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"
O
nly t h
eh i g h
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ap
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cle
energ y i
sh
st ed
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nly t h
em
ost p
reval
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be
ta
p
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cl
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axi
mu
m
e n erg>
'i
sh
sted
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d
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ath
s; p
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e show
nis
fo
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d
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p
ath
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(
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1 9 8 3
;
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al k
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h
eh
om
eA
l
a rg
e n um b
e r of p
ub l i
cw
at
e r s up
p l i
e s u s eg
r o u nd w
a t
e rt
h
a
t
is c o n
t
am i
n at
ed w it
h
n a
t
u r al l
y
-o c c u r rin
g
r ad i
o a ct
iv e s u
b
st
a n c e sW
h
e nt
h
e s e c o nt
am i
n a nt
s u nd
e rg
o r ad i
o a ct
iv e
d
e c ay
in
t
h
eb
od
y
,t
h
ey
m
ay
i
n c r e a se t
h
e ri
sk
of
c a nc
e rW
h
e n ra
d
o n-
la
d
e nw
at e
ri
s u s ed i
nt
h
eho
m
e(
b
at
h i
ng
, c o ok in
g
,w
a sh i
ng
, et
c)
^ ^^R
ng
a s e s c ap
e si
nto
t
he
air
I
t
is e s
t
im
at
ed
t
h
at
1 0
,0
0 0
p C i/
L
of
'^ ^R
nin
w
at
e rw i l l
c o nt
ri bu
t
e ab
o ut
1
p C i/
L t
oin
d
o o r air
in
a n a v e r ag
eh
o u s e(
H
e s s, et a
l
,19 8 5 ; E P A
,1 9 9 1b
)
I
nh
al
ati
o n of
t
h is
^ ^ ^R
n, a nd
a s s o cia
t
ed p
r og
e ny
,m
ay
in c r e a s e
t
h
e ri
sk
of
lu n
g
c a n c e rA
l
s o,d
i
r e ct
in
g
e st
i
o n of
r ad
o n-
l
ad
e nw
at
e rm
ay p
r e s e nt
ac a n
c
e r ris
k
t
ot
h
e stom
a ch
a nd
ot
h
e rin
t
e r n al
o rg
a n s(
E P
A
,1 9 9 1a
)
T
h
eSa
f
eD
rin
k i
ng
W
a t
e rA
ct
(
SD
W
A
)
A
m
e nd m
e nt
so
f
1 9 8 6
r eq
uir e
d
t
he
U
nit
ed
St
at
ed
E
n vir o n
m
e nt
al
P
r ot
e ct
i
o nA
g
e n cy
(
U S E
P
A
)
t
os
et
a st
a nd
a rd f
o r ^ ^ ^R
nT h
eU S E
P
A
w
a s c om
p
el l
ed b
y
t
h
e "n o -ris
k
"la n
g
u ag
e of
t
h
eSD
W
A A
m
e nd m
e nt
st
op
r op
o s e r eg
ul
ati
o n sl i m it
i
ng
^ ^ ^R
ni
np
ub li
cw
at
e r s up
p
l i
e st
o a ri
sk l
e v el
c o n si
st
e nt
w i
t
h
oth
e r c a r cin o
g
e n si
nw
ate r
H
e n c e,E P A p
r op
