Stage 2 Dbp Rule

30/11/2022por Mentores

In the MOU, the Advisory Committee recommended maintaining the MCLs for TTHM and HAA5 at 0.080 mg/L and 0.060 mg/L respectively, but modifying the two-phase compliance calculation to facilitate the transition of systems from the current annual average (AAR) to a current average calculation (LRAA). In the first phase, systems would continue to meet DBPR Level 1 MCLs as RBAs and simultaneously MCLs of 0.120 mg/L for TTHM and 0.100 mg/L for AAA5, calculated as LRAAs. RBA calculations average all samples taken from a distribution system over a one-year period, but LRAA calculations average all samples taken at each individual sampling location in a distribution system over a one-year period. The systems would also conduct an initial distribution system assessment (IDSE) to select compliance monitoring sites that reflect the higher TTHM and HAA5 scores in the distribution system. The second phase of compliance would require MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for AAA5, calculated as LRAAs at the individual monitoring sites identified by the ESDI. The first phase has been deleted in the final rule, as indicated in section IV.C. The Environmental Protection Agency (EPA) today announced the final rule, the Stage 2 Disinfectant and Disinfection By-Product Rule (DBPR), to provide increased protection against potential cancer risks and the impact of disinfection by-products (DBPs) on reproductive and developmental health. The Final Phase 2 DBPR contains maximum pollutant targets for chloroform, monochloroacetic acid and trichloroacetic acid; national rules for primary drinking water, including maximum levels of pollutants (MCLs) and monitoring, reporting and reporting obligations for whole trihalomethanes (TTHM) and haloacetic acids (AAA5); and the revision of reduced bromate monitoring requirements. This document also specifies the best available technologies for final LCMs. The EPA also approves additional analytical methods for the determination of disinfectants and DBPs in drinking water. The EPA estimates that DBPR Level 2 will reduce the potential cancer risks and effects associated with BPD on reproductive and developmental health by reducing peak and medium levels of DBP in the drinking water supply. c. Summary of key observations.

The EPA received few comments on the MCAA and TCAA. Most of the comments on the MCCM for TCAA and MCAA were general MCLG issues, including the derivation of the CBC. Some commentators have asked why MCAA, TCAA and chloroform were calculated with a CSR of 20%. In particular, some commenters have compared these calculations to those of the DBCM in DBPR Level 1, which uses 80%. Each of the MCLGs established for chloroform, TCAA and MCAA under this rule is calculated on the basis of the best available scientific data and the current approach of the EPO Water Board to calculate the CSR. The EPA chose a CSR of 20% rather than 80% because of clear evidence of exposure from other sources. Data restrictions prevent the derivation of a particular CSR. The following documents have been developed to support the development of final rules. The EPO has included requirements specific to successive systems, as states have taken very different approaches to regulating SPDs in successive systems in previous rules. For example, some states have not regulated DBP levels in successive systems that provide disinfected water but do not add disinfectant.

Other States have established compliance with DBP standards on the basis of the combined distribution system, which includes both the wholesaler and successive systems. In this case, the sites of successive systems are treated as monitoring sites within the combined distribution network. None of these approaches provide the same level of health protection that non-consecutive systems receive under Level 1 GNH. Once fully transposed, the current regime will provide similar protection for consumers in successive regimes. This section first summarizes existing regulations to control concentrations of DBPs in drinking water. The Level 2 GDN establishes regulatory requirements that go beyond these rules and target high-risk systems and provide more equitable protection against DBPs throughout the distribution system. This section then summarizes the broad involvement of stakeholders in the development of the Level 2 HPPR. This rule also contains minor corrections to drinking water regulations, particularly public notice tables.

In recent regulations, new endnotes have been added to these tables; However, the corresponding numbering of footnotes in the tables has not been changed. In addition, this rule makes a minor correction to the Level 1 rule for disinfectants and disinfectant by-products by replacing a phrase that was accidentally removed. c. Conclusions. The EPA`s weight-of-evidence assessment of the best available science on carcinogenicity, reproductive and developmental effects, coupled with widespread exposure to DBPs, supports incremental regulatory changes to the current rule to reduce DBPs and ensure equitable protection of public health. Other commentators expressed concern that the proposed definition of the consecutive system was inconsistent with the use of the term prior to rule-making. The EPA acknowledges that the agency has not formally defined the term before, but believes that the definition of the current rule best addresses the concerns of all commentators, while ensuring accountability and protection of public health in the simplest way possible given the many successive systemic scenarios that currently exist. Commentators generally supported the proposed definitions. However, commentators expressed some concerns, particularly with respect to the inclusion of a period for water supply, which defined whether a system was a sequential system (proposed to trigger plant-based monitoring requirements) or a wholesale system (proposed to determine whether there is a combined distribution system).

EPA removed this requirement from the final rule; The population-based monitoring requirements in the final rule do not have to define how long a facility must operate to be considered an asset, and the EPA has given states some flexibility in determining which systems include a combined distribution system (without providing a time criterion). In support of this rule, the EPA has developed health criteria documents that summarize available toxicological data on brominated THMs (EPA, 2005b), brominated AAH (EPA, 2005c), MX (EPA 2000b), MCAA (EPA, 2005d) and TCAA (EPA, 2005e). The 2003 DCAA IRIS assessment (EPA 2003b) and an addendum (EPA 2005k) also include an analysis published after Level 1. It summarizes drinking water exposure information and establishes a slope factor for DCAA. IRIS also has toxicological assessments for chloroform (EPA 2001a), chlorine dioxide and chlorite (USEPA 2000c) and bromate (USEPA 2001b) and is currently re-evaluating TCAA. Following a thorough analysis of available data and regulatory options considered by the Advisory Committee and a review of public comments on the proposed DBPR Level 2 (USEPA 2003a), CEPOL is finalizing a control strategy for DBPR Level 2 consistent with key elements of the Memorandum of Understanding signed by participants in the PBD-M Level 2 Advisory Committee in September 2000. The EPA believes that exposure to chlorinated drinking water may be linked to cancer, reproductive and developmental risks. The EPA has determined that the risk targeting measures recommended in the MOU require only those systems with the greatest risk of treatment and operational changes, while providing protection against potential health problems related to DBPs and microbial contaminants.

CEPOL carefully evaluated and expanded the Advisory Committee`s recommendations and public comments to develop today`s rule. EPA has also made simplifications to minimize complications for public water systems as they transition to DBPR Level 2 compliance while expanding public health protection. The DBPR Level 2 requirements are described in detail in Section IV of this Preamble. The calculation of the IDSE and LRAA will result in an overall decrease in DBP concentrations and reduce short-term exposure to elevated DBP concentrations in some areas, but this improved approach to DBP regulation will still allow for individual samples of DBP above the MCL, even if Level 2 systems are DBPR compliant.