中无机砷占总砷的比例仅为4.4%~6.3%,最高含量仅为0.370 mg/kg,以无机砷含量替代总砷含量进行考察,则这些样品也是食用安全的.虽然在不同地区的食用菌中,这4种重金属的含量有显著差异,但均低于国标限定值,说明在上海市不同地区出售的食用菌总体上是安全的,可以放心食用.     

Dietary Intake of Metals by the Population of Tarragona County (Catalonia,Spain): Results from a Duplicate Diet Study

The daily intakes of arsenic (As), beryllium, cadmium (Cd), cobalt, chromium, copper, mercury (Hg), manganese, nickel, lead (Pb), antimony, tin, thallium, uranium, vanadium, and zinc by an adult population living in Tarragona County (Catalonia, Spain) were determined by the duplicate diet method with a 10-day sampling period. Duplicate diet samples, prepared as per consumption, were collected during September 2010 in 20 restaurants offering a variety of daily menus (breakfast, lunch, and dinner). A total of 200 composite samples, corresponding to 600 individual samples, were prepared for trace elements analyses, which were carried out by inductively coupled plasma mass spectrometry. The results were compared with data from previous total diet studies (TDS) recently performed in the same geographical area. Notable differences in the intake of the toxic elements As, Cd, Hg, and Pb were found depending on the method used. It is concluded that both the duplicate diet method and the TDS may provide important and useful information to estimate human exposure to metals through the diet and their derived health risks. However, for comparison between surveys or for establishing temporal trends in the intake of metals, it seems to be recommendable to use always the same method. Notwithstanding, if the interest is only to know whether the intake of a certain element is below the tolerable intake, both methods are useful.     

Metals and arsenic in marine fish commercialized in the NE Brazil: Risk to human health

Abstract

Arsenic, cadmium, lead, and mercury in fish is the result of long-term biomagnification in the food chain and is of public concern, due to the toxicity they engender. The objective of this research was to determine the concentrations of arsenic, cadmium, lead, and mercury in 13 species of marine fish broadly commercialized in Aracaju, SE, Brazil and to evaluate the risks of fish consumption associated with these trace elements, using the Target Hazard Quotient (THQ). As, Cd, and Pb levels were measured with inductively coupled plasma mass spectrometry (ICP-MS), and mercury was analyzed via cold vapor atomic absorption spectrometry. The results indicate a large variability in concentrations for arsenic (0.07–2.03?mg kg^–1) and mercury (0.01–1.44?mg kg^–1), associated with the animal dietary category. Cadmium (0.04–0.19?mg kg^–1) and lead (<0.01–0.45?mg kg^–1), on the other hand showed a mild variability. None of the evaluated specimens had As, Cd, and Pb THQ values higher than 1. The THQ values for mercury were higher but indicated no consumption risk, except for amberjack, and snook fish. Overall THQ indicates lower risk of consumption in fish that are at the base of the food chain, than in those that are top predators.     

Towards prenatal biomonitoring in North Carolina: assessing arsenic, cadmium, mercury, and lead levels in pregnant women

Exposure to toxic metals during the prenatal period carries the potential for adverse developmental effects to the fetus, yet such exposure remains largely unmonitored in the United States. The aim of this study was to assess maternal exposure to four toxic metals (arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb)) in a cohort of pregnant women in North Carolina. We analyzed blood samples submitted to the North Carolina Department of Health and Human Services for blood typing to assess toxic metal levels in pregnant women (n = 211) across six North Carolina counties. Whole blood metal concentrations were measured by inductively coupled plasma mass spectrometry. The association between maternal characteristics, including county of residence, age, and race, and metal exposure was analyzed using multiple linear regression analysis. A large fraction of the blood samples showed detectable levels for each of the four metals. Specifically, As (65.7%), Cd (57.3%), Hg (63.8%), and Pb (100%) were detected in blood samples. Moreover, compared with adult females participating in the Fourth National Report on Human Exposure to Environmental Chemicals and guidelines for pregnant women, some women in the sample population exceeded benchmark levels of Cd, Hg, and Pb. Evidence from this pilot study indicates that pregnant women in North Carolina are exposed to As, Cd, Hg, and Pb and suggests that factors related to maternal county of residence and race may impact maternal exposure levels. As increased levels of one or more of these metals in utero have been associated with detrimental developmental and reproductive outcomes, further study is clearly warranted to establish the impacts to newborns.     

