Journal of Radioanalytical and Nuclear Chemistry, Articles, 89/2 (1985J 561-5 70

N u c l e a r M e t h o d s in E n v i r o n m e n t a l S c i e n c e

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

D I F F E R E N T L E V E L S O F P O L L U T I O N

I. OBRUSNfK*, O. SKRIVANEK,** M. UMLAUFOVA**, V. HOVORKA***

*Nuclear Research Institute, 250 68 l~d (Czechoslovakia) **District Health Centre, Chomutov (Czechoslovakia)

***District Health Centre, Jind~ichftv Hradec (Czechoslovakia)

(Received February 8, 1984)

Instrumental neutron activation analysis has been performed on human head hair of newborns and mothers sampled in two areas with a different level of environmental exposure. The group of neonates from the exposed area (polluted by thermal power plants burning brown coal and by chemical industry) has exhibited higher levels of several trace elements in hak, e.g. Se, Zn, Hg and Sb in comparison with the control group. Moreover, the mean concentrations of Se, Hg, Zn and Br in neonate hair have been found to be higher than in mothers hair. Although the study revealed statistically significant differences in the composition of neonate hair .,sampled in areas with different levels of environmental exposure, the differences are relatively small. Only a thorough long-term study both with environmental and medical observations can prove a direct connection of the elevated levels of some trace elements in neonate hair with the higher frequency of mental diseases of children living in the exposed area.

Introduction

Human hair is a unique tissue which, owing to its growth, reflects b o t h

the biomedical and environmental history of an individual. I t has beert

demonstrated that hair can be used as a fairly good monitor in environmental,

epidemiological and biomedical studies. 1 t2 Hair has a proper ty to retain trace

elements. Therefore, the concentrations o f most toxic and other trace elements

are at least an order of magnitude higher than those in body fluids or other

easily accessible tissues. 3~

Elemental concentrations in hair provide a measure o f the average blood level corresponding to several month 's growth period. Moreover, hair can be usually

analyzed with lesser interference than blood. The above mentioned properties o f

17" 561

I. OBRUSN/K et al.: NEUTRON ACTIVATION ANALYSIS

hair together with relatively simple sampling contribute to an application of human hair for assesing exposure of population groups to environmental pollutants.

It was found from long-term observations that children born and living in the heavily polluted area "A" (polluted by thermal power plants burning a local brown coal and by chemical industry) have more frequently various kinds of mental diseases comparing with children living in a relatively clean "non-polluted" area "B". It is possible that the higher incidence of the diseases can be caused by a higher level of the environmental exposure in area "A".

To study this problem an analysis of hair of neonates from both areas have been carded out and, in the second part of this study, the samples of maternal hair have been analyzed as well. Neonatal hair can be a good indicator of environmental exposure through endogenous mechanism as an external contamina- tion of this type of hair is very low. It is supposed that a metal content in neo- natal hair is due entirely to placental transfer from the mother. +

In order to study elemental composition of both the neoiqatal and maternal hair instrumental neutron activation analysis (INAA) has been used. This analytical method is highly sensitive for the determination of many elements and the influence of blank on the INAA results is often negligible. Other typical features of INAA are multielement determination capability, good reproducibility and instrumental character of the method, s

Experimental

Samples and standards

Scalp hair samples of the neonates from exposed and cnntrol areas were collected both in 1978 and 1979. Each group of hair samples consisted of 28 samples. Moreover, maternal scalp hair was also sampled in 1979,

The neonate hair samples were taken by cutting with a glass knife immediately after the birth. The maternal hair samples were cut by scissors and root ends of the sampled hair were cut off later (in the laboratory) by a glass knife.

To remove surface dirt and grease, the hair samples were washed according to the procedure recommended by the IAEA Advisory Group on Application of Nuclear Methods in Environmental Research, ~ The procedure consisted of washing with 25 ml of very pure acetone followed by three successive rinses with 25 ml of redistilled water and f'mally of washing with 25 ml of acetone. The contact time was 10 rain in each step. Afterwards, the samples were allowed to air-dry at room temperature.

