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Trace metals in scalp hair of Greek agricultural workers
The Science of the Total Environment, 95 (1990) 149-156 Elsevier
149
TRACE METALS IN SCALP HAIR OF GREEK AGRICULTURAL WORKERS
MICHALIS LEOTSINIDIS and XENOPHON KONDAKIS University of Patras, Laboratory of Public Health, P.O. Box 1045, 261 10 Patras (Greece)
(Received July llth, 1989; accepted October 3rd, 1989)
ABSTRACT
In order to determine "base-line" values of hair metal concentrations in unpolluted, non-industrial areas of Greece, a random sample of 144 agricultural workers (75 males and 69 females) was selected from the Civil Registry of communities of southwest Greece. All subjects were at least 50 years old and had lived in the same community for at least 10 years prior to the investigation. Bulk hair samples were collected and washed with non-ionic detergent and ultrasonic cleaning. Concentrations of six metals (Cd, Pb, Cr, Ni, Zn and Cu) were determined by flameless AAS after wet-digestion. Arithmetic means of concentrations of Cd, Pb, Cr, Ni, Zn and Cu were 0.31, 4.40, 0.85, 0.73, 182.50and 10.48pg g- 1, respectively, for males, and 0.19, 3.84, 1.19, 0.73, 187.60and 10.61/~gg- 1 respectively, for females. Statistically significant (p < 0.05) sex differences were observed for cadmium and nickel. High positive correlations were observed between lead, chromium and copper. High negative correlations were observed between cadmium and zinc. Factor analysis showed that lead, chromium and copper were associated with the first factor. The results are discussed and compared with those observed in other parts of the world. INTRODUCTION T r a c e m e t a l s in h a i r h a v e b o t h e n d o g e n o u s and e x o g e n o u s origins [1, 2]. E n d o g e n o u s q u a n t i t i e s are t h o s e a t t a c h e d to the k e r a t i n molecules d u r i n g the s h o r t period of h a i r f o r m a t i o n ; e x o g e n o u s q u a n t i t i e s are t h o s e a t t a c h e d to the h a i r after it has formed, by direct e n v i r o n m e n t a l c o n t a c t , d e p o s i t i o n or adsorption. T h e o r e t i c a l l y , e n d o g e n o u s c o n c e n t r a t i o n s of elements s h o u l d c o r r e l a t e w i t h the c o n c e n t r a t i o n of t h e c i r c u l a t i n g metals (and, perhaps, body stores) d u r i n g h a i r f o r m a t i o n [3]; e x o g e n o u s c o n c e n t r a t i o n s s h o u l d c o r r e l a t e with e x p o s u r e to suspended m e t a l particles in air (or in dyes, cosmetics, etc.) [4-7]. E v i d e n t l y b o t h origins are e n v i r o n m e n t a l a n d t h e r e f o r e h a i r m e t a l s provide i n d i c a t o r s of t o t a l e n v i r o n m e n t a l exposure. I n Greece, "base-line" d a t a for m e t a l s in h a i r do n o t exist, a l t h o u g h s u c h d a t a are o b v i o u s l y n e c e s s a r y for p u r p o s e s of c o m p a r i s o n w h e n p o l l u t i o n is suspected. T h e aim o f the p r e s e n t s t u d y was to collect "base-line" d a t a for six t r a c e metals (Cd, Pb, Cr, Ni, Zn a n d Cu) by s t u d y i n g t h e i r c o n c e n t r a t i o n s in scalp h a i r o f a g r i c u l t u r a l w o r k e r s in a n a r e a with no industry, no air p o l l u t i o n (except soil dust) a n d m i n i m a l pesticide exposure. I n this area, the use of h a i r
0048-9697/90/$03.50
© 1990 Elsevier Science Publishers B.V.
