poorly soluble crystals which can cause kidney failure (see Analysis section above). Safety Cyanuric acid is classified as "essentially nontoxic". The 50% oral median lethal dose (LD50) is 7700 mg/kg in rats. However, when cyanuric acid is present together with melamine (which by itself is another low-toxicity substance), it will form an insoluble and rather nephrotoxic complex, as evidenced in dogs and cats during the 2007 pet food contamination and in children during the 2008 Chinese milk scandal cases. Natural occurrence Impure copper salt of the acid, with the formula Cu(C3N3O3H2)2(NH3)2, is currently the only known isocyanurate mineral, called joanneumite. It was found in a guano deposit in Chile. It is very rare. References External links Oregon Veterinary Medical Association (OVMA) Pet Food Contamination Page – News and developments updated regularly Lactims Triazines Imides Triketones Isocyanuric acids