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Normal Fluoride Concentrations in Spot Samples of Urine
H. Tsunoda and M.-H. Yu (Editors) Fluoride Research 1985, Studies in Environmental Science, Volume 27, pp. 401-406 0 1986 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
401
NORMAL FLUORIDE CONCENTRATIONS I N SPOT SAMPLES OF U R I N E
KAORU KASAHARA, TAKESHI KONDO. AND TAKASHI NAKANE D e p a r t m e n t o f Communi t y D e n t i s t r y , Gobara S h i o j i r i C i t y 399-07, J a p a n
Matsumoto Dental College,
1780 Hirooka
ABSTRACT I n an a t t e m p t t o e v a l u a t e n o r m a l f l u o r i d e c o n c e n t r a t i o n s i n u r i n e , s a m p l e s o f u r i n e w e r e c o l l e c t e d f r o m 1,213
spot
h e a l t h y Japanese m a l e a d u l t s ,
c o n s i d e r e d t o be f r e e f r o m u n u s u a l f l u o r i d e exposure i n t h e i r l i v i n g o r working environment, Mid-morning
and t h e i r f l u o r i d e c o n t e n t s
were determined.
u r i n e s a m p l e s w e r e c o l l e c t e d f r o m 1,047 G r o u n d S e l f - D e f e n s e
F o r c e o f f i c i a l s aged 1 8 t o 58, and t h e f i r s t - m o r n i n g u r i n e s a m p l e s f r o m 172 f a r m e r s aged 50 t o 69.
F l u o r i d e c o n c e n t r a t i o n s w e r e d e t e r m i n e d u s i n g a n F-
e l e c t r o d e a f t e r t h e f l u o r i d e was s e p a r a t e d b y a m i c r o d i f f u s i o n method. S t a t i s t i c a l a n a l y s i s o f t h e d a t a was c a r r i e d o u t f o l l o w i n g l o g a r i t h m i c t r a n s f o r m a t i o n o f t h e values,
since t h e d i s t r i b u t i o n o f f l u o r i d e concentra-
t i o n s was n e a r l y l o g a r i t h m i c a l l y n o r m a l . G e o m e t r i c mean v a l u e s o f t h e u r i n a r y f l u o r i d e c o n c 2 n t r a t i o n s o f t h e S e l f D e f e n s e F o r c e o f f i c i a l s (N=1040) and t h e f a r m e r s (N=164) w e r e e s t i m a t e d t o b e 0.32 m g / l
a n d 0.50 m g / l ,
respectively.
INTRODUCTION U r i n a r y e x c r e t i o n o f f l u o r i d e i s w i d e l y a c c e p t e d as one o f t h e b e s t i n d i c e s o f f l u o r i d e a b s o r p t i o n (1).
F l u o r i d e l e v e l s i n t h e u r i n e samples
o f i n d u s t r i a l w o r k e r s e x p o s e d t o f l u o r i d e have, i n d e x o f h e a l t h c a r e (2.3). tion,
24-hour
therefore,
b e e n u s e d a s an
F o r an a c c u r a t e e v a l u a t i o n o f f l u o r i d e e x c r e -
u r i n e s a m p l e s s h o u l d be used.
However,
s p o t samples o f u r i n e
a r e employed r o u t i n e l y . Normal f l u o r i d e e x c r e t i o n i n t h e 24-hour j e c t s has been r e p o r t e d b y Tsunoda
u r i n e s a m p l e s o f J a p a n e s e sub-
g d.( 3 ) ,
b u t r e p o r t s on t h e normal
f l u o r i d e c o n c e n t r a t i o n o f s p o t samples o f u r i n e have been c o n t r a d i c t o r y . I n an a t t e m p t t o e v a l u a t e normal f l u o r i d e c o n c e n t r a t i o n s i n urine.' s a m p l e s w e r e c o l l e c t e d f o r m 1,219
spot
h e a l t h y Japanese male a d u l t s c o n s i d e r e d
t o be f r e e f r o m f l u o r i d e exposure i n t h e i r l i v i n g o r w o r k i n g environment, and t h e f l u o r i d e c o n c e n t r a t i o n s o f t h e s e u r i n a r y samples were determined.