562

I. OBRUSN~K et al.: NEUTRON ACTIVATION ANALYSIS

About 60-120 mg of the washed and dried hair was weighed and heat-sealed in clean polyethylene bags. Mixed standards for 20 elements (4-7 elements in each standard) sea/ed in polyethylene bags were routinely used. To avoid losses of mercury from the standard by volatilization the standard was stabilized by means of thiourea. 7

INAA procedure

The samples together with the standards were irradiated for 3 hours in the core of the WWR-S type nuclear reactor at Nuclear Research Institute in l~e~. at a thermal neutron flux of 2 �9 1013 n �9 cm -2 �9 s -1 .

Each sample was counted twice, 2-3 days and 20-25 days, respectively, after the end of irradiation. The gamma-ray spectrometer used consisted of two Ge(Li) coaxial detectors (I~IJV) coupled through Ortec linear electronics to two 100 MHz analog-to-digital converters CT 102 (Intertechnique). A 8192 (2 X 4096) channel computer-based analyzer Plurimat 20 (Intertechnique) was employed for storing and processing of the spectra from both detectors. The resolution of the system was 2.5 and 2.8 keV, respectively, and relative counting efficiences were 5 and 9%, all compared at the 1332 keV photopeak of 6~

The spectra were processed immediately on-line using a modifed version of a PRM O1C measurement program by means of a minicomputer Multi-8 (Intertechnique) built-in the system. The peaks of interest were corrected for the decay and pile-up losses, where necessary, by the program.

The concentrations of Cu and Hg were corrected for interference contributions prior the calculation of the final results. The concentration data were then evaluated by means of programs written in BASIC language (frequency histograms, calculation of arithmetic and geometric means, ranges, medians etc.).

Results and discussion

The elements giving rise to medium half-life nuclides as As, Au, Br, Cu, K, La and Na have been determined by the first counting. The second measurement has been used for the determination of the elements forming long-lived nuclides, e.g. Co, Hg, Sb, Se and Zn. The gamma-ray spectrum from the second counting (neonate hair, exposed group "A") is shown in Fig. 1.

563

I. OBRUSNIK et al.: NEUTRON ACTIVATION ANALYSIS

.-~ Tc

. c u

m

u

5

o o

~ , o

o

c c

~ t3 u = . a

t ~

1 2

1

~_ ., Q

3 xlO 3 channel number

Fig. 1. Gamma-ray spectrum of a neonatal hair sample (group "A") recorded 23 days after irradiation (sample weight 80 mg, tirrad. = 3 hrs, tcount. = 100 rain)

Table 1 Concentrations of trace elements in hair of neonates from exposed and

control groups (28 samples in each group, year 1979)

Element Range, ppm Arithmetic mean, Geometric mean,

ppm ppm

Median, ppm

Exposed ~.oup "A"

Au 0.0036-0.23 0.034 • 0.055 0.017

Br 1.24-19.8 5.02 • 4.1 3.94

Cu 6.2-12.3 9.41 -+ 1.34 9.31

Hg 0.67-6.3 1.53 • 1.03 1.37

La 0.009-0.21 0.035 + 0.045 0.021

Na 5.4-45.1 14.7 • 9.6 12.3

Sb 0.04-0.54 0.15 • 0.15 0.I0

Se 0.45-1.32 0.87 • 0.20 0.85

Zn 128-366 235 • 54 229

Control group "B"

Au 0.0017-0.023 0.009 + 0.005 0.007

Br 0 .93-103 18.4 • 22.1 10.1

Cu 6.5-11.3 8.6 + 1.12 8.54

Hg 0.67-5.4 1.37 • 0.92 1.21

La 0.005--0.39 0.032 • 0.08 0.014

Ha 3 . 4 - 2 1 9.6 -,- 5.7 8.2

Sb 0.02-1.43 0.13 • 0.27 0.074

Se 0.38"1.02 0.69 • 0.15 0.67

Zn 172-264 202 • 19.4 201

X 2.9 x. 2.0

x. 1.2

x 1.5

x 2.5

x 1.8

x 2.3

.x. 1.3

.x 1.2

X 1.8

)~ 3.2

X. 1.1 X: 1.6

X. 2.7

X 1.8

2.4

:X 1.3

.x 1.1

0.015

3.26

9.55

1.31

0.013

11.3

0.06

0.89

221

0.007

9.4

8.4

1.13

0.010

8.0

0.050

0.67

201

I. OBRUSNIK et al.: NEUTRON ACTIVATION ANALYSIS

Table 2 Concentrations of trace elements in hair of neonates from exposed anti

control groups (56 samples in each group, years 1978 + 1979)