150 dyes o r o t h e r cosmetics is v e r y r a r e and food c o n s u m p t i o n is similar to t h a t in o t h e r parts of Greece. METHODS
T h e s t u d y was p e r f o r m e d in six c o m m u n i t i e s of n o r t h w e s t Peloponnesos, Greece. T h e p o p u l a t i o n of the c o m m u n i t i e s v a r i e d from 500 to 3100 i n h a b i t a n t s ( N a t i o n a l Census, 1981). Subjects 50 y e a r s old, o r older, were r a n d o m l y selected from the Civil Registry of e a c h c o m m u n i t y and e n r o l l e d in the s t u d y if t h e y fulfilled two conditions: (i) t h e y were a g r i c u l t u r a l w o r k e r s with no i n d u s t r i a l o c c u p a t i o n d u r i n g the last 10 years, (ii) t h e y h a d not resided in a n u r b a n a r e a for m o r e t h a n 6 m o n t h s d u r i n g the last 10 years. Subjects e n r o l l e d were asked to visit a specified h a i r d r e s s e r (one for m e n and a n o t h e r for women) who was given i n s t r u c t i o n s o n how to collect b u l k h a i r from the occipital a r e a of the scalp; t h e y w e r e provided w i t h plastic c o n t a i n e r s for c o l l e c t i o n of 2-4 g o f hair. Six w o m e n did not p r e s e n t t h e m s e l v e s to the h a i r d r e s s e r and finally 75 male samples and 69 female samples were collected (total: 144). M e a n age of males was 65.5 y e a r s and t h a t o f females 63.7 years. After t h o r o u g h u l t r a s o n i c w a s h i n g with 10% SDS solution (150ml) and f u r t h e r w a s h i n g w i t h d e m i n e r a l i z e d w a t e r ( ~ 11), the h a i r sample was dried at 70°C o v e r n i g h t and a sample of 0.5 g was wet-digested ( 1 0 m l N H N O 3 + 2ml HC104) u n t i l a c l e a r s o l u t i o n was obtained. T h e w a s h i n g and wet-digestion p r o c e d u r e s are c o m p a r a b l e to those used by o t h e r w o r k e r s [8-11]. T h e m e t a l d e t e r m i n a t i o n s were p e r f o r m e d by flameless AAS w i t h an a u t o m a t i c sampler ( P e r k i n E l m e r Model 2380 with g r a p h i t e f u r n a c e type HGA-400). S t a n d a r d c u r v e s were c a l c u l a t e d using s t a n d a r d solutions subjected to the same digestion p r o c e d u r e . T w e n t y d u p l i c a t e samples were c h e c k e d by closed wetdigestion p e r f o r m e d in the P e r k i n E l m e r A u t o c l a v e and in no case did the v a r i a b i l i t y exceed 5%. T h e NBS s t a n d a r d B o v i n e L i v e r was used as r e f e r e n c e TABLE 1 Results of hair analyses (males, 75; females, 69) Parameter
Mean
Median Geometric mean SD Min. Max. Lower quartile Upper quartile
Element ~ g g- i) Cadmium
Lead
M
F
M
0.31 0.30 0.25 0.17
0.19 0.19 0.17 0.09
4.40 4.26 3.90 1.97
0.03 0.03 0.86 0.83 0.50 8.93 0.18 0.13 2.86
F
3.84 3.78 3.27 2.08
Nickel
Chromium
Zinc
M
F
M
F
M
0.85 0.82 0.75 0.50
1.19 1.16 1.06 0.56
0.73 0.61 0.50 0.72
0.73 0.56 0.47 1.07
182.50 187.60 10.48 10.61 179.51 184.66 10.52 10.70 179.19 183.26 10.19 10.42 36.19 41.23 2.46 1.83
0.02 8.00
119.88 105.17 301.12 311.03
0.33 0.70
160.81 167.57 8.88 9.94 194.78 206.43 12.12 11.50
0.78 0.24 0.30 0.01 10.69 2.95 3.11 5.00 2.25 0.58 0.84 0.44
0.40 0.24 5.78 4.81 0.96 1.43 0.84
Copper F
M
5.15 16.19
F
4.02 14.75
151
material. For all metals tested our methods yielded results in agreement with the reference values (within 98-102%). Replicate measurements were performed on 20 hair samples; precision was evaluated at between 2 and 6%. Recovery of known amounts of metals added to the hair sample after homogenization and before wet digestion varied from 96 to 102%. All statistical tests used were non-parametric (Mann-Whitney for comparison of two samples and Spearman rank correlation coefficients). Factor analysis was performed by conventional methods on the Spearman correlations matrix with extraction of three factors and varimax orthogonal rotation [12]. RESULTS
Table 1 shows the results separately for each sex. Normal distribution goodness-of-fit tests (~) show that, for males, nickel, chromium and zinc distributions do not fit a normal distribution at the 0.05 level. For females, all distributions, except chromium, fit the normal distribution at the same probability level. Comparison of the two sexes by Mann-Whitney test [13] (Table 2) shows that only cadmium and nickel concentrations are different in the two sexes (0.05 level), the former being higher in males and the latter higher in females. TABLE 2 C o m p a r i s o n of m e a n s b e t w e e n males and females ~ Element
Z value
p
Cadmium Lead Nickel Chromium Zinc Copper
4.43 1.90 - 4.66 1.17 - 0.98 0.72
< 0.001 0.059 < 0.001 > 0.05 0.33 0.47
a M a n n - W h i t n e y test.
TABLE 3 C o r r e l a t i o n m a t r i x (males) Cadmium Cadmium Lead Nickel Chromium Zinc Copper
-
-
-
-
1.00000 0.O945O 0.23603 0.01180 0.56898 0.04543
Lead
Nickel
Chromium
Zinc
Copper
1.00000 - 0.13068 0.57084 - 0.05737 0.58100
1.00000 - 0.07969 0.18114 - 0.25377
1.00000 0.10226 0.51161
1.00000 0.09787
1.00000
Critical value (two-tail, 0.05) = _+0.22701.
