Establishing Causality between Exposure to Metals and Effects on Fish

This study evaluates causal relationships between chronic exposure of fish to metals and effects at different levels of biological organization based on a weight-of-evidence approach. Criteria for evaluation of causality were strength, consistency, and specificity of the association, as well as biological gradient and plausibility. Field sampling was conducted three times between 1998 and 2000, in Furnas Stream, impacted by an abandoned lead mine, and in three other locations, including two reference and one impacted sites. Levels of Pb, Zn, Cd, and Ag in sediments from the Furnas Stream exceeded background levels, and their concentrations were above sediment quality guidelines. Residual levels of metals in fish tissue were high enough to indicate reduced growth, reproduction and/or survival according to toxicological benchmarks. Lead-induced biochemical changes (ALA-D activity depletion) were observed in two species of siluriform catfish. The condition factor of a predatory catfish was reduced, and the percentage of prey generalists was higher in Furnas than at the noncontaminated sites. Reduction in fish community diversity and density was observed. Integration of data provided supporting evidence that observed effects on fish from the Furnas Stream resulted from long-term exposure to metals, however influences from other stressors cannot be ruled out.     

Evaluation of Potential Exposure to Metals in Laundered Shop Towels

We reported in 2003 that exposure to metals on laundered shop towels (LSTs) could exceed toxicity criteria. New data from LSTs used by workers in North America document the continued presence of metals in freshly laundered towels. We assessed potential exposure to metals based on concentrations of metals on the LSTs, estimates of LST usage by employees, and the transfer of metals from LST-to-hand, hand-to-mouth, and LST-to-lip, under average- or high-exposure scenarios. Exposure estimates were compared to toxicity criteria. Under an average-exposure scenario (excluding metals’ data outliers), exceedances of the California Environmental Protection Agency, U.S. Environmental Protection Agency, and the Agency for Toxic Substances and Disease Registry toxicity criteria may occur for aluminum, cadmium, cobalt, copper, iron, and lead. Calculated intakes for these metals were up to more than 400-fold higher (lead) than their respective toxicity criterion. For the high-exposure scenario, additional exceedances may occur, and high-exposure intakes were up to 1,170-fold higher (lead) than their respective toxicity criterion. A sensitivity analysis indicated that alternate plausible assumptions could increase or decrease the magnitude of exceedances, but were unlikely to eliminate certain exceedances, particularly for lead.     

Health Risk Assessment of Exposure to Metals in a Nigerian Water Supply

This article reports the health risk associated with chronic intake of metals in the municipal water supplies of Eleyele and neighboring towns in the Ibadan metropolitan area of Nigeria. A total of 42 composite samples, consisting of treated water from the water treatment facility and residential areas receiving personal-use water (i.e., tap water) directly from the facility, as well as raw water from the treatment facility's water supply dam were sampled twice every month for 7 months. Concentrations of the metals were determined by atomic absorption spectrophotometry. Among the metals studied, Cd, Co, Cr, and Pb were detected at concentrations higher than maximum regulatory limits. Cd, Co, Cr, and Pb concentrations in treated water at the treatment facility ranged from 0.08–0.10, 0.14–0.16, 0.04–0.22 and 0.07–0.36 mg L^?1, respectively, while personal-use water ranged from 0.08–0.11, 0.15–0.29, 0.02–0.29, and 0.12–0.65 mg L¹, respectively. Likewise, concentrations of the metals at the dam ranged from 0.06–0.08, 0.17–0.20, 0.13–0.37, and 0.03–0.15 mg L¹, respectively. It is estimated that exposure to the metals in the water supply results in oncological and non-oncological systemic health risks higher than is generally acceptable for drinking water.     

