Lead availability in soils from Portugal’s Centre Region with special reference to bioaccessibility

Abstract

Previous environmental biomonitoring studies indicated higher environmental lead (Pb) pollution levels at the districts of Aveiro and Leiria (Portugal). In evaluating the risk for human health, which is associated with contaminated soils after oral uptake, total soil concentrations have generally been held against criteria established from toxicological studies based upon the assumption that the uptake of the contaminant is similar in the toxicological studies and from the soils assessed. This assumption is not always valid, as most toxicological studies are carried out with soluble forms of the contaminants, whereas many soil contaminants are or become embedded in the soil matrix and thus exhibit limited availability. This study intends to estimate the soluble fraction of Pb in the soils from central Portugal, and to assess the bioaccessibility of Pb and, hence, infer exposure and risk for human health. Yet, as the physical-chemical properties of the soil exert some control over the solubility of Pb in the surface environment, the relation between such soil properties and the estimated soluble and/or bioaccessible fractions of Pb is also investigated. Other objective, with a more practical nature, was to give some contribution to find a suitable in vitro mimetic of the gastrointestinal tract environment. The results indicate relatively low total metal concentrations in the soils, even if differences between regions were observed. The Aveiro district has the higher total Pb concentration and the metal is in more soluble forms, that is, geoavailable. Soils with higher concentrations of soluble Pb show higher estimates of bioaccessible Pb. Soil pH seems to influence human bioaccessibility of Pb.

Contribution of lead in soil to children’s lead burden, an update

“…Variation in bioaccessibility values was also reported by Caboche et al (2010). In a study conducted with lead levels in topsoil ranging from 54 to 82 mg kg -1 , the percent of soluble lead ranged from 5 to 25% (Patinha et al, 2011). In these and many other studies, either the soluble fraction of lead was extracted from soil or dust or in vitro models simulating gastric and intestinal conditions (Turner, 2011) were used.…”

Distribution of Cd and Cu Fractions in Chinese Soils and Their Relationships with Soil pH: A Meta-Analysis

“…Furthermore, the enrichment factors of PTMs, relative to their total concentrations in soil, were negatively correlated with soil pH [32][33][34]. Experiments indicated that temporary soil acidification accelerated the release of soil PTMs [23,35], while increasing soil pH reduced their leaching and plant uptake [36][37][38]. So far, however, PTM fraction distribution and their relationships between soil pH remain unknown at the national scale.…”

Bioaccessibility of Airborne Particulate-Bound Trace Elements in Shanghai and Health Risk Assessment

“…In addition, this test is not suitable to be carried out where a huge quantity of environmental samples is concerned (Lu et al, 2011). Hence, in vitro studies using bioaccessibility to predict bioavailability are becoming increasingly popular as they are affordable, simpler, fast, ethical, and not restricted by number of samples (Patinha et al, 2012). The other reason for adopting the in vitro bioaccessibility method to determine the bioavailability potential of contaminants is due to its high correlation with the bioavailability index (Ruby et al, 1996).…”