LEAD ABSORPTION - Continued

mile of the smelter, 170 of 172 children (98.8%) had lead
levels 40μg/100ml; 1 (1.1%) of 89 children in a rural con-
trol area 45 miles distant had a lead level >40μg/100ml.

To determine routes of lead intake, lead levels were
measured in samples of soil, dust, pottery, and interior paint
collected at each home surveyed and in air samples collected
at 9 points in the study areas. Results indicated that lead
levels in soil, dust, and air were all high close to the smelter
and decreased with distance. Levels in paint were nearly
identical in all areas. Pottery was used for food handling in
only 5 (0.9%) of the 588 homes visited, and there was no
dangerous lead release (3). Significant correlations were
found between blood lead levels and exposure to lead in air
(coefficient of correlation, [r = 0.72]), surface soil (r = 0.59),
and interior dust (r = 0.23).

Seven (17.1%) of the 41 children with blood lead levels

>80ug/100ml had hematocrits <33%, while 8 (2.1%) of 390

children with blood lead levels of 40-79μg/100ml, and 8

(1.3%) of 616 with levels <40μg/100ml were anemic

(X2 = 37.04 for >80 vs. <80, p<0.00001). Free erythrocyte

protoporphyrin (FEP) levels increased logarithmically with

blood lead levels.

To evaluate subclinical neurologic functioning, motor

nerve conduction velocities (right peroneal nerve) were

measured in blind fashion in 183 5-9 year-old children from

the 6 areas near the smelter and in 39 from the con-

trol area (4). Data from 17 of these children (7 with

blood lead levels >40μg/100ml) were excluded from

analysis because of pre-existing neurologic disease, and re-

sults from 3 were excluded because data were incomplete or

unsatisfactory. The remaining 202 children were all appar-

ently healthy, none had frankly pathologic conduction ve-

locities, and all but 4 fell within 2 standard deviations of age-

rated means. However, a statistically significant negative

correlation was found in these 202 children between con-

duction velocity and blood lead level (r = -0.38, t = -2.12,

p<0.02 by 1-tailed t test). There was a similar correlation be-

tween conduction velocity and FEP (r = -0.40).† No signif-

icant relationships were noted in this group between conduc-

tion velocity and age, sex, or socioeconomic status.

Repeat blood testing in August 1975 by the State of

Idaho, Department of Health and Welfare indicated that a

significant reduction in lead levels had occurred since the

preceding year; the mean blood lead level in 74 children

living within 1 mile of the smelter who were tested in both

years decreased from 63.5μg/100ml to 47.3μg/100ml (p<

0.001). No children were found in the repeat testing to have

blood levels 80μg/100ml; however, 108 (71%) of 153 chil-

dren 1-10 years old living within 1 mile of the smelter and

210 (45%) of 471 children living from 1.0-2.5 miles, in-

cluding several new residents in both areas, had lead levels

>40ug/100ml. FEP levels in 1975 among 69 children living

within 1 mile of the smelter who were tested in both years

averaged 293.1μg/100ml rbc. Extensive monitoring programs

under the direction of the State of Idaho are underway and

are designed to follow each child until his blood level falls

below 40ug/100ml.

(Reported by JT Ashley, MD, JA Bax, PhD, JA Mather, MD,

State Epidemiologist, IH Von Lindern, MS, and AJ Yankel,

MS, Idaho Dept of Health and Welfare; RG Feldman, MD,

Dept of Neurology, Boston University School of Medicine,

Boston; Toxicology Branch, Clinical Chemistry Div, Bur of

Laboratories, and Environmental Hazards Activity, Cancer

and Birth Defects Div, Bur of Epidemiology, CDC.)

References

1. Medical aspects of childhood lead poisoning. Pediatrics 48:464.

468, 1971

2. MMWR 23(37):323, 1974

3. Klein M, Namer R, Harpur E, et al: Earthenware containers as a

source of fatal lead poisoning: Case study and public health consider-

ations. New Engl J Med 283:669-672, 1970

4. Feldman RG, Haddow J, Kopito L, et al: Altered peripheral nerve

conduction velocity, chronic lead intoxication in children. Am J Dis

Child 125:39-41, 1973

+ Eight months after initial nerve conduction velocity measurements,
all 6 children who tested below 45 m/sec were retested at the Depart-
ment of Child Neurology, University of Washington School of Medicine.
While the 6 children were found there to be within or above the
normal range for their age, the procedures used in this repeat testing
were not the same as those used in the original examinations.