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Trace element concentration in hair of the Bangladeshi population
lnlcrnefionol Jowncll of Applied Rudisrion und laornpvs Vol. 31. pp. 527 to 533 0 Pergamon Press Ltd 1980. Printed in Great Britain
Trace Element Concentration in Hair of the Bangladeshi Population * M. HUSAIN,
M. KHALIQUZZAMAN, M. ABDULLAH, I. AHMED and A. H. KHAN?
Atomic Energy Centre, P.O. Box 164, Dacca, Bangladesh (Received 15 January 1980; in revisedform 21 March 1980) Trace element concentrations in hair of an adult population in Bangladesh have been measured. The sample group was formed of 102 subjects randomly selected from a working community of about five hundred adults. All the hair samples were analyzed by the external beam PIXE method. In this analysis, 2-MeV proton beams with c 30 nA intensity were used for the irradiation of targets prepared as l-mm thick pellets. The concentration of twelve elements has been determined by comparison with a calibration obtained from the NBS orchard leaves. The results from the present study have been compared with the values recently reported in literatures.
Introduction THE POLLUTION of the biosphere by trace elements,
especially by heavy metals, is a global concern of the modern time. In a recent study at BAI-IELLE,'~) it has been indicated that in future the quality of human life would be most affected by the environmental stress due to heavy metal contaminations. At present it is second only to pesticides in this respect. All pollutions in the living environment ultimately affect man. So, the study of trace element pollution in man deserves the most urgent attention. It is also important to have a knowledge of the normal levels of trace elements in man so that any deviation from it can be monitored. It is to these ends that considerable efforts are being made all over the world to determine trace element contents in different human tissues and body fluids. US’) Of all human tissues, the head hair has been identified to be most suitable”) for the analysis of many trace elements in man, firstly because it is easily accessible to experimentation for analysis. Secondly, during the growth period, hair being exposed to circulating blood, lymph and extracellular fluids, keeps a continuous record of the changes of the trace element concentrations in the body.‘3.4) However, if the data on the trace element contents of hair are to be used as an indication of the body burden, the external contamination of hair is to be taken into account. In that case, hair data are to be supplemented by those of tissues and body fluids. Realizing the importance of trace element analysis of hair and the availability of powerful methods like NNA, AAS, PiXE, etc., the IAEA started an inter* This research was supported in part by the International Atomic Energy Agency, Vienna, under the Contract No. 2136/RB. t Author to whom all correspondence should be addressed.
nationally coordinated study programme on this subject. The present study is a part of that programme. In this study, all the hair samples were analyzed by the Proton-induced X-ray Emission (PIXE) method. In all, 102 samples from an adult population in Bangladesh were analyzed. The results on the contents of 12 elements that were possible to be detected with the PIXE method are reported here.
Experimental Each hair sample (- 5 g) was collected from different areas of head with a clean stainless steel clipping scissors. According to the prescribed procedure,‘3’ the samples were washed twice with acetone, three times with double distilled water and finally once with acetone. The washed samples were air dried for 24 h in a clean room A known quantity of each dry sample was charred at 180°C for 1 h in a Pyrex beaker, in order to easily powder the material. The charred sample after cooling and weighing was ground to powder with an aluminium carbide mortar and pestle. Before this operation, a sample of chromatographic grade cellulose powder (Whatman) was ground in the mortar for blank correction, if any. From the powdered material of hair, 50-mg pellets, 7 mm dia. and 1 mm thick, were prepared with a graduated stainless steel hand-press pellet maker (Perkin-Elmer). The pellets were mounted in 35 mm slide frames with adhesive tape and preserved in a desiccator until irradiation. In this investigation, the external beam PIXE method was used to determine trace element contents in hair. The details of the method have been described elsewhere.‘5-7) A schematic diagram of the experimental setup is given in Fig. 1. Kapton foils of 1.12 mg cm-* thickness instead of Be were used as the proton exit windows. Proton beams of nominal
527 *.n.,.3119
-A
M. Husain et al.
528
Scattered
beam 35 mm
Beom --+
NOT
TO
SCALE
FIG. 1. A schematic diagram of the PIXE experimental setup.
of 2.5 MeV from the 3 MeV Van de Graaff accelerator at the Atomic Energy Centre, Dacca (AECD) were used for the irradiation of the targets. After energy loss in the exit window and the air path, the beam energy on the target was about 2 MeV. The targets were placed at 45°C with respect to the beam direction. The beam spot at the exit window was 4 mm. This gave an irradiation spot on the target well within the pellet diameter. The irradiation current was about 30nA. Under these beam conditions, a reasonable counting rate was achieved. The integrated current for each irradiation was 20 pC. Characteristic X-rays were detected with a 30 mm’ Si(Li) detector (Ortec). A 44 mg cm-* plastic absorber energy
was used to reduce the argon background in air. The pulses after amplification were analyzed with a 4096 channel Canberra Analyzer. The data reduction was done manually. Corrections for the overlapping peaks were made from the K,/K, ratios measured separately under identical conditions using cellulose targets doped with the element concerned. A typical X-ray spectrum of a hair sample is illustrated in Fig. 2.
