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Zinc and copper levels in serum and urine: relationship to biological, habitual and environmental factors
the Science of the Total Environment ELSEVIER
The Science of the Total Environment 148 (1994) 67-72
Zinc and copper levels in serum and urine: relationship to biological, habitual and environmental factors M. Schuhmacher
a, J . L . D o m i n g o *a'b, J. C o r b e l l a b
ULaboratory of Toxicology and Biochemistry, School of Medicine, Rovira i Virgili University, 43201 Reus, Spain hDepartment of Toxicology, University of Barcelona, 08036 Barcelona, Spain
(Received 15 February 1993; accepted 18 April 1993)
Abstract Zinc and copper levels were determined in serum and urine of 434 subjects living in an industrial and an agricultural area of Tarragona Province, Spain. Zinc and copper concentrations were related to a range of factors such as sex, age, blood pressure, and drinking and smoking habits. Geometric mean serum zinc and copper concentrations were, respectively, 113.9 and 84 ~g dl -I, while the mean values for urine zinc and copper concentrations were 698.7 and 26.6/~g g-J creatinine. Serum zinc and copper levels and urine copper concentrations in men were significantly lower than in women, while there were no differences in serum or urinary zinc and copper levels with age. The consumption of alcohol significantly reduced the levels of zinc and copper in serum, whereas blood pressure had no influence on these values. The levels of zinc and copper in urine were not affected by the smoking and drinking habits, place of residence, or blood pressure. In general terms, the results of this study agree with previously reported values from different countries. Key words: Zinc levels: Copper levels; Serum; Urine; Spanish population
1. Introduction Metals are released into the environment from a wide spectrum o f natural and anthropogenic sources [1]. The greatly increased circulation o f metals through the air, water and soils, and their inevitable transfer to the h u m a n food chain remains an important environmental issue which entails some u n k n o w n health risks for future generations [2]. Some of these metals (lead, cadmium, * Corresponding author.
mercury) are clearly toxic, while other such as zinc, copper, iron, manganese, etc. are essential for animals and h u m a n beings. Nevertheless, the beneficial biological effect o f an element depends on its concentration in the organism. Thus, both the absence and the excess o f essential microelements may produce undesirable effects [3,4]. Zinc is essential for the biological functions o f all living matter, e.g. for growth, testicular maturation, skin integrity, mental activity, w o u n d healing and immunocompetence. Zinc is also required for the metabolic activities o f over 70 metalloenzymes
0048-9697/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved. SSDI 0048-9697(93)03720-M
68
M. Schuhmacher et al. / Sci. Total Environ. 148 (1994) 67-72
[5-7]. In contrast, toxicity of zinc is low; however, some toxic effects in humans have been reported
2. Materials and methods
[5,81.
Two hundred and fifty-one men and 183 women (ages between 16 and 65 years) were the target subjects in this work. Only those who were not occupationally exposed to zinc and copper were included. Extensive descriptions of the study areas were recently reported [12-14]. Blood samples were drawn with special care by venipuncture, using cleaned syringes and stainless steel hypodermic needles, into nitric acid-cleaned glass tubes. Serum samples were then obtained by centrifugation and were kept frozen at -20°C until analysis. The urine was collected as a spot sample in polypropylene bottles treated beforehand with 10% nitric acid. Each urine sample was maintained by freezing at -20°C until analyses were performed. A questionnaire including sex, age, occupation, smoking and drinking habits, medications, as well as previous hepatic or renal diseases was filled up by the participants in the study. Blood pressure was also measured and recorded. Serum and urine samples of 1 ml were predigested with 2 ml of 65% nitric acid (Suprapur grade, Merck, Darmstadt, FRG) at room temperature for 12 h. The predigested samples were then heated at 110°C for 6 h, and subsequently at 150°C until the ashing procedure was completed. After cooling, ashed samples were diluted with 0.1 M nitric acid to 10 ml and kept in polypropylene bottles. All
Copper is also an important factor for several enzyme systems and is involved in the mobilization and release of storage iron from liver, the formation of myelin and bone, the maintenance of elastin in great blood vessels, and like zinc, is important in maintaining blood pressure [9-11]. Although copper toxicity in humans is rather rare, it can be toxic in man, producing nausea, vomiting, diarrhea and malaise [10]. Two frequently used indicators for body zinc and copper status are hair and serum concentrations. In a recent study performed in an industrial and a rural area of Tarragona Province (southern Catalonia, Spain), the concentrations of zinc and copper were determined in 302 hair samples of children living in these areas [12]. The aim of the present study was to establish the reference range of zinc and copper concentrations in serum and urine of people living in Tarragona Province. The northern area of this province is basically industrial, while the southern area is essentially agricultural. According to previous investigations, people living in both areas are exposed to low levels of zinc and copper through the food chain [13]. The effects of sex, age, smoking and drinking habits, and blood pressure on serum and urine zinc and copper levels were also evaluated.
Table 1 Zinc and copper levels in serum and urine of a general population, classified by sex a Sex
P
Men
Zinc Serum (/zg dl -j) Urine (/zg g-l Creat.) Copper Serum (/zg dl -t) Urine (ttg g-I Creat.)
