ABSTRACT
Trace elements (TEs) are those elements that are found in relatively small concentrations in soil; some of the TEs have toxic effects to organisms, including plants and humans. Therefore, various countries and organizations around the globe have set up regulation limits in soils. These limits are element-specific and usually differ according to soil use, soil properties, or both. Here, we aimed at collecting, reviewing, and critiquing soil TE regulation limits around the globe. We distinguished limits mostly in residential, industrial, and agricultural soil uses, and we also listed those countries that do not have categories for limits according to land use. Further, we showed a variety of problems linked with these regulation limits. First, countries do not regulate the same TEs, with some important and well-known toxic elements not being regulated in major countries (e.g., As is not listed in the European Union Directive and in India). Thus, countries have not agreed on a minimum ground concerning TE-induced contamination risk. Second, regulation limits do not take into account TE mobility to plants and water. Third, limits for the same TEs are very different among countries. This work exhibits the need of reducing the existing diversity in regulation limits by drafting soil legislations of worldwide validity. We suggest that limits should be developed and harmonized across the globe that would take into account soil-to-plant mobility, and that would reconsider multi-element contamination cases, where risks enhance due to synergistic effects.
