Trichlorosilane

Endpoint summary

Description of key information

In the key acute oral toxicity study for trichlorosilane, conducted according to a protocol similar to the now-deleted OECD Test Guideline 401 but pre-dating GLP, an LD50 value for male albino rats was concluded to be 1.03 (0.89 to 1.21) g/kg (equivalent to 1030 mg/kg bw/day) (Mellon Institute, 1948).

No key acute inhalation or dermal toxicity studies are available.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

No information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Basic information is available. Only one sex was tested.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Principles of method if other than guideline:

other

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

not specified

Sex:

male

Route of administration:

oral: gavage

Vehicle:

corn oil

Doses:

0.795, 1.0, 1.26, and 1.58 g/kg (as a 10% dilution in corn oil)

No. of animals per sex per dose:

10 males/dose

Control animals:

no

Details on study design:

14-day post observation period; body weight was monitored

Statistics:

The LD50 was calculated by the method of Thompson.

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

1 030 mg/kg bw

Based on:

test mat.

95% CL:

> 890 - < 1 210

Mortality:

Mortalities of 2, 5, 7, and 9 animals out of 10 were reported for the male rats dosed on 0.795, 1.00, 1.26, and 1.58 g/kg bw, respectively.

Clinical signs:

other: No information available.

Gross pathology:

Direct injury to the gastrointestinal tract was the cause of death. The stomach and intestines haemorrhaged and where the stomach contacted the liver and kidney the latter organs had a cooked appearance.

MALES:

Dosage: 1.58 g/kg

Dead/Dosed: 9/10

Weight Change (g) in 14 days: +37 grams

Dosage: 1.26 g/kg

Dead/Dosed: 7/10

Weight Change (g) in 14 days: +38 grams to +60 grams

Dosage: 1.00 g/kg

Dead/Dosed: 5/10

Weight Change (g) in 14 days: +3 grams to +59 grams

Dosage: 0.795 g/kg

Dead/Dosed: 2/10

Weight Change (g) in 14 days: -14 grams to +38 grams

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

In an acute oral toxicity study, conducted to a protocol similar to OECD Test Guideline 401 but pre-GLP, trichlorosilane was dosed as a 10% v/v dilution in corn oil. An LD50 for male albino rats was concluded to be 1030 mg/kg bw (890 to 121 mg/kg bw). No clinical observations were specified. Observations from necropsy indicated that direct injury to the gastrointestinal tract was the cause of death. The stomach and intestines haemorrhaged and where the stomach contacted the liver and kidney, the latter organs had a cooked appearance.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 030 mg/kg bw

Quality of whole database:

Klimish score of 2.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

In the key acute oral toxicity study for trichlorosilane, conducted according to a protocol similar to the now-deleted OECD Test Guideline 401 but pre-dating GLP, an LD50 value for male albino rats was concluded to be 1030 mg/kg bw (890 to 121 mg/kg bw). In the study, 10 male rats per group and dose were given single oral (gavage) administration of trichlorosilane, 10% v/v dilution in corn oil, at doses of 0.795, 1.0, 1.26, and 1.58 g/kg. The animals were observed for 14 days after oral administration. At the end of the observation period the animals were subject to necropsy. Mortalities of 2 out of 10 (2/10), 5/10, 7/10, and 9/10 animals were reported for the male rats dosed at 0.795, 1.00, 1.26, and 1.58 g/kg bw, respectively. No clinical observations were specified in the study report. Observations from necropsy indicated that direct injury to the gastrointestinal tract was the cause of death. The stomach and intestines haemorrhaged and where the stomach contacted the liver and kidney, the latter organs had a cooked appearance (Mellon Institute, 1948).

In a supporting acute inhalation toxicity study, conducted according to OECD Test Guideline 403 and in compliance with GLP, a combined LC50 value for males and females was determined to be 2717 ppm with a 95% confidence limits of 2388-3374 ppm. Clinical signs seen in all groups included nasal crust, rough coat, sores on the face and corneal opacity. Mouth breathing was seen in all groups except in the 3770 ppm group. Other less frequently observed signs included rales, ocular discharge and an absent nasal septum for one 3770 ppm male. These data are no longer considered to be reliable due to:

(1) Nose-only inhalation methods are poorly suited for investigating the inhalation hazards of corrosive noxious substances like chlorosilanes because the animals can often reduce their exposure by altering their position so as to limit breathing in of the test atmosphere;

(2) The nose-only chamber (cones) produces additional stress on the animals that can contribute to their overall health, potentially contributing to morbidity;

(3) A nominal value for the HCl exposure was not obtained. Exposure concentration was based solely on the IR method

(4) Repeating the LC50determinations in a whole-body inhalation system which does not allow the animals to avoid/reduce breathing in of the test atmosphere produced similar but not identical LC50 values.  

The LC50 value obtained in the nose-only system was inconsistent with available data on chlorosilanes

For substances as hydrochloride, the LC50 value obtained in the nose-only system was clearly inconsistent with all the available data on chlorosilanes (Jeanet al., 2006). Therefore, the study is not considered as an appropriate key study for the acute inhalation endpoint (Dow Corning Corporation, 1987).

 

In another supporting acute inhalation study, not conducted according to any OECD Test Guideline and not in compliance with GLP, a test concentration of 1000 ppm without lethal effects was determined (Bushy Run Research Centre, 1986).

 

In an acute inhalation toxicity study, not conducted according to OECD Test Guideline or GLP, an exposure to the substantially saturated vapour of trichlorosilane for 5 minutes caused death in 6 out of 6 animals. The study did not meet current guideline requirements due to lack of detail on exposure, test animals, test substance and test conditions. However, it adds weight of evidence for inhalation toxicity (Mellon Institute, 1951).

In an acute inhalation toxicity study, not conducted according to OECD Test Guideline or GLP, an exposure to trichlorosilane at vapour concentrations of 1000 ppm or 500 ppm for 4 hours caused death in 3 of 6 rats and in 1 of 6 rats, respectively. The study did not meet current guideline requirements due to lack of detail on exposure, test animals, test substance and test conditions. However, it adds weight of evidence for inhalation toxicity (Mellon Institute, 1951).

In an acute inhalation toxicity study, not conducted according to OECD Test Guideline or GLP, an LCLo value was determined to be 1000 ppm. No further details are available (IUCLID, 2000a).

 

In a supporting acute inhalation toxicity study, not conducted according to OECD Test Guideline or GLP, a 2-hour LC50 value of 1.5 mg/l in mouse was reported in IUCLID 2000. No further details are available (IUCLID 2000b).

Justification for classification or non-classification

Trichlorosilane is formally classified in Annex VI of Regulation (EC) No 1272/2008 for acute oral toxicity Category 4 and acute inhalation (vapour) toxicity Category 4.

However, in line with the Committee for Risk Assessment Opinion adopted on 11th June 2020, the resulting harmonised classification in Annex VII of Regulation (EC) No 1272/2008 will be acute oral toxicity Category 4, H302: “Harmful if swallowed” and acute inhalation toxicity (vapour) Category 3, H331: “Toxic if inhaled” if accepted by COM.