3-Aminopropyltriethoxysilane

3-Aminopropyltriethoxysilane (APTES) has been tested for acute toxicity by the oral, dermal, and inhalation routes of exposure.  Acute oral LD50s in rats range from 1570 to 3650 mg/kg bw.  The dermal LD50 is 4.29 g/kg bw and the 4-hour inhalation LC50 of the hydrolysate is greater than 7.35 mg/L.  Six hours of exposure to substantially saturated vapor of APTES did not kill any of the 5 male or female rats (LT50 > 6 hours). The kidney is a target organ for toxicity for oral and dermal exposures.

APTES is severely irritating to the skin and eyes. In a Buehler study in guinea pigs, 7/30 animals showed a skin sensitization response.  The hydrolysis products of this material do not elicit a sensitization response in a guinea pig maximization test.  

Repeated inhalation exposure of rats to 147 mg/m3 of APTES hydrolysate respirable aerosol for four weeks produced squamous metaplasia and foci of minimal granulomatous laryngitis. No systemic toxicity was observed in rabbits after 9 repeated dermal doses of 17 or 84 mg/kg bw/day or three repeated dermal doses of 126 mg/kg bw/day of APTES; the site of contact NOAEL is less than 17 mg/kg bw/day. The no-observed-adverse-effect level (NOAEL) of APTES in a 90-day oral (gavage) study with rats was 200 mg/kg bw/day.  

APTES has been tested in several bacterial reverse mutation/Ames assays,  in vitro V79 hamster lung cell and Chinese hamster fibroblast chromosome aberration assays, two Chinese hamster ovary cell HGPRT gene mutation assays, and an  in vivo mouse micronucleus assay.  In vivo and  in vitro screening assays have not revealed any
evidence of genotoxic potential.

At the highest dose-level (600 mg/kg/day) in a 90 day oral gavage study in rats, no effects were seen on parameters of oestrus cycle and spermatogenesis or reproductive organs. The NOAEL for developmental effects has been identified for APTES following exposure via oral (gavage) in rats, with a value of 100 mg/kg bw/day, the NOAEL for maternal toxicity based on deaths and ulceration of the GI tract is <0.5 mL/kg