152 TABLE 4 C o r r e l a t i o n m a t r i x (females)
Cadmium Lead Nickel Chromium Zinc Copper
Cadmium
Lead
Nickel
Chromium
Zi nc
Copper
1.00000 0.05931 - 0.13056 - 0.19608 - 0.35909 0.15123
1.00000 0.26524 0.31900 0.10919 0.44272
1.00000 0.19632 0.24364 0.17235
1.00000 0.21173 0.28119
1.00000 0.03613
1.00000
C r i t i c a l v a l u e (two-tail, 0.05) = + 0.23673.
Correlation coefficients (Spearman's rank) between the metals are shown in Tables 3 and 4 for males and females, respectively. There are high positive correlations between chromium, lead and copper. Most of the nickel correlations are negative or not significant. Cadmium shows no significant correlation, but there is a significant correlation with zinc, which also does n o t correlate with other metals. Conventional factor analysis was performed on the two correlation matrices with extraction of three factors (Tables 5 and 6 for males and females, respectively) and varimax rotation. Cadmium provides the highest eigenvalue and nickel the lowest. TABLE 5 F a c t o r a n a l y s i s a n d r o t a t e d f a c t o r s (males) Factors matrix Variable/factor 1 Cadmium Lead Nickel Chromium Zinc Copper
0.06182 0.74346 - 0.23805 0.67483 0.01518 0.72427
Eigenvalue 2 - 0.68160 - 0.04888 0.29030 0.11001 0.67759 0.08707
3 -
0.03721 0.09944 0.23704 0.09828 0.05778 0.11770
Varimax rotated factor matrix Variable/factor 1
Cadmium Lead Nickel Chromium Zinc Copper
0.00632 0.74017 - 0.15545 0.68750 0.06393 0.68802
2 - 0.67343 -0.10033 0.23637 0.05707 0.67125 0.08311
3 0.12741 0.08425 -0.34219 0.03516 - 0.08961 0.25638
1.59342 1.03005 0.09431 - 0.13609 - 0.22242 - 0.24008
153 TABLE 6 Factor analysis and rotated factors (females) Factor matrix Variable/factor i
Cadmium Lead Nickel Chromium Zinc Copper
-
18057 0.57351 0.42681 0.52160 0.49064 0.49064
Eigenvalue 2 0.53017 0.25290 - 0.10173 - 0.06531 0.35355 0.35355
3 - 0.02736 - 0.01062 - 0.08350 0.07320 0.01313 0.01313
-
1.18522 0.64865 0.01384 0.15257 0.24409 0.24409
Varimax rotated factor matrix Variable/factor 1 Cadmium Lead Nickel Chromium Zinc Copper
0.08199 0.62500 0.32981 0.43551 0.13221 0.59830
2 - 0.55406 0.03833 0.28574 0.29771 0.52431 - 0.08899
3 - 0.02691 0.03001 0.09520 - 0.05827 0.00474 0.00474
The rotated factor loadings show almost similar patterns. Lead, chromium a n d c o p p e r a r e a s s o c i a t e d w i t h t h e f i r s t f a c t o r , w h i l e t h e s e c o n d f a c t o r is c h a r a c t e r i z e d b y t h e o p p o s i t i o n b e t w e e n c a d m i u m a n d zinc. L o a d i n g s w i t h t h e t h i r d f a c t o r a r e g e n e r a l l y v e r y low. DISCUSSION T h i s s t u d y w a s r e s t r i c t e d t o p e o p l e t> 50 y e a r s o f a g e b e c a u s e p e o p l e o f t h a t a g e v i s i t t h e n e i g h b o u r i n g t o w n ( P a t r a s , 160 000 i n h a b i t a n t s ) l e s s f r e q u e n t l y than younger people and therefore they were less likely to be exposed to traffic or industrial pollutants. C o m p a r i s o n o f o u r r e s u l t s w i t h t h o s e o f o t h e r i n v e s t i g a t i o n s [4, 14-17] ( T a b l e 7) o f r u r a l p o p u l a t i o n s s h o w s t h a t o u r v a l u e s a r e o f t h e s a m e o r d e r o f magnitude as most other studies. However, differences do exist, for example in t h e f e m a l e s a m p l e o f H u s a i n e t al. [14], w h e r e t h e c o n c e n t r a t i o n s a r e m u c h lower than our values or those of other studies. In general, our results are very s i m i l a r t o t h o s e o f M o o n e t al. [15], b u t t h e s e d a t a w e r e o b t a i n e d f o r a m u c h younger population. It should be noted that, in this study, the Ni concentration appears to be generally higher than in other studies, for an unknown reason. Correlations between trace metal concentrations proved to be quite interesti n g . C r e a s o n e t al. [18] h a s p u b l i s h e d a c o r r e l a t i o n m a t r i x i n o r d e r t o s h o w
154
