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 : “Smyth and Seaton  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
ACUTE TOXICITY DATA
Lethal concentration data:
|Species||Reference||LC50(ppm)||LCLo(ppm)||Time||Adjusted 0.5-hrLC (CF)||Derivedvalue|
|Carpenter et al. 1949Smyth and Seaton 1940
Smyth and Seaton 1940
Smyth and Seaton 1940
|4 hr6 hr
|2,000 ppm (2.0)1,610 ppm (2.3)
1,375 ppm (0.79)
1,872 ppm (1.6)
|200 ppm161 ppm
Lethal dose data:
|Species||Reference||Route||LD50(mg/kg)||LDLo(mg/kg)||Adjusted LD||Derived value|
|Rat||Carpenter et al. 1949||oral||6,270||—–||5,068 ppm||507 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 ppmBasis 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 . Ethyl silicate. In: Hygienic guide series. Am Ind Hyg Assoc J 29:624-626.
2. Carpenter CP, Smyth HF Jr, Pozzani UC . 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 . 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.