A Nationwide Survey of Heavy Metal Absorption in Children

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AMEHJCAN JOURNAL OF EFIDEMIOLOOY Vol 106, No. 4

Copyright O 1977 by The Johns Hopkins University School of Hygiene and Public Health Printed m USA.

Original Contributions

A NATIONWIDE SURVEY OF HEAVY METAL ABSORPTION IN CHILDREN

LIVING NEAR PRIM ARY COPPER, LEAD, AND ZINC SM ELTERS

EDWARD L BAKER, JB . ,1 CARL G HAYES,1 PHILIP J. LANDRIGAN,1

JAN L. HANDKE,1

RONALD T. LEGER,3W. JERE HOUSWORTH' AND J. MALCOLM HARRINGTON 1

Baker, E.L., Jr. (CDC, Atlanta, GA 30333), C.G. Hayes, P.J. Landrigan, J.L.

Handke, R.T. Leger, W.J. Hous,worth and J.M. Harrington. A nationwide sur-

ve y of heavy metal absorption in children living near primary copper, lead,and zinc smelters. AmJ Epidemiol 106: 261-273, 1977.

Arsenic, lead, and cadmium absorption levels were determined in 1774

children 1-5 years old living in 19 USA towns with primary nonferrous metal

sm elters. Results were com pared w ith data on 258 children of the same age inthree communities without smelters. Increased systemic absorption of ar-

senic, as reflected by urine arsenic content, was noted in children near 10 of

11 copper smelters. Blood lead levels were also modestly elevated near two

copper smelters. Near lead and zinc smelters, elevated levels of lead and

cadmium In hair provided evidence of external exposure to these elements.Levels of lead In blood were not, however, elevated near any of three leadsmelters and were elevated near only two of five zinc smelters. Blood cad-

mium levels were high near one lead and two zinc smelters. The apparentsources of exposure (except in one community with elevate d levels of arsenicIn drinking water) were air, soil, and dust contaminated by smelting opera-

tions. While the full biologic significance of these findings is not known,exposure of children to toxic heavy metals emitted by smelters should be

reduced to a minimum.

air pollution; arsenic; cadm ium ; environme ntal h ealth; lead ; water pollution

Increased absorption of lead and arsenic me tal smelters in the United States (1-4)by children living near certain nonferrous and abroad (5-10) has been documented.

Inhalat ion and ingestion of metallic par-Received for publication February 4,1977, and m t iculates emitted by the smelters appear to

final form June 20, 1977. ha ve accounted for the increased absorp-Abbreviations: AA atomic absorption spectro- t i o n Disruption in heme biosynthesis (2,

photometry; EP, erythrocyte protoporphynn; ppb, , , . , - . , , , , , ,, ,1 O .

^pertalhonipSTpartrpermiUim.n>

and f a t a l l e a dencephalopathy (12)

1Environmental Hazards Activity, Cancer and have been the reported consequences; sub-

Birth Defects Division, Bureau of Epidemiology, clinical damage to the central and periph-

Center for Disease Control, Atlanta, GA 30333. (Re- , i. u u \- J •

print requests to Dr. Landngan.) era l nervous systems has been noted in

• Population Studies Division, Health Effects Re- two Studies (2, 11) and not observed in One

search Laboratory, Environmental Research Cen- investigation (13) of children exposed to

ter, US Environmental Protection Agency, Re- i j u . • • T • f , i

search Triangle Park, NC.l e a d

smelter emissions. In view of these3

Phoenix Laboratories Division, Bureau of Epi-demiology, Center for Disease Control, Phoenix, Folland, M.D.; Stephen Hindman, M.D.; Sharon S.AZ. Hodges; Harry F. Hull, M.D.; John E. Jacobson,

Nationwide Smelter Study Group: Carol E. An- M D.; Wm. Dan Keith, M.D.; Betty Menard; Ramonderson, M.D ; Pat Angel; Alan G. Barbour, M.D.; Moncado, M.D.; Wendy A. Peterson, M D.; PatrickMary E.H Boyd; Judith Charlton; Dennis Cox, E. Phillips, D.V.M.; Homer Pinson, Caroline Rak-Ph.D.; Andrew G. Dean, M.D.; Alexander E. Denes, iewitz; D. Michael Shasby, M.D.; Joseph Smith,M.D.; Betty Easton; Larry D. Edmonds; David S. M.D.; Hannah Webster, Mark E. White, M.D.

261

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262 BAKER ET AL

findings, the Center for Disease Control(CDC) and the Environmental ProtectionAgency (EPA) unde rtook in 1975 to surveyth e ex ten t and severity of heavy me tal

absorption in children living near primarynonferrous smelters throughout theUn ited S tates . This report summ arizes theresults of the survey.