Women
N
GM
GSD
N
GM
GSD
196 241
106.3 782.1
98.7 600.9
175 177
123.1 598.8
102.3 464.2
<0.001 NS
248 251
77.7 18.0
0.1 5.1
183 183
94.3 45.2
0.2 23.4
<0.001 <0.05
aN, number of samples analyzed; GM, geometric mean; GSD, geometric standard deviation; NS, not significant (denotes P > 0.05).
69
M. Schuhmacher et al./ Sci. Total Environ. 148 (1994) 67-72 Table 2 Zinc and copper levels in serum and urine of a general population, classified by age a Age (years)
N Zinc Serum (#g dl -I) Urine (p.g g-I Creat.) Copper Serum (p,g dl -I) Urine (/zg g-I Creat.)
16-25
26-35
36-45
111
152
82
46-55
56-65
54
26
128.8 4. 98.1 719.9 4. 650.5
119.1 4. 86.0 830.6 4. 710.4
98.1 4. 83.7 549.4 4. 322.0
102.8 4. 89.6 704.6 4. 514.7
105.1 ± 79.1 430.0 4- 383.5
79.8 4. 0.1 27.1 q- 10.8
87.1 4. 0.2 16.2 4. 5.0
88.8 4. 0.1 45.2 4. 33.1
77.0 q- 0.1 31.2 4. 6.4
90.3 ± 0.1 58,1 ± 25.9
aResults are presented as geometric means 4. geometric standard deviations. N, number of samples.
glassware and bottles were previously soaked in diluted nitric acid for 24 h and rinsed thoroughly with deionized distilled water. The zinc concentrations were measured by the flame atomic absorption spectrometry method only (Perk±n-Elmer 4000); copper levels were determined by inductively coupled plasma atomic emission spectrometry (Jobin Yvon 38 VHR). Three replicate determinations were made for each solution. Together with each batch of six samples, one reagent blank was included. Detection limits were 0.002/zg g-l for copper and 0.001 #g g-i for zinc. The accuracy and precision of the analytical
methods were tested with standard reference materials (NBS-bovine liver, SRM 1577). The mean recovery rates were 97.2% for zinc and 95.3% for copper. Statistical differences were evaluated by the Kruskal-Wallis one-way analysis of variance. A probability value of P < 0.05 was accepted as significant. 3. Results
Serum and urinary zinc and copper levels classified by sex are given in Table 1. Serum zinc
Table 3 The effect of various factors on the zinc and copper concentrations in serum (#g dl -l) of a general population a Factor
Place of residence Industrial area Rural area Blood pressure Normotensives b Hypertensives c Smoking habits Non-smokers < 10 cig. day -l >10 cig. day -I Drinking habits Non-drinkers < 100 g day -I > 100 g day -~
Zinc
N
GM
GSD
P
115.4 109.9
120.2 110.3
NS
115.3 95.1
55.4 80.3
NS
116.6 109.7 100.1
98,2 87,6 93,2
121.6 95.0 97.9
100.5 83.7 82.3
Copper GM
GSD
P
302 132
83.2 87.2
0.1 0.2
381 53
84.6 80.7
70.4 70.2
<0.05
206 135 93
83.8 84.1 91.9
0.1 0.1 0.1
NS
<0.001
279 130 25
86.9 80.3 79.8
0.1 0.1 0.1
<0.05
<0.05
NS
aN, number of samples; GM, geometric mean; GSD, geometric standard deviation; NS, not significant (denotes P > 0.05). bSystolic pressure < 90 m m H g and diastolic pressure < 140 mmHg. CSystolic pressure > 90 m m H g and diastolic pressure > 140 mmHg.
