United States
             Environmental Protection
             Office of
             Drinking Water
             Washington DC 20460
Criteria & Standards Division
State Programs Division
May 1979
WSG 61
for the
Issuance of

                     TABLE OF CONTENTS
Preface	i
Section I: Conditions for Granting Variances and
Section II: "Economic Factors for Granting Exemptions,"
  Guidelines for Determination
Section III: "Unreasonable Risk to Health," Guidelines
  for Determination

    A. Bacteriological	III-2
    B. Turbidity	III-2
    C. Inorganic Chemicals	III-3
        1. Arsenic	III-3
        2. Barium	III-5
        3. Cadmium	III-7
        4. Chromium	III-9
        5. Fluoride	Ill-10
        6. Lead	III-12
        7. Mercury.	111-14
        8. Nitrate	III-1 6
        9. Selenium	111-19
       10. Silver	111-20
    D. Organic Compounds	111-21
        1. 2,4-D	111-21
        2. 2,4,5-TP	111-24
        3. Toxaphene	111-27
        4. Methoxychlor	111-29
        5. Endrin	111-31
        6. Lindane	111-33

E • Radionuclides................................. .111—36
1. Combined Radium—226 and Radium—228........III—36
2. Gross Alpha Particle Activity.............III—38
3. Man—Made Beta and Photon Emitters.........III—39
Section IV: Variance and Exemption Procedures
Section V: Compliance Agreements

This document contains guidance for the issuance of
variances and exemptions under Sections 1415 and 11416 of the
Safe Drinking Water Act, as amended (142 U.S.C. § 300 f et
s q.) and the regulations implementing those provisionsTSee
1FO CFR Section 1141.14). This guidance is intended to be used
by States with primary enforcement responsibility (primacy)
and EPA Regional Offices that issue variances and exemptions
in those States that have not been granted primacy. For the
purpose of this document, they will be collectively referred
to as the “primacy agency.”
Variances and exemptions are authorized to be issued by
a primacy agency to a public water system that is not
immediately able to comply with a maximum contaminant level
(MCL) or treatment technique requirement established in the
National Interim Primary Drinking Water Regulations
(NIPDWR). No variances or exemptions may be granted from
monitoring requirements under the NIPDWR. The NIPDWR
presently in effect, 140 CFR Part 1141, specify MCLs for a
number of contaminants including turbidity, microbiological
contaminants, inorganic and organic chemicals, and radionu-
clides. They do not presently prescribe any treatment
techniques which are also authorized under Section 11412 of
the Act. Therefore, this document will be limited to a
discussion of variances and exemptions from MCLs prescribed
under the NIPDWR. A separate guidance will be issued for
variances and exemptions from a treatment technique should
one be prescribed in any amendment to the NIPDWR.
In providing the primacy agency with the authority to
issue variances and exemptions from the NIPDWR, Congress
recognized that not all public water systems would be able
to achieve compliance with the regulation by the effective
date. It was assumed that two different kinds of problems
would be encountered by public water systems required to
comply with the NIPDWR, and variances and exemptions were
intended to address these problems separately.
First, a public water system might be unable to achieve
compliance with an applicable MCL due to poor source water
quality, despite application of the most effective treatment
methods. In such rare situations, the primacy agency would
be authorized to grant a variance to that public water

The second, and more common situation, would be where
the public water supply was unable to comply with an
applicable MCL due to compelling factors such as economic
constraints which may include the high cost of purchasing
and constructing necessary equipment or facilities and/or
the low per capita income and small number of residents in a
community served by the system. The granting of an
exemption would be authorized under these latter
The distinction between variances and exemptions is
important for two reasons. First, new systems are only
eligible to apply for a variance. Before an exemption may
be granted, Section 1416(a) (2) of the Act requires that the
primacy agency find that “the public water system was in
operation on the effective date” of any MCL or treatment
technique requirement.
Thus, Congress intended that compelling factors, such as
economics, would not be used to enable a new system to
commence operation without first being in full compliance
with the applicable requirements. On the other hand, a
variance could still be appropriate where a new system is
unable to comply with the effective regulations despite the
application of best technology due to poor source water
The distinction between variances and exemptions is also
important because of the different compliance time tables
established by Congress. Both variances and exemptions must
be accompanied by the issuance of a compliance schedule
within one year. The compliance schedule must require that
the public water system come into compliance with the appli-
cable MCL as expeditiously as practicable (as determined by
the primacy agency). Whereas the compliance schedule for an
exemption requires compliance by no later than January 1,
1981, (or January 1, 1983, if a public water system has
entered into an enforceable agreement to become part of a
regional public water system), no such statutory deadline is
imposed for variances.
A variance is issued to a public water system whose
source water is of such poor quality that it may not be
possible to dictate when technology will become generally
available to bring that system into compliance. Therefore,
it may not be possible to set a compliance deadline for such
a system. However, Congress intended that an exemption
specify a time limit for compliance on the assumption that
compelling factors such as economic hardship could be miti-
gated over a period of time. EPA recognizes the problems

which the exemption deadlines may pose particularly to small
water systems, and accordingly is asking Congress to extend
the time limit for exemptions. In the interim, compliance
schedules for exemptions must attempt to achieve compliance
in the shortest possible time and may not extend longer than
the statutory deadline. However, this schedule may reflect
a review date at which time the primacy agency can revise
the deadlines should the statute be amended.
Variances and exemptions were not intended to be used as
means for easily or indefinitely delaying compliance with
the NIPDWR. Congress specifically required the primacy
agency to make the finding that the issuance of either a
variance or exemption would not result in an unreasonable
risk to the health of the persons served by the system. In
addition, the public water system is required to give public
notification pursuant to Section 1 1 (c) of the Act of the
existence of each variance or exemption and any failure to
comply with the requirements of any compliance schedule
issued therewith. The compliance schedule itself must
contain interim control measures and increments of progress
to be followed by the public water system while such
variance or exemption is in effect. Any requirement of a
schedule on which a variance or exemption is conditioned may
be enforced as if such requirement were a part of a NIPDWR.
In return for the public water system’s compliance with
these requirements, the issuance of a variance or exemption
to a public water system otherwise in violation of an MCL
under the NIPDWR, protects that system from enforcement
action under Section i 14 as well as from “citizen suits”
under Section 1 9 of the Act.
Finally, under Section 1 4 8(b) of the SDWA, the granting
of, or the refusing to grant a variance or exemption, the
requirements of any schedule for a variance or exemption and
the failure to prescribe a schedule are subject to judicial
review in the United States district courts. EPA also com-
prehensively reviews State—issued variances and exemptions
at best every three years to assure that the State has not
abused its discretion in granting variances and exemptions
and has not failed to impose reasonable control measures.
For purposes of these reviews, it is critical that the
primacy agency carefully document the bases for its
deter mi nat i o n.
This document is intended to assist in the development
of uniform interpretations and protocols for issuance of
variances and exemptions and for application of the NIPDWR.
It will also serve as the basis for EPA ’s review of
State—issued variances and exemptions.

This guidance for granting variances and exemptions will
discuss the following issues in turn:
I. Conditions for Granting Variances and Exemptions —
This section will discuss the fundamental conditions for the
granting of variances and exemptions from MCLs.
II. Economic Criteria for Granting Exemptions - One
criterion for granting an exemption is the existence of
compelling economic hardship. This section discusses the
specific procedures for making a determination as to whether
“compelling economic factors” exist to justify the granting
of an exemption.
III. Unreasonable Risk to Health - The granting of a
variance or exemption from an MCL must not result in an
unreasonable risk to the health of consumers served by the
public water system. This section will provide guidance
that may be used in making this determination.
IV. Variance and Exemption Procedures - The procedures
that must be followed by States in granting variances and
exemptions are set forth under Section 1 l15 and 1416 of the
Act and O CFR Part 1 42 Subpart C. kO CFR 1112.kO and
§ 142.50 set forth procedures to be followed by EPA where it
retains primary enforcement responsibility. This section
will discuss these procedures, generally providing flow
diagrams as an aid to understanding. The issuance of
compliance schedules will be discussed in detail.
V. Compliance Agreements — This section discusses an
administrative tool that can be used in certain situations
where it would be impractical to fully implement the exemp-
tion process. Guidance is given on procedures to implement
this administrative tool.

Variances from MCLs
Section 1’ 15(a)(1)(A) of the Safe Drinking Water Act
authorizes the primacy agency to grant variances from MCLs
to public water systems which:
because of characteristics of the raw water sources
which are reasonably available to the systems,
cannot meet the requirements respecting the MCLs of
such drinking water regulation despite application
of the best technology, treatment techniques, or
other means, which the Administrator finds are
generally available (taking costs into
consideration.) (Emphasis added).
In addition, the primacy agency must make a finding before
the variances may be granted that the variances will not
result in an unreasonable risk to health.
The language of this section as well as the legislative
history make clear that the essential basis for the granting
of a variance to a public water system is the quality of the
raw water sources reasonably available to that system.
Under Section 1L 12 of the Act, Congress intended for MCLs
under the NIPDWR to be established at such levels which
could be achieved by large systems with relatively uncontam-
inated raw water sources. Congress explained its rationale
for this assumption as follows:
If the Administrator were to assume that intake
waters would in general be extremely contaminated,
then many areas which are relatively clean could
meet the maximum contaminant levels which the
Administrator would prescribe without the use of
the most effective treatment methods. This result
would be inconsistent with the Committee’s
overriding intent to maximize protection of the
public health. (House Report No. 93—1185, p. 12).
However, Congress also recognized that, in some
instances, public water systems with extremely contaminated
intake water sources would be unable to comply with the MCLs
even after installing the technology determined by the
Administrator to be generally available when the MCLs were

established. Variances were therefore authorized to be
granted in such cases.
To qualify for a variance from an MCL, a public water
system must demonstrate to the primary agency that it satis-
fies the following two conditions:
1. The application of treatment methods, generally
available at a reasonable cost to large systems, has not
esulted in compliance with the MCL due to poor source water
guality, and the system has made all other reasonable tech-
nological, economic and legal efforts to comply with the
It is important to note that the system must have the
“generally available” treatment in place and operational in
order to demonstrate that non—compliance is due to poor
source water quality and thereby to be eligible for a
variance. In addition, the primacy agency should ensure
that the system has made all reasonable efforts to obtain
access to an alternative, less contaminated raw water
source. The system may be able to improve its raw water
quality through identification and elimination of the cause
of contamination. Reasonable technological solutions such
as improvement of existing treatment operation and
efficiency should also be explored. The primacy agency
should periodically review variances after they are issued
to assure that they are still necessary and that all
reasonable efforts to obtain access to a satisfactory raw
water source are being made by the system. (See also
discussion of compliance schedules under Section IV of this
2. Issuance of the variance will not result in an
unreasonable risk to health .
The determination of whether or not the issuance of a
variance will result in an unreasonable risk to the health
of consumers served by the system must take into account the
nature of the contaminant and the degree of contamination in
a particular case. Guidance for making this determination
is contained in Section III of this document.
* Variances are expected to be granted relatively
infrequently since available treatment methods should
ordinarily be effective. See EPA ’s Manual of Treatment
Techniques for Meeting the Interim Primary Drinking Water
Regulations. This manual lists treatment methods for
specific contaminants for which MCLs have been established
in the National Interim Primary Drinking Water Regulations.

Exemptions from MCLs
Section 1416(a) of the Safe Drinking Water Act
authorizes the primacy agency to grant an exemption from an
MCL based upon a finding that:
(1) due to compelling factors (which may include
economic factors), the public water system is unable to
comply with such contaminant level,
(2) the public water system was in operation on the
effective date of such contaminant level, and
(3) the granting of an exemption will not result in an
unreasonable risk to health.
Congress recognized that some public water systems would
not be able to achieve compliance with the MCLs by the
effective date of the regulations. Because the MCLs were
established based upon technology reasonably available to
large systems, it was anticipated that small systems might
experience particular hardship in meeting the standards.
(See House Report No. 93—1185, p. 18). In order to provide
systems faced with problems related to economic and techno-
logical feasibility more time to achieve compliance,
exemptions were authorized to be granted. However, specific
time deadlines were imposed by the Act by which time such
systems were required to be in compliance. (See discussion
of compliance schedules in Section IV of this document). In
addition, the Act imposed the following three conditions for
the granting of an exemption by the primacy agency:
1. The system is unable to comply with an MCL due to
economic or other compelling factors .
The existence of compelling factors is the principal
criterion for determining whether a public water system
should be granted an exemption. Such compelling factors are
most likely to be economic factors, such as not being able
to afford the treatment necessary to achieve compliance with
the MCL. This could be because of the high cost of purchas-
ing and constructing and operating necessary equipment or
facilities, or the low per capita income and small number of
residents in a community served by the system. The system
might also encounter unavoidable delays or other
technological problems in installation or operation of the
necessary treatment equipment which would prevent a system
from achieving compliance by the effective date of the MCL.

I— 4
The primacy agency should exercise its exemption
authority in a responsible manner, especially if a system
would be forced to terminate service in the absence of an
exemption. However, it is also essential during the period
of the exemption, that the system be required to find
solutions to its problems such as the development of a
regional water system which could afford to purchase and
operate the necessary treatment technology, to seek
additional sources of funding such as State or Federal
financial assistance, and to explore alternative raw water
supplies. The compliance schedule issued by the primacy
agency should incorporate those steps which the system must
take to meet the MCLs. (See Section IV of this document).
More detailed guidance on the economic factors that
should be considered by the primacy agency in determining
whether to grant an exemption is contained in Section II of
this document. As a basic principle, however, Congress
expected public water systems to use available funds to
achieve compliance with the MCLs rather than for substantial
expansion of capacity or service. Thus, the House Report
In the Committee’s view, if a system has sufficient
funds to permit substantial expansion of capacity
and service, these funds should first be used to
assure the safe quality of the drinking water
presently being supplied. In such cases, States
should be extremely reluctant to grant exemptions
on economic grounds. (House Report No. 93-1185, p.
2. The system must have been in operation when the
applicable MCL went into effect .
This condition basically prohibits the primacy agency
from granting an exemption to a new system, that is, a
system which begins operation after the effective date of
the regulation. This was clearly intended to require all
new systems to be in compliance with all applicable require-
ments before they became operational. This is consistent
with Congress’ expressed reluctance to grant exemptions on
economic grounds where the substantial expansion of’ existing
facilities of a system are planned.
3. Granting of the exemption will not result in an
unreasonable risk to hea11 h .
The determination of whether or not the granting of an
exemption will result in an unreasonable risk to the health

of consumers served by the system must take into account the
nature of the contaminant and the degree of contamination in
a particular case. Guidance for making this determination
is contained in Section III of this document.

