Application of Inductively Coupled Plasma Mass Spectrometry ...

Journal of Analytical Toxicology, Vol. 33, March 2009

Application of Inductively Coupled Plasma Mass Spectrometry Multielement Analysis in Fingernail and Toenail as a Biomarker of Metal Exposure* J.P. Goullé1,2,†, E. Saussereau1, L. Mahieu1, D. Bouige3, S. Groenwont1, M. Guerbet2, and C. Lacroix1 1Laboratoire

de Toxicologie, Groupe Hospitalier, BP 24, 76083 Le Havre, France; 2Laboratoire de Toxicologie, Faculté de Médecine et de Pharmacie, 22 boulevard Gambetta, 76183 Rouen, France; and 3Laboratoire de Biochimie, Groupe Hospitalier, BP 24, 76083 Le Havre, France

Abstract The application of inductively coupled plasma mass spectrometry (ICP-MS) to multielement analysis in fingernail and toenail as biological indices for metal exposure is presented. The ICP-MS measurements were performed using a Thermo Elemental X7CCT series. Fingernail specimens were obtained from 130 healthy volunteers, and paired fingernail and toenail samples from 50 additional healthy volunteers of both sexes were collected as well. After warm water and acetone decontamination, 20 mg fingernails and toenails were acid mineralized after a decontamination procedure, and 32–34 elements were simultaneously quantified after acid dilution following water calibration. Li, Be, B, Al, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Mo, Pd, Ag, Cd, Sn, Sb, Te, Ba, La, Gd, W, Pt, Hg, Tl, Pb, Bi, and U could be validated in fingernail and toenail samples. Linearity was excellent, and the correlation coefficients were above 0.999. Quantification limits ranged from 0.04 pg/mg or ng/g (U) to 0.1 ng/mg or µg/g (B). Because of the lack of available certified nail reference material, an adequate quality assessment scheme was ensured by comparison with an interlaboratory nail-testing procedure, and the results showed optimal consistency for elements tested. Results are presented and compared with published multielement data. Six cases of domestic exposure to lead were diagnosed based on fingernail analysis. Application of ICP-MS multielement analysis in fingernail and toenail as a biomarker of metal and nonmetal exposure permits greater noninvasive control of industrial, domestic, or environmental exposure and is very useful for epidemiological studies.

Introduction In recent years, xenobiotic analysis of keratinized matrices like hair (1) or nails (2) have consistently increased, in addition * This work was partially presented at the 43rd TIAFT Meeting in Seattle, WA, August 26–30, 2007. † Author to whom correspondence and reprint requests should be addressed: Professor Jean-Pierre Goullé, Laboratoire de pharmacocinétique et de toxicologie cliniques, Groupe Hospitalier Jacques Monod, BP 24, 76083 Le Havre-Cedex, France. E-mail: [email protected].

92

to common use of biological fluids as blood and urine. As blood and urine reflects xenobiotic exposure based on a very short or limited period, i.e. hours for blood, days for urine; hair and nails reflect this exposure, after weeks or months. Many forensic and clinical applications have been proposed for various xenobiotics, drugs, or drugs of abuse in hair (1). Application of hair analysis to control metal workplace exposure has been tested unsuccessfully (3). However, some other applications of interest have been reported with various elements in hair. This concerns arsenic within a context of hydric arsenicism due to natural pollution in drinking water shown in hair or nails, as they retain the highest concentration of arsenic due to the content of keratin, a group of proteins containing disulfide bonds. In places such as West Bengal, India, arsenic water and food pollution have been responsible for various skin lesions, gangrene in leg, skin, lung, bladder, liver, and renal cancer (3). Arsenic in a case of familial poisoning (4) has been also reported. Mercury is very useful to monitor food methylmercury exposure caused by gold extraction in many polluted areas of the world, as in South America or China (5) because there is a linear relationship between blood and hair mercury content after methylmercury exposure (6). According to the World Health Organization, hair mercury content is 250 times higher than blood (7). Hair analysis has been applied to thallium poisoning in a group assassination attempt (8). Hair may also reflect food or water exposure to various elements (3) even in overlooked diagnosis or rare intoxication (3). We reported, for the first time, the interest in hair gadolinium content in a case of nephrogenic systemic nephrosis that was due to gadolinium salts magnetic resonance imaging (9). Moreover, hair analysis by inductively coupled plasma mass spectrometry (ICP-MS) is useful because it is multielementary (10). Furthermore, systems coupling liquid chromatography (LC) and ICP-MS are currently available to perform element speciation (11). Collection of both hair and nails is noninvasive, only a small sample size is required for analysis and allows for easy long-term storage. However, nails have attractive advantages over hair. If nail and hair are rich in fibrous proteins (i.e., alpha-keratins that contain abundant cysteine residues, up to

Reproduction (photocopying) of editorial content of this journal is prohibited without publisher’s permission.


