1

Regulatory Flexibility Act Section 610 Review of the

Arsenic National Primary Drinking Water Regulations

United States Environmental Protection Agency

Office of Water

November 9, 2011
2

Results of Section 610 Review of the Arsenic Drinking Water Regulation

Background

On January 22, 2001 (66 FR 6976) EPA promulgated a new National Primary Drinking Water 

Regulation (NPDWR) for arsenic as authorized by the Safe Drinking Water Act (SDWA). In 

this action, EPA changed the arsenic maximum contaminant level (MCL) from 50 μg/L to 10 

μg/L, set the arsenic maximum contaminant level goal (MCLG) at zero, and required arsenic

monitoring for new systems. The Arsenic Rule was to become effective 60 days after 

publication, on March 23, 2001. However, the effective date was delayed while the Agency

sought independent reviews of the scientific and cost issues associated with the rule. After 

reassessment of the Arsenic Rule, it became effective on February 22, 2002.

Before the Arsenic Rule was promulgated EPA developed a Regulatory Flexibility Analysis. 

EPA also took several steps to lessen the impacts on small entities. These steps included: (1) 

Providing small systems additional time to comply through a provision for exemptions that 

would provide systems serving fewer than 3,300 persons up to an additional nine years to 

comply, and (2) developing a small entity compliance guide to help small systems comply with 

this rule. 

Section 610 of the Regulatory Flexibility Act requires federal agencies to review regulations that 

have significant economic impact on a substantial number of small entities within 10 years of 

their adoption as final rules. This review was announced in the Regulatory Agenda which was 

published in the Federal Register on December 20, 2010 (75 FR 79856). As part of this review, 

EPA considered, and solicited comments on, the following factors: (1) The continued need for 

the rule; (2) the nature of complaints or comments received concerning the rule; (3) the 

complexity of the rule; (4) the extent to which the rule overlaps, duplicates, or conflicts with 

other Federal, State, or local government rules; and (5) the degree to which technology, 

economic conditions, or other factors have changed in the area affected by the rule. 

EPA received eight comment letters in response to the December 20, 2010 Federal Register 

notice. All the letters are available for public inspection in the rulemaking docket (docket 

number EPA-HQ-OW-2010-0728 at www.regulations.gov). Pursuant to section 610 of the 

Regulatory Flexibility Act, EPA has reviewed this rule to determine if it should be continued 

without change, or should be rescinded or amended to minimize adverse economic impacts on 

small entities. The results of EPA’s Section 610 review of the Arsenic Rule are presented in this 

report.

Discussion of Factors required by Section 610 of the Regulatory Flexibility Act 

1. Continued need for the rule.

Most commenters explicitly stated the continued need for the Arsenic Rule because arsenic 

continues to be a public health concern for public water systems across the country with high 

arsenic levels. None of the commenters suggested the rule should be rescinded.
3

Two commenters suggested that the continued need for the rule should be evaluated through 

EPA’s six year review process. EPA is required to review its existing NPDWRs at least every

six years and to revise as appropriate. The six year review is a thorough review of current health 

effects assessments, changes in technology, and other factors that could support a regulatory

revision that will maintain or improve public health protection. EPA will continue to review the 

Arsenic Rule every six years, as required by the SDWA, and revise the rule if appropriate. The 

next six year drinking water rule review is due in 2016. 

Two commenters challenged the revision of the arsenic MCL from 50 μg/L to 10 μg/L but did 

not contend that there was no continued need for the rule. Those commenters expressed the 

opinion that the MCL revision was made with little scientific evidence of health risk and 

benefits. In deriving the 2001 MCL, EPA followed the recommendations from the National 

Academy of Sciences Report, Arsenic in Drinking Water (National Research Council, NRC, 

1999). NRC (1999) reviewed all the available human data on cancer and non-cancer effects 

from exposure to arsenic in drinking water along with experimental evidence on metabolism and 

mode of action. In addition, EPA requested reviews by 1) the National Academy of Sciences 

(NAS) on the Agency's interpretation and application of arsenic research, 2) the National 

Drinking Water Advisory Council (NDWAC) on the assumptions and methodologies underlying 

the Agency's estimate of arsenic compliance costs, and 3) its Science Advisory Board (SAB) on 

the benefits associated with the Rule. The EPA Administrator announced on October 31, 2001, 

that the 10 ppb standard for arsenic would remain stating that, "the 10 ppb protects public health 

based on the best available science and ensures that the cost of the standard is achievable."

