Dimethoxydiphenylsilane

Endpoint summary

Description of key information

Acute oral toxicity (OECD TG 401, GLP): LD50 > 2000 mg/kg bw
Acute inhalation toxicity (similar to OECD TG 403): LD50 > 0.42 mg/l (nominal concentration)
Acute dermal toxicity: data waiver according to Column 2 of REACH Annex VIII

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating dose

Value:

2 000 mg/kg bw

Quality of whole database:

The study was conducted according to OECD TG 401, and in compliance with GLP.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating conc.

Value:

420 mg/m³ air

Quality of whole database:

The study was well documented and meets generelly accepted scientific principles, but was not conducted in compliance with GLP. The study was carried out prior to the publication of the OECD test guidelines, but the experimental design is equivalent or similar to that described in the OECD TG 403.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Two acute oral toxicity studies and one acute inhalation toxicity study are available for assessment of the acute toxicity of dimethoxydiphenylsilane.

Acute oral toxicity:

In the key study for acute oral toxicity male and female Hsd/Cpb:WU rats (5 per sex) were dosed with 2000 mg/kg bw of the test substance by oral gavage (Hüls AG, 1995a). The study was performed according OECD TG 401 and in compliance with GLP regulations. Within 72 hours 2/5 males and 1/5 females were found dead. The strongest clinical signs were noted 24 h (females) or 6 to 48 h (males) after dosing. Clinical signs observed were amongst others sedation and decreased motility, ataxia, hypothermia, altered breathing, and moribund conditions. In addition delayed body weight gains were observed. Gross pathology revealed alterations of the liver (blotchy, cirrhosis-like), stomach (reddened epithelium, isolated bleedings) and kidney (dot-shaped, slight pelvic extension). Haematomas in the cranial vault and haemorrhagic fluids in the thoracic cavity were observed in males. In all animals adrenals were darkly coloured, the pancreas was white and bloodless, and the caecum content was hard and solid. The urinary bladder was bulging, and in males the genitals were decreased. In the lungs of both males a strong hyperaemia was noted. None of the surviving animals showed test material related gross pathologic changes. Livers and kidneys of all three animals which died within 72 hours after test material application were microscopically examined. The specific substance related findings were degeneration of the kidney cortex and non-degenerative steatosis of the liver. In conclusion, the LD50 was found to be > 2000 mg/kg bw for both males and females. Hence, classification for acute oral toxicity according to 67/584/EEC and EC/1272/2008 is not warranted.

A second oral gavage study equivalent to OECD TG 401 (no GLP) supports these findings (Hazleton, 1980a). Male and female Sprague-Dawley rats were treated with the test substance (1000, 2000, and 4000 mg/kg bw: 5 males and 5 females each; 2500 and 7500 mg/kg bw: 5 males each; 3000 and 3500 mg/kg bw: 5 females each). One female at 2000 mg/kg bw, four males at 2500 mg/kg bw, three females at 3000 mg/kg bw, four females at 3500 mg/kg bw, four males and four females at 4000 mg/kg bw, and five males at 7500 mg/kg bw died during the study. Clinical observations consisted of depression, prostration, abnormal respiration, and tremors. No gross pathology findings were noted for animals surviving to termination of the study. Gross pathology findings for animals found dead consisted of discolouration of the lungs, liver, stomach, kidneys, and spleen; distension of the stomach, intestines, and urinary bladder; an irregularly shaped spleen; material or fluid in the stomach or intestines; and thick and thin stomach walls. In conclusion, the LD50 was found to be 2613 mg/kg bw for males and 2736 mg/kg bw for females, respectively.

Acute inhalation toxicity:

Acute inhalation toxicity was assessed in a 4 -hour acute inhalation toxicity study with male and female Sprague-Dawley rats equivalent to OECD TG 403 but not in compliance with GLP. Five animals per sex were exposed whole-body to test substance vapour (0.42 mg/l; no analytical verification) for 4 h. No mortality occured and no test material related effects on clinical signs, behaviour, and body weights were observed. Gross pathology revealed increased frequency of enlarged deep cervical and mandibular lymph nodes in treated rats relative to controls. A LD50 of > 0.42 mg/l air for both males and females was deduced (Hazleton, 1980b).

Acute dermal toxicity:

In accordance with Column 2 of REACH Annex VIII, the acute toxicity study via the dermal route (required in Section 8.5.2 of REACH Annex VIII) does not need to be conducted as reliable data via the oral and inhalation routes are available.

Justification for classification or non-classification

The available data on acute oral toxicity of the test substance do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.