MATERIALS AND METHODS

Study design. The 19 smelters selectedfor study represent all the primary lead,zinc, and copper smelters in the UnitedStates where community exposure to me-

tallic emissions had not previously beenstudied. Previously studied primary non-ferrous smelters are located in El Paso,Texas; Kellogg, Idaho; Tacoma, Washing-ton; and East Helena, Montana. Onlythose smelters were surveyed (table 1)wh ich w ere in operation M ay 1 , 1975, orwhich if closed on that date, resumed pro-duction within the following six months,and which were located within 8 km (five

miles) of a residential are a. T here w ere nohomes w ithin 8 km of th e copper sm elter in

Garfield, Utah. Studies in the vicinity ofeach smelter were restricted to childrenone to five ye ars (12-71 m onths) of age, theage-group previously shown (1 , 2, 14) to be

at highest risk of heavy metal absorptionfrom environmental exposure. Althougharsenic is, strictly speaking, not a metalbut a metalloid, we will, for the sake ofsimplicity, refer to all the elements dis-cussed in this report as heavy metals. Thesurvey area around each smelter (with ex-ceptions as noted below) was a circle 6 kmin diameter with the main smelter stack atthe center. We estimated that to obtainstatistically adequate data on the preva-lence of heavy metal absorption would re-quire in each area a sample of 60-100 chil-dren. We chose the first house in each areaat random and the re st of the sample usin ga sampling frequency that varied from ev-ery house to every tenth house dependingupon population density. All children oneto five years old in a selected house wereeligible to participate. There were no sub-stitutions allowed for families that refusedto participate or could no t be reached. Two

TABLE 1

Hair arsenic levels (ftglgm) m children m US smelter and comparison towns, 1975

City

Comparison townsAlbuquerque, NMPerryville, MOSafford, AZ

TotalCopper smelter towns

Ajo, AZAnaconda, MTCopper Hill, TNDouglas, AZHayden, AZHurley, NMMcGill, NVMiami, AZMorenci, AZSan Manuel hZ

White Pine, )JO.

Total

No of samples

22 ( 3)t86 (16)t52 ( 2)X

160 (21)t

858692 ( T)%

95 ( l) t104 ( l) t93 ( 7)t47 ( 2)t789814 ( 4)t

80 ( 2)X

872 (24)t

Mean

09

.08

.1 0

.09

1.9219 88

.1 4

.43

2.011 7

.36

47

.31

. 1 8

.42

2.60

(81)

( .01)

( .01)

( .01)

( .01)

( .14)

(1 .93)

( .01)

( .02)

( .14)

( .01)

( .04)

( .05)

( .02)

( .04)

( -09)

( .27)

Median

.09

.06

.09

.08

1.5415.60

. 1 1

.40

1.780.160 2 6

0.380.260.16

0.270 3 8

No. ele-vated*

042

6

85862590

103353570716

51657

t valuet

13.1010.264 41

14.82

14.206 916.187.32

11.642.43

3.549.22

* Number exceeding 95th percentile value (0.17 /ig/gm) of three comparison towns.t Student's t test comparing smelter town mean with mean of all comparison towns.t Number of samples with value below detection limit of test.

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A N A T I O N W I D E S U R V E Y O F H E A V Y M E T A L A B S O R P T I O N 263

cities contained two smelter stacks; chil-dren living within 3 km of either smelterconstituted the population sampled. Onesmelter was located near the US-Mexicanborder, a separate sample was drawn from

children in Mexico living within 3 km ofthe smelter, and results of testing in Mex-ico will be reported separately. In twosparsely populated locations (Bixby andGlover, Missouri) children living within 8km of the sm elter ma de up the study popu-lation.

Three comparison towns withoutsmelters were selected in New Mexico,

Missouri, and Arizona, areas of the nationwith the m ost sme lters. Two of these com-parison communities were rural and onewas urba n so as to approxim ate the r ura l-urban distribution of smelter communi-t ies. Children were selected from thesetowns in a manner similar to that de-scribed above for smelter towns.

Data collection

We conducted door-to-door interviews atselected households. After obtainingsigned parental permission, we took fromchildren samples of venous blood, urine,and full-length hai r, sto ring them in trace-metal-free containers. Data collected in-cluded the age and sex of tested children,length of residence at cur ren t and previousaddresses, history of pica, and history ofexposure to pottery used for culinary pur-

poses.Laboratory analyses. At each of the

three lead smelters, blood samples wereanalyzed for lead, cadmium, and erythro-cyte protoporphyrin (EP) concentration,and hair samples for lead and cadmium.All analyses except certain "split" sampleanaly ses were performed by Stewa rt Labo-ratories, Inc. (Knoxville, Tennessee). Ateach of 11 copper smelters, blood sampleswere analyzed for copper, lead, zinc, andEP concentration, urine samples for ar-senic concentration, and hair samples forlead and cadmium concentration. At eachof the comparison towns, blood samples

were analyzed for lead, zinc, cadmium,copper and EP concentrations, urine sam-ples for arsenic concentration, and hairsamples for lead, cadmium, and arsenicconcentration.

