High Concentrations Of As Research Articles

Street dust from a heavily-populated and industrialized city: Evaluation of spatial distribution, origins, pollution, ecological risks and human health repercussions

Emissions from vehicles include particles from tire and brake wearing that can settle down and join industrial discharges into street dust. Metals present in street dust may create ecological and health threats and their analysis is of great environmental relevance. The city of Monterrey, Mexico is an industrial pillar of the country and shows an increasing fleet during the last years, which has yielded higher traffic and emissions. This study analyzes 44 street dust samples taken across the city for total element concentrations by using X-ray fluorescence. Associations and indicators are calculated to define possible origins, levels of pollution, natural or anthropogenic sources, and ecological and human health risks. High concentrations of As, Ba, Cu, Fe, Mo, Ni, Pb, Ti, and Zn were found. Main sources of metals were defined as: tire wearing for Zn and Fe; brake wearing for Ba, Cu, Fe, Pb and Zr; additional industrial sources for Mo, Ni, Pb, and Ti; and other natural sources for As. Ecological risk was found to be moderate across the city and risk due to Pb concentrations was established for children.

Potentially toxic elements in agricultural soils from the Lombardia region of northern Italy

The aim of this survey was to assess the concentration range of potentially toxic elements (PTE) in agricultural soils of the Lombardia plain and to consider their spatial variability across the catchments of the Ticino, Adda, Oglio, Mincio and Po rivers. Agricultural soils were sampled at depths of 0–30 cm based on the LUCAS (Land Use/Cover Area frame statistical Survey) using a pre-existing network of geo-referenced points. The samples from each catchment were analysed to determine their main properties and their concentrations of As, Be, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Tl, V and Zn. The spatial distribution of PTEs reflected the predominant lithology on which the soils developed and the sediment deposition along the river catchments. The highest concentrations of As and Sb in the Adda basin and of Co, Cr and Ni in the Po basin were due to their geological origin. The elevated concentrations of Hg and Pb in the Adda basin probably arose from old mining operations. Italian legislation includes two legislative levels: A for residential/recreational areas and B for commercial/industrial areas. The A levels were exceeded only for As, Be, Co, Cr, Cu, Ni and Zn. The percentage of soils exceeding this threshold was low and consistently below 15% of the measured samples for all elements.

Characterizing the environmental impact of metals in construction and demolition waste.

Large quantities of construction and demolition (C&D) waste are generated in China every year, but their potential environmental impacts on the surrounding areas are rarely assessed. This study focuses on metals contained in C&D waste, characterizing the metal concentrations and their related environmental risks. C&D waste samples were collected in Shenzhen City, China, from building demolition sites, renovation areas undergoing refurbishment, landfill sites, and recycling companies (all located in Shenzhen city) that produce recycled aggregate, in order to identify pollution levels of the metals As, Cd, Cr, Cu, Pb, Ni, and Zn. The results showed that (1) the metal concentrations in most demolition and renovation waste samples were below the soil environmental quality standard for agricultural purposes (SQ-Agr.) in China; (2) Cd, Cu, and Zn led to relatively higher environmental risks than other metals, especially for Zn (DM5 tile sample, 360mg/kg; R4 tile sample, 281mg/kg); (3) non-inert C&D waste such as wall insulation and foamed plastic had high concentrations of As and Cd, so that these materials required special attention for sound waste management; and (4) C&D waste collected from landfill sites had higher concentrations of Cd and Cu than did waste collected from demolition and refurbishment sites.

