The National Institute for Occupational Safety and Health has set a recommended exposure limit  of 0.1 mg/m3 over an 8-hour workday. At levels of 100 mg/m3, warfarin is immediately dangerous to life and health.It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities. Names
Warfarin is a derivative of dicoumarol, an anticoagulant originally discovered in spoiled sweet clover. Dicoumarol, in turn, is from coumarin, a sweet-smelling but coagulation-inactive chemical found in "sweet" clover and tonka beans (also known as cumaru from which coumarins name derives). The drug is marketed under many brand and generic names, including Aldocumar, Anasmol, Anticoag, Befarin, Cavamed, Cicoxil, Circuvit, Cofarin, Coumadin, Coumadine, Cumar, Farin, Foley, Haemofarin, Jantoven, Kovar, Lawarin, Maforan, Marevan, Marfarin, Marivanil, Martefarin, Morfarin, Orfarin, Panwarfin, Scheme, Simarc, Varfarin, Varfarins, Varfine, Waran, Warcok, Warf, Warfareks, Warfarin, Warfarina, Warfarine, Warfarinum, Warfen, Warfin, Warik, Warin, Warlin, and Zyfarin. Research
Long-term use of VKOR inhibitors as anticoagulation therapy was associated with lower cancer incidence. References
Further reading
Dean L (2012). "Warfarin Therapy and VKORC1 and CYP Genotype". In Pratt VM, McLeod HL, Rubinstein WS,  et al. (eds.). Medical Genetics Summaries. National Center for Biotechnology Information (NCBI). PMID 28520347. Bookshelf ID: NBK84174. External links
"Warfarin". Drug Information Portal. U.S. National Library of Medicine.
Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent stroke in people who have atrial fibrillation, valvular heart disease, or artificial heart valves. Less commonly, it is used following ST-segment elevation myocardial infarction and orthopedic surgery. It is generally taken by mouth, but may also be used intravenously.The common side effect is bleeding. Less common side effects may include areas of tissue damage and purple toes syndrome. Use is not recommended during pregnancy. The effects of warfarin typically should be monitored by checking prothrombin time (INR) every one to four weeks. Many other medications and dietary factors can interact with warfarin, either increasing or decreasing its effectiveness. The effects of warfarin may be reversed with phytomenadione (vitamin K1), fresh frozen plasma, or prothrombin complex concentrate.Warfarin decreases blood clotting by blocking an enzyme called vitamin K epoxide reductase that reactivates vitamin K1. Without sufficient active vitamin K1, clotting factors II, VII, IX, and X have decreased clotting ability. The anticlotting protein C and protein S are also inhibited, but to a lesser degree. A few days are required for full effect to occur, and these effects can last for up to five days.