“Economic Factors for Granting Exemptions”
Guidelines for Determination
One of the prerequisites to granting an exemption to a
public water system is that the primacy agency make a
finding that the public water system is unable, due to
compelling factors, including economic factors, to comply
with an established maximum contaminant level.
The decisions which lead to this finding are indicated
in the attached Diagram A and constitute the areas where the
primacy agency will have to apply case by case analysis.
Each is discussed below.
1. Is there a significant risk to health ?
Handled on an individual MCL basis, guidance on this
decision is contained in Section III.
2. Is the addition of the necessary treatment the best
alternative for the system ?
Treatment alternatives are discussed in several
documents, including “State of the Art of Small Water
Treatment Systems” (August 1977) and “Estimating Costs for
Water Treatment as a Function of Size and Treatment Plant
Efficiency” (EPA—600/2—78—182, August 1978).
In many cases the most desirable alternative will be the
least costly alternative, including consideration of alter-
native water sources. However, other factors such as water
quality parameters, quantity needs, and personnel
requirements must also be considered.
The water supplier making application for an exemption
should indicate alternatives considered, and reasons for his
selection. For small water supplies, Regions and States can
be expected to provide technical assistance in the
evaluation of the alternatives which might be used.
3. Are the financial constraints to system
implementation of the best alternatives due to
political, legal or technical obstacles ?
There are legitimate financial constraints which may be
due to political, legal or technical reasons.

I 1—2
Political obstacles which impose real financial
constraints tend to include the inability to pass bond
referenda, or other capital raising activities which require
voter approval, and dependence upon water revenues for
non—water public services. Such obstacles do not
immediately justify the issuance of an exemption. For
communities which must develop new funding to replace water
revenues for other community services when water revenues
are used to upgrade the water supply facility, it is
expected that an appropriate compliance schedule would
consider the community’s public service commitments as well
as its water supply needs. Evidence of either kind of
obstacle should be presented with the application for
Legal obstacles tend to revolve around changes in local
charters or time consuming approval requirements associated
with capital or revenue—raising activities. An adequate
description of these constraints could affect a system’s
compliance schedule. For example, if amendments to existing
ordinances must be made prior to implementing the changes
that will bring the system into compliance, the exemption
compliance schedule should include a reasonable time
necessary to draft, propose, hold public hearings and pass
amendments in addition to the time required to get necessary
fundings and complete the construction or modification.
Occasionally, the water supply or municipality may be
under legal challenge to halt or alter proposed improve-
ments to its water supply (including rate changes). It may
be desirable for the primacy agency to investigate the
desirability of filing briefs on behalf of one party or the
other. In any case, such an obstacle to system improvement
may have financial considerations which could reasonably
warrant an exemption.
Technical obstacles tend to dissolve if sufficient
capital and operating revenue is generated, and as such are
not prohibitive constraints. However, on rare occasions,
extreme conditions impose virtually prohibitive situations.
For example, analysis of upstream discharges may be extreme—
ly expensive yet control at that point of upstream discharge
may be the best alternative for compliance. As such, there
may be occasions when a compliance schedule must reflect
these special circumstances.
1 L Has the system investigated all possible sources of
funds ?
The Federal financial aid programs are described in the
“Catalog of Federal Domestic Assistance.” Some States also
provide grants and loans to public water systems.

II— 3
Applicants should demonstrate that they have investi-
gated these sources of funding when applying for an
5. Will system customers undergo financial hardships ?
Assessment of financial hardship requires some basic
kinds of information. Systems should provide data on (a)
annual capital requirements, (b) annual O&M requirements,
(c) annual revenue requirements associated with system
improvement for compliance, (d) financing opportunities (in
dollars available), Ce) system indebtedness, U ’) number of
outstanding unpaid bills as a percent of total bills, (g)
old and new annual family water bills (based on 3 people per
family) and (h) median family income for the service area.
Based on this information, the primacy agency can
determine if a supply can finance system improvements.
Having determined that financing opportunities exist, the
primacy agency must determine the hardship that such
financing may pose on consumers.
The level at which the water bill is determined to be an
economic burden relative to median family income involves a
critical policy decision. The basic criterion in use by
most Federal agencies is that the annual water bill should
not exceed a set percentage of the median family income.
Figures from .7 percent to 2 percent have been used by
various agencies. EPA uses 2 percent for its construction
grants program. FmHA is currently considering changing its
disputed 1 percent debt service guideline to a measure
similar to the 2 percent total bill guideline. However, for
areas where annual median family income is low, perhaps as
low as $5500, even the 2 percent figure may be onerous. The
Office of Drinking Water cannot specify an exact number, but
believes that for communities with an annual median family
income greater than about $8,000, the 2 percent figure does
not constitute a hardship. Below that income level, serious
consideration should be given to a lower number. This
economic consideration is under review at the present time;
this section will be revised upon completion of the review.
General Guidance
In all cases, it is the intent of Congress to improve
the quality of drinking water, but not at the expense of
closing down water supplies. Therefore, exemptions should
be responsive to the actual situation that exists as docu-
mented by evidence presented by a water supplier. Where

II— 4
there simply are no financing opportunities, compliance
schedules should be written to encourage speedy development
of needed resources. Where hardship exists, compliance
schedules should be written to account for longer term
improvements. Any compliance timetable must also, of
course, take into account the health risk posed to consumers
during the exemption period (See Section III of this
In considering if economic factors are sufficiently
compelling to warrant an exemption, consideration must be
given to any planned expansion of existing facilities of the
system. It was the view of the Congressional Committee, as
stated in the House Report 93—1185, page 27, that “... if a
system has sufficient funds to permit substantial expansion
of capacity and service, these funds should first be used to
assure the safe quality of’ the drinking water presently
being supplied. In such cases, States should be extremely
reluctant to grant exemptions on economic grounds.” This
principle should be adhered to in making a decision on
economic hardship.

In order to obtain a variance or an exemption from an
MCL, a public water system must demonstrate that the
variance or exemption will not result in an unreasonable
risk to health. When the absence of an unreasonable risk to
health has been or can be reasonably determined, variances
or exemptions can be granted within the limitations
recommended herein. For those cases where the MCL has been
exceeded to a greater degree than provided for in this
section, and for cases where there is doubt as to the
reasonableness of the risk to health, the Office of Drinking
Water should be consulted. An exemption committee within
that Office will provide assistance in these cases, thus
assuring national consistency in the interpretation of the
phrase, “unreasonable risk to health. tl
Any violation of an MCL, by definition, creates some
increased risk to the public health . The pertinent issue,
though, for purposes of’ granting variances or exemptions
from an MCL is whether the resultant increased risk is
adjudged to be unreasonable . In any determination of
unreasonableness of risk, at least the following should be
(a) The degree to which the MCL is being or will be
exceeded during the exemption or variance period and the
adverse chronic or acute health effects resulting therefrom.
(b) The duration of the requested variance or exemption
(i.e., the longer the duration, the greater the risk).
(c) Historical data (how long the problem has existed in
the subject water supply) and whether any adverse effects
attributable to water may have occurred.
(d) The population exposed (i.e. particularly
susceptible individuals such as the very young or old or
1 The references cited within this document can be
found in the National Academy of Sciences Safe Drinking
Water Committee Publication, “Drinking Water and Health,
(1977).” More detailed discussion of the material contained
herein can also be found in that publication.

In order to minimize the risk to health after an
exemption or a variance has been granted, it is expected
that more stringent monitoring requirements, full
utilization of the public notification provisions and
special notification to physicians and susceptible
individuals, increased health surveillance programs, and the
provision of alternate water supplies for susceptible
individuals, will be conditions to the variance or exemption
as the particular circumstances warrant.
A. Bacteriological
The maximum contaminant levels for coliform bacteria are
one per 100 milliliters as the arithmetic mean of all
samples examined per month, with no more than five percent
of the samples containing more than four coliform bacteria
when the membrane filter technique is used; and when the
fermentation tube technique is used, coliform bacteria may
not be present in more than 10 percent of the portions in
any month for 10 milliliter standard portions, or more than
60 percent for 100 milliliter standard portions.
The Community Water Supply Study of 1969 indicated that
problems could be expected in meeting the coliform
standards. Seventeen percent (17%) of the systems failed to
meet the MCL. Sixty-nine percent (69%) of those failures
were from poorly protected and/or inadequately treated
sources. The presence of coliform organisms is an indica-
tion of the presence of fecal matter in the water and is a
warning that pathogenic bacteria indigenous to the
intestinal environment may also be present. The presence of
any type of coliform organism, fecal or non-fecal, in
treated water suggests either inadequate treatment or
contamination after disinfection, and should not be
tolerated above the MCL. Methods are readily available to
alleviate either of those causes; therefore, no variance or
exemption from the coliform MCLs may be granted .
B. Turbidity
The regulation states that the MCL for turbidity
measured at an entry point into the distribution system is:
(a) one turbidity unit (TU), as determined by a monthly
average, except that five or fewer TU’s may be allowed if
the supplier of water can demonstrate to the Agency with
primary enforcement responsibility that the higher turbidity
does not do any of the following:

(1) interfere with disinfection;
(2) prevent maintenance of an effective
disinfectant agent throughout the distribution system; or,
(3) interfere with microbiological determinations.
(b) five TU’s based on an average for two consecutive
As implied in the National Interim Primary Drinking
Water Regulations there is a relationship between the level
of turbidity and the effectiveness of the disinfection
process. Permitting the turbidity level to exceed the MCL
may present a risk to the health of the persons served by
such a system. It is recognized that the degree of risk is
related to the type and level of turbidity present (as well
as other factors, i.e., water source, disinfection practice,
type of treatment, pH, etc.).
In some cases where an assessment of risk indicates that
elevated turbidity levels can be demonstrated not to
interfere with the disinfection process, and where the other
conditions relating to the higher turbidity are met,
exemptions may be given above 5 TU but the schedule for
compliance should be kept to the shortest time necessary to
correct the situation. Conventional coagulation and
filtration methods are effective in reducing turbidity to
below 1 TU.
C. Inorganic Chemicals
1. Arsenic (0.05 mg/i)
Arsenic is widely distributed at low concentrations in
the waters of the United States. In one study of selected
minor elements in 728 samples of U.S. surface waters, the
concentration of arsenic ranged from less than 10 ug to
1,100 ug/liter. A study by the United States Geological
Survey of river waters revealed that the median
concentration of arsenic was less than the lower limit of
detection, but 22% of the samples had concentrations of
10—20 ug/liter. In this survey, except for local anomalies
where arsenic concentrations could be traced to industrial
sources, no major regional differences could be detected in
average values or in percentage of contaminated samples.

Health Effects
The toxicity of arsenic compounds is extremely variable
and depends on the species exposed, the other contaminants
present, the formulation of the arsenical, the route of
exposure, and the rate and duration of exposure. Although
man is susceptible to arsenic poisoning, there is a wide
variation in susceptibility to specific arsenic compounds.
The lethal oral dose (acute toxicity) of the more toxic
arsenic compounds (trivalent) in most test animal species
appears to be 1—25 mg/kg of body weight (Goodman & Gilman,
1970), whereas the lethal dose for the less toxic compounds
may range from 10—400 times this amount.
There is no acceptable animal model for study of
arsenic-induced cancer. Arsenic causes fetal death at high
doses and malformations at lower exposures in hamsters, mice
and rats. Bacterial systems have revealed that arsenic
interferes with DNA repair (Rossman and Troll, 1978). The
different forms of’ arsenic and its various contaminants
which exist in the environment may account for differences
in clinical manifestations between different localities.
There is some epidemiological evidence from foreign
studies (Chile and Taiwan) that high concentrations of
arsenic in drinking water along with other active contami-
nants may be associated with skin cancer; however, this
effect has not been seen in American populations at high
exposure levels. The NAS stated, “If’ the time factors for
the development of cancer are shown to be reasonable then
the current interim standard of 50 ug/liter may not provide
an adequate margin of safety.”
Several methods by which arsenic can be removed are
coagulation and flocculation through adsorption of the
arsenic on aluminum or ferric hydroxide particles; ion
exchange using activated alumina; and lime coagulation,
recarbonation and filtration.
Since the current MCL may provide only a small margin of
safety, and since arsenic and its contaminants have been
possibly linked to cancer, exemptions only up to 100
ug/liter should be considered. The chronic effects of
arsenic (nerve conduction velocity changes) do not clini-
cally present themselves in the general population over
time. However, the reversible sub—clinical effects may

manifest themselves in susceptible populations. Therefore,
only limited exposure (five years or less) does not present
an imminent health hazard. Compliance schedules should
provide for the early installation of treatment processes
(or for alternate solutions.) Variances would not be
appropriate since treatment is available to control arsenic
to the MCL.
2. Barium (1 mg/l)
Barium occurs naturally in almost all surface waters.
Finished water of public water systems frequently contains
barium, at 1—172 ug/liter, with a mean of 28.6 ug/liter;
94% of the determinations made in the 100 largest U.S.
cities were less than 100 ug/liter. All but two of 2,595
tap water samples were less than the interim standard
(McCabe, 1970). With a tantalum liner insert, the barium
detection limit of the flameless atomic absorption procedure
can be improved from 10 ugh to 0.1 ugh (Renshaw, 1973).
No vital metabolic function has yet been found for
barium, although it is believed to be beneficial for rats
and guinea pigs under specific dietary conditions
(Underwood, 1971).
Barium is highly toxic when soluble salts are ingested.
Fatalities have occurred from mistaken use of a barium salt
rodenticide. The fatal dose of barium chloride for man has
been reported to be about 0.8—0.9 g, or 550—600 mg of barium
(Sollman, 1957).
Industrial exposure to barium oxide and sulfate dusts
produces a benign pneumon000niosis called “baritosis. H
Although barium poisoning is rare in industry, the potential
from the more soluble forms is real. The American
Conference of Governmental Industrial Hygienists set an
airborne threshold limit value (TLV) for barium of 0.5
mg/rn 3 . The limit was based on several years of obser-
vation of workers at Los Alainos exposed to barium nitrate.
Health Effects
Acute barium poisoning exerts a strong, prolonged
stimulant action on all muscles, including cardiac and
smooth muscle of the gastrointestinal tract and bladder.
Barium is capable of causing nerve block (deNo, 1946) and in
small or moderate doses produces a transient increase in
blood pressure by vasoconstrict.ion (Gostev, 1944).

