2004 Edition of the Drinking Water Standards and Health Adv isories 2004 Edition of the Drinking Water Standards and Health Advisories EPA 822-R-04-005Office of WaterU.S. Environmental Protection AgencyWashington, DCWinter 2004Recycled/Recyclable Printed on paper that contains at least 50% recy cled fiber. The Drinking Water Standards and Health Adv isories tables are revised periodically by EPA’s Office of Water on an “as needed” basis. The following information should be kept in mind when using the Tables: Reference dose (RfD) values are updated to reflect the values in the Integrated Risk Information System (IRIS), and the Drinking Water Equivalent Level (DWEL) has been calculated accordingly. Thus, both the RfD and DWEL in the Tables differ from the values in the Health Advisory document if the IRIS RfD is more recent than the Health Advisory document value. RfD values from IRIS that differ from the values in the Health Advisory documents are presented in BOLD type. For unregulated chemicals with a new IRIS RfD, the lifetime Health Advisory was calculated from the DWEL using the relative source contribution value published in the Health Advisory. For regulated chemicals, where the revised lifetime value differed from the Maximum Contaminant Level Goal (MCLG), no lifetime value was provided in the Table. For regulated chemicals, the cancer group designation and 10-4 cancer risk reflect the status at the time of regulation. For unregulated chemicals, the cancer group designation or cancer classification and 10-4 cancer risk reflect the values presently on IRIS. New IRIS cancer designations and 10-4 cancer risk values are presented in BOLD type. Several pesticides listed in IRIS have been ...