Heavy metal and arsenic accumulating fern species as potential ecological indicators in As-contaminated abandoned mines

Ferns are good ecological indicators of arsenic accumulation in contaminated abandoned mines. The rhizomes of ferns were analyzed for arsenic and other heavy metals using inductively coupled plasma-mass spectrometry. In addition, we examined the ribulose-bisphosphate carboxylase (rbcL) gene isolated from the indigenous species of ferns at the pithead, tailings and soil sites in the vicinity of the Myoungbong abandoned mine, Republic of Korea. A search of the GenBank database revealed that the predicted amino acid sequence of this gene was homologous with 99% of Pteridium aquilinum As-2 (EU476184), 99% of Deparia petersenii As-6 (EU476188), 97% of Deparia lobatocrenata As-8 (EU476190), and 98% of Deparia conilii As-7 (EU476189). High concentrations of heavy metals (arsenic, 17.6 mg/kg in rhizomes and 2690 mg/kg in soil; copper, 17.1 mg/kg in rhizomes and 40.7 mg/kg in soil; cadmium, 2.9 mg/kg in rhizomes and 12.2 mg/kg in soil; lead, 41.9 mg/kg in rhizomes and 135 mg/kg in soil; zinc, 27.0 mg/kg in rhizomes and 172 mg/kg in soil) were found in P. aquilinum As-2 (EU476184) from the Myoungbong mine area, which may play an important role as ecological indicators of the contaminated areas.     

大肠杆菌拓扑异构酶I结合重金属的特性及功能影响

【背景】大肠杆菌拓扑异构酶Ⅰ(Escherichia coli topoisomerase I,E.coli TopA)在DNA复制、转录、重组和基因表达调控等过程发挥关键作用。研究表明E.coli TopA只有结合锌离子才具有活性,然而E.coli TopA能否结合其他金属离子尤其是重金属离子,以及结合其他金属后是否具有活性,目前仍不清楚。【目的】探究大肠杆菌拓扑异构酶Ⅰ是否结合环境中常见重金属离子,研究重金属离子结合E.coli TopA蛋白后对其活性的影响。【方法】在分别添加有锌、钴、镍、镉、铁、汞、砷、铬、铅、铜离子的M9基础培养中表达、纯化出E.coli TopA蛋白,并对纯化得到的蛋白用电感耦合等离子体质谱仪进行相应金属离子含量的测定;利用表达E.coli TopA锌指结构的突变体蛋白鉴定重金属离子的结合位点;通过体外超螺旋DNA松弛实验测定不同金属结合E.coli TopA的拓扑异构酶活性;通过测定蛋白内源性荧光推测不同金属结合E.coli TopA的空间构象差异。【结果】E.coli TopA在体内除了能结合锌和铁之外,还能够结合钴、镍、镉3种离子,但是不能结合汞、砷、铬、铅、铜离子。钴、镍、镉结合形式的E.coli TopA,每个蛋白分子最多可以结合3个相应的金属离子,他们与TopA蛋白的结合位点也是位于3个锌指结构域,而且每个锌指结构域结合1个金属离子。此外,E.coli TopA结合钴、镍、镉离子后,其DNA拓扑异构酶活性并未受到影响,可能是由于钴、镍、镉离子结合形式的E.coli TopA蛋白,其空间构象与锌结合形式相比并未发生显著变化。【结论】由于DNA拓扑异构酶在维持细胞正常生理功能中发挥关键作用,研究表明E.coli TopA的功能不会受到常见重金属的干扰(不结合或者结合后活性无影响),这也有可能是大肠杆菌在进化过程中产生的对抗环境中重金属离子毒害作用的一种自我保护和耐受机制,具有重要的生理意义。     

四种重金属在金针菇栽培过程中的迁移规律

为了掌握铅、镉、砷、汞4种有害重金属元素在金针菇栽培过程中的富集和迁移,为金针菇产品质量控制提供依据。采用在培养料中添加一定量的铅、镉、汞、砷栽培金针菇,测定其在各栽培阶段培养料、金针菇子实体中的含量。结果表明,在试验的浓度范围内,金针菇子实体中4种重金属的含量随着培养料中添加量的增加而增加,说明金针菇子实体中4种重金属主要是来源于培养料,但金针菇子实体对不同重金属的吸收富集能力不同,对汞的吸收富集能力最强,富集系数最高达到7.590,富集能力大小依次为汞>镉>砷>铅。     