Chemical speciation and bioavailability concentration of arsenic and heavy metals in sediment and soil cores in estuarine ecosystem, Vietnam

The first investigation of arsenic (As) contamination in soil cores in the biggest estuarine ecosystem in northern Vietnam was conducted using FE-EPMA, ICP-MS and XRD techniques. Concentrations of arsenic and five heavy metals were measured and mineralogical characteristic of soils and sediments in different land uses were analyzed. Most of the soils contained high proportions of As and heavy metals in the potential mobility fractions and silicate minerals. High concentrations of As and heavy metals were observed in river sediments and top-layers of mangrove forest soil cores. Qualitative analyses using WDS technique on FE-EPMA found As on the iron (hydro)oxides and framboidal pyrite surfaces in the samples. The principal component analysis indicated the enrichment of As and heavy metals in the upper soil layers, suggesting that intensive human activities in upstream of the Red river in recent decades could be the cause of elevated levels of these toxic elements in the estuarine ecosystem.

Сульфидная минерализация, самородное золото и его геохимические связи в рифейских отложениях Авзянского рудного района (Южный Урал)

In the Avzyan ore-bearing region the sulfides from the low-sulfide gold-quartz deposits (Ulyuk-Bar, Kurgashly) are characterized by higher concentrations of As, Co, Ni, Cu, Pb in comparison with sulfides from sediments outside of ore-bearing zones. The gold is associated with As and sometimes - with S and Co. Gold-bearing sulfides are situated mostly in sandstones, where they were formed as a result of replacement of early formed ore-free pyrites by arsenopyrite and its association with arsenic pyrite during fluid movement ( Т = 250-450°С, Р = 26-360 bar) through fault zones. This process is fixed in the zonal distribution of arsenic pyrite and in varying behavior of total As in rocks. The proportion of p-type conduction pyrite increases with the depth, and zones of its development and high content of As in rocks are controlled by faults. The strong positive correlation of Au with S, Cu, Co, Pb, Ni, Zn is marked at the gold-sulfide (Bogryashka) and gold-sulfide-quartz (Gorny Priisk) occurrences. The connection of Au with As is not clear. At the Bogryashka occurrence pyrites are characterized by high concentrations of Sb, at the Vostochno-Aktashskoe occurrence - by Co and V. The gold in the Gorny Priisk ore deposit and in the Bogryashka occurrence is characterized by high ratio Au/Ag (>21) and impurity of Bi (0.4-1.2 wt %). The ratio Au/Ag is 5-8 in the gold from the Ulyuk-Bar and the Vostochno-Aktashskoe occurrences. Native gold in the Ulyuk-Bar and the Bogryashka occurences is associated with uranium-thorium minerals.

Cadmium and arsenic bioaccumulation and bio-concentration in the endemic toothed carp Aphanius arakensis in salt water

Heavy metals are released to aquatic ecosystems from natural and anthropogenic recourses and accumulate to the body of organisms. This study aimed to assess the accumulation of As and Cd in the gill, liver, and muscle of the toothed carp Aphanius arakensis in salt water exposed to three concentrations of Cd and As (5, 10 and 20 mg L -1 ) for 18 days. The specimens were collected from the Shoor River with an average weight of 1.5±0.3 g (mean±SD) and length of 3.4±0.4 cm. The findings showed that the bio-concentration factor (BCF) of Cd and As were in the following order: liver > gill > muscle, however, for 5 ppm of As the order was gill > liver > muscle. BCF in As concentrations were more than Cd concentrations. Also, the highest BCF was found at 5 ppm. The present study showed that the liver is the organ that accumulates the highest concentrations of As and Cd.

Elementos traza en fertilizantes y abonos utilizados en agricultura orgánica y convencional


 
 