2. Nature of complaints or comments received concerning the rule.

There were five main issues for which the commenters requested that the rule be amended to 

ease burden on small systems. These issues were the cost associated with treatment, the disposal 

of treatment waste streams, the calculation for compliance with the MCL, the difficulties 

associated with using alternative treatment technologies, and the difficulty in communicating the 

health risks of arsenic exposure to the public. We address each of these concerns and the actions 

that EPA has taken to resolve these concerns below:

 Cost Associated with Treatment

Nearly all commenters cited the cost of adding arsenic treatment as a significant burden for water 

systems. 

EPA is aware that it is more difficult for small systems to spread the cost of adding treatment 

among their smaller customer base than it is for larger systems. Systems needing to install 

treatment may apply for financial assistance through EPA's Drinking Water State Revolving 

Fund (DWSRF). Between 1997 and 2010, states have used DWSRF funds to provide $7.6 

billion in low-interest loans to small public water systems and have entered into over 5,900 

assistance agreements to fund projects to small systems to improve infrastructure. The program 

also maintains its commitment to providing funding to systems with the greatest demonstrated 

need. Thirty-eight percent of all DWSRF assistance funded in 2009 went to systems serving 
4

10,000 or fewer people. EPA has been working with the states to better target DWSRF set-asides 

to small systems likely to be challenged by particular rules.

In addition EPA’s Drinking Water program has partnered with U.S. Department of Agriculture’s 

Rural Utilities Service (USDA-RUS) to offer a wide array of assistance options to address the 

SDWA compliance needs of small systems. More information about this partnership can be 

found at: http://water.epa.gov/type/drink/pws/smallsystems/partners.cfm. 

To help systems determine the best solution for complying with the Arsenic Rule the EPA Office 

of Research and Development (ORD) has invested more than $20 million in arsenic removal 

demonstration projects and installed 49 treatment systems in 26 states. ORD’s research is 

focused on the development and evaluation of innovative methods and cost-effective 

technologies for arsenic treatment. Systems are not required to use any specific technology. 

Systems can use technologies not listed as best available technologies (BATs) if they are 

effective at removing arsenic from drinking water.

EPA has also posted a significant amount of arsenic compliance assistance materials on the EPA 

website http://www.epa.gov/safewater/arsenic/compliance.html. EPA’s arsenic technology

experts have provided many training sessions, hosted conferences, and provided direct assistance 

to systems. EPA also works with states and Federally-funded technical assistance providers to 

get information out to states and small water systems.

 Disposal of Waste Stream

Three commenters communicated the frustrations of impacted public water systems where onsite disposal of backwash water from arsenic treatment is prohibited.

EPA is aware of the difficulties of disposing of treatment waste streams and that hazardous waste 

regulations vary from state to state. To address liquid waste streams, EPA has demonstrated 

through arsenic demonstration projects that treatment processes can be designed and operated to 

eliminate the need to dispose of wastewater flows. Backwash waters can be reincorporated into 

the beginning of the treatment process, rather than disposing of it. Solid wastes, from an iron 

filtration process or spent media from an adsorptive process, have been shown to pass EPA’s 

Toxicity Characteristic Leaching Procedure (TCLP), which typically would allow them to be 

disposed into a non-hazardous sanitary landfill. Water systems should review state hazardous 

waste regulations for liquids and solids so waste considerations can be addressed during the 

initial design or modification of a treatment facility. 

