7762 Federal Register / Vol. 76, No. 29 / Friday, February 11, 2011 / Proposed Rules 

(2) A quorum consists of five 

members. 

* * * * * 

Dated: February 2, 2011. 

Thomas L. Strickland, 

Assistant Secretary for Fish and Wildlife and 

Parks, Department of the Interior. 

Dated: January 18, 2011. 

Beth G. Pendleton, 

Regional Forester, USDA—Forest Service. 

[FR Doc. 2011–2959 Filed 2–10–11; 8:45 am] 

BILLING CODE 3410–11–P; 4310–55–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 141 

[EPA–HQ–OW–2008–0692, EPA–HQ–OW– 

2009–0297; FRL–9262–8] 

RIN 2040–AF08 

Drinking Water: Regulatory 

Determination on Perchlorate 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Regulatory determination. 

SUMMARY: This action presents EPA’s (or 

the Agency’s) regulatory determination 

for perchlorate in accordance with the 

Safe Drinking Water Act (SDWA). 

Specifically, EPA has determined that 

perchlorate meets SDWA’s criteria for 

regulating a contaminant—that is, 

perchlorate may have an adverse effect 

on the health of persons; perchlorate is 

known to occur or there is a substantial 

likelihood that perchlorate will occur in 

public water systems with a frequency 

and at levels of public health concern; 

and in the sole judgment of the 

Administrator, regulation of perchlorate 

in drinking water systems presents a 

meaningful opportunity for health risk 

reduction for persons served by public 

water systems. Therefore, EPA will 

initiate the process of proposing a 

national primary drinking water 

regulation (NPDWR) for perchlorate. 

DATES: For purposes of judicial review, 

the regulatory determination is issued as 

of February 11, 2011, as provided in 40 

CFR 23.7. 

ADDRESSES: EPA has established dockets 

for this action under Docket ID numbers 

EPA–HQ–OW–2008–0692 and EPA– 

HQ–OW–2009–0297. All documents in 

these dockets are listed on the http:// 

www.regulations.gov Web site. Although 

listed in the index, some information is 

not publicly available, e.g., Confidential 

Business Information or other 

information whose disclosure is 

restricted by statute. Certain other 

material, such as copyrighted material, 

is not placed on the Internet, but will be 

publicly available in hard copy form. 

Publicly available docket materials are 

available either electronically through 

http://www.regulations.gov or in hard 

copy at the Water Docket, EPA/DC, EPA 

West, Room 3334, 1301 Constitution 

Ave., NW., Washington, DC. The Public 

Reading Room is open from 8:30 a.m. to 

4:30 p.m., Monday through Friday, 

excluding legal holidays. The telephone 

number for the Public Reading Room is 

(202) 566–1744, and the telephone 

number for the EPA Docket Center is 

(202) 566–2426. 

FOR FURTHER INFORMATION CONTACT: Eric 

Burneson, Office of Ground Water and 

Drinking Water, Standards and Risk 

Management Division, at (202) 564– 

5250 or e-mail burneson.eric@epa.gov. 

For general information contact the EPA 

Safe Drinking Water Hotline at (800) 

426–4791 or e-mail: hotlinesdwa@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Table of Contents 

I. General Information 

Does this action impose any requirements 

on my public water system? 

II. Background 

A. What is the purpose of this action? 

B. Background on Perchlorate Regulatory 

Determinations 

C. What is EPA’s final regulatory 

determination on perchlorate and what 

happens next? 

III. Final Regulatory Determination for 

Perchlorate 

A. May perchlorate have an adverse effect 

on the health of persons? 

B. Is perchlorate known to occur or is there 

a substantial likelihood that perchlorate 

will occur in public water systems with 

a frequency and at levels of public health 

concern? 

C. Is there a meaningful opportunity for the 

reduction of health risks from 

perchlorate for persons served by public 

water systems? 

D. Regulatory Determination 

E. Key Commenter Issues 

1. Health Implications of Perchlorate 

Exposure above the RfD 

2. Other Thyroid Inhibiting Chemicals 

3. Perchlorate in Food 

4. Iodide Nutritional Status 

5. Physiologically-Based Pharmacokinetic 

(PBPK) Modeling 

F. Next Steps 

IV. References 

Abbreviations and Acronyms 

CBI—confidential business information 

CCL—Contaminant Candidate List 

EPA—U.S. Environmental Protection Agency 

FR—Federal Register 

HRL—health reference level 

kg—kilogram 

L—liter 

MCL—maximum contaminant level 

MRL—Minimum Reporting Limit 

NOEL—no observed effect level 

NPDWR—National Primary Drinking Water 

Regulation 

NRC—National Research Council 

PBPK—Physiologically-Based 

Pharmacokinetic 

PWS—public water system 

RfD—reference dose 

SDWA—Safe Drinking Water Act 

UCMR—Unregulated Contaminant 

Monitoring Rule 

μg—microgram (one-millionth of a gram) 

U.S.—United States 

I. General Information 

Does this action impose any 

requirements on my public water 

system? 