Results and Discussion Concentration calibration and the sensitivity of the method
For trace element concentrations in hair, the PIXE method was calibrated with the NBS orchard leaves
I04 HUMAN = 2
EP Q I03
HEAD
HAIR
MeV
= 20uC
-
I
L 0
1
I
I
5
IO
15
X -
RAY
ENERGY
(k eV)
FIG. 2. An X-ray spectrum from a hair sample irradiated in air as l-mm-thick pellet using a 44 mg cm- * plastic absorber.
529
Trace element concentration in hair
E, = 2.0 ABSORBER
MeV - 44 mg/ cm2
DET. GEOM. =0’018
IS
20
25
30
35
PLASTIC
Sr
40
45
ATOMIC NUMBER FIG. 3. The concentration
calibration curve obtained from the NBS orchard leaves standard for a 40 pC irradiation.
(SRM 1571) standard. The calibration curve shown in Fig. 3, is the X-ray yield per ppm per microcoulomb vs the atomic number of the element. As the NBS recommends to use at least 250 mg of the standard in any experiment, the average peak areas obtained from the irradiation of several 50 mg pellets were used to construct this yield curve. The concentration of the element i in the sample was then simply obtained from Pm
KTW = - QXi 9 at constant geometry
where Y, is the X-ray yield of the element in the sample, T is the dead time correction factor, Q is the integrated charge (PC), Xi is the calibration factor and W is the dry weight factor of the sample. It has been mentioned before that the samples were charred at 180°C to make it easy to grind them to fine powder. In doing so, it was believed that at this low temperature of charring, there would not be any appreciable loss of trace elements. The average weight loss due to charring was found to be 26 k 4%. However, individual weight loss was used in the calculation of concentrations. The blank correction was found to be negligible. The sample homogeneity was tested by irradiating several pellets from the same ma-
terial and it was found within 4%. The geometry variation due to sample positioning was negligible. The applicability of the calibration curve in Fig. 3 for analyzing trace elements in other biological matrices such as hair has been discussed in detail elsewhere.“) In view of the X-ray yields obtained in a number of light element matrices widely varying in proportions of the major elements (H, C, N, 0, etc.), it was observed that such calibrations are universally valid for all biological matrices. The systematic deviation of the curve for different matrices was estimated to be less than 15%. This can, however, be further reduced, if the concentration of the major elements in a given biological matrix is known. The minimum detection limits (MDL) of different elements in the hair matrix are given in Table 1. The MDL of an element, from the consideration of statistical errors in counting, was defined as the amount which would yield an X-ray intensity at least equal to 3a of the background under the peak taken in an interval equal to the FWHM of the peak. For a 20 PC irradiation, it was about 0.3 ppm in the region of iron. Distribution of trace elements in hair
In all, 102 samples were analyzed. The subjects were randomly chosen from about 500 employees of the AECD. The age range of the population group
M. Husain et al.
530 TABLE
1. Minimum detection limit (MDL) in hair matrix for 20 PC irradiation
Element
Atomic No.