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155 positive or negative correlations without any further analysis. In the present w o r k , i t is f o u n d t h a t l e a d , c h r o m i u m a n d c o p p e r b e h a v e s i m i l a r l y i n t h e f a c t o r a n a l y s i s , b u t t h e r e a s o n s for t h i s a r e n o t c l e a r . C h r o m i u m a n d c o p p e r a r e c o n s i d e r e d to b e e s s e n t i a l t r a c e e l e m e n t s , w h i l e l e a d is n o t . A n i n t e r e s t i n g f i n d i n g o f t h e p r e s e n t w o r k is t h e h i g h n e g a t i v e c o r r e l a t i o n c o e f f i c i e n t b e t w e e n c a d m i u m a n d zinc. T h e m e t a b o l i c c o m p e t i t i o n b e t w e e n t h e s e t w o t r a c e e l e m e n t s is w e l l e s t a b l i s h e d [19], a n d t h e r e f o r e i t s m a n i f e s t a t i o n i n h a i r m e t a l c o n c e n t r a t i o n s s h o u l d n o t b e s u r p r i s i n g , a s i t is w e l l k n o w n t h a t b o d y m e t a b o l i c p r o c e s s e s i n f l u e n c e t r a c e m e t a l c o n c e n t r a t i o n s i n h a i r [3, 20, 21]. REFERENCES 1 2 3 4
5 6 7 8
9 10 11 12 13 14 15
16 17
N. Limic and V. Valkonic, Environmental influence on trace element levels in human hair, Bull. Environ. Contam. Toxicol., 37 (1986) 925-930. M. Laker, On determining trace element levels in man: the use of blood and hair, Lancet, 8292, Vol. 2 (1982) 260-262 H.C. Hopps, The biological basis for using hair and nail for analyses of trace elements, Sci. Total Environ., 7 (1977) 71-89. A. Chart, A.C. Secord, B. Tiefenbach and E.R. Jervis, Scalp hair as a monitor of community exposure to environmental pollutants, in A.C. Brown and R.G. Crounse (Eds), Hair Trace Elements and Human Illness, Praeger Press, New York, 1980, pp. 46-73. K.R. Bhat, J. Arunachalam, S. Yegnasubramanian and S. Gangadharan, Trace elements in hair and environmental exposure, Sci. Total Environ., 22 (1982) 169-178. A. Chattopadhyay, T.M. Robbers and R.E. Jarvis, Scalp hair as a monitor for community exposure to lead, Arch. Environ. Health, 30 (1977) 226-236. P. Chanet, S.M. De Antonio, S.A. Korz and D.M. Scheiner, Effects of some cosmetics on copper and zinc, Clin. Chem., 28 (1982) 2450. O. Guillard, J.C. Brugier, A. Piriou, M. Menard, J. Combert and D. Reiss, Improved determination of manganese in hair by use of a mini-autoclave and flameless atomic absorption spectrometry with Zeeman background correction; an evaluation of unexposed subjects, Clin. Chem., 30 (1985) 1642-1645. G.C.Assarlan and D. Oberleas, Effect of washing procedures on trace-element content of hair, Clin. Chem., 23]9 (1977) 1771-1777. K. Okamoto, M. Morita, H. Quan, T. Vehiro and K. Fuwa, Preparation and certification of human hair powder reference material, Clin. Chem., 31 (1985) 1592-1597. D.E. Ryan, J. Holzbecher and D.C. Stuart, Trace elements in scalp hair of persons with multiple sclerosis and of normal individuals, Clin. Chem., 24 (1978) 1996-2000. W.R.Dillon and M. Goldstein, Multivariate Analysis Methods and Applications, John Wiley and Sons, Inc., New York, 1984, pp. 53-59. P. Armitage, Statistical Methods in Medical Research, Blackwell Scientific, London, 1980, pp. 398-401. M. Husain, M. Khaliguzzaman, M. Abdullah, I. Ahmed and A. Khan, Trace element concentration in hair of the Bangladeshi population, Int. J. Apph Radiat. Isot., 31 (1980) 527-533. J. Moon, T.J. Smith, S. Tamaro, D. Enarson, S. Fadl, A.J. Davison and 1. Weldon, Trace metals in scalp hair of children and adults in three Alberta Indian villages, Sci. Total Environ., 54 (1986) 107-125. I. Othman and N.M. Spyrou, The abundance of some elements in hair and nail from the Machakos district of Kenya, Sci. Total Environ., 16 (1980) 267-278. N. Baumslag and H. Petering, Trace metals studies in busman hair, Arch. Environ. Health, 29 (1976) 255-257.
156 18 19 20
21
J.P. Creason, T.A. Hinnes, J.E. Bumgarner and C. Pinkerton, Trace elements in hair as related to exposure in metropolitan New York, Clin. Chem., 21 (1975) 60~612. H.H. Sandstead, Interactions of cadmium and lead with essential minerals, in G.F. Nordberg (Ed.), Effects and Dose-Response Relationship of Toxic Metals, Elsevier, Amsterdam, 1976. A.J.J. Bos, C.C.A.H. van der Stap, V. Valkovid, R.D. Vis and H. Verheul, Incorporation routes of elements into human hair; implications for hair analysis used for monitoring, Sci. Total Environ., 42 (1985) 157-169. T.H. Maugh, Hair: a diagnostic tool to complement blood, serum and urine, Science, 202 (1978) 1271-1273.