o s ed l i m i
t
in
g
^ ^ ^R
nin
w
at
e rt
o al
e v el
of
3 0 0 p
C i/ L
(
1 1 1 B q
/L
)
(
E
P A
,1 9 9 1a
)
T
h is
p
r op
o s ed l im i
t
w
as
e st
i m
at
ed
t
op
re
v e nt
84
of
th
e es t
i m
at
ed
19
2
a
n n u al
c a n c e r c a s e s a
t t
rib
ut
ab le
t
o ^^ ^R
nin
w
at
e r(
U S C
o ng
re
s s,1 9 9 5
)
H
ow
e v e r, o n a v e r ag
e, ^ ^ ^R
n e nt
e rin
g
ah
om
et
hr o u
g
h
t
h
ew
a t
e r s up p
l
y g
e n e r al l
y
c o n
t
ri bu
t
e sle s s
t
h
a n5
p
e r c e nt
of
t
h
e ^ ^ ^R
ng
a si
ni
nd
o o r air
(
E
P
A
,1 9 9 1b
) W
it
h
a n a v e r ag
ein
d
o o r ^ ^ ^R
n c o n c e nt
r at
i
o n of
1
p C i/ L
(
Sh
a
p i
r o ,1 9 9 0
)
,t
h is
m
e a n sg
r o u nd w
at
e rc
o nt
ri b
ut
e sa
p p
r o xi m
at
el
y 0 0 5 p
C i /L
t
oin
d
o o r air
, a n am
o u nt t
h
at
is
le s s
t
h
a nt
he
0 2
t
o0 7 p
C i/
L
a v e r a
g
e c o n c e nt
r at
io n
of
^ ^ ^R
ni
n o ut
d
o o r air
(
E
P A
,1 9 9 1b
)
T h
ep
ri
n ci
p
al
s o u r c e of
^ ^^S
D
W
A
(
S
1 3 1 6
)
T hi
sb i l l
s
et
st
h
eli
m i
t
f
o r ^ ^^R
na t
3 0 0 0
p
C i
/L
, r ep
r e s e nt
i
ng
a ri
sk
l
e v el
c o
m p
a r ab le
t
ot
he
ris
k
of b
r e at
h i
ng
^^ ^R
ni
n o ut
d
o o r ai
rC
o ng
r e s s r a r ely
s et
s s u ch
l
i m i
t
sd i
r e ct
l y
, n o rm
al l
y
l
e a vin
g
s u ch m
at t
e r st
oE
x e c ut
iv e
B
r a n ch
ag
e n cie s s u c
h
a st
h
eU S
E P A
O
n c et
h
e r eg
ula
t
io n s
f
o r ^ ^ ^R
nin
d
rin
k in
g w
at
e r a r e e n a ct
ed
,
p
ub l i
cw
at
e r s up p l i
e r su s
i
ng g
r o u nd w
at
e rw i ll b
e r eq
ui
r ed
t
o s am
p
le
p
e ri
od i
c al l
y
t
od
em
o n st
r at
e c om p l i
a n c ew i
t
h
t
he
r eg
ula
t
io n
T
he
f
o c u s of
t
hi
s st
ud
y
w
a st
od
et
e rm i
n ei
f
t
h
ep
r op
o s ed
s am
p
l in
g
s ch
ed
ul
ei
sa
d
eq
u at
et
o ch
a r a ct
e ri
z et
h
e ^ ^ ^R
n a ct
i
vi
t
y i
ng
r o u nd w
at
e r s o u r c e sA
n al
y
si
s of w
at
e r s am
p l
e sw
a sb
a s ed
o nm
et
h
od
sd
e v elo
p
ed b
y P
ri
ch
a rd
a nd G
e se
l l
(
1 9
7
7
)
f
o r u si
ng l i q
ui d
s ci
nt
i l l
at
i
o n c o u nt
in
g
f
o r a n al
y
sis o
f
^ ^ ^R
ni
nw
at
e rT
h
em
et
h
od
sin
t
h
e c u r r e nt
st
ud
y
d i ff
e r ed fr
om
t
h
eP
ri
ch
a rd
a nd G
e s el l m
et
h
od i
nt
w
oi m p
o rt
a nt
w
ay
s :(
1
)
m i
n e r al
oi l
-b
a s ed
(
i
n st
e ad
of
t
olu e n e
-b
a s ed
)
s cin
t
i l la
t
i
o nfl
ui d w
a s u s ed
a nd
(
2
)
w
a t
e r s am p l
e sw
e re
c oll
e ct
ed b
y
slo
w l
y
fi l li
ng
e a ch
via
l d ir e c
t
l y f
r om
a sp ig
ot
at t
h
ew
el l h
e
ad
(
i
n st
e ad
of b
y
L I T E R A T U
R
E
R
E V I E
W
L
eg
i
sl
at
i
