Hydroxytrimethylsilane

Endpoint summary

Description of key information

In an acute oral toxicity study conducted using a protocol comparable to the now deleted OECD 401, but not to GLP (Bayer, 1985), the LD50 for trimethylsilanol was 3.5 ml/kg bw (2835 mg/kg bw based on a density of 0.81 g/cm3) in rats.

In an acute inhalation study conducted to OECD 403 and to GLP (WIL, 2007), the 4 hour LC50 of trimethylsilanol was 3151 ppm (11.8 mg/l) in rats. There are no acute dermal toxicity studies for trimethylsilanol.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 835 mg/kg bw

Quality of whole database:

The key study was conducted to the now deleted OECD Test Tuideline 401, but there was no information on GLP compliance.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

11 800 mg/m³

Quality of whole database:

The key study was conducted to OECD Test Guideline 403 and in compliance with GLP.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

In an acute oral toxicity study conducted using a protocol comparable to the now deleted OECD 401, but not to GLP (Bayer, 1985), the LD₅₀ for trimethylsilanol was 3.5 ml/kg bw (2835 mg/kg bw based on a density of 0.81 g/cm³) in rats (0, 0, 10, 40, 70 and 100% mortality at 0.5, 1.0, 2.0, 3.1, 5.0, 6.3 ml/kg bw, respectively). There was a general deterioration in the animals' health, anaesthesia, lateral positioning and ruffled fur. All surviving animals appeared symptom-free after ten days.

In an acute inhalation study conducted to OECD 403 and to GLP (WIL, 2007), the 4 hour LC₅₀ of trimethylsilanol was 3151 ppm (11.8 mg/l) in rats (total mortality was 0/10, 8/10 and 10/10 animals for the 1824, 3517 and 7443 ppm groups, respectively). Significant clinical observations for the surviving animals during the 14-day post-exposure observation period consisted of staining on the urogenital area, decreased respiration, shallow respiration, rales, hypoactivity, prostration, ataxia, lacrimation of the eyes, partial closure of the eyes, decreased defecation, decreased urination, and opacity of the eyes. All surviving animals in the 1824 and 3517 ppm groups were considered normal by study days 2 and 5, respectively. Internal macroscopic findings noted for animals that died prior to the scheduled necropsy were dark red areas on the lungs, dark red discoloration of the lungs and clear fluid contents in the uterus for the 1824 and 3517 ppm groups; red discoloration of the corticomedullary junction in the kidneys, dark red discoloration of the liver, accessory spleen and cysts on the ovaries for the 3517 ppm group; and dark red discoloration of the adrenal glands, distended urinary bladder, opacity of the eyes and dark red areas on the urinary bladder for the 1824 ppm group. At the scheduled necropsy, white areas on the spleen, clear fluid contents in the uterus and pale lungs were noted in the 1824 ppm group. There were no other macroscopic findings for animals at the scheduled necropsy.

There are no acute dermal toxicity studies for trimethylsilanol.

Justification for classification or non-classification

Based on the available data trimethylsilanol is not classified for acute toxicity (lethality) following a single exposure via the oral route under Regulation (EC) 1272/2008. However, for the inhalation route it is classified as Category 4, with the hazard statement 'H332: Harmful if inhaled'.