Ladle skimming slag, Ladle furnace refining, slag, Ferrous slag

Endpoint summary

Description of key information

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.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

24.9 mg/m³

Study duration:

subacute

Species:

rat

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Toxicity studies are not available for Slag, Pig Iron ladle refining, non-granulated, water-cooled. Read-across to the assessment entity (analogue approach) to slags, steelmaking is applied for the assessment of Slag, Pig Iron ladle refining, non-granulated. Based on results of a leaching experiment performed with the target substance (i.e., Slag, Pig Iron ladle refining, non-granulated, water-cooled) and the source substance (i.e., slags steelmaking) solved metal ion concentrations of the target substance are similar to the solved metal concentrations of the source substance. Read-across is fully justified and discussed in detail in the RAAF document attached on IUCLID section 13.

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.