Estimating the bioavailability of trace metals/metalloids and persistent organic substances in terrestrial environments: challenges and need for multidisciplinary approaches

Abstract

AbstractDefinitions and terms related to bioavailability and bioaccessibility of trace metals/metalloids and organic contaminants in soil are briefly discussed and critically evaluated. Main distinguishing features of estimating the bioavailability by biological (in vivo) methods are characterized. Assessment of bioaccessibility using biomimetric (in vitro) methods and existing correlations with in vivo tests are summarized. The most promising biomimetric methods can be as follows: CaCl2 extraction for the assessment of metals biouptake into plants; solid-phase micro extraction, supercritical fluid extraction (SFE) under mild conditions as well as Tenax and hydroxypropyl-beta-cyclodextrin (HPCD) extractions for the estimation of biouptake of persistent organic compounds (e.g., polynuclear aromatic hydrocarbons and polychlorinated biphenyls) by soil-dwelling organisms (mainly earthworms); SFE under mild conditions, HPCD and Tenax extraction for the prediction of biodegradability (microbial degradation) of organic contaminants. However, method development should be extended to further classes of substances. In addition, multidisciplinary approaches are needed for (i) standardization and round-robin studies of the most promising biomimetric methods and protocols so that the data obtained in different laboratories can be compared; (ii) further assessment and critical evaluation of correlations between in vitro and in vivo tests; application of chemometric techniques for handling sets of data obtained both by biomimetric and biological methods is of particular importance in order to evaluate new criteria for risk assessment.