Today’s action notifies interested 

parties of EPA’s determination to 

regulate perchlorate, but imposes no 

requirements on public water systems 

(PWSs). However, this action also 

initiates the process to develop a 

national primary drinking water 

regulation (NPDWR) for perchlorate. At 

such time as the Agency establishes an 

NPDWR, certain PWSs will be required 

to take action to comply with the 

regulation in accordance with the 

schedule specified in the regulation. 

II. Background 

A. What is the purpose of this action? 

The purpose of today’s action is to 

present EPA’s final determination to 

regulate perchlorate in drinking water, 

the rationale EPA used to make this 

regulatory determination, and EPA’s 

response to certain key issues raised by 

commenters on previous Federal 

Register (FR) notices on the drinking 

water regulatory determination for 

perchlorate. (All comments are 

addressed in a Response to Comments 

document that is available in EPA’s 

docket ID No. EPA–HQ–OW–2009–0297 

for this regulatory determination.) 

B. Background on Perchlorate 

Regulatory Determinations 

The statutory and regulatory 

background for this action is described 

in detail in the October 10, 2008, FR 

notice discussing EPA’s preliminary 

regulatory determination for perchlorate 

(73 FR 60262; USEPA 2008a). Briefly, 

SDWA section 1412(b)(1)(A), as 

amended in 1996, requires EPA to make 

a determination whether to regulate at 

least five contaminants from its 

Contaminant Candidate List (CCL) every 

five years. To regulate a contaminant in 

drinking water, EPA must determine 

that it meets three criteria: (1) The 

contaminant may have an adverse effect 

on the health of persons; (2) the 

contaminant is known to occur or there 

is a substantial likelihood that the 

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contaminant will occur in public water 

systems with a frequency and at levels 

of public health concern; and (3) in the 

sole judgment of the Administrator, 

regulation of such contaminant presents 

a meaningful opportunity for health risk 

reduction for persons served by public 

water systems. Once EPA makes a 

determination to regulate a contaminant 

in drinking water, SDWA requires that 

EPA issue a proposed NPDWR within 

24 months and a final NPDWR within 

18 months of proposal. 

EPA included perchlorate on the first, 

second, and third CCLs that were 

published in the Federal Register on 

March 2, 1998 (63 FR 10273; USEPA 

1998), February 24, 2005 (70 FR 9071; 

USEPA 2005a), and October 8, 2009 (74 

FR 51850; USEPA 2009a), respectively. 

On May 1, 2007, EPA published an 

update on the Agency’s evaluation of 

perchlorate as part of the preliminary 

regulatory determination for 11 other 

CCL 2 contaminants (72 FR 24016; 

USEPA 2007). The Agency did not make 

a preliminary determination for 

perchlorate as part of this regulatory 

determination, but requested public 

comment on the options that the Agency 

was evaluating for perchlorate and 

requested information that could assist 

the Agency in its regulatory 

determination. EPA received eight 

comment letters in response to the May 

2007 document (72 FR 24016; USEPA 

2007) that addressed perchlorate. Public 

comments on the May 2007 document 

can be found online at http:// 

www.regulations.gov (Docket ID No. 

EPA–HQ–OW–2007–0068). 

On October 10, 2008, EPA published 

a preliminary regulatory determination 

for perchlorate (73 FR 60262; USEPA 

2008a), requesting public comment on 

its determination that perchlorate did 

not occur with a frequency and at levels 

of public health concern and regulation 

of perchlorate did not present a 

meaningful opportunity for health risk 

reduction for persons served by public 

water systems (the second and third 

criteria for regulating a contaminant 

under SDWA). The October 2008 notice 

describes in detail EPA’s basis for its 

preliminary determination not to 

develop an NPDWR for perchlorate (73 

FR 60262; USEPA 2008a). The Agency 

received nearly 33,000 comment letters 

on the October 2008 notice. Public 

comments on the October 2008 notice 

and supporting materials are available 

electronically at http:// 

www.regulations.gov (Docket ID No. 

EPA–HQ–OW–2008–0692). 

On August 19, 2009, EPA published 

the Perchlorate Supplemental Request 

for Comments (74 FR 41883; USEPA 

2009b) requesting comment on 

additional approaches to analyzing data 

related to EPA’s perchlorate regulatory 

determination. These additional 

comments were sought in an effort to 

ensure consideration of all potential 

options for evaluating whether there is 

a meaningful opportunity for human 

health risk reduction of perchlorate 

through a NPDWR. EPA stated that the 

alternative analyses presented in this 

notice could lead the Agency to make a 

determination to regulate perchlorate. 

EPA received over 6,000 comments on 

the August 2009 notice. 

EPA has evaluated the approximately 

39,000 public comments received on the 

May 2007 document, the October 2008 

notice, and August 2009 notice. EPA has 

prepared a response to comment 

document that addresses the comments 

related to the perchlorate regulatory 

determination (USEPA, 2010a). This 

response to public comment document, 

the public comments on the August 

2009 notice, and supporting materials 

are available electronically at http:// 

www.regulations.gov (Docket ID No. 

EPA–HQ–OW–2009–0297). 

C. What is EPA’s final regulatory 

determination on perchlorate and what 

happens next? 

