Uncontrolled Paths
Sweat 6-4 I.4 4 .0 (4 .0)’ Ca, I’: (Reference 1, Appendix C)
fSr\
Sr:
(
---)
XCa lOsSXOR,S.,,t/))l,,,\ Ca / pool
(Reference 4, Appendix C)
Sali_it 6.’2 19.3 2.4 (‘1.6) Ca, I’: 100 ml/day estimated
byauthorsXcon-centration in adult saliva
(Re-ference 3, Appendix C)
fSr\
Sr:
(
-- J XCa lossIinperfect Collection
Urine 1 .4 7.7 4.4 (3.4) Ca, P. Sr: 5% loss of urine reported by mothers
inherent Losses
Itittke .5.0 6.1 (6.6) Ca, P, Sr: 1% of intake not ingested; estimated
I)y authors
Feres !.i9 I .8 4.3 (5(1) Ca, I’, Sr: 1% of excreta not collected;
esti-mated by authors
I ru’e 0 .‘3 1.5 (1.9 (0 .7) Ca, P. Sr: 1% of excreta not collected ;
esti-I mated by authors
‘I’otitlt !2! 36 2’2 (‘2)
a“trofltilllll losses II, parentheses are for infants 26 to 37; other losses were computed froni strontium excretion
alties (Ierive(l in Part 3---Strontiuni M odel as Function of Age for All 30 Infants.
t Subtract this total froiti gross retention to obtain corrected retention.
743
APPENDIX
C
EVALUATION
OF
SYSTEMATIC
ERRORS
UNCONTROLLED EXCRETORY PATHS
E
STIMATES of the order of magnitude ofcalcium and phosphorus losses by un-controlled paths
(
see Part 1-Accuracy)
in-(licated that only sweating and drooling
were significant. No commonly accepted
values are available for losses by either of
these paths, probably because the daily
amounts are small and extremely variable.
The daily amounts of calcium and phos-1)hOrus in sweat listed in Table XXXII are
the averages from 14 infants between the
ages of 14 and 196 days who consumed cows’ milk.1 The range of reported values is large, as expected for a function that de-pends on so many factors. A fraction of the amount attributed to sweat may be desqua-mation of the skin.2 The study cited was the
only one found in the literature that
per-tamed to infants.
Neither the average amount of saliva lost
by infants between meals nor its calcium and phosphorus concentrations are known.
‘FABLE XXXII
ESTIMATE OF AVERAGE SYSTIIMATIC LossEs OF CALCIUM, PIIOSPHORUS, AND STRONTIUM
DURING METABOLIC BALANCR STUDY
(‘a P Sr
I5alh BaIn8 for Jalises
-TABLE XXXIII
ESTIMATE OF STRorrrIims-90 CORRECTIONS’
Data -- -____________________All Periods inhalation Systematic
Losses
f
Periods with Separated
Urine and Feces
PerioSs with Stable Strontium Balances
Inhalation Systematic
Losses SystematicLo8ses Inhalation
Uncontrolled Pat/ia
Sweat and saliva 0.OOt 0.07t O.10
Imperfect Collection
Urine 0.03 0.03 0.05
Inherent Losses
Ingestion
Absorption through lung
Feces
Urine
0.06
0.05 0.01
0.04
0 .01
0.07
0.05 0.01
0.06
0.03
0.11
0.08 0.01
0.08
0.04
Retention -0.1 +0.05 -0.23 +0.09 -0.35 +0.1
Total -0.16 -0.14 -0.3
* In picocuries per day.
I
‘#{176}Srloss\
/
9#{176}Srlossti
J
=1
-\
“'Sr urine/these periods\
“Sr urine Infants 26 to 37. /9#{176}Sr\9#{176}Srloss = systematic Sr loss x(
J
from Figure 28.\
Sr /urine§ Estimates of 9#{176}Srin feces and urine from Equations 4-la and 4-4a.