149
TRACE METALS IN SCALP HAIR OF GREEK AGRICULTURAL WORKERS
MICHALIS LEOTSINIDIS and XENOPHON KONDAKIS University of Patras, Laboratory of Public Health, P.O. Box 1045, 261 10 Patras (Greece)
(Received July llth, 1989; accepted October 3rd, 1989)
ABSTRACT
In order to determine "base-line" values of hair metal concentrations in unpolluted, non-industrial areas of Greece, a random sample of 144 agricultural workers (75 males and 69 females) was selected from the Civil Registry of communities of southwest Greece. All subjects were at least 50 years old and had lived in the same community for at least 10 years prior to the investigation. Bulk hair samples were collected and washed with non-ionic detergent and ultrasonic cleaning. Concentrations of six metals (Cd, Pb, Cr, Ni, Zn and Cu) were determined by flameless AAS after wet-digestion. Arithmetic means of concentrations of Cd, Pb, Cr, Ni, Zn and Cu were 0.31, 4.40, 0.85, 0.73, 182.50and 10.48pg g- 1, respectively, for males, and 0.19, 3.84, 1.19, 0.73, 187.60and 10.61/~gg- 1 respectively, for females. Statistically significant (p < 0.05) sex differences were observed for cadmium and nickel. High positive correlations were observed between lead, chromium and copper. High negative correlations were observed between cadmium and zinc. Factor analysis showed that lead, chromium and copper were associated with the first factor. The results are discussed and compared with those observed in other parts of the world. INTRODUCTION T r a c e m e t a l s in h a i r h a v e b o t h e n d o g e n o u s and e x o g e n o u s origins [1, 2]. E n d o g e n o u s q u a n t i t i e s are t h o s e a t t a c h e d to the k e r a t i n molecules d u r i n g the s h o r t period of h a i r f o r m a t i o n ; e x o g e n o u s q u a n t i t i e s are t h o s e a t t a c h e d to the h a i r after it has formed, by direct e n v i r o n m e n t a l c o n t a c t , d e p o s i t i o n or adsorption. T h e o r e t i c a l l y , e n d o g e n o u s c o n c e n t r a t i o n s of elements s h o u l d c o r r e l a t e w i t h the c o n c e n t r a t i o n of t h e c i r c u l a t i n g metals (and, perhaps, body stores) d u r i n g h a i r f o r m a t i o n [3]; e x o g e n o u s c o n c e n t r a t i o n s s h o u l d c o r r e l a t e with e x p o s u r e to suspended m e t a l particles in air (or in dyes, cosmetics, etc.) [4-7]. E v i d e n t l y b o t h origins are e n v i r o n m e n t a l a n d t h e r e f o r e h a i r m e t a l s provide i n d i c a t o r s of t o t a l e n v i r o n m e n t a l exposure. I n Greece, "base-line" d a t a for m e t a l s in h a i r do n o t exist, a l t h o u g h s u c h d a t a are o b v i o u s l y n e c e s s a r y for p u r p o s e s of c o m p a r i s o n w h e n p o l l u t i o n is suspected. T h e aim o f the p r e s e n t s t u d y was to collect "base-line" d a t a for six t r a c e metals (Cd, Pb, Cr, Ni, Zn a n d Cu) by s t u d y i n g t h e i r c o n c e n t r a t i o n s in scalp h a i r o f a g r i c u l t u r a l w o r k e r s in a n a r e a with no industry, no air p o l l u t i o n (except soil dust) a n d m i n i m a l pesticide exposure. I n this area, the use of h a i r
0048-9697/90/$03.50
© 1990 Elsevier Science Publishers B.V.