There has been no determination of the chronic effects
of barium administered repeatedly over a long period, either
in food or drinking water. There has been a recent study
(Brenniman, 1979) which suggests the possibility of higher
risk of cardiovascular disease, however, reevaluation of the
data base and methodology employed are underway at the
present time.
The drinking water MCL was derived from the 8—hour
weighted maximum allowable concentration (TLV) in industrial
air of 0.5 mg/rn 3 set by the American Conference of Govern-
mental Industrial Hygienists. It was assumed that, with an
8—hour inhalation of 10 m 3 of air, the daily intake would
be 5 mg of barium, of which 75% would be absorbed in the
bloodstream. It was assumed that 90% transferred across the
gastrointestinal tract after ingestion. Based on the above
assumptions, it was reasoned that a concentration of about 2
mg/liter of water would be safe for adults. To provide
added safety for more susceptible members of the population,
such as children, a level of 1 mg/liter was recommended.
There have been no long—range feeding studies to confirm the
safety of this barium intake.
In one recent preliminary study, groups of young adult
rats of both sexes were exposed to 0, 10, 50, or 250 mg of
barium as barium chloride in drinking water for 14, 8, or 13
weeks. No adverse effects related to barium ingestion were
observed in food consumption, clinical signs, body weight,
hematologic parameters, serum enzyme activities, serum ions,
gross pathology, and histopathology. (Tardiff, et al.,
1978). —
Treatments to control barium concentrations include lime
softening and ion exchange softening; however, it should be
noted that the latter may also increase sodium ion concen-
trations. Increased corrosion of the distribution system
from soft water may also release heavy metals. Since effec-
tive treatments are available, variances should not need to
be granted.
In the absence of more definitive data, exemptions may
be considered for communities whose drinking water have
barium concentrations up to two (2) mg/liter providing that
no adverse health effects attributable to the drinking water

I II— 7
are discernible. The level of 2 mg/i barium in drinking
water was calculated from the data (Reference Man) suggest-
ing that adsorption of barium from the gastrointestinal
tract in children is approximately 25% of ingested amounts.
Therefore, a 10 kg child drinking 1 liter of water contain-
ing 14 mg/l barium may absorb 1 ing of barium. Incorporation
of an additional safety factor for high risk individuals
reduces the recommendations to 2 mg/i.
The conditions for granting an exemption should include
measures taken to minimize barium levels as soon as
feasible. These may include source selection, control of
sources if possible, and installation of treatment. Public
water systems whose barium concentration levels exceed 2
mg/i should develop a plan to survey and sample the high
risk residents to monitor for blood pressure and CVD factors
for that community versus non—high Barium communities. This
monitoring should continue throughout the exemption period.
The survey should also include a questionnaire which gathers
information about the use of home water softening devices,
including type of device and length of use.
Public water systems whose barium concentration levels
exceed the MCL should monitor the water supply at least
quarterly for levels of barium and sodium (because of
softening) at the tap. Physicians should also be notified
using the licensure registry. Normal public notification is
also required.
The above survey data which provide a baseline for
epidemiological investigations should be used by State
health officials to determine if any observed health effect
is relatable to water quality. Any finding of an adverse
health effect attributable to elevated barium concentrations
provides grounds for reconsideration or revocation of the
3. Cadmium (0.010 mg/i)
Cadmium is not known to be an essential or beneficial
element. It has been found in 2—3% of U.S. surface waters,
generally in concentrations not exceeding a few micrograms
per liter because solubilities of cadmium carbonate and
hydroxide are low at pH greater than 6. Only 0.1% of the
supplies in the Community Water Supply Survey showed cadmium
in excess of 10 ug/liter. In addition to its geological
sources, cadmium enters water from the discharge of plating
wastes and by corrosion of plumbing by soft aggressive
water. Using the graphite furnace to atomize samples, the
limit of detection iS 0.005 ug/liter (Paris, 1971).

Food is the primary source of cadmium intake (Drinking
Water and Health, 1977). Total daily intake from air,
water, food and tobacco ranges from 110 ug/day for the rural
nonsmoker on a low cadmium diet to 190 ug/day for the urban
smoker on a high cadmium diet. Cigarette tobacco contains
cadmium at about 1 ppm. Friberg (197k) has estimated that
smoking one pack of cigarettes per day contributes 2—k ug of
cadmium per day. Drinking water contributes only a small
fraction (< 5%) to this total intake.
Health Effects
Chronic ingestion of cadmium levels greater than 100
ug/day, in combination with several other necessary
predisposing factors, was found to be responsible for the
onset of “Itai—Itai” disease in Japan (Friberg, et al.
1972). Dietary intakes of amounts in excess of a milligram
per day are needed for appearance of acute toxicity. Major
toxic effects are on the kidney (Friberg, et al. 192k;
Nordberg, 1976); data indicate that the toxicity of cadmium
is related to the zinc: calcium ratio within the organs.
Therefore, zinc and calcium may be protective against
cadmium intoxication. Persons deficient in these elements,
and especially lactose—intolerant persons, (from school age
and up) who are also likely to be calcium—deficient, may
constitute a high-risk group relative to cadmium. Animal
studies have shown cadmium to be possibly teratogenic in the
rat at high doses (2—13 mg/kg). Cadmium has also been
implicated as a factor in hypertension. (Schroeder, 1965).
The renal cortex is considered to be the critical organ
for accumulation of cadmium from low level dietary expo-
sures, and the critical concentration for the renal cortex
is approximately 200 ug/g of tissue net weight (Friberg, et
al. 19711; Norberg, 1976). At greater concentrations,
irreversible renal injury may occur (Drinking Water and
Health, 1977).
Treatment methods for reduction of levels of soluble
forms of cadmium (chlorides, nitrates and sulfates) include
lime softening and ferric sulfate coagulation at high pH.
Coagulation and sedimentation is effective for removal of
insoluble forms (carbonates and hydroxides). When the
source of cadmium is corrosion of galvanized or plated
plumbing pipe and fixtures, reduction of concentration can
best be effected by pH adjustment or other corrosion control

Insufficient data are available for establishment of a
suggested no adverse reaction level. However, consumption
of two liters/day of water containing 10 ug/liter of cadmium
would contribute about 20% of the normal total daily adult
intake, which is 2.5 times more than smoking two packs of’
cigarettes daily. This level of ingestion (to the daily
intake) was considered in the setting of’ the MCL.
The toxic effects of cadmium and the economic factors
relating to available treatment methods for the soluble
forms of cadmium lead to the conclusion that exemptions
should be considered for levels up to 0.02 mg/i only and for
minimum time periods necessary to blend or stabilize waters
to bring the levels down to the MCL of 0.01 mg/i or to
institute necessary treatment processes.
14• Chromium (0.05 mg/i)
Occur r en cc
Durum and Haffty (1961) reported a range of concentra-
tions for chromium in U.S. rivers of 0.7—8k ug/liter. Kopp
and Kroner (1967) detected chromium in 2 .5% of the samples
examined, with concentrations ranging from 1—112 ug/liter
and averaging 9.7 ug/liter. In a study of surface and
groundwater in Canada, all but two of 2 0 samples examined
were below 50 ug/liter. In 197 4, a maximum dissolved
chromium concentration of’ 31 0 ug/liter was recorded in water
from the Pecos River, New Mexico; the Los Angeles River; and
the Columbia River, Oregon (USGS, 19714). In a 1970 survey,
11 of 700 samples had chromium concentrations of’ 6—50
ug/liter, with none exceeding 50 ug/liter. Ackermann (1971)
reported chromium concentrations below 5 ug/liter for 18 of’
27 river stations in Illinois; the maximum was 50 ug/liter.
Health Effects
Although hexavalent chromium has long been recognized as
a toxic substance, trivalent chromium is considered by most
investigators to be relatively innocuous and even (in
microgram amounts) essential to human health. The chronic
adverse effects most often considered in chromium toxicity
are respiratory and dermatologic.

With regard to carcinogenicity, intraosseous,
intra—muscular, subcutaneous, intrapleural, and intraperi—
tonel injections of chromium compounds have been reported to
cause the development of sarcomas in rabbits, mice and rats.
There is some evidence that chromium chloride in the form of
a pellet attached to the bronchial mucosa in the rat lung
may be carcinogenic, but there is no support for the view
that it constitutes a carcinogenic hazard in human food
(Sunderman, 1971). An IARC working group (1973) concluded
“there is no evidence that non—occupational exposure to
chromium constitutes a cancer hazard.”
Methods for treatment of total and hexavalent chromium
are pH adjustment followed by ferrous sulfate coagulation.
The insoluble forms of chromium can be removed by
conventional sedimentation and coagulation processes.
Trivalent chromium can be removed by lime softening and
coagulation with alum or iron.
Chromium compounds are quite often found as corrosion
control inhibitors in cooling waters and there is a
possibility of contamination through cross—connections. In
such cases of contamination, obviously correction of the
cross—connection is the appropriate remedial action.
It is recommended that exemptions for trivalent chromium
up to 0.5 mg/i, and 0.1 for hexavalent chromium, may be
given for short time periods necessary to provide adequate
treatment (or alternate solutions) to reduce the chromium
level to or below the 0.05 mg/i MCL.
5. Fluoride (1.14_2.14 mg/i dependent on temperature)
In 1969 the Community Water Supply Survey of the Public
Health Service sampled 969 water supplies and found fluoride
ranging from less than 0.2 up to 14.110 mg/liter. Fifty—two
systems had fluoride concentrations greater than the then
recommended limits for this constituent.
A more extensive survey in the same year by the Dental
Health Division of the Public Health Service (1970) showed
that 8.1 million people in 2,630 communities in 114 states

were consuming water with more than 0.7 mg/liter of
naturally occurring fluoride. Nearly one million people in
521 communities were receiving water with more than 2
mg/liter of naturally occurring fluoride.
Most of the communities with more than 0.7 mg/liter
natural fluoride were in Arizona, Colorado, Illinois, Iowa,
New Mexico, Ohio, Oklahoma, South Dakota and Texas. There
were no reports of community water supplies with as much as
0.7 mg/liter fluoride from Delaware, Hawaii, Massachusetts,
Pennsylvania, Tennessee or Vermont.
Health Effects
The physiological response to elevated fluoride levels
is the occurrence of various degrees of fluorosis, or dental
mottling, affecting teeth during their formative stages.
Further manifestations of physiological harm can occur from
ingestion of high levels of fluoride, but no water supplies
in this country are known to have sufficiently high fluoride
levels to cause other than dental mottling. At levels up to
8 mg/i (and possibly higher) there have been no other known
harmful effects on adults drinking such water. The severity
of mottling (affecting children only) and the number of
children affected can be assumed to be in proportion to the
extent the maximum contaminant level is exceeded.
Sufficient variations from this proportion exist to warrant
using some other means for determining that there is no
unreasonable risk to health. The affected supply should
obtain some epidemiological data to substantiate the claim
of no adverse health risk.
Conventional procedures of water treatment, i.e.
clarification, filtration, softening, disinfection, have
little or no effect on the fluoride concentration in water.
However, it was noted in Ohio in the 1930’s that if the pH
were increased during softening operations to a value high
enough to precipitate magnesium hydroxide, some removal of
fluoride was accomplished (Scott, et al., 1937). In most
full—scale plants the removal of fluoride was less than 50
percent. Two processes have been used for fluoride removal,
both based on the adsorption of fluoride on granular media,
either activated alumina or bone char (Maier, 1963). The
water containing fluoride is passed through a bed of the
medium until the effluent concentration exceeds an
acceptable value. The medium is then regenerated with a
solution of sodium hydroxide to remove adsorbed fluoride.

Exemptions should be based upon the risk to health from
the occurrence of water—related moderate—to—severe fluoro—
313, (e.g., “Dean’s Community” index exceeding 1.5) and the
availability of higher quality water via treatment or blend-
ing with other sources. While additional studies are being
conducted by EPA and the National Institute for Dental
Research, exemptions should be readily available up to about
four times the optimal, providing it can be shown that
water—related excess moderate—to—severe fluorosis is not
evident. In questionable cases or where higher fluoride
concentrations are encountered, exemptions and compliance
schedules should be determined by the State primarily from
well—designed epidemiological studies involving children who
have resided in the community of interest for an extended
period of time.
6. Lead (0.05 mg/l)
A survey of the mineral content of finished water in the
100 largest cities in the United States was made in 1962
(Shapiro). For lead, the following values were found:
maximum, 62 ug/liter; median, 3.7 ug/liter; minimum, not
detectable. In another study of raw and finished water in
the United States, covering the period 1962—1967, Knopp
(1973) reported the following data for finished water:
frequency of detection, 18.1%; minimum, 1 ug/liter (minimum
detectable source); maximum, 139 ug/liter; mean, 33.9
ug/liter. The corresponding values for raw water were as
follows: frequency of detection, 19.32%; minimum, 2
ug/liter; maximum, 1 0 ug/liter; mean, 23 ug/liter. The
increment in the mean value for finished water suggests that
lead was picked up from plumbing systems.
Water samples collected at the tap serviced by 969 water
systems throughout the United States indicated an average
lead concentration of 13.1 ug/liter (Mccabe, 1970). Of the
2,595 samples, 1. 4% contained levels higher than the MCL of
50 ug/liter, with a maximum of 6’ ug/liter.
Available data generally indicates that the addition of
lead to drinking water occurs chiefly in the distribution
system, including household plumbing, and this is most
likely to occur with soft “aggressive” water.