70
M. Schuhmacher et al./ScL Total Environ. 148 (1994) 67-72
and copper concentrations, as well as copper urine levels in men were significantly lower than in women, while there was no significant differences in urine concentrations of zinc between both sexes. The geometric means and geometric standard deviations of the zinc and copper concentrations in serum and urine of the same people classified by age are shown in Table 2. There were no statistically significant differences in serum or urinary zinc and copper levels between the subjects of different age groups. Zinc and copper levels in serum with respect to different influencing factors are given in Table 3. Serum copper concentrations were significantly higher (P < 0.05) for people living in a rural area, than in an industrial area of Tarragona Province, whereas no differences were observed for serum zinc levels. On the other hand, blood pressure did not show any significant relation with the serum zinc and copper concentrations. In contrast, the consumption of alcohol significantly reduced the levels of zinc and copper in serum, while the consumption of tobacco only reduced significantly the concentrations of zinc in serum. Table 4 summarizes the effects of the previous environmental and habitual factors on the zinc
and copper levels in urine. The mean zinc and copper values did not vary (P > 0.05) between the different groups. A study of the correlation coefficients of Pearson showed a significant (P < 0.001) correlation of copper and zinc in urine (r = 0.6987), while in serum this correlation was lower (r = 0.0381). 4. Discussion The present study provides data on the zinc and copper levels in serum and urine of a general population, living either in an industrial or in a rural area, from Tarragona Province (Spain). The geometric mean concentrations of serum zinc and copper found in this investigation were 113.9 and 84 ttg dl -l, respectively, whereas the mean values for urine zinc and copper concentrations were 698.7 and 26.6/~g g-i creatinine. The results obtained were compared with several available literature data (see Table 5). The mean levels for serum zinc were slightly higher than previously reported values [9,15-17], although they were remarkably lower than the levels found by Khandekar et al. [18] in the blood of an urban population of Bombay (India). The copper concentrations in serum
Table 4 The effect of various factors on the zinc and copper concentrations in urine (~g g - l creatinine) of a general population a Factor
Zinc GM
Place of residence Industrial area Rural area Blood pressure Normotensives b Hypertensives c Smoking habits Non-smokers < 10 cig. day -l > 10 cig. day -I Drinking habits Non-drinkers < 100 g day -l > 100 g day -I
N GSD
P
653.9 789.4
359.2 206.1
NS
692.7 795.0
550.2 596.6
NS
656.9 718.2 1027.5
589.4 620.4 798.8
655.8 765.5 816.3
470.7 450.5 490.8
Copper GM
GSD
P
302 132
27.0 25.6
14.7 5.4
NS
381 53
26.4 29.4
11.4 11.5
NS
NS
206 135 93
34.6 20.8 14.1
18.5 6.2 3.5
NS
NS
279 130 25
31.1 21.9 17.4
15.6 5.3 4.9
NS
aN, number of samples; GM, geometric mean; GSD, geometric standard deviation; NS, not significant (denotes P > 0.05). bSystolic pressure < 90 m m H g and diastolic pressure < 140 mmHg. cSystolic pressure > 90 m m H g and diastolic pressure > 140 mmHg.
M. Schuhmacher et al./ScL Total Environ. 148 (1994) 67-72
71
Table 5 Summary of studies reporting zinc and copper levels in serum and urine from populations of different countries a Reference
Zinc in serum (t~g dl -I)
This study
113.9
lyengar (1987)
80-110
Khandekar et al. (1987)
484.2
Komleh et al. (1990)
101.5
Zinc in urine 698.7 791 (tzg 1-~) 400-600 (t~g l -I)
Copper in serum (/~g dl -~) 84.3 80-110 (M) 110-140 (F)
Copper in urine
Remarks
26.6 39.0 (txg 1-I) 30-60 (~g l -I)
GM, M + F, N.E. Spain 16-65 years Range, M + F, different countries reference (frequent) values. GM, M + F, Bombay (India) blood levels, childrens and adults. AM, M + F. India, normal subjects. AM, M + F, India, stone formers. AM, M + F, Finland, 3-18 years. AM, F, Japan, 30-70 years. Range (AM), M + F Japanese children. AM, M, Italy, normotensives.
96.2
--
791 (ug 1-I)
91.7
55.6 (/~g 1-1)
94.3
1155 (u-g 1-I)
88.5
38.5 (~.g 1-I)
Laitinen et al. (1988)
95.1
--
Nogawa et al. (1984) Ohtake and Tamura (1976) Vivoli et al. (1987)
111.2
--
84-92 310-460 62-127 (92) - -
105-116 70-164 (109)
17.5-31
90.3
113.1
342.9
9.2
aLevels of zinc and copper in urine are expressed as t~g g-I creatinine or as remarked. AM, arithmetic mean; GM, geometric mean; M, males; F, females.
were slightly lower than previously reported data I9,15-17,19]. In general terms, the serum concentrations of zinc and copper obtained in this study, as well as the urinary levels of both metals, fit quite well into the frequent (reference) values of serum and urine concentrations of zinc and copper reported by Iyengar [19], who examined a large collection of data from whole or partial data from 40 countries of the global regions of Africa, Asia, Europe, North, South and Central America, Australia and New Zealand. As seen for several elements, it was concluded that both diet and environment exert a strong influence on the trace-element distribution pattern in tissues and body fluids [19]. The sex was a variable with a significant influence on the serum and urinary copper levels, as well as on the serum zinc concentrations. Females showed higher levels than males, which is in agreement with the previous results reported by Iyengar [19] for serum copper concentrations. In a previous investigation performed in the same areas, we found that hair
zinc and copper levels were also significantly higher in females than in males [12]. With regard to the place of residence, significant differences (P < 0.05) were only seen in serum copper concentrations, which were higher for the population living in the rural area. This was probably due to the fact that the consumption of copper through the diet is higher in the rural than in the industrial area [13]. On the other hand, blood pressure had no significant influence on the serum and urinary zinc and copper concentrations. Although mean values of serum and urinary levels of copper tended to increase with age, the differences were not statistically significant. In contrast, the concentrations of zinc in urine and serum tended to decrease with age but without significant differences among groups (P > 0.05). The values of zinc and copper in urine, as well as the levels of copper in serum were not affected by the smoking habits. There was, however, a significant decrease in serum zinc concentrations corresponding to a higher consumption of tobacco,
72
which implies a higher excretion (P > 0.05) of this metal in the urine. Similar results were reported by Vivoli et al. [20]. Serum zinc and copper concentrations were significantly affected by the drinking habits of the population studied. Thus, drinkers showed lower levels of both metals that non-drinkers. It has been reported that the consumption of alcohol may provoke zinc and copper deficiencies [5,21,22]. With regard to urinary excretion of zinc, although it has been demonstrated that the excretion of this metal is notorious in people consuming high quantities of alcohol [5,23], no significant differences were observed between drinkers and non-drinkers in this study. According to the above results, neither the dietary (deficit or excess of zinc and copper) nor the environmental exposure to these metals would imply serious health hazards for the population living in Tarragona Province.