The minimum sample size required bythe contract lab oratory was 1 ml of blood,0.2 gm of ha ir, and 25 ml of uri ne. Detec-tion limits for these size samples were: 1ppb for arsenic, 10 ppb for copper, 10 ppbfor zinc , 10 ppb for lead using conventionalatomic absorption (AA) or 0.5 ppb usingflameless AA, and 1 ppb for cadm ium u s-ing conventional AA or 0.02 ppb using

flameless AA . Ce rtain samples of less tha nth e requ ired size we re processed by a sepa-rate laboratory using a separate methodol-ogy; these resu lts w ere not used for sta tis-tical comparison but were reported to par-ents .

The con tract laboratory conducted an in-ternal quality control program and partici-pated in a program of external controls.The internal program encompassed blind

split-sample analyses for hair, blood, andurine; blind random analyses of standardreference samples, recovery and precisionstudies from two large, composite samples(blood and hair), and the analysis of stan-dar d sam ple splits with two reference labo-ratories . Results of this program havebeen published p reviously (15). Studies bythe contract laboratory revealed 99 percent, 98 per cent, and 97 per cent recovery

of copper, zinc, and lead, respectively,from whole blood samples. The principalexternal control on blood lead analysisconsisted of CDC's submitting to the con-tract laboratory 39 bovine blood speci-mens, the lead content of which had beenthoroughly documented through CDC'sProficiency Testing Programs. The degreeof correlation between the CDC resultsand those of this contract laboratory washigh (r = 0.96); the contract laboratoryvalues were, on the average, 4 per centhigher than the CDC values .

Analytical methodology. Blood: Eryth-rocyte protoporphy rin (EP) \; as assayed by


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264 B A KE R E T A L

the technique of Granick et al. (16). Fol-lowing EP determination, blood sampleswere acid-digested and analyzed for copperand zinc by conventional atomic absorp-tion technique (17), and for lead by directflameless AA spectrophotometry (with useof a graphite furnace with multi l ineartem peratu re programming and s imultane-ous background correction) (1 8). C admiuman aly sis w as performed on a 250 /xl sampleof the original undigested blood specimenwith flameless AA in a pyrolytic graphitetube (18).

Urin e: Sample preparation of urine sam-ples consisted of ashing with a mixture ofnitric, perchloric, and sulfuric acids. Theash was treated with ammonium oxalateto remove HN0 3 . Samples were then ana-lyzed by hydride evolution AA technique(19).

Hair: Samples were agitated for 30 min-utes in a non-ionic detergent and thor-oughly rinsed with distilled deionized wa-ter. After drying, the samples were acid-digested as described above for blood sam-ples.

Lead and cadmium determinations weremade with conventional AA spectropho-tometry (17). Arsenic concentration wasdetermined by the hydride evolution-AAtechnique .

Statistical methods. Mean values of theconcentrations of metals in biologic sam-ples were calculated for each town; sampledeterminations below the detection limitwere estimated by substituting one-halfth e detection limit value for all "less than "values. Median and 95 percentile valueswere also determined. Arithmetic meanswere used for all calculations except thoseon urine arsenic, which were logarithmic-ally transformed to make a positivelyskewed distribution more normal (noclaim is made here for log normality).Data from the three comparison communi-ties we re pooled to form a sing le 258-mem-be r control group; th e proced ure is justifiedon the grounds tha t there w ere only m inordifferences among the three control towns

in the m ean concentration of heavy m etalsin hair, blood, and urine of residents. Al-though variances were often not homoge-nous, ^-statistics were used to comparemean values for each smelter town withthe pooled means from the control com-munit ies . The lvalues are shown in thetables along with th e sam ple sizes, m eans ,and variance. No particula r nom inal valuefor significance w as chosen, because distri-butions were often not Gaussian. How-ever, values of t greater than 2.58 suggeststatistically significant differences. Toev alua te the effect of du ratio n of residenc enear and residential distance from the

smelter on blood, hair, and urine levels,simple linear regressions were performedbetween these variables .

RESULTS

Sample completion. Interviews and atleast one blood, hair , or urin e sam ple wereobtained in 1234 (83.8 per cent) of the 1473households with children selected to par-ticipate in the survey . T here were 133 re-fusals (9.0 per cent), and 106 families (7.2per cent) could not be reached despite re-peated visits. Survey completion ratesranged from 74.3 per cent in zinc smeltertown s to 90.4 per c ent in lead sm elter loca-tions.

Copper smelters. Hair arsenic levelswere significantly high er th an comparisonvalues in every copper smelter town. Inone smelter location, the mean level was200 times the level in the comparisontowns (table 1). Mean urine arsenic levels(table 2) in children living near coppersmelters were higher in 10 of 11 townsthan the comparison mean. Arsenic levelsin hair tended to reflect urine arsenic con-centrations: highest mean levels in bothsamples were noted in Ajo, Arizona, Ana-conda, Montana, and Hayden, Arizona;lowest levels for both were in Copper Hill,Tennessee and Hurley, New Mexico.