402 MATERIALS AND METHODS I n t h i s s t u d y , t w o d i f f e r e n t e x p e r i m e n t a l g r o u p s w e r e examined. m o r n i n g u r i n e s a m p l e s (8:30-11:OO Self-Defense Force
a.m.)
(GSDF) o f f i c i a l s
Mid-
w e r e c o l l e c t e d f r o m 1,047 G r o u n d
aged 18 t o 58, and t h e f i r s t - m o r n i n g
u r i n e samples were c o l l e c t e d f r o m 172 farmers,
aged 50 t o 69.
residing i n
d i f f e r e n t areas. F l u o r i d e c o n c e n t r a t i o n s i n t h e d r i n k i n g w a t e r i n b o t h areas were l e s s t h a n 0.1 m g / l and f l u o r i d e i n t h e a i r was n o t d e t e c t a b l e .
To s e p a r a t e t h e f l u o r i n e i n u r i n e ,
(4).
a m i c r o d i f f u s i o n method was employed
A 5 m l u r i n e s a m p l e was d i f f u s e d i n 2.7 M HC104 ( H M D S - s a t u r a t e d ) .
F l u o r i n e was t r a p p e d i n f i l t e r paper t r e a t e d w i t h 0.5
M
NaOH.
The f i l t e r
paper was t h e n p l a c e d i n a t e s t t u b e c o n t a i n i n g 1 m l o f d i s t i l l e d w a t e r and t h e f l u o r i d e was e l u t e d by shaking.
F l u o r i d e concentrations i n the eluates
w e r e m e a s u r e d b y t h e f l u o r i d e i o n - s c l ? c C i v a 31.?c-:r>:.'? . i n l i i ~ o d . F i g u r e 1
shc'~.i; .i:is ~ . : i ; x ~ r o t :? IiZsY ! f a r ,Tic;po?i f-F:!-io?.
F i g u r e 1.
Apparatus used f o r m i c r o d i f f u s i o n .
RESULTS The minimum and maximum f l u o r i d e c o n c e n t r a t i o n s i n t h e mid-morning u r i n e s a m p l e s w e r e f o u n d t o b e 0.046 m g / l and 4.6 m g / l . m o r n i n g u r i n e were 0.070 mg/l and 10 mg/l.
and t h o s e i n t h e f i r s t -
respectively.
m o r n i n g u r i n e s a m p l e s showed m o r e t h a n 1.2 m g F / l .
Seven o f t h e mid-
and n i n e o f t h e f i r s t -
m o r n i n g u r i n e s a m p l e s g a v e v a l u e s h i g h e r t h a n 1.4 m g F / l .
They w e r e ex-
c l u d e d f r o m t h e s t a t i s t i c a l a n a l y s i s , as t h e y were c o n s i d e r e d abnormal. F i g u r e s 2 a n d 3 show t h e h i s t o g r a m s o f f l u o r i d e c o n c e n t r a t i o n s i n t h e mid-morning
and t h e f i r s t - m o r n i n g
urine.
These r e s u l t s suggest t h a t t h e
d i s t r i b u t i o n o f u r i n a r y f l u o r i d e c o n c e n t r a t i o n s i n s p o t samples i s logar i t h m i c a l l y normal.
ik
400
300
200
403
20
1
100
0
0 .24
0
.48
.72
1.2
.96
0
.4
.8
1.2
1.6
F conc. i n u r i n e (mgll)
F conc. i n u r i n e ( m g / l )
F i g u r e 2. (N=l040).
Hi,-togram
o f fluoride concentrations i n t h e mid-morning
urine
F i g u r e 3. (N=l64).
Histogram o f f l u o r i d e concentrations i n the f i r s t - m o r n i n g
urine
(21 99 r
0.05
0.1
0.5
1
5
F concentrotlons In urlne Img/l)
F i g u r e 4. C u m u l a t i v e f r e q u e n c y c u r v e o f f l u o r i d e concentrations i n spot sampling urine. 0 . mid-morning u r i n e ; O , f i r s t - m o r n i n g u r i n e .
404 F i g u r e 4 shows t h e c u m u l a t i v e f r e q u e n c y c u r v e o f u r i n a r y f l u o r i d e concent r a t i o n s on l o g a r i t h m i c p r o b a b i l i t y paper.
