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Occupational exposure of goldsmith workers of the area of Rome to potentially toxic metals as monitored through hair analysis
Microchemical Journal 67 Ž2000. 343᎐349
Occupational exposure of goldsmith workers of the area of Rome to potentially toxic metals as monitored through hair analysis S. D’Ilio, N. Violante, O. Senofonte, S. CaroliU Istituto Superiore di Sanita, ` Viale Regina Elena 299, 00161 Rome, Italy
Abstract In continuation of an investigation recently carried out to monitor through hair analysis the occupational exposure of goldsmith workers to potentially toxic elements, another study was performed to extend the same methodological approach to the goldsmiths of Rome. This research was part of the project P.R.O.Art. undertaken by the Italian National Research Council in cooperation with the Ministry of Industry and the National Craftsmen’s Federation with the purpose of supporting goldsmith activities and trade. Sampling of hair, washing and sample digestion followed well-established procedures. Silver, Au, Cd, Co, Cr, In, Ni, Pb and Pt were determined by means of inductively coupled plasma mass spectrometry ŽICP-MS., whereas Hg was analyzed using the flow injection mercury system ŽFIMS.. On the other hand, the expected relatively high concentrations of Cu and Zn in hair allowed for the use of inductively coupled plasma atomic emission spectrometry ŽICP-AES.. Data obtained were statistically treated by applying the non-parametric Kruskal᎐Wallis test. A significant difference, at the level of P- 0.05, between exposed and unexposed subjects in the Rome area was observed only for Au. 䊚 2000 Elsevier Science B.V. All rights reserved. Keywords: Hair analysis; Trace elements; Goldsmiths; Occupational exposure
1. Introduction Hair analysis can be regarded at as a non-invasive means of investigation and a powerful ap-
U
Corresponding author. Tel.: q39-6-4990-2052r2790; fax: q39-6-4990-2366. E-mail address: [email protected] ŽS. Caroli..
proach to assess health-affecting variations in the content of both essential and potentially toxic elements in human body. Such changes can be identified either by comparing the experimental data obtained in a given study with reference values available in the literature for a similar population, if any, with the data pertaining to selected subjects forming a reference group and included in the study w1᎐6x. Given its ability to
0026-265Xr00r$ - see front matter 䊚 2000 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 6 - 2 6 5 X Ž 0 0 . 0 0 0 8 6 - 2
344
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
accumulate elements in the keratinous structure, human hair can be considered as a reliable biological indicator of unbalances in the content of minerals in the human body, thus reflecting the health status of an individual as integrated over a period of several months w7᎐10x. Furthermore, it is worth stressing that this kind of matrix considerably simplifies the collection of specimens and their long-term storage. For all these merits, hair analysis has been recently applied to the determination of trace elements as regards individuals involved in goldsmith activities, in order to ascertain whether they were significantly exposed to potentially noxious metals as a consequence of the inhalation of hazardous dusts, fumes and vapors of inorganic chemicals freed in the environment during operations such as casting, machining, polishing, etc. The risk inherent in such activities should not be underestimated, as evidenced by the information gained in monitoring workers through the analysis of biological fluids, i.e. serum, blood and urine w11᎐15x. In continuation of the work already carried out for the areas of Valenza, Vicenza and Arezzo, the present study focused on the monitoring of a group of 33 exposed individuals and 11 control workers from a number of small- and mediumsized factories of gold articles of the urban area of Rome w16x. Elements to be investigated were chosen on the basis of their presence in the alloys of current use for goldsmith activities, namely, Ag, Au, Cd, Co, Cr, Cu, Hg, In, Ni, Pb, Pt and Zn.