 Los fertilizantes y abonos son las principales fuentes de nutrientes de los cultivos. La composición de elementos traza en ellos ha sido poco estudiada en México, así como su ingreso total a los suelos por esta vía. Arsénico (As), cadmio (Cd), mercurio (Hg) y plomo (Pb) fueron determinados por espectrofotometría de masas con plasma acoplado inductivamente (ICP-MS) en nueve fuentes nutrimentales utilizadas en agroecosistemas orgánicos y convencionales; lombricomposta, composta, nitrato chileno, roca fosfórica, urea, nitrato de calcio, fosfato diamónico (DAP), superfosfato triple (SPT) y sulfato de potasio. Los resultados muestran que DAP, SPT, roca fosfórica y lombricomposta poseen las más altas concentraciones de As, Cd y Pb, mientras que Hg sólo fue detectado en SPT a bajas concentraciones. La urea, nitrato de calcio y sulfato de potasio obtuvieron las concentraciones más bajas. Sin embargo, la lombricomposta es el material que más elementos traza incorpora al suelo cuando se toma como fuente de 100 kg de N ha-1, las cantidades estimadas fueron 17139, 2190 y 76176 mg ha-1 deAs, Cd y Pb, respectivamente. En caso de usarse como fuente de P2O5 ó K2O, el ingreso al suelo de elementos traza será aún más alto.
 
 

Effects of mine tailing and mixed contamination on metals, trace elements accumulation and histopathology of the chub (Squalius cephalus) tissues: Evidence from three differently contaminated sites in Serbia

Chub (Squalius cephalus) specimens were collected in Korenita River seven months after spillover from the waste water of antimony mine tailing pond and compared with chub living in Kruščica reservoir (intended for water supply) and Međuvršje reservoir (influenced by intense emission of industrial, urban and rural wastewater). Concentrations of 15 elements (Al, As, B, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Si, Sr, Zn) were determined in muscle, liver and gills of chub by inductively coupled plasma optical spectrometry (ICP-OES) and histopathological alterations in liver and gills were assessed. Chub specimens from Korenita River had higher concentrations of As, Ba and Pb in all three investigated tissues as well as higher total histopathological index values than chub from reservoirs. Specimens from Međuvršje reservoir were characterized by higher values for concentrations of Cu and Si in muscle tissue and higher values for regressive histopathological alterations in gills. Individuals of chub from Kruščica reservoir had the highest concentrations of Fe in liver, Hg in muscle and Sr and Zn in muscle while gills had the lowest value of total histopathological index. The results from the present study showed higher level of histopathological alterations as a result of mine tailing accident. As a result of mixed contamination on the Međuvršje site, histopathological index values of gills were in line with the index value from Korenita River. Increased values for Fe and Sr in chub tissue from Kruščica reservoir could be explained by geological structure of the site which is characterized by magmatic rock rich in Cu, Fe and Ni as well as dominant carbonate sediment complex of marine origin with increased level of Sr.

Reclaimed Water Irrigation Effect on Agricultural Soil and Maize (Zea mays L.) in Northern China

The concentration, spatial distribution, and source of trace metals (As, Cd, Cu, Cr, Pb, and Zn) are investigated in agricultural soils and maize (Zea mays L.) subjected to two distinct types of irrigation water in Northern China. The results indicate that the concentration of trace metals in soils irrigated for approximately 30 years with reclaimed water exhibit only minor differences in comparison to that irrigated with groundwater. However, the use of reclaimed water appear to result in higher concentrations of As and Cu in the agricultural soils. Geo‐statistical and principal component analyses suggest that Cr has a lithogenic origin and Cd, Pb, and Zn are mainly influenced by other human activities (e.g., vehicle emissions in case of Pb). With regards to maize, no significant differences in metal concentrations are observed in the grains. The highest concentrations of Cd are measured in the roots, whereas elevated concentrations of Cr and Pb are found in the leaves. Cu and Zn, as necessary elements for plant growth, have higher concentrations in grains compared to the other trace metals. The observed increase of Cu and As concentrations in soils and the concentration of Pb from both areas in grains of maize exceed the safety level, indicating that continued monitoring is required to insure food safety and sustainable crop production.