After careful review and 

consideration of public comments on 

the May 2007, October 2008, and 

August 2009 notices, the Agency has 

made a determination to regulate 

perchlorate in drinking water. EPA has 

found that perchlorate may have an 

adverse effect on human health. EPA 

has reversed its October 2008 

preliminary determination not to 

develop an NPDWR for perchlorate and 

now concludes, based on the analysis 

presented in this regulatory 

determination, that there is a substantial 

likelihood that perchlorate will occur in 

public water systems with a frequency 

and at levels of public health concern. 

Finally, EPA has determined that 

regulation of perchlorate presents a 

meaningful opportunity to reduce 

health risk for persons served by public 

water systems. 

EPA is initiating the development of 

a proposed NPDWR for perchlorate. 

EPA intends to publish a proposed 

regulation and analyses required by 

SDWA for public review and comment 

within 24 months of this regulatory 

determination. EPA will consider the 

public comments and expects to 

promulgate a final regulation within 

18 months of the proposal. 

III. Final Regulatory Determination for 

Perchlorate 

In making final regulatory 

determinations, EPA uses the criteria 

mandated by the 1996 SDWA 

Amendments. Specifically, EPA has 

found that perchlorate may have an 

adverse effect on the health of persons, 

that perchlorate occurs or there is a 

substantial likelihood that perchlorate 

will occur in public water systems with 

a frequency and at levels of public 

health concern, and that regulation of 

perchlorate in drinking water systems 

presents a meaningful opportunity for 

health risk reduction for persons served 

by public water systems. 

A. May perchlorate have an adverse 

effect on the health of persons? 

Yes. The perchlorate anion is 

biologically significant specifically with 

respect to the functioning of the thyroid 

gland. Perchlorate can interfere with the 

normal functioning of the thyroid gland 

by inhibiting the transport of iodide into 

the thyroid, resulting in a deficiency of 

iodide in the thyroid. Perchlorate 

inhibits (or blocks) iodide transport into 

the thyroid by chemically competing 

with iodide, which has a similar shape 

and electric charge. The transfer of 

iodide from the blood into the thyroid 

is an essential step in the synthesis of 

thyroid hormones. The thyroid 

hormones play an important role in the 

regulation of metabolic processes 

throughout the body and are also critical 

to developing fetuses and infants, 

especially with respect to brain 

development. Because the developing 

fetus depends on an adequate supply of 

maternal thyroid hormone for its central 

nervous system development during the 

first and second trimester of pregnancy, 

iodide uptake inhibition from low-level 

perchlorate exposure has been 

identified as a concern in connection 

with increasing risk of 

neurodevelopmental impairment in 

fetuses of hypothyroid mothers. Poor 

iodide uptake and subsequent 

impairment of the thyroid function in 

pregnant and lactating women have 

been linked to delayed development 

and decreased learning capability in 

their infants and children (NRC, 2005). 

Additionally, deficiency during 

childhood reduces child growth and 

cognitive motor function (Zimmerman, 

2009). Therefore, EPA finds that 

perchlorate may have an adverse effect 

on the health of persons. 

B. Is perchlorate known to occur or is 

there a substantial likelihood that 

perchlorate will occur in public water 

systems with a frequency and at levels 

of public health concern? 

Yes. EPA has determined that 

perchlorate occurs or there is a 

substantial likelihood that perchlorate 

will occur with a frequency and at 

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7764 Federal Register / Vol. 76, No. 29 / Friday, February 11, 2011 / Proposed Rules 

1No observed effect level (NOEL)—an exposure 

level at which there are no statistically or 

biologically significant increases in the frequency or severity of any effect between the exposed 

population and its appropriate control. 

levels of health concern in public water 

systems. EPA has made this 

determination by comparing the best 

available data on the occurrence of 

perchlorate in PWSs to potential health 

reference levels (HRLs) for perchlorate. 

HRLs are not final determinations about 

the level of a contaminant in drinking 

water that is necessary to protect any 

particular population. Rather they are 

benchmarks against which EPA 

compares the concentration of a 

contaminant found in public water 

systems to determine if it is at levels of 

public health concern. 

In January 2005, the National 

Research Council (NRC) published 

‘‘Health Implications of Perchlorate 

Ingestion,’’ a review of the state of the 

science regarding potential adverse 

health effects of perchlorate exposure 

and mode of action for perchlorate 

toxicity (NRC, 2005). The NRC 

recommended that EPA use data from 

the Greer et al. (2002) human clinical 

study as the basis for deriving a 

reference dose for perchlorate (NRC, 

2005). Although the NRC committee 

concluded that hypothyroidism is the 

first adverse effect in the continuum of 

effects of perchlorate exposure, NRC 

recommended that ‘‘the most healthprotective and scientifically valid 

approach’’ was to base the perchlorate 

RfD on the inhibition of iodide uptake 

by the thyroid, which the NRC 

considered a non-adverse effect (NRC, 

2005). The NRC recommended that EPA 

apply an intraspecies uncertainty factor 

of 10 to the no observed effect level 

(NOEL),1 to account for differences in 

sensitivity between the healthy adults in 

the Greer et al., (2002) study and the 

most sensitive population, fetuses of 

pregnant women who might have 

hypothyroidism or iodide deficiency. 

They viewed this as conservative and 

protective of health given that the NOEL 

is based on a non-adverse effect (iodide 

uptake inhibition), which precedes the 

adverse effect in a continuum of 

possible effects of perchlorate exposure. 