The values in Table XXXII are based on
the assumption that 100 ml saliva is lost daily between meals and that the calcium and phosphorus concentrations are those in
adults’ saliva.3
Daily losses of strontium in sweat and saliva were computed from the prod-uct of the daily calcium losses, the stron-hum/calcium ratio in the exchangeable pool
(
Figure 21),
and the respective0 Rsweatipiasn,a and ORendogenous/piasma. The
ORaweatipiasma was taken to be 1.5, the aver-age value for three adults given intra-venous infusions of stable strontium.4 An
ORendocenous/plasma of unity5 was used. Average losses of strontium-90 in sweat and saliva
(
Table XXXIII)
were assumedto be in the same proportion relative to the
exchangeable pool as losses of stable
stron-tium, in view of their identical chemical
be-havior. As explained, the specific activity in the exchangeable pool is not the same as in the diet. Strontium-90 losses for infants whose stable strontium excretion in urine
was not measured were estimated from those of Infants 26 to 37
(
see footnote “i”in Table XXXIII).
IMPERFECT COLLECTION OF URINE
The mothers reported that approximately one urination in twenty occurred during baths or diaper changes. Calcium,
Cantion O.182Ca’ + 66. XXXII. Strontium-90 losses were considered
to be proportional to stable strontium
losses, as discussed above.
LOSSES INHERENT IN BALANCE STUDIES
No losses during feeding and excreta col-lection by the mothers were observed
dur-ing 2 weeks near the beginning and end of
the study when nurses experienced in meta-bolic balance studies were assigned to
check procedures. Systematic losses are pre-dicted, however, even with careful practice
-a few drops of milk remaining in the hot-tie, or a small amount of feces adhering to the infants’ buttocks.6 A loss of 1% was esti-mated as the amount of food and excreta that might be lost without detection. In
terms of milk and feces-by far the main
carriers of calcium, stable strontium, and strontium-90-losses of 1% correspond to 6 ml and several hundred milligrams per day,
respectively. It was considered unlikely that average inherent losses would be even
twice as large. The magnitude of inherent
losses of 1% during feeding and excreta col-lection is shown in Tables XXXII and
XXXIII.
IMPERFECT SEPARATION OF URINE AND FECES
Although the protocol for collecting ex-creta was intended to provide urine sam-pies that contained no feces, small amounts of the latter may occasionally have
contam-mated the urine and been responsible for some relatively high values of calcium,
strontium, and strontium-90 in urine
(
Ap-pendix A
) .
No systematic correction was made for this effect because it did notoccur regularly. It is mentioned only to in-dicate that relations among urinary
sub-stances may have been affected. For exam-pie, the relations quantitated in Figure 18 and Equation 4-10 could be artifacts caused
by feces collected with urine.
The reverse-collection of urine with feces-was undoubtedly a routine occur-rence. From the relative number of diapers
containing “only urine” and “all feces,” it was estimated that 10% of daily urine was
collected with feces, and this correction is included in Table XXXIV. The correction increases urinary values, affects fecal values
only slightly, and does not change retention
values at all.
CORRECTION OF MEASURED VALUES
Corrections for average values of intake, urine, and feces are summarized in Table
XXXIV. Corrected average retention values
were obtained by subtracting the total
losses in Table XXXII from the gross
reten-tion
(
uncorrected intake-excretion) ,
oradd-ing strontium-90 “retention” in Table
XXXIII to this value. Alternately, they were
computed by subtracting sweat plus saliva losses and corrected excreta values from the
corrected intakes.
These corrections were also applied to
average values for subgroups such as In-fants 26 to 37 and infants separated
accord-ing to age. They would be meaningless if
used with individual values because the factors composing these corrections are
ex-pected to vary appreciably from sample to
sample.