HISTOPATHOLOGICAL CHANGES IN LIVER AND GILLS OF Odontesthes bonariensis INHABITING A LAKE WITH HIGH CONCENTRATIONS OF ARSENIC AND FLUORIDE (CHASICÓ LAKE, BUENOS AIRES PROVINCE)

Water bodies in the Chaco-Pampean plain contain arsenic (As) and fluoride (F – ) occurring naturally. Chasico Lake, located in the southwest of Buenos Aires Province, has high concentrations of both elements (As, 0.05-0.41 mg/L; F – , 6.74-8.54 mg/L). Fish can be considered as indicators of environmental pollution. The aim of this study was to analyze whether the presence of high concentrations of As and F – found in the liver and gills of Odonthestes bonariensis could be associated to histological changes found in these tissues. Fish were sampled from different locations of the lake. Tissue samples (liver and gills) were subdivided and subjected to an acid digestion to determine As and to an alkaline digestion to determine F – . Morphological changes were assessed using routine histological techniques. As concentrations in the liver were higher than in the gills, while the gills showed higher F – concentrations. The histological examination of the liver and gills showed alterations that could correspond to the effects of the high As and F – concentrations found in these tissues. The toxicity of these elements is due to oxidative stress. Silverside is one commercially relevant fish in Buenos Aires and a key species in the food chain in the region. Therefore, further histopathological studies are relevant to guarantee this fish’s health and safety for human consumption.

Total and Bioaccessible Soil Arsenic and Lead Levels and Plant Uptake in Three Urban Community Gardens in Puerto Rico.

Arsenic (As) and lead (Pb) are two contaminants of concern associated with urban gardening. In Puerto Rico, data currently is limited on As and Pb levels in urban garden soils, soil metal (loid) bioaccessibility, and uptake of As and Pb in soil by edible plants grown in the region. This study examined total and bioaccessible soil As and Pb concentrations and accumulation in 10 commonly grown garden plants collected from three urban community gardens in Puerto Rico. Bioavailability values were predicted using bioaccessibility data to compare site-specific bioavailability estimates to commonly used default exposure assumptions. Total and bioaccessible As levels in study soils ranged from 2 to 55 mg/kg and 1 to 18 mg/kg, respectively. Total and bioaccessible Pb levels ranged from 19 to 172 mg/kg and 17 to 97 mg/kg, respectively. Measured bioaccessibility values corresponded to 19 to 42% bioaccessible As and 61 to 100% bioaccessible Pb when expressed as a percent of total As and Pb respectively. Predicted relative percent bioavailability of soil As and Pb based on measured bioaccessibility values ranged from 18 to 36% and 51 to 85% for As and Pb respectively. Transfer factors (TFs) measuring uptake of As in plants from soil ranged from 0 to 0.073 in the edible flesh (fruit or vegetable) of plant tissues analyzed and 0.073 to 0.444 in edible leaves. Pb TFs ranged from 0.002 to 0.012 in flesh and 0.023 to 0.204 in leaves. Consistent with TF values, leaves accumulated higher concentrations of As and Pb than the flesh, with the highest tissue concentrations observed in the culantro leaf (3.2 mg/kg dw of As and 8.9 mg/kg dw of Pb). Leaves showed a general but not statistically-significant (α = 0.05) trend of increased As and Pb concentration with increased soil levels, while no trend was observed for flesh tissues. These findings provide critical data that can improve accuracy and reduce uncertainty when conducting site-specific risk determination of potential As and Pb exposure while gardening or consuming garden produce in the understudied region of Puerto Rico.

Intertidal geothermal hot springs as a source of trace elements to the coastal zone: A case study from Bahía Concepción, Gulf of California

We investigated the influence of the intertidal geothermal hot spring (GHS) on the biogeochemistry of trace elements in Santispac Bight, Bahía Concepción (Gulf of California). The geothermal fluids were enriched in As and Hg mainly in ionic form. The suspended particulate matter of the GHS had elevated enrichment factor (EF) >1 of As, Bi, Cd, Co, Cu, Mn, Mo, Sb, Sn, Sr, Ti, U and Zn. The sediment core from GHS1 had high concentration of As, Hg, Corg, S, V, Mo, and U and the extremely high EF of these elements at 8cm of the core. The maximum bioaccumulation of As and Hg was in seaweeds Sargassum sinicola collected near the GHS2. The results confirm the input of trace elements to the coastal zone in Bahía Concepción from geothermal fluids and the evident modification of the chemical composition of the adjacent marine environment.