The NRC also noted that ‘‘any decrease 

(in thyroid hormone) is potentially more 

likely to have adverse effects in 

sensitive populations (people with 

thyroid disorders, pregnant women, 

fetuses, and infants). EPA’s Integrated 

Risk Information System (IRIS) adopted 

the NRC’s recommendations resulting in 

an RfD of 0.7 μg/kg/day (USEPA, 

2005b). 

In the October 2008 preliminary 

regulatory determination, EPA had 

derived a single HRL of 15 μg/L based 

upon the RfD, an estimate of perchlorate 

exposure from food for pregnant 

women, and traditional adult body 

weight (70 kg) and drinking water 

consumption (2 L/day) values. This 

single HRL was derived to reflect 

exposure to a pregnant woman and her 

fetus, which the NRC identified as ‘‘the 

most sensitive population.’’ 

Since the NRC also identified infants 

and developing children as additional 

life stages, EPA derived potential 

alternative HRLs for 14 life stages (age 

groups) using the RfD and life stagespecific exposure information in the 

August 9, 2009, notice (74 FR 41883; 

USEPA 2009b). These levels range from 

1 μg/L to 47 μg/L and are the 

concentrations of perchlorate in 

drinking water that may result in total 

perchlorate exposures (from food and 

water) greater than the RfD for 

individuals at each life stage. These 

HRLs are calculated based on 

individuals who consume an average 

amount of perchlorate from food (except 

for pregnant women where EPA used a 

90th percentile dietary intake estimate), 

but who consume equal or more water 

on a per body weight basis than 90 

percent of their cohorts. EPA is 

evaluating these potential alternative 

HRLs and considers them to be levels of 

public health concern for purposes of 

this determination. EPA has compared 

these values to the data provided by 

PWSs subject to the first Unregulated 

Contaminant Monitoring Rule (UCMR 

1). EPA collected and analyzed drinking 

water occurrence data for perchlorate 

from 3,865 PWSs between 2001 and 

2005 under the UCMR 1. The minimum 

reporting level (MRL) for perchlorate 

under the UCMR 1 was 4 μg/L. 

EPA found that 160 (approximately 

4.1 percent) of the 3,865 PWSs that 

sampled and reported had at least 1 

analytical detection of perchlorate (in at 

least 1 sampling point) at levels greater 

than or equal to the MRL of 4 μg/L. 

These 160 PWSs are located in 26 States 

and 2 territories. Of these 160 PWSs, 8 

are systems serving 10,000 or fewer 

people and 152 are systems serving 

more than 10,000 people. These 160 

systems reported 637 detections of 

perchlorate at levels greater than or 

equal to 4 μg/L, which is approximately 

11.3 percent of the 5,629 samples 

collected by these 160 PWSs and 

approximately 1.9 percent of the 34,331 

samples collected by all 3,865 PWSs. 

The average concentration of 

perchlorate for those samples with 

positive detections for perchlorate was 

9.85 μg/L and the median concentration 

was 6.40 μg/L. 

Table 1 presents the number and 

percentage of PWSs that reported 

perchlorate at levels exceeding various 

threshold concentrations. Note that the 

MRL for perchlorate under the UCMR 1 

was 4 μg/L. 

TABLE 1—PERCENT PUBLIC WATER SYSTEM ESTIMATES FOR PERCHLORATE ABOVE THRESHOLDS OF INTEREST

Threshold concentration a PWSs with at least 1 detection 

> threshold of interest 

PWS entry or sample points 

with at least 1 detection 

> threshold of interest b

4 μg/L ................................................................................................................... 4.0% 

(155 of 3,865) 

2.5% 

(371 of 14,987) 

6 μg/L ................................................................................................................... 2.5% 

(97 of 3,865) 

1.5% 

(219 of 14,987) 

9 μg/L ................................................................................................................... 1.5% 

(56 of 3,865) 

0.77% 

(115 of 14,987) 

13 μg/L ................................................................................................................. 0.93% 

(36 of 3,865) 

0.37% 

(56 of 14,987) 

14 μg/L ................................................................................................................. 0.85% 

(33 of 3,865) 

0.32% 

(48 of 14,987) 

19 μg/L ................................................................................................................. 0.62% 

(24 of 3,865) 

0.20% 

(30 of 14,987) 

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TABLE 1—PERCENT PUBLIC WATER SYSTEM ESTIMATES FOR PERCHLORATE ABOVE THRESHOLDS OF INTEREST— 

Continued 

Threshold concentration a PWSs with at least 1 detection 

> threshold of interest 

PWS entry or sample points 

with at least 1 detection 

> threshold of interest b

23 μg/L ................................................................................................................. 0.39% 

(15 of 3,865) 

0.13% 

(19 of 14,987) 

aAll occurrence measures in this table were conducted on a basis reflecting values greater than the listed thresholds. Five systems detected 

perchlorate levels equal to 4 μg/L and are therefore not presented in this table. 

Given the range of potential 

alternative HRLs, EPA has reversed its 

October 2008 preliminary determination 

not to regulate perchlorate in drinking 

water. Based on the data in Table 1 and 

the range of potential alternative HRLs, 

EPA has determined that perchlorate is 

known to occur or there is a substantial 

likelihood that it will occur with a 

frequency and at levels of public health 

concern. 