Blood lead levels showed no consistenttren d in copper sm elter towns (table 3) andEP levels were not significantly elevated

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A NATIONWIDE SURVEY OF HEAVY METAL ABSORPTION 265

T A B L E 2

Urine arsenic levels (fig/liter) in children in US smelter and comparison towns, 1975

City



Ajo, AZAnaconda, MTCopper Hill, TNDoug las, AZHayden, AZHurley, NM

McGill, NVMiami, AZMorenci, AZSan Manuel, AZWhite Pine, MI

Total

No. of samples

51 ( 4)t81 (19)$61 ( 6)t

193 (29)t

774064 ( 4)t8083 ( 2)t57 ( 3)t

4872 ( 2)t77 ( l)t55

59 ( l)i

712 (13)*

Geometricmean

6 9

3.9

8. 2

5 8

80.830.8

8. 4

18.727.4

6. 9

14.115.315.822.312.2

18.7

95% confidence in-terval of mean

5.0- 9.52 8 - 5 45 8- 11 .5

4.7- 7.0

64 7-100 824 5- 38.8

6 0- 11.715 1 - 23 122.2- 33.9

5.2- 9.2

10 4- 19 112 .0- 19.512 8- 19.518 0- 27 68.9- 16.7

17 1- 20.5

Median

7.85.1

10.8

7.3

100 032.99.6

20 731.4

6.6

1 1 615.316 526 313.0

19 8

No ele-vated*

2

3

4

9

56

12

6

12

232

76679

146

t valuet

17.6611.02

1.908.11

10.711.07

4906.266939.234.06

10.75

* Number exceeding 95th percentile value (45 5 /ig/liter) of three comparison towns.t Student 's t test companng smelter town mean with mean of all comparison towns.t Number of samples with value below detection limit of test

(table 4). Mean hair lead (table 5) and hair

cadmium (table 6) values in children nearevery copper smelter were higher than incomparison towns but were considerablylower than in children near lead smelters.

Zinc smelters. Hair cadmium levels (ta-ble 6) were significantly elevated in chil-dren living near all five of the zincsmelters. Blood cadmium levels (table 7)near two smelters were significantlyhigher than comparison values. The high-

est blood and hair cadmium levels wereseen in Baftlesville, Oklahoma: averageblood levels there were 2.5 times the con-trol levels, and average hair levels werenine times higher. Blood lead levels weresignificantly elevated around two zincsmelters (Amarillo, Texas and Bartles-ville, Oklahoma); EP levels were elevatednear one (Palmerton, Pennsylvania) .

Lead smelters. Mean blood and cad-

mium levels in children living near thethree lead smelters studied were notgreater than levels in comparison towns;in fact, blood lead levels in Bixby andGlover, Missouri, and blood cadmium

levels in Bixby were significantly lower

than comparison levels (tables 1 an d 3). Incontrast, mean hair lead and cadmiumlevels at all three lead smelter locationswe re four to 13 t imes higher tha n compari-son values, indicating substantial externalexposure (tables 5 and 6).

Ajo, Arizona: Exposure to arsenic indrinking water. Mean urine arsenic levelswere higher in Ajo children than in anyother group tested. This town also had the

highest levels of arsenic in drinking waterof the Arizona towns surveyed (table 8).Many families in Ajo purchased bottledwater for various household uses, primar-ily drinking and cooking. To evaluate thecontribution of arsenic in drinking waterto total arsenic exposure, a separate sur-vey was conducted regarding water con-sumption patterns among families withchildren in the initial survey. Increases in

urinary arsenic levels were associatedwith heavy consumption of tap water (ta-ble 9).

Anaconda , Mo ntana: High arsenic ex-posure and absorption. The mean hair ar-


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2 6 6 BAKER ET AL

TABLE 3

Blood lead levels (iigllOO ml whole blood) in children in US smelter and comparison towns, 1975

City

Comparison towns

Albuquerqu e, NMPerryville , MOSafford, AZ

TotalLead smelter towns

Bixby, MOGlover, MOHerculaneum, MO


Ajo, AZ

Anaconda, MTCopper Hill, TNDouglas, AZHayden, AZHurley, NMMcGill, NVMiami, AZMorenci, AZSan Manuel, AZWhite Pine, MI

TotalZinc smelter towns

Amaril lo , TXBartlesville, OKCorpus Christi, TXMonaca, PAPalmerton, PA

Total

No. of samples

818692

258

482 3 ( l ) t

87

158(1)

1 05

64

86

97

1 00

42

50

94

10010170

909

84

87 (l) t12

62

1 02

347 (1)

Mean

17 7016.88

15 26

16.56

13.76

12 05

18.80

16.34

12 55

13 38

16.63

20.47

21.24

14 33

9 1 5

17 00

13.87

18 .01

18 62

16.36

22.34

28 60

19 02

14.84

17 .51

2 1 0 4

(SK)

( .63)( .74)

( .71)

( .41)

( 96)

(1.19)

( -94)

( .66)

( 46)

( 95)

( 74)

( .86)

( .85)

(1.23)

( 52)

( .74)

( .56)

( .55)

( -74)

( -25)

(1.16)

(1.91)

(1.42)

(0.82)

(0-60)

(0.66)