Biomonitoring of Trace Metals in the Keban Dam Reservoir (Turkey) Using Mussels (Unio elongatulus eucirrus) and Crayfish (Astacus leptodactylus).

Freshwater mussels and crayfish are commonly used as biomonitors of trace metals. In the present study, the concentrations of ten metals were determined in mussels (Unio elongatulus eucirrus) and crayfish (Astacus leptodactylus) collected from the Keban Dam Reservoir in Turkey. The significant spatial differences in concentrations of studied metals except As in mussels were not found. However, Co, Cr, Cu, and Zn concentrations in mussels and As, Co, Cu, Fe, Pb, and Zn concentrations in crayfish showed significant seasonal differences. As, Cd, and Mn levels in mussels were about nine times higher than those in crayfish. The concentrations of Cd, Cr, Cu, Pb, Zn, and inorganic As in crayfish and mussels were lower than maximum permissible levels. When compared with other biomonitoring studies using mussels and crayfish, high concentrations of As, Cd, Co, Cr, and Ni in mussels and Cr and Ni in crayfish were observed due to lithogenic sources and anthropogenic activities in the basin. Bioconcentration factor values of Fe, Mn, Cd, and Zn in mussels and Zn, Cu, Fe, and Co in crayfish were > 1000, which indicates that both U. e. eucirrus and A. leptodactylus have potential to bioaccumulate these metals. Therefore, attention should be paid to mussels and crayfish from ecological and human health perspective, because they are potential vectors of metals to higher trophic levels.

A Regional Scale Investigation on Groundwater Arsenic in Different Types of Aquifers in the Pearl River Delta, China

Nearly 400 groundwater samples were collected from different types of aquifers in the Pearl River Delta (PRD), and the concentrations of groundwater arsenic (As) and other 22 hydrochemical parameters in different types of aquifers were then investigated. Results showed that groundwater As concentration was up to hundreds μg/L in granular aquifers, while those in fissured aquifers and karst aquifers were only up to dozens and several μg/L, respectively. Correspondingly, about 9.4% and 2.3% samples with high concentrations (>0.01 mg/L) of As were in granular and fissured aquifers, respectively, but no samples with high concentration of As were in karst aquifers. The source and mobilization of groundwater As in granular aquifers are likely controlled by the following mechanism: organic matter in marine strata was mineralized and provided electrons for electron acceptors, resulting in the release of NH4+ and I- and the reduction of Fe/Mn and NO3-, and was accompanied with the mobilization of As from sediments into groundwater. By contrast, both natural processes including the competitive adsorption between As anions and F-/PO43-/HCO3- and anthropogenic processes including industrialization were responsible for high concentrations of groundwater As in fissured aquifers.

Risk Assessment of Potentially Toxic Elements (PTEs) Pollution at a Rural Industrial Wasteland in an Abandoned Metallurgy Factory in North China.

The potential toxic elements (PTEs) pollution problems in many rural industrial wastelands have been observed to be conspicuous. Therefore, 40 top soil samples were collected from the wasteland of a typical rural metallurgy factory in Baoding, China. The total concentrations of six key PTEs were measured. The soil properties and speciation of the PTEs were also identified. Extremely high concentrations of As, Cd, Pb, and Zn were observed in the surface soils. Using the PTEs concentration in the top soils of the rural industrial wasteland, the following indices of pollution were calculated: the pollution load index (PLI), the geo-accumulation Index (Igeo), the risk assessment code (RAC), and the health risk assessment (HRA). The analysis of the PLI and Igeo indicated that site #1 was relatively clean, while sites #2 and #3 were heavily polluted. The results of the RAC showed that PTEs in top soils at sites #2 and #3 were significantly increased (p < 0.05) for Cd and Zn. The HRA indicated that both As and Pb presented non-carcinogenic risks to children and adults at sites #2 and #3. Our findings can be a reference for risk prevention of industrially abandoned land in rural China.