M. Schuhmacher et al./Sci. Total Environ. 148 (1994) 67-72
8
9
10
II 12
13
14
15
5. Acknowledgements This work was supported by the Tarragona County Council (Catalonia, Spain). The authors thank the Servei d'Espectroscopia, University of Barcelona, for excellent technical assistance.
16
17
6. References 1 J.O. Nriagu, A silent epidemic of environmental metal poisoning? Environ. Pollut., 50 (1988) 139-161. 2 J.O. Nriagu and J.M. Pacyna, Quantitative assessment of worldwide contamination of air, water and soils by trace metals, Nature, 333 (1988) 134-139. 3 S. Takfics and A. Tatfir, Trace elements in the environment and in human organs. I. Methods and results, Environ. Res., 42 (1987) 312-320. 4 G. lngrao, P. Belloni, S. Di Pietro and G.P Santaroni, Levels of some trace elements in selected autopsy organs, and in hair and blood samples from adult subjects of the Italian population, Biol. Trace Elem. Res., 26 (1990) 699-708. 5 A.S. Prasad, Clinical, biochemical and pharmacological role of zinc, Ann. Rev. Pharmacol. Toxicol. 20 (1979) 393-426. 6 A.S. Prasad, Clinical manifestations of zinc deficiency. Annu. Rev. Nutr., 5 (1985) 341-363. 7 A.B, AbdeI-Mageed and F.W. Oehme, A review of the biochemical roles, toxicity and interactions of zinc, copper and iron. I. Zinc, Vet. Hum. Toxicol., 32 (1990) 34-39.
18
19
20
21
22
23
A. L6onard, G.B. Gerber and F. IAonard, Mutagenicity, carcinogenicity, and teratogenicity of zinc, Mutat. Res., 168 (1986) 343-353. M. Ohtake and T. Tamura, Serum zinc and copper levels in healthy Japanese children, Tohoku J. Exp. Med., 120 (1976) 99-103. A.B. AbdeI-Mageed and F.W. Oehme, A review of the biochemical roles, toxicity and interactions of zinc, copper and iron. II. Copper, Vet. Hum. Toxicol., 32 (1990) 230-234. H.F. Loyke, Copper and zinc in experimental hypertension, Biol. Trace Elem. Res., 29 (1991) 45-49. M. Schuhmacher, J.L. Domingo, J.M. Llobet, J. Corbella and J.B. Marti, Chromium, copper and zinc concentrations in hair of school children from southern Catalonia, Spain, Trace Elem. Med., 10 (1993) 21-26. M. Schuhmacher, J.L. Domingo, J.M. Llobct and J. Corbella, Dietary intake of copper, chromium and zinc in Tarragona Province, Spain, Sci. Total Environ., 132 (1993) 3-10. M. Schuhmacher, J.L. Domingo, J.M. LIobet and J. Corbella, Lead in children's hair as related to exposure in Tarragona Province, Spain, Sci. Total Environ., 104 (1991) 167-173. K. Nogawa, Y. Yamada, R. Honda, 1. Tsuritani, E. Kobayashi and M. Ishizaki, Copper and zinc levels in serum and urine of cadmium-exposed people with special reference to renal tubular damage, Environ. Res., 33 (1984) 29-38. K. Komleh, P. Hada, A.K. Pendse and P.P. Singh, Zinc, copper and manganese in serum, urine and stones, Int. Urol. Nephrol., 22 (1990) 113-118. R. Laitinen, E. Vuori and H.K. Akerblom, Hair zinc and copper: relationship to hair type and serum concentrations in children and adolescents, Biol. Trace Elem. Res., 16 (1988) 227-237. R.N. Khandekar, R. Raghunath and U.C. Mishra, Levels of lead, cadmium, zinc and copper in the blood of an urban population, Sci. Total Environ., 66 (1987) 185-191. G.V. lyengar, Reference values for the concentrations of As, Cd, Co, Cr, Cu, Fe, l, Hg, Mn, Mo, Ni, Pb, Se, and Zn in selected human tissues and body fluids, Biol. Trace Elem. Res., 12 (1987)263-295. G. Vivoli, P. Borella, M. Bergomi and G. Fantuzzi, Zinc and copper levels in serum, urine, and hair of humans in relation to blood pressure, Sci. Total Environ., 66 (1987) 55-64. K. Weismann, J. Roed-Petersen, N. Hjorth and H. Kopp, Chronic zinc deficiency syndrome in a beer drinker with a Billroth I1 resection, Int. J. Dermatol., 15 (1976) 757-761. M. Fields and C.G. Lewis, Alcohol consumption aggravates copper deficiency, Metabolism, 39 (1990) 610-613. J.G. Allan, G.S. Fell and R.I. Russell, Urinary zinc in hepatic cirrhosis, Scot. Med. J., 109 (1975) 109-111.
