Aurélie Pelfrêne

Cd, Pb and Zn Oral Bioaccessibility of Urban Soils Contaminated in the Past by Atmospheric Emissions from Two Lead and Zinc Smelters

Ingestion of dust or soil particles could pose a potential health risk due to long-term metal trace element (MTE) exposure. Twenty-seven urban topsoil samples (kitchen garden and lawn) were collected and analyzed for Cd, Pb and Zn using the unified Bioaccessibility Research Group of Europe (BARGE) method (UBM) test to estimate the human bioaccessibility of these elements. The quantities of Cd, Pb and Zn extracted from soils indicated, on average, 68, 62 and 47% bioaccessibility, respectively, in the gastric phase and 31, 32 and 23% bioaccessibility, respectively, in the gastro-intestinal phase. Significant positive correlations were observed between concentrations extracted with UBM and total MTE contents. Stepwise multiple regression analysis showed that human bioaccessibility was also affected by some physico-chemical soil parameters (i.e. total nitrogen, carbonates, clay contents and pH). The unified test presents some valuable data for risk assessment. Indeed, the incorporation of oral bioaccessible concentrations into risk estimations could give more realistic information for health risk assessment.

Assessment of potential health risk for inhabitants living near a former lead smelter. Part 1: metal concentrations in soils, agricultural crops, and homegrown vegetables

Soil contamination by metals engenders important environmental and health problems in northern France where a smelter (Metaleurop Nord) was in activity for more than a century. This study aims to look at the long-term effects of the smelter after its closedown by combining data on the degree of soil contamination and the quality of the crops grown (agricultural crops and homegrown vegetables) in these soils for a better assessment of the local population’s exposure to Cd, Pb, and Zn. Seven years after the Metaleurop Nord closedown, (1) the agricultural and urban topsoils were strongly contaminated by Cd, Pb, and Zn; (2) the kitchen garden topsoils were even more polluted than the agricultural soils, with great variability in metal concentrations within the gardens studied; (3) a high proportion of the agricultural crops for foodstuffs did not conform with the European legislation; (4) for feedstuffs, most samples did not exceed the Cd and Pb legislation limits, indicating that feedstuffs may be an opportunity for most agricultural produce; and (5) a high proportion of the vegetables produced in the kitchen gardens did not conform with the European foodstuff legislation. The high contamination level of the soils studied continues to be a risk for the environment and the population’s health. A further investigation (part 2) assesses the associated potential health risk for local inhabitants through consumption of homegrown vegetables and ingestion of soil particles by estimating the site-specific human health assessment criteria for Cd and Pb.

Contamination, Fractionation and Availability of Metals in Urban Soils in the Vicinity of Former Lead and Zinc Smelters, France

Abstract Soil contamination by metals from anthropogenic activities (e.g., mining and smelting) is a major concern for the environment and human health. Environmental availability of cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), and indium (In) in 27 urban soils located around two former Pb and Zn smelters in Northern France were studied by analysing the chemical forms of these metals and evaluating their phytoavailability. These metals were determined using flame or electrothermal absorption atomic spectrometry (FAAS or ETAAS), depending on their concentration levels. After optimisation of the ETAAS method, characteristic mass of In in water and aqua regia were 9.9 and 18 pg, respectively, showing the high sensitivity of the analytical procedure. Metal partitioning was conducted using a four-step sequential extraction procedure. The results showed that Cd and Zn were mainly in the acid-extractable and reducible forms in the urban soils studied. In contrast, Pb and In were largely in the reducible fraction. However, in some samples, the amount of In extracted in the residual or exchangeable fraction was higher than that in the reducible fraction. Copper was mainly found in the reducible and residual fractions. A pot experiment was conducted in a glasshouse with seven soils (six contaminated and one uncontaminated) and two plant species, ryegrass and lettuce. The results showed transfer of metals from the contaminated soils to the shoots of ryegrass and the edible part of lettuce. The metal bioconcentration factor was in the order of Cd ≫ Cu > In > Zn ≫ Pb for lettuce leaves, whereas for ryegrass shoots, three orders were found, Cd > Zn > Cu ≫ In > Pb, Cd ≥ In > Zn > Cu ≫ Pb, and Zn > Cd > Cu > In > Pb, depending on the physico-chemical properties of the soils, such as pH, cation exchange capacity, carbonates, and organic matter. It was established that the metal toxicity was related to the contamination levels and the physico-chemical properties, including pH, organic matter, and in a lesser extent, Ca, Mg, and phosphorus contents, of the soils. However, it was shown that lettuce could grow on soils having high Cd and CaCO3 contents. Cadmium was one of the most available metals while Pb was always the least available in the soils studied.