22% in nail and approximately 12% in hair, due to disulfide groups), the nail will trap more elements such as arsenic or mercury. The presence of external contamination is less likely, particularly for toenails, especially to monitor metal workplace exposure and growth rates that are less variable than hair. Furthermore, hair analysis can be altered by cosmetic procedures such as dyeing, bleaching, and permanent waving, which is known to decrease xenobiotic content in hair. The nail plate is formed by layers of keratinized cells produced by the nail matrix, a highly proliferative epidermal tissue (2). Like the stratum corneum, the cytoplasmic keratin mass is partially crystalline and partially amorphous. The nail plate overlays the nail bed, a non-cornified tissue; at the interface, nail bed cells are carried distally by the nail plate during the growth towards the free margin (2). The keratinization of the nail plate in the matrix occurs both on the dorsal and the ventral side of the forming nail plate. Most of the fibers of keratin are perpendicularly orientated to the axis of growth, but others are orientated in the outermost segment contributing to the fusing of the layers (2). The structure is so tightly knit that there is no cell exfoliation. Nail grows in two different directions, length and thickness (2). The proliferation of the matrix involves a distal growth of nail at the rate of about 0.1 mm/day for fingernails (12,13) and a rate of about 0.03 to 0.04 mm/day for toenails (13). Growth slows down with increasing age, but also due to other factors like cold climatic conditions, and under other conditions like disease, malnutrition (2). Growth is faster in nail-biters, but it is the same for men and women. The second direction is growth due to the increase of the nail caused by production of ventral layers in the nail bed during progression from the luna to the free margin (14). This thickening rate is constant and slow, with a mean value of 0.027 mm/mm length (15). The mechanism of xenobiotic incorporation into nails includes incorporation into the matrix by the formation of keratinized tissue, via blood flow during linear growth; incorporation via nail bed, during thickening growth; and possible environmental contamination that may provide rapid access of xenobiotics to the distal nail. Because of the main mechanism of xenobiotics incorporation during linear growth, their presence in nail clippings would suggest an administration occurring over 3–5 months for fingernails and even longer for toenails.

standard solutions (30 elements) were from Merck (Darmstadt, Germany). Other elements (W, Pd, Pt, Sn, Ge, Hg, Sb, La, Gd), the rhodium and the indium internal standard solutions were obtained from CPI International (Amsterdam, Holland). As there was a lack of certified reference material, adequate quality assessment scheme was ensured by an interlaboratory nail testing organized by the Institut National de Santé Publique du Quebec, Sainte Foy, Canada. Sample preparation

Fingernail specimens were obtained from both sexes, 130 healthy volunteers, with no previous medical treatment or supposed occupational exposure. Thirty-two elements were assessed: Li, Be, B, Al, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Mo, Pd, Ag, Cd, Sn, Sb, Te, Ba, W, Pt, Hg, Tl, Pb, Bi, and U. Fingernail and toenail were collected as the same way from 50 other volunteers. Two new elements were added to the 32 elements (Gd, La). The impact of nail varnish was assessed among 10 women who regularly applying this cosmetic product; semiquantitative determinations of Ti, Fe, and Ce were added for these fingernails. After warm water and acetone Table I. Nail Analytical Validation Correlation Coefficient Element (r) 7Li 9Be 11B 27Al 51V 53Cr 55Mn 59Co 60Ni 65Cu 66Zn 69Ga 74Ge 75As 82Se 85Rb 88Sr 98Mo 105Pd

Materials and Methods

107Ag 111Cd 118Sn

A Thermo Elemental X7CCT benchtop series with PlasmaLab® software and without a dynamic reaction cell (Thermo Optek, Courtaboeuf, France) was used for multielementary determinations. Reagents

Plasma torch argon purity was higher than 99.999% (Linde Gas, Gargenville, France). Water was purified with a MilliQPLUS 185 system (Millipore, St. Quentin-en-Yvelines, France). Suprapur® nitric acid 65%, triton X100 and multi-element

121Sb 125Te 137Ba 182W 195Pt 202Hg 203Tl 208Pb 209Bi 238U

0.9999 0.9998 0.9991 0.9993 0.9998 0.9999 0.9996 0.9998 0.9998 0.9999 0.9996 0.9998 0.9999 0.9997 0.9997 0.9995 0.9995 0.9998 0.9995 0.9998 0.9998 0.9998 0.9998 0.9997 0.9998 0.9998 0.9999 0.9986 0.9995 0.9997 0.9997 0.9998

