This method is designed to evaluate changes in tyrosinase activity after exposure to a test material using tyrosinase derived from either human melanocytes or the mushroom species agaricus bisporus. For the assay, the source of tyrosinase is combined with either the test material, cinnamic acid (positive control) or vehicle (untreated control).  L-DOPA will then be added to the mixture and tyrosinase activity will be determined via a colorimetric assay measuring the conversion of L-DOPA to DOPA chrome.