Sensory Perception: An Overlooked Target of Occupational Exposure to Metals

The effect of exposure to industrial metals on sensory perception of workers has received only modest interest from the medical community to date. Nevertheless, some experimental and epidemiological data exist showing that industrial metals can affect vision, hearing and olfactory function, and a similar effect is also suggested for touch and taste. In this review the main industrial metals involved are discussed. An important limit in available knowledge is that, to date, the number of chemicals studied is relatively small. Another is that the large majority of the studies have evaluated the effect of a single chemical on a single sense. As an example, we know that mercury can impair hearing, smell, taste, touch and also vision, but we have scant idea if, in the same worker, a relation exists between impairments in different senses, or if impairments are independent. Moreover, workers are frequently exposed to different chemicals; a few available results suggest that a co-exposure may have no effect, or result in both an increase and a decrease of the effect, as observed for hearing loss, but this aspect certainly deserves much more study. As a conclusion, exposure to industrial metals can affect sensory perception, but knowledge of this effect is yet incomplete, and is largely inadequate especially for an estimation of “safe” thresholds of exposure. These data support the desirability of further good quality studies in this field.     

Epigenetic Modifications Due to Heavy Metals Exposure in Children Living in Polluted Areas

The aim of the present article is to provide a summary of the epigenetic modifications that might occur in children exposed to heavy metals pollutants. It is known that children are more susceptible to environmental pollutants, because their detoxification enzymes are less competent, and this may lead to alterations in chromatin structure or of DNA causing, in turn, epigenetic modifications. Little is currently known about the long-term effects of these changes when occur early in childhood, none-theless there are ethics and practical concerns that make the assessment of DNA modifications difficult to perform in large-scale.     

Evaluating the Extent of LINE-1 Mobility Following Exposure to Heavy Metals in HepG2 Cells

The long interspersed elements-1 (LINE1 or L1 retrotransposon) constitute 17 % of the human genome and retain mobility properties within the genome. At present, 80–100 human L1 elements are thought to be active in the genome. The mobilization of these active elements may be influenced upon exposure to the heavy metals. In the present study, we evaluated the association of aluminum, lead, and copper exposure with L1 retrotransposition in human hepatocellular carcinoma (HepG2) cell line. An in vitro retrotransposition assay using an enhanced green fluorescent protein (EGFP)-tagged L1RP cassette was established to track EGFP shining as the mark of retrotransposition. Following determination of noncytotoxic concentrations of these metals, pL1RP-EGFP-transfected HepG2 cells were subjected to long-term treatment. Flow cytometry analysis of cells treated with various concentrations of these metals along with quantitative real-time PCR was used to quantify L1 retrotransposition frequencies. Aluminum significantly increased L1 retrotransposition frequency, while no significant association was found concerning lead exposure and L1 retrotransposition. Copper treatment downregulated L1 retrotransposition as a result of EGFP-tagged L1RP expression. Our findings suggest that aluminum might have the potential to cause genomic instability by the enhancement of L1 mobilization. Thus, the risk of induced L1 retrotransposition should be considered during drug safety evaluation and risk assessments of exposure to toxic environmental agents. Further studies are needed for a more robust assay to evaluate any associations between long-term lead exposure and L1 mobility in cell culture assay.     

Human Health Risks Derived from Dietary Exposure to Toxic Metals in Catalonia,Spain: Temporal Trend

The present study was aimed at estimating the current (2012) dietary intake of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) by the population of Catalonia, Spain. The temporal trends with respect to previous surveys, performed in 2000, 2005, and 2008, were also determined. For that purpose, metal concentrations were analyzed in a number of widely consumed foodstuffs. A speciation study was also conducted by experimentally determining the levels of inorganic As (InAs) and methylmercury (MeHg) in the same food items. Furthermore, the dietary intake of those metals and species was calculated both deterministically and probabilistically by considering two food consumption surveys: ENCAT and ENIDE, representative of the Catalan and Spanish populations, respectively. An important temporal decrease of the dietary intake was noted for most elements, irrespective of the age-gender population group. Considering data for a male adult, the current dietary intake of As, InAs, Cd, Hg, MeHg, and Pb was estimated in 216, 2.6, 8.7, 10, 7.3, and 8.4 μg/day, respectively, being these values lower than the respective provisional tolerable weekly intakes (PTWIs) or benchmark dose lower confidence limits (BMDLs). Moreover, new calculations by means of ENIDE survey indicated similar results to those previously obtained by ENCAT, with the exception of MeHg, whose intake exceeded the maximum recommended values for some part of the population. Although our data are similar to those frequently found in other European countries, the important intake of MeHg, which is linked to the high consumption of fish and shellfish, deserves further investigation.     