Important local variations occur, apparently in relation
to the use of soft “aggressive” water of slightly acidic pH
and the use of lead pipe in service and domestic water
lines. Craun and McCabe (1975) have used data from Seattle
and Boston to illustrate the effect of “corrosive” water of
slightly acidic pH on lead concentrations in finished drink-
ing water. Karalekas et. al., (1975) have made further
studies in the metropolitan Boston area by collecting multi-
ple water samples from 383 households in Boston, Cambridge,
and Somerville, Massachusetts. These cities were selected
for study mainly because of the wide use of lead pipe in
service lines. Lead concentrations at the tap ranged from
13 to 1,150 ug/liter, with a mean of 30 ug/liter. In all
cases, the lead content of drinking water was higher at the
tap than at the treatment plant. Highest concentrations
were found in early morning samples, with the lowest mean
concentrations in running water and intermediate values in
standing water and in composite samples obtained throughout
the day. Very substantial reductions have been obtained by
raising the pH of the water to approximately 8. Various
lead salts are not highly soluble in water (the carbonate
and hydroxide are insoluble and the sulfate is slightly
soluble). Natural waters in limestone galena areas can have
lead levels ranging from 0.14_0.8 mg/l, although fortunately,
these areas are rare. Contamination usually occurs from
industrial and mining effluents and from the use of lead and
galvanized water piping.
Health Effects
If one uses the critical toxic effect approach to
preventive medicine (Nordberg, 1976), then a water lead
content of’ 100 ug/liter at the household tap is not
acceptable. The NAS data suggested that the present limit of
50 ug/liter may not, in view of other sources of
environmental exposure, provide a sufficient margin of
safety, particularly for fetuses and young growing children.
The physiological response to lead is both acute and
chronic, and varies from gastrointestinal disturbances to
encephalopathy, depending on total accumulation of lead in
the body.
Elevated lead levels from piping systems and aggressive
water can be controlled by pH and alkalinity control and
stabilization or pipe replacement. Where high concentration
is due to contamination of natural waters, conventional
treatment methods (settling, alum and ferric chloride
coagulation, and lime softening) are extremely effective.

111—1 14
Because of the very small margin of safety, and because
lead levels can usually be readily controlled, no variances
should be granted for lead in drinking water and exemptions
only where no other course is possible. Steps must be taken
immediately to achieve compliance and provide alternate
drinking water for young children and pregnant women.
7. Mercury (0.002 mg/l)
The Department of Interior carried out a nationwide
reconnaissance of mercury in U.S. water in the summer and
fall of 1970 (Jenne et al., 1972). Of the samples from the
industrial wastewater category, 30% contained mercury at
greater than 10 ug/liter; nearly 0.5% of the samples in this
group contained more than 1,000 ug/liter. Only 14% of the
surface—water samples contained in excess of 10 ug/liter.
The higher mercury concentrations were generally found in
small streams. About half the 143 samples from the
Mississippi River contained less than 0.1 ug/liter. The
mercury content of lakes and reservoirs was between 0.1 and
1.8 ug/liter. With few exceptions, the mercury content of
groundwater samples was below detection.
In a survey done by the EPA Division of Water Hygiene,
273 community, recreational and Federal installation water
supplies were examined. Of these 261 or 95.5% showed either
no detectable mercury or less than 1.0 ug/liter in the raw
and finished water. Eleven of the supplies had mercury
concentrations of 1.0—14.8 ug/liter.
The current problems concerning mercury contamination of
the environment appear to be related mainly to rnethylmercury
compounds. The presence of these compounds in foods
(principally in fish) and the accidental ingestion of
treated seed grain or the ingestion of meat from animals
that had been fed grain treated with alkylmercury compounds
are the major concern. Limitations are imposed or are being
imposed by responsible agencies on the industrial discharge
of mercury containing wastes that contribute to methylmer-
cury contamination of fish, on the allowable mercury content
in fish used for human consumption, and on the use of
mercurial fungicides, and these actions should minimize the
mercury hazard to man from these sources.

Health Effects
Exposure to metallic mercury via routes other than
inhalation is infrequent. However, metallic mercury (or
mercury salts) can be converted by bacterial action into
organic mercury óompounds, notably methylmeroury.
Methylmercury and other short—chain alkylmercury
compounds exert their main toxicologic effects on the
nervous system. The factors that determine the biotrans-
formation of mercurials, their passage through barriers in
the body, and the ultimate action on cellular mechanisms are
only beginning to be understood. Chronic alkyl mercury
poisoning, also known as Minimata Disease, is an insidious
form of mercurialism whose onset may appear after only a few
weeks of exposure or may not appear until after a few years
of exposure. Poisoning is characterized mainly by major
neurological symptoms and leads to permanent damage or
death. The clinical features in children and adults include
numbness and tingling of the extremities, incoordination,
loss of vision and hearing, and intellectual deterioration.
Autopsy of the clinical cases reveals severe brain damage
throughout the cortex and cerebellum. There is evidence to
suggest that compensatory mechanisms of the nervous system
can delay recognition of the disease even when partial brain
damage exists. From epidemiological evidence, the lowest
whole—blood concentration of rnethylmercury associated with
toxic symptoms is 0.2 ug/g. This value corresponds to
prolonged, continuous exposure at approximately 0.3 mg Hg/70
kg/day. Applying a safety factor of 10 to this value
results in an “acceptable daily intake” of 0.03 mg of
mercury, or about 0. ug/kg of body weight. It should be
noted that the major source of mercury in the diet is fish,
and that the ADI can readily be attained by the consumption
of a moderate quantity fish with the FDA—permitted concen-
tration of mercury.
Inorganic mercury can be removed by iron and alum
coagulation, and lime softening is also moderately
effective. Granular activated carbon and ion exchange show
promise for inorganic mercury removal. Organic mercury,
while more difficult to remove, can be treated with powdered
or granular activated carbon.

It is recommended that no variance be granted for
mercury as conventional treatment methods are adequate to
reach the MCL or below. Exemptions for inorganic mercury
can be issued in order that appropriate treatment facilities
can be placed into operation and the time schedule should be
kept to a minimum. No exemptions should be issued for
organic mercury contamination.
8. Nitrate (10 mg/i as N)
Major point sources of combined nitrogen are municipal
and industrial wastewaters, refuse dumps, animal feed lots
and septic tanks. Diffuse sources include runoff or
leachate from manured or fertilized agricultural lands,
urban drainage and biochemical nitrification. A few tenths
of a milligram per liter of combined nitrogen occurs in
rainfall from solution of atmospheric ammonia and oxides of
In the Community Water Supply Survey of 1969, the range
of nitrate concentrations found was 0.0—127 mg/liter.
Nineteen systems, about 3% of those examined for nitrate,
had concentrations in excess of the then recommended limit
of 1 5 mg/i. Ground waters from shallow wells often have high
concentrations of nitrate. Statewide records in Illinois
show high nitrate to be more common in wells less than 50
feet deep (Larson and Henley, 1966).
Analyses of over 5,000 waters in Missouri showed that 27
percent of the waters contained nitrate—nitrogen in excess
of 10 mg/liter (Smith, 1970). Forty—five percent of 250
wells in Wisconsin that were examined twice monthly for more
than a year, consistently yielded water containing more than
10 mg/liter nitrate—nitrogen and 71 percent of the well
waters exceeded this level at least once. (Crabtree, 1970).
In Nassau County, New York, 370 wells supply 1.5 million
people. In 1969, water from twenty of these wells showed
more than 10 mg/liter nitrate-nitrogen (Smith and Baier,
1969). In Southern California, certain public water
supplies have exceeded 10 mg/liter nitrate—nitrogen since
Health Effects
Nitrate may be converted to nitrite. Nitrite is
directly toxic by reaction with hemoglobin to form
methemoglobin and causes methemoglobinemia. It also reacts

readily under appropriate conditions with secondary amines
and similar nitrogenous compounds to form N-nitroso
compounds which are potent carcinogens. Epidemiological
evidence on the occurrence of methemoglobinemia in infants
tends to confirm a value near 10 mg/liter nitrate (as
nitrogen) as a maximum contaminant level for water with no
observed adverse health effects, but there is little margin
of safety in this value. The occurrence data on
methemoglobinemia show that incidence rate increases as
nitrate concentration increases, but that below about 20
mg/liter nitrate as nitrogen the incidence rate remains low.
Only one case of methemoglobinemia has been solely
attributed to public water supplies. (APHA, 1950; NAS,
The highly sporadic incidence of methemoglobinemia when
drinking water contains greater concentrations of nitrate
suggests that factors other than nitrate intake are
important in connection with development of the disease.
These factors include intestinal bacteria, dietary intake,
bacterial contamination of the water, etc.
Each link in the chain of reactions from nitrate to N—
nitroso compound(s) has been shown to occur in some situa-
tions in man or other animals. The extent of operation of
the overall reaction chain in humans has not been shown, and
the mechanism by which other environmental or internal
factors affect potential formation of N—nitroso compounds is
not known.
Surveys indicate that water containing less than 10 mg/l
nitrate—nitrogen has not caused methemoglobinemia, while
serious and occasionally fatal poisonings in infants have
occurred in some cases when water concentration exceeded 10
mg/i. In no case should waters with nitrate—nitrogen
concentrations greater than 10 mg/l be used for feeding
infants below 6 months of’ age. There is very little safety
factor inherent in the 10 mg/l limit for infants. Where the
limit is exceeded and while alternative sources are being
sought or treatment facilities are being installed,
extremely diligent efforts should be made to assure that the
water is not used for infant feeding.
It must be remembered that consumption of water with a
high (greater than 10 mg/l) concentration of nitrate-
nitrogen for a period as short as a day may result in the
occurrence of methemoglobinemia.

An ion exchange process specifically designed for
nitrate removal has been developed. However, since the
presence of nitrate in ground waters is frequently the
result of contamination from the surface, protection of the
water source by proper well construction or modification can
often effectively eliminate nitrate from these waters.
Exemptions may be granted up to 20 mg/i N0 3 —nitrogen
so long as nitrite is not present at levels approaching 1
mg/l nitrite—nitrogen. Ip every case where an exemption
from the MCL is granted the following actions should be
taken immediately:
1. Public notice should be given through available media
(newspapers, radio, television, etc.) that water from the
public water system is not to be used in preparing infant
formula until corrections have been made or the MCL is no
longer exceeded.
2. Physicians should be notified utilizing the licensure
register and requested to advise their patients with infant
children (up to 6 months) of the potential problem.
3. Special efforts should be made to notify the
transient population of the existing situation (e.g.,
through placarding).
1t. Conveniently placed, low nitrate water should be
provided for the high risk population.
5. The local health department, visiting nurses
association, and pediatrics departments of hospitals should
be informed so they can take the necessary precautions and
properly advise parents of infant children.
6. Notification given in 2. and 3. above should be
repeated at 3—month intervals until the nitrate concentra-
tions meet the MCL.
Provision of bottled water having satisfactory nitrate
content is also recommended for the high risk group during
the exemption period.

9. Selenium (0.01 mg/i)
An extensive study by the Department of Health, Education
and Welfare involving analyses of 535 samples of water from
major U.S. watersheds indicated that only two isolated
samples contained selenium at more than 10 ug/liter of water
(Lakin and Davidson, 1967). In another study, over a two
year period, it was reported that there was a maximum of 10
and a mean of 8 ug/liter in the finished water of 19 4 public
water supplies (Taylor, 1963). In a study in Oregon, the
majority of farm samples of water had less than 1 ug/liter
(Hadjimarkos and Bonhorst, 1961).
River water may contain high concentrations of selenium
where irrigation drainage from seleniferous soils empties
into it. Values of 2,000 ug/liter have been reported
(Williams and Byers, 1935). Waters from some springs and
shallow wells contain selenium at more than 100 ug/liter
(Eyers, 1938; Miller and Byers, 1935; Morette and Diven,
1965), but, deep wells may contain only a few micrograms per
liter. Waters from some Wyoming wells contain enough
selenium to be poisonous to man and livestock (Beath, 1962).
In another report from Wyoming, a high concentration of
selenate in well water on an Indian reservation was
associated with the loss of hair and nails in children
(Beath, 1962).
Health Effects
Available reports indicate little danger of toxicity
from amounts of selenium found in finished waters, but wells
drilled through seleniferous shale containing soluble
selenium may have concentrations of selenium high enough to
be of concern.
The determination of a “suggested no—adverse reaction
level” for selenium is complicated by numerous experimental
variables. The toxic effect of selenium depends on the type
of selenium compound encountered, whether it is organic or
inorganic, the valence state of the selenium ion, the
species and sex of the laboratory animal used, the age of
the animal, the conditions and duration of the test, and the
diet——whether natural or semipurified ingredients, the
protein content, the caloric intake, the type of protein,
and the presence and concentrations of other elements, such
as arsenic, mercury, thallium, and fluorine. Total exposure
is the significant factor; human exposure from food and air
may be elevated in those areas with high natural selenium
levels in the drinking water.