CORRECTION OF EQUATIONS
Equations relating intake, excretion, and retention of the substances of interest were all based on measured values. To take sys-tematic errors into account, the corrections shown in Table XXXII and XXXIII were applied as follows, designating corrected values with primes. To convert Equation
2-6 to 2-8 for example,
(Equation 2-6)
Caos,ntion = 0. 19OCa11,
+
84(Equation C-6. 1)
Caetntion = Care,ntjon - (O.OlCain
(Equation C-6.2)
Ca0 = O.99Ca,
(Equation 2-8)
S’atiiple Intake
I rote
Systematic Error
Initerent
Loss (%) To (‘orrect Measured Value:
Multiply by 0.99
Total
Feces
5
10
16 Multiply by 1.19
(-10% of
urine)
Subtract (3-3)
Subtract (17-i) Subtract (9-4) Subtract (7-5)
=0 mg/day
= 15 mg/day =5 jig/day
=!2 jig/day
Subtract (0 .07-0 .05) =0 .02 pCi/day
Subtract (0 .10-0 .08) = 0 .0 pCi/day
(Equation C-6.7) Sra, Srj,,a, 2
TABLE XXXIV
SUMMAIIY OF CoilREc’rloNs
Total, Average calcium Average phosphorus
Average stable strontium (all values)
Average stable strontium (Infants 26 to
37)
Average strontium-90 (all values, and urine and feces separated)
Average strontium-90 (Infants 26 to 37) Inherent
Imperfect
Collection with feces
Inherent
Urine contribution
The parenthetical expression of Equation
C-6.1 does not include a correction for
Careces because this value is zero for
cal-cium; Ca88-calcium loss through sweat and saliva-is 13, and Caurin, is 26. Conversion factors for correcting other equations are listed below.
(1) Equation 2-7 to 2-9,
(Equation C-6.3)
1)
I retention - I retention
(Equation C-6-4)
- (O.O1P, - 15 + 28 + 21)
Pn = O.99Pin.
(2) Equation 2-10 to 2-11,
(Equation C-6.5)
Caetention = Caretentjon - 22
(Equation C-6.6)
I retention = Pretention - 36.
(3) Equation 3-2 to 3-6,
(Equation C-6.8) Srn 0.99 Sri,,.
(4) Equation 3-5 to 3-8 by Equation C-6.5 and
(Equation C-6.9)
Sretentjon = Srretentjon - 22.
(5) Equation 3-4 to 3-7 b’ Equation C-6.2 and
(Equation C-6. 10) Catrj,,e _ 1.19 Caur no
(Equation C-6.l1) Srri,,e l.19 Sruri,,.
The exact solution is
(Equation C-6.12)
p0.486 ,0.516
Srrjne 0.725 Cain Caurine.
INHALATION OF STONTIUM-90
The average inhalation rate by infants was estimated to be 3 m3 per day7 from sev-eral measurements of minute volumes in Se-dated infants and from a comparison in adults of overall inhalation rates with inha-lation rates at rest. Average daily inhalation of strontium-90 on airborne particles by
TABLE XXXV
ESTIMATED STH0NTIUM-9t) I N}IALATION BY INFANTS
“Sr -Peru;il Infa,iI Inhalation (I) (pci/da)
8-60 1,,4,6 0.0()9’
9--6() 3,4,6 0.009’
I0-60 , ‘2,3,4,6 0.009’
l1-60 1,4,6 0.009
W-6() 6 , 0.009
13-60 3 ,4 0.009
1-411 I,,3,4 0.006
-6l I,2,3,4 0.006
3-61 1,2,3,4,8 0.009
4-61 4,8,9 0.O12
5-61 8,9,12,13 0.021
6-61 8,9,12,13 0.024
7-61 9,W,13 0.015
8-61 I),1’2,13 0.006
9-61 l,I3 0.01
10-61 9,1 0.027
11-61 12,13,14,15,16,17 (1.021 I-.61 12,13,14,15,16,17 0.021 13-61 14,15,16,17,18,19 0.0.54
1-62 14,15,16,17,18,19 0.078 -62 14,15,16,17,18,19 0.060
3-6-. 14,15,16,17,18,19 0.07.5 4-6l 14,16,17,18,19 0.111
5-6-2 14,15,16,17,18,19 0.’201
6-6 18,19 0.147
7-6-2 18,19,21 0.114
b-(i2 18,19,21 0.084
9-62 21 0.063
1(1-6-2 21,24,25 0.075
l1-62 21,t2,23,24,2.5 0.063
l-62 22,23,24,2.5 0.051
l3-6 ‘2,23,25 0.0.54
1-63 2,23,24,23 0.066
-(i3 22,23,24,25 (1.038
3-63 22,23,24,25,26 0.111
4-63 23,24,’L5,’26 (1.186
.5-63 24,26,28,29 0.261
6-63 6,28,3() 0.288
7-63 26,28,29,3l) I 0.366
8-63 6,28,29 0.315
9-63 28,29,30,31 10-63 ‘26,28,21),30,31 11-63 28,9,30,31,32 H-63 28,’29,30,31,32,33 13-63 30,31,32,33,34 1-64 30,31,3’2,33,34 2-64 31,32,33,34,36 3-64 32,33,34,36,37 4-64 34,36,37 .5-64 34,36,37 0.192 0.186 (1.114 0.069 0.048 0.081 0.084 0.069 0.174 0.198
Figure 22. inhalation by a particular infant may differ from the average value because
of local meteorological conditions, the way his home was ventilated, and the infant’s
size and activity. The much higher intake
estimated ear1ier was predicated on the
absence of resorption and would not apply
at the resorption rates shown in Figure 21.