Bioaccessibility of trace elements as affected by soil parameters in smelter-contaminated agricultural soils : a statistical modeling approach

An investigation was undertaken to identify the most significant soil parameters that can be used to predict Cd, Pb, and Zn bioaccessibility in smelter-contaminated agricultural soils. A robust model was established from an extended database of soils by using: (i) a training set of 280 samples to select the main soil parameters, to define the best population to be taken into account for the model elaboration, and to construct multivariate regression models, and (ii) a test set of 110 samples to validate the ability of the regression models. Total carbonate, organic matter, sand, P(2)O(5), free Fe-Mn oxide, and pseudototal Al and trace element (TE) contents appeared as the main variables governing TE bioaccessibility. The statistical modeling approach was reasonably successful, indicating that the main soil factors influencing the bioaccessibility of TEs were taken into account and the predictions could be applicable for further risk evaluation in the studied area.

Assessment of potential health risk for inhabitants living near a former lead smelter. Part 2: site-specific human health risk assessment of Cd and Pb contamination in kitchen gardens

Metal contamination of urban soils and homegrown products has caused major concern. In Part 1, we investigated the long-term effects of a former smelter on the degree of kitchen garden-soil contamination and the quality of the homegrown vegetables from these gardens. The results showed that the soils retained a high level of contamination and that a large proportion of the vegetables produced did not comply with the legislation on the levels of metals allowed for human consumption. The present study aims to assess the associated potential health risk to local inhabitants through consumption of homegrown vegetables and ingestion of soil particles using a land use-based approach. For lead (Pb), the standard hazard quotient (HQ)-based risk assessment method was used to determine the HQ. For cadmium (Cd), the approach consisted of calculating the HQs and then deriving site-specific assessment criteria (SSAC) using the SNIFFER method. The results suggested that the exposure pathways considered should not engender any form of deleterious health effects for adults. For children, Pb was the main concern and induced a relatively high health risk through soil particle ingestion, and most total soil Cd concentrations exceeded the derived SSAC, in particular, through consumption of vegetables. The metal bioaccessibility in soils was incorporated into the methods to establish more realistic risk assessment measures. This study proposes an approach to integrate different human health risk assessment methods. Further investigations should complete the assessment to improve risk determination, e.g., the determination of metal bioaccessibility in vegetables.

In vitro digestion and DGT techniques for estimating cadmium and lead bioavailability in contaminated soils: influence of gastric juice pH.

A sensitivity analysis was conducted on an in vitro gastrointestinal digestion test (i) to investigate the influence of a low variation of gastric juice pH on the bioaccessibility of Cd and Pb in smelter-contaminated soils (F(B), using the unified bioaccessibility method UBM) and fractions of metals that may be transported across the intestinal epithelium (F(A), using the diffusive gradient in thin film technique), and (ii) to provide a better understanding of the significance of pH in health risk assessment through ingestion of soil by children. The risk of metal exposure to children (hazard quotient, HQ) was determined for conditions that represent a worst-case scenario (i.e., ingestion rate of 200 mg day(-1)) using three separate calculations of metal daily intake: estimated daily intake (EDI), bioaccessible EDI (EDI-F(B)), and oral bioavailable EDI (EDI-F(A)). The increasing pH from 1.2 to 1.7 resulted in: (i) no significant variation in Cd-F(B) in the gastric phase but a decrease in the gastrointestinal phase; (ii) a decrease in soluble Pb in the gastric phase and a significant variation in Pb-F(B) in the gastrointestinal phase; (iii) a significant decrease in Cd-F(A) and no variation in Pb-F(A); (iv) no change in EDI-F(B) and EDI-F(A) HQs for Cd; (v) a significant decrease in EDI-F(B) HQs and no significant variation in EDI-F(A) HQ for Pb. In the analytical conditions, these results show that risk to children decreases when the bioavailability of Pb in soils is taken into account and that the studied pH values do not affect the EDI-F(A) HQs. The present results provide evidence that the inclusion of bioavailability analysis during health risk assessment could provide a more realistic estimate of Cd and Pb exposure, and opens a wide field of practical research on this topic (e.g., in contaminated site management).