MDL in ppm (pg g- ‘)
K F: Cr
19 20 22 24
9.0 3.28 0.90 0.52
Mn Fe Ni CU Zn
25 26 28 29 30
0.41 0.31 0.34 0.33 0.40
Br Sr Pb
35 38 82
0.44 0.76 0.71
surveyed in this study was 2&55 y, the maximum frequency being at 27 y. With the present method, under the experimental conditions mentioned before, twelve elements were found to have concentrations above the detection limits in hair. A summary of these results is given in Table 2. In the calculation of the mean, the data points which do not form a part of the close distribution in the plot of frequency vs logarithm of concentration were not considered. The values of the ranges shown in Table 2 also refer to the close distribution. The arithmetic and the geometric mean for each element was calculated by considering only the data above the background. The calculation of mean values by including the samples below the background, from the consideration of an assumed Gaussian distribution, could not be done, as the distributions obtained were not well behaved. The mean values shown here are, therefore, artificially high for those elements where a fraction of the samples was found to have concentration below the background level. Similarly, in the calculation of the median, only those data points above the background, which form close distribution in log normal vs frequency plot, were considered. The frequency distribution of the concentration of different elements is shown in Fig. 4. The mean and the median in Fig. 4 correspond to the close log distribution as discussed earlier. The uncertainty shown in the case of arithmetic mean (AM) is the standard deviation and in the case of the geometric mean (GM), it is the antilog of standard deviation of the log of concentration. The uncertainties in the median are due to counting statistics. A comparison of our results with those reported from other countries@*@ is shown in Table 2. The data mentioned under reference 3 also include those recently published in the IAEA proceeding”’ and here the range means the range of arithmetic means for different groups. From this comparison, it can be observed that the arithmetic mean of the concentrations of the elements, K, Ca, Cr, Mn, Fe and Ni, is in agreement with similar data found in other countries. The K content of hair (48.4 f 30.1 ppm) from
this study is, however, significantly higher than those in India and Japan”’ (e.g. India: 16.8 f 10.5 ppm, Japan: 18.7 f 23 ppm). The concentration of Cu in Bangladeshi population is lower almost by 40% than the lowest value (AM) reported for this element in hair, while that of Zn (141 f 34 ppm), mostly corresponds to the lowest value of different arithmetic means. HAMMERet ~1.‘~’ have observed that the levels of essential trace elements such as Cu and Zn in hair are not related to environmental exposures. The low contents of Cu and Zn from the present study may thus be related to other factors as diets deficient in these two elements. Such an observation has been reported by McBEAN(‘O)for Zn deficient diets. For some trace elements (e.g. Ti, Sr), there are few published data to make any fruitful comparison. However, for normal JapaneseJ2) the Ti content in hair was found to be 11.7 + 7.0 ppm, with the range of 2.2-35 and IYENGERet df8’ compiled values in the range of 0.048-14ppm (AM) for three different groups. Compared to these results, we have found a range of ~1.5-6.1 with the mean of 3.2 + 1.4ppm. CHUANGand EMERY”‘) have reported a median value of < 20 ppm for Sr in head hair of eleven residents in Hong Kong. IYENGER et al. (*) have reported a range of 0.0460.92 for Sr. In this case, our value is 2.55 f 1.14 ppm with the range of 0.85-5.3 ppm. On the content of Pb in hair, reported results(*) have the range of 3-70 ppm (range of AM) for thirteen different groups. One Canadian study (quoted in @)) has reported values of Pb for rural population, in the range of 0.5-25 ppm with a median of 9.1 ppm while for the urban population, it was 0.5-35 ppm, the median being 15.3 ppm. These are rather high values compared to the results reported here (mean: 4.18 f 2.37 ppm, range: <0.91-11.2 ppm). HAMMERet ~1.‘~’observed that the variation in environmental exposure to human non-essential elements ‘such as Pb, Cd, etc. is reflected in hair. In this regard, the low contents of Pb and Br in head hair from the present study indicate that the population in the Dacca city is less exposed to environmental Pb and also Br, mostly from automobile exhaust and this bears the fact that the traffic concentration in the Dacca city is far less than what is seen in western cities. The peak for Pb L, line (10.55 keV) coincides with the As K, line. But in the absence of As K, line at 11.72 keV and from the consideration of the L,/L, ratio for Pb, the peak at 10.55 keV was considered to be purely due to Pb L, indicating the absence of As in the hair samples analyzed here. It may be noted that the detection limit for As in hair under the conditions of the present study is about 0.4 ppm. Conclusions The concentration of twelve elements (K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Sr and Pb) in the hair of an adult group of 102 individuals in Bangladesh is
102 30 102 102
100 49 96
K Ca Ti Cr Mn
Fe Ni cu Zn
Br Sr Pb
98 40 85
101 28 101 101
14 100 17 36 82
No. of samples in the close distribution
< 0.69-5.44 <0.85-5.32 <0.91-l 1.2
6.25-106.8 40.37-3.25 3.7-13.9 75.6277
< 10.3-149.9 217.7-1423 < 1.5-6.1
Range f + f + +
30.1 255 1.43 1.43 1.35
2.15 _+0.83 2.55 f 1.14 4.18 f 2.37
29.7 17.3 1.25 _+ f 0.72 6.78 _+ 1.60 141 + 34
48.4 652 3.20 2.45 2.33
AM*
1.70 1.75 1.25 1.25
1.88 1.48 1.55 1.85 1.81
2.0 x 1.48 2.30 x 1.58 3.56 $ 1.78
25.76 1.07 xx 6.60 x 137 4
5 x ; x &
GMt 40.1 605 2.91 2.1 1.96
This work
12.3 36.5 0.52 0.32 0.23
2.06 f 0.37 2.24 f 0.60 3.53 _+0.56
25.5 1.16 _+ f 0.34 0.23 6.79 _+0.32 134.4 f 1.10
41.0 f 609 f 2.57 f 2.04 f 1.90 +
Median1
AM
2.3-39 -
60-122s 1.01-18 1l-25.4 138-308
16.8-95 51B2650 -0.46-4.1 1.1-23
(raw4
Ref. 3
element concentration (pg g-i) in hair of normal population
AM Arithmetic mean. GM Geometric mean. * Uncertainties are the SD. t Uncertainties are the antilog of the standard deviation of the log of concentrations. $ Uncertainties are due to counting statistics. 8 For some of the studies, AM’s are not available.