150 dyes o r o t h e r cosmetics is v e r y r a r e and food c o n s u m p t i o n is similar to t h a t in o t h e r parts of Greece. METHODS
T h e s t u d y was p e r f o r m e d in six c o m m u n i t i e s of n o r t h w e s t Peloponnesos, Greece. T h e p o p u l a t i o n of the c o m m u n i t i e s v a r i e d from 500 to 3100 i n h a b i t a n t s ( N a t i o n a l Census, 1981). Subjects 50 y e a r s old, o r older, were r a n d o m l y selected from the Civil Registry of e a c h c o m m u n i t y and e n r o l l e d in the s t u d y if t h e y fulfilled two conditions: (i) t h e y were a g r i c u l t u r a l w o r k e r s with no i n d u s t r i a l o c c u p a t i o n d u r i n g the last 10 years, (ii) t h e y h a d not resided in a n u r b a n a r e a for m o r e t h a n 6 m o n t h s d u r i n g the last 10 years. Subjects e n r o l l e d were asked to visit a specified h a i r d r e s s e r (one for m e n and a n o t h e r for women) who was given i n s t r u c t i o n s o n how to collect b u l k h a i r from the occipital a r e a of the scalp; t h e y w e r e provided w i t h plastic c o n t a i n e r s for c o l l e c t i o n of 2-4 g o f hair. Six w o m e n did not p r e s e n t t h e m s e l v e s to the h a i r d r e s s e r and finally 75 male samples and 69 female samples were collected (total: 144). M e a n age of males was 65.5 y e a r s and t h a t o f females 63.7 years. After t h o r o u g h u l t r a s o n i c w a s h i n g with 10% SDS solution (150ml) and f u r t h e r w a s h i n g w i t h d e m i n e r a l i z e d w a t e r ( ~ 11), the h a i r sample was dried at 70°C o v e r n i g h t and a sample of 0.5 g was wet-digested ( 1 0 m l N H N O 3 + 2ml HC104) u n t i l a c l e a r s o l u t i o n was obtained. T h e w a s h i n g and wet-digestion p r o c e d u r e s are c o m p a r a b l e to those used by o t h e r w o r k e r s [8-11]. T h e m e t a l d e t e r m i n a t i o n s were p e r f o r m e d by flameless AAS w i t h an a u t o m a t i c sampler ( P e r k i n E l m e r Model 2380 with g r a p h i t e f u r n a c e type HGA-400). S t a n d a r d c u r v e s were c a l c u l a t e d using s t a n d a r d solutions subjected to the same digestion p r o c e d u r e . T w e n t y d u p l i c a t e samples were c h e c k e d by closed wetdigestion p e r f o r m e d in the P e r k i n E l m e r A u t o c l a v e and in no case did the v a r i a b i l i t y exceed 5%. T h e NBS s t a n d a r d B o v i n e L i v e r was used as r e f e r e n c e TABLE 1 Results of hair analyses (males, 75; females, 69) Parameter
Mean
Median Geometric mean SD Min. Max. Lower quartile Upper quartile
Element ~ g g- i) Cadmium
Lead
M
F
M
0.31 0.30 0.25 0.17
0.19 0.19 0.17 0.09
4.40 4.26 3.90 1.97
0.03 0.03 0.86 0.83 0.50 8.93 0.18 0.13 2.86
F
3.84 3.78 3.27 2.08
Nickel
Chromium
Zinc
M
F
M
F
M
0.85 0.82 0.75 0.50
1.19 1.16 1.06 0.56
0.73 0.61 0.50 0.72
0.73 0.56 0.47 1.07
182.50 187.60 10.48 10.61 179.51 184.66 10.52 10.70 179.19 183.26 10.19 10.42 36.19 41.23 2.46 1.83
0.02 8.00
119.88 105.17 301.12 311.03
0.33 0.70
160.81 167.57 8.88 9.94 194.78 206.43 12.12 11.50
0.78 0.24 0.30 0.01 10.69 2.95 3.11 5.00 2.25 0.58 0.84 0.44
0.40 0.24 5.78 4.81 0.96 1.43 0.84
Copper F
M
5.15 16.19
F
4.02 14.75
151
material. For all metals tested our methods yielded results in agreement with the reference values (within 98-102%). Replicate measurements were performed on 20 hair samples; precision was evaluated at between 2 and 6%. Recovery of known amounts of metals added to the hair sample after homogenization and before wet digestion varied from 96 to 102%. All statistical tests used were non-parametric (Mann-Whitney for comparison of two samples and Spearman rank correlation coefficients). Factor analysis was performed by conventional methods on the Spearman correlations matrix with extraction of three factors and varimax orthogonal rotation [12]. RESULTS
Table 1 shows the results separately for each sex. Normal distribution goodness-of-fit tests (~) show that, for males, nickel, chromium and zinc distributions do not fit a normal distribution at the 0.05 level. For females, all distributions, except chromium, fit the normal distribution at the same probability level. Comparison of the two sexes by Mann-Whitney test [13] (Table 2) shows that only cadmium and nickel concentrations are different in the two sexes (0.05 level), the former being higher in males and the latter higher in females. TABLE 2 C o m p a r i s o n of m e a n s b e t w e e n males and females ~ Element
Z value
p
Cadmium Lead Nickel Chromium Zinc Copper
4.43 1.90 - 4.66 1.17 - 0.98 0.72
< 0.001 0.059 < 0.001 > 0.05 0.33 0.47
a M a n n - W h i t n e y test.
TABLE 3 C o r r e l a t i o n m a t r i x (males) Cadmium Cadmium Lead Nickel Chromium Zinc Copper
-
-
-
-
1.00000 0.O945O 0.23603 0.01180 0.56898 0.04543
Lead
Nickel
Chromium
Zinc
Copper
1.00000 - 0.13068 0.57084 - 0.05737 0.58100
1.00000 - 0.07969 0.18114 - 0.25377
1.00000 0.10226 0.51161
1.00000 0.09787
1.00000
Critical value (two-tail, 0.05) = _+0.22701.
