Document 44Va5LYLqe7JLeDZDGN2aKkMG
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OF EVALUATION OF LONG-TERM EFFECTS/ELEVATED BLOOD LEAD CONCENTRATIONS '
IN ASIMPfCMATIC CHILDREN ' JAMES L. Me NEIL, M.D; Associate Clinical Professor of Pediatrics Texas Tech University School of Medicine El Paso, Texas
j.A. PTASNIK, Ph.D, Director Guidance and Special Education
El Paso Independent School District El Paso, Texas Th purpose of this paper is to contribute objective data toward the often .expressed hypothesis that subcllnical elevation of body lead burden may have permanent deleterious effects on the physical and men tal development of children, A unique group of children discovered accidentally presented a naturally occurring experimental model for the study. This group of experimental children with good nutrition., no anemia, and happy hemes in a three generation small community, leave elevated blood lead as an apparent isolated significant variable. The children were matched with a control group, tested on a blind, basis and the results analyzed for any significant differences. Results of the study are presented as objective evidence to aid In determining safe levels of lead exposure. Initial evaluation of this group of children suggest that prolonged exposure to subclinical lead levels in the 40-80 mcg$ range has not resulted in apparent deleterious effects*
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This study supported by grant LH-208 from International Lead and Zinc Research Organization,
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1, Introduction.
In January 1972, a -unique situation was discovered in El Paso,
Texas, which represented an opportunity to test the hypothesis that subclinical elevations of body lead burden in the 60-80 mcgjb range may
hav# a permanent deleterious effect in Children jd-J [2] f*3j[ Qb| . Sfeaeltertown, adjacent to a large smelter in operation for eight years
was found to be highly contaminated with lead. Blood lead screening test indicated 67# of the Z06 children residing there had lead values over 6-0 meg$,, El Paso incidence excluding Srneltertown (Old Fort Bliss, not
included in the study) was estimated at 2$ (Table l). 2, Clinical Model for Study.
' 2,1 Test Group, One hundred thirty eight of the 206 children agreed to participate
in this study. Sox distribution was 68 male and ?0 female. .Age distri bution was evenly distributed from 21 months to 18 years with a median
of 9 years (Table 2),
.
Availability of high lead content paint was low and-similar between
Sneltertown and El Paso, The sources of lead were presumed to be ambient air and contaminated soil from the smelter jjfj. Environmental conditions, consistent plant operations, serial blood lead determinations for two years and age distribution suggest that the Srneltertown children have had . sustained asymptomatic elevations in body lead burden,
2.2 Controls. Control groups were chosen from children residing outside of Smeltertown and were matched with those in Srneltertown by age, sex, race, and
family income, A second control group of pre-school age children was obtained from a rural community approximately 12 miles from the smelter,
2.3 Hatching. Spanish is the principal^language for all groups. More specific
control matching data for the lead test group, city group, and rural con trol group is tabulated in Table 3, The difference in income was probably related to the higher union wage paid by the smelter. Despite similar education and job rating, 19 of these 22 fathers were in the upper 2
income groups, 3, Procedure.
, All children were evaluated on a blind basis by examiners who were given only a study number, first name, and age for each child. Evaluation
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included a subjective history questionnaire obtained from the parents, a physical and neurological examination,, nerve conduction test, blood lead, hemoglobin:, hematocrit, EMA-14, erythrocyte protoporphryin,' and urinaly sis,,, . X-rays of the hands and wrist were made for .gross evaluation and computer analysis for bone weight, density, and size. The psychometric evaluation, using tests depending on age, included; WISP, WAIS, McCarthy Sca'l! es, Peabody, DratrA-Person, WRAT, Oseretsky, Wepuan Auditory Discri- r' rainatiom, Berry Visual Motor Integration, Prostig, and California Test of Personality.
4, Analysis. The experimental children and matched controls were grouped for analysis by blood lead levels. Other parameters of lead .exposure, ery throcyte protoporphryin levels, living in. area during Critical period'of birth to three years of age, total time in area more than two years, and positive X-ray findings were used in combination to seek out the high risk children. Those children with 4 of these 5 parameters positive were placed in a serious group, and those with 3 of 5 positive parameters were added' to the serious group to form a moderate group for analysis. Results were tabulated and preliminary statistical analysis were run using F Test of Equality of two Variances (f=S2l/ S2) and T Test, A probability level of 0,05 (5%) was used to compare groups for significant differences. Data is being analyzed for significant variables before more sophisticated statistical analysis is conducted, 5. Results. There are significant expected differences in time in area, blood lead values, and protoporphryin levels, to clearly separate the lead chil dren from the controls (Table 4). Pica was significantly higher in the lead group. This included ingestion of dirt and may represent increased awareness in reporting from the lead group parents. Fourteen non-specific complaints 'frequently mentioned as- symptoms of plumbism were infrequent and similar between test and control groups and were essentially noncontributory, Health history was good and similar between groups. General physical and neurological exam was normal. Finger to .thumb opposition and alternating hand movements showed expected variances with age but no difference with controls[6i Nerve conduction tests were normal.