The d i s t r i b u t i o n of u r i n a r y
f l u o r i d e c o n c e n t r a t i o n s was c o n f i r m e d t o b e l o g a r i t h m i c a l l y n o r m a l , t h e c u m u l a t i v e f r e q u e n c y gave e s s e n t i a l l y s t r a i g h t l i n e s .
since
Thus s t a t i s t i c a l
a n a l y s i s o f t h e d a t a was p e r f o r m e d a f t e r t h e l o g a r i t h m i c t r a n s f o r m a t i o n of the values. T a b l e s I and I 1 show t h e g e o m e t r i c mean v a l u e s and s t a n d a r d d e v i a t i o n of u r i n a r y f l u o r i d e c o n c e n t r a t i o n s o f s p o t samples.
The g e o m e t r i c mean v a l u e s
o f t h e f l u o r i d e c o n c e n t r a t i o n s i n t h e mid-morning and t h e f i r s t - m o r n i n g u r i n e s a m p l e s w e r e c a l c u l a t e d t o be 0.32 m g / l and 0.50 m g / l , F i g u r e 5 i l l u s t r a t e s t h e n o r m a l r a n g e (Meang
* 2S.D. 4 ) o f
r i d e c o n c e n t r a t i o n s i n d i f f e r e n t age groups.
TABLE I FLUORIDE CONCENTRATIONS ( m g / l ) I N THE M I D - M O R N I N G U R I N E OF MALE ADULTS Age
n
Geometric S. D. Mean
18-1 9
97
0.25
1.57
20-29
447
0.29
1.72
30-39
182
0.36
1.73
40-49
209
0.35
1.60
50-58
105
0.37
1.66
Total
1040
0.32
1.71
TABLE I 1 FLUORIDE CONCENTRATIONS (mg/l) I N THE FIRST-MORNING U R I N E OF MALE ADULTS
n
Geometric Mean S. D.
50-59
a3
0.49
1.65
60-69
81
0.50
1.57
Total
164
0.50
1.61
respectively. urinary fluo-
405
ll
T
T
10’
30’ 40’
20’
50’
60’s
Age group
F i g u r e 5. N o r m a l r a n g e (Mean + 2S.D. ) o f u r i n a r y f l u o r i d e c o n c e n t r a t i o n s i n d i f f e r e n t age groups. , a i d - m o r n g n g ; 0 ,f i r s t - m o r n i n g u r i n e .
DISCUSSION F l u o r i d e c o n c e n t r a t l o n s i n u r i n e samples a r e o f t e n d i r e c t l y determined using a fluoride ion-selective i s e a s y t o use,
e l e c t r o d e p o t e n t i a l i s long,
5).
electrode.
The d i r e c t d e t e r n i n a t i o n m e t h o d
b u t t h e t i m e r e q u i r e d t o r e a c h an e q u i l i b r i u m o f t h e e s p e c i a l l y a t l o w f l u o r i d e c o n c e n t r a t i o n s (2,
I n t h i s s t u d y . f l u o r i n e was s e p a r a t e d f r o m u r i n e s a m p l e s b y m i c r o -
d i f f u s i o n method,
and i t s c o n c e n t r a t i o n d e t e r m i n e d as a s a m p l e f i v e t i m e s
i t s o r i g i n a l concentration.
With t h i s method,
t h e e l e c t r o d e p o t e n t i a l can
be s t a b i l i z e d i n a few minutes.
I n s t a t i s t i c a l analysis o f u r i n a r y f l u o r i d e concentrations,
t h e concent-
r a t i o n s a r e o f t e n r e g a r d e d a s n o r m a l d i s t r i b u t i o n (2.5-7,9).
We h a v e
confirmed that the distribution o f urinary fluoride concentrations i s l o g a r i t h m i c a l l y normal,
as was s u g g e s t e d b y T o y o t a (8).
Thus,
t h e geomet-
r i c mean s h o u l d b e u s e d i n s t e a d o f t h e a r i t h m e t r i c mean f o r t h e s t a t i s t i c a l analysis. T h e r e h a v e b e e n many r e p o r t s c o n c e r n i n g t h e n o r m a l f l u o r i d e c o n c e n t r a t i o n s o f s p o t samples o f u r i n e u r i n e , 0.32 m g / l ,
(2,5-9).
The mean v a l u e o f m i d - m o r n i n g
o b t a i n e d i n t h i s study i s l o w e r than those r e p o r t e d by
o t h e r w o r k e r s (5-7).