长江经济带典型锌冶炼园区不同固废处置模式生态效率研究

我国铜铅锌有色冶炼固废种类多、存量大,富含多种环境毒害元素如镉铬汞砷等,而目前固废末端处置方式单一,对其所含的大量铜铅锌银镍等有价金属组分也未能有效分离,固废污染防控与高效资源化利用问题突出,已成为制约产业绿色可持续发展的关键因素。以长江经济带典型铜铅锌综合冶炼基地为例,设置直接处理(情景1)、内部循环(情景2)和协同利用(情景3)三种锌冶炼固废处置情景模式,结合物质投入产出法、层次分析法与熵值法,构建资源能耗、环境风险、物质循环与经济效益的多维生态效率指标核算方法体系,对三种情景模式开展生态效率综合评估分析。结果表明,情景3因加强了锌冶炼固废在铜、铅冶炼系统间的协同转化,其生态效率综合评价指数最高,为0.2246,较情景1和情景2分别高出313.6%和25.5%;从资源能耗角度来看,情景2单位产品能耗最高,达0.3086;而从物质循环和经济效益角度来看,情景3固废综合利用率最高,达97.6%,铜铅锌三种有价金属回收率达97.2%,利润总额达48131.3万元;但在环境风险方面,尽管情景3固废中重金属污染排放减少1470.4 t/a,但废气中铅砷镉汞等重金属污染排放却比情景1增加了3倍...     

Analytical methods for heavy metals in herbal medicines

Introduction – It is estimated that about 70–80% of the world's population relies on non‐conventional medicine, mainly of herbal origin. However, owing to the nature and sources of herbal medicines, they are sometimes contaminated with toxic heavy metals such as lead, arsenic, mercury and cadmium, which impose serious health risks to consumers. It is critical to analyse source materials for heavy metals in order to ensure that their concentrations meet the related standards or regulations limiting their concentrations in herbal medicines. In this review, different analytical methods for analysis of heavy metals in herbal medicines are discussed. Objective – To provide a comprehensive review of the current state of the art in analytical methods used to detect heavy metals in herbal medicines. Methodology – We systematically searched and reviewed the research articles regarding analytical methods for heavy metals in herbal medicine from various databases, such as Medline/PubMed, ScienceDirect, SciFinder, Google Scholar, EBSCO, Gale InfoTrac, Ingenta, Ovid, ProQuest and ISI Web of Knowledge. Results – In this review, we discuss in detail several commonly used and sensitive analytical techniques, including atomic absorption spectrometry, inductively coupled plasma optical emission spectrometry or mass spectrometry, X‐ray fluorescence spectrometry, high‐performance liquid chromatography, differential pulse polarography, neutron activation analysis and anodic stripping voltammetry. We also provide some application examples of these analytical techniques for heavy metals in herbal medicines. Copyright © 2011 John Wiley & Sons, Ltd.     

Chitosan-Zn Chelate Downregulates TLR4-NF-κB Signal Pathway of Inflammatory Response and Cell Death-Associated Proteins Compared to Inorganic Zinc

The object of this study is to analyze the levels of seven toxic elements residues in raw bovine milk in China and assess the potential health risk of those residues. The 178 raw bovine milk samples were collected from eight main milk-producing provinces and from three types of milk stations in China, and were analyzed for arsenic (As), lead (Pb), cadmium (Cd), chromium (Cr), mercury (Hg), aluminum (Al), and nickel (Ni) using inductively coupled plasma-mass spectrometry (ICP-MS). Al, Pb, Hg, Ni, Cr, and As were detected in 47.8, 29.2, 28.1, 23.6, 12.4, and 9.0% of total milk samples, respectively, and Cd were not detected in all samples. The raw bovine milk samples with high levels of toxic elements were found in industrial areas, such as Heilongjiang and Shanxi. Nemerow pollution index analysis showed that the levels were lower in the samples from the processing plants than that from the large-scale farms and small farm cooperatives. The margin of exposure (MOE) values suggest that the levels of As, Pb, Hg, Cr, Al, and Ni in the raw milk samples are not causing a health risk for Chinese consumers, including adults and children. Nevertheless, the risk of Pb for infant and young children was more serious than adult.     