The Science of the Total Environment 148 (1994) 67-72
Zinc and copper levels in serum and urine: relationship to biological, habitual and environmental factors M. Schuhmacher
a, J . L . D o m i n g o *a'b, J. C o r b e l l a b
ULaboratory of Toxicology and Biochemistry, School of Medicine, Rovira i Virgili University, 43201 Reus, Spain hDepartment of Toxicology, University of Barcelona, 08036 Barcelona, Spain
(Received 15 February 1993; accepted 18 April 1993)
Abstract Zinc and copper levels were determined in serum and urine of 434 subjects living in an industrial and an agricultural area of Tarragona Province, Spain. Zinc and copper concentrations were related to a range of factors such as sex, age, blood pressure, and drinking and smoking habits. Geometric mean serum zinc and copper concentrations were, respectively, 113.9 and 84 ~g dl -I, while the mean values for urine zinc and copper concentrations were 698.7 and 26.6/~g g-J creatinine. Serum zinc and copper levels and urine copper concentrations in men were significantly lower than in women, while there were no differences in serum or urinary zinc and copper levels with age. The consumption of alcohol significantly reduced the levels of zinc and copper in serum, whereas blood pressure had no influence on these values. The levels of zinc and copper in urine were not affected by the smoking and drinking habits, place of residence, or blood pressure. In general terms, the results of this study agree with previously reported values from different countries. Key words: Zinc levels: Copper levels; Serum; Urine; Spanish population
1. Introduction Metals are released into the environment from a wide spectrum o f natural and anthropogenic sources [1]. The greatly increased circulation o f metals through the air, water and soils, and their inevitable transfer to the h u m a n food chain remains an important environmental issue which entails some u n k n o w n health risks for future generations [2]. Some of these metals (lead, cadmium, * Corresponding author.
mercury) are clearly toxic, while other such as zinc, copper, iron, manganese, etc. are essential for animals and h u m a n beings. Nevertheless, the beneficial biological effect o f an element depends on its concentration in the organism. Thus, both the absence and the excess o f essential microelements may produce undesirable effects [3,4]. Zinc is essential for the biological functions o f all living matter, e.g. for growth, testicular maturation, skin integrity, mental activity, w o u n d healing and immunocompetence. Zinc is also required for the metabolic activities o f over 70 metalloenzymes
0048-9697/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved. SSDI 0048-9697(93)03720-M
68
M. Schuhmacher et al. / Sci. Total Environ. 148 (1994) 67-72
[5-7]. In contrast, toxicity of zinc is low; however, some toxic effects in humans have been reported
2. Materials and methods
[5,81.
Two hundred and fifty-one men and 183 women (ages between 16 and 65 years) were the target subjects in this work. Only those who were not occupationally exposed to zinc and copper were included. Extensive descriptions of the study areas were recently reported [12-14]. Blood samples were drawn with special care by venipuncture, using cleaned syringes and stainless steel hypodermic needles, into nitric acid-cleaned glass tubes. Serum samples were then obtained by centrifugation and were kept frozen at -20°C until analysis. The urine was collected as a spot sample in polypropylene bottles treated beforehand with 10% nitric acid. Each urine sample was maintained by freezing at -20°C until analyses were performed. A questionnaire including sex, age, occupation, smoking and drinking habits, medications, as well as previous hepatic or renal diseases was filled up by the participants in the study. Blood pressure was also measured and recorded. Serum and urine samples of 1 ml were predigested with 2 ml of 65% nitric acid (Suprapur grade, Merck, Darmstadt, FRG) at room temperature for 12 h. The predigested samples were then heated at 110°C for 6 h, and subsequently at 150°C until the ashing procedure was completed. After cooling, ashed samples were diluted with 0.1 M nitric acid to 10 ml and kept in polypropylene bottles. All
Copper is also an important factor for several enzyme systems and is involved in the mobilization and release of storage iron from liver, the formation of myelin and bone, the maintenance of elastin in great blood vessels, and like zinc, is important in maintaining blood pressure [9-11]. Although copper toxicity in humans is rather rare, it can be toxic in man, producing nausea, vomiting, diarrhea and malaise [10]. Two frequently used indicators for body zinc and copper status are hair and serum concentrations. In a recent study performed in an industrial and a rural area of Tarragona Province (southern Catalonia, Spain), the concentrations of zinc and copper were determined in 302 hair samples of children living in these areas [12]. The aim of the present study was to establish the reference range of zinc and copper concentrations in serum and urine of people living in Tarragona Province. The northern area of this province is basically industrial, while the southern area is essentially agricultural. According to previous investigations, people living in both areas are exposed to low levels of zinc and copper through the food chain [13]. The effects of sex, age, smoking and drinking habits, and blood pressure on serum and urine zinc and copper levels were also evaluated.
Table 1 Zinc and copper levels in serum and urine of a general population, classified by sex a Sex
P
Men
Zinc Serum (/zg dl -j) Urine (/zg g-l Creat.) Copper Serum (/zg dl -t) Urine (ttg g-I Creat.)
