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Ethyl silicate

May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS number: 78–10–4

NIOSH REL: 10 ppm (85 mg/m3) TWA

Current OSHA PEL: 100 ppm (850 mg/m3) TWA

1989 OSHA PEL: 10 ppm (85 mg/m3) TWA

1993-1994 ACGIH TLV: 10 ppm (85 mg/m3) TWA

Description of Substance: Colorless liquid with a sharp, alcohol-like odor.

LEL:. . Unknown

Original (SCP) IDLH: 1,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the following statements by AIHA [1968]: "Smyth and Seaton [1940] reported that 1,740 ppm in dry air caused the first guinea pig death in 15 minutes, while at 1,170 ppm the first death was in 2 hours. In the presence of 70% humidity, effects were less pronounced, presumably because part of the ethyl silicate was hydrolyzed."

Short-term exposure guidelines: None developed


Lethal concentration data:






Adjusted 0.5-hr





G. pig

G. pig

G. pig

Carpenter et al. 1949

Smyth and Seaton 1940

Smyth and Seaton 1940

Smyth and Seaton 1940









4 hr

6 hr

15 min

2 hr

2,000 ppm (2.0)

1,610 ppm (2.3)

1,375 ppm (0.79)

1,872 ppm (1.6)

200 ppm

161 ppm

138 ppm

187 ppm

Lethal dose data:







Adjusted LD

Derived value
RatCarpenter et al. 1949oral6,270-----5,068 ppm507 ppm

Other animal data: It has been stated that 2,000 ppm is about the maximum exposure for 60 minutes without the production of serious disturbances in guinea pigs and rats; 500 ppm is the maximum exposure for several hours without causing serious effects [Smyth and Seaton 1940].

Human data: Exposure to a concentration of 1,200 ppm caused lacrimation and 250 ppm caused irritation of the eyes and nose [Smyth and Seaton 1940]. It has been stated that 700 ppm is probably intolerable for more than 30 minutes [Smyth and Seaton 1940].

Revised IDLH: 700 ppm

Basis for revised IDLH: The revised IDLH for ethyl silicate is 700 ppm based on acute inhalation toxicity data in humans [Smyth and Seaton 1940].


1. AIHA [1968]. Ethyl silicate. In: Hygienic guide series. Am Ind Hyg Assoc J 29:624-626.

2. Carpenter CP, Smyth HF Jr, Pozzani UC [1949]. The assay of acute vapor toxicity, and the grading and interpretation of results on 96 chemical compounds. J Ind Hyg Toxicol 31:343-346.

3. Smyth HF Jr, Seaton J [1940]. Acute response of guinea pigs and rats to inhalation of the vapors of tetraethyl orthosilicate (ethyl silicate). J Ind Hyg Toxicol 22(7):288-296.

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