Preliminary trace element analysis of arsenic in Nepalese groundwater may pinpoint its origin

Arsenic contamination of groundwater used as drinking water in South Asia poses a serious health threat to the inhabitants living on alluvial plains of the Himalayan foreland of countries like Bangladesh, India, Nepal and Myanmar. Although the geological and geochemical conditions favoring the release of the highly poisonous contaminant from the sediments hosting the groundwater are meanwhile quite well understood, there is still a significant debate about the origin of arsenic. The sediments forming a huge proportion of the Terai (lowlands of Nepal) aquifers are derived from two main sources, (i) sediments deposited by large rivers that erode the upper Himalayan crystalline rocks and (ii) weathered meta-sediments carried by smaller rivers originating in the Siwalik foothills adjacent to the Terai. In this article a so far underestimated source of As is discussed: the peraluminous leucogranites found ubiquitously in the Nepal Himalaya. The relationship between the trace elements analyzed in the groundwater in the Terai and trace elements found in such felsic rocks reflect the origin of the arsenic in the high Himalayas of Nepal. In addition to the high concentration of As, a striking feature is the presence of the lithophile trace elements like Li, B, P, Mn, Br, Sr and U in the groundwater. The mentioned elements point to a felsic initial source like metapelites or leucogranites—all rocks showing a high abundance of especially B, P and As as well as Cd and Pb.

Biogeochemical assessment of the urban area in Moscow.

The biogeochemical and ecological assessment of the industrial city territory including urban soils and trees was carried out. Chemical (macroelement and microelement) composition of the city soils, morphological and biochemical properties of the linden leaves, possible impact of de-icing salts on soil and tree state, the correlation between the content of trace elements, and the S-containing plant compounds (phytochelatins) were included in the assessment. It was found that concentrations of trace elements in the soils near road with intensive traffic are changed from the soils, located at a distance of 40-50m from the road. They have higher concentrations of As, Fe, Mn, Se, and Sr and lower concentration of Zn. The linden leaves from the roadside were characterized by the increase in As, Cu, Fe, Zn, and Cr and sharp decrease in the Mn and Sr concentrations. The analysis of soil water extracts showed a slight decrease of pH and low content of Ca, Mg, K, and Na for the distant sites. The phytochelatin test of linden leaves was weakly effective as well as asymmetry degree study of leaf lamina. The main differences were observed in the damage symptoms of leaves (chlorosis and necrosis) and the content of pigments (chlorophyll and carotenoids). The biochemical and ecological assessment of soils and trees showed relatively satisfactory ecological state of the investigated area in Moscow. The data obtained shows the weak local impact of the application of de-icing salts and automobile emissions.

Trace elements in a Mediterranean scorpaenid fish: Bioaccumulation processes and spatial variations

The black scorpionfish Scorpaena porcus, a carnivorous sedentary species, was studied as an indicator of local trace element (TE) contamination of coastal fish species in the northwestern Mediterranean Sea. Fish were collected in seagrass meadows in winter 2012 at four sampling sites: three were located near Marseille, a highly urbanized and industrial area that is subjected to various types of contaminant inputs, and one was located near Hyères, a less urbanized area. Size, sex, age and diet of fish were determined before stable isotope and TE analyses. C and N isotopic compositions and concentrations of nine TEs (As, Ba, Cd, Cu, Cr, T-Hg, Ni, Pb, and Zn) were determined in dorsal white muscle. Most TEs did not bioaccumulate in S. porcus, as no increase in TE concentrations with increasing size, age or trophic level of fish was evident. Total mercury (T-Hg) was the only element to bioaccumulate and biomagnify, displaying strong positive correlations of its concentration with age (r = 0.88, p < 0.01), length (r = 0.84, p < 0.01) and δ15N value (r = 0.68, p < 0.01). Compared with the reference site, higher concentrations of As, Ba, Cd, T-Hg, Pb, and Zn were recorded in fish collected at one or all of the Marseille site. In contrast, no difference was observed for Cr, Cu, and Ni concentrations with site. Spatial differences in TE concentrations in S. porcus were related to differences in isotopic composition and to the primary environmental characteristics and human activities prevailing at each site. Concentrations of Cd, T-Hg and Pb in fish muscle (priority substances for monitoring) were all below the maximum permitted European values.