2. Materials and methods Workers of the above-mentioned factories were selected as exposed subjects owing to their direct contact with the potentially toxic elements contained in the alloys used during the complete working cycle. On the other hand, non-exposed employees of the same companies were chosen as the controls. Moreover, just before sampling, personal data and details regarding, e.g. specific tasks carried out at the workplace, general state of health, diet habits, possible use of pharmaceuticals, alcohol, coffee and tobacco and, in particular, hair treatment, were obtained by filling in an
inquiry form for each worker. An amount of approximately 100᎐300 mg of hair were sampled for each subject from the occipital zone of the head at 1 cm from the scalp by using surgical scissors with tungsten carbide covered cutting edges, in order to avoid sample contamination from metals released through the friction exerted during sampling. Samples were then placed in polyethylene bags and stored in a desiccator in the dark until analysis. As regards preanalytical aspects, exogenous material was removed from the outer surface of hair by means of a well-established cleaning procedure that can be subdivided into three main steps, namely: Ži. washing with a mixture of 3:1 Žvrv. ethyl ether᎐acetone, three times for 10 min each, under continuous stirring, followed by drying in a oven at 50⬚C for approximately 15 min; Žii. soaking in a 5% EDTA ŽMerck, Darmstadt, Germany. solution for 1 h; and Žiii. rinsing three times with aliquots of high-purity de-ionized water ŽEasy Pure UV, International PBI, Milan, Italy.. After drying in an oven at 85⬚C for approximately 16 h, hair samples were weighed at the level of "0.1 mg and transferred into PTFE containers for the subsequent acid-assisted microwave ŽMW. oven digestion ŽMilestone mls ᎏ 1200 Mega, FKV Sorisole, Bergamo, Italy.. The solutions were left to stand overnight after addition of 2 ml HNO3 at room temperature in a chemical hood. One milliliter of HNO3 and 2 ml H 2 O 2 ŽMerck, Darmstadt, Germany. were then added. The MW settings were as follows: 3 min at 250 W followed by 6 min cooling; 5 min at 250 W with 5 min cooling; a further 5 min at 450 W and finally 5 min at 500 W. After appropriate cooling, the digested solutions were quantitatively transferred into polypropylene tubes with high-purity de-ionized water, then diluted up to 20 ml and stored in a refrigerator at q2⬚C. Quadrupole inductively coupled plasma mass spectrometry ŽQ-ICP-MS. was employed for the quantification of Ag, Au, Cd, Co, Cr, In, Ni, Pb and Pt. On the other hand, Cu and Zn had levels high enough to be analyzed by inductively coupled plasma atomic emission spectrometry ŽICPAES. ŽY was used as the internal standard.. Mercury, in turn, was analyzed using the flow injec-
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
345
Table 1 Apparatus and working conditions for Q-ICP-MS Spectrometer
Elan 5000 ŽPerkin-Elmer, Norwalk, CT, USA.
RF generator
Power output, 1.0 kW
Torch
Three-turn induction coil, with alumina injector
Argon flows Žl miny1 .
Plasma, 16; auxiliary, 0.9; aerosol, 1.0
Nebulizer
Cross-flow type, with Ryton Scott condensation chamber
Sampler
Ni, when Pt was measured, or Pt᎐Rh, when Ni was measured; orifice diameter, 1 mm
Skimmer
Ni, when Pt was measured, or Pt᎐Rh, when Ni was measured; orifice diameter, 1 mm
Sampling distance
20 mm from induction coil
Vacuum
Analytical, 1 = 10y5 % 1 = 10y3 Pa; intermediate Žbetween skimmer and sampler., approx. 1 = 102 Pa
Optimization
On masses of 24 Mg, 103 Rh and 208 Pb
Data acquisition
Replicate time, 1200 ms; dwell time, 100 ms; sweeps for reading, 4; readings for replicate, 3; number of replicates, 3; scanning mode, peak hop transient
Analytical masses
107
Ag, 197Au, 114 Cd, 59Co, 52 Cr, 115 In, 60 Ni, 204q206q207q208 Pb and 195 Pt
tion mercury system ŽFIMS., basically a cold-vapor atomic absorption spectrometry approach. The working conditions relevant to these three techniques are reported in Tables 1᎐3, respectively. The whole procedure was checked for accuracy by including in each analytical run the Certified Reference Material BCR CRM no. 397 Human Hair, although this is certified only for four elements out of the twelve under test.
3. Results and discussion The results of the accuracy test are set forth in Table 4, as averaged from the analysis of 12 independent aliquots. A good agreement with the certified values was found. The experimental data obtained for both ex-
posed individuals and controls were plotted as cumulative frequencies vs. the corresponding concentrations. On the basis of these curves, it was then decided to apply a statistical treatment only to those elements for which significant differences between exposed individuals and controls could be inferred from such visual representations. The graph of Fig. 1 illustrates the trend shown by Au, the only metal for which marked differences between exposed subjects and controls were confirmed. Most distributions were found to be characterized by a non-normal pattern, as confirmed by the Kolmogorov᎐Smirnov test. Moreover, the non-parametric Kruskal᎐Wallis test for unpaired values was also applied to evaluate the level of significance of the observed differences. Possible outliers were identified by the box-and-whisker plot approach. According to
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
346
Table 2 Apparatus and working conditions for ICP-AES Spectrometer
Optima 3100, axial view ŽPerkin-Elmer, Norwalk, CT, USA.