152 TABLE 4 C o r r e l a t i o n m a t r i x (females)
Cadmium Lead Nickel Chromium Zinc Copper
Cadmium
Lead
Nickel
Chromium
Zi nc
Copper
1.00000 0.05931 - 0.13056 - 0.19608 - 0.35909 0.15123
1.00000 0.26524 0.31900 0.10919 0.44272
1.00000 0.19632 0.24364 0.17235
1.00000 0.21173 0.28119
1.00000 0.03613
1.00000
C r i t i c a l v a l u e (two-tail, 0.05) = + 0.23673.
Correlation coefficients (Spearman's rank) between the metals are shown in Tables 3 and 4 for males and females, respectively. There are high positive correlations between chromium, lead and copper. Most of the nickel correlations are negative or not significant. Cadmium shows no significant correlation, but there is a significant correlation with zinc, which also does n o t correlate with other metals. Conventional factor analysis was performed on the two correlation matrices with extraction of three factors (Tables 5 and 6 for males and females, respectively) and varimax rotation. Cadmium provides the highest eigenvalue and nickel the lowest. TABLE 5 F a c t o r a n a l y s i s a n d r o t a t e d f a c t o r s (males) Factors matrix Variable/factor 1 Cadmium Lead Nickel Chromium Zinc Copper
0.06182 0.74346 - 0.23805 0.67483 0.01518 0.72427
Eigenvalue 2 - 0.68160 - 0.04888 0.29030 0.11001 0.67759 0.08707
3 -
0.03721 0.09944 0.23704 0.09828 0.05778 0.11770
Varimax rotated factor matrix Variable/factor 1
Cadmium Lead Nickel Chromium Zinc Copper
0.00632 0.74017 - 0.15545 0.68750 0.06393 0.68802
2 - 0.67343 -0.10033 0.23637 0.05707 0.67125 0.08311
3 0.12741 0.08425 -0.34219 0.03516 - 0.08961 0.25638
1.59342 1.03005 0.09431 - 0.13609 - 0.22242 - 0.24008
153 TABLE 6 Factor analysis and rotated factors (females) Factor matrix Variable/factor i
Cadmium Lead Nickel Chromium Zinc Copper
-
18057 0.57351 0.42681 0.52160 0.49064 0.49064
Eigenvalue 2 0.53017 0.25290 - 0.10173 - 0.06531 0.35355 0.35355
3 - 0.02736 - 0.01062 - 0.08350 0.07320 0.01313 0.01313
-
1.18522 0.64865 0.01384 0.15257 0.24409 0.24409
Varimax rotated factor matrix Variable/factor 1 Cadmium Lead Nickel Chromium Zinc Copper
0.08199 0.62500 0.32981 0.43551 0.13221 0.59830
2 - 0.55406 0.03833 0.28574 0.29771 0.52431 - 0.08899
3 - 0.02691 0.03001 0.09520 - 0.05827 0.00474 0.00474
The rotated factor loadings show almost similar patterns. Lead, chromium a n d c o p p e r a r e a s s o c i a t e d w i t h t h e f i r s t f a c t o r , w h i l e t h e s e c o n d f a c t o r is c h a r a c t e r i z e d b y t h e o p p o s i t i o n b e t w e e n c a d m i u m a n d zinc. L o a d i n g s w i t h t h e t h i r d f a c t o r a r e g e n e r a l l y v e r y low. DISCUSSION T h i s s t u d y w a s r e s t r i c t e d t o p e o p l e t> 50 y e a r s o f a g e b e c a u s e p e o p l e o f t h a t a g e v i s i t t h e n e i g h b o u r i n g t o w n ( P a t r a s , 160 000 i n h a b i t a n t s ) l e s s f r e q u e n t l y than younger people and therefore they were less likely to be exposed to traffic or industrial pollutants. C o m p a r i s o n o f o u r r e s u l t s w i t h t h o s e o f o t h e r i n v e s t i g a t i o n s [4, 14-17] ( T a b l e 7) o f r u r a l p o p u l a t i o n s s h o w s t h a t o u r v a l u e s a r e o f t h e s a m e o r d e r o f magnitude as most other studies. However, differences do exist, for example in t h e f e m a l e s a m p l e o f H u s a i n e t al. [14], w h e r e t h e c o n c e n t r a t i o n s a r e m u c h lower than our values or those of other studies. In general, our results are very s i m i l a r t o t h o s e o f M o o n e t al. [15], b u t t h e s e d a t a w e r e o b t a i n e d f o r a m u c h younger population. It should be noted that, in this study, the Ni concentration appears to be generally higher than in other studies, for an unknown reason. Correlations between trace metal concentrations proved to be quite interesti n g . C r e a s o n e t al. [18] h a s p u b l i s h e d a c o r r e l a t i o n m a t r i x i n o r d e r t o s h o w
154