Association Between Chronic Exposure to Tobacco Smoke and Accumulation of Toxic Metals in Hair Among Pregnant Women

Tobacco smoke contains various toxic heavy metals that individuals are exposed to when they smoke. Despite the presence of heavy metals in tobacco smoke, the relationship between smoking and the accumulation of toxic metals in pregnant women after long-term exposure remains under discussion. We examined the association between long-term exposure to tobacco smoke and the accumulation of toxic metals in the hair of female participants. Our study recruited 252 women from the Shanxi and Hebei provinces of Northern China; these participants were self-reported non-active smokers, and had previously delivered healthy babies without birth defects. Scalp hair was collected and analyzed for nicotine and cotinine and five potentially toxic metals (specifically, silver, chromium, cadmium, mercury, and lead). Our results showed significant positive correlations between cotinine and four metals, including silver (r?=?0.369, p?<?0.001), cadmium (r?=?0.185, p?<?0.01), mercury (r?=?0.161, p?<?0.05), and lead (r?=?0.243, p?<?0.001). Significant positive correlations were also found between nicotine and three metals—specifically silver (r?=?0.331, p?<?0.001), cadmium (r?=?0.176, p?<?0.01), and lead (r?=?0.316, p?<?0.001). A logistic regression model showed significant associations between cotinine and potentially toxic metals including mercury, silver, and lead (with or without adjusting for potential confounders). We thus conclude that long-term passive smoking could potentially increase the exposure level of toxic metals including lead, silver, and mercury in our study, which are especially harmful for pregnant women and their unborn fetus.     

Human Exposure to Metals: Levels in Autopsy Tissues of Individuals Living Near a Hazardous Waste Incinerator

The concentrations of a number of metals were determined in the brain, bone, kidney, liver, and lung of 20 autopsied subjects who had lived, at least 10 years, in the neighborhood of a hazardous waste incinerator (HWI) in Tarragona (Catalonia, Spain). Results were compared with those obtained in 1998 (baseline survey) and previous surveys (2003 and 2007). Arsenic, Be, Ni, Tl, and V showed concentrations below the corresponding detection limits in all tissues. Cadmium showed the highest levels in the kidney, with a mean value of 21.15 μg/g. However, Cd was found below the detection limit in the brain and bone. Chromium showed similar concentrations in the kidney, brain, and lung (range of mean values, 0.57–0.66 μg/g) and higher in the bone (1.38 μg/g). In turn, Hg was below the detection limit in all tissues with the exception of the kidney, where the mean concentration was 0.15 μg/g (range, <0.05–0.58 μg/g). On the other hand, Mn could be detected in all tissues showing the highest levels in the liver and kidney (1.45 and 1.09 μg/g, respectively). Moreover, Pb showed the highest concentrations in bone (mean, 1.39 μg/g; range, <0.025–4.88 μg/g). Finally, Sn could be detected only in some tissue samples, reaching the highest values in the bone (0.17 μg/g). The current metal levels in human tissues from individuals living near the HWI of Tarragona are comparable and of a similar magnitude to previously reported results corresponding to general populations, as well as those of our previous surveys.     