77 102 17 40 92
Element
No. of
samples with detectable cont.
TABLE 2. Trace
GM
1.92-27 -
27-106 2.8-14 9.6-20.6 128-261
14.2-42 3863000 2.4-3.6 0.342.6 0.49-8.8
(range)
0.65-53.3 0.046-0.92 3-70
5-44.7 066.5 11-34 99450
146-3190 0.048-14 0.13-3.65 0.25-5.7
Range
Ref. 8
-
19 218
-
-
Weighted mean
gT
$ 2 z ;; ct. $ E
? 5 % 3 9
MEAN MEDIAN
CO
1. 255 36 5
PPM
652 609,
6
40
IO
2
e.Oloo
I
200
4
41(
6
20
r
I
4
_+ 0
217
PPM
distribution
2
25 5
MEDIAN
0406
297
MEAN
Fe
FIG. 4. Frequency
BK
IO
40 60 100 200
10
20
I
4
6
060
2 24:
10
4
6
20
in hair of a normal
IPPM)
,I4
PPM
2
2 55t
2
061
MEAN MEDIAN
Sr
02
72
6810
0 23
1 16,
PPM
4
MEDlAN
2
I 25 t.0
I
MEAN
NL
0406
I43
2 572052
3 20,
PPM
I
I
MEAN MEDIAN
Pb
2
_I
r
06
population.
IO
20
MEAN MEDIAN
C,
4
6
PPM
IO
4
20
6 610
4
6
10
4 I.92 2 37 3 532 0 56
2
2 45r I43 2 04fO 32
PPM
40
20
------I MEAN MEDIAN
TL
of trace elements
CONCENTRATION
6
34
3
JTlh_
040’6
0 I,
IO
20
41 Oi
MEDlAN
20
4+ 30 I
12 3
PPM
48
K
MEAN
40
20
Trace element concentration in hair
of trace elements, the application of the external beam PIXE method is found to be very convenient to obtain results within 15% accuracy. The mean (AM) concentrations of many of the elements analyzed in this study are found to be comparable to those reported in other countries. However, those of Cu, Zn, Br and Pb are signilkantly lower in Bangladesh than those in other countries and this may be related to dietary habits and other environmental factors such as small local sources of pollureported.
References
In such measurements
Acknowledgements-The authors wish to thank Dr A. A. Katsanos for his fruitful suggestions during the course of this work. The cooperation from Dr M. B. Zaman is recorded with gratitude. The technical assistance rendered by the staff members of the Technical Physics, Chemistry, Experimental Physics, Health Physics and the General Services Divisions of the AECD is gratefully acknowledged. Thanks are due to Mr A. H. M. Habibul Islam, Director, Atomic Energy Centre, Dacca, for his continued support for this research. The secretarial assistance from Mr A. F. Bhuyian is greatly appreciated.
533
Proc. Int. Symp. on Nuclear Life Sciences. IAEA, Vienna Proc. Int. Symp. on Nuclear L$e Sciences, IAEA, Vienna
Activation Analysis in the
(1972). Activation Analysis in the
(1978).
Report IAEA/RI/50 (1978). VALKOMCV. Trace Elements in Human Hair. Garland, New York (1977). KHANA. H., KHALIQUZZAMAN M., HUSAINM., AFJDULLAHM. and KATSANOS A. A. Nucl. Instrum. Meth. 165, 253 (1979).
KATSAN~SA. A., XENOULISA., HADJIANTONIOU A. and FINK R. W. Nucl. Instrum. Meth. 137, 119 (1976). KHALIQUZZAMAN M., ZAMANM. B. and KHAN A. H. (to be published). IYENC~ER G. V., KOLLMENW. E. and BOWENH. J. M. The Elemental Composition ofHuman Tissues and Body Fluids. Verlag Chemie, Weinheim, New York (1978). 9. HAMMERD. I., FINKLEAJ. F., HENDRICKSR. H. and SHY C. M. Am. J. Epidemiol. 93, 84 (1971). Ifi MCBEANL. D., MAHMIJGJI M., REINHOLDJ. G. and 1~. HALSTEDJ. A. Am. J. Clin. Nutrition 24, 505 (1971). 11. CHIJANG L. S. and EMERGYJ. F. J. radioanalyt. Chem. 45, 169 (1978).
