Silane

Endpoint summary

Description of key information

In the key acute inhalation study (Toxic Hazard Research Unit, 1972, reliability score 2) conducted using a protocol similar to OECD Test Guideline 403 (reliability score 2) and prior to the introduction of GLP, a concentration of 9600 ppm (12611 mg/m³) silane (CAS 7803-62-5; EC No. 232-263-4) for four hours caused deaths in 4 of 10 mice. A concentration of 9600 ppm (12611 mg/m³) for 4 hours did not cause any deaths in five rats. Hence the LC50s for mice and rats were approximately 10000 ppm and >9600 ppm, respectively. There are no acute oral or dermal toxicity studies available.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study conducted during the period June 1971 to May 1972

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

other: rat and mouse

Strain:

other: CFE and CF1, respectively.

Sex:

male

Details on test animals or test system and environmental conditions:

No data.

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: nitrogen

Details on inhalation exposure:

No data.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Beckman Infrared 5-A spectrophotometer

Duration of exposure:

1 - 4 h

Concentrations:

1000, 4000, 6000, 10000 ppm

No. of animals per sex per dose:

5-50 males

Control animals:

yes

Details on study design:

No data.

Statistics:

No data.

Key result

Sex:

male

Dose descriptor:

LC50

Effect level:

> 9 600 ppm

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: based on 4/10 deaths at this concentration in mice

Key result

Sex:

male

Dose descriptor:

LC50

Effect level:

> 9 600 ppm

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: based on 0/5 deaths in rats (equivalent to >12611 mg/m³)

Mortality:

See Table 1.

Clinical signs:

other: No data.

Body weight:

No data.

Gross pathology:

No data.

Other findings:

No data.

Table 1 Summary of results for acute inhalation studies in rats and mice

Species	Nominal concentration (ppm)	Measured concentration (ppm)	Measured concentration (mg/l)	Exp. time (h)	Mortality	Time to death
Rat	1000	-	-	1.25	0/50	-
Rat	4000	-	-	1	0/5	-
Rat	10000	9600	12.6	4	0/5	-
Mouse	6000	-	-	1	0/5	-
Mouse	10000	9600	12.6	4	4/10	31 -45 h
Mouse	10000	9800	12.8	2	0/10	-

The mean weight gain of the 9600 ppm group appears to have been slightly inhibited during the first post-exposure week, but fully recovered at 14 days. No gross lesions due to treatment were observed at sacrifice. A gross pathological examination of the animals that died was not conducted.

Interpretation of results:

GHS criteria not met

Conclusions:

In an acute inhalation study conducted using a protocol similar to OECD Test Guideline 403 prior to the introduction of GLP (reliability score 2), a concentration of 9600 ppm silane for 4 hours caused deaths in 4 of 10 mice. A concentration of 9600 ppm for 4 hours did not cause any deaths in five rats. Hence the LC50s for mice and rats were approximately 10000 ppm and >9600 ppm, respectively.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

> 12 611 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There are no acute toxicity data available for oral or dermal routes. However, in accordance with Annex XI of REACH, the acute oral and dermal toxicity studies do not need to be conducted as the substance is a gas which is spontaneously flammable in air.

For the inhalation route, the key study (Toxic Hazard Research Unit, 1972, reliability score 2) was chosen in preference to other available reliable studies as it was conducted using rats, the preferred species for acute inhalation toxicity studies. In this study the highest concentration tested was restricted by the flammability of silane. Since no deaths occurred the LC₅₀ was >9600 ppm (>12,611 mg/m³).

Two other reliable studies provide supporting information for the inhalation route. In a well documented study (Omae, 1992) that was conducted using a similar protocol to OECD Test Guideline 403 (not to GLP; reliability score 2), male ICR mice were exposed to 1000 ppm silane for 1, 2, 4 and 8 hours. No mice died and no exposure-related changes in any organs were observed. Biochemical or haematological parameters affected included an increase in red blood cell counts in mice exposed for 8 hours, an increase in blood urea nitrogen in mice exposed for 1 hour and a decrease in the 8-hour exposure group, and a decreased white blood cell count after 1-hour exposure. The 4 hour LC₅₀ was greater than 1000 ppm. In another well conducted acute inhalation study (Takebayashi, 1992; reliability score 2 as no information on GLP, and only males were tested) which generally exceeded the requirements of OECD Test Guideline 403, male ICR mice were exposed to 2500, 5000, 7500, or 10000 ppm for 30 minutes (n=8), one hour, or four hours (n=12). In the one and four hour groups 12 mice were divided into two subgroups; four for a two day observation and eight for a two week observation. Only animals in the group exposed to 10000 ppm for 4 hours died (9/12; all within 24 hr). At autopsy these animals had increased relative kidney weights, renal tubular necrosis, splenic atrophy, appearance of macrophages with debris of degenerated cells in bone marrow and thymus, and inflammatory changes of the nasal mucosa. In the groups exposed for 30 minutes or one hour and sacrificed at week two, changes to the kidneys were the main effects found (tubular interstitial nephrosis in 6/8 and 7/8 animals, respectively). Following exposure to 7500 ppm (only 30-min exposure), tubular nephrosis was observed in 4/8 animals. The one and four hour exposures to 5000 ppm caused tubular interstitial nephritis in 1/8 and 2/8 animals sacrificed at week 2, respectively, and acute renal tubular necrosis in 0/4 and 1/4 animals sacrificed after two days, respectively. Concerning the 2500 ppm groups, the only effect observed was acute renal tubular necrosis in 1/4 animals exposed for 4 hours. It was concluded that the LC₅₀ was 5000-10000 ppm.

Justification for classification or non-classification

Based on the available data, silane does not require classification for acute toxicity according to Regulation (EC) 1272/2008.