Arsenic has been classified by International Agency for Research in Cancer roup I carcinogen (human carcinogen). Chronic exposure to inorganic arsenic is a potential occupational hazard. Permissible exposure limit (PEL) is 10 ug/m3 for an day (OSHA) Short-term exposure limit (STEL) is 2 ug/m3 for 15-min period (ATSDR,20o6) Biological Exposure Index (BEI) of total arsenic in urine is 35 ug/l