RF generator
Frequency, 40 MHz Žfree running.; power output, 1.3 kW
Induction coil
Four turns, o.d., 32 mm; height, 20 mm
Torch
Perkin-Elmer, mounted into a quick-change torch module
Nebulizer
Cross-flow type, with a Ryton Scott condensation chamber
Argon flows Žl miny1 .
Plasma, 16; auxiliary, 1.0; aerosol, 0.8
Optical system
Polychromator equipped with an echelle grating Žruling density, 79 lines mmy1 . combined with a Schmidt Cross-Disperser; detection by a simultaneous solid-state Segmented-array Charged-coupled device Detector ŽSCD.; wavelength range, 165᎐403 nm; maximum resolution, 0.006 nm at 200 nm
Spectral lines Žnm.
Cu ŽI., 324.8; Zn ŽI., 213.9; Y ŽII., 371.0 Žas the internal standard.
Table 3 Apparatus and working conditions for FIMS Spectrometer Lamp Slit Hg wavelength Argon flow Signal Mode Read time Sample dilution Reductant Carrier solution Loop volume
FIAS 400 ŽPerkin-Elmer, Norwalk, CT, USA. Hg EDL 0.7 nm 253.7 nm 70 ml miny1 Type, atomic absorption; measurement, peak height 15.00 s 1:1 in 3.0% Žvrv. HCl 0.2% NaBH4 in 0.05% NaOH 3.0% Žvrv. HCl 500 l
this procedure, outliers were detected as those data points more than three interquartile ranges below the first quartile or above the third quarTable 4 Accuracy data as obtained through the analysis of the BCR CRM no. 397 Human Hair Žn s 12. Element
Certified concentrations Žg gy1 .
Found concentrations Žg gy1 .
Cd Hg Pb Zn
0.521" 0.024 12.3" 0.5 33.0" 1.2 199 " 5
0.525" 0.029 12.7" 1.1 33.3" 1.2 203 " 11
tile. These values were omitted from the subsequent statistical evaluation of the results. Due to the elevated dispersion of data, the geometric means have been used instead of the arithmetic means. Geometric means, geometric standard deviations, medians, means, standard deviations and the level of significance of this test are shown in Table 5. As regards Cd, In and Pt, their concentrations were always below the limits of detection ŽLODs. afforded by the technique used, i.e. - 0.100, - 0.0005 and - 0.002 g ly1 , respectively. In the case of Cd, although for some samples concentration values higher than the LOD could be ob-
Element
Ag Au Co Cr Cu Hg Ni Pb Zn
Exposed subjects Ž n s 33. Žall values in g gy1 .
Control subjects Ž n s 11. Žall values in g gy1 .
Geometric mean "geometric S.D.
Median
Mean " S.D.
Geometric mean "geometric S.D.
Median
Mean " S.D.
Level of significance P
2.24" 2.95 2.03" 2.23 0.030" 0.035 0.257" 0.220 16.8" 11.3 2.06" 0.96 0.417" 0.367 1.26" 1.62 187 " 53
2.14 2.30 0.032 0.336 13.5 2.00 0.386 1.01 183
4.51" 5.19 3.88" 6.35 0.057" 0.072 0.345" 0.230 22.0" 20.3 2.30" 1.20 0.651" 0.917 3.30" 6.94 196 " 79
1.17" 1.55 0.93" 0.61 0.026" 0.023 0.336" 0.258 11.1" 4.4 2.33" 1.20 0.263" 0.217 0.49" 0.44 193 " 39
1.93 1.01 0.027 0.513 10.1 2.26 0.289 0.50 193
1.91" 1.51 1.12" 0.69 0.035" 0.025 0.415" 0.226 12.0 " 5.4 2.60" 1.17 0.345" 0.244 0.68" 0.55 197 " 40
0.189 0.031 0.904 0.293 0.227 0.323 0.195 0.106 0.456
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
Table 5 Figures of merit for the analysis of trace elements in human hair of goldsmith workers of the urban area of Rome
347
348
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
Fig. 1. Cumulative frequencies vs. the corresponding Au concentrations Žarea of Rome..