The National Academy of Sciences (Committee on
Nutritional Misinformation, 1976) reported 2 00—3OOO ug
selenium as the daily dose for overt selenium intoxication
in humans after long-term exposure. On applying a safety
factor of 10 for sensitive populations, the acceptable daily
intake dose has been calculated as 2k0—300 ug of selenium.
Since, selenium exposure from the diet in areas with high
natural selenium levels is approximately 200 ug/day or 200
ug daily, total exposure from drinking water should not
exceed more than approximately 140 1OO ug selenium daily in
those areas.
The literature indicates that selenium is found as an
anion in aqueous solutions as either Se0 3 2 (selenite)
or SeO 2 (selenate). Laboratory experiments and pilot
studies have shown that alum and ferric sulfates coagulation
and iiq e softening are moderately effective for the removal
of e ’ (selenite) from water. Although the studies on
Se ° (selenate) are preliminary, they indicate that
selenate can be removed by use of ion exchange and reverse
In granting variances and/or exemptions, it is important
to know the valence form in order to determine the feasibil-
ity and cost of removal. Assuming consumption of 2 liters
of water daily per adult, exemptions for selenium in
drinking water may be granted up to 20 ug — 50 ug per liter.
10. Silver (0.05 mg/i)
Silver should present no problem in water. It is not
found as a natural constituent of drinking waters. The need
for a standard arises from the intentional addition of the
element to water as a disinfectant.
Health Effects
The limit of 50 ug/liter is based on the possible
occurrence of argyria, a blue—gray discoloration of the
skin, eyes and mucous membranes, resulting from the
introduction of one gram of silver into the body. Assuming
that all silver ingested is deposited in the skin, it is
calculated that 50 ugh silver could be ingested for
approximately 27 years before 1 gram of silver would be

111—2 1
It is recommended that no variance or exemptions should
be given.
D. Organic Compounds
2, 1 t—D 0.1 mg/i
2,k,5 TP Siivex 0.01 mg/i
Chlorinated Hydrocarbons
Endrin 0.0002 mg/i
Lindane 0.O0 mg/i
Methoxychior 0.1 mg/i
Toxaphene 0.005 mg/i
1. 2, 1 4—D (0.1 mg/i)
2, 1 1—D is found in water (Manigold and Schuize, 1969).
Concentrations as high as 70 ppb have been detected in
Oregon streams after aerial application to forest land
(Hiatt, 1976). 2,4—D was detected in raw water at 0.05
ug/liter, in Lafayette, Indiana (USEPA, 1975j). The NAS has
reported 2, 1 4—D up to O.0 ug/l in water (! 2 FR 132135776,
1977). Few surveys have found 2, —D in finished water;
therefore, no average or median is reported. An ongoing
organics survey may have these figures within the year.
Health Effects
The acute toxicity of 2,L _D in man includes fibriliary
twitching and muscular paralysis. Serum glutamie oxalacetic
transaininase, glutamic pyruvic transaininase, lactic de—
hydrogenase, aldolase and creatine phosphate were increased,
and both hemoglobinuria and myoglobinuria were observed. A
1—month loss of sexual potency was reported (Berwick, 1970).
After a 23—year old man used 2, —D in suicide, the
lethal dose was estimated to be over 90 mg/kg (Nielson,
Assouly (1951) is reported to have taken 2, —D daily at
8 mg/kg for 3 weeks without harmful effects. Data from Dow
Chemical Co. (Johnson, 1971) on 220 workers exposed to 2, 1 -D
at O. 3—O.57 mg/kg per day over a period of 0.5—22 years
showed no significant differences from data on an unexposed
human population.

The acute toxicity of 2,k—D is moderate in a number of
animal species with LD 50 values of 100_5111 mg/kg for rats,
mice, guinea pigs, chicks, and dogs (Drill and Hiratzka,
1953; Rowe and Hymas, 19514). Salts and esters of 2, 1 4—D show
an even lower degree of acute toxicity.
The subchronjc and chronic effects are outlined below:
Young adult female rats were given oral doses of 2, 1 4-D
in olive oil at 0, 3, 10, 30, 100 and 300 mg/kg five times a
week for 14 weeks (Rowe and Hymas, 19514). No adverse effects
were noted at 30 mg/kg and below but depressed growth rates,
liver pathology, and gastrointestinal irritation occurred at
300 mg/kg. In another experiment (Rowe and Hymas, 19514),
depressed growth, liver pathology, mortalities and increased
liver/body weight ratios were observed in rats fed 1,000 ppm
2,k—D for 113 days.
2, 1 1—D was administered orally to dogs at dosage levels
of 0, 2, 5, 10, and 20 mg/kg five days a week for 13 weeks
(Drill and Hiratzka, 1953). Three of four animals receiving
20 mg/kg dose died within 149 days. These animals showed a
definite decrease in the percentage of lympocytes in the
peripheral blood. The surviving animals in all groups did
not show any hematological abnormalities.
Dietary levels of 0, 5, 25, 125, 625 and 1,250 ppm
technical grade 2,4—D were fed to female and male
Osborn—Mendel rats for two years (Hansen et al., 1971). No
significant effects were observed on growth, survival rate,
organ weights, or hematologic parameters. There was also no
elevated incidence of tumors over that seen in controls.
In a parallel study (Hansen et al., 1971), groups of 6—8
month old beagle dogs received 0, i 7 50, 100 and 500 ppm of
technical 2,14—D for 2 years. No 2, 1 4—D related effects were
noted. None of the lesions observed in the 30 dogs were
believed related to the treatment. The no—adverse effect
level of 2, 1 4—D in the dog has been established at 8.0
mg/kg/day (Lehman, 1965).
Studies on 2,k—D showed that there was no significant
increase in the incidence of tumors in various mouse strains
initially given 2, 1 4—D or its esters at 146.14 mg/kg/day orally
on days 7—28 post—natally to dams followed by dietary
feeding up to 323 ppm for 18 months (USEPA, 197 1 4b). In
another study, mice that received 2,14—D orally for their
life span showed no increased incidence of tumor formation.
(Vettorazzi, 1975b).

A study (Arkhipor and Kozlova, 197k) reported that two
rats developed fibroadenoma and one hemangioma 27-3 1 months
after receiving one—tenth the LD 50 of the amine salt
orally. Subacute injections in mice produced no tumors
after 33 months.
In a three—generation, six—litter, Osborne—Mendel rat
reproduction study, no deleterious effects due to technical
2, 1 4—D at dietary doses of 100 or 500 ppm were observed
(Hansen et al., 1971). At 1,500 ppm, however, 2, 1 —D,
although affecting neither fertility of either sex nor lit-
ter size, sharply reduced the percentage of pups and the
weights of the weanlings that survived to weaning.
Bage et al. (1973) observed teratogenic and embryotoxic
effects in NMRI mice that received 50 or 110 mg/kg
injections of 2, 1 4—D on days 6—1 4 of gestation. Pregnant
rats were treated orally with 2,k—D at 12.5, 25, 50, 75, and
87.5 mg/kg/day (maximal tolerated dose) or equimolar doses
of propylene glycol butyl ether ester of 2, 1 —D up to 1 2
mg/kg/day or isooctyl ester of 2,4—D up to 131 mg/kg/day on
days 6—15 of gestation (Schwetz et al. 1971). Fetotoxic
responses were seen at high dosages, but teratogenic effects
were not seen at any dosage tested. The authors suggested
that the no—adverse effect dosage of 2, 1 4-D (or the molar
equivalent, in the case of the esters) was 25 mg/kg/day.
Prenatal studies on 2, 1 4—D in Wistar rats showed that it
induced fetotoxic effects and an increased incidence of
skeletal anomalies after single oral doses of 100—150
mg/kg/day on days 6-15 of gestation (Khera and McKinley,
1972). At the highest dosage of 150 mg/kg/day, the isooctyl
ester, and butyl ester, and butoxyethanol and dimethylamine
salts of 2,k—D were all associated with significantly
increased teratologic incidence. The butyl and isooctyl
esters also tended to decrease fetal weight. At a lower
dosage, 2,4—D and its salts and esters induced no apparent
harmful effects.
Pregnant hamsters received technical 2,k—D (three
samples) at 20, 0, 60, and 100 mg/kg/day orally on days
6—10 of gestation (Collins and Williams, 1971). Fetal
anomalies were produced occasionally with 2, 4—D, and the
fetal viability per liter decreased; but neither effect was
clearly dose—related. The lowest dose causing fetal
anomalies with the three technical 2, 1 —D samples was 60

III 21
The NAS concluded that the acute toxicity of 2, 1 1—D is
moderate. No adverse effect doses for 2, 1 —D were up to 62.5
mg/kg/day and 10 mg/kg/day in rats and dogs respectively.
Based on these data, the NAS derived an ADI which was
calculated at 0.0125 mg/kg/day. The available data on
subchronic and chronic toxicity and calculations of ADI are
summarized in Table 111—1.
There are substantial disagreements among various
investigators concerning the results of subchronic and
chronic toxicity studies with 2,4—D, perhaps reflecting the
use of different formulations or preparations.
Activated carbon was effective in reducing 2, 4—D to
below the MCL (Whitehouse, 1967) (Whitehouse, J. D., A Study
of the Removal of Pesticides from Water, University of
Kentucky, Water Resources Institute, Research Report No. 8,
Lexington, Kentucky, 1967).
The present drinking water MCL (0.1 mg/i) for 2,k—D is
in agreement with the above recommendations of the NAS.
Computation of an acceptable level for 2, 1 4—D in drinking
water from the NAS recommendations would result in 0.125
mg/i 2, 1 4—D in drinking water, if one assumes 10 kg body
weight for an average child consuming I liter per day for
chronic exposure. Therefore, the present drinking water MCL
for 2, 1 —D, 0.1 mg/i, is below the level as calculated above
from the NAS recommendations and provides an extra margin of
safety. Exemptions up to 0.2 mg/i may be granted. The
sources of the contaminants should be controlled.
2. 2, 1 ,5—TP (0.01 mg/i)
Health Effects
The acute toxicity of 2, 4,5—TP in animal species other
than man is summarized below:
The oral LD 50 of 2,4,5—TP is reported to be 650 mg/kg
and 500 mg/kg in rats (Toxic Substances List, 197k: Rowe and
Hymas, 195k) and 850 mg/kg in guinea pigs. In rats and
rabbits, the oral LD 50 of the mixed butyl esters and
propylene glycol esters ranged between 500 and 1,000 mg/kg
(Rowe and Hymas, 195k).

The oral LD 50 of 2,4,5—TP is 1410 mg/kg in rats, and
560 mg/kg in mice (Toxic Substances List, 1974: Vershuren et
al., 1975), 550 mg/kg in female guinea pigs, 813 mg/kg in
female rabbits and 940 mg/kg in female chickens. LD 50
values in the rat and mouse by intraperitoneal administra-
tion are 1400 and 500 mg/kg, respectively.
The subchronjc and chronic effects are summarized below:
The propylene glycol butyl ether ester of Silvex (Kuron)
was fed to male and female rats in the diet at 10, 30, 100,
300, and 600 mg/kg/day for 90 days (Mullison, 1966; USEPA,
1975k). Mortalities were observed at 600 mg/kg/day, growth
decrease at 300 and 600 mg/kg/day, and increased liver
weight at 30 mg/kg/day and above. No toxic effect was found
in animals receiving 10 mg/kg/day.
In another 90—day study (Mullison, 1966; USEPA, 1975k),
male and female rats received the sodium salt of 2, 4,5—TP in
the diet at 100, 300, 1,000, 3,000, and 10,000 ppm. Growth
was decreased at 300 ppm (277 ppm 2,14,5—TP equivalent) and
above, and liver weight was increased at 100 ppm (2, 1 4,5—TP
equivalent, 92 ppm). Histopathologic examination showed
liver and kidney damage at all dietary concentrations,
except that the kidneys of females were not affected at 100
Beagles were fed Kurosol SI (a formulation containing
the potassium salt of 2,4,5—TP at 60%, or the equivalent of
2,4—TP at 53%) of 100, 300, and 1,000 ppm for 89 days
(Mullison, 1966; USEPA, 1975k). No adverse effects were
noted at 100 ppm or 300 ppm (2,4,5—TP equivalents 53 or 160
ppm), but a growth rate decrease occurred at 1,000 ppm in
Male and female rats were fed Kurosol SI at 10, 30, 100
and 300 ppm for 2 years (Mullison, 1966; USEPA, 1975k).
Increased kidney weight was seen in males that received 300
ppm, but there were no-adverse effects at 10, 30, and 100
ppm. The no—adverse effect concentration was considered to
be 100 ppm (2,14,5—TP equivalent, 53 ppm) (Mullison, 1966).
The same formulation was fed to beagles at 56, 190 and 560
ppm for 2 years (Mullison, 1966; USEPA, 1975k). Dogs fed
560 ppm showed severe liver pathology after 1 year. At 190
ppm, liver pathology was seen in females sacrificed after 1
year, but not in animals sacrificed at 2 years; in males, no
liver pathology was seen at 1 year, but it was present at 2
years. The no—adverse effect content thus was 56 ppm
(2,14,5—TP equivalent, 30 ppm) for males and 190 ppm

(2,k,5—TP equivalent, 101 ppm) for females (Mullison, 1966).
Another report cited 5 mg/kg/day as the no—adverse-effect
dosage for 2, 1 ,5—TP in rats and dogs in 2—year feeding
studies (Johnson, 1971).
The potential for carcinogenicity was tested in young
male and female mice of the (C57BL/6 x C3H/Anf)F and the
(C5TBL/6 x AKR)F strains. The mice received 2, ,5—TP orally
at mg/kg/day on days 7—28 and thereafter were placed on
a diet containing 2, ,5—TP at 121 ppm for approximately 18
months (Innes et al., 1969). There was no increase in the
incidence of tumors above control values for either strain.
Rats were tested for teratogenicity and overt toxicity,
at doses of 35 mg/kg or below (USEPA, 1975k). No adverse
effects were observed.
In the two year feeding studies the no—adverse-effect
doses for 2, 1 ,5—TP were 5 mg/kg/day and 6.8 mg/kg/day in
dogs and rats respectively. Based on these data the NAS
(Drinking Water. and Health) calculated the ADI to be 0.00075
mg/kg/day for 2, 1 4,5—TP. The accompanying Table No. 111—2
summarizes the studies used and the calculations to deter-
mine the ADI, and the suggested no—adverse reaction levels.
Chlorinated dioxins may be contaminants of 2, 1 4,5—TP.
Activated carbon was effective in reducing 2, ,5—TP to
below the MCL (Whitehouse, 1967) (Whitehouse, J. D., A Study
of the Removal of Pesticides from Water, University of
Kentucky, Water Resources Institute, Research Report No. 8,
Lexington, Kentucky, 1967).
The present drinking water MCL, 0.01 mg/l, for 2, ,5—TP
is in agreement with the above recommendations of the NAS.
Computation of an acceptable level for 2, 1 4,5—TP in drinking
water from the NAS recommendations would result in 0.0075
mg/i 2, I,5—TP in drinking water, if one assumes 10 kg weight
for an average child consuming 1 liter per day. Exemptions
up to 0.02 mg/i may be permitted until compliance can be
achieved. The sources of contamination should be

