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EC number: 932-476-9 | CAS number: -
The most likely exposure pathway to humans is inhalation of the dust of fine-grained ferrous slag.
Dermal and oral repeated exposure is insignificant and consider as not critical and or not relevant for the users/human, based on expected uses.
GGBS is considered to cover the worst-case of ferrous slag, because it is intentionally ground for the cement industry and thus contains by far the highest amount of fine and inhalable particles compared to other types of ferrous slag.
From single-dose toxicity testing in animals via the oral, dermal and inhalation routes it can be concluded that ferrous slags are not acutely toxic. A acute 4 -week inhalation toxicity study in rats by GGBS conducted by Bayer Healthcare 2012, concentration-and-time-related onset of lung changes were monitored up to 90 days after a single short-term exposure to GGBS. The findings showed no likely acute inhalation hazard, based on the limit test data (LC50 > 5235 mg GGBS/m³), and ferrous slags can be expected to be virtually non-toxic after inhalation exposure. A short-term study (28 days) to repeated inhalation exposure to GGBS in rats up to 24 ug/L, was done by Charles River Laboratories, 2015. There were no death or adverse clinical signs during the study period and no evidence of lung injury could observed. Based on the result in this study, the NOAEL was determined to 24 ug/L (target concentration) or 24.9 ug/L (achieved concentration).
The aim of the studies was to provide information on health hazards likely to arise from short-term or long-term exposure to ferrous slags by the inhalation route.
A sub-chronic toxicity study (90 days) for inhalation does not need to be conducted because the substance (slags) is unreactive, insoluble and not inhalable and there is no evidence of absorption and no evidence of toxicity in a 28 day short-term study and human exposure is limited.
A short term-toxicity study by the oral and or dermal route does not need to be conducted because an appropriate inhalation study is available and inhalation is the most appropriate route of administration as based on the expected uses, exposure assessment and the chemical- and physico properties of the slags.
The substance is a solid at room temperature and no or very little dust (below the work place limit value for inhalable dust of 10 mg/m³ and for respiratory dust of 3 mg/m³ which applies for inert dust in some of the European countries) is formed for the intended uses. The work place limit values are routineously monitored in all relevant workplaces were a significant exposure to slag dust may occur. Uptake of fine slag dust into the lungs does not significantly affect the levels of trace metals in the lung associated lymph nodes. The half live of slag dust in the lungs is approximately 60 d suggesting that slags are inert dust without hazardous effect on the respiration system.
Ferrous slags are solid UVCB substances (substances of Unknown or Variable composition, Complex reaction products or Biological materials) that resemble natural rocks found in terrestrial and sediment systems. The physicochemical properties are almost identical among ferrous slags, and their benign toxicological and ecotoxicological profiles are very similar. Similarities comprise also the mineralogical composition of the ferrous slags. Importantly, all mineral components of ferrous slags are present in natural rocks; no new component is introduced during steel processing. Ferrous slags demonstrate low extractability in water as metals in slag were found to be generally resistant to leaching. Ferrous slags are virtually free of hazardous fibres. Overall, ferrous slags can be considered artificial volcanic rocks.
The ‘Ferrous Slag Category’ comprises the following 5 slag types: (1) ABS/GBS i.e., Slag, ferrous metal, blast furnace (air cooled or granulated), (2) BOS i.e., Slag, steelmaking, converter (converter slag), (3) EAF C i.e., Slag, steelmaking, elec. furnace (carbon steel production), (4) EAF S i.e., Slag, steelmaking, elec. furnace (stainless/high alloy steel production), and (5) SMS i.e., Slag, steelmaking. No significant hazard to environmental and ecological receptors has been anticipated for these slags.
The pathways of exposure quantitatively evaluated in this assessment were inhalation of suspended airborne ferrous slag particulates, incidental ingestion of ferrous slag, and dermal contact with ferrous slag.
From single-dose toxicity testing in animals via the oral, dermal and inhalation routes it can be concluded that ferrous slags are not acutely toxic. They do not need to be classified as oral, dermal and inhalation toxicants; neither a signal word nor hazard statement is required. Furthermore, ferrous slags exhibit no relevant irritant or sensitising potential, and does not show any mutagenic potential. Extensive testing in rat inhalation studies revealed that the biological responses to inhaled ferrous slag show no correlation to the course of pulmonary toxicity reported for amorphous silica (quartz); quartz dust served as positive control as it is well known to produce irreversible lung damage. Overall, ferrous slag in vivo data differ markedly from those reported for quartz in rats exposed at similar doses.
Supplemental in vitro testing also shows that ferrous slags, alike natural mineral samples, do not cause significant toxicity in cultured alveolar macrophages, nor does the slags induce major reactive oxygen species (ROS) formation and oxidative stress or trigger any inflammation in a biological system. On the contrary, the positive assay control quartz caused consistently evidence for an inflammation response in vitro associated with a significant secretion of the mature forms of pro-inflammatory cytokines from the cells, strong activation of the inflammasome pathway, and impaired phagocytosis functionality of alveolar macrophages.
Taken together the data generated in vivo and in vitro for ferrous slags it can be summarised that ferrous slags behave like natural rock, representing a rather inert category of UVCB substances. As expected biokinetics investigations in rats following inhalation exposure to high concentrations of ferrous slag particulates showed concentration-dependent lung burdens of persistent metals after inhalation exposure of rats to ferrous slags but there was no translocation to other organs of any metal investigated. The animal data suggest that the rat lung was able to get rid of the inhaled solid aerosol via physiological clearance mechanisms.
The toxicology programme for ferrous slags, as documented in the Chemical Safety Report (CSR) as part of the registration dossier of ferrous slags (CSR 2017), can be considered to fulfil information requirements for REACH (Registration, Evaluation, Authorisation and Restriction of Chemical substances) registration at the European Chemicals Agency (ECHA). There is sufficient, adequate and reliable information on hazardous properties for classification and risk assessment of ferrous slags.
The registrant makes use of Annex XI criteria regarding the scientific necessity of information, the technical possibility for testing, and exposure-based waiving to adapt the standard information requirements under REACH. These non-clinical studies are waived based on physico-chemical properties of ferrous slags that resemble natural rocks, mimicking the natural concentration of an element in the environment, and the low solubility in water, low extractability of components from ferrous slags, and lack of toxicological bioavailable fraction / systemic bioavailability of metals. Slag has been utilised in road construction for more than two centuries and wealth of humane experiences are available. Furthermore, ferrous slags have no PBT (persistent, bioaccumulative and toxic) or vPvB (very persistent and very bioaccumulative) properties. It is also of note that no toxicity effects of particular concern were observed in animal inhalation studies that is the likely route of human exposure, and results obtained from suitable in vitro studies demonstrate no certain dangerous property of ferrous slags. Finally, previous risk assessments of slags provide sufficient supporting evidence that toxicity can reliably be excluded.
There is no evidence for a toxicologically significant potential to ferrous slags after repeated inhalation exposures, based on the test results from the short-term inhalation studies.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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