Women
N
GM
GSD
N
GM
GSD
196 241
106.3 782.1
98.7 600.9
175 177
123.1 598.8
102.3 464.2
<0.001 NS
248 251
77.7 18.0
0.1 5.1
183 183
94.3 45.2
0.2 23.4
<0.001 <0.05
aN, number of samples analyzed; GM, geometric mean; GSD, geometric standard deviation; NS, not significant (denotes P > 0.05).
69
M. Schuhmacher et al./ Sci. Total Environ. 148 (1994) 67-72 Table 2 Zinc and copper levels in serum and urine of a general population, classified by age a Age (years)
N Zinc Serum (#g dl -I) Urine (p.g g-I Creat.) Copper Serum (p,g dl -I) Urine (/zg g-I Creat.)
16-25
26-35
36-45
111
152
82
46-55
56-65
54
26
128.8 4. 98.1 719.9 4. 650.5
119.1 4. 86.0 830.6 4. 710.4
98.1 4. 83.7 549.4 4. 322.0
102.8 4. 89.6 704.6 4. 514.7
105.1 ± 79.1 430.0 4- 383.5
79.8 4. 0.1 27.1 q- 10.8
87.1 4. 0.2 16.2 4. 5.0
88.8 4. 0.1 45.2 4. 33.1
77.0 q- 0.1 31.2 4. 6.4
90.3 ± 0.1 58,1 ± 25.9
aResults are presented as geometric means 4. geometric standard deviations. N, number of samples.
glassware and bottles were previously soaked in diluted nitric acid for 24 h and rinsed thoroughly with deionized distilled water. The zinc concentrations were measured by the flame atomic absorption spectrometry method only (Perk±n-Elmer 4000); copper levels were determined by inductively coupled plasma atomic emission spectrometry (Jobin Yvon 38 VHR). Three replicate determinations were made for each solution. Together with each batch of six samples, one reagent blank was included. Detection limits were 0.002/zg g-l for copper and 0.001 #g g-i for zinc. The accuracy and precision of the analytical
methods were tested with standard reference materials (NBS-bovine liver, SRM 1577). The mean recovery rates were 97.2% for zinc and 95.3% for copper. Statistical differences were evaluated by the Kruskal-Wallis one-way analysis of variance. A probability value of P < 0.05 was accepted as significant. 3. Results
Serum and urinary zinc and copper levels classified by sex are given in Table 1. Serum zinc
Table 3 The effect of various factors on the zinc and copper concentrations in serum (#g dl -l) of a general population a Factor
Place of residence Industrial area Rural area Blood pressure Normotensives b Hypertensives c Smoking habits Non-smokers < 10 cig. day -l >10 cig. day -I Drinking habits Non-drinkers < 100 g day -I > 100 g day -~
Zinc
N
GM
GSD
P
115.4 109.9
120.2 110.3
NS
115.3 95.1
55.4 80.3
NS
116.6 109.7 100.1
98,2 87,6 93,2
121.6 95.0 97.9
100.5 83.7 82.3
Copper GM
GSD
P
302 132
83.2 87.2
0.1 0.2
381 53
84.6 80.7
70.4 70.2
<0.05
206 135 93
83.8 84.1 91.9
0.1 0.1 0.1
NS
<0.001
279 130 25
86.9 80.3 79.8
0.1 0.1 0.1
<0.05
<0.05
NS
aN, number of samples; GM, geometric mean; GSD, geometric standard deviation; NS, not significant (denotes P > 0.05). bSystolic pressure < 90 m m H g and diastolic pressure < 140 mmHg. CSystolic pressure > 90 m m H g and diastolic pressure > 140 mmHg.
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M. Schuhmacher et al./ScL Total Environ. 148 (1994) 67-72
and copper concentrations, as well as copper urine levels in men were significantly lower than in women, while there was no significant differences in urine concentrations of zinc between both sexes. The geometric means and geometric standard deviations of the zinc and copper concentrations in serum and urine of the same people classified by age are shown in Table 2. There were no statistically significant differences in serum or urinary zinc and copper levels between the subjects of different age groups. Zinc and copper levels in serum with respect to different influencing factors are given in Table 3. Serum copper concentrations were significantly higher (P < 0.05) for people living in a rural area, than in an industrial area of Tarragona Province, whereas no differences were observed for serum zinc levels. On the other hand, blood pressure did not show any significant relation with the serum zinc and copper concentrations. In contrast, the consumption of alcohol significantly reduced the levels of zinc and copper in serum, while the consumption of tobacco only reduced significantly the concentrations of zinc in serum. Table 4 summarizes the effects of the previous environmental and habitual factors on the zinc
and copper levels in urine. The mean zinc and copper values did not vary (P > 0.05) between the different groups. A study of the correlation coefficients of Pearson showed a significant (P < 0.001) correlation of copper and zinc in urine (r = 0.6987), while in serum this correlation was lower (r = 0.0381). 4. Discussion The present study provides data on the zinc and copper levels in serum and urine of a general population, living either in an industrial or in a rural area, from Tarragona Province (Spain). The geometric mean concentrations of serum zinc and copper found in this investigation were 113.9 and 84 ttg dl -l, respectively, whereas the mean values for urine zinc and copper concentrations were 698.7 and 26.6/~g g-i creatinine. The results obtained were compared with several available literature data (see Table 5). The mean levels for serum zinc were slightly higher than previously reported values [9,15-17], although they were remarkably lower than the levels found by Khandekar et al. [18] in the blood of an urban population of Bombay (India). The copper concentrations in serum