Ingestion of deposited airborne particles from surfaces
(
toys, and so forth) ,
how-ever, may have increased the intake of strontium-90.According to a simple model,’ 50% of soluble material such as strontium-90 is swallowed after inhalation, 25% enters the
blood directly from the lu.ngs, and 25% is exhaled. With this distribution, values
cor-rected for inhalation
(
shown with primes) can be written in terms of measured intake in food, ‘#{176}Srjn,and inhalation, I, as follows:(Equation C-7. 1)
#{176}Srng,tjon = 9#{176}Sr111+ 0.501
(Equation C-7.2)
9OSr’,j = Srat)sor;,tion + 0.751
(Equation C-7.3)
9OSr’ = 9#{176}Srretentjon + 0.751.
The corrected absorption value includes
1)0th absorption in the gastrointestinal tract and in the lung.
Corrections for inhalation are listed in Table XXXIII. For ingestion, the correction
is + 0.501. The average value of I, from the
values in Table XXXV, was 0.09 pCi per day for all periods, 0. 12 pCi per day for pe-nods in which urine and feces were sepa-rated, and 0.16 pCi per day for periods in which stable strontium balances were
ob-tamed. Higher concentrations of
strontium-90
in airborne particles(
see Figure 22) to-ward the end of the study led to the highervalues of
I
in the subgroups.As shown in Table XXXIII, retention is underestimated if the inhalation of strontium-90 is ignored. Compared to
aver-age retention values of 1.1 pCi per day, the
correction for inhalation is small but
signifi-cant. The greatest effect on individual
values occurred for very small retention values
(
including negative retention) and during the two peaks in concentrations ofstrontium-90 in 1962 and 1963. Results for
Infants 1 to 13 were almost unaffected by inhalation of strontium-90, but inhalation
increased the apparent retention of
strontium-90 by more than 10% in one third
of all periods.
REFERENCES
1. Swanson, W. W., and Job, L. V.; Loss of
mm-erals through the skin of infants. Amer. J. Dis. Child., 45: 1036, 1933.
2. Robinson, S., and Robinson, A. H.: Chemical
composition of sweat. Physiol. Rev., 34:202, 1954.
3. Table 50. Saliva, physical and chemical charac-teristics: Vertebrates (saliva content). In
Spector, W. S., ed. : Handbook of Biological
Data. Philadelphia: W. B. Saunders
Corn-pany, 1956.
4. Eisenberg, E., and Gordan, C. S. : Skeletal
dy-namics in man measured by nonradioactive strontium. J. Clin. Invest., 40: 1809, 1961.
5. Dolphin, C. W., and Eve, I. S. : The metabolism
of strontium in adult humans. Phys. Med.
Biol., 8:193, 1963.
6. Fomon, S. J., and Owen, C. M. : Comment on metabolic balance studies as a method of esti-mating body composition of infants.
PEDIAT-TRICS, 29:495, 1962.
7. Kahn, B., Seltzer, R. A., Hailbach, P., and
Straub, C. P.: Intake of radiostrontium in air-borne particles by infants. Health Phys.,
10:1043, 1964.
8. International Commission on Radiological Pro-tection: Report of ICRP Committee II on
permissible dose for internal radiation
(1959), with bibliography for biological