3. Toxaphene (0.005 mg/i)
Toxaphene has been detected but not quantified at least
once in finished water. Although there are some case
reports of acute Toxaphene poisoning, poisoning in humans is
rare. When Toxaphene was first used, four cases of
poisoning by ingestion in children under 11 year olds were
reported (McGee et al., 1952). The same study contained a
description of severe Toxaphene poisoning in adults after
its misuse in agriculture. The authors estimated that three
patients ingested Toxphene at 9.5 - 117 mg/kg.
Health Effects
Aside from accidental poisoning, human volunteers have
participated in Toxaphene toxicity studies. In one study,
50 human volunteers inhaled mist containing Toxaphene at
0.0011 mg/liter for 10 mm/day for 15 days; there were no
observed adverse effects (USEPA, 197 11 c). In another study,
a mist containing Toxaphene at 0.25 mg/liter of air was
inhaled by 25 people for 30 mm/day for 13 days; there was
no evidence of local or systemic toxicity (USEPA, 197 11 c).
Acute toxicity studies with Toxaphene have involved
oral, dermal, intravenous, intraocular, and inhalation
exposure. The toxicity of Toxaphene is influenced by the
solvent or vehicle used. When administered orally as a
solution or emulsion, it is more toxic in a digestable
vegetable oil than in an oil like kerosene. Toxicity of
Toxaphene by skin absorption is much less from an inert dust
than from an oily solution. The acute oral LD 50 is 90
mg/kg in male rats and 80 mg/kg in female rats; the acute
dermal LD 0 is 1,075 mg/kg in male rats and 780 mg/kg in
female ra€s (Gaines, 1960).
Administration of a 20% solution of Toxaphene in
kerosene to the eyes of rabbits and guinea pigs for 111
consecutive days produced mild irritation of the eyelids
with loss of hair around the eyelids. The eyes were not
injured, and the irritation in the eyelid was abated within
10 days (USEPA, 1974c). In acute inhalation studies, 110%
Toxaphene dust at 3.11 g/liter of air killed approximately
half the exposed rats within 1 hour.
Ortega et al., (1951) have studied the subchronic tox-
icity of To p ne in small groups of rats fed 50 and 200
ppm in the diet for 9 months. No clinical signs of tox-
icity, inhibition of food consumption, or growth rate were
evident. However, only the liver, spleen, and kidneys were

examined histologically. There was no apparent damage to
the kidneys or spleen, but 3 of the 12 rats that received 50
ppm showed slight liver changes, and 6 of the 12 rats fed
200 ppm showed distinct liver changes.
Degenerative changes in the kidney tubules and liver
parenchyma have been reported in dogs fed Toxaphene at low
dosages (Lacky, 19kg); two dogs received a k mg/kg/day (ab-
out 160 ppm) for kk days, and two others received the same
dosage for 106 days.
Chronic studies have been done in rats, guinea pigs,
dogs, cattle, sheep, and rabbits, In rats fed at 25, 100,
and kOO ppm in the diet for the conventional 2-year period,
only the liver showed significant changes, at 100 and kOO
ppm (Fitzhugh and Nelson, 1951).
Toxaphene was administered daily to dogs in a dry diet
for 2 years. When it was fed at kO ppm, there was slight
degeneration of the liver; at 200 ppm, there was moderate
degeneration of the liver (USEPA, 197kc).
Studies have also shown that, when Toxaphene is applied
to the skin of many large animals (including cattle, sheep,
goats, horses, and swine), adult animals can withstand high-
er dosages than immature animals. Also, application of cot-
ton patches treated with Toxaphene to the skin of 200 human
subjects caused no primary irritation or sensitization.
A three—generation reproductive study was conducted, ac-
cording to currently accepted protocol for rats, with Tox—
aphene at 20 and 100 ppm (Kennedy et al., 1973). No dif-
ferences between control and Toxaphene—treated animals were
reported, with respect to reproduction, performance, fertil-
ity, lactation, or viability, size, and anatomic structure
of progeny. In mutagenicity studies, occurrence of
mutagenic effects among the controls and the animals treated
with Toxaphene were similar. No evidence of carcinogenic
action was reported in any of the chronic—toxicity studies
previously undertaken.
An ADI at 0.00125 mg/kg/day was calculated by the NAS on
the basis of the chronic toxicity data. The available
toxicity data and calculations of the ADI by the NAS are
summarized in Tajle 111—3.
Activated carbon is 99% (plus) efficient in reducing
concentrations of the chlorinated hydrocarbon pesticides.
When maximum concentrations of the contaminant in raw water

do not exceed 20 ugh for endrin; 1400 ugh for lindane;
10,000 ugh for methoxychior; or 500 ugh for Toxaphene,
carbon treatment will reduce the concentration to the MCL.
It is assumed that the 10 kg child consuming one liter
of water per day is the individual most sensitive to
Toxaphene toxicity. Therefore, an MCL of 0.005 mg/i is
equivalent to an exposure of 0.0005 mg/kg body weight. The
MCL then provides a 2.5 safety factor when compared to the
recommended ADI suggested by the NAS (0.00125 mg/kg).
Exemptions up to the ADI (0.0125 mg/i) may be granted.
I4 Methoxychior (0.1 mg/i)
No residues of methoxychior were detected in 500 samples of
finished drinking water from the Mississippi and Missouri
Rivers (Schafer et al., 1969) or in 101 samples from Hawaii.
This compound has yet to be detected in drinking water.
Health Effects
The oral LD 50 In rats is over 6,200 mg/kg; that in
mice is 2,900 mg/kg; that in monkeys is over 2,500 mg/kg.
The dermal LD 50 in rabbits is over 2,800 mg/kg (USEPA,
1976e). The acute oral LD 5 ° of 2,2—bis—(p—hydrophenyl)—
1,1,1—trichloroethylene, the principal metabolite, In mice
is 600 mg/kg (Von Oettingen and Sharpless, 19146).
Methoxychlor chronically fed to rats at 10,000 ppm was
toxic, but fed at 5,000 ppm for 52 weeks produced mortality
comparable with that in untreated controls. There was some
growth retardation at 2,500 ppm and above, but no gross
pathologic changes were found. No tremors were observed at
any time (Haag et al., 1950). Methoxychior fed to rats for
2 years at 0.02 produced no abnormal gross pathology or
histopathologic changes (Haag etal., 1950). When fed to
beagle dogs at 1, 2, and 14 mg/kg/day over 6 months, meth—
oxychlor produced convulsions at the 2 and 14 g/kg level and
increased serum alkaline phosphatase and serum transaminase
(Tegaris et al., 1966). However, when fed at 300 mg/kg/day
for 1 yeai7 T i another study, it had no observed effects on
body weight, hematology, or histapathology (USEPA, 1976e).
The carcinogenicity potential of methoxychlor was
determined by the FDA. Methoxychlor fed in FDA studies for
2 years to C 3 He/FeJ and BALB/cJ mice at 750 ppm in the

I I I-. 30
diet showed no significant difference in incidence of
hepatocellular hyperplasia and hepatoma between controls and
treated mice. Testicular tumors were found in BALB/cJ mice,
and it was concluded from an histologic examination that
methoxychior caused a significant increase in the incidence
of this tumor in BALB/cJ mice, but not in C 3 He/FeJ mice
(USEPA, 1976e).
Rats fed methoxychior at 1,000 ppm in the diet had
normal reproduction. At 2,500 ppm, fewer rats mated, and
many did not produce litters. At 5,000 ppm, none of the
rats had litters or implantation (Harris et al., 19714).
Further studies with 200 ppm through three generations
showed no gross or histopathologic changes in any tissues
from rats of the F 3 generation.
Because of the possible resemblance of methoxychlor
detoxication phenols (2,2—bis—(p—hydroxyophenol)—1,1,1—
trichlorothane) to diethylstilbestrol, additional studies
were made to evaluate chronic feeding of methoxychior for
estrogenic effects. The results showed both no—adverse ef-
fect and uterine weight increase. The latter effect was
found to be at least partially due to an unidentified con-
taminant in technical methoxychlor (Tuliner, 1961).
Methoxychlor, a close relative of DDT, has very low mam-
malian chronic toxicity. In a 2—year feeding study no
adverse effect was observed at 200 ppm in rats. On the
basis of these chronic data an ADI was calculated at 0.1
mg/kg/day. The available data on chronic toxicity and
calculations of ADI are summarized in Table III— 4.
Activated carbon is 99% (plus) efficient in reducing
concentrations of the chlorinated hydrocarbon pesticides.
When maximum concentrations of the contaminant in raw water
do not exceed 20 ugh for endrin; 1400 ug/l for lindane;
10,000 ugh for methoxychior; or 500 ugh for Toxaphene,
carbon treatment will reduce the concentration to the MCL.
The present drinking water MCL, 0.100 mg/i, for
methoxychior is in agreement with the above recommendations
of the NAS and affords a safety factor of ten. The average
daily intake of methoxychior in the human diet was less than
0.001 mg over a given period. Therefore, the present MCL is
adequately protective of’ human health. The levels should
not exceed the present MCL of 0.100 mg/l.

5. Endrin (0.0002 mg/i)
Little is certain about the degradation and fate of en—
drin; however, traces of it and its stable epoxide oxidation
products are ubiquitous in the environment and are heavily
bioconcentrated in the lipids of terrestrial and aquatic
wildlife, humans, and foods, especially animal fats and
milk. Less than 1 million pounds of endrin was produced in
Because of the persistence of endrin and its degradation
products, they are found in virtually every surface water
(Drinking Water and Health, 1977). In an extensive
(1958—1965) survey of the rivers of the United States,
Briedenbach et al., (1967) found the average concentration
of endrin to be 0.008—0.21k ppb. The highest concentrations
were generally found in the lower Mississippi basin. In
196k, k6% were positive for endrin. More than 30% of
finished water samples contained endrin (Schaefer, et al.,
It was concluded by Richard, et al., (197k) that water
treatment plants were not removing substantial amounts of
pesticides from raw water.
The New Orleans water supply contained 0.00k ppb of
endrin (USEPA, 1975j). Endrin was also identified in some
other U.S. finished water supplies at concentrations of up
to 80 ppt.
Endrin is present everywhere in the environment, and is
readily biomagnified through food chains, and is a common
trace contaminant of human food. Market Basket Surveys of
the U.S. diet, collected in five major U.S. cities and
designed to simulate the diet of a 16—19—year—old male,
showed that, on the average, 0.001 mg/day was consumed. The
effects of endrin on animal and human health are very subtle
and complex. Endrin is one of the most hazardous of all
pesticides, because of its persistence, fat storage, and
central nervous system target site.
Health Effects
Human illness and death have been observed after
poisoning during the manufacture, spraying, or accidental
ingestion of endrin. Typical symptoms of poisoning result
from stimulation of the central nervous system and include
headache, blurred vision, dizziness, slight involuntary

muscular movements, sweating, insomnia, bad dreams, nausea,
and general malaise. More severe illness is characterized
by jerking of muscles or groups of muscles and epileptiform
convulsions, with loss of consciousness, involuntary
incontinence of urine and feces, disorientation, personality
changes, psychic disturbances, and loss of memory. Such
seizures may recur for 2 — 14 months after cessation of
exposure and are marked by abnormal encephalographic
patterns. These symptoms of severe poisoning have developed
in 10 — 20% of spraymen working in WHO house-spraying
programs (Hayes, 1957, 1959).
Epidemics of’ endrin poisoning have occurred after the
eating of bread made from flour accidentally contaminated
with endrin; there were 59 illnesses in one episode (Davies
and Lewis, 1956) and 8714, with 26 deaths, in Saudi Arabia
(Weeks, 1967). At least 97 cases of fatal endrin poisoning
were recorded through 1965 (USEPA, 1973a). It appears that
ingestion of endrin at 0.2-0.25 mg/kg can produce convul-
sions in humans (Hayes, 1963).
Oral LD 50 in male and female rats are 17.8 and 7.5
mg/kg respectively, but the dermal toxicity (15 mg/kg) is
roughly equivalent to the oral toxicity.
Endrin fed to rats at 1 and 5 ppm in the diet produced
no obvious effects over the life span, except for liver
enlargement at 5 ppm. When it was fed at 25 ppm, the life
span was shortened, and diffuse degeneration was seen in
brain, liver, kidneys, and adrenals. Mice fed endrin at
0.1—14.0 ppm over their life span showed increased liver
weights at 2 and 14 ppm and produced liver vascular damage.
Convulsions were observed in dogs fed 2 and 14 ppm, and
autopsies revealed pathologic changes in the brain (USEPA,
Endrin at very low dosages affects the central nervous
system, producing encephalographic changes and altering
Endrin was fed to rats at 2, 6, or 12 ppm in the diet
for 2 years without producing primary malignant hepatic
tumors or increasing tumor incidence in any organs
(Dieckmann et al., 1970).
Endrin has been subjected to the vigorous bioassay
program of the NCI and found negative. However, the NAS has
labelled endrin a suspect carcinogen (Drinking Water and

Activated carbon is 99% (plus) efficient in reducing
concentrations of the chlorinated hydrocarbon pesticides.
When maximum concentrations of the contaminant in raw water
do not exceed 20 ugh for endrin; 400 ugh for lindane;
10,000 ugh for methoxychior; or 500 ugh for Toxaphene,
carbon treatment will reduce the concentration to the MCL.
Endrin in drinking water using the MCL of 0.0002 mg/i is
less than 1/50 of the average daily consumption from food;
therefore, the contribution of water to the total body
burden is trivial. In the case of newborns (0 to 1 months),
neonates (1 month to 6 months) and babies, 80—100% of’ the
total daily intake may be in the form of baby formula. It
has been demonstrated that endrin has great bioaccumuiation
potential. It is for the above reasons that a conservative
value has been chosen. Therefore, exemptions up to 0.00014
mg/i may be granted for only minimal times. Steps to
eliminate endrin from the water must be initiated as soon as
6. Lindane (0.0014 mg/liter)
The relatively high water solubility and vapor pressure
of’ lindane cause it to have relatively low persistence in
the environment. Lindane has been detected in the finished
water ranging from non-detectable to 0.319 mg/i. On the
average lindane is not detected. Only five reportable
incidences have been above .0014 mg/i.
In the verage daily diet of’ the 16—19—year—old male,
12.22 X 1O mg/day was present. In cows’ milk 0.02 ppm
of lindane was present.
Health Effects
Over 30 cases of human exposure to BHC or lindane and 21
cases of exposure to BHC followed by the development of
aplastic anemia have been reported in the literature (Loge,
1965; West, 1967; Woodliff et al., 1966). No satisfactory
animal model simulating thatconditiOfl has been found and,
despite efforts to study the question, a firm causal
relationship between lindane or technical BHC exposure and
aplastic anemia cannot be confirmed. Development of
leukemia after lindane exposure was reported for two cases
(Jedlicka, 1958). That casual relationship is also
inconclusive in relation to insecticide exposure.