Table 4 The effect of various factors on the zinc and copper concentrations in urine (~g g - l creatinine) of a general population a Factor
Zinc GM
Place of residence Industrial area Rural area Blood pressure Normotensives b Hypertensives c Smoking habits Non-smokers < 10 cig. day -l > 10 cig. day -I Drinking habits Non-drinkers < 100 g day -l > 100 g day -I
N GSD
P
653.9 789.4
359.2 206.1
NS
692.7 795.0
550.2 596.6
NS
656.9 718.2 1027.5
589.4 620.4 798.8
655.8 765.5 816.3
470.7 450.5 490.8
Copper GM
GSD
P
302 132
27.0 25.6
14.7 5.4
NS
381 53
26.4 29.4
11.4 11.5
NS
NS
206 135 93
34.6 20.8 14.1
18.5 6.2 3.5
NS
NS
279 130 25
31.1 21.9 17.4
15.6 5.3 4.9
NS
aN, number of samples; GM, geometric mean; GSD, geometric standard deviation; NS, not significant (denotes P > 0.05). bSystolic pressure < 90 m m H g and diastolic pressure < 140 mmHg. cSystolic pressure > 90 m m H g and diastolic pressure > 140 mmHg.
M. Schuhmacher et al./ScL Total Environ. 148 (1994) 67-72
71
Table 5 Summary of studies reporting zinc and copper levels in serum and urine from populations of different countries a Reference
Zinc in serum (t~g dl -I)
This study
113.9
lyengar (1987)
80-110
Khandekar et al. (1987)
484.2
Komleh et al. (1990)
101.5
Zinc in urine 698.7 791 (tzg 1-~) 400-600 (t~g l -I)
Copper in serum (/~g dl -~) 84.3 80-110 (M) 110-140 (F)
Copper in urine
Remarks
26.6 39.0 (txg 1-I) 30-60 (~g l -I)
GM, M + F, N.E. Spain 16-65 years Range, M + F, different countries reference (frequent) values. GM, M + F, Bombay (India) blood levels, childrens and adults. AM, M + F. India, normal subjects. AM, M + F, India, stone formers. AM, M + F, Finland, 3-18 years. AM, F, Japan, 30-70 years. Range (AM), M + F Japanese children. AM, M, Italy, normotensives.
96.2
--
791 (ug 1-I)
91.7
55.6 (/~g 1-1)
94.3
1155 (u-g 1-I)
88.5
38.5 (~.g 1-I)
Laitinen et al. (1988)
95.1
--
Nogawa et al. (1984) Ohtake and Tamura (1976) Vivoli et al. (1987)
111.2
--
84-92 310-460 62-127 (92) - -
105-116 70-164 (109)
17.5-31
90.3
113.1
342.9
9.2
aLevels of zinc and copper in urine are expressed as t~g g-I creatinine or as remarked. AM, arithmetic mean; GM, geometric mean; M, males; F, females.
were slightly lower than previously reported data I9,15-17,19]. In general terms, the serum concentrations of zinc and copper obtained in this study, as well as the urinary levels of both metals, fit quite well into the frequent (reference) values of serum and urine concentrations of zinc and copper reported by Iyengar [19], who examined a large collection of data from whole or partial data from 40 countries of the global regions of Africa, Asia, Europe, North, South and Central America, Australia and New Zealand. As seen for several elements, it was concluded that both diet and environment exert a strong influence on the trace-element distribution pattern in tissues and body fluids [19]. The sex was a variable with a significant influence on the serum and urinary copper levels, as well as on the serum zinc concentrations. Females showed higher levels than males, which is in agreement with the previous results reported by Iyengar [19] for serum copper concentrations. In a previous investigation performed in the same areas, we found that hair
zinc and copper levels were also significantly higher in females than in males [12]. With regard to the place of residence, significant differences (P < 0.05) were only seen in serum copper concentrations, which were higher for the population living in the rural area. This was probably due to the fact that the consumption of copper through the diet is higher in the rural than in the industrial area [13]. On the other hand, blood pressure had no significant influence on the serum and urinary zinc and copper concentrations. Although mean values of serum and urinary levels of copper tended to increase with age, the differences were not statistically significant. In contrast, the concentrations of zinc in urine and serum tended to decrease with age but without significant differences among groups (P > 0.05). The values of zinc and copper in urine, as well as the levels of copper in serum were not affected by the smoking habits. There was, however, a significant decrease in serum zinc concentrations corresponding to a higher consumption of tobacco,
72
which implies a higher excretion (P > 0.05) of this metal in the urine. Similar results were reported by Vivoli et al. [20]. Serum zinc and copper concentrations were significantly affected by the drinking habits of the population studied. Thus, drinkers showed lower levels of both metals that non-drinkers. It has been reported that the consumption of alcohol may provoke zinc and copper deficiencies [5,21,22]. With regard to urinary excretion of zinc, although it has been demonstrated that the excretion of this metal is notorious in people consuming high quantities of alcohol [5,23], no significant differences were observed between drinkers and non-drinkers in this study. According to the above results, neither the dietary (deficit or excess of zinc and copper) nor the environmental exposure to these metals would imply serious health hazards for the population living in Tarragona Province.