Levels of Heavy Metals and Trace Elements in Umbilical Cord Blood and the Risk of Adverse Pregnancy Outcomes: a Population-Based Study

To better understand the relationship between prenatal exposure to heavy metals and trace elements and the risk of adverse pregnancy outcomes, we investigated the status of heavy metals and trace elements level in a Chinese population by collecting umbilical cord blood. Umbilical cord blood heavy metals and trace elements concentrations were determined by inductively coupled plasma–mass spectrometry. No differences with statistical significance in the median arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), strontium (Sr), thallium (Tl), vanadium (V), and zinc (Zn) concentrations were observed between the adverse pregnancy outcome group and the reference group. Titanium (Ti) and antimony (Sb) were found at higher levels with statistical significance in the cord blood samples with adverse pregnancy group when compared to the ones in the reference group. The association between Ti levels and the risk of adverse pregnancy outcomes remained significant after adjusting for potential confounding factors, including newborn weight. These results indicated that environmental exposure to Ti may increase the risk of adverse pregnancy outcomes in Chinese women without occupational exposure.     

Distribution and health risk assessment of heavy metals in soil surrounding a lead and zinc smelting plant in Zanjan,Iran

One of the problematic issues in soil pollution studies is heavy metal particles which are produced by mines and smelting units and spread through wind action and/or runoff. Pollution and health risk assessment of cadmium, lead, zinc, copper, and nickel in soil around the lead and zinc smelting factory was carried out in Zanjan City, Iran. Contamination factor (Cf), pollution load index (PLI), geoaccumulation index (Igeo), hazard quotient (HQ), hazard index (HI), and carcinogenic risk were pollution and human health risk assessment metrics in this study. Based on the Iranian soil guideline value, soil samples in the studied areas were contaminated the least by copper and nickel and the most by cadmium. PLI results showed that soils near the production line were heavily or extremely heavily polluted. The results of Cf and Igeo showed that lead and zinc were the most important contaminants. Health risk assessment indicated that lead and cadmium in soil were the main contaminants, which pose both carcinogenic and non-carcinogenic risks to human health; carcinogenic risk levels were unacceptably high (above 1 × 10^?4). It can be concluded that mining and smelting activities degrade soil quality in this region and the soil pollution might be extended to farming areas.     

Hair Toxic Element Content in Adult Men and Women in Relation to Body Mass Index

The primary objective of the current study was to estimate the hair toxic metal content in adults in relation to body mass index. A total of 1,229 persons including 719 women and 510 men were examined. All subjects were divided into two age groups: 1 and 2 periods of adulthood. All men and women were also subdivided into groups in relation to their values of body mass index (BMI): underweight, normal weight, overweight and obese. Hair aluminium (Al), beryllium (Be), cadmium (Cd), mercury (Hg), lead (Pb) and tin (Sn) content was evaluated using mass spectrometry with inductively coupled plasma. It has been shown that increase in body weight is accompanied by elevated hair cadmium content in women. At the same time, no significant alteration of hair cadmium concentration was observed in males. Higher values of scalp hair mercury and lead content were observed in men and women with increased body mass index independently of their age. BMI-related elevation of hair tin content was registered only in men of the first period of adulthood. A significant correlation between hair metal content and the values of BMI was observed for mercury independently of the gender of the subjects, whereas BMI values correlated significantly with hair cadmium levels in women and lead and tin levels in men. It has been also estimated that hair cadmium, mercury and lead levels in men exceed the respective values in women.     

黔西北土法炼锌废弃地植被重建的限制因子

以土法炼锌废弃地的废渣、污染土壤和背景土壤为基质材料,分别种植黑麦草(Lolium perenne)和三叶草(Trifolium pretense),分析各种基质的基本化学特性、重金属(Pb、Zn、Cd)含量及其赋存形态、两种植物生长特性.结果表明,土法炼锌废渣上植被重建的主要限制因子包括高盐碱胁迫、有机质含量低、养分缺乏(TN、碱解N、TK).废渣重金属含量高,有效态含量低,对植物毒性小,但存在潜在危害性.污染土壤重金属含量低于废渣,但生物有效态重金属含量高.污染土壤植被重建的限制因子包括重金属毒性、P和K的有效性.废渣与污染土壤混合是土法炼锌废弃地基质改良的有效途径.     