Lindane is the most toxic of the isomers of BHC. It ex-
cites the central nervous system, producing hyperirrita—
bility, incoordination, convulsions, and death due to
respiratory collapse. Its single—dose oral LD 50 in rats
is 88—300 mg/kg (Gaines, 1969; Riemschneider, 19119;
Burkatskaya, 1959; Slade, 19115; Kiosa, 1950; Woodward and
Hogan, 19117; Copper et al., 1951). The oral LD 50 of
technical BHC is 6ooT, 5o mg/kg; those of the other isomers
are about 1,500 mg/kg (a) 2,000 mg/kg (8), and 100 mg/kg (6)
(Reimschneider, 19119; Burkatskaya, 1969; Slade, 19115; Kiosa,
1950; Coper, 1951). The wide range in the observed LD 50
for lindane presumably results from differences in rates of
absorption of various preparations of’ the material and
variations in rates of detoxification and excretion under
different experimental conditions. Single oral doses of
10—25 mg/kg in corn oil were fatal to beagles (Cited in
USEPA, 1973b), and domestic animals were poisoned by similar
amounts (Wasserman etal., 1960).
Kliinmer (1955) administered daily doses of lindane, at
32 mg/kg of body weight, by stomach tube to male and female
rats for 6 months. He observed nervous symptoms, fatty
degeneration of the liver and renal tubular epithelium,
vacuolization of the cerebral cells, and a marked increase
in mortality. None of these effects was seen with a daily
dose of 10 mg/kg during 17 months. Melis (1955) fed diets
containing Lindane at 2, 3, 11, 5, or 10 ppm for 12 months to
rats and found no abnormalities in general behavior, body
weight, histology, or other characteristics.
Beagle dogs were not affected by lindane in the diet at
7.5 mg/kg/day (Cited in USEPA, 1973b). Higher dosages
produced central nervous system effects.
Under conditions of chronic administration, the y—isomer
is considerably less toxic than the other principal isomers
or technical BHC. Fitzhugh et al. (1950) conducted 2—year-
rat feeding studies with the various isomers of BHC, using
diets containing the a, , and y—isomers. These experiments
clearly showed that the y—isomer was the least toxic, and
the 8—isomer, the most toxic. The organs injured were the
liver and, to a lesser extent, the kidneys. In the case of
lindane, the lowest concentration causing significant liver
changes was 100 ppm; no effect was noted below 50 ppm.
Truhaut (19511) summarized data from 2—year feeding studies
in rats with lindane in the diet at 25, 50, and 100 ppm. At
25 ppm, no evidence of’ histologic changes in the liver or
kidney or any other toxic effects were seen. At the higher
concentrations, hypertrophy of the liver was observed, and,

at 100 ppm, a slight degree of fatty degeneration. These
findings and dose relationships were confirmed by other
workers (Ortega et al., 1957). FAO/WHO (1967) accepted 25
ppm in the diet of rats as the maximal concentration causing
no adverse effects.
The hypertrophic liver and fatty degenerative changes of
liver at higher dosage are similar to those produced by
other slowly metabolized organochlorine compounds. As might
be expected, lindane induces hepatic microsomal enzymes
(Freal and Chadwick, 1973). That effect may precede in time
and dosage relationship the liver pathology already
described (Hotterer and Schaffner, 1968).
The data on induction of liver tumors by y—BHC in mice
are seen to be somewhat contradictory. For example, Thorpe
and Walker (1973) found y’—BHC to be somewhat tumorigenic in
CF1 mice but the Japanese workers used other strains and
found that they were not susceptible to tumorigenic action
(Nagasaki et al., 1971, 1972a, 1972b).
The acute toxicity of technical BHC and BHC isomers also
differs greatly among various mouse strains; the CF1 strain
is particularly susceptible to acute poisoning (Miura et
al., 1971t). Such toxicity differences may be related to
different rates of’ metabolism of’ BHC; if’ so, the tumorigenic
effects may also be related. The relevant carcinogenicity
studies are summarized in Table 111—5.
The chronic toxicity of the BHC isomers is clearly
related to the tumorigenic effects so far observed only in
rodents. The y isomer is the most strongly implicated; its
activity is sufficient to account for the degree of hepatoma
formation observed with technical BHC administration in
mice. Lindane is a weaker tumorigen in mice, and is so far
a questionable tumorigen in the rat.
Activated carbon is 99% (plus) efficient in reducing
concentrations of the chlorinated hydrocarbon pesticides.
When maximum concentrations of the contaminant in raw water
do not exceed 20 ugh for endrin; 1400 ugh for lindane;
10,000 ugh for methoxychior; or 500 ug/l for Toxaphene,
carbon treatment will reduce the concentration to the MCL.
As of’ 1972, the FAQ/WHO ADI for lindane was set at
0.0125 mg/kg/day. Later, that value was reduced to 0.001

mg/kg/day and held under temporary status because of the
newer data concerning carcinogenicity. The FAO/WHO ADI for
total exposure is based only on chronic toxicity. There-
fore, the 0.0011 mg/i standard should not be exceeded for any
substantial period.
5. Radionuclides
The annual whole—body radiation dose in the United
States averages about 180 mrem/year (1). Environmental
sources average some 106 mrem/year via natural (102
mrem/year), fallout (11 mrem/year) and nuclear power (0.003
mrem/year). Medical exposures result in some 73 mrem/year,
72 mrem/year from diagnostic exposures and 1 mrem/year from
radiopharmaceutjcals. Some 2.8 mrem/year results from
miscellaneous sources including those encountered in the
workplace. The radiation dose to any individual may vary
substantially and is obviously related to his use of medical
services and where he lives. The natural radiation dose
varies markedly according to geological characteristics and
altitude whereby an individual in Colorado may well receive
an additional 100 mrem more than a person in Louisiana (2).
The relative contribution that radioactivity in drinking
water makes to ones overall radiation dose is small under
normal conditions. Nevertheless, it appears that the
radiation dose to the bone via a hypothetical water supply
in the U.S. is approxpnately 11 mrem/year, the m jority of
which comes from Ra 22 ° and the daughters of Ra 22 ° (2).
1. Combined Ra—226 and Ra—228 (5 pCi/l)
Radium—226 and Radium—228 are two naturally occurring
radionuclides from the uranium and thorium series. Radium
normally is found in groundwater of deep wells as opposed to
surface water. In the Midwest, primarily Iowa, Illinois,
Wisconsin and Missouri, the mean concentration of Ra—226
alone has been estimated to be approximately 5 pCi/i and the
Safe Drinking Water Committee of the National Academy of
Sciences suggests that in the entire U.S., over a million
people consume water that contains more than 3 pCi/i of
Ra—226 alone (2). Radium seldom occurs in surface waters
unless influenced by mining or other industrial operations.
Health Effects
Radium—226 and Radium—228, like other radionuclides, are
non—threshold carcinogens and pose a delayed threat to human
health usually from chronic ingestion. The risk of bone and
other cancers are linearly related to dose, and as a result,

will increase as the radium concentration increases in the
drinking water supply and in the body. Radium locates
primarily in the bone where 80—85% of the retained radium is
deposited. Other organs are also irradiated to a lesser
extent, however. The aggregate health risk from radium
ingestion estimated on the basis of lifetime exposure has
been estimated by summing the dose and resultant risk from
all organs. Risk estimates derived from the BEIR Report (1)
indicate that the incremental risk from continuous consump-
tion of drinking water containing Ra—226 and Ra-228 at the
MCL of 5 pCi/i may cause an additional 0.7—3 cancers per
year per million people exposed over their lifetimes.
Almost all of these cancers would be fatal. The risk of
drinking water containing greater concentrations of radium,
resulting in higher radiation doses, would increase
proportionally the number of fatal cancers.
Treatment techniques to remove radium are available (3,
li). Radium—226 has been demonstrated to be removed by
precipitative lime softening, ion exchange softening and
reverse osmosis with removal rates of 85%, 95% and 95%,
respectively. Using conventional technology, raw waters
having radium concentrations ranging from 5—100 pCi/i can be
used for drinking water and can meet the 5 pCi/l limitation.
The upper limit of the Federal Radiation Council (FRC)
Range II guide for transient rates of radiuin—226 ingestion
from both food and water is 20 pCi per day. Above this
range, evaluation and application of additional control
measures is always necessary (26 FR 9057, 1961). Provided
that a comparable intake of radium via the food pathway is
unlikely, exemptions for water supplies containing less than
10 pCi/i would be compatible with FRC guides. Occasionally,
exemptions for concentrations exceeding 10 pCi/i, for
strictly limited times, may be acceptable.
In granting exemptions and establishing schedules for
compliance, the primacy agency should consider the extent to
which the MCL for radium—22 6 and radium—22 8 is exceeded, the
number of persons at risk, the daily intake of radium from
sources other than drinking water and the duration of time
before compliance is likely to be achieved. Since treatment
methods are readily available, compliance schedules should
provide for early installation of treatment processes or for
the use of alternative water supplies.

2. Gross Alpha Particle Activity (15 pCi/i including
Ra—226 but excluding U and radon)
Finished drinking water contains such alpha particle
emitters as Ra—226, the daughters of Ra—228, Po—210, U, Th,
Rn—220 and Rn—222. The occurrence of Ra—226 is becoming
well documented. Special surveillance programs are identi-
fying the abundance of uranium and radon in water. The
occurrence of thorium mineral deposits and of Ra—228 and its
alpha emitting daughters needs further defining.
Health Effects
The degree of risk from ingestion of an alpha particle
emitting radionuclide depends on its specific chemical and
physical properties. Rather than require extensive radio—
chemical identification and measurement of all naturally—
occurring and man—made alpha emitters, the current Interim
Regulations require only the identification of radium—226
and are based on the conservative assumption that all of the
alpha—emitting activity is due to long half—life radionu—
clides. In many cases, the ingestion of 30 pCi/i of alpha
emitting contaminants, other than radium—226, will result in
substantially smaller doses to bone and other organs than
would occur from the ingestion of radium—226 at 10 pCi/l.
The dose equivalent to bone due to the chronic ingestion
of 10 pCi/l of radium—226 is about 300 mrem* per year.
Where analyses have identified the radioactive species,
other than radium-226, contributing to the gross alpha
concentration in drinking water, the 50—year dose to bone
due to ingestion can be calculated using the tables in NBS
Handbook 69 (5) as outlined in the Statement of Basis and
The ICR? model on alkaline earth metabolism indicates
that for equal intakes the 50—year dose to bone surface from
Ra—228 is significantly greater than that from Ra—226.
Experimental data used in the 1972 UNSCEAR report supports
this viewpoint. Since radium carcinogenicity Is associated
with the dose to bone surfaces, it is likely that Ra—228 is
more of a health risk than Ra—226. The measured relative
biological effectiveness of Ra—22 8 to Ra—226 in dogs appears
to be 2:1 when death via osteosarcomas is used as an end
* Assumes quality factor of 10.

point. While the relative carcinogenicity of Ra—228 to
Ra—226 may not be as great in man as in dogs, it is prudent
to assume that ingested Ra—228 is at least as dangerous as
Treatment techniques to remove Ra-226 are assumed to be
equally sufficient for the removal of Ra—228, Ra-223 and Ra—
22k. Precipitative lime softening, ion exchange and reverse
osmosis are the methods of choice.
Since treatment technology exists to readily remove
substantial quantities of radium from water, only exemptions
for radium contaminants need be granted. No provision is
made for variances. Exemptions for supplies having water
concentrations of gross alpha activity up to 30 pCi/i are
justified on the same basis as that provided for Ra-226 and
Ra—228 in Part A above. If a thorough analysis of the water
is performed to identify the alpha—emitting radionuclides,
exemptions may be appropriate for limited time periods if
the dose to bone from all alpha particle emitters, including
Ra—226, is less than 300 mrem per year even though the gross
alpha activity exceeds 30 pCi/i.
3. Man—Made Beta and Photon Emitters (k mrem per year)
Numerous man—made beta and photon emitters exist in
drinking water as a result of nuclear atmospheric testing;
disposal of radiopharmaceuticals from hospitals and research
institutions; the nuclear power industry, and from the
development of weapons. Since the Nuclear Test Ban Treaty
of 1963, there has been a significant decrease in the
corresponding radioactivity in surface water. With the
development of more medical facilities and procedures
requiring radiopharmaceuticals, the release of these
radionuclides will probably continue to increase. Assuming
a projected increase in energy requirements more beta and
photon emitters will undoubtedly be released from the
nuclear fuel cycle.
Strontium—90 and tritium are two among many radionu—
clides of concern in surface waters. Current data suggests
that Sr—90 in surface waters run about 1 pCi/i while tritium
in surface water rarely exceeds 1000 pCi/i (6).

