Man-made vitreous (silicate) fibres with random orientation with alkaline and alkali earth oxides (Na2O+K2O+CaO+ MgO+BaO) content greater than 18% by weight and fulfilling one of the CLP Regulation Annex VI Note Q conditions

Endpoint summary

Description of key information

For Note Q man-made vitreous fibres (MMVFs), inhalation is the key route of exposure. By the physical properties of these fibres, acute dermal toxicity upon exposure to Note Q MMVFs is not of concern. Oral exposure to Note Q MMVFs is an unlikely route of human exposure; thus, acute oral toxicity is also not of concern.

No studies specifically addressing the acute inhalation toxicity potential of Note Q MMVFs were identified. Nevertheless, there are long-term studies with inhalation exposure of up to 2 years on Note Q MMVFs available. In the study by Hesterberg et al. (1993), Fischer 344 male rats were exposed to the Note Q-fulfilling MMVF 11 to the concentrations of 3, 16 and 30 mg/m³ using nose-only inhalation chambers for 6 hr/day, 5 days/week for 24 months. No difference in mortality was observed between the MMVF 11-exposed rats and filtered air (negative control)-exposed rats at the end of the study. Another study by Kamstrup et al. (2001) used the same chronic exposure design as the Hesterberg et al. (1993) study but tested another Note Q MMVF (MMVF 34/HT at 30 mg/m³) on Fischer 344 male rats. No difference in mortality was observed between MMVF 34-exposed and filtered air-exposed rats at the end of the study. It should be mentioned that 30 mg/m³ has been tested and demonstrated to be the maximum tolerated dose (MTD) for MMVFs such that exposure above this MTD would lead to nonspecific lung pathology due to overload of the lung (see Hesterberg et al. 1996. Fundam Appl Toxicol, 32, 31-44).

The chemical composition of the Note Q MMFs also does not lead to any concern related to acute toxicity. Submitted data of the REACH registration dossier indicated minimal to no indication of acute toxicity (no CLP classification). The majority of tests for some of the individual key components of Note Q MMVFs such as silicon oxide, aluminium oxide, diboron trioxide and calcium oxide were performed according to the OECD test guideline 403 for acute inhalation toxicity (please refer to the respective registration dossiers) .

Altogether, there is consistent evidence showing no concern of acute inhalation toxicity of Note Q MMVFs based on the lack of lethal effects seen in chronic inhalation studies of Note Q MMVFs as well as the lack of acute toxicity of some of the main chemical components of these fibres. Thus, Note Q MMVFs do not warrant classification for acute toxicity taking a weight-of-evidence approach.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the physicochemical and toxicological properties suggest no potential for a significant rate of absorption through the skin

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Justification for classification or non-classification

MMVF note Q fibres are inorganic fibres, whose physicochemical properties suggest a low potential to cross biological membranes. Thus MMVF note Q fibres have a low potential for absorption into the body through the skin, the airways and the gastrointestinal tract. MMVF note Q fibres are assessed to have no acute toxicity by skin contact or if ingested. Long-term inhalation studies showed that MMVF note Q fibres caused minimal collagen deposition in the lungs and did not induce fibrotic or neoplastic changes in the lungs or in pleura. Furthermore, in a comparable to guideline study, the mortality rate in the exposed animals was the same as for the control animals. Based on these studies MMVF note Q fibres are assessed to have no acute toxicity by inhalation. MMVF note Q fibres shall not be classified as an acute toxicant according to the criteria in Council Directive 67/548/EEC and Regulation (EC) 1272/2008.