Metal bioaccumulation and oxidative stress profiles in Ruditapes philippinarum – insights towards its suitability as bioindicator of estuarine metal contamination

The Manila clam Ruditapes philippinarum is an invasive bivalve in Europe, widely distributed, with a great ability to tolerate a broad range of environmental conditions. Despite the ability to reflect contamination, its suitability as bioindicator is not consensual. This study provided clarification on this issue by evaluating the ability of R. philippinarum to signalise trace element contamination in an estuary chronically impacted by metals and metalloids (Tagus estuary, Portugal). A multidimensional approach was carried out in two differently contaminated sites (Barreiro – BAR; Alcochete – ALC) in warm and cold periods, combining sediment contamination, bioaccumulation of trace elements (As, Cd, Pb and Hg), and a battery of oxidative stress biomarkers in two R. philippinarum organs (digestive gland and gills). Sediments from BAR exhibited higher concentrations of all the elements than those from ALC, in line with the anthropogenic pressures identified for both estuarine areas. Likewise, clams from BAR showed higher concentrations of As and Pb in the digestive gland (cold period) and Pb in the gills (warm and cold periods) in comparison with ALC. These results suggest the capacity of R. philippinarum to reflect external levels of exposure to those elements into tissue loads. However, an opposite spatial variation was consistently found for Hg accumulation in the digestive gland and gills in both periods, as well as for Cd in the gills in the warm season. The results reinforce the idea that trace element accumulation patterns depend not only on the external bioavailability, but also on the toxicokinetics that is trace element-specific. Despite the two contrasting patterns found for bioaccumulation in R. philippinarum (mainly Pb vs. Hg), oxidative stress parameters were able to signalise BAR as the most impacted area. In fact, the digestive gland of BAR clams exhibited higher GST activity and GSHt levels (in both sampling periods) and SOD activity (warm season), presumably to cope with the enhanced accumulation of Pb and As. Moreover, variations of gills’ CAT and SOD activities (warm period) agreed with the elevated accumulation of Pb at BAR. Overall, the characteristics of this invasive species could lead to a biased interpretation of the environmental quality status, particularly when based on trace element bioaccumulation only, reinforcing the need to adopt a multi-level/-species approach on environmental assessment studies.

Quantification of health risks in Ecuadorian population due to dietary ingestion of arsenic in rice.

In Ecuador alone, 500,000 people in rural areas are estimated to have been exposed to high concentrations of As from water and food, but no quantitative evaluation of health risk has yet been made. The present study quantifies exposure and health risk for the Ecuadorian population from the ingestion of arsenic in white rice. Estimated exposure is correlated with published data on tap water quality and biomarkers of exposure for the population of two towns in the metropolitan area of Quito. Estimated daily intake (EDI) of arsenic for infants living in urban areas of Ecuador is around four times that of European infants, being equal for those livings in rural areas. EDI for the population as a whole is almost twice that of Europe, but between a half and a third of that of Brazil, Bangladesh, and India. Estimated excess lifetime risk (ELTR) for adults is 3 per 10,000, while for infants varies between 10 per 10,000 in rural areas and 20 per 10,000 in urban areas. Future research on arsenic impacts on human health in Ecuador should consider in particular poor populations living in regions where environmental arsenic concentrations are highest, including cross-sectional and longitudinal epidemiologic studies.