Comparison of Physiological Changes in Euglena gracilis During Exposure to Heavy Metals of Heterotrophic and Autotrophic Cells

The effect of different concentrations of Hg²⁺, Cd²⁺, and Pb²⁺ on ultrastructure, growth, respiration, photosynthesis, chlorophyll content, and metal accumulation in Euglena gracilis was examined. The toxicity of the heavy metals was dependent on the culture medium used and whether cells were grown in the dark or under illumination. Hg²⁺ was the most toxic metal, which showed effects at a concentration as low as 1.5 μM; Cd²⁺ showed an intermediate toxicity (effects observed above 50 μM); and Pb²⁺ was almost ineffective up to 1 mM. Cells grown for several weeks in the dark, in the presence of 1.5 μM Hg²⁺ showed a reduced sensitivity to subsequent exposure to Cd²⁺ or Pb²⁺. The Hg²⁺-pretreated cells also presented an enhanced capacity to accumulate other metals. In comparison, light-grown cells showed a greater Cd²⁺ accumulation, but a lower Pb²⁺ uptake than Hg²⁺-pretreated dark-grown cells. Pretreatment of light-grown cells with Hg²⁺ did not enhance the accumulation of Cd²⁺. These results suggest that the capacity to tolerate heavy metals by Euglena may have mechanistic differences when cells are grown in the dark or under illumination.     

Lack of Complete Exposure Pathways for Metals in Natural and FGD Gypsum

Use of wallboard made from synthetic gypsum generated via flue-gas desulfurization (FGD) by coal-fired power plants (FGD gypsum) raised questions concerning the potential for exposure to residual trace metals. Because gypsum is widely used (e.g., in wallboard), any issue with metals could have far-reaching implications. A conceptual site model evaluated potential human health exposure pathways for metals in gypsum, through consideration of data for 21 metals including samples of natural (mined) gypsum, and of FGD gypsum. Because there are no screening values for gypsum, comparisons were made to background soil concentrations and to risk-based concentrations for metals in soil termed preliminary remedial action goals (PRGs), which assume more frequent and prolonged contact with particulate soil than would be likely for gypsum, and thus provide a health protective means for evaluation of exposure. Additional screenings evaluated occupational exposure and agricultural use of gypsum. Maximum metal concentrations in natural and FGD gypsum samples were either consistent with background concentrations or much lower than PRGs for residential or agricultural soil, or workplace air, and thus exposure pathways for these media were considered incomplete. Separate analyses of mercury volatilization were conducted, and this pathway was also found to be incomplete.     

Human Health Risk Assessment for Environmental Exposure to Metals in the Catalan Stretch of the Ebro River,Spain

The aim of this study was to investigate the environmental impact and the human health risks associated with metals exposure in the Catalan stretch of the Ebro River, Spain. The concentrations of the following elements were determined in soils and tap water: As, Cd, Cr, Cu, Hg, Mn, Ni, and Pb. Carcinogenic and non-carcinogenic risks were separately assessed for adults and children. Relatively low metal concentrations in tap water were found. It indicates that water intake is not a relevant source of metals for human health impact in the area under evaluation. In turn, the levels of metals in soils were similar or less than those found in a number of recent worldwide surveys. The presence of industrial facilities located upstream the Ebro River, including a chloralkali plant, should not mean additional non-carcinogenic risks for the population living in the area. The results of the current study allow us to establish that the concentrations of most carcinogenic elements (with the exception of As) should not mean potential health risks for the local population. However, because of the relatively high levels of geological origin found for As, a continued monitoring of these elements would be desirable.     

Dietary Exposure to Metals by Individuals Living Near a Hazardous Waste Incinerator in Catalonia, Spain: Temporal Trend

The concentrations of arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), tin (Sn), thallium (Tl), and vanadium (V) were determined in a number of foodstuffs purchased during 2006 in various localities of Tarragona County (Catalonia, Spain), near a hazardous waste incinerator, which has been operating since 1999. The dietary intake of the above elements by the population of the area was subsequently estimated. The results were compared with those obtained in previous surveys (baseline 1997 and 2002) performed in the same area. The levels of Be, Tl, and V were under their respective limits of detection in all samples. The estimated dietary intakes of the elements analyzed in the current survey by an adult man of 70 kg were the following: 351?μg/day for As, 4.6?μg/day for Cd, 57.5?μg/day for Cr, 7.1?μg/day for Hg, 2,229?μg/day for Mn, 78.0?μg/day for Ni, 39.9?μg/day for Pb, and 37.9?μg/day for Sn. On average, fish and seafood were the main contributor to the total dietary intake of As, Cd, and Hg and one of the most important for Pb. In general terms, the differences on metal exposure through dietary intake between the present and our two previous surveys were not particularly relevant. The current intake of the most toxic elements (As, Cd, Hg, and Pb) remains under the respective Provisional Tolerable Weekly Intakes established by the Food and Agriculture Organization/World Health Organization.     