T h i s d i s c r e p a n c y may b e d u e p a r t l y t o t h e u s e o f
g e o m e t r i c means i n s t a t i s t i c a l a n a l y s i s and t o t h e u n i q u e l i f e - s t y l e o f t h e p a r t i c i p a t i n g GSDF o f f i c i a l s . A k i n i v i a r e p o r t e d t h e mean f l u o r i d e c o n c e n t r a t i o n o f t h e f i r s t - m o r n i n g u r i n e t o be 0.457 m g / l ( 9 ) . O u r d a t a w e r e s i m i l a r t o t h i s value, s t a n d a r d d e v i a t i o n was v e r y l a r g e .
but the
A possible explanation i s t h a t eating
h a b i t s and l i f e - s t y l e s may h a v e i n f l u e n c e d f l u o r i d e e x c r e t i o n . .
406
CONCLUSION S t u d i e s were made on t h e normal f l u o r i d e c o n c e n t r a t i o n s o f s p o t samples o f u r i n e among Japanese male s u b j e c t s . The d i s t r i b u t i o n o f f l u o r i d e concent r a t i o n s i n s p o t samples was n e a r l y l o g a r i t h m i c a l l y normal.
The g e o m e t r i c
mean f l u o r i d e c o n c e n t r a t i o n o f t h e mid-morning u r i n e samples o b t a i n e d from 1,040 Ground Self-Defense F o r c e o f f i c i a l s was 0.32 mg/l,
while the f i r s t -
m o r n i n g u r i n e samples c o l l e c t e d f r o m 164 f a r m e r s gave a v a l u e o f 0.50 mg/l.
REFERENCES
1.
I s h i k a w a S (1976) J I w a t e Med Ass 28:207-222
2. Y o s h i d a Y, T o y o t a S , Kono K, Watanabe M, I w a s a k i K ( 1 9 7 8 ) B u l l Osaka Med School 24:56-67
3.
Tsunoda H, S a k u r a i S , I t a i K, (1984) F l u o r i d e 17: 159-167 Kondo T (1978)
S a t o T,
Nakaya S,
M i t a M,
Tatsumi
4.
K a m i j o h K,
5.
Yasaki T, Ohhashi K, Dent H l t h 24:191-206
6.
Seki Y.
7.
K o n i s h i M, I w a t a M. Minagawa Y (1975) Jap J I n d H e a l t h 17:238-239
a.
Toyota S (1979) Jap J I n d H e a l t h 21:335-348
9.
A k i n i w a K (1981)
M
Matsumoto Shigaku 4:150-153
Kubota M,
Okudera H.
M i y a s i t a N,
I i z u k a Y (1974) J
I c h i k a w a Y (1975) Jap J I n d H e a l t h 17:236-237
F l u o r i d e R 1:75-77
401
NORMAL FLUORIDE CONCENTRATIONS I N SPOT SAMPLES OF U R I N E
KAORU KASAHARA, TAKESHI KONDO. AND TAKASHI NAKANE D e p a r t m e n t o f Communi t y D e n t i s t r y , Gobara S h i o j i r i C i t y 399-07, J a p a n
Matsumoto Dental College,
1780 Hirooka
ABSTRACT I n an a t t e m p t t o e v a l u a t e n o r m a l f l u o r i d e c o n c e n t r a t i o n s i n u r i n e , s a m p l e s o f u r i n e w e r e c o l l e c t e d f r o m 1,213
spot
h e a l t h y Japanese m a l e a d u l t s ,
c o n s i d e r e d t o be f r e e f r o m u n u s u a l f l u o r i d e exposure i n t h e i r l i v i n g o r working environment, Mid-morning
and t h e i r f l u o r i d e c o n t e n t s
were determined.
u r i n e s a m p l e s w e r e c o l l e c t e d f r o m 1,047 G r o u n d S e l f - D e f e n s e
F o r c e o f f i c i a l s aged 1 8 t o 58, and t h e f i r s t - m o r n i n g u r i n e s a m p l e s f r o m 172 f a r m e r s aged 50 t o 69.