In Vitro Investigations of Human Bioaccessibility from Reference Materials Using Simulated Lung Fluids

An investigation for assessing pulmonary bioaccessibility of metals from reference materials is presented using simulated lung fluids. The objective of this paper was to contribute to an enhanced understanding of airborne particulate matter and its toxic potential following inhalation. A large set of metallic elements (Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, and Zn) was investigated using three lung fluids (phosphate-buffered saline, Gamble’s solution and artificial lysosomal fluid) on three standard reference materials representing different types of particle sources. Composition of the leaching solution and four solid-to-liquid (S/L) ratios were tested. The results showed that bioaccessibility was speciation- (i.e., distribution) and element-dependent, with percentages varying from 0.04% for Pb to 86.0% for Cd. The higher extraction of metallic elements was obtained with the artificial lysosomal fluid, in which a relative stability of bioaccessibility was observed in a large range of S/L ratios from 1/1000 to 1/10,000. For further investigations, it is suggested that this method be used to assess lung bioaccessibility of metals from smelter-impacted dusts.

Investigation of DGT as a metal speciation tool in artificial human gastrointestinal fluids

This paper reports the results of an investigation on the performance of the diffusive gradient in thin film technique (DGT) as a speciation tool for trace elements (TEs) in artificial human gastrointestinal fluids. The validity of Cd, Pb, and Zn sampling by DGT in digestive fluids was checked. The TE bioaccessibility in highly contaminated soils was determined using the in vitro Unified Barge Method (UBM) test. DGT devices were deployed in the gastrointestinal solutions obtained after carrying out the UBM test. The computer speciation code JESS (Joint Expert Speciation System) was used to predict the metal speciation of Cd, Pb, and Zn. Combining the in vitro test with the DGT technique and JESS provided an approach to the TE species available for transport across the intestinal epithelium. The gastrointestinal absorption of ingested TE ranged from 8 to 30% for Cd, 0.6 to 11% for Pb, and 0.8 to 7% for Zn and was influenced by TE speciation. In this original approach, the DGT technique was found to be simple and reliable in the investigation of TE chemical speciation in digestive fluids. Extrapolation to the in vivo situation should be undertaken very cautiously and requires further investigation.

Determining the influence of the physicochemical parameters of urban soils on As availability using chemometric methods: A preliminary study

An initial exploration was conducted using mathematical and statistical methods to obtain relevant information about the determination of the physicochemical parameters capable of controlling As uptake by ryegrass grown on contaminated topsoils. Concentrations of As in the soils were from 10 to 47mg/kg, mainly in the As(V) form (57%-73%). Concentrations of As in water extracts were very low (61-700μg/kg). It was suggested that As(III) was mainly in the uncharged species and As(V) in the charged species. Chemometric methods revealed that the values of the ratio As(III)/As(V) depended on the assimilated-phosphorus, the pseudo-total and water-extractable Fe contents and the soil pH. Arsenic concentrations measured in ryegrass shoots ranged from 119 to 1602μg/kg. Positive linear correlations were obtained between As in ryegrass shoots and water extractable-As. The transfer coefficient of As correlated well with the ratio assimilated-phosphorus/Fe-oxides. As(III) uptake by the shoot of ryegrass was controlled by the organic matter and Fe-oxide contents.

Effects of Iron Concentration Level in Extracting Solutions from Contaminated Soils on the Determination of Zinc by Flame Atomic Absorption Spectrometry with Two Background Correctors

Zinc and iron concentrations were determined after digestion, water, and three-step sequential extractions of contaminated soils. Analyses were carried out using flame absorption spectrometry with two background correctors: a deuterium lamp used as the continuum light source (D2 method) and the high-speed self-reversal method (HSSR method). Regarding the preliminary results obtained with synthetic solutions, the D2 method often emerged as an unsuitable configuration for compensating iron spectral interferences. In contrast, the HSSR method appeared as a convenient and powerful configuration and was tested for the determination of zinc in contaminated soils containing high amounts of iron. Simple, fast, and interference-free method, the HSSR method allows zinc determination at the ppb level in the presence of large amounts of iron with high stability, sensitivity, and reproducibility of results. Therefore, the HSSR method is described here as a promising approach for monitoring zinc concentrations in various iron-containing samples without any pretreatment.