Report on the levels of cadmium, lead, and mercury in imported rice grain samples

In an attempt to know whether highly consumed food might contribute to metal exposure, we analyzed cadmium, lead, and mercury in 27 rice grain samples commonly consumed in Saudi Arabia by atomic absorption spectrometry after acid digestion. The mean concentrations and ranges of cadmium, lead, and mercury in tested rice samples were 20.261 (range <DL-178.026 μg/kg), 134.819 (range 23.1–1529.0 μg/kg), and 3.186 (range <DL-43.573 μg/kg), respectively. The results showed high concentrations of metals and in some cases exceeded the Provisional Tolerance Weekly Intake (PTWI) recommended by FAO/WHO. It was also noted that different rice grain samples had varying concentrations of these metals. Because the bulk of literature warns against the cumulative effects of prolonged heavy metal exposure, regular consumption of rice by local populations might pose potential health problems.     

压力罐消解ICP-MS法同时测定全血中5种微量元素

为了建立同时测定全血中微量元素铬、锰、砷、镉、铅的电感耦合等离子体质谱(ICP-MS)分析法,采用压力罐消解技术对全血样品进行消化,使用ICP-MS法对全血中的五种微量元素铬、锰、砷、镉、铅含量进行测定。结果显示,全血样品中所测定的5种微量元素浓度为0~0.20μg·mL-1时,线性关系良好,相关系数r>0.999,各元素相对标准偏差(RSD)均小于5.0%(n=6),加标回收率为88.4%~107.6%,本法对铬、锰、砷、镉、铅的最低检出浓度分别为0.60、1.4、0.70、0.048、0.18μg·L-1。表明运用ICP-MS同时检测全血中微量元素具有良好的准确度和精密度、灵敏度高、检出限低、元素之间的干扰少,方法高效可行。     

Distribution of heavy metals and arsenic in soils and indigenous plants near an iron ore mine in northwest Iran

Heavy metal contaminations in the environment of mining area have become a global problem. The vicinity of an iron ore mine was investigated to estimate the concentrations of As, Pb, Cd, Mn, Ni, Zn, and Cr in the soil and the feasibility of using native plants for phytoremediation. For this, concentrations of elements in soil samples collected and were analyzed by inductivity coupled plasma optical emission spectrometry. The concentrations of heavy metals and arsenic in the roots and aerial parts of Dactylis glomerata L. and Scleranthus orientalis Rössler were analyzed by inductively coupled plasma mass spectrometer too. As concentrations in the samples surpassed the soil toxicity threshold. Cd concentration in soil samples was considerably high next to mine pit. Neither species was identified as a hyperaccumulator, but both species could be considered as excluder plants for As.     

Comparison of the toxicity and distribution of cadmium and lead in plant cells

Summary. The toxicity of heavy metals (Cd, Zn, and Pb) was assessed by in vivo observations of their effect on cytoplasmic streaming in Allium cepa L. bulb scale epidermal cells. On the basis of our results, the order of toxicity of the studied cations is Zn < Pb ≪ Cd. The difference in toxicity between cadmium and lead was found to be very large. When cytoplasmic streaming was assessed, this difference was threefold. When the total content of cadmium and lead (determined by inductively coupled plasma mass spectrometry) was the criterion, the difference in toxicity was 15-fold. Fractionation of the tissue and enzymatic digestion of the cells revealed that the largest proportion of cadmium was located in the cell walls (56%), whereas almost all of the lead (97.6%) was accumulated in an insoluble form. The speciation of water-soluble Pb and Cd fractions is discussed on the basis of analysis by capillary zone electrophoresis interfaced with inductively coupled plasma mass spectrometry of water extracts from epidermal cells. Lead and cadmium appeared to be bound mainly to salts, which explains their toxicity. Cadmium was complexed (detoxified) by organic acids, while thiols were the metal-complexing species for lead. Histidine formed complexes with both cadmium and lead. Ultrastructural analyses showed that lead was encapsulated in small vesicles in the cytoplasm. Fluorescence studies of the endoplasmic reticulum (ER) revealed that it underwent extensive fragmentation under the influence of lead, with numerous ER vesicles appearing in the cells. In other words, the lead deposits in the cytoplasm were contained in vesicles arising from fragmentation of the ER. These observations indicate that epidermal cells have a rapid and effective mechanism for detoxifying lead involving the ER, and this may be one of the mechanisms accounting for the lower toxicity of lead in comparison with cadmium. The suitability of Allium cepa bulb scale epidermal cells for use in ecotoxicological studies is also discussed. Step-by-step directions for this test are given. Correspondence and reprints: Department of Ecotoxicology, Institute of Experimental Plant Biology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.