Element Range, ppm Arithmetic mean: Geometric mean, Median, ppm ppm ppm

Exposed group "A" Br 1.2-20 5.14 • 3.35 4.31 X. 1.8 4.20 Cu 5.2-12 3 8.06 • 1.77 7.87 X. 1.2 7.80 Hg 0.62-6.3 1.32 • 0.87 1.18 .X. 1.5 1.12 Na 5.4-193 21.8 • 27 16.1 X. 2.0 15 Sb 0.04-3.5 0.26 • 0.51 0.14 X 2.8 0.10 Se 0.45-1.32 0.86 • 0.17 0.84 X.. 1.2 0.86 Zn 128-389 242 • 58 235 X 1.3 231

Control group "B" Br 0.93-156 25.7 • 31 14.8 X 3.0 14.8 Cu 6.3-12.2 8.69 -+ 1.2 8.6 ~. 1.1 8.5 Hg 0.24-5.4 1.0 • 0.77 0.83 .X 1.8 0.79 Na 1.50-162 19.8 • 30.6 11.4 .X 2.6 9.7 Sb 0.02-1.43 0.12 -+ 0.24 0.07 ~. 2.4 0.06 Se 0.38-1.02 0.67 • 0,15 0.65 ~. 1.3 0.64 Zn 160-264 207 • 21 206 X 1.1 205

The presentation o f the analytical data summarized in Tables 1 - 3 includes

descriptive statistics as the arithmetic and geometric means with their standard

deviations, the range and the median. The mean values have been calculated by

using the data for all samples in each group including samples with concentrations

below the detection limit o f the INAA method used (upper limit values have been used in that case).

Table 1 contains the concentrations of the elements found in hair o f neonates

from the exposed and control areas collected in 1979 (28 samples in each group).

Table 2 summarizes the INAA results o f neonatal hair collected in 1978 and 1979

(56 samples in each group). Similarly, Table 3 contains the concentration data

of maternal hair sampled in both areas in 1979 (28 samples in each group).

Histograms showing the distribution of concentrations of the environmentally

important elements (Se, Hg, Zn and Cu) in neonatal hair (1978 and 1979

together) are plotted in Figs 2 and 3. The shape of the frequency curve is

mostly distorted in the case o f neonatal hair collected in exposed area "A",

565

I. OBRUSN[K et al.: NEUTRON ACTIVATION ANALYSIS

&

3 0 - -

g o

2O

10

0 &4

t - ' l

..J

/ i

i

t ,=q =Ci 1 018 1.2 1,6

Se content ) ppm

i

3O

o" I I r

1

10 r j ,

o l , ~ , IF] 0 0.8 1.6 2.4 32

Hg content ) ppm

Fig. 2. Histogram showing the distribution of Se and Hg concentrations in neonatal hair with respect to the different level of environmental exposure; - - exposed area "A" - - - control area "B"

40--

g

30

2(]

IC

160

r I r I

,, . J

i

1 I

,,

] t 240 320 400

Zn content 7 ppm

40

ma

g s

30

20

r - i

t-.J i

1 1 I 1 T | I ~ . 6 8 10 12 14

Cu Content ~ ppm

Fig. 3. Histogram sho* i ng the distr ibution o f Zn and Cu concentra t ions in neonata l hair wi th respect to the different level o f envi ronmenta l exposure; - - exposed area " A " - - - control area "B"

566

I. OBRUSN/K et aL: NEUTRON ACTIVATION ANALYSIS

Table 3 Concentrations of trace elements in hair of mothers from

exposed and eontro ! groups (28 samples in each group, year 1979)

