SUMMARY: The Safe Drinking Water Act (SDWA) requires the United States Environmental Protection Agency (EPA) to conduct a periodic review of existing National Primary Drinking Water Regulations (NPDWRs) and determine which, if any, need to be revised. The purpose of the review, called the Six-Year Review, is to identify those NPDWRs for which current health effects assessments, changes in technology, and/or other factors provide a health or technical basis to support a regulatory revision that will improve or strengthen public health protection…
DATES: Comments must be received on or before May 28, 2010, 60 days after publication in the Federal Register.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OW-2008-0747, by one of the following methods:
http://www.regulations.gov : Follow the online instructions for submitting comments.
Mail: Water Docket, Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania Ave., NW., Washington, DC 20460.
Hand Delivery: EPA Docket Center Public Reading Room, EPA Headquarters West, Room 3334, 1301 Constitution Ave., NW., Washington, DC.
Instructions: Direct your comments to Docket ID No. EPA-HQ-OW-2008-0747.
… a. Issues Identified by the EPA/State Workgroup
To gather input regarding implementation-related concerns and help the Agency identify the top one or two issues for Six-Year Review 2 (USEPA, 2009h), EPA requested that the Association of State Drinking Water Administrators (ASDWA) form a workgroup of member States and primacy agencies. In the fall of 2007, ten member States agreed to participate and confer with EPA on a joint EPA/State workgroup. The State/EPA workgroup initially identified 22 issues, but narrowed the list to 4 items. Of these four items, three appeared to be within the scope of this NPDWR review, and EPA agreed that an information or fact sheet might be appropriate for the fourth item regarding public notification (PN) requirements for fluoride.10 The EPA/State workgroup agreed that public input via the Federal Register would provide additional insight on the national scope of these three issues (i.e., Are the issues isolated to a few States or more widespread?), the importance of these issues to other States as well as water systems, and ideas on potential resolutions. Table V-5 provides a brief description of the remaining three issues and some of the potential solutions discussed in the workgroup meetings.
10 Currently, PWSs that exceed the fluoride MCL of 4.0 mg/L are required to notify their customers within 30 days of the exceedance. If a PWS exceeds the fluoride SMCL of 2.0 mg/L, they are required to notify their customers within 12 months of the exceedance. The States voiced concerns about (1) the confusion that occurs between the different PN requirements for the MCL and the SMCL, and (2) the timeliness of the PN requirement for the SMCL. The workgroup indicated that waiting 12 months to notify customers of an exceedance of the SMCL does not adequately protect young children from dental fluorosis during a critical stage of tooth enamel development. The participating States requested that EPA consider regulatory revisions to clarify the PN requirements and better reflect the health and aesthetic implications of each. EPA noted that PN requirements are not within the scope of this NPDWR review. However the Agency agreed that a fact or information sheet may be useful to clarify any confusion.
a. Background. EPA published the current NPDWR for fluoride on April 2, 1986 (51 FR 11396 (USEPA, 1986c)). The NPDWR established an MCLG and an MCL of 4.0 mg/L. The MCLG was developed from a lowest effect level for crippling skeletal fluorosis of 20 mg/day with continuous exposures over a 20-year or longer period. The lowest-observed-adverse-effect level (LOAEL) was divided by an uncertainty factor of 2.5 and a drinking water intake of 2 liters/day (L/day) to obtain the MCLG. Drinking water was considered to be the only source of exposure for the calculation. At the same time, EPA published a secondary maximum contaminant level (SMCL) for fluoride of 2.0 mg/L to protect against dental fluorosis, which was considered to be an adverse cosmetic effect. PWSs exceeding the fluoride SMCL must provide public notification to their customers.
Fluoride is unique because of its beneficial effects at low level exposures, and because it is voluntarily added to some drinking water systems as a public health measure for reducing the incidence of cavities among the treated population. The amount of fluoride added to drinking water for fluoridation ranges from 0.7 to 1.2 mg/L, depending on ambient air temperatures. The decision to fluoridate a water supply is made by the State or local municipality, and is not mandated by EPA or any other Federal entity.
b. Technical Reviews. As a result of the first Six-Year Review of the fluoride NPDWR (67 FR 19030 (USEPA, 2002c) (preliminary); 68 FR 42908 (USEPA, 2003e) (final)), EPA requested that the National Research Council (NRC) of the National Academies of Science (NAS) conduct a review of the recent health and exposure data on orally ingested fluoride. In 2006, the NRC published the results of their evaluation in a report entitled, Fluoride in Drinking Water: A Scientific Review of EPA’s Standards. Based on its review, NRC concluded that severe dental fluorosis is an adverse health effect when it causes confluent thinning and pitting of the enamel, a situation that compromises the function of the enamel in protecting the dentin and eventually the pulp from decay and infection. There was consensus among the committee that severe dental fluorosis is an effect that should be avoided and that “exposure at the MCLG clearly puts children at risk of developing severe enamel fluorosis.” In addition, the committee examined the scientific data on the impact of fluoride on the strength and structure of bone and the majority concluded that the MCLG “is not likely to be protective against bone fractures.” NRC recommended that EPA use the available dose-response data for the effects of fluoride on severe dental fluorosis and skeletal fractures in combination with data on the relative contribution of drinking water to total fluoride exposure to identify an MCLG that would be protective against these effects.
The NRC also evaluated the impact of fluoride on reproduction and development, neurotoxicity and behavior, the endocrine system, genotoxicity, cancer and other effects. They concluded that the available data were inadequate to determine if a risk for effects on these endpoints exists at an MCLG of 4 mg/L and made recommendations for additional research. After considering the genotoxicity data, cancer studies in humans and animals, and studies of mode of action in cell systems, NRC determined that the evidence on the potential of fluoride to initiate or promote cancers, particularly of the bone, is tentative and mixed. They recommended that EPA await the results and publication of an in-process hospital-based, case-control study of osteosarcoma and fluoride exposure from the Harvard School of Dental Medicine before determining if an Agency update of the cancer risk assessment for fluoride is necessary.19
19 At this time, the results of the osteosarcoma cancer study recommended by NAS have not been published.
c. Review Result. The Agency does not believe a revision to the NPDWR for fluoride is appropriate at this time because the Agency’s Office of Water (OW) is in the process of developing its dose-response assessment of the noncancer impacts of fluoride on severe dental fluorosis and the skeletal system. In addition, the OW is updating its evaluation of the relative contribution of drinking water to total fluoride exposure considering the contributions from dental products, foods, pesticide residues, and other sources such as ambient air and medications. Once the Agency completes and publishes peer reviewed versions of these in-process assessments, it will be able to determine the potential impacts on the MCLG, MCL, and/or the SMCL and whether any revisions to these would be appropriate…