C. Is there a meaningful opportunity for 

the reduction of health risks from 

perchlorate for persons served by public 

water systems? 

Yes. EPA has made this determination 

based on a consideration of the best 

available peer reviewed science and 

data collected in accordance with 

accepted methods related to perchlorate 

occurrence in drinking water, the 

presence of perchlorate in foods, and 

the potential health effects of exposure 

to perchlorate. 

Table 2 presents EPA’s estimates of 

the population served by PWSs that 

were monitored under UCMR 1 for 

which the highest reported perchlorate 

concentration was greater than the 

thresholds identified in Table 1. EPA 

has determined that a NPDWR for 

perchlorate could reduce perchlorate 

exposures for these populations to 

levels below the potential alternative 

HRLs that EPA has identified as levels 

of public health concerns for purposes 

of this determination, and that such 

exposure reductions present a 

meaningful opportunity for the 

reduction of health risks for persons 

served by PWSs. 

Specifically, Table 2 presents EPA’s 

estimates of the population served by 

PWSs that were monitored under UCMR 

1 for which the highest reported 

perchlorate concentration was greater 

than the thresholds identified in Table 

1. The second column of Table 2 

presents a range of estimates of the 

population served by PWSs that had at 

least one sample with perchlorate 

concentrations greater than the 

threshold. The population range 

represents both a high end estimate, as 

well as a central value estimate. These 

population estimates were derived using 

the UCMR 1 monitoring data. The high 

end estimate of the population served 

drinking water above a threshold is 

derived by adding the entire system 

population of all PWSs in which at least 

one sample was found to contain 

perchlorate above the threshold. EPA 

considers this a high end estimate 

because it is based on the assumption 

that the entire system population is 

served water from the entry point that 

had the highest reported perchlorate 

concentration. In fact, many PWSs have 

multiple entry points into which treated 

water is pumped for distribution to their 

consumers. For the PWSs with multiple 

entry points, it is unlikely that the entire 

service population receives water from 

the one entry point with the highest 

single concentration. Therefore, EPA 

also provides a central value estimate of 

the population served water with 

perchlorate above a threshold in the 

second column in Table 2. EPA 

developed this central value estimate by 

assuming the population was equally 

distributed among all entry points and 

added only the proportion of the total 

population served by those entry points 

in a PWS that had at least one sample 

with perchlorate concentrations greater 

than the threshold. For example, if a 

PWS with 10 entry points serving 

200,000 people had a sample from a 

single entry point with a concentration 

at or above a given threshold, EPA 

assumed that the entry point served 

one-tenth of the PWS population, and 

added 20,000 people to the total when 

deriving the central value population 

estimate. In contrast, for the high end 

estimate using the example above, EPA 

added the entire PWS population of 

200,000 to the total population. The 

latter is likely an overestimate. The 

UCMR 1 population estimates in Table 

2 are for people at all life stages. 

TABLE 2—POPULATION ESTIMATES

FOR PWSS THAT DETECTED PERCHLORATE ABOVE VARIOUS THRESHOLDS

Threshold a

Range of population 

served by PWSs with at 

least 1 detection 

> threshold b

(million) 

4 μg/L ................... 5.1–16.6 

6 μg/L ................... 3.0–11.8 

9 μg/L ................... 1.6–5.2 

14 μg/L ................. 0.9–2.1 

19 μg/L ................. 0.7–1.6 

23 μg/L ................. 0.4–1.0 

aAll occurrence measures in this table were 

conducted on a basis reflecting values greater 

than the listed thresholds. All population estimates in this table are rounded. bPopulation estimates are derived from 

UCMR 1 data. 

D. Regulatory Determination 

EPA has determined that perchlorate 

meets the criteria for regulating a 

contaminant in Section 1412(b)(1)(A) of 

SDWA. As previously discussed in this 

regulatory determination, perchlorate 

may have an adverse effect on the health 

of persons and perchlorate is known to 

occur or there is a substantial likelihood 

that perchlorate will occur in public 

water systems with a frequency and at 

levels of public health concern. 

Moreover, in light of the discussion in 

this regulatory determination and the 

information available at this time, the 

Administrator finds that regulation of 

perchlorate in drinking water systems 

presents a meaningful opportunity for 

health risk reduction for persons served 

by public water systems. Therefore, EPA 

will initiate the process of proposing a 

NPDWR for perchlorate. 

E. Key Commenter Issues 

EPA received a total of approximately 

39,000 comments from individuals or 

organizations on the May 2007 

document, and the October 2008, and 

August 2009 Federal Register notices 

regarding the perchlorate regulatory 

determination. This section briefly 

discusses a number of the key issues 

raised by commenters and EPA’s 

response to these concerns. Responses 

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7766 Federal Register / Vol. 76, No. 29 / Friday, February 11, 2011 / Proposed Rules 

to all of the comments received are 

available in the ‘‘Comment Response 

Document for the Final Regulatory 

Determination on Perchlorate’’ (USEPA, 

2010a) available at http:// 

www.regulations.gov (Docket ID No. 

EPA–HQ–OW–2009–0297). 