v e a nd
R
e e ul
at
o r vB
a
ck
g
r o u nd
T
h
e o ri
g i
n al SD
W
A
of
1 9 7 4
(
f
o rm
al l
y
k
n ow
n a sT
it
le
X
I
V
of
t
he
P
ub l i
cH
e al
t
h
Se r v
i
c eA
ct
)
g
a v et
h
eU S E
P
A
t
h
e st
atu
t
o ry
m
a nd
at
et
o r eg
ul
at
e c o nt
am i
n a nt
sin
d
rin
k i
ng
w
at
e rU
nd
e rt
h
eA
ct
, c o nt
am i
na
nt
sw
e r ed
efi
n ed
a s "a n
y
p hy
si
c al
, ch
e
m i
c al
,b
i
ol
og
ic a
l,
o rr a
d io
l
og i
c al
s ub
st
a n c e o rm
at
t
e rin
w
a t
e r "I
n1 9 7 6
, r eg
ula t
io n s
w
e r ep
a s s ed
c o ve
rin
g
^ ^ ^R
a,^^ *
R
a,g
r o s s al
p
ha
p
a rti
cle
r ad io a c
ti
vit
y
, a nd b
eta
a nd p h
ot
o n r ad io a c
t
i
vit
y
H
ow
e v e r, ^ ^ ^R
nw
a s e xp
l i
cit
l
y
e x clu
d
ed fi
"o
m
t
h
e s e r eg
ul
at
io n s
d
u et
ot
h
e u n ce
rt
ai
nt
ie s
a
b
o ut
t
h
e ris
k
of
^^ ^R
nin
d
ri
nk i
ng
w
at
e r, c o nt
r ol
t
e ch
no
l
og i
e s,a
nd
t
re
atm
e
nt
co s t
s(W
i l l i
am
s
,19 9 5
)
T h
est
at
ut
o ry
m
a nd
at
ef
o
r r eg
ul
at
i
ng
^ ^ ^R
ni
np
ub l i
cd
ri
nk i
ng
w
at
e rsu
p p
l i
e sfi
n al l
y
c a
m
efi
^o
m
Se c
t
i
o n1 4 1 2
(
b
)
of
t
h
eSD
W
A A m
e nd
m
e nt
s of
1 9 8 6
T h i
s
r eq
ui
r ed
t
h
eU S
E
P A
t
o "p
ub l i
sh
M
a xi
m
um
C
o nt
am i
n a nt
L
e v el G
o al
s(
M
C L G
s)
a nd p
ro
m
ulg
at e
N
at
io n a
l P
ri m
a ry
D
ri
nk in
g
W
a t e
rR
eg
ul
at
i
o ns
(
N P D
W
R
s)
f
o r c o nt a
m in a n
t
si
nd
ri
nk i
ng w
at
e rw h i
ch m
a
y
c a u s ea n
y
ad
v e r s e ef f
e ct
o nt
h
ehe
alt
h
of p
e
r s o n s a nd w hi
ch
a
r ek
n ow
no
r a nti
ci p
at
ed
t
oo
cc
u ri
np
ub li
cw
at
e r sy
st
em
s " ^ ^ '^R
nw
a s cla
s
si fi
ed
a s aC la s s
A
c a r cin o
g
e n;
t
he r e
f
o r e, c o n si
st
e nt
w it
h
o
t
h
e r ca
r cin o
g
e ns,
i
t
h
ad
a nM
CL
G
o
f
z e r o(
E
P A
,19 9 1
a)
I
n1 9 8 6
,t
he
E P A
p
r op
o s ed
aM
a xi m
um C
o nt
am i
n a nt
L
e v el
(M
C
L
)
f
o r ^ ^ ^R
n of
3 0 0
p C i/ L
T
h
el i m it o
f
3 0 0
p C i /
L
w
a sb
a s ed
o
n a n e st
i m
at
ed l if
et
i m
e ri
sk
of
2
x1 0
"'*(
E P A
,19
9 1
a)
T h is r
is
k le v e
l is c
lo s
e t
ot
h
el O
"'*to
1 0
"*r
is
k
ra
ng
e(
"n o-ri
sk
"l
e ve
l
)
th
at t
h
eE
P
A h
a shi
st
o ric a
l l
y
u s ed
t
o s et
l i m i
t
sf
o rw
at e
rb
om
e c o nt
am i
n a nt
s(
E P A
,1 9 9 1
a
)
T
h
e ris
k
e st
i m
at
ew
a sb
a s ed p
rim
a ri l
y
o nt
h
el if
et
i m
el
u ng
c a n c e r ri
sk fi
-o
m i
nh
al
at
i
o n of
^^ ^R
np
r og
e ny
r ele a s e
d
fi
"l
ab
o r at
ori
e sT
h
eP
Q
L
i
s n ot
ad
et
e ct
io
nl i m it
f
or ap
a rt
i
c ul
arp
r o c ed
u r e at
ap
a rt
i
c ul
a rl
ab
o r at