Median

17 .815 .0

14 .2

15 .8

1 3 8

13 . 1

16 4

15 .2

1 1 . 9

13 .3

15 .3

19 8

19 .9

13 .6

9. 0

16 .8

12 .6

17 .4

17 .9

1 5 4

20 .2

23 .3

1 8 6

12 .6

16 .7

18 .3

No . elevated*

54

3

12

0

0

1 0

1 0

1

3

5

1 5

1 2

2

0

5

2

4

4

53

10 (1)5

34 (1)5

0

2

3

49 (2)5

/ valuet

-2 . 6 8-3 . 2 0

2.29

-0 . 2 8

- 6 . 5 1-3 . 3 7

0.084.114.96

- 1 . 9 9- 1 1 . 2 9

0.54-3 64

1.982.37

-0 . 4 0

4.726.171 29

- 1 . 8 71 27

5.79

* Number exceeding 95th percentile value (29.4 /ig/100 ml) of three comparison towns.T Student 's t test comparing smelter town mean with mean of all comparison towns.t Number of samples with value below detection limit of test.5 Number greater than 80 jtg/100 ml in parentheses.

senic lev el for childre n in A nacon da w as km of the Anaconda sm elter. H air levels ofapproximately 200 times the m ean level in children attend ing school nea r the Tacomach ildre n in com parison towns , and urin e sm elter ranged from 20 to 100 /ag/gm com-arsen ic levels w ere also strikingly ele- pared with a rang e in this study of 1.5-120

va ted . U rin e arsenic levels we re slightly Mg/gm for pre-school children in Ana-lower th a n those reported in a study of conda.

children exposed to arsenic near a copper Bartlesville, Oklahoma: Increased cad-smelter in Tacoma, Washington (3). The mium and lead absorption. The highestarith m etic me an urin e arsenic level for me an blood cadmium, ha ir cadmium , andchildre n n ea r the Anaconda sm elter was blood lead levels encountered in the entire

39 /xg/liter whe reas th e me an levels for study were in the child ren tested in Bar-Tacom a children living at comp arable dis- tlesville, and th e m ean ha ir lead leveltan ces (1 .6-3 km) from the smelter were the re was higher tha n in any other zinc60-80 jig/liter, no children lived with in 1.6 sme lter town. Althoug h we saw no o vert


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A NATIONWIDE SURVE Y OF HEAVY METAL ABSORPTION 267

cases of lead poisoning in Ba rtlesville, theblood lead levels in some children exceededthe level (80 /xg/100 ml) where symptomsor signs of lead toxicity begin to appear.No relationship was noted between leadlevels and proximity to the smelter.

Factors associated with exposure andabsorption

Consistently negative correlations werefound between ithe distance of a child'sresidence from th e sm elter and the leyel ofcadmium, lead, and arsenic in hair (i.e.,higher levels were noted in children near

the smelter). Hair lead levels were nega-

tively correlated with distance near everylead smelter, four of five zinc smelters andeight of 11 copper sm elters (figure 1 ).These correlations were statistically sig-nificant (p < .01) in three locations(Glover, Herculaneum and Palmerton).Negative correlations between hair cad-mium and distance were noted in everylead and zinc smelter town and in eight of11 copper sm elter tow ns; significant corre-lations were found in two towns (Palmer-ton and Amarillo). Distance and hair ar-senic levels were negatively, but not sig-nificantly, correlated in seven coppersmelter towns. No consistent relationships

T A B L E 4

Blood erythrocyte protoporphynn levels (fig1100 ml whole blood) in children m US smelter and comparison

towns, 1975

City


Total

Lead smelter townsBixby, MOGlover, MOHerculaneum, MO


Ajo, AZ

Anaconda, MTCopper Hill, TNDouglas, AZHayden, AZ

Hurley, NMMcG ill, NVMiam i, AZMorenci, AZSan Manuel, AZWhite Pine, MI


Amarillo, TXBartlesville, OKCorpus Christj , TXMonaca, PA

Palmerton, PATotal

No. of sam-ples

82

86

92

26 0

48

23

99

170

105

64

86

97

100

4250

94

100

101

71

91 0

84901263

102351

Mean

26.06

2 1 . 0 1

2 3 . 1 8

23 37

33 .93

22 .20

26 .67

2 8 . 1 1

22 .09

26 .90

18 .52

30 .06

30 .51

26 .0819 .32

27 .57

23 .77

23 .81

17 .39

24 .47

26 .85

26 .50

26 .78

25 .90

30 .38

27 .61

(81)

(1.43)

(0.91)

(1.20)

(0 70)

(3.58)

(2.80)

(1.90)

(1.57)

(0.98)

(1.75)

( .63)

(1.99)

(1.88)

(1.82)( .61)

(1.65)

(1.33)

(1.10)

( -55)

( .46)

( 1 . 7 1 )

(1 .79)

(3.84)

( .92)

(1-93)

( -86)

Median

22.4

19.2

20.2

20.6

24.9

18 1

20.0

20.6

19.8

23.9

18.2

24.4

24.7

22.418.8

23.7

20.2

21.5

16.5

21.2

22.7

20 1

19.9

24.6

25.6

23.7

No. ele-vated*

525

12

102

16

28

181

1618

308440

63

6712

1127

t valuet

2.90

- 0 . 4 7

1.63

2 77

- 1 . 0 1

2.14

- 5 . 1 6

3.18

3.57

1.44- 4 . 3 7

2 35

0.27

0.34

- 6 . 7 2

1.32

1.89

1.63

1.02

2.19

3.41

3.83


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268 BAKER ET AL.