tained, this element was excluded from the statistical evaluation of data due to their paucity. Statistical treatment confirmed that there is no evidence of an appreciable exposure but in the case of Au, for which a significant difference at the level of P - 0.05 was detected between exposed individuals and controls. This apparent exposure to Au may depend on the fact that goldsmith activities in Rome are basically focused on the production of jewels and that the complete working cycle Žfrom melting to casting. is carried out by a single craftsman. Exposure to Au, apparently caused by a similar manufacturing activity, was previously observed also for the production area of Vicenza, where a marked difference was found between exposed and control subjects Ž P0.01.. These findings are much more reassuring than those achieved in the three areas investigated in a previous study w16x. In this context, in fact, it is worth mentioning that for the groups of exposed subjects of Valenza and Vicenza a clear accumulation of Ag was shown, with a significance level of P- 0.05 and P- 0.01, respectively. This fact is probably ascribable to the ability shown by this metal to deposit in microscopic granules around the hair follicles. Moreover, for Cu a significant difference between exposed and unexposed subjects was found only for the Vi-
cenza group Ž P- 0.01.. Of particular interest was also the case of In as the results obtained were supportive of an exposure to this element Ž P0.05.. This might well have been the consequence of the adoption of a new working procedure recommended by the local health authority which prescribes the replacement of Cd with In in the alloys used to manufacture gold objects. The Arezzo area, in turn, where the production is highly automated, was characterized by much lower levels of exposure with no significant differences being detected for the elements investigated. On the basis of the large number of samples analyzed during the overall project as well as of the results obtained in the present study, hair analysis may be regarded at as a powerful approach which complements the more traditional analysis of biological fluids, especially to monitor occupational exposure to potentially toxic trace elements. The project will be concluded by sampling hair from goldsmith workers of an area in southern Italy, i.e. Naples and surroundings.
Acknowledgements The authors gratefully acknowledge the finan-
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
cial support of the P.R.O.Art. research programme of the Italian National Research Council. References w1x M. Kamamura, Jpn. J. Hyg. 38 Ž1983. 823. w2x Y. Takey, S. Matsuda, S. Imai et al., Bull. Environ. Contam. Toxicol. 36 Ž1986. 793. w3x P. Manson, S. Zlotkin, Can. Med. Assoc. J. 133 Ž1985. 186᎐188. w4x S. Caroli, A. Alimonti, E. Coni, F. Petrucci, O. Senofonte, N. Violante, Crit. Rev. Anal. Chem. 24 Ž1994. 363᎐398. w5x S. Caroli, O. Senofonte, N. Violante, L. Fornarelli, A. Powar, Microchem. J. 46 Ž1992. 174᎐183. w6x O. Senofonte, N. Violante, L. Fornarelli, E. Beccaloni, A. Powar, S. Caroli, Ann. Ist. Super. Sanita ` 25 Ž3. Ž1989. 385᎐392.
349
w7x H.C. Hopps, Sci. Total Environ. 7 Ž1977. 71᎐89. w8x G.J. Evans, R.E.J. Jervis, Radioanal. Nucl. Chem. Art. 110 Ž1987. 613᎐625. w9x M. Laker, Lancet 2 Ž1982. 260᎐262. w10x L.D. Wilson ŽEd.., Nutritional Balancing and Hair Mineral Analysis. A Comprehensive Guide, L.D. Wilson Consultants, Inc., 1991, pp. 1᎐330. w11x R. Dubrow, D.M. Gute, Am. J. Ind. Med. 12 Ž1987. 579᎐593. w12x G.D. Kern, Am. J. Ind. Med. 25 Ž1994. 759᎐767. w13x J.R. Behari, S. Singh, S.K. Tandon, A.K. Wahal, Ann. Occup. Hyg. 27 Ž1. Ž1983. 107᎐109. w14x C. Minoia, M.C. Oppezzo, L. Pozzoli, G. Catenacci, E.G. Capodaglio, Ital. Med. Lav. 7 Ž1985. 65᎐73. w15x A. Margaret Samuel, P.J. Baxter, Br. J. Ind. Med. 43 Ž1986. 420᎐421. w16x S. Caroli, O. Senofonte, N. Violante et al., Microchem. J. 59 Ž1. Ž1998. 32᎐44.