1. Health Implications of Perchlorate 

Exposure Above the RfD 

EPA received comments indicating 

that the levels of perchlorate in drinking 

water that result in exposures greater 

than the RfD are not levels of public 

health concern because the RfD is based 

on a precursor to an adverse effect. EPA 

believes the NRC appropriately based 

the RfD on iodide uptake inhibition to 

the thyroid, for the reasons discussed in 

its report. EPA also received a 

substantial number of comments 

supporting the Agency’s current view. 

EPA notes that the data underlying the 

definition of iodide uptake inhibition as 

a precursor effect and the relationship of 

iodide uptake inhibition to the 

continuum of adverse outcomes reflects 

an understanding of effects in adults; it 

may not reflect the relationship of the 

precursor event to adverse outcomes in 

neonates and infants, who may not have 

iodide stores sufficient to offset the 

effects of reduced iodide uptake. The 

less resilient neonatal and infant system 

makes the exposure gap between a 

precursor event (iodide uptake 

inhibition due to perchlorate) and 

reduced T3/T4 levels likely to be 

narrower than for adults, and in fact, the 

distinction between the two may be 

blurred for the very young (Greer et al., 

2002; Savin et al., 2003; van den Hove 

et al., 1999). The NRC noted that, ‘‘[T]he 

minimal prolonged decrease in thyroid 

hormone production that would be 

associated with adverse health effects is 

not known; any decrease is potentially 

more likely to have adverse effects in 

sensitive populations (people with 

thyroid disorders, pregnant women, 

fetuses, and infants) but data are not 

available to determine the magnitude of 

the decrease needed to cause adverse 

effects in those populations.’’ 

2. Other Thyroid Inhibiting Chemicals 

EPA received a number of comments 

that the Agency should consider the 

comparative effect on iodine uptake of 

perchlorate exposure in drinking water 

to nitrate and thiocyanate exposure in 

drinking water in determining whether 

there is a meaningful opportunity for 

risk reduction. Other commenters, 

including EPA’s Office of Inspector 

General (USEPA, 2008c), believe that a 

NPDWR for a group of chemicals may be 

appropriate based on a yet-to-beconducted cumulative risk assessment 

that assesses and characterizes the 

combined human health risk from 

perchlorate, nitrate, and thiocyanate. 

While EPA acknowledges that nitrate 

and thiocyanate have the same mode of 

action as perchlorate, and that the 

effects of combined exposure to 

perchlorate, nitrate, and thiocyanate are 

additive, EPA does not believe there are 

sufficient scientific data currently 

available to assess and characterize the 

combined risk of these contaminants. 

EPA has committed to a drinking water 

strategy that outlines four principles to 

expand public health protection for 

drinking water (USEPA, 2010b). One of 

these principles is to address 

contaminants as groups. However, EPA 

does not believe that regulatory action 

to address perchlorate should be further 

delayed. Therefore, EPA intends to 

develop a proposed rule for perchlorate. 

At such time as a NPDWR is 

promulgated, EPA is required to review 

and revise, as appropriate, its drinking 

water standards at least every six years. 

Any revision must at least maintain or 

improve public health protection. When 

there are sufficient scientific data to 

assess the cumulative risks of 

perchlorate and other contaminants, 

EPA will review this information to 

evaluate whether any revisions of 

NPDWRs are appropriate. 

3. Perchlorate in Food 

A commenter wrote that a drinking 

water regulation for perchlorate does 

not present a meaningful opportunity 

for health risk reduction because 

perchlorate contamination in food is 

widespread. Other commenters 

indicated that EPA should regulate 

perchlorate in drinking water to reduce 

the public’s overall exposure to 

perchlorate. EPA agrees that perchlorate 

contamination is more widespread in 

foods than in PWSs; however, EPA does 

not believe that the widespread 

presence of perchlorate in food 

overrides the need for public health risk 

reduction for persons served by PWSs 

with perchlorate contamination. The 

Agency presented an extensive 

evaluation of dietary exposure to 

perchlorate in the October 2008 and 

August 2009 notices (73 FR 60262; 

USEPA 2008a and 74 FR 41883; USEPA 

2009b). EPA has used this dietary 

exposure data to account for the relative 

source contribution (RSC) of perchlorate 

from food to estimate the range of levels 

of public health concern. EPA 

recognizes that a drinking water 

regulation would not eliminate total 

perchlorate exposure, but believes that 

the reduction in perchlorate exposure in 

drinking water presents a meaningful 

opportunity for health risk reduction for 

persons served by PWSs contaminated 

by perchlorate. 

4. Iodide Nutritional Status 

Some commenters stated that public 

health concerns over iodide uptake 

inhibition could be addressed more 

efficiently through promotion of iodide 

nutrition than through regulation of 

perchlorate. EPA agrees that promoting 

iodide nutrition is good public health 

policy and may have a positive 

influence in reducing the iodide uptake 

inhibition effects associated with 

exposure to perchlorate. However, the 

Agency does not think it is appropriate 

to rely on the promotion of iodide 

nutrition in this case, especially since 

these activities are outside of EPA’s 

SDWA authority. As a result, while the 

health concerns associated with 

perchlorate may be addressed through 

other means, it is the Administrator’s 

judgment that a standard limiting 

perchlorate in drinking water can 

reduce health risk, particularly to 

fetuses, infants and children. 