F l u o r i d e c o n c e n t r a t i o n s w e r e d e t e r m i n e d u s i n g a n F-
e l e c t r o d e a f t e r t h e f l u o r i d e was s e p a r a t e d b y a m i c r o d i f f u s i o n method. S t a t i s t i c a l a n a l y s i s o f t h e d a t a was c a r r i e d o u t f o l l o w i n g l o g a r i t h m i c t r a n s f o r m a t i o n o f t h e values,
since t h e d i s t r i b u t i o n o f f l u o r i d e concentra-
t i o n s was n e a r l y l o g a r i t h m i c a l l y n o r m a l . G e o m e t r i c mean v a l u e s o f t h e u r i n a r y f l u o r i d e c o n c 2 n t r a t i o n s o f t h e S e l f D e f e n s e F o r c e o f f i c i a l s (N=1040) and t h e f a r m e r s (N=164) w e r e e s t i m a t e d t o b e 0.32 m g / l
a n d 0.50 m g / l ,
respectively.
INTRODUCTION U r i n a r y e x c r e t i o n o f f l u o r i d e i s w i d e l y a c c e p t e d as one o f t h e b e s t i n d i c e s o f f l u o r i d e a b s o r p t i o n (1).
F l u o r i d e l e v e l s i n t h e u r i n e samples
o f i n d u s t r i a l w o r k e r s e x p o s e d t o f l u o r i d e have, i n d e x o f h e a l t h c a r e (2.3). tion,
24-hour
therefore,
b e e n u s e d a s an
F o r an a c c u r a t e e v a l u a t i o n o f f l u o r i d e e x c r e -
u r i n e s a m p l e s s h o u l d be used.
However,
s p o t samples o f u r i n e
a r e employed r o u t i n e l y . Normal f l u o r i d e e x c r e t i o n i n t h e 24-hour j e c t s has been r e p o r t e d b y Tsunoda
u r i n e s a m p l e s o f J a p a n e s e sub-
g d.( 3 ) ,
b u t r e p o r t s on t h e normal
f l u o r i d e c o n c e n t r a t i o n o f s p o t samples o f u r i n e have been c o n t r a d i c t o r y . I n an a t t e m p t t o e v a l u a t e normal f l u o r i d e c o n c e n t r a t i o n s i n urine.' s a m p l e s w e r e c o l l e c t e d f o r m 1,219
spot
h e a l t h y Japanese male a d u l t s c o n s i d e r e d
t o be f r e e f r o m f l u o r i d e exposure i n t h e i r l i v i n g o r w o r k i n g environment, and t h e f l u o r i d e c o n c e n t r a t i o n s o f t h e s e u r i n a r y samples were determined.
402 MATERIALS AND METHODS I n t h i s s t u d y , t w o d i f f e r e n t e x p e r i m e n t a l g r o u p s w e r e examined. m o r n i n g u r i n e s a m p l e s (8:30-11:OO Self-Defense Force
a.m.)
(GSDF) o f f i c i a l s
Mid-
w e r e c o l l e c t e d f r o m 1,047 G r o u n d
aged 18 t o 58, and t h e f i r s t - m o r n i n g
u r i n e samples were c o l l e c t e d f r o m 172 farmers,
aged 50 t o 69.
residing i n
d i f f e r e n t areas. F l u o r i d e c o n c e n t r a t i o n s i n t h e d r i n k i n g w a t e r i n b o t h areas were l e s s t h a n 0.1 m g / l and f l u o r i d e i n t h e a i r was n o t d e t e c t a b l e .
To s e p a r a t e t h e f l u o r i n e i n u r i n e ,
(4).
a m i c r o d i f f u s i o n method was employed
A 5 m l u r i n e s a m p l e was d i f f u s e d i n 2.7 M HC104 ( H M D S - s a t u r a t e d ) .
F l u o r i n e was t r a p p e d i n f i l t e r paper t r e a t e d w i t h 0.5
M
NaOH.
The f i l t e r
paper was t h e n p l a c e d i n a t e s t t u b e c o n t a i n i n g 1 m l o f d i s t i l l e d w a t e r and t h e f l u o r i d e was e l u t e d by shaking.
F l u o r i d e concentrations i n the eluates
w e r e m e a s u r e d b y t h e f l u o r i d e i o n - s c l ? c C i v a 31.?c-:r>:.'? . i n l i i ~ o d . F i g u r e 1
shc'~.i; .i:is ~ . : i ; x ~ r o t :? IiZsY ! f a r ,Tic;po?i f-F:!-io?.