Occupational exposure of goldsmith workers of the area of Rome to potentially toxic metals as monitored through hair analysis S. D’Ilio, N. Violante, O. Senofonte, S. CaroliU Istituto Superiore di Sanita, ` Viale Regina Elena 299, 00161 Rome, Italy
Abstract In continuation of an investigation recently carried out to monitor through hair analysis the occupational exposure of goldsmith workers to potentially toxic elements, another study was performed to extend the same methodological approach to the goldsmiths of Rome. This research was part of the project P.R.O.Art. undertaken by the Italian National Research Council in cooperation with the Ministry of Industry and the National Craftsmen’s Federation with the purpose of supporting goldsmith activities and trade. Sampling of hair, washing and sample digestion followed well-established procedures. Silver, Au, Cd, Co, Cr, In, Ni, Pb and Pt were determined by means of inductively coupled plasma mass spectrometry ŽICP-MS., whereas Hg was analyzed using the flow injection mercury system ŽFIMS.. On the other hand, the expected relatively high concentrations of Cu and Zn in hair allowed for the use of inductively coupled plasma atomic emission spectrometry ŽICP-AES.. Data obtained were statistically treated by applying the non-parametric Kruskal᎐Wallis test. A significant difference, at the level of P- 0.05, between exposed and unexposed subjects in the Rome area was observed only for Au. 䊚 2000 Elsevier Science B.V. All rights reserved. Keywords: Hair analysis; Trace elements; Goldsmiths; Occupational exposure
1. Introduction Hair analysis can be regarded at as a non-invasive means of investigation and a powerful ap-
U
Corresponding author. Tel.: q39-6-4990-2052r2790; fax: q39-6-4990-2366. E-mail address: [email protected] ŽS. Caroli..
proach to assess health-affecting variations in the content of both essential and potentially toxic elements in human body. Such changes can be identified either by comparing the experimental data obtained in a given study with reference values available in the literature for a similar population, if any, with the data pertaining to selected subjects forming a reference group and included in the study w1᎐6x. Given its ability to
0026-265Xr00r$ - see front matter 䊚 2000 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 6 - 2 6 5 X Ž 0 0 . 0 0 0 8 6 - 2
344
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
accumulate elements in the keratinous structure, human hair can be considered as a reliable biological indicator of unbalances in the content of minerals in the human body, thus reflecting the health status of an individual as integrated over a period of several months w7᎐10x. Furthermore, it is worth stressing that this kind of matrix considerably simplifies the collection of specimens and their long-term storage. For all these merits, hair analysis has been recently applied to the determination of trace elements as regards individuals involved in goldsmith activities, in order to ascertain whether they were significantly exposed to potentially noxious metals as a consequence of the inhalation of hazardous dusts, fumes and vapors of inorganic chemicals freed in the environment during operations such as casting, machining, polishing, etc. The risk inherent in such activities should not be underestimated, as evidenced by the information gained in monitoring workers through the analysis of biological fluids, i.e. serum, blood and urine w11᎐15x. In continuation of the work already carried out for the areas of Valenza, Vicenza and Arezzo, the present study focused on the monitoring of a group of 33 exposed individuals and 11 control workers from a number of small- and mediumsized factories of gold articles of the urban area of Rome w16x. Elements to be investigated were chosen on the basis of their presence in the alloys of current use for goldsmith activities, namely, Ag, Au, Cd, Co, Cr, Cu, Hg, In, Ni, Pb, Pt and Zn.
