case of overdoses, the storage of GSH will not be enough for NAPQI detoxication, thereby resulting in acute liver injury. Other oxidoreductases Oxidoreductases are enzymes that catalyze the reactions that involve the transfer of electrons. Methanol in itself is toxic due to its central nervous system depression properties, but it can be converted to formaldehyde by alcohol dehydrogenase and then converted to formic acid by aldehyde dehydrogenase, which are significantly more toxic. Formic acid and formaldehyde can cause severe acidosis, damage to the optic nerve, and other life-threatening complications. Ethylene glycol (common antifreeze) can be converted into toxic glycolic acid, glyoxylic acid and oxalic acid by aldehyde dehydrogenase, lactate dehydrogenase (LDH) and glycolate oxidase in mammalian organisms. The accumulation of the end product of the ethylene glycol mechanism, calcium oxalate, may cause malfunction in the kidney and lead to more severe consequences. Heavy metals Lead or zinc-based paints and dust are commonly found in old buildings. These dust and paint are dangerous for exposure to children and adults. Their components of lead, zinc, and copper might cause acute diseases. In adults, most of them are affected by occupational exposure, such as welding, painting, or in industries. When a person is exposed to heavy metals for a long period of time, the heavy metals start accumulating in the body, leading to diseases like gastrointestinal and kidney dysfunction, nervous system disorders, skin lesions, vascular damage, immune system dysfunction, birth defects, and cancer. Other examples Other examples of toxication by enzymatic metabolism include: Conversion of secondary amines in the stomach into carcinogenic nitrosamines via NO pathway. Nicotine into the nitrosated carcinogenic NNK (4-(methylnitrosamino)- 1-(3-pyridyl)-1-butanone) in the lung. Benzo[a]pyrene into the carcinogenic benzo[a]pyrene diol epoxide (BP-7,8-dihydrodiol-9,10-epoxide) Hypoglycin A into the highly toxic MCPA-CoA Toxication by abiotic chemical reactions Increases in toxicity can also be caused by abiotic chemical reactions. Non-living elements affect the abiotic chemical reactions. Anthropogenic trace compounds (ATCs) have potential toxicity to the organisms in aquatic system. Arsenic contamination in drinking water can be chemically toxic. The uptake and metabolism of arsenic may result the damage to body. When organic arsenic is converted into more toxic inorganic arsenic, it causes carcinogenesis, cytotoxicity (toxic to cells) and genotoxicity (causing mutations in genes). See also Chelation therapy Detoxification References Pharmacokinetics Biodegradation