 Compliance Determination for the MCL

EPA received several comments on how compliance is determined for the Arsenic MCL. Those 

commenters were concerned that because compliance determination is based on a running annual 

average of quarterly samples, public water systems with newly installed treatment may still be in 

violation of the MCL even if their most recent result is below the MCL. 

EPA drinking water rules, not only the Arsenic Rule, have been written to ensure contaminant 

levels are reliably and consistently below the regulated level before returning a system to 
5

compliance with a rule. The state cannot make a determination that the system is reliably and 

consistently below the MCL until a minimum of two consecutive ground water, or four 

consecutive surface water samples, have been collected (§141.23(c)(8)). Thus, systems 

installing treatment (or making other adjustments to comply over the long term) are out of 

compliance; but the concern raised by commenters is a onetime occurrence. A system can

include a statement in the public notice and Consumer Confidence Report (CCR) indicating the 

system has addressed the issue (via treatment, blending, etc.) and is currently sampling to ensure 

the process is working correctly and does not exceed the MCL. 

 Difficulty Using Alternative Treatment Technologies

EPA received two comments on the difficulty of using point-of-use (POU) devices as an 

alternative treatment technology due to the resource intensive oversight required for these types 

of devices. 

Before the Arsenic Rule was promulgated EPA identified affordable small system compliance 

technologies. Among these small system compliance technologies is a point-of-use (POU) 

device option operated and maintained by the public water system, allowed by the 1996 SDWA 

Amendments in SDWA Section 1412(b)(4)(E)(ii). At least one western state developed its own 

guidance for how a POU program would be administered by water systems in the state. 

EPA recognizes that complying with the requirements for point-of-use treatment technologies 

can be challenging. EPA developed guidance to promote Point-of-Use devices (Point-of-Use or 

Point-of Entry Treatment Options for Small Drinking Water Systems EPA 815-R-06-010). EPA 

has also developed a tool to assess the capital and operational & maintenance cost for POUs 

(Cost Evaluation of Point-of-Use and Point-of-Entry Treatment Units for Small Systems: Cost 

Estimating Tool and User Guide. EPA 815-B-07-001).

 Risk Communication

EPA received a comment that the consumer confidence report (CCR) public health information 

required when arsenic levels are below the MCL of 10 ppb but above 5 ppb is confusing and 

difficult for the general public to understand. 

While EPA provides arsenic education language in the Revised State Implementation Guidance 

for Consumer Confidence Report (CCR) Rule (EPA 816-R-09-010), EPA allows water systems 

the flexibility to tailor their information to specific local situations. Systems that want to use 

language significantly different than that provided by EPA must develop comparable language in 

consultation with the state. 

3. Complexity of the rule.

Overall, commenters did not find the Arsenic Rule overly complex. Comments regarding the 

complexity of the rule were focused on the determination of compliance with the rule. After 

considering the comments EPA believes that there are adequate guidance documents available on 

the EPA website to help systems and states understand the correct implementation of the rule. In 

addition to providing guidance documents, EPA also conducts periodic training courses to help 
6

the regulated community understand the requirements of the Arsenic Rule. More information on 

past training courses can be found at: http://www.epa.gov/safewater/arsenic/compliance.html.

4. Extent to which the rule overlaps, duplicates, or conflicts with other federal, state, or 

local government rules.

Some commenters expressed concerns about the burden that results from complying with the 

rule as it relates to the appropriate disposal of wastes generated after the treatment of water 

sources with elevated levels of arsenic. The main concern is that some systems might have to 

comply with other environmental statues as a result of the generation of wastes from the 

treatment of water to remove arsenic. EPA has developed guidance documents to help the 

regulated community comply with the rule while reducing the amount of waste generated. Given 

the targeted nature of the rule towards drinking water, and the guidance provided for complying 

with other rules, EPA does not believe that the Arsenic Rule overlaps, duplicates or conflicts 

with other rules. 