Element Range, ppm Arithmetic, mean Geometric mean, Median, ppm ppm ppm

Exposed group "A" As 0.03-1,04 0.28 -+ 0.24 0.19 .X. 2.5 0.20

Au 0.005-0.54 0.055 -+ 0,t0 0.03~ x 2.6 0.028

Br 0.22-4.43 1.04 -+ 0.90 0.83 X. 1.9 0.76 Co 0.01-0.58 0.052 -+ 0.11 0.032 X 2.0 0.030

Cu 6.6-39 12.95 -+ 6.4 12.0 ..X 1.4 11.6

Hg 0.21-3.2 0.90 -+ 0.64 0.76 X 1.7 0.70 K 3.5"179 29.3 ~ 43.9 15.1 ~ 2.9 10.0 La 0.007-0.2 0.04 +- 0.05 0.024 X 2.7 0.019

Na 4.1-976 74.6 • 196 17.3 :X 4.3 9.8

Sb 0,0454).61 0.12 ~ 0.11 0.09 .X 1.8 0.080

Se 0.2-0.83 0.39 -+ 0.13 0.37 ~. 1.3 0.36 Zn 77-445 187 +- 73 176 X 1.4 168

Control group "13" Au 0.0044.08 0.081 -+ 0.21 0.026 X 3.8 0.024 Br 0.4t-42 3.64 -+ 8.4 1.54 X 2.8 1.11

Co 0.02-0.15 0.038 -+ 0.03 0.033 .X 1.6 0,023 Cu 7.9-19.9 11.2 -+ 3.1 10.9 X 1.3 10.0

Hg 0.35-2.03 0.84 -+ 0.40 0.77 X. 1.6 0.73

K 5.1-36 12.7 -+ 7.5 11.1 ~. 1.7 9.3

La 0.006-0.87 0.066 -+ 0.17 0.024 ~. 3.1 0.020

Na 2.7-43.5 14.0 • 10.0 10.9 ~. 2.1 13.4

Sb 0.05-0.54 0.19 ~ 0.12 0.16 ~. 1.8 0.20 Se 0.2-0.60 0.39 -+ 0.1 0 .38. x. 1.3 0.39

Zn 93-503 183 • 71 175 X 1.3 167

whereas the shape of this curve plotted for the control group is much closer to

a log-normal :listribution.

The mean values of the elemental concentrations in the hair of both the

neonates and mothers have been examined for the presence of differences by

means of the t-test. 8 The results of this testing for the elements Se, Zn, Br, Hg,

Cu and Sb are shown in Table 4.

567

I. OBRUSN~( et al.: NEUTRON ACTIVATION ANALYSIS

Table 4

Testing of the differences between the mean trace element

concentrations in hair samples

Element Relation Significance Groups compared level

Se, Zn c A > c B 0.01 Neonates "A" vs. neonates "B"* Br c B > c A 0.01 Hg c A > e B 0.05 Cu c B > c A 0.05 Sb c A > e B 0.1

Sb c B > c A 0.05 Br e B > c A 0.1

Hg, Cu, Se, Zn N.S.D.

Se, Hg, Zn, Br c N > c M 0.01 Cu c M > e N 0.01 Sb N.S.D.

Se, Hg, Br c N > e M 0.01 Cu c M > e N 0.01

Sb, Zn N.S.D.

Mothers "A" vs. mothers "B '~

Neonates "A" vs. mothers "A"

Neonates "B" vs. mother "B"

*See values in Table 2 (1978 and 1979). Notes: c A, c B . . . elemental concentration in hair collected in area A or B, respectively,

CN, c M. .. elemental concentration in hair of neonates or mothers, respectively. N. S. D. = no significant difference.

Table 5 contains the results of calculations of possible correlations between

elemental concentrations found in neonatal and maternal hair collected in both

areas studied.