2. Materials and methods Workers of the above-mentioned factories were selected as exposed subjects owing to their direct contact with the potentially toxic elements contained in the alloys used during the complete working cycle. On the other hand, non-exposed employees of the same companies were chosen as the controls. Moreover, just before sampling, personal data and details regarding, e.g. specific tasks carried out at the workplace, general state of health, diet habits, possible use of pharmaceuticals, alcohol, coffee and tobacco and, in particular, hair treatment, were obtained by filling in an
inquiry form for each worker. An amount of approximately 100᎐300 mg of hair were sampled for each subject from the occipital zone of the head at 1 cm from the scalp by using surgical scissors with tungsten carbide covered cutting edges, in order to avoid sample contamination from metals released through the friction exerted during sampling. Samples were then placed in polyethylene bags and stored in a desiccator in the dark until analysis. As regards preanalytical aspects, exogenous material was removed from the outer surface of hair by means of a well-established cleaning procedure that can be subdivided into three main steps, namely: Ži. washing with a mixture of 3:1 Žvrv. ethyl ether᎐acetone, three times for 10 min each, under continuous stirring, followed by drying in a oven at 50⬚C for approximately 15 min; Žii. soaking in a 5% EDTA ŽMerck, Darmstadt, Germany. solution for 1 h; and Žiii. rinsing three times with aliquots of high-purity de-ionized water ŽEasy Pure UV, International PBI, Milan, Italy.. After drying in an oven at 85⬚C for approximately 16 h, hair samples were weighed at the level of "0.1 mg and transferred into PTFE containers for the subsequent acid-assisted microwave ŽMW. oven digestion ŽMilestone mls ᎏ 1200 Mega, FKV Sorisole, Bergamo, Italy.. The solutions were left to stand overnight after addition of 2 ml HNO3 at room temperature in a chemical hood. One milliliter of HNO3 and 2 ml H 2 O 2 ŽMerck, Darmstadt, Germany. were then added. The MW settings were as follows: 3 min at 250 W followed by 6 min cooling; 5 min at 250 W with 5 min cooling; a further 5 min at 450 W and finally 5 min at 500 W. After appropriate cooling, the digested solutions were quantitatively transferred into polypropylene tubes with high-purity de-ionized water, then diluted up to 20 ml and stored in a refrigerator at q2⬚C. Quadrupole inductively coupled plasma mass spectrometry ŽQ-ICP-MS. was employed for the quantification of Ag, Au, Cd, Co, Cr, In, Ni, Pb and Pt. On the other hand, Cu and Zn had levels high enough to be analyzed by inductively coupled plasma atomic emission spectrometry ŽICPAES. ŽY was used as the internal standard.. Mercury, in turn, was analyzed using the flow injec-
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
345
Table 1 Apparatus and working conditions for Q-ICP-MS Spectrometer
Elan 5000 ŽPerkin-Elmer, Norwalk, CT, USA.
RF generator
Power output, 1.0 kW
Torch
Three-turn induction coil, with alumina injector
Argon flows Žl miny1 .
Plasma, 16; auxiliary, 0.9; aerosol, 1.0
Nebulizer
Cross-flow type, with Ryton Scott condensation chamber
Sampler
Ni, when Pt was measured, or Pt᎐Rh, when Ni was measured; orifice diameter, 1 mm
Skimmer
Ni, when Pt was measured, or Pt᎐Rh, when Ni was measured; orifice diameter, 1 mm
Sampling distance
20 mm from induction coil
Vacuum
Analytical, 1 = 10y5 % 1 = 10y3 Pa; intermediate Žbetween skimmer and sampler., approx. 1 = 102 Pa
Optimization
On masses of 24 Mg, 103 Rh and 208 Pb
Data acquisition
Replicate time, 1200 ms; dwell time, 100 ms; sweeps for reading, 4; readings for replicate, 3; number of replicates, 3; scanning mode, peak hop transient
Analytical masses
107
Ag, 197Au, 114 Cd, 59Co, 52 Cr, 115 In, 60 Ni, 204q206q207q208 Pb and 195 Pt
tion mercury system ŽFIMS., basically a cold-vapor atomic absorption spectrometry approach. The working conditions relevant to these three techniques are reported in Tables 1᎐3, respectively. The whole procedure was checked for accuracy by including in each analytical run the Certified Reference Material BCR CRM no. 397 Human Hair, although this is certified only for four elements out of the twelve under test.
3. Results and discussion The results of the accuracy test are set forth in Table 4, as averaged from the analysis of 12 independent aliquots. A good agreement with the certified values was found. The experimental data obtained for both ex-
posed individuals and controls were plotted as cumulative frequencies vs. the corresponding concentrations. On the basis of these curves, it was then decided to apply a statistical treatment only to those elements for which significant differences between exposed individuals and controls could be inferred from such visual representations. The graph of Fig. 1 illustrates the trend shown by Au, the only metal for which marked differences between exposed subjects and controls were confirmed. Most distributions were found to be characterized by a non-normal pattern, as confirmed by the Kolmogorov᎐Smirnov test. Moreover, the non-parametric Kruskal᎐Wallis test for unpaired values was also applied to evaluate the level of significance of the observed differences. Possible outliers were identified by the box-and-whisker plot approach. According to
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
346
Table 2 Apparatus and working conditions for ICP-AES Spectrometer
Optima 3100, axial view ŽPerkin-Elmer, Norwalk, CT, USA.
