Toxicity of methoxyacetic acid in rats.

Male Fischer 344 rats were given eight daily doses of 0, 30, 100 or 300 mg/kg methoxyacetic acid by gavage. The high dose resulted in decreased body weight, severe degeneration of testicular germinal epithelium, decreased size of the thymus with depletion of thymic cortical lymphoid elements, and reductions in bone marrow cellularity resulting in depressions of red blood cell counts, hemoglobin concentration, packed cell volume, and white blood cell counts. Some of these observations were apparent to a lesser degree in rats given 100 mg/kg. The low dose produced no apparent effects during the course of the study. These toxicological properties of methoxyacetic acid are remarkably similar to ethylene glycol monomethyl ether (EGME), and the adverse effects of EGME in rats are probably the result of in vivo bioactivation of EGME to methoxyacetic acid.