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4.
Hemoglobin and hematocrit values ware normal. Group mean average
hemoglobin ranged from 14,3 grams in lead children loss than eight years
of age to 16,8 grams in total controls--adjusted for age to percentage of normal, the range was 98*1$ to 102.2$. Bight of nine lead groups were a
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shade lower but none were significant!;/ different.
1
SMA-14 values show seme minor differences statistically, but all
values are within normal, range.
Hyperactivity was not demQnstratedjjfJ. Test values are actually a /'[
shad in favor of lead children but differences were not statistically
!
.significant (fable 5)*
Psychometric Values are similar to those found in routine testing in |-
,El Paso Schools. The Peabody test slightly favors the Controls and Draw- ;
A-Person test favors the lead group, neither difference is significant. The WXSC gave a verbal IQ of 86.86 for lead against 86,94 for the
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control group, parformance IQ of 95*19 for lead against 93*06* and a
total IQ of 90*95 for lead against 88.69 for control group. These and
all subgroups show no significant differences.
The McCarthy Scales for 29 children under 6 years of age gave a
general cognitive scaled score of 85,24 for lead against 84.43 for the
control group and was not significant.
No significant differences occurred in the total group comparisons
of the WMT, Wepman, Bender, and Oseretsky tests (Table 6).
The most significant difference is in.the California Test of Person- j
ality, This shows in the total group but almost disappears in the mpder- 1
ate group. Group less than forty shows more significant differences than
group greater than sixty. This difference is more logically explained by geographic isolation, closing of Smeltertown School, news media exposure
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because of lead problem, and forced displacement from homesteads. 6. Conclusions. Ary source of lead causing undue absorption in humans must be con
trolled. From a practical standpoint, the practicing physician, con cerned government agencies, and industry must know what is safe,
Data from this study is still being analyzed for other possible subtle changes or trends, but Initial results support the current United States Surgeon General Guidelines for Safety[^8J.
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REFERENCES
'
1 WIENER, G,, "Varying psychological sequelae of lead ingestion In chiidren,,. Public Health Rep. , 85. 19-24, 1970,
2. RENNERT, O.H,, WEINER P., MADEEN, J,, Lead and CNS, Clinical Pediatric s, 913, January 1970*
3. CHISOLM, J,J, Lead Poisoning Scientific American, 224; 15-23, February 1971,
4 IXN-FU, J.S., "Undue absorption of lead among .children--a new look at mi old problem1', New England Journal of Hed ,286 s 13i 702-709, March 1972,
5 BARLTROP, D., Children and Bnyironnental Lead, Preprint Load in Enviromental Conf, Zoological Society of London, January 1972,
6 GRANT, W.W,, BOELSCHE, A.N,, ZIN, D., "Developmental patterns of two motor functions", Develop, Mod, Child Neurol, .15* 171-177,1973,
7 CLARK, D.O., BOEUER, K,, Lead and Hyperactivity, Saucot 2* 9OO-903, 1972.
8 Medical Aspects of Childhood Lo_sd. Poisoning., approved by STEINFELD, J.L., Surgeon Gon, USPHS Pediatrics, Vol* 481 ' 3, September 1971,
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Table I, LEAD SCOTUNS RESULTS '
-Limber of Children
SMELTERTDWI Study Group
Non-Study Group (13--no lead value)
EL PASO Initial City Tests
CDC and BCEM Pilot Screen
Mesita School Children
ILZBO Study Controls
Total
Blood Lead <40 tncg% > 40 mcg%
138 37 101 68 27 28
/ %>-40 mc^
73% 51%
75 550
69 142 '
75 538
69 140
.0
i12 2%
0
2
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AGE DISTRIBUTION IN' LEAD
AGE IN YEARS
O -* N>
W
NUMBER OF CHILDREN
Ui CT\ S 9 ' gj HJ
to S'
f-1 *
rc * * " *
if
*` '*
4- 4-
'* *
4-
u if 4- 4- 4-
i
.'
... 4* *4? ** * * * * * .