Trace Element Concentration in Hair of the Bangladeshi Population * M. HUSAIN,
M. KHALIQUZZAMAN, M. ABDULLAH, I. AHMED and A. H. KHAN?
Atomic Energy Centre, P.O. Box 164, Dacca, Bangladesh (Received 15 January 1980; in revisedform 21 March 1980) Trace element concentrations in hair of an adult population in Bangladesh have been measured. The sample group was formed of 102 subjects randomly selected from a working community of about five hundred adults. All the hair samples were analyzed by the external beam PIXE method. In this analysis, 2-MeV proton beams with c 30 nA intensity were used for the irradiation of targets prepared as l-mm thick pellets. The concentration of twelve elements has been determined by comparison with a calibration obtained from the NBS orchard leaves. The results from the present study have been compared with the values recently reported in literatures.
Introduction THE POLLUTION of the biosphere by trace elements,
especially by heavy metals, is a global concern of the modern time. In a recent study at BAI-IELLE,'~) it has been indicated that in future the quality of human life would be most affected by the environmental stress due to heavy metal contaminations. At present it is second only to pesticides in this respect. All pollutions in the living environment ultimately affect man. So, the study of trace element pollution in man deserves the most urgent attention. It is also important to have a knowledge of the normal levels of trace elements in man so that any deviation from it can be monitored. It is to these ends that considerable efforts are being made all over the world to determine trace element contents in different human tissues and body fluids. US’) Of all human tissues, the head hair has been identified to be most suitable”) for the analysis of many trace elements in man, firstly because it is easily accessible to experimentation for analysis. Secondly, during the growth period, hair being exposed to circulating blood, lymph and extracellular fluids, keeps a continuous record of the changes of the trace element concentrations in the body.‘3.4) However, if the data on the trace element contents of hair are to be used as an indication of the body burden, the external contamination of hair is to be taken into account. In that case, hair data are to be supplemented by those of tissues and body fluids. Realizing the importance of trace element analysis of hair and the availability of powerful methods like NNA, AAS, PiXE, etc., the IAEA started an inter* This research was supported in part by the International Atomic Energy Agency, Vienna, under the Contract No. 2136/RB. t Author to whom all correspondence should be addressed.
nationally coordinated study programme on this subject. The present study is a part of that programme. In this study, all the hair samples were analyzed by the Proton-induced X-ray Emission (PIXE) method. In all, 102 samples from an adult population in Bangladesh were analyzed. The results on the contents of 12 elements that were possible to be detected with the PIXE method are reported here.
Experimental Each hair sample (- 5 g) was collected from different areas of head with a clean stainless steel clipping scissors. According to the prescribed procedure,‘3’ the samples were washed twice with acetone, three times with double distilled water and finally once with acetone. The washed samples were air dried for 24 h in a clean room A known quantity of each dry sample was charred at 180°C for 1 h in a Pyrex beaker, in order to easily powder the material. The charred sample after cooling and weighing was ground to powder with an aluminium carbide mortar and pestle. Before this operation, a sample of chromatographic grade cellulose powder (Whatman) was ground in the mortar for blank correction, if any. From the powdered material of hair, 50-mg pellets, 7 mm dia. and 1 mm thick, were prepared with a graduated stainless steel hand-press pellet maker (Perkin-Elmer). The pellets were mounted in 35 mm slide frames with adhesive tape and preserved in a desiccator until irradiation. In this investigation, the external beam PIXE method was used to determine trace element contents in hair. The details of the method have been described elsewhere.‘5-7) A schematic diagram of the experimental setup is given in Fig. 1. Kapton foils of 1.12 mg cm-* thickness instead of Be were used as the proton exit windows. Proton beams of nominal
527 *.n.,.3119
-A
M. Husain et al.
528
Scattered
beam 35 mm
Beom --+
NOT
TO
SCALE
FIG. 1. A schematic diagram of the PIXE experimental setup.
of 2.5 MeV from the 3 MeV Van de Graaff accelerator at the Atomic Energy Centre, Dacca (AECD) were used for the irradiation of the targets. After energy loss in the exit window and the air path, the beam energy on the target was about 2 MeV. The targets were placed at 45°C with respect to the beam direction. The beam spot at the exit window was 4 mm. This gave an irradiation spot on the target well within the pellet diameter. The irradiation current was about 30nA. Under these beam conditions, a reasonable counting rate was achieved. The integrated current for each irradiation was 20 pC. Characteristic X-rays were detected with a 30 mm’ Si(Li) detector (Ortec). A 44 mg cm-* plastic absorber energy
was used to reduce the argon background in air. The pulses after amplification were analyzed with a 4096 channel Canberra Analyzer. The data reduction was done manually. Corrections for the overlapping peaks were made from the K,/K, ratios measured separately under identical conditions using cellulose targets doped with the element concerned. A typical X-ray spectrum of a hair sample is illustrated in Fig. 2.
