INHALATION TOXICOLOGY OF GLYCOLIC ACID

Abstract

Glycolic acid (hydroxyacetic acid; CAS no. 79-14-1) was tested for its inhalation toxicity to rats following both single and repeated exposures. The LC50 for single 4-h exposures was 7.1 mg/L, with all rats surviving exposures of 4.0 mg/L. The material is considered slightly toxic following acute inhalation. Groups of male rats were exposed by inhalation to either 0 (control), 0.16, 0.51, or 1.4 mg glycolic acid/ L, 6 h/day, 5 days/wk for 2 wk. The highest level tested was not well tolerated, with exposures being discontinued after eight exposures, and seven rats were sacrificed following labored breathing, lung noise, nasal and ocular discharge, and severe weight loss. Clinical pathology changes included decreases in serum protein, increases in both ALT and ALP, and decreases in urine volume and pH, indicative of altered hepatic function. These changes were reversible in the 3 surviving rats allowed a 10-day-off treatment recovery period. Pathologic changes in this group included diffuse hepatocellular degeneration and thymic atrophy. One of 10 rats exposed to 0.51 mg/L died after 10 exposures. The same in-life observations as seen at 1.4 mg/L were made in this group with both the incidence and severity diminished. Clinical and microscopic pathology indicated liver and thymic damage, with clinical pathology changes being reversible. The tissues of the upper respiratory tract appeared normal at sacrifice but were not examined microscopically. The only effect seen at 0.16 mg/L was a very mild, diffuse hepatocellular degeneration seen in 1 of 10 rats examined 14 days postexposure. Thus, although not specifically determined, this concentration approached a no-observed-adverse-effect level.