F i g u r e 1.
Apparatus used f o r m i c r o d i f f u s i o n .
RESULTS The minimum and maximum f l u o r i d e c o n c e n t r a t i o n s i n t h e mid-morning u r i n e s a m p l e s w e r e f o u n d t o b e 0.046 m g / l and 4.6 m g / l . m o r n i n g u r i n e were 0.070 mg/l and 10 mg/l.
and t h o s e i n t h e f i r s t -
respectively.
m o r n i n g u r i n e s a m p l e s showed m o r e t h a n 1.2 m g F / l .
Seven o f t h e mid-
and n i n e o f t h e f i r s t -
m o r n i n g u r i n e s a m p l e s g a v e v a l u e s h i g h e r t h a n 1.4 m g F / l .
They w e r e ex-
c l u d e d f r o m t h e s t a t i s t i c a l a n a l y s i s , as t h e y were c o n s i d e r e d abnormal. F i g u r e s 2 a n d 3 show t h e h i s t o g r a m s o f f l u o r i d e c o n c e n t r a t i o n s i n t h e mid-morning
and t h e f i r s t - m o r n i n g
urine.
These r e s u l t s suggest t h a t t h e
d i s t r i b u t i o n o f u r i n a r y f l u o r i d e c o n c e n t r a t i o n s i n s p o t samples i s logar i t h m i c a l l y normal.
ik
400
300
200
403
20
1
100
0
0 .24
0
.48
.72
1.2
.96
0
.4
.8
1.2
1.6
F conc. i n u r i n e (mgll)
F conc. i n u r i n e ( m g / l )
F i g u r e 2. (N=l040).
Hi,-togram
o f fluoride concentrations i n t h e mid-morning
urine
F i g u r e 3. (N=l64).
Histogram o f f l u o r i d e concentrations i n the f i r s t - m o r n i n g
urine
(21 99 r
0.05
0.1
0.5
1
5
F concentrotlons In urlne Img/l)
F i g u r e 4. C u m u l a t i v e f r e q u e n c y c u r v e o f f l u o r i d e concentrations i n spot sampling urine. 0 . mid-morning u r i n e ; O , f i r s t - m o r n i n g u r i n e .
404 F i g u r e 4 shows t h e c u m u l a t i v e f r e q u e n c y c u r v e o f u r i n a r y f l u o r i d e concent r a t i o n s on l o g a r i t h m i c p r o b a b i l i t y paper.
The d i s t r i b u t i o n of u r i n a r y
f l u o r i d e c o n c e n t r a t i o n s was c o n f i r m e d t o b e l o g a r i t h m i c a l l y n o r m a l , t h e c u m u l a t i v e f r e q u e n c y gave e s s e n t i a l l y s t r a i g h t l i n e s .
since
Thus s t a t i s t i c a l
a n a l y s i s o f t h e d a t a was p e r f o r m e d a f t e r t h e l o g a r i t h m i c t r a n s f o r m a t i o n of the values. T a b l e s I and I 1 show t h e g e o m e t r i c mean v a l u e s and s t a n d a r d d e v i a t i o n of u r i n a r y f l u o r i d e c o n c e n t r a t i o n s o f s p o t samples.
The g e o m e t r i c mean v a l u e s
o f t h e f l u o r i d e c o n c e n t r a t i o n s i n t h e mid-morning and t h e f i r s t - m o r n i n g u r i n e s a m p l e s w e r e c a l c u l a t e d t o be 0.32 m g / l and 0.50 m g / l , F i g u r e 5 i l l u s t r a t e s t h e n o r m a l r a n g e (Meang
* 2S.D. 4 ) o f
r i d e c o n c e n t r a t i o n s i n d i f f e r e n t age groups.
TABLE I FLUORIDE CONCENTRATIONS ( m g / l ) I N THE M I D - M O R N I N G U R I N E OF MALE ADULTS Age
n
Geometric S. D. Mean
18-1 9
97
0.25
1.57
20-29
447
0.29
1.72
30-39
182
0.36
1.73
40-49
209
0.35
1.60
50-58
105
0.37
1.66
Total
1040
0.32
1.71
TABLE I 1 FLUORIDE CONCENTRATIONS (mg/l) I N THE FIRST-MORNING U R I N E OF MALE ADULTS
n
Geometric Mean S. D.