RF generator
Frequency, 40 MHz Žfree running.; power output, 1.3 kW
Induction coil
Four turns, o.d., 32 mm; height, 20 mm
Torch
Perkin-Elmer, mounted into a quick-change torch module
Nebulizer
Cross-flow type, with a Ryton Scott condensation chamber
Argon flows Žl miny1 .
Plasma, 16; auxiliary, 1.0; aerosol, 0.8
Optical system
Polychromator equipped with an echelle grating Žruling density, 79 lines mmy1 . combined with a Schmidt Cross-Disperser; detection by a simultaneous solid-state Segmented-array Charged-coupled device Detector ŽSCD.; wavelength range, 165᎐403 nm; maximum resolution, 0.006 nm at 200 nm
Spectral lines Žnm.
Cu ŽI., 324.8; Zn ŽI., 213.9; Y ŽII., 371.0 Žas the internal standard.
Table 3 Apparatus and working conditions for FIMS Spectrometer Lamp Slit Hg wavelength Argon flow Signal Mode Read time Sample dilution Reductant Carrier solution Loop volume
FIAS 400 ŽPerkin-Elmer, Norwalk, CT, USA. Hg EDL 0.7 nm 253.7 nm 70 ml miny1 Type, atomic absorption; measurement, peak height 15.00 s 1:1 in 3.0% Žvrv. HCl 0.2% NaBH4 in 0.05% NaOH 3.0% Žvrv. HCl 500 l
this procedure, outliers were detected as those data points more than three interquartile ranges below the first quartile or above the third quarTable 4 Accuracy data as obtained through the analysis of the BCR CRM no. 397 Human Hair Žn s 12. Element
Certified concentrations Žg gy1 .
Found concentrations Žg gy1 .
Cd Hg Pb Zn
0.521" 0.024 12.3" 0.5 33.0" 1.2 199 " 5
0.525" 0.029 12.7" 1.1 33.3" 1.2 203 " 11
tile. These values were omitted from the subsequent statistical evaluation of the results. Due to the elevated dispersion of data, the geometric means have been used instead of the arithmetic means. Geometric means, geometric standard deviations, medians, means, standard deviations and the level of significance of this test are shown in Table 5. As regards Cd, In and Pt, their concentrations were always below the limits of detection ŽLODs. afforded by the technique used, i.e. - 0.100, - 0.0005 and - 0.002 g ly1 , respectively. In the case of Cd, although for some samples concentration values higher than the LOD could be ob-
Element
Ag Au Co Cr Cu Hg Ni Pb Zn
Exposed subjects Ž n s 33. Žall values in g gy1 .
Control subjects Ž n s 11. Žall values in g gy1 .
Geometric mean "geometric S.D.
Median
Mean " S.D.
Geometric mean "geometric S.D.
Median
Mean " S.D.
Level of significance P
2.24" 2.95 2.03" 2.23 0.030" 0.035 0.257" 0.220 16.8" 11.3 2.06" 0.96 0.417" 0.367 1.26" 1.62 187 " 53
2.14 2.30 0.032 0.336 13.5 2.00 0.386 1.01 183
4.51" 5.19 3.88" 6.35 0.057" 0.072 0.345" 0.230 22.0" 20.3 2.30" 1.20 0.651" 0.917 3.30" 6.94 196 " 79
1.17" 1.55 0.93" 0.61 0.026" 0.023 0.336" 0.258 11.1" 4.4 2.33" 1.20 0.263" 0.217 0.49" 0.44 193 " 39
1.93 1.01 0.027 0.513 10.1 2.26 0.289 0.50 193
1.91" 1.51 1.12" 0.69 0.035" 0.025 0.415" 0.226 12.0 " 5.4 2.60" 1.17 0.345" 0.244 0.68" 0.55 197 " 40
0.189 0.031 0.904 0.293 0.227 0.323 0.195 0.106 0.456
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
Table 5 Figures of merit for the analysis of trace elements in human hair of goldsmith workers of the urban area of Rome
347
348
S. D’Ilio et al. r Microchemical Journal 67 (2000) 343᎐349
Fig. 1. Cumulative frequencies vs. the corresponding Au concentrations Žarea of Rome..