o ry ; i
n st
e ad
,it
i
s al
e v el
of d
et
e ct
io n
t
h
at
E P A
b
el i
e v e s c a nb
e a ch ie v e
d
at
m
o st
q
u al i fi
ed l
ab
o r at
ori
e sP
Q
L
a nd
r el
at
ed
c o n c ep
t
s a r ed is c u s s e
d i
nm
o r ed
et
ai l i
nA
p
p
e nd ix
E
T
h
eE P
A p
ub l i
she
d
t
h
e
p
r op
os
ed
r eg
ul
at
i
o n sin
th
eF
ed
e r al R
eg i
st
ry
o nJu
l
y 1
8
,1 9 9 1
f
o rin
c
lu s
io n
in
4 0
C F R
P
a rt
s14 1
a nd
1 4 2
w i
t
h i
m p
l
e
m
e nt
at
io n
b
eg i
n nin
g
o nJa n u a r
y
1
,1 9 9 6
T
h
e r eg
ul
at
io n s
w
o ul
d
ap
p l
y
t
o al l
c om m
u nit
y
(
i
e,
m
o
r et
h
a n1 5
c o n n e ct
io n s o r
s
e
r vi
ng m
o r eth
a n2 5 p
e r s o n s)
a nd
al
l
n o n-t
r a n si
e nt
, n o n-c o
m m
u ni
t
y p
ub l
i
cw
at
e r sy
st
em
s(
i
e , r e st
a u r a nt
s, s e r vic e
st
at
io n s
, et
c)
T h
ep
r op
o s ed
r eg
ula t
i
o n sw
o
ul d
n ot
ap p l
y
t
op ri
v at
ew
at
e r sy
st
em
s(
E P A
,1 9 9 1
a)
I
n1 9 9 2
,C
o ng
r e s s at t a
ch
ed
t
h
eC h
aff
e -L
a
ut
e nb
e rg
am
e nd m
e nt t
ot
h
e
E P A
a
p p
r op ri
at
i
o n sb il l
I
np
a rt
,t
h is a
m
e nd m
e nt
e xt
e nd
ed
t
h
ed
e ad li
n ef
o ri m p l
em
e nt
i
ng
t
h
eE
P
A
's
p
r op
o s ed
^ ^ ^R
n r eg
ul
at
io n s a n
d
r eq
uir e
d
t
he
E
P
A
t
op
r ep
a r e a r ep
o rt
t
oC
o ng
r ess o n
t
h
e
ris
k
a n
d
r eg
ul
at
o ry
a ct
i
o n s a s s o ci
at
ed w i
t
h
^ ^ ^R
nT
h i
s r ep
o rt
w
a sp
re
s e nt
ed i
n1 9 9 4
A
s
st
at
ed p
r e vio u s
l
y
,
t
h
eSe n a
t
ep
a s s ed
abi l l i
n1 9 9 5
s et t
in
g
t
h
e ^^ ^R
nl i m i
t
at
3 0
0 0
p
C i/
L
A
lt
h
o ug
h
t
h
eri
sk le v e
l i
s at
l
e a st
1 0
t
i
m
e sh i
g
h
e rt
h
a nf
o r ot
h
e r c o nt
am
i
na
nt
sc o n
t
r ol l
ed b
y
t
h
eSD
W
A
,it
r e c og
niz e s
t
h
ef
a ct t
h
at t
h i
sl
e v el
o
f
^ ^ ^R
nin
w
at
e
rp
o se
sa
p
p
r o xi m
a t
el
y
t
h
e s am
eri
sk l
e v el
a sd
o e s e xp
o s u r et
o ^ ^ ^R
ni
n n o rm
al
o ut
d
o o r ai
rU
nd
e rt
he
p
r op
o s ed
r eg
ul
at
i
o n,w
at
e r s up p
l
y
sy
st
em
st
h
at
u s eg
r o u ndw
at
e r(
p
a rt
l
y
o re n
t
ir e
l
y
)
w
o ul d i
ni
t
ia
l l
y
h
a
v et
o s am p l
ef
o r ^^^R
nd
u rin
g
f
o u r c o n s e c ut
i
v eq
u a rt
e r sf
o rt
he
fi
r st
y
e a r of
s am p l i
ng
, a nd
t
h
e n a n n u al
l y
f
o
rt
h
e n e xt t
w
oy
e a r s(
i f
th
e a v e r ag
e of
t
h
efi
r st
y
e a rs a
m p l
e s a r ew it
h i
nl i m i
t
s)
C
om
p
lia n c e
w
o ul d b
ed
em
o n st
r at
ed b
y
t
h
e a rm
u al
a v e r ag
eS
am
p
l
e sw
o ul d b
e t
ak
e n at t
h
ew
el l
o r at t
h
e e nt
ry
p
oin
t t
ot
h
ed is
t
ri
bu
t
i
o n sy
st
em S