M. Schuhmacher et al./Sci. Total Environ. 148 (1994) 67-72
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9
10
II 12
13
14
15
5. Acknowledgements This work was supported by the Tarragona County Council (Catalonia, Spain). The authors thank the Servei d'Espectroscopia, University of Barcelona, for excellent technical assistance.
16
17
6. References 1 J.O. Nriagu, A silent epidemic of environmental metal poisoning? Environ. Pollut., 50 (1988) 139-161. 2 J.O. Nriagu and J.M. Pacyna, Quantitative assessment of worldwide contamination of air, water and soils by trace metals, Nature, 333 (1988) 134-139. 3 S. Takfics and A. Tatfir, Trace elements in the environment and in human organs. I. Methods and results, Environ. Res., 42 (1987) 312-320. 4 G. lngrao, P. Belloni, S. Di Pietro and G.P Santaroni, Levels of some trace elements in selected autopsy organs, and in hair and blood samples from adult subjects of the Italian population, Biol. Trace Elem. Res., 26 (1990) 699-708. 5 A.S. Prasad, Clinical, biochemical and pharmacological role of zinc, Ann. Rev. Pharmacol. Toxicol. 20 (1979) 393-426. 6 A.S. Prasad, Clinical manifestations of zinc deficiency. Annu. Rev. Nutr., 5 (1985) 341-363. 7 A.B, AbdeI-Mageed and F.W. Oehme, A review of the biochemical roles, toxicity and interactions of zinc, copper and iron. I. Zinc, Vet. Hum. Toxicol., 32 (1990) 34-39.
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A. L6onard, G.B. Gerber and F. IAonard, Mutagenicity, carcinogenicity, and teratogenicity of zinc, Mutat. Res., 168 (1986) 343-353. M. Ohtake and T. Tamura, Serum zinc and copper levels in healthy Japanese children, Tohoku J. Exp. Med., 120 (1976) 99-103. A.B. AbdeI-Mageed and F.W. Oehme, A review of the biochemical roles, toxicity and interactions of zinc, copper and iron. II. Copper, Vet. Hum. Toxicol., 32 (1990) 230-234. H.F. Loyke, Copper and zinc in experimental hypertension, Biol. Trace Elem. Res., 29 (1991) 45-49. M. Schuhmacher, J.L. Domingo, J.M. Llobet, J. Corbella and J.B. Marti, Chromium, copper and zinc concentrations in hair of school children from southern Catalonia, Spain, Trace Elem. Med., 10 (1993) 21-26. M. Schuhmacher, J.L. Domingo, J.M. Llobct and J. Corbella, Dietary intake of copper, chromium and zinc in Tarragona Province, Spain, Sci. Total Environ., 132 (1993) 3-10. M. Schuhmacher, J.L. Domingo, J.M. LIobet and J. Corbella, Lead in children's hair as related to exposure in Tarragona Province, Spain, Sci. Total Environ., 104 (1991) 167-173. K. Nogawa, Y. Yamada, R. Honda, 1. Tsuritani, E. Kobayashi and M. Ishizaki, Copper and zinc levels in serum and urine of cadmium-exposed people with special reference to renal tubular damage, Environ. Res., 33 (1984) 29-38. K. Komleh, P. Hada, A.K. Pendse and P.P. Singh, Zinc, copper and manganese in serum, urine and stones, Int. Urol. Nephrol., 22 (1990) 113-118. R. Laitinen, E. Vuori and H.K. Akerblom, Hair zinc and copper: relationship to hair type and serum concentrations in children and adolescents, Biol. Trace Elem. Res., 16 (1988) 227-237. R.N. Khandekar, R. Raghunath and U.C. Mishra, Levels of lead, cadmium, zinc and copper in the blood of an urban population, Sci. Total Environ., 66 (1987) 185-191. G.V. lyengar, Reference values for the concentrations of As, Cd, Co, Cr, Cu, Fe, l, Hg, Mn, Mo, Ni, Pb, Se, and Zn in selected human tissues and body fluids, Biol. Trace Elem. Res., 12 (1987)263-295. G. Vivoli, P. Borella, M. Bergomi and G. Fantuzzi, Zinc and copper levels in serum, urine, and hair of humans in relation to blood pressure, Sci. Total Environ., 66 (1987) 55-64. K. Weismann, J. Roed-Petersen, N. Hjorth and H. Kopp, Chronic zinc deficiency syndrome in a beer drinker with a Billroth I1 resection, Int. J. Dermatol., 15 (1976) 757-761. M. Fields and C.G. Lewis, Alcohol consumption aggravates copper deficiency, Metabolism, 39 (1990) 610-613. J.G. Allan, G.S. Fell and R.I. Russell, Urinary zinc in hepatic cirrhosis, Scot. Med. J., 109 (1975) 109-111.