tained, this element was excluded from the statistical evaluation of data due to their paucity. Statistical treatment confirmed that there is no evidence of an appreciable exposure but in the case of Au, for which a significant difference at the level of P - 0.05 was detected between exposed individuals and controls. This apparent exposure to Au may depend on the fact that goldsmith activities in Rome are basically focused on the production of jewels and that the complete working cycle Žfrom melting to casting. is carried out by a single craftsman. Exposure to Au, apparently caused by a similar manufacturing activity, was previously observed also for the production area of Vicenza, where a marked difference was found between exposed and control subjects Ž P0.01.. These findings are much more reassuring than those achieved in the three areas investigated in a previous study w16x. In this context, in fact, it is worth mentioning that for the groups of exposed subjects of Valenza and Vicenza a clear accumulation of Ag was shown, with a significance level of P- 0.05 and P- 0.01, respectively. This fact is probably ascribable to the ability shown by this metal to deposit in microscopic granules around the hair follicles. Moreover, for Cu a significant difference between exposed and unexposed subjects was found only for the Vi-
cenza group Ž P- 0.01.. Of particular interest was also the case of In as the results obtained were supportive of an exposure to this element Ž P0.05.. This might well have been the consequence of the adoption of a new working procedure recommended by the local health authority which prescribes the replacement of Cd with In in the alloys used to manufacture gold objects. The Arezzo area, in turn, where the production is highly automated, was characterized by much lower levels of exposure with no significant differences being detected for the elements investigated. On the basis of the large number of samples analyzed during the overall project as well as of the results obtained in the present study, hair analysis may be regarded at as a powerful approach which complements the more traditional analysis of biological fluids, especially to monitor occupational exposure to potentially toxic trace elements. The project will be concluded by sampling hair from goldsmith workers of an area in southern Italy, i.e. Naples and surroundings.
Acknowledgements The authors gratefully acknowledge the finan-
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cial support of the P.R.O.Art. research programme of the Italian National Research Council. References w1x M. Kamamura, Jpn. J. Hyg. 38 Ž1983. 823. w2x Y. Takey, S. Matsuda, S. Imai et al., Bull. Environ. Contam. Toxicol. 36 Ž1986. 793. w3x P. Manson, S. Zlotkin, Can. Med. Assoc. J. 133 Ž1985. 186᎐188. w4x S. Caroli, A. Alimonti, E. Coni, F. Petrucci, O. Senofonte, N. Violante, Crit. Rev. Anal. Chem. 24 Ž1994. 363᎐398. w5x S. Caroli, O. Senofonte, N. Violante, L. Fornarelli, A. Powar, Microchem. J. 46 Ž1992. 174᎐183. w6x O. Senofonte, N. Violante, L. Fornarelli, E. Beccaloni, A. Powar, S. Caroli, Ann. Ist. Super. Sanita ` 25 Ž3. Ž1989. 385᎐392.
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w7x H.C. Hopps, Sci. Total Environ. 7 Ž1977. 71᎐89. w8x G.J. Evans, R.E.J. Jervis, Radioanal. Nucl. Chem. Art. 110 Ž1987. 613᎐625. w9x M. Laker, Lancet 2 Ž1982. 260᎐262. w10x L.D. Wilson ŽEd.., Nutritional Balancing and Hair Mineral Analysis. A Comprehensive Guide, L.D. Wilson Consultants, Inc., 1991, pp. 1᎐330. w11x R. Dubrow, D.M. Gute, Am. J. Ind. Med. 12 Ž1987. 579᎐593. w12x G.D. Kern, Am. J. Ind. Med. 25 Ž1994. 759᎐767. w13x J.R. Behari, S. Singh, S.K. Tandon, A.K. Wahal, Ann. Occup. Hyg. 27 Ž1. Ž1983. 107᎐109. w14x C. Minoia, M.C. Oppezzo, L. Pozzoli, G. Catenacci, E.G. Capodaglio, Ital. Med. Lav. 7 Ž1985. 65᎐73. w15x A. Margaret Samuel, P.J. Baxter, Br. J. Ind. Med. 43 Ž1986. 420᎐421. w16x S. Caroli, O. Senofonte, N. Violante et al., Microchem. J. 59 Ž1. Ž1998. 32᎐44.