Results and Discussion Concentration calibration and the sensitivity of the method
For trace element concentrations in hair, the PIXE method was calibrated with the NBS orchard leaves
I04 HUMAN = 2
EP Q I03
HEAD
HAIR
MeV
= 20uC
-
I
L 0
1
I
I
5
IO
15
X -
RAY
ENERGY
(k eV)
FIG. 2. An X-ray spectrum from a hair sample irradiated in air as l-mm-thick pellet using a 44 mg cm- * plastic absorber.
529
Trace element concentration in hair
E, = 2.0 ABSORBER
MeV - 44 mg/ cm2
DET. GEOM. =0’018
IS
20
25
30
35
PLASTIC
Sr
40
45
ATOMIC NUMBER FIG. 3. The concentration
calibration curve obtained from the NBS orchard leaves standard for a 40 pC irradiation.
(SRM 1571) standard. The calibration curve shown in Fig. 3, is the X-ray yield per ppm per microcoulomb vs the atomic number of the element. As the NBS recommends to use at least 250 mg of the standard in any experiment, the average peak areas obtained from the irradiation of several 50 mg pellets were used to construct this yield curve. The concentration of the element i in the sample was then simply obtained from Pm
KTW = - QXi 9 at constant geometry
where Y, is the X-ray yield of the element in the sample, T is the dead time correction factor, Q is the integrated charge (PC), Xi is the calibration factor and W is the dry weight factor of the sample. It has been mentioned before that the samples were charred at 180°C to make it easy to grind them to fine powder. In doing so, it was believed that at this low temperature of charring, there would not be any appreciable loss of trace elements. The average weight loss due to charring was found to be 26 k 4%. However, individual weight loss was used in the calculation of concentrations. The blank correction was found to be negligible. The sample homogeneity was tested by irradiating several pellets from the same ma-
terial and it was found within 4%. The geometry variation due to sample positioning was negligible. The applicability of the calibration curve in Fig. 3 for analyzing trace elements in other biological matrices such as hair has been discussed in detail elsewhere.“) In view of the X-ray yields obtained in a number of light element matrices widely varying in proportions of the major elements (H, C, N, 0, etc.), it was observed that such calibrations are universally valid for all biological matrices. The systematic deviation of the curve for different matrices was estimated to be less than 15%. This can, however, be further reduced, if the concentration of the major elements in a given biological matrix is known. The minimum detection limits (MDL) of different elements in the hair matrix are given in Table 1. The MDL of an element, from the consideration of statistical errors in counting, was defined as the amount which would yield an X-ray intensity at least equal to 3a of the background under the peak taken in an interval equal to the FWHM of the peak. For a 20 PC irradiation, it was about 0.3 ppm in the region of iron. Distribution of trace elements in hair
In all, 102 samples were analyzed. The subjects were randomly chosen from about 500 employees of the AECD. The age range of the population group
M. Husain et al.
530 TABLE
1. Minimum detection limit (MDL) in hair matrix for 20 PC irradiation
Element
Atomic No.
