The aim of the study is to evaluate the effectiveness in removing chemical exposure on hand, the investigators compare removal efficiency of Di-(2-ethylhexyl)phthalate (DEHP) on hands by hand washing with soap and water vs. water only. In two three-day N-of-1 trials, residual DEHP was measured in a single female adult who washed exposed hands with soap-and-water or water-only. Subsequently, a crossover study was performed by randomly assigning another 28 subjects equally to wash with soap-and-water or with water-only, and then each one received the other treatment 24 hrs later.