| dc.description.abstract | Electric arc furnace (EAF) slags, the by-product of steel production, have been applied in the residential use as ground cover, raising concerns regarding human health risks and environmental impacts from release and uptake of heavy metals.
In this study, standardized approaches were compared to evaluate the leaching behaviors of EAF slags and multiple size fractions. The pH-dependent testing was used to evaluate constituent leaching under a range of environmental conditions. The screening-level assessment identified aluminum, arsenic, barium, chromium, cobalt, manganese, molybdenum, selenium, strontium, thallium and vanadium as constituents of potential concern (COPCs). Scenario-based assessment for EAF slag under residential use identified aluminum, chromium, cobalt, manganese and selenium as long-term potential concerns due to their high available content and low leaching concentration, while arsenic, barium, molybdenum and vanadium are likely to be depleted within the 30-year assessment period. EAF slag aging can change the release of barium, chromium, selenium and thallium, mainly driven by hydration and carbonation, where fine particles have more hydration and carbonation and higher reaction rates.
A multi-pathway risk assessment was used to evaluate the potential noncarcinogenic and carcinogenic health risks from the identified COPCs. Drinking water was evaluated assuming a dilution and attenuation factor of 20. Hazard quotients for noncarcinogenic risks (HQs) were carried out based on multiple alternative source assumptions (e.g., total content, available content, natural pH and applicable pH domain). By the drinking water pathway, using the pH domain from the natural pH of the slags (~12.5) to the carbonate buffer pH (~8.0), all of the COPCs had HQs less than 1 for adults and children, while the maximum carcinogenic risk was 3x10-5 for arsenic and 9x10-5 for chromium(VI). By incidental ingestion, using the available content of COPCs, the HQs for children were 2 for thallium and 1.5 for manganese, while the carcinogenic risks to children were 2x10-6 from arsenic and 3x10-6 from chromium(VI). However, the extent of risk through the drinking water and incidental ingestion pathways also will be dependent on the quantity and fraction of area coverage of the EAF slag used, which were assumed unconstrained for calculation of the above values. | |