MDL in ppm (pg g- ‘)
K F: Cr
19 20 22 24
9.0 3.28 0.90 0.52
Mn Fe Ni CU Zn
25 26 28 29 30
0.41 0.31 0.34 0.33 0.40
Br Sr Pb
35 38 82
0.44 0.76 0.71
surveyed in this study was 2&55 y, the maximum frequency being at 27 y. With the present method, under the experimental conditions mentioned before, twelve elements were found to have concentrations above the detection limits in hair. A summary of these results is given in Table 2. In the calculation of the mean, the data points which do not form a part of the close distribution in the plot of frequency vs logarithm of concentration were not considered. The values of the ranges shown in Table 2 also refer to the close distribution. The arithmetic and the geometric mean for each element was calculated by considering only the data above the background. The calculation of mean values by including the samples below the background, from the consideration of an assumed Gaussian distribution, could not be done, as the distributions obtained were not well behaved. The mean values shown here are, therefore, artificially high for those elements where a fraction of the samples was found to have concentration below the background level. Similarly, in the calculation of the median, only those data points above the background, which form close distribution in log normal vs frequency plot, were considered. The frequency distribution of the concentration of different elements is shown in Fig. 4. The mean and the median in Fig. 4 correspond to the close log distribution as discussed earlier. The uncertainty shown in the case of arithmetic mean (AM) is the standard deviation and in the case of the geometric mean (GM), it is the antilog of standard deviation of the log of concentration. The uncertainties in the median are due to counting statistics. A comparison of our results with those reported from other countries@*@ is shown in Table 2. The data mentioned under reference 3 also include those recently published in the IAEA proceeding”’ and here the range means the range of arithmetic means for different groups. From this comparison, it can be observed that the arithmetic mean of the concentrations of the elements, K, Ca, Cr, Mn, Fe and Ni, is in agreement with similar data found in other countries. The K content of hair (48.4 f 30.1 ppm) from
this study is, however, significantly higher than those in India and Japan”’ (e.g. India: 16.8 f 10.5 ppm, Japan: 18.7 f 23 ppm). The concentration of Cu in Bangladeshi population is lower almost by 40% than the lowest value (AM) reported for this element in hair, while that of Zn (141 f 34 ppm), mostly corresponds to the lowest value of different arithmetic means. HAMMERet ~1.‘~’ have observed that the levels of essential trace elements such as Cu and Zn in hair are not related to environmental exposures. The low contents of Cu and Zn from the present study may thus be related to other factors as diets deficient in these two elements. Such an observation has been reported by McBEAN(‘O)for Zn deficient diets. For some trace elements (e.g. Ti, Sr), there are few published data to make any fruitful comparison. However, for normal JapaneseJ2) the Ti content in hair was found to be 11.7 + 7.0 ppm, with the range of 2.2-35 and IYENGERet df8’ compiled values in the range of 0.048-14ppm (AM) for three different groups. Compared to these results, we have found a range of ~1.5-6.1 with the mean of 3.2 + 1.4ppm. CHUANGand EMERY”‘) have reported a median value of < 20 ppm for Sr in head hair of eleven residents in Hong Kong. IYENGER et al. (*) have reported a range of 0.0460.92 for Sr. In this case, our value is 2.55 f 1.14 ppm with the range of 0.85-5.3 ppm. On the content of Pb in hair, reported results(*) have the range of 3-70 ppm (range of AM) for thirteen different groups. One Canadian study (quoted in @)) has reported values of Pb for rural population, in the range of 0.5-25 ppm with a median of 9.1 ppm while for the urban population, it was 0.5-35 ppm, the median being 15.3 ppm. These are rather high values compared to the results reported here (mean: 4.18 f 2.37 ppm, range: <0.91-11.2 ppm). HAMMERet ~1.‘~’observed that the variation in environmental exposure to human non-essential elements ‘such as Pb, Cd, etc. is reflected in hair. In this regard, the low contents of Pb and Br in head hair from the present study indicate that the population in the Dacca city is less exposed to environmental Pb and also Br, mostly from automobile exhaust and this bears the fact that the traffic concentration in the Dacca city is far less than what is seen in western cities. The peak for Pb L, line (10.55 keV) coincides with the As K, line. But in the absence of As K, line at 11.72 keV and from the consideration of the L,/L, ratio for Pb, the peak at 10.55 keV was considered to be purely due to Pb L, indicating the absence of As in the hair samples analyzed here. It may be noted that the detection limit for As in hair under the conditions of the present study is about 0.4 ppm. Conclusions The concentration of twelve elements (K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Sr and Pb) in the hair of an adult group of 102 individuals in Bangladesh is
102 30 102 102
100 49 96
K Ca Ti Cr Mn
Fe Ni cu Zn
Br Sr Pb
98 40 85
101 28 101 101
14 100 17 36 82
No. of samples in the close distribution
< 0.69-5.44 <0.85-5.32 <0.91-l 1.2
6.25-106.8 40.37-3.25 3.7-13.9 75.6277
< 10.3-149.9 217.7-1423 < 1.5-6.1
Range f + f + +
30.1 255 1.43 1.43 1.35
2.15 _+0.83 2.55 f 1.14 4.18 f 2.37
29.7 17.3 1.25 _+ f 0.72 6.78 _+ 1.60 141 + 34
48.4 652 3.20 2.45 2.33
AM*
1.70 1.75 1.25 1.25
1.88 1.48 1.55 1.85 1.81
2.0 x 1.48 2.30 x 1.58 3.56 $ 1.78
25.76 1.07 xx 6.60 x 137 4
5 x ; x &
GMt 40.1 605 2.91 2.1 1.96
This work
12.3 36.5 0.52 0.32 0.23
2.06 f 0.37 2.24 f 0.60 3.53 _+0.56
25.5 1.16 _+ f 0.34 0.23 6.79 _+0.32 134.4 f 1.10
41.0 f 609 f 2.57 f 2.04 f 1.90 +
Median1
AM
2.3-39 -
60-122s 1.01-18 1l-25.4 138-308
16.8-95 51B2650 -0.46-4.1 1.1-23
(raw4
Ref. 3
element concentration (pg g-i) in hair of normal population
AM Arithmetic mean. GM Geometric mean. * Uncertainties are the SD. t Uncertainties are the antilog of the standard deviation of the log of concentrations. $ Uncertainties are due to counting statistics. 8 For some of the studies, AM’s are not available.