5. Physiologically-Based 

Pharmacokinetic (PBPK) Modeling 

EPA reviewed, modified, and applied 

the perchlorate PBPK models, which 

were originally developed by Merrill et 

al. (2005) for adults and Clewell et al. 

(2007) for other life stages, to estimate 

the iodide uptake inhibition in the 

thyroid for each life-stage (73 FR 60262; 

USEPA 2008a). Estimated ingestion 

rates were then used to estimate the 

internal dose and resulting iodide 

uptake inhibition for several life stages, 

including susceptible populations (e.g., 

pregnant women and their fetuses, as 

well as breast-fed and bottle-fed 

infants). 

In the August 2009 notice, EPA stated 

that it was re-evaluating how best to 

incorporate the PBPK modeling analysis 

into its evaluation of perchlorate—if at 

all. The Agency sought comments on 

ways to use the PBPK modeling analysis 

to inform the regulatory determination. 

Several commenters supported the 

use of the PBPK model to inform the 

regulatory determination only if the 

significant limitations of the current 

model are addressed. For example, the 

inability of the model to reflect iodide 

nutritional status was cited by 

commenters and three of four peer 

reviewers as an important limitation 

(USEPA, 2008d). Also, several 

commenters stated that the risks to 

breast-fed infants and young children 

are not adequately addressed by the 

model. They challenged that the 

modeling analysis is based on average 

weight infants and healthy adults, while 

the sensitive life stages for perchlorate 

mstockstill on DSKH9S0YB1PROD with PROPOSALS

Federal Register / Vol. 76, No. 29 / Friday, February 11, 2011 / Proposed Rules 7767 

2On January 8, 2009, EPA issued an interim 

health advisory to provide guidance to State and 

local officials in their efforts to address perchlorate 

contamination. The interim health advisory 

(USEPA, 2008e) can be found at: http:// 

www.epa.gov/safewater/contaminants/unregulated/ 

pdfs/healthadvisory_perchlorate_interim.pdf and in 

EPA’s docket ID No. EPA–HQ–OW–2009–0297 for 

this notice. EPA expects to make a final decision 

on the interim health advisory at such time as a 

definitive decision has been made with respect to 

the promulgation of a final perchlorate regulation. 

include premature infants and 

hypothyroid women. 

After further consideration of the peer 

review and public comments, EPA 

concludes that the PBPK modeling 

analysis, in the context of the 

perchlorate regulatory determination, is 

useful in examining which life stages 

are most susceptible to the effects of 

perchlorate. For example, the model 

indicates that a fetus may be seven 

times more sensitive to the effects of 

perchlorate than a pregnant woman. The 

model also allows for the estimation of 

the concentration of perchlorate in 

breast milk (thus breast-fed infant 

exposure) at various maternal 

perchlorate exposure levels. However, 

because of the stated limitations, EPA 

has decided the model does not directly 

bear on the current decision regarding 

the need for a NPDWR for perchlorate. 

EPA is continuing to evaluate whether 

the model could be used in setting a 

NPDWR for perchlorate. 

F. Next Steps 

EPA is initiating the development of 

a proposed NPDWR for perchlorate. 

However, this is not the end of a 

decision process but a middle step in a 

process that leads to a final drinking 

water standard. Based on this decision, 

EPA intends to publish a proposed 

NPDWR for public review and comment 

within 24 months of this regulatory 

determination.2 EPA will continue to 

evaluate the science as we develop the 

proposed NPDWR. EPA will, as part of 

the proposed NPDWR, present a health 

risk reduction and cost analyses, an 

analysis of feasible treatment methods, 

and an analysis of small system 

compliance technologies. EPA will also 

consult with the National Drinking 

Water Advisory Council, the Science 

Advisory Board, and the Secretary of 

Health and Human Services, as required 

under SDWA. 

IV. References 

Clewell, R.A., E.A. Merrill, J.M. Gearhart, P.J. 

Robinson, T.R. Sterner, D.R. Mattie, and 

H.J. Clewell, III. 2007. Perchlorate and 

radioiodide kinetics across life stages in 

the human: Using PBPK models to 

predict dosimetry and thyroid inhibition 

and sensitive subpopulations based on 

developmental stage. Journal of 

Toxicology and Environmental Health. 

Part A. Vol. 70. Issue 5. p. 408–428. 

Greer, M.A., G. Goodman, R.C. Pleuss, and 

S.E. Greer. 2002. Health effect 

assessment for environmental 

perchlorate contamination: The dose 

response for inhibition of thyroidal 

radioiodide uptake in humans. Environ 

Health Perspect Vol. 110. p. 927–937. 

Life Sciences Research Office (LSRO), 

Federation of American Studies for 

Experimental Biology Prepared for the 

Interagency Board for Nutrition 

Monitoring and Related Research. 1995. 

Third Report on Nutrition Monitoring in 

the United States: Volume 1. U.S. 

Government Printing Office, 

Washington, DC. 

Merrill, E.A., R.A. Clewell, P.J. Robinson, 

A.M. Jarabek, T.R. Sterner, and J.W. 