TABLE 5

Hair lead (figlgm) in children m US smelter and comparison towns, 1975

City

Comparison townsAlbuquerque, NMPerryvi l le , MOSafford, AZ

TotalLead smelter towns

Bixby, MOGlover, MOHerculaneum, MO


Ajo, AZ

Anaconda, MTCopper Hill, TNDouglas, AZHayden, AZHurley, NMMcGill, NVMiami, AZMorenci, AZSan Man uel , AZWhite Pine, MI


Amanl lo , TXBartlesville, OKCorpus Chnst i , TXMonaca, PAPalmerton, PA

Total

No of samples

228652 ( W

160 ( 1)

2030 ( l)t76

126 ( 1)

85 ( 2)t

869295 ( 3)t

1 04

93

47 ( 5)t789814 ( 4)t80 ( 4)t

872 (18)

3979376574

294

Mean

17.4312.5911.65

12.95

169.4949.5363.99

77.29

18.91

25.5722.8525.9426.2420.5314.3831 6818 4214.5013.11

22.03

38.8656.6645 0220.4344.46

4175

(81)

( 2 57)( 104)( .98)

( .74)

(29.17)( 8.06)( 6 09)

( 7.38)

( 148)

( 1.61)( 1.48)( 1.84)( 1.51)( 181)( 1.36)( 2 08)( 1.37)( 2 71)( 1.09)

( .53)

( 3.46)( 8.25)( 3 72)( 2.36)( 4 28)

( 2.70)

Median

13.29. 6

10 1

10.1

177 045 844.3

49 3

14 8

24.720.622.222.915.512 128.814.812.410 8

18.0

32.838.345 713.631.8

30.7

No. ele-vated*

34

0

7

1 8

17

54

89

1 5

271 8

24

26

1 2

2

28

7

0

3

1 62

1 946

22

1 1

34

1 32

t valuet

5.364.527 36

8.68

3 60

7.105.986.547.883.87

.9 2

8.483.51

.59

0.12

9 93

7.335.288.453.027.26

10.30

* Number exceeding 95th percentile value (33.4 figlgm) in comparison townst Student 's t test comparing smelter town mean with mean of all comparison towns.t Number of samples with value below detection limit of test.

were noted between distance and bloodand urine levels of the metals studied. Noconsistent relationships were noted be-tween blood, hair, or urine levels andlength of residence near the smelter orage .

A positive history of pica was obtainedfor 42.6 per cent of the children tested inthe smelter towns and for 43.0 per cent ofthose in the comparison communities. The

percentage with positive history variedconsiderably among areas, with a range of5-86 per cent. There were no positive cor-rela tion s found betwe en history of pica and

blood lead, blood cadmium, or urinary ar-senic concentrations.Pottery was used for culinary purposes

in 4.1 per cent of homes in sm elting tow nsand 3.1 per cent in comparison communi-ties. Except in Douglas, Arizona, where18 per cent of children were exposed topottery, and Miami, Arizona, where theexposure rate was 11 per cent, the percent-age of children exposed in any tow n did no t

exceed 7 per c ent. M ean h ai r lead, bloodlead, blood EP, and urine arsenic levelswere not significantly greater in childrenusing pottery than the levels in unexposed

a t Uni v e r s i t i P u t r a M a l a y s i a onA pr i l 1 8 ,2 0 1 2

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children in Douglas and Miami (p > .05,Student's Y' test).

DISCUSSION

This nationwide survey of heavy metalabsorption in children living near smelterswas prompted by the recent findings ofincreased lead and arsenic absorption inchildren living near smelters in El Paso,Texas (1), Kellogg, Idaho (2), and Tacoma,Washington (3). We found that increasedexternal exposure to toxic heavy metals,as evidenced by increased amounts ofthese metals in hair, was occurring in chil-

dren near virtually every smelter we stud-ied. Systemic absorption, as reflected byconcentrations of heavy metals in bloodand urine, was somewhat less common,

but was evident near 10 of 11 coppersmelters and near two of five zincsmelters . In no instance, however, did theextent or severity of increased absorptionapproach that noted in Kellogg or El Paso.By analogy with the findings in thosecities, it would appear that inhalation andingestion of metallic participates depos-ited by the smelters in air, dust, and soilwere the major routes of increased uptake.

