ii CRESOLS NOTE TO THE READER The Priority Data

The Priority Data Needs documents are intended to characterize substance-specific priority data needs determined via the ATSDR Decision guide for identifying substance-specific data needs related to toxicological profiles (54 Federal Register 37618, September 11, 1989). The identified priority data needs reflect the opinion of the Agency, in consultation with other federal programs, of the research necessary for fulfilling its statutory mandate under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (Superfund) or CERCLA. They are not intended to represent the priority data needs for any other program. I. Executive Summary Cresols are included in the priority list of hazardous substances identified by ATSDR (ATSDR 2007a). This list contains substances that have been identified at National Priorities List (NPL) sites and determined to pose a human health risk based on (1) known or suspected human toxicity, (2) frequency of occurrence at NPL sites or other facilities, and (3) the potential for human exposure to the substance. An updated Toxicological Profile for Cresols was published by ATSDR in September 2008. Three types of closely related cresols exist: ortho-cresol (o-cresol), meta-cresol (m-cresol), and para-cresol (p-cresol). Pure cresols are colorless chemicals, but they may be found in brown mixtures such as creosote and cresylic acids (e.g., wood preservatives). Because these three types of cresols are manufactured separately and as mixtures, they can be found both separately and together. Cresols can be either solid or liquid, depending on how pure they are; generally, pure cresols are solid, while mixtures tend to be liquid. Cresols have a medicinal odor and when dissolved in water, they give it a medicinal smell and taste. All cresol isomers and mixtures are very soluble in alcohol, chloroform, ether, benzene, acetone, and water. Cresols evaporate more slowly than water with a vapor pressure ranging from 0.11 to 0.30 mm Hg. Aqueous solutions of cresols do not readily volatilize from water with a Henry's law constants ranging from 1.2x10-6 to 7.92x10-7 m 3 /mol. Cresols are natural products that are present in many foods and in animal and human urine. They are also present in wood and tobacco smoke, crude oil, and coal tar. In addition, cresols can also be manufactured and used as disinfectants and deodorizers, to dissolve substances, and as starting chemicals for making other chemicals. According to the 2005 Directory of Chemical Producers, 2 CRESOLS cresols are currently produced by five manufacturers in New York, Pennsylvania, Illinois, …