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155 positive or negative correlations without any further analysis. In the present w o r k , i t is f o u n d t h a t l e a d , c h r o m i u m a n d c o p p e r b e h a v e s i m i l a r l y i n t h e f a c t o r a n a l y s i s , b u t t h e r e a s o n s for t h i s a r e n o t c l e a r . C h r o m i u m a n d c o p p e r a r e c o n s i d e r e d to b e e s s e n t i a l t r a c e e l e m e n t s , w h i l e l e a d is n o t . A n i n t e r e s t i n g f i n d i n g o f t h e p r e s e n t w o r k is t h e h i g h n e g a t i v e c o r r e l a t i o n c o e f f i c i e n t b e t w e e n c a d m i u m a n d zinc. T h e m e t a b o l i c c o m p e t i t i o n b e t w e e n t h e s e t w o t r a c e e l e m e n t s is w e l l e s t a b l i s h e d [19], a n d t h e r e f o r e i t s m a n i f e s t a t i o n i n h a i r m e t a l c o n c e n t r a t i o n s s h o u l d n o t b e s u r p r i s i n g , a s i t is w e l l k n o w n t h a t b o d y m e t a b o l i c p r o c e s s e s i n f l u e n c e t r a c e m e t a l c o n c e n t r a t i o n s i n h a i r [3, 20, 21]. REFERENCES 1 2 3 4
5 6 7 8
9 10 11 12 13 14 15
16 17
N. Limic and V. Valkonic, Environmental influence on trace element levels in human hair, Bull. Environ. Contam. Toxicol., 37 (1986) 925-930. M. Laker, On determining trace element levels in man: the use of blood and hair, Lancet, 8292, Vol. 2 (1982) 260-262 H.C. Hopps, The biological basis for using hair and nail for analyses of trace elements, Sci. Total Environ., 7 (1977) 71-89. A. Chart, A.C. Secord, B. Tiefenbach and E.R. Jervis, Scalp hair as a monitor of community exposure to environmental pollutants, in A.C. Brown and R.G. Crounse (Eds), Hair Trace Elements and Human Illness, Praeger Press, New York, 1980, pp. 46-73. K.R. Bhat, J. Arunachalam, S. Yegnasubramanian and S. Gangadharan, Trace elements in hair and environmental exposure, Sci. Total Environ., 22 (1982) 169-178. A. Chattopadhyay, T.M. Robbers and R.E. Jarvis, Scalp hair as a monitor for community exposure to lead, Arch. Environ. Health, 30 (1977) 226-236. P. Chanet, S.M. De Antonio, S.A. Korz and D.M. Scheiner, Effects of some cosmetics on copper and zinc, Clin. Chem., 28 (1982) 2450. O. Guillard, J.C. Brugier, A. Piriou, M. Menard, J. Combert and D. Reiss, Improved determination of manganese in hair by use of a mini-autoclave and flameless atomic absorption spectrometry with Zeeman background correction; an evaluation of unexposed subjects, Clin. Chem., 30 (1985) 1642-1645. G.C.Assarlan and D. Oberleas, Effect of washing procedures on trace-element content of hair, Clin. Chem., 23]9 (1977) 1771-1777. K. Okamoto, M. Morita, H. Quan, T. Vehiro and K. Fuwa, Preparation and certification of human hair powder reference material, Clin. Chem., 31 (1985) 1592-1597. D.E. Ryan, J. Holzbecher and D.C. Stuart, Trace elements in scalp hair of persons with multiple sclerosis and of normal individuals, Clin. Chem., 24 (1978) 1996-2000. W.R.Dillon and M. Goldstein, Multivariate Analysis Methods and Applications, John Wiley and Sons, Inc., New York, 1984, pp. 53-59. P. Armitage, Statistical Methods in Medical Research, Blackwell Scientific, London, 1980, pp. 398-401. M. Husain, M. Khaliguzzaman, M. Abdullah, I. Ahmed and A. Khan, Trace element concentration in hair of the Bangladeshi population, Int. J. Apph Radiat. Isot., 31 (1980) 527-533. J. Moon, T.J. Smith, S. Tamaro, D. Enarson, S. Fadl, A.J. Davison and 1. Weldon, Trace metals in scalp hair of children and adults in three Alberta Indian villages, Sci. Total Environ., 54 (1986) 107-125. I. Othman and N.M. Spyrou, The abundance of some elements in hair and nail from the Machakos district of Kenya, Sci. Total Environ., 16 (1980) 267-278. N. Baumslag and H. Petering, Trace metals studies in busman hair, Arch. Environ. Health, 29 (1976) 255-257.
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21
J.P. Creason, T.A. Hinnes, J.E. Bumgarner and C. Pinkerton, Trace elements in hair as related to exposure in metropolitan New York, Clin. Chem., 21 (1975) 60~612. H.H. Sandstead, Interactions of cadmium and lead with essential minerals, in G.F. Nordberg (Ed.), Effects and Dose-Response Relationship of Toxic Metals, Elsevier, Amsterdam, 1976. A.J.J. Bos, C.C.A.H. van der Stap, V. Valkovid, R.D. Vis and H. Verheul, Incorporation routes of elements into human hair; implications for hair analysis used for monitoring, Sci. Total Environ., 42 (1985) 157-169. T.H. Maugh, Hair: a diagnostic tool to complement blood, serum and urine, Science, 202 (1978) 1271-1273.