Slags, granulated, resulting from plasma-enhanced gasification of non-hazardous municipal waste

Endpoint summary

Description of key information

No acute toxicity of any slag
Basis for this conclusion
Oral
ABS, GBS, EAF C: OECD TG 401, rats: LD50 > 2000 mg/kg bw
BOS, SMS: OECD TG 423, rats: LD50 > 2000 mg/kg bw
Inhalation
GGBS: OECD 403, rats: 4 h-LC50 >5235 mg/m3
Skin
BOS, SMS: rats OECD 402, rats: LD50 > 4000 mg/kg

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

5 235 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

4 000 mg/kg bw

Additional information

Read-across hypothesis and justification is given in section 0, see attache report "Justification for read-across approach to ferrous slags category"

Oral

10 reports were identified that provided information on the acute oral toxicity of slags.

7 of these studies followed the method described in OECD TG 401. The following slags were tested:

·       Slags, ferrous metal, blast furnace (air cooled – ABS)

·       Slags, ferrous metal, blast furnace (granulated – GBS)

·       Slags, steelmaking, converter (BOS, 2 studies)

·       Slags, steelmaking, elec. furnace (carbon steel production - EAF C)

·       Slags, steelmaking (SMS; 2 studies; ladle slag and desulfurization slag)

A single dose of at least 2000 mg/kg bw was applied orally to Wistar rats. No mortalities or abnormalities were observed in these studies.

3 reports were published on the data of an exhaustive project on health and environmental safety of steelmaking slags. This project comprised 2 studies performed according to OECD TG 423 on slags, steelmaking, converter (BOS) and on slags, steelmaking (SMS), respectively, applying a dose of 2000 mg/kg bw by gavage. No mortalities or abnormalities were observed in these studies.

Slags, steelmaking, elec. furnace (stainless/high alloy steel production - EAF S) were not tested. Since the major difference between EAF S and EAF C is their content in iron (compounds), data on EAF C are equally valid for EAF S, and almost identical leaching properties, there was no need for additional testing also in regard to animal welfare.

In the rat, all oral LD₅₀values for ABS/GBS, BOS, EAF C, and SMS are higher than 2000 mg/kg bw, which is the maximum LD₅₀requiring classification and labelling. No classification and labelling for acute oral toxicity are required for all ferrous slags.

 

Inhalation

There is one study available on the inhalation toxicity of ferrous slags. As test material slags, ferrous metal, blast furnace (ground, granulated – GGBS) were selected because the majority of blast furnace slag is produced as GBS, which is almost exclusively fine-ground (< 100 µm) for use in cement production. As the marketed products of other slags contain only far smaller proportions of fine particles than GGBS, the testing of GGBS served to cover the worst-case.

To determine the acute inhalation toxicity of GGBS, a test was conducted with rats in accordance to OECD Technical Guideline 403 (2009) and Directive 92/69/EEC. Annex V Method B.2. GGBS was applied as a powder aerosol nose-only to one group of rats for an exposure duration of 4 hours at a concentration of 5235 mg/m³which was also the maximum technically attainable concentration. The aerosol was respirable, i.e. the mass median aerodynamic diameter (MMAD) was 3.1 µm, and the geometric standard deviation was 1.8 µm. The exposure was followed by a postexposure observation period of 2 weeks.

No mortality occurred and the 4 h-LC_{50 inhalation (powder, aerosol)}was > 5235 mg/m³. The following clinical signs were observed, some of them up to the sixth postexposure day: labored breathing patterns, irregular breathing patterns, hair coat ungroomed, piloerection, motility reduced, limp, high-legged gait, nasal discharge (serous), hypothermia, and decreased body weights. The 4 h-NO(A)EL was < 5235 mg/m³.

Slags, ferrous metal, blast furnace (ground, granulated – GGBS) do not exert acute inhalation toxicity in rats.

Results of the study: “Inhalation pulmonary toxicity and kinetics in rats” have been reviewed. Dose dependent reduction in alveolar macrophage count has been found. A cytotoxic potential of biologically available parts of GGBS under overload conditionscannot be excluded and needs clarification. The origin of trace elements and Si in different tissues and urine of control animals first needs clarification to explain the extraordinary huge interindividual variance related to some analytical parameters in control rats. Therefore, the toxicological significance of findings cannot be conclusively judged without further investigations.

Dermal

3 reports were published using the data of an exhaustive project on health and environmental safety of steelmaking slags. This project comprised 3 studies performed according to OECD TG 402 on slags, steelmaking, converter (BOS) and slags, steelmaking (SMS), and crushed stone from a quarry in the vicinity of Serra (), respectively. Fine-ground BOS, SMS and crushed stone were dosed, in their original form, at 4 g/kg bw under semi-occlusive dressing for 24 h to Wistar rats. After dosing, the patches were removed and the animals were observed for a post exposure period of 14 days. The LD₅₀was > 4000 mg/kg bw for each test material.

BOS, SMS, and the natural stone are not toxic via the dermal route. Due to the similarity of all ferrous slags, the LD₅₀can be read across to the other slags. All ferrous slags do not need to be classified as dermal toxicants. No signal word and no hazard statement are required for any ferrous slag.

Ferrous slags are almost insoluble in water and lipid phases. As a consequence, they cannot pass through the skin. The aqueous layer of the skin is not acidic enough to enable the release and uptake of ions of toxicological relevance. Systemic exposure appears to be negligible and toxicologically insignificant. Furthermore, dermal contact with natural rock - which is similar in chemical and mineral composition to slags - is a common feature of everyday life of humans. No acute toxicity as a result of dermal contact has been reported. Based on these facts, the requirement for additional tests on the dermal acute toxicity of ferrous slags is waived also in regard to animal welfare.

 

Justification for classification or non-classification

At any concentration tested, no significant toxic effect of slags on test organisms occurred, and no classification is required for acute toxicity after oral, dermal and respiratory exposure.