Manufacture of bidis - the Indian version of cigarettes - is one of the largest cottage industries in India. Bidi rollers handle 225-450 g of bidi tobacco per day and inhale tobacco dust and volatile components present in the work environment. Since tobacco is known to be mutagenic and carcinogenic, urinary cotinine was estimated in bidi rollers and control subjects as an index of tobacco-specific exposure while the concentration of urinary thioethers was determined to ascertain exposure to electrophilic moieties. Detection of cotinine in urine samples from bidi rollers with no tobacco habits indicated that occupational exposure leads to cutaneous absorption of tobacco constituents and the resultant increase in exposure to alkylating agents was evident from elevated urinary thioether levels.