SAFETY ASSESSMENT OF LACTATE ESTERS

Lactate esters have an oral LD50 greater than 2000 mg/kg and the inhal ation LC50 is generally above 5000 mg/m(3) and they may be potential e ye and skin irritants, but not skin sensitizers. No evidence of terato genicity or maternal toxicity was observed in an inhalation (2-ethylhe xyl-L-lactate) or dermal study (ethyl-L-lactate). Subacute inhalation studies have been conducted at concentration up to 600 mg/m(3) or high er on four lactate esters (ethyl, n-butyl, isobutyl, and 2-ethylhexyl- L-lactate). Degenerative and regenerative changes in the nasal cavity were noted in all studies. The NOAEL in ethyl, n-butyl, and isobutyl-L -lactate vapor studies was 200 mg/m(3). For aerosoI exposure, 2-ethylh exyl-L-lactate, the most toxic of the lactates, minimal damage to the nasal epithelium was noted at 75 mg/m(3) with vapor being slightly les s toxic than the aerosol. Lactates do not appear to cause systemic tox icity, except at very high concentrations (1800 mg/m(3) or higher). Th ese systemic effects may be secondary to severe irritation seen at hig h doses. Sensory irritation tests suggest that a vapor exposure Limit of 75 mg/m3 (similar to 15 ppm) should prevent irritation in humans an d therefore an occupational exposure level for vapor of 75 mg/m3 is re commended. However, aerosol exposure should be kept as low as possible . The low vapor pressure of the higher molecular weight esters would t end to keep vapor exposure low and the odor of lactate esters serves a s a warning of exposure. These lactate esters are readily biodegradabl e, suggesting little concern from an environmental point of view. (C) 1998 Academic Press.