I'
Ui 4-if
5t-
{- If 4- 4- if * * 4-
& 4- 4- 4- 4- * 5f f if 4* 4* 4- *
1 ^ 4~ 4- 4- 4* 4- 4- 4 4\
.
> Q
o CMO
t-3 05 it- 4- it- if- 4- 4- if 4- if it- 4\ if
1
.-
c if if if if f if if if if if if '
t-- o
if
if
if
if . if
5f
if >f
.
3
s
>10-33
'
rm mm
Q
if if 4- 4- if if if if if if 4- if 4- if g
fs3 ,4- 4-
' 4 ' 4- ' 4- . . 4-
MUi 4- if f if 4- 4-
** if
4> 4- 4- 4- 4- 4- 4- 4- .4- 4-
V Ui if 4- if 4- 4- 4-
...
. .9 1n
4-4-4-
4- 4-
M OS I .4-
.
'
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table III, '
Average Age Difference Lead Under 8 Years
... FACE % Mexica^Americaxi Father
Mother
'.
Child
~jQB LEVEL Father
Mother
EDUCATION....................... Father
Mother
INCOME (Annual) Group Average
Dollar Approx, of Annual Income
comsoL m.TcaiN3 mm
Lead
City Control
- ,69 day
+- .69 day
+4.64 day
. 94% 97% . 96%
96% ' 99%
97%
1.53 1.06
1.43 1.10
7.54 years 7,27 years
7.83 years 6.77 years
2.27 4,540
1.92 3,840
Rural
-4.64 ./
95% 93% 96%
1,70 1.07 8.45 years 7.65 years 2.42 4,840
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Tiros In Area Father
' Mother Child
Blood Lead Total Moderate 8 years
Protoporprryin Total Moderate 8 years
Table TV, EFFECTED SIGNIFICANT DEFERENCES
Lead
.J.. rears
112 22
135 23
138 7
Control # Years
7 7 1/2
88
00
Rural # Years
2 9 1/2
00
0 o
y'"
M-50 M-61 M-56
(14r93) (14-93) (15-93)
M-20 (7-43) M-22 (8-40) M-23 (10-43)
M-16 (10-28) M-16 (10-28)
. M-186 (20-710) M-239 (68-710) M-135 (39-550)
M-80 (26-303) M-84 (26-303) M-91 (26-303)
M-67 (21-167) M-67 (21-167)
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Table V.
HYPEPAC3:T7ITY ev al u at io n
Groups
Total Fb. Con,
Estimate with Physical
6.10
6,51
Test with Physical
5,43
5.60
Parent Questionnaire 15.4
Teacher Questionnaire. 5,03
16.7 5.17
1'fad.Pb, 6,05 5,45
15.9 5.59
Rural Con. . Fb<8yrs. Con,
6.37 6,10
1.75
5.61 5.75
6.04
17.2 17.2
23.2
6,40 6.51
6.52
City Con. 7.25; 6.45
19.7 7.31
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TOTAL LEAD GROUT
WRAT
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wise
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w
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b o>
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h-> O ; O P Ml VO SO O j CP
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to p
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to a.
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MODERATE LEAD GROUP
Table VI. COMPARISON OF I.Q .
LEAEK 8 YR.& RURAL
AO 00 06 M l C o V O o CO CO
vo ; 00 co to p p
M i U* 3
c o .p
*to `fto
P, 'i o Op CTv to o
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pp
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to
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VO so do to -M so Ml Ml p
NCO3
hO CD
NO CO
N3 N3 n > to NO ' to CO to to to to
M H* CO 00 p
i--* > -* tO
N-1 :*
.
M N3
t--4 Q
t-> p-
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M
I-1 *
B4
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P*
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ho :K>
so
- r- ' . - -- --
-- -- .-- - ,--- .. --
4> VO Ml Mi - ------------ - i-
O oo
o p P p t--1 p
t-* o o
v0 05
S
o Cn
03 CO "to p b CO .hD M >- p o
b CO so *-* to co .
$
VO VO {- o CT\ P
CD vO M3 O o\ o
M J--1 sj
B-* M1
Vi ' Mi
o>
oo Vo VO
oo A O S3
CO
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B4 b NO
a -0VO
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vo o
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[-4
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SuO>
op H4 M N3 S3
CD o NO
oo
so
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S-J t-1 to
o to vo
to to to v O p v o P CTv p
P to p t--* V O o to u>
hO to NO to to to
P* t-1
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fo_4
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NO p to 0
00 p
M* Mi p
vo t o M
vp Ms to
so
to
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to cn
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M Ml cn P Ml cr>
DUP040009043
RURAL & CITY CONTROL