The Influence of the Occupational Exposure to Heavy Metals and Tobacco Smoke on the Selected Oxidative Stress Markers in Smelters

The aim of the study was to verify if there is any association between exposure to Cu, Zn, Cd, Pb, As and the formation of malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), advanced oxidation protein products (AOPP), and whether in this process cigarette smoking plays a role. The investigations were performed in the 352 smelters occupationally exposed to heavy metals and 73 persons of control group. Metals concentration was determined by atomic absorption spectrometry. MDA and AOPP concentrations were determined by spectrophotometric methods. The concentration of 8-OHdG was determined by ELISA method. It was demonstrated an increased Cu concentration in smoking smelters compared to non-smoking control group. It was noted no differences in Zn and Mg concentrations between the examined groups. Pb concentration was more than sixfold higher in the group of smoking smelters and about fivefold higher in the group of non-smoking smelters compared to the control groups (smokers and non-smokers). It was shown that Cd concentration in the blood was nearly fivefold higher in the smoking control group compared to the non-smoking control group and more than threefold higher in the group of smoking smelters compared to non-smoking. It was shown an increased As concentration (more than fourfold) and decreased Ca concentration in both groups of smelters compared to control groups. In groups of smelters (smokers and non-smokers), twofold higher MDA and AOPP concentrations, and AOPP/albumin index compared to control groups (smokers and non-smokers) were shown. Tobacco smoke is the major source of Cd in the blood of smelters. Occupational exposure causes accumulation of Pb in the blood. Occupational exposure to heavy metals causes raise of MDA concentration and causes greater increase in AOPP concentration than tobacco smoke.     

Acute Toxicity,Respiratory Reaction,and Sensitivity of Three Cyprinid Fish Species Caused by Exposure to Four Heavy Metals

Using 3 cyprinid fish species zebra fish, rare minnow, and juvenile grass carp, we conducted assays of lethal reaction and ventilatory response to analyze sensitivity of the fish to 4 heavy metals. Our results showed that the 96 h LC₅₀ of Hg²⁺ to zebra fish, juvenile grass carp, and rare minnow were 0.14 mg L⁻¹, 0.23 mg L⁻¹, and 0.10 mg L⁻¹, respectively; of Cu²⁺0.17 mg L⁻¹, 0.09 mg L⁻¹, and 0.12 mg L⁻¹ respectively; of Cd²⁺6.5 mg L⁻¹, 18.47 mg L⁻¹, 5.36 mg L⁻¹, respectively; and of Zn²⁺44.48 mg L⁻¹, 31.37 mg L⁻¹, and 12.74 mg L⁻¹, respectively. Under a 1-h exposure, the ventilatory response to the different heavy metals varied. Ventilatory frequency (Vf) and amplitude (Va) increased in zebra fish, juvenile grass carp, and rare minnows exposed to Hg²⁺ and Cu²⁺ (P<0.05), and the Vf and Va of the 3 species rose initially and then declined when exposed to Cd²⁺. Zn²⁺ had markedly different toxic effects than the other heavy metals, whose Vf and Va gradually decreased with increasing exposure concentration (P<0.05). The rare minnow was the most highly susceptible of the 3 fish species to the heavy metals, with threshold effect concentrations (TEC) of 0.019 mg L⁻¹, 0.046 mg L⁻¹, 2.142 mg L⁻¹, and 0.633 mg L⁻¹ for Hg²⁺, Cu²⁺, Cd²⁺, and Zn²⁺, respectively. Therefore, it is feasible to use ventilatory parameters as a biomarker for evaluating the pollution toxicity of metals and to recognize early warning signs by using rare minnows as a sensor.