Fisher. 2005. PBPK model for radioactive 

iodide and perchlorate kinetics and 

perchlorate-induced inhibition of iodide 

uptake in humans. Toxicological 

Sciences. Vol. 83. p. 25–43. 

National Research Council (NRC). 2005. 

Health Implications of Perchlorate 

Ingestion. National Academies Press, 

Board on Environmental Studies and 

Toxicology. January 2005. p. 276. 

Savin, S., D. Dvejic, O. Nedic, R. 

Radosavljevic. 2003. Thyroid Hormone 

Synthesis and Storage in the Thyroid 

Gland of Human Neonates. J. Pediatric 

Endocrinology & Metabolism. Vol. 16. p. 

521–528. 

U.S. Census Bureau. 2008. U.S. Census 

Bureau Annual Estimates of Resident 

Population by Single-Year of Age and 

Sex for the U.S. and States: April 2, 2000 

to July 1, 2008. Available on the Internet 

at: http://www.census.gov/popest/states/ 

asrh/. 

USEPA. 1998. Announcement of the 

Drinking Water Contaminant Candidate 

List; Notice. Federal Register. Vol. 63, 

No. 40. p. 10273, March 2, 1998. 

USEPA. 2004. Estimated Per Capita Water 

Ingestion and Body Weight in the United 

States—An Update. Office of Science 

and Technology, Washington, DC; 

EPA/822/R–00–001. 

USEPA. 2005a. Drinking Water Contaminant 

Candidate List 2; Final Notice. Federal 

Register. Vol. 70, No. 36. p. 9071, 

February 24, 2005. 

USEPA. 2005b. ‘‘Integrated Risk Information 

System (IRIS), Perchlorate and 

Perchlorate Salts.’’ February 2005. 

Available on the Internet at: http:// 

www.epa.gov/iris/subst/1007.htm. 

Accessed February 2, 2005. 

USEPA. 2007. Drinking Water: Regulatory 

Determinations Regarding Contaminants 

on the Second Drinking Water 

Contaminant Candidate List— 

Preliminary Determinations, Federal 

Register, Vol. 72, No. 83. p. 24016, May 

1, 2007. 

USEPA. 2008a. Drinking Water: Preliminary 

Regulatory Determination on 

Perchlorate, Federal Register, Vol. 73, 

No. 198. p. 60262, October 10, 2008. 

USEPA. 2008b. Child-Specific Exposure 

Factors Handbook. National Center for 

Environmental Assessment, Washington, 

DC; EPA/600/R–06/096F. 

USEPA. 2008c. Scientific Analysis of 

Perchlorate (External Review Draft). 

Office of Inspector General, Washington, 

DC; Assignment No. 2008–0010. 

Available on the Internet at: http:// 

www.epa.gov/oig/reports/2010/ 

20100419-10-P-0101.pdf. 

USEPA. 2008d. Comment Response 

Summary Report, Peer Review of 

Drinking Water Health Advisory for 

Perchlorate. Office of Science and 

Technology, Washington, DC; December 

2008. 

USEPA. 2008e. Interim Drinking Water 

Health Advisory for Perchlorate. Office 

of Science and Technology, Washington, 

DC; EPA 822–R–08–025. 

USEPA. 2009a. Drinking Water Contaminant 

Candidate List 3—Final. Federal 

Register. Vol. 74, No. 194. p. 51850, 

October 8, 2009. 

USEPA. 2009b. Drinking Water: Perchlorate 

Supplemental Request for Comments, 

Federal Register, Vol. 74, No. 159. p. 

41883, August 19, 2009. 

USEPA. 2010a. Comment Response 

Document for the Final Regulatory 

Determination on Perchlorate 

(Categorized Public Comments). EPA 

XXX–XXX. December, 2010. 

USEPA. 2010b. A New Approach to 

Protecting Drinking Water and Public 

Health. EPA 815–F–10–001. Available on 

the Internet at: http://water.epa.gov/ 

lawsregs/rulesregs/sdwa/dwstrategy/ 

index.cfm 

van den Hove, M.F., C. Beckers, H. Devlieger, 

F. de Zegher, P. De Nayer. 1999. 

Hormone synthesis and storage in the 

thyroid of human preterm and term 

newborns: Effect of thyroxine treatment. 

Biochimie. Vol. 81. p. 563–570. 

Zimmerman, M. 2009. Iodide Deficiency. 

Endocrine Reviews. Vol. 30, No. 4. p. 

376–408. 

Dated: February 2, 2011. 

Lisa P. Jackson, 

Administrator. 

[FR Doc. 2011–2603 Filed 2–10–11; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF HEALTH AND 

HUMAN SERVICES 

45 CFR Parts 144 and 147 

[CMS–9981–P] 

RIN 0950–AA20 

Student Health Insurance Coverage 

AGENCY: Centers for Medicare & 

Medicaid Services (CMS), HHS. 

ACTION: Proposed rule. 

SUMMARY: This document contains a 

proposed regulation that would 

establish rules for student health 

insurance coverage under the Public 

Health Service Act and the Affordable 

Care Act. The proposed rule would 

define ‘‘student health insurance 

mstockstill on DSKH9S0YB1PROD with PROPOSALS