77 102 17 40 92
Element
No. of
samples with detectable cont.
TABLE 2. Trace
GM
1.92-27 -
27-106 2.8-14 9.6-20.6 128-261
14.2-42 3863000 2.4-3.6 0.342.6 0.49-8.8
(range)
0.65-53.3 0.046-0.92 3-70
5-44.7 066.5 11-34 99450
146-3190 0.048-14 0.13-3.65 0.25-5.7
Range
Ref. 8
-
19 218
-
-
Weighted mean
gT
$ 2 z ;; ct. $ E
? 5 % 3 9
MEAN MEDIAN
CO
1. 255 36 5
PPM
652 609,
6
40
IO
2
e.Oloo
I
200
4
41(
6
20
r
I
4
_+ 0
217
PPM
distribution
2
25 5
MEDIAN
0406
297
MEAN
Fe
FIG. 4. Frequency
BK
IO
40 60 100 200
10
20
I
4
6
060
2 24:
10
4
6
20
in hair of a normal
IPPM)
,I4
PPM
2
2 55t
2
061
MEAN MEDIAN
Sr
02
72
6810
0 23
1 16,
PPM
4
MEDlAN
2
I 25 t.0
I
MEAN
NL
0406
I43
2 572052
3 20,
PPM
I
I
MEAN MEDIAN
Pb
2
_I
r
06
population.
IO
20
MEAN MEDIAN
C,
4
6
PPM
IO
4
20
6 610
4
6
10
4 I.92 2 37 3 532 0 56
2
2 45r I43 2 04fO 32
PPM
40
20
------I MEAN MEDIAN
TL
of trace elements
CONCENTRATION
6
34
3
JTlh_
040’6
0 I,
IO
20
41 Oi
MEDlAN
20
4+ 30 I
12 3
PPM
48
K
MEAN
40
20
Trace element concentration in hair
of trace elements, the application of the external beam PIXE method is found to be very convenient to obtain results within 15% accuracy. The mean (AM) concentrations of many of the elements analyzed in this study are found to be comparable to those reported in other countries. However, those of Cu, Zn, Br and Pb are signilkantly lower in Bangladesh than those in other countries and this may be related to dietary habits and other environmental factors such as small local sources of pollureported.
References
In such measurements
Acknowledgements-The authors wish to thank Dr A. A. Katsanos for his fruitful suggestions during the course of this work. The cooperation from Dr M. B. Zaman is recorded with gratitude. The technical assistance rendered by the staff members of the Technical Physics, Chemistry, Experimental Physics, Health Physics and the General Services Divisions of the AECD is gratefully acknowledged. Thanks are due to Mr A. H. M. Habibul Islam, Director, Atomic Energy Centre, Dacca, for his continued support for this research. The secretarial assistance from Mr A. F. Bhuyian is greatly appreciated.
533
Proc. Int. Symp. on Nuclear Life Sciences. IAEA, Vienna Proc. Int. Symp. on Nuclear L$e Sciences, IAEA, Vienna
Activation Analysis in the
(1972). Activation Analysis in the
(1978).
Report IAEA/RI/50 (1978). VALKOMCV. Trace Elements in Human Hair. Garland, New York (1977). KHANA. H., KHALIQUZZAMAN M., HUSAINM., AFJDULLAHM. and KATSANOS A. A. Nucl. Instrum. Meth. 165, 253 (1979).
KATSAN~SA. A., XENOULISA., HADJIANTONIOU A. and FINK R. W. Nucl. Instrum. Meth. 137, 119 (1976). KHALIQUZZAMAN M., ZAMANM. B. and KHAN A. H. (to be published). IYENC~ER G. V., KOLLMENW. E. and BOWENH. J. M. The Elemental Composition ofHuman Tissues and Body Fluids. Verlag Chemie, Weinheim, New York (1978). 9. HAMMERD. I., FINKLEAJ. F., HENDRICKSR. H. and SHY C. M. Am. J. Epidemiol. 93, 84 (1971). Ifi MCBEANL. D., MAHMIJGJI M., REINHOLDJ. G. and 1~. HALSTEDJ. A. Am. J. Clin. Nutrition 24, 505 (1971). 11. CHIJANG L. S. and EMERGYJ. F. J. radioanalyt. Chem. 45, 169 (1978).