50-59
a3
0.49
1.65
60-69
81
0.50
1.57
Total
164
0.50
1.61
respectively. urinary fluo-
405
ll
T
T
10’
30’ 40’
20’
50’
60’s
Age group
F i g u r e 5. N o r m a l r a n g e (Mean + 2S.D. ) o f u r i n a r y f l u o r i d e c o n c e n t r a t i o n s i n d i f f e r e n t age groups. , a i d - m o r n g n g ; 0 ,f i r s t - m o r n i n g u r i n e .
DISCUSSION F l u o r i d e c o n c e n t r a t l o n s i n u r i n e samples a r e o f t e n d i r e c t l y determined using a fluoride ion-selective i s e a s y t o use,
e l e c t r o d e p o t e n t i a l i s long,
5).
electrode.
The d i r e c t d e t e r n i n a t i o n m e t h o d
b u t t h e t i m e r e q u i r e d t o r e a c h an e q u i l i b r i u m o f t h e e s p e c i a l l y a t l o w f l u o r i d e c o n c e n t r a t i o n s (2,
I n t h i s s t u d y . f l u o r i n e was s e p a r a t e d f r o m u r i n e s a m p l e s b y m i c r o -
d i f f u s i o n method,
and i t s c o n c e n t r a t i o n d e t e r m i n e d as a s a m p l e f i v e t i m e s
i t s o r i g i n a l concentration.
With t h i s method,
t h e e l e c t r o d e p o t e n t i a l can
be s t a b i l i z e d i n a few minutes.
I n s t a t i s t i c a l analysis o f u r i n a r y f l u o r i d e concentrations,
t h e concent-
r a t i o n s a r e o f t e n r e g a r d e d a s n o r m a l d i s t r i b u t i o n (2.5-7,9).
We h a v e
confirmed that the distribution o f urinary fluoride concentrations i s l o g a r i t h m i c a l l y normal,
as was s u g g e s t e d b y T o y o t a (8).
Thus,
t h e geomet-
r i c mean s h o u l d b e u s e d i n s t e a d o f t h e a r i t h m e t r i c mean f o r t h e s t a t i s t i c a l analysis. T h e r e h a v e b e e n many r e p o r t s c o n c e r n i n g t h e n o r m a l f l u o r i d e c o n c e n t r a t i o n s o f s p o t samples o f u r i n e u r i n e , 0.32 m g / l ,
(2,5-9).
The mean v a l u e o f m i d - m o r n i n g
o b t a i n e d i n t h i s study i s l o w e r than those r e p o r t e d by
o t h e r w o r k e r s (5-7).
T h i s d i s c r e p a n c y may b e d u e p a r t l y t o t h e u s e o f
g e o m e t r i c means i n s t a t i s t i c a l a n a l y s i s and t o t h e u n i q u e l i f e - s t y l e o f t h e p a r t i c i p a t i n g GSDF o f f i c i a l s . A k i n i v i a r e p o r t e d t h e mean f l u o r i d e c o n c e n t r a t i o n o f t h e f i r s t - m o r n i n g u r i n e t o be 0.457 m g / l ( 9 ) . O u r d a t a w e r e s i m i l a r t o t h i s value, s t a n d a r d d e v i a t i o n was v e r y l a r g e .
but the
A possible explanation i s t h a t eating
h a b i t s and l i f e - s t y l e s may h a v e i n f l u e n c e d f l u o r i d e e x c r e t i o n . .
406
CONCLUSION S t u d i e s were made on t h e normal f l u o r i d e c o n c e n t r a t i o n s o f s p o t samples o f u r i n e among Japanese male s u b j e c t s . The d i s t r i b u t i o n o f f l u o r i d e concent r a t i o n s i n s p o t samples was n e a r l y l o g a r i t h m i c a l l y normal.
The g e o m e t r i c
mean f l u o r i d e c o n c e n t r a t i o n o f t h e mid-morning u r i n e samples o b t a i n e d from 1,040 Ground Self-Defense F o r c e o f f i c i a l s was 0.32 mg/l,
while the f i r s t -
m o r n i n g u r i n e samples c o l l e c t e d f r o m 164 f a r m e r s gave a v a l u e o f 0.50 mg/l.
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