Arsenic is an environmental pollutant and is known to induce toxicity. Arsenic acts on cells through a variety of mechanisms, influencing numerous signal transduction pathways. It induces a variety of cellular effects such as apoptosis, growth inhibition, promotion or inhibition of differentiation and angiogenesis. Arsenic has been associated with cancers of the skin, bladder, lung, kidney, and liver as well as with noncancerous conditions, diabetes and hepatopathy. However, arsenic trioxide (ATO) was reported to induce remission in patients with acute promyelocytic leukemia (APL). The anticancer efficiency of ATO was not restricted to APL; however, it has been extended to many solid tumors, including liver, cervical, prostate, lung, esophagus, and bladder tumors. Therefore, in this study, a number of previous studies are summarized that demonstrate arsenic-induced toxicity, including carcinogenesis and anticancer activity in vitro and in vivo. The arsenic metabolism that is involved in arsenic-induced toxicity is also discussed.

Abstract
 INTRODUCTION
 ARSENIC METABOLISM
 ARSENIC-INDUCED TOXICITY
 CARCINOGENESIS
 ANTICANCER ACTIVITY
 CONCLUSION
 REFERENCES

• Soohee Kim(Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University) Corresponding Author
• Doug-Young Ryu(Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University)