Atrazine is a broad-leaf, pre-emergence herbicide. Eighty million pounds are applied to soils annually in the United States, more than any other herbicide. Atrazine is the leading member of a class of triazine ring-containing herbicides that includes simazine and terbuthylazine. The Triazine Metapathway Map contains additional information on triazine metabolism. A number of different bacteria have been identified that are capable of metabolizing atrazine to ammonia and carbon dioxide. Atrazine biodegradation has been found to occur via several different pathways that funnel into cyanuric acid metabolism. A gene region from Pseudomonas sp. strain ADP encoding atrazine degradation enzymes has been cloned and characterized. The initial hydrolytic dechlorination of atrazine to hydroxyatrazine ([http://www.ncbi.nlm.nih.gov/pubmed/7574646|de Souza et al., 1995]) is an animated reaction. Two enzymes belonging to the amidohydrolase protein family catalyze the sequential removal of ethylamine and isopropylamine ([http://www.ncbi.nlm.nih.gov/pubmed/9055410|Boundy-Mills et al., 1997] and [http://www.ncbi.nlm.nih.gov/pubmed/9422605|Sadowsky et al., 1998]). Degradation by Rhodococcus sp. strain N186/21 is initiated by oxidative removal of either the ethyl or isopropyl group ([http://www.ncbi.nlm.nih.gov/pubmed/7646049|Nagy et al., 1995]). Deethylatrazine undergoes a second oxidative removal of the isopropyl group. Hydrolytic removal of s-triazine ring substituents from deisopropylatrazine and deisopropyldeethylatrazine yields cyanuric acid.