It can be concluded from the results that the mean concentrations of Se, Zn

and also of Hg and Sb in neonatal hair from exposed group A are significantly

higher than those of control group "B" (Tables 1, 2 and 4). This feature can

also be seen in Figs 2 and 3. Even though the statistically significant differences

especially in the case of Se and Hg can be regarded important, it is necessary to

stress that the differences are relatively small and, therefore, do not provide

evidence that the exposed group of neonates A may not be regarded as normal )

On the other hand, neonatal hair samples collected in control area "B" show

higher mean concentrations of Br and Cu. The difference is rather high in the

568

[. OBRUSN[K et al.: NEUTRON ACTIVATION ANALYSIS

Table 5 Interrelationship among certain trace elements in neonatal

and maternal hair

Exposed group "A" Control group "B"

Pair of elements Correlation Pair of elements Correlation

Br(N)/Cu(M) 0 ' .477 Se(N)/Zn(M) 0~522 Hg(N)/Hg(M) 0 . 4 7 3 Se(N)/Se(M) 0.241 Br(N)/Br(M) 0.369 Se(N)/Br(M) 0.226 Cu(N)/Br(M) 0.167 I-Ig(N)/Br(M) 0.214 Cu(N)/Cu(M) 0.164 Zn(N)/Se(M) 0.181 Br(N)/Zn(M) 0.162 Br(N)/Se(M) 0.179

Cu(N)/Cu(M) 0.166

(N) neonates; (M) mothers.

ease of Br and can hardly be explained - probably some specific Br contamina-

tion occurs during sampling of neonatal hair in control area "B".

The differences in the composition of maternal hair samples collected in both

areas are much smaller than in the case of neonates. Of particular interest is the

finding that the concentration of As in maternal hair of control group "B" has

been mostly below the detection limit of the INAA procedure (0:05 ppm). It

can be associated with a lower environmental exposure in this area.

The results show another interesting feature - the concentrations of Se, Hg,

Zn and Br in hair of neonates are higher than those of their mothers in both

areas studied. On the other hand, the concentration of copper is higher in

maternal hair than in the neonatal hair samples. Arsenic has not been detected by INAA in neonatal hair from both areas, probably a transfer of this element

through placenta is difficult.

Interrelationships summarized in Table 5 show that Hg and Br concentrations in neonatal hair (exposed group "A") are related to the content of those elements in

maternal hair. Also Br in neonatal hair [Br(N)] shows rather good correlation with Cu concentration in maternal hair [Cu(M)]. In accordance with AKASHI 9 we have not

found a correlation between Se and Hg. Similarly, the content of Se(N) is correlated with Zn(M), Se(M) and Br(M) in the control area "B".

569

I. OBRUSNIK et al.: NEUTRON ACTIVATION ANALYSIS

Conclusion

The study of the composition of neonatal and maternal hair collected in areas with a different level of environmental exposure by means of INAA has proved

to be useful. The results have shown several interesting aspects, e.g. significant

differences in the composition of neonatal hair samples (especially Se and Hg)

and also higher concentrations of Se, Hg, Zn and Br in neonatal hair comparing

with the hair samples collected from mothers.

Even though the study revealed statistically significant differences in the

composition of neonatal hair samples taken in the areas with different levels of

environmental exposure, the differences are relatively small. Therefore, a direct connection of elevated levels of some elements in neonatal hair with the higher

frequency of mental diseases of children from the exposed area cannot be

proved as yet. A long-term study, both with environmental and medical observa-

tion, will be needed in this case.

References

1. YU. S. RYABUKHIN, J. Radioanal. Chem., 60 (1980) 7. 2. V. VALKOVIC, Trace Elements in Human Hair, Garland Publishing, New York, 1977. 3. G.V. IYENGAR, W. E. KOLLMER, H. J. M. BOWEN, The Elemental Composition of Human

Tissu6s and Body Fluids, Verlag Chemie, Weinheim, 1978. 4. N. BAUMSLAG, D. YEAGER, L. LEVIN, H. G. PETERING, Arch. Environ. Health, 29 (1974)

186. 5. I. OBRUSNIK, Chem. listy, 76 (1982) 805. 6. YU. S. RYABUKHIN (Ed.), Activation Analysis of Hair as an Indicator of Contamination of

Man by Environmental Trace Element Pollutants, IAEA, RL[50, Vienna, 1978. 7. T. TAKEUCHI, Improvements and Applications of Computer Assisted NAA Using the

Monostandard Method, Osaka, 1977. 8. I, W. BURR, Applied Statistical Methods, Academic Press, New York, 1974, p. 228. 9. J. AKASHI, A. IMAHORI, I. FUKUSHIMA, Radioisotopes (Tokyo), 30 (1981) 9.

570