Complex sentence: The renal toxicity of ethylene glycol is caused by direct cytotoxic effects of the glycolate metabolite, in addition accumulation of calcium oxalate crystals in the kidneys may cause kidney damage.
Split into simpler sentences: The renal toxicity of ethylene glycol is caused by direct cytotoxic effects of the glycolate metabolite. In addition, accumulation of calcium oxalate crystals in the kidneys may cause kidney damage.