T A B L E 6

Hair cadmium (/jg/gm) m children in US smelter and comparison towns, 1975

City

Comparison towns

Albuquerque, NMPerryville, MOSafford, AZ

Total

Lead smelter townsBixby, MOGlover, MO

Herculaneum, MO

Total

Copper smelter townsAjo, AZ

Anaconda, MTCopper Hill, TNDouglas, AZ

Hayden, AZHurley, NM

McGill, NVMiami, AZMorenci, AZSan Manuel, AZWhite Pine, MI

Total

Zinc smelter townsAmarillo, TX

Bartlesville, OKCorpus Chnsti, TX

Monaca, PAPalmerton, PA

Total

No . of samples

22 (10)*

86 (11)*

52 ( 7)*

1 60 (28)*

20 rj

30

76

1 26

85 ( 1)*

86 ( 4)*

92 ( 3)t95 ( 9)t

1 04

93 (12)*

47 (23)*78

98

1 4 ( 5)*

80 (14)*

87 2 (71)*

39 ( 6)t8037 ( 4)*

65

74 ( 1)*

295 (11)*

Mean

41

1.04

.9 6

93

7.93

6.35

4.26

5 34

2 6 8

1 8 7

2 72

1.72

1.78

1.47

.7 71.90

1 9 6

.9 0

1 5 6

1.88

3.58

9.14

2.54

2 . 1 3

7.29

5.57

( M )

( 08)

( .13)

( -14)

( .09)

(1.42)

( .94)

( .45)

( .43)

( .22)

( .16)

( .43)

( .15)

( .12)

( .14)

( ID( .16)

( .13)

( .21)

( -25)

( .07)

( .79)

( 1 5 4 )

( .39)

( .30)

( -92)

( .52)

Median

0.27

0.61

0 51

0.51

7 08

4 .82

2 .96

3 55

2 12

1 4 9

1.95

1.42

1.44

1.14

.571.69

1.69

0.89

1.03

1.44

2 .07

5.44

1.88

1.40

4 .42

2 .91

No. ele-vated*

0

5

2

7

1 6

1 9

38

73

27

1 7

281 3

1 6

1 0

11 3

201

1 0

1 56

1 4

57

8

1 4

54

1 47

( valuet

4 .94

5.76

7.28

10 .03

7.57

5.23

4 .08

4 .67

6.05

3.27

- 1 . 1 65.556.62

-.082.42

8.76

3.365.324.07

3.926.93

8.80

* Number exceeding 95th percentile value (2.91 /xg/gm) of comparison towns.t Student's t test companng smelter town mean with mean of all comparison towns.* Number of samples with value below detection limit of test


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270 BAKER ET AL.

Blood cadmium

T A B L E 7

ml whole blood) in children in US smelter and comparison towns, 1975

City No of samples Mean (re) MedianNo ele-vated* t valuet

Comparison towns

Albuquerque , NM 82Perryvi l le , MO 85Safford, AZ _92

Tota l 259Lead sme l te r towns

Bixby, MO 48Glover, MO 23H e rc u la n e u m, MO _48

Total 119Zinc smelter towns

Amari l lo , TK 84 (4)t

Bartlesvil le , OK 77 (l) tCorpus Chris t i , TX 12Monaca, PA 63 ( l ) tP a lme r to n , PA 102

Tota l 338 (6)t

2 122

1 8

20

1 2

1 6

33

2 1

1 2

50

1 7

22

36

30

(.01)(.02)(.01)

(.01)

(.01)(.02)(.04)

(.02)

(.01)

(.06)(.02)(.04)

(03)

(.02)

.20

.1 9

.1 7

.1 9

.0 9

.1 3

J 7. 1 5

.1 0

.33

.1 5

.1 5

.26

1 9

47

_1

1 2

0

1

14

1 5

1

30

0

2

27

60

-6 .62- 1 . 8 1

3.39

0.52

- 7 .35

4 88- 1 . 1 10 384.68

4.43

* Number exceeding 95th percentile value (0 41 /xg/100 ml) of three comparison townst Student 's t test comparing smelter town mean with mean of all comparison towns.t Number of samples with value below detection limit of test.

TABLE 8

Arsenic con centrations m drinking water in selected

Arizona towns

TownWater arsenic concentration

(rag/liter)

TABLB 9

Relationship of bottled water use to urinary arseniclevel, Ajo, Arizona

Geometric

AjoDouglasHaydenMiamiMorenciSaffordSan Manuel

0.070 02

<0.010 01

<0.01<0.01<0.01

Bottled Water Use No ofchUdren

(/ig/hter)

The single exception appears to have beenAjo, Arizona, where arsenic in water madean important contribution to exposure.

Juxtaposition of data from this and pre-vious smelter studies suggests that themost important factors related to heavymetal absorption by children living nearsmelters are emission characteristics andproximity of residences to the smelter.