Two commenters noted that since Arsenic is an organic chemical, the rule can be interpreted as 

overlapping with the Phase II/V Rules. The Phase II/V Rules were promulgated by the EPA in 

1991 and 1992 and did not include arsenic, while the original Arsenic Rule was promulgated by 

EPA in 1975. EPA does not believe that the Arsenic Rule overlaps, duplicates or conflicts with 

the Phase II/V Rules. 

5. The degree to which technology, economic conditions, or other factors have changed in 

the area affected by the rule.

Commenters noted that there are new treatment technologies for arsenic and that EPA’s arsenic 

removal demonstration studies provided valuable information regarding technologies that are 

effective in removing arsenic. However, the economic condition of many small communities has 

worsened in recent years. Most commenters expressed concern over the increasing difficulty for 

many systems to devote sufficient resources to ensure compliance. The concern over the cost of 

adding arsenic treatment was addressed under section (2): Nature of complaints of comments 

received concerning the rule.

Many commenters also expressed concern that EPA will further lower the MCL for arsenic. 

This concern may stem from the draft IRIS Toxicological Review for Inorganic Arsenic which 

provides new estimated cancer risks from arsenic exposure that are five to ten fold greater than 

EPA’s estimates when the MCL was promulgated in 2001. 

The new risk assessment is still ongoing. The draft IRIS inorganic arsenic risk assessment was

released to the Science Advisory Board (SAB) and simultaneously to the public for review and 

comment in February 2010. EPA received the final SAB report on March 1, 2011. The SAB 

approved of EPA’s scientific basis to estimate cancer risk and made a number of 

recommendations to improve clarity and transparency of the 2010 draft assessment. EPA will 

consider SAB’s recommendations to refine the IRIS inorganic arsenic risk assessment before the 

final assessment will be posted to the IRIS database. Up-to-date information regarding the 

arsenic risk assessment can be found at: 
7

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=219111

While the final revised arsenic risk assessment will provide critical information for EPA’s 

review of the existing MCL, it is only one of the key elements considered by the Agency in 

determining if it is appropriate to revise the standard. In reviewing NPDWRs, EPA evaluates five 

key elements as appropriate: analytical and treatment feasibility, implementation related issues, 

occurrence and exposure, economic impact and health effects. 

EPA will continue to periodically review the effectiveness of the Arsenic Rule through the 

framework provided by the SDWA. SDWA requires that EPA review all of its drinking water 

regulations every six years and revise them if appropriate. The purpose of the review is to 

identify current health effects assessments, changes in technology, and other factors that could 

support a regulatory revision that will maintain or strengthen public health protection. 

EPA completed its first Six Year Review in 2003 and its second Six Year Review in 2010. The 

conclusion of the second Six Year Review was that the Agency did not believe a revision to the 

NPDWR for arsenic was appropriate because the reassessment of the health risks resulting from 

exposure to arsenic is ongoing. Once the final inorganic arsenic risk assessment is issued, EPA 

will have to decide if the Agency will undertake a review to the arsenic standard at that time or if 

the Agency wants to defer to the next drinking water rule review due in 2016. 

Conclusion

After reviewing all the comments regarding this Regulatory Flexibility Act Section 610 review, 

the Agency has concluded that revisions or amendments to minimize economic impacts on small 

entities from the Arsenic Rule are not warranted at this time. EPA has taken a number of actions 

related to the Arsenic Rule and its implementation including:

 Providing small systems additional time to comply through a provision for exemptions.

 Requesting reviews by NAS, NDWAC and SAB in 2001.

 Conducting 49 arsenic treatment demonstration projects in 26 states.

 Providing $7.6 billion in DWSRF low-interest loans between 1997 and 2010 small public 

water system assistance.

 Working with USDA-RUS to assist small systems in achieving compliance with the 

Arsenic Rule.

 Providing training, guidance and other materials to support implementation of the 

Arsenic Rule. 

EPA will continue to evaluate the effectiveness of the Arsenic Rule and the potential to decrease 

the rule’s implementation burden within the Six Year Review framework provided by the 

SDWA and through other Agency initiatives.