45
£ RESULTS AND DISCUSSION
TABLE 18.
The concentrations of lead in the various specimens
Rib
in units of #g/g bone ash, along with the age of the
§ <ubject are presented in Table 18. The specimens are
b
lead, that?
: lead int
of about.
vention of?
ingested;
Il within!
nee stud-¢
tabulated by bone type, 1e., rib, vertebra and cortical
(femur and tibia), and by sex from subjects without
known bone disease (“normal” bone). In addition, data
from a previously published paperare included for uninvolved cortical bone (femur or tibia) from subjects
with osteogenic sarcomas (“sarcoma” bone).
The concentration is plotted as a function of age of
ge PR oR ite
the subject in Figure 39. The linear least squares line
diological _ jx shown for each group. For the “normal” cases the
n dietary?
equation 1s
Smoking, ?
> skeletal |
with age”
ear half-
and for the “sarcoma” cases
Y = (86 = 2.7) + (0.37 + 0.08)E,
2 ad
, a natu-;
Y = (3.6 = 43) + (0.60 + 0.09)¢
API
their en-; where Y is the lead concentration (vg/g ash) and ¢ jis
a: aie a,
Le
uy
we
the age in years.
The variation of the lead content of different bones
the lead |
with
age was evaluated and the coefficients of the linear
’ persons
Joast
squares fits to the data are summarized in Table
re avail- :
19.
The
linear fit was chosen as the simplest to describe
able for’
the data; no significant improvement of the variance
wus given by a second order function (P > 0.05) ,°®
except in “normal” female vertebra (P < 0.05).
The zero intercepts, A, (concentration at birth)
nal surrunged from —2 to 13 yg/g ash with large standard
are from
deviations. At the 5% levels of significance or better,
asis for, only 2 groups, sarcoma “all” and sarcoma “female,”
ve been ; had intercepts significantly greater than zero (P <
' 0.01). However, a mean value of 8.7 ng/g ash was ob-
n teeth, tained for bone from three stillbirths and a 6-month-old
‘hboring * child. This is consistent with the data of Horiuchi et
a 8 age
al.'*) who found the lead concentration of fetal bone to
increase with age from 0.5 ug/g (3 wg/g ash if the wet-
by the i to-ash ratio in fetal bone is 6) in a 5-month fetus to
(13)
In (
Lopg/g (9 ug/g ash) at 10 months. Schroeder and
ind disTipton (their Table 5)™ foundless than 4 ng/g ash in
to O.2¢ 1 hone in their 0-to-l-year old subjects (apparently the
: to redetcetion limits of their measurements). The appar1 is decntly negative intercept in the normal cortical bone is
igth of ¢ consistent with that of Horiuchi et al.‘®) for femur
al wet- hone,
heating ;
The slopes of the regression curves of the various
of the { data groups are significantly greater than zero (P <
re, and 3 0.01), except for female rib (P ~ 0.07). The slopes of
ith the *
2 given é
overall }
?
OQ.
‘he lines for the different groups are not significantly
‘ilerent from that of the total “normal” of 0.60 pe
(< ash)—1 yr-1!, except those of the female rib and
“s:reoma” subjects which are significantly lower (P <
Concentration oF LEAD IN BONE ASH AS
A FUuNcTion OF AGE OF SUBJECT
Age,
yt
Male
0
3
8
27
30
32°
36
Concentration,
jug Pb/g}
ash
16.9
<1.0
3.6
93.2
11.0
15.4
13.2
37
37
19.5
25.5
37
39,4
38
38
41
42
44
48
59
68
74
Female
Vertebra
Age,
yr
jug Pb/g)
0.5
28°
28
44
53
57
8.5
24.7
35.5
19.4
61.2
47.9
59
71
ash
41.9
41.6
19.7
7.7
59.4
57.2
50.8
25.8
49.6
48.1
21.7
8
18
25
32
7.2
0
9.7
0
15.0
9
16.6 | 34
34.
35
87.
38
40
41
42
43
«13.2
8.4
s«13.5
| 21.6
| 17.9
22.5
24.1
13.0 ,
49
65
68
16.5
13.4
25.6
32) 25.7
46
Concentration,
46
BS
65
65
85
85
6.0
3.5
12.2
28.8
Cortical
Concentration
Age,
yr
[ug Pb/g|
8
13
14
19
20
42
Age,
Concentration
yr
|ug Pb/g
3.9
3.3
12.6
2.8
4.0
38.9
9
12
13
13
16
17
7.0
3.5
7.3
7.5
7.6
30.5
49
53
24.0
34.5
23
27
17.7
13.7
56
43.5
32
16.3
ash
48
37.2
59
61
65
66
72
85
79.3
31.5
96.5
30.8
43.3
40.5
13
61
72
6.2
22.2
| 33.8
44.8
67.2
65.2
82.5
60.5
18.3
Cortical
17
56.9
13.0
44
47
58
59
63
64
67
68 |
17.3
31.8
50.0
38.6
19.0
33.9
28.2
33.4
7
11
12
12
22.5
3.6
14.7
18.1
15
15
15
23.
30
46
47
50
24.7
16.9
16.4
24.0
19.6
25.9
10.1
22.0
14
|
'
ash
62
14.7
40.0
‘) Subjects having no known bonedisease.
) Subjects having osteogenic sarcoma,
0.01 and < 0.025, respectively). However, these differ-
ences appear to result from an excess of high values at
the younger ages. If the zero intercept, A, is fixed at
zero, the slopes of the regression lines are no longer
significantly different.
That the slopes are not zero is also shown by the
significant correlation coefficients in Table 19 of about
0.5 to 0.7, While bone from female rib increases at only
about one-half the rate of male rib, this difference is
not significant (P ~ 0.10). The slope for “normal”
male cortical bone appears to be different from that