111 1 10
Health Effects
Specific concentrations of radionuclides in drinking
water, (pCi/i) which are expected to result in a k mrem/year
dose to the critical organ or total body where two liters
are consumed per day, are specified in Appendix B -
Radionuclides of the National Interim Primary Drinking Water
Regulations (6). The NAS—BEIR risk estimates, using the
1976 U.S. population, would suggest that the incremental
population risk of a fatal cancer via lifetime exposures
resulting in a total body dose rate of mrem/year ranges
from about O. t—2 per million people exposed per year,
depending on whether the absolute or relative risk model is
used (6). The risk from the ingestion of water containing
higher amounts of radioactivity would result in proportion-
ally higher fatal cancers. Non—fatal cancers and genetic
disorders will also be increased with higher exposures.
Treatment for the removal of beta or gamma emitters
should be based upon chemical rather than radioactive
characteristics of the contaminant. Ion exchange and
reverse osmosis can remove a broad spectrum of ions and
molecules from water, and consequently are the methods of
choice. Some radionuclides, like tritium oxide, are not
removable by any practical water treatment process.
Neither variances or exemptions should be necessary
except in cases of malpractice. In cases where a water
supply has been contaminated via chronic or intermittent
releases, a variance or exemption may be necessary for a
limited period of time to insure an uninterrupted supply of
water for drinking and other purposes.
Current federal guidance for transient rate of intake
provides limitations on food and water intake that are
comparable to an annual dose equivalent of 50 mrem/year and
contain a recommendation that for transient situations the
dose should be averaged over one year (26 FR 9057). The
variance and exemption limitation shall not exceed 50 mrem/-
year to any organ from radioactivity in finished drinking
water (12 times EPA k mrem/year standard). The maximum dose
commitment for any one day from radioactivity in drinking
water shall not exceed 10 mrem.

III— k 1
The 50 mrem/year limitation can be assumed to be met if
at least one of the following analytical procedures results
in a screening level concentration(s) of less than those
specified below:
Gross beta with iodine precipitated - 0 pCi/i
Gross beta without iodine precipitated — 100 pCi/i
(Separate radioiodine tests may be needed)
Should the screening level be exceeded a complete
radiochemical analysis may be used to determine whether or
not the finished drinking water exceeds the 50 mrem/year
limitation. For continuous intake, concentrations of a
single man—made radionuclide yielding 50 mrem/year to any
specific organ can be found by multiplying by 12 the concen-
tration listed in the National Interim Primary Drinking
Water Regulations (NIPDWR), EPA—570/9—76—003, Appendix B.
When more than one radioriuclide is present, instructions for
limiting their sums are given on page 153 of the NIPDWR,
Appendix B. For continuous intake, an annual dose rate of
50 mrem results from each of the following concentrations:
Strontium—90 100 pCi/i
Strontium—89 1,000 pCi/i
Cesium—137 2,000 pCi/i
Iodine—131 kO pCi/i
Radiochemical identification will be required to
determine if the individual dose commitment from one day’s
intake (2 liters) exceeds 10 mrem. A 10 mrem dose commit-
ment results from each of the following concentrations:’
Strontium—9O 7,000 pCi/i
Strontium—B9 70,000 pCi/i
Cesium—137 200,000 pCi/i
Iodine—131 3,700 pCi/i
Some acute contaminating events can lead to immediate
exposures that will cause relatively high doses over an
extended period of time. The granting of exemptions is not
amenable to emergency conditions following large accidents.
In such cases, the appropriate controlling authority should
impose protective actions (29 FR 12056). Protective actions
are appropriate when the health benefits associated with the
reduction in exposure to be achieved are sufficient to
offset the undesirable features of the protective action (30
FR 6953). Such balancing must be made on a case-by—case
sis, probably in consultation with several Federal and
State agencies, since the impact of food, air, water and
* Concentratons causing a 10 millirem dose commitment are
9000 times those given in Appendix B of NIPDWR.

possible direct radiation must be considered in selecting
the appropr iate action level for a particular situation ( O
FR 5959k). A Federal Task Force is currently reviewing
emergency response planning for radiological incidents. As
protective action guides are developed under this program,
additional guidance to the States on the granting of
variances and exemptions may be forthcoming.*
* Note FDA Proposal — Federal Register , Vol. No. 242,
pages 58790—58800.

I I I— l 3
(1) “The Effects on Population of Exposure to Low Levels of
Ionizing Radiation” (BEIR Report), National Academy of
Sciences, National Research Council, Washington, D.C., 1972.
(2) “Drinking Water and Health,” Safe Drinking Water
Committee, National Academy of Sciences, National Research
Council, Washington, D.C., 1977.
(3) “Determination of Radium Removal Efficiencies in Water
Treatment Processes,” U.S. EPA (ORD/TAD—76—5), Washington,
(II) “Treatment Techniques for the Removal of Radioactive
Contaminants from Drinking Water,” Gary S. Logsdon, Health
Physics 35(6):918.
(5) “Maximum Permissible Body Burdens and Maximum
Permissible Concentrations of Radionuclides in Air and Water
for Occupational Exposure,” NBS Handbook 69, Department of
Congress, revised 1963.
(6) National Interim Primary Drinking Water Regulations,”
U.S. EPA (EPA—570/9—7 6 —0O3, ODW), Washington, D.C.

The issuance of a compliance schedule is an integral
part of the procedure that must be followed by a primacy
agency that grants a variance or an exemption from an MCL.
In fact, Sections 1 4 15(a)(1)(D) and 1 t16(b)(3) of the Act
require that any variance or exemption be conditioned upon
compliance by the public water system with the prescribed
schedule. The requirements of each schedule must then be
enforceable by the primacy State under its laws and may be
enforced under Section 1k14 of the Act as if such require-
ments were part of’ the National Primary Drinking Water
Sections 1 1 415(a)(1)(A) and 1’116(b)(1) require that the
compliance schedule be prescribed within one year of the
date the variance or exemption is granted {See also O CFR
S1Lt2.k3(g) and S1 42.53(d)j. Those sections of the Act
further require that such a schedule provide for:
1. compliance (including increments of progress) by the
public water system with each contaminant level
requirement with respect to which the variance or
exemption is granted as expeditiously as practicable;
2. implementation by the public water system of such
control measures as the primacy agency may require
for each contaminant, subject to each contaminant
requirement, during the period ending on the date
compliance with such requirement is required.
Thus, it is expected that a compliance schedule will include
all steps necessary to achieve compliance with appropriate
milestone dates to ensure that the public water system is
making diligent efforts to bring itself into compliance as
expeditiously as practicable.
In the case of a variance, the compliance schedule
should include, as a minimum, the following specific dates,
where appropriate:
(i) Date by which arrangement for alternative
raw water source or improvement of existing
raw water source will be completed;
(ii) Date of initiation of the connection of the
alternative raw water source or improvement
of existing raw water source; and

IV- 2
(iii) Date by which final compliance is to be
If either a variance or exemption is granted, the
compliance schedule should include appropriate interim
measures including control of’ the contamination source and
other means designed to minimize the danger of exposure for
all persons or at least for particularly susceptible per-
sons. These may include interim treatment measures,
notification to physicians and susceptible individuals,
increased public health surveillance and provision of
drinking water through alternative sources, such as bottled
water, where necessary.
Since the completion of various steps necessary to
achieve compliance will depend on a number of factors, it is
appropriate to consider each factor and its relative impor-
tance to a given situation. The following factors should be
considered by the primacy agency in prescribing a compliance
schedule, keeping In mind that compliance should be achieved
as expeditiously as practicable. The established time
frames must above all be reasonable relative to the particu-
lar circumstances.
1. Health and safety of’ consumers of water : It is of’
utmost importance to consider the acute or chronic
health effects that might be Induced by an unduly
long compliance schedule.
2. Technical
(a) Time to study the problem and recommend a
(b) Time for user participation and Input;
Cc) If modifications to existing treatment
facilities or construction of new facilicites
are indicated by the studies, the time to
complete design and to obtain necessary
permits, to let contracts and work out
contractual arrangements, and to install
equipment should be considered;
(d) Time for delays due to Inclement weather
or labor problems; and
Ce) Time for testing and start—up.

3. Economic
The time necessary to arrange financing of the
contemplated improvements should be considered in
setting up the milestone dates in the compliance
I. Legal and Administrative
Unavoidable delays due to legal and administrative
requirements should be anticipated and provided for
in the compliance schedule.
5. Other
Other pertinent and/or unique factors which bear on
the water system’s compliance schedule should be
6. Extensions
Extensions to an established compliance schedule
should be granted by the primacy agency only when
the public water system has demonstrated good
cause, is acting in good faith, and the
circumstances otherwise warrant. In the case of an
exemption, extensions cannot be granted beyond the
statutory deadlines.
Please note two typographical errors in O CFR Part 1 2:
1. 4O CFR 1L 2i 3(b)(1) — The reference in the last
line of the paragraph should be changed from
“Section 1l .1.1414” to “Section
2. 4O CFR 1L 2.51I(d) — The next to the last line of the
paragraph should be changed from “5 days” to “15
Compliance Deadlines
In addition to considering the practical constraints
that will bear upon the length of a compliance schedule as
described above, the primacy agency must also be guided by
the statutory time limits established under the Safe Drink-
ing Water Act. No compliance schedule may extend beyond the
dates established under the Act. Nor should it be so short
that the necessary steps taken to achieve compliance cannot
be completed due to unavoidable technical, legal or admini-
strative delays.

With respect to variances, the Act contains no
statutorily mandated deadline by which time compliance must
be achieved. Due to the kind of problem variances were
intended to address, the establishment of a specific
time—limit in any given situation will depend largely on the
availability of an alternative raw water source or the
existence of new treatment technologies with greater removal
efficiencies which are capable of achieving the established
maximum contaminant levels. Nevertheless, compliance dead-
lines should be imposed by the primacy agency whenever it is
feasible to do so. In any event, compliance should be
required to be achieved as expeditiously as practicable by
incorporating such language into the variance. The schedule
may therefore specify an indefinite time period for
compliance until a new and effective treatment technology is
developed at which time a new compliance schedule will be
prescribed by the primacy agency. Periodic evaluations of
issued variances should be conducted to ensure that the
timeframes are still reasonable, no unreasonable risk to
health is involved and the basic conditions surrounding
their issuance continue to exist.
Unlike variances, in the case of exemptions, Section
11416 clearly requires that compliance schedules must contain
a final compliance deadline of not later than January 1,
1981 (or January 1, 1983, if the supplier of the public
water system has entered into an enforceable agreement to
become part of a regional water system). Where it is prac-
ticable for a public water system to come into compliance
earlier than the statutory deadline, the exemption schedule
should specify the appropriate earlier compliance date.
Whereas in most cases, compliance will be achievable within
the statutory timefraine, in a relatively few number of
cases, EPA recognizes that compliance will not be feasible
by January 1, 1981, nor will regionalization be feasible to
allow an extension of the deadline to January 1, 1983. The
timeframe also becomes increasingly critical as the National
Interim Primary Drinking Water Regulations are amended. In
light of these concerns, EPA is proposing amendments to
Section 11416 of the Safe Drinking Water Act which would
extend the compliance deadlines for exemptions beyond the
1981 and 1983 dates presently specified.
During this period, before Congress can take legislative
action with regard to the exemption deadlines, the primacy
agency must establish exemption schedules consistent with
the existing statutory provisions. In those cases where a
public water system can demonstrate that the 1981 deadline

IV- 5
cannot be met despite all reasonable efforts to do so, and
has demonstrated good faith efforts to comply with the
regulations since they were promulgated, the primacy
agency’s enforcement discretion should be carefully
exercised. In the short term, it may also be possible for
the primacy agency to delay issuance of the compliance
schedule for one year following the issuance of the
exemption or to delay inclusion of a final compliance
deadline in the schedule for that year, at which point in
time further legislative guidance will be forthcoming. This
guidance document will be revised to reflect any statutory
amendments at that time.




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As a practical matter there may be a substantial delay
between the time that a violation is detected, determination
by the water supplier that a variance or exemption is the
desired course of action, and a decision is made by the
primacy agency to grant or deny the request. In such cases,
it may be appropriate for the primacy agency, after it has
determined that there is no unreasonable risk to health, to
develop and implement a compliance agreement with the water
The compliance agreement should acknowledge that there
is no unreasonable risk to health, outline the necessary
actions to be taken by the water supplier and EPA in the
interim period and allow deviation from the MCL until the
variance or exemption is granted or denied by the primacy
agency. Such actions may include increased public notice,
special notice to physicians and provisions for bottled
wa t e r.
There is also another situation where a compliance
agreement could be utilized. If the primacy agency has
determined that there is no unreasonable risk to health and
it appears the water supplier can be in accordance with the
Interim Primary Drinking Water Regulations within a short
time frame (a few months), it is prudent to eliminate the
complex variance or exemption process. This allows more
flexibility, and reduces the resource demand (i.e., paper-
work, manpower), and at the same time, maintains reasonable
public health protection.
It should be understood that such administrative actions
are not explicitly included in the provisions of the Safe
Drinking Water Act and care must be exercised to ensure that
the conditions of the compliance agreement are as least as
stringent as those associated with a variance or exemption.
Parties to a compliance agreement should be aware that the
protection from enforcement action, including citizen suit,
provided by exemptions and variances, is not in effect.
* U. S. GOVER1 MENT PRIN1 U G OFFICE 1979 281-147/102