y
stem
sfa
i li
ng
t
om
e et t
h
e
st
a nd
a rd
w
o ul d b
e r eq
ui
r ed
t
oi
m
p l
em
e nt
B
es t
A
v ai l
ab le
T
e ch
n olo
g
y
(
e.g
. ,a
e
r at
i
o
n)
, u nle s s
e
x em p
t
ed
(
E
P
A
,1 9 9 1
a)
T
w
o s am
p
l
i
ng m
et
h
od
s a r ep
r op
o s ed i
nt
h
e r eg
ula
t
i
o n sf
o rq
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i f
y
i
ng
^ ^ ^R
nin
w
at
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p
p l
i
e s :t
h
eL
u c a s c el l m
et
h
o
d
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ui d
s ci
nti ll
at
i
o n c o u nt
in
g
(
L
S C
)
L S C i
st
h
eq
ui
c
k
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o st
c o n v e nie n
t
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e c o n om i
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et
h
od f
o rl
a
rg
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le s
a
m p l i
ng
a nd w
a s u s ed f
o rt
h is
R
el
e v a n c e of C
u r r e nt
St
ud y
Sin c e c o
m
p
l i
a n c ew it
h
t
he
n ew
^ ^ ^R
n st
a nd
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e v e nt u
al l
y
r eq
u
i
r e o nl
y
o n eg
r ab
s a
m
p
le
t a
k
e n o n c e ay
e a r,it
is o
f i
nt
e r e st t
o u nd
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a nd h
ow
cl
o s el
y
a ny
sin
g l
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et a
k
e nd
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t
h
ey
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at
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ot
h
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eT
h is s
t
ud
y
c o nt
in u e
d
t
h
e r e s e a r ch
c o nd
u ct
ed b
y
H
ig
ht
ow
e r(
19 9 4
)
a nd Y
o rk
(
1 9 9 5
)
t
o e v al
u ateh
ow
^ ^^R
n c o n c e nt
r at
io n s
i
n s am
p
l
e sf
r om
p
ub
Hc
w
at
e r s up
p
l ie s v a r
y
am
o ng
s am
p l i
ng
r u n sm
ad
e ap p
r o xi m
at
el
y
e v e ry
t
w
o
w
e ek
sd
u rin
g
t
h
ey
e a rB y
co
m b i
ni
ng
t
h
ed
at
af
r om
t
h
e s et
w
o st
ud i
e sw i
t
h
t
h
o s e ob
t
ain e
d fr
om
t
h
e c u r r e nt
s
t
ud
y
, a n e st
i m
at e
of
t
h
e a v e r ag
e ^^^R
n c o n c e nt
r ati
o
nf
o r e a ch w
el l w
a
s c al
c ula
t
ed
a nd
t
he n
c o
m p
a r ed w it
h
e a ch
s am p l
et
ak
e nf
r om
t
h
at
w
ell
T h i
s stu
d
y
d i d
n ot t
ry
t
o s ep
a r at
et
h
et
em
p
o r al
c om p
o
n e nt
of
v a ria
t
io n
fr
om
al l
ot
h
e rf
a ct
o r st
h
at
aff
e ct
s am p l
e r e s ult
sT
h
e s em
ay
h
a v ei
n clu
d
ed
t
i m
e of
y
e a r,t
i m
e of d
ay
,w
at
e ru
t
i l i
z at
i
o n(
eg
,1
-d
a
y
,3
-d
a
y
, o r1
-