Emission characteristics. The quantity

of ore processed and its relative concentra-tion of heavy metals are crucial determi-na nt s of the amo unt of heavy m etals emit-ted from smelters. The high arsenic con-tent of ore processed in Anaconda, Mon-

NoneLittle (drinking only)Moderate (drinking and occa-

sional other uses)Heavy (drinking, cooking,

school)

Total

22

32

1 2

1 0

76

1 1 5

77

60

48

tana, and Tacoma, Washington, as com-pared with the relatively low arsenic con-tent of ore mined in Arizona, may wellaccount for the differences in hair andurine arsenic levels in children in thesetowns. Varying amounts of cadmium andlead in ore refined in different zinc andlead smelters may account for similar dif-

ferences.Proximity to the smelter. Data from the

current study on the relationship betweenresidential distance from the smelter andhair contamination with lead, cadmium,


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A N A T I O N W I D E S U R V E Y O F H E A V Y M E T A L A B S O R P T I O N 271

2oou

s

4 0 -

30 -

2

| 20

u

a.

10-

II I

05 10 15 20 25 30

DISTANCE FROM SMELTER (KILOMETERS)

FIGURE 1. Hair cadmium levels by distance of home from plan t, P alme rton, PA, 1 975

and arsenic, as well as data from otherstudies (1-3), indicate that the closer achild's home is to th e sm elter the g rea ter ishis exposure to and absorption of sub-stances emitted by the smelter . Thus,towns with many people living near thesmelter would be expected to have moreindividuals with significant heavy metalexposure than towns with fewer people re-siding nearby. Stack height and local cli-

matic conditions also influence distribu-tion of smelter emissions.

The biologic significance of chronic in-creased absorption of lead, cadmium, andarse nic by children in a com mu nity is diffi-cult to assess. M ore is kno wn of th e effectsof low-level lead exposure than of the ef-fects of cadmium and arsenic exposure.Anemia and subclinical neuropathy havebeen associated with exposure to lead ne ar

primary lead smelters. In the currentstud y very few children were found to ha veblood lead levels high enough to be associ-ated with hematologic or neurologic toxic-ity.

The manifestations of chronic cadmiumtoxicity that have been observed in rela-tion to occupational exposure are primar-ily renal (22) and pulmonary (23). Renaltubu lar dam age, associated with increasedlevels in urine of a low-molecular-weightprotein, beta2 microglobulin, is the earli-est toxic manifestation of excessive cad-mium exposure (24). Reports from indus-trial sources of cadmium nephropathy are

difficult to relate to the lower-level com-munity exposures described in the currentreport. Chronic cadmium intoxication inchildren ha s not been previously describedand req uires further study before any con-clusions can be m ade concerning its toxic-ity.

A similar dearth of knowledge exists onhealth effects in children of chronic low-level exposure to arsenic. Dermatologic(25), hem atologic (26), neurologic (27), andneoplastic (28) sequelae have followed oc-cupational and environm ental exposure toarsenic and its compounds. As in the caseof cadm ium , extrap olation of thes e data to


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272 BAKER ET AL

the exposure conditions under study wouldbe unwise because of the dissimilarity ofthe population studied and the nature ofthe exposure. Further study is needed to

asse ss th e toxicity of chronic arsenic expo-sure in children, particularly when expo-sure is preventable .

The da ta from th is study on heavy m etalconcentrations in children from communi-ties without smelters may be comparedwith data from other epidemiologic evalu-ations of levels of lead, arsenic, and cad-m ium in "unexposed" children. Studies ofchildren without exposure to industriallead sources in Ireland (29), New Zealand(30), an d in urb an (31 , 32) and ru ra l (33)areas of the United States found averagehair arsenic levels of 0.12-0.4 ppm, haircadmium levels of 0.88-0.9 ppm, and hairlead levels of 7.6-24 ppm. These levelscom pare closely with m ean ha ir levels ofarsenic (0.1 ppm), cadm ium (1.1 ppm), andlead (13.0 ppm) seen in control children inthe current study. Studies of unexposedchildren in Utah (34), Idaho (2), and GreatBritain (35) showed mean levels of lead inblood of 11.7-21.9 /xg/100 ml and cadmiumin blood of 0.49-0.66 ^g/100 ml. Mean lev-els in the current study were 16.6 /tg/100ml for blood lead and 0.2 /*g/100 ml forblood cadmium concentrations.

The results of this study are reassuringin that none of the communities surveyedwere found to have a problem of heavy

m etal absorption as serious as tha t in Kel-logg, Idaho, where 98 per cent of one tonine-year-old children living within 1.6km of the smelter stack had blood leadlev els of 2:40 yxg/100 ml an d 22 per cent hadlevels of 2:80 p,g/100 ml and required che-lation therapy. On the other hand, thesedata are hardly cause for complacency;chronic absorption of arsenic, lead, andcadmium by persons living near smelters,particularly by such potentially vulnera-ble group s as young children and pregna ntwomen, may be causing undetected, latentdisease that will become manifest in thefuture. It would seem reasonable to carryout follow-up investigations to evaluate

the toxicity of chronic low-level commu-nity exposure to arsenic and cadmium.However, it would also seem prudent,even before the results of such studies be-

come available, to reduce to a minimumthe exposure of communities to the toxicmetallic emissions of smelters.

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Documents

A Nationwide Survey of Heavy Metal Absorption in Children