Limit of Detection (µg/g) 0.002 0.002 0.14 0.02 0.001 0.06 0.001 0.0003 0.01 0.01 0.01 0.0003 0.001 0.01 0.02 0.0003 0.0002 0.0004 0.001 0.0005 0.0003 0.001 0.0003 0.0006 0.001 0.0002 0.0001 0.004 0.00005 0.0003 0.00008 0.00004

Limit of Quantification (µg/g) 0.007 0.007 0.46 0.08 0.003 0.20 0.004 0.001 0.05 0.03 0.04 0.0009 0.002 0.02 0.06 0.001 0.0007 0.001 0.003 0.002 0.0009 0.002 0.001 0.002 0.003 0.001 0.0002 0.013 0.0002 0.001 0.003 0.0002

Intraassay CV %

Interassay CV %

6.5 3.9 3.6 2.3 1.7 3.5 1.7 2.3 1.8 1.3 1.1 2.2 1.8 3.5 2.6 2.0 1.0 3.9 2.9 0.7 0.7 1.0 1.0 6.7 0.8 2.1 1.5 0.4 3.7 0.7 1.4 2.0

6.1 8.8 8.9 7.7 9.0 9.3 6.6 7.9 6.4 10.4 8.1 8.9 7.6 6.4 7.8 5.8 7.0 8.2 22.3 9.9 5.9 5.9 5.2 6.1 5.5 7.2 6.2 9.5 4.7 4.4 5.3 7.2

93


decontamination, 20 mg of nail were digested with 20 µL pure nitric acid, 1 h at 70°C. Then, after cooling 100 µL of the solution was diluted with 100 µL nitric acid 2% and 3800 µL solution (nitric acid 1%, butanol 0.5%, triton 0.01%, In and Rh 1 ppb). Twenty-three elements were quantified in the same way as in the Canadian nail powder quality control: Ag, Al, As, Ba, Be, Cd, Co, Cr, Cu, Hg, Mn, Mo, N, Pb, Pt, Sb, Se, Sn, Te, Ti, U, V, and Zn. Among these elements, 14 were fortified.

Results Linearity measured as the correlation coefficient was higher than 0.99 for all elements (Table I). The limit of detection (LOD) ranged from 0.00004 µg/g (i.e., 40 pg/g or ppt) for U to 0.1 µg/g for B. The intra-assay and interassay inaccuracies Table II. Canadian Interlaboratory Control Nail Testing

Element

Number of Participants

Ag* Al As* Ba Be* Cd* Co* Cr Cu Hg* Mn Mo* Ni Pb Pt* Sb* Se Sn* Te* Tl* U* V* Zn

12 15 16 12 14 16 16 15 16 12 17 15 15 17 13 15 14 13 11 15 12 13 13

Mean of All Participants (µg/g)

Measured Concentration (µg/g)

Z Score

0.79 28.8 1.7 1.7 0.59 0.68 0.24 1.3 16.5 7.6 0.76 0.91 2.8 6.2 0.43 1.9 1.3 5.4 1.5 0.35 1.1 0.70 147

0.0 0.0 0.4 –0.7 0.7 0.0 –0.2 –1.4 –0.8 –1.9 –1.1 –0.2 1.0 –2.4 0.0 0.8 0.5 –1.3 –0.2 –0.1 0.0 –0.4 –0.5

0.79 28.8 1.6 1.9 0.53 0.68 0.26 1.7 17.4 8.7 0.92 0.95 2.5 7.3 0.43 1.7 1.2 5.9 1.5 0.36 1.1 0.76 153

* Fortified element.

Table III. Performance Criteria, Assigned Values, and Z Scores

94

Concentration Range (µg/g)

Maximum Accepted Error

< 0.5 0.5–2 2–5 >5

100% 50% 30% 20%

Assigned Deviation 33.3% 16.7% 10.0% 6.7%

measured as the variation coefficient were below 5% and 10%, respectively, except for Pd interassay inaccuracy, which was 22.3%. Results obtained with the Canadian nail quality control are reported (Table II). The table shows the results, the target expressed as the median value of all participants and the zscore. A preliminary calculation of the median and standard deviation was performed. Results outside the range of three standard deviations from the median were excluded from further calculations. Performance criteria are reported in Table III. Performance was rated using z-score. The z-score was defined as follows: z=

result – assigned value assigned deviation

In the absence of an assigned value obtained from this regular interlaboratory comparison program, the median is used as the assigned value. Interpretation of z-scores: [z-score = 2] was satisfactory; 2 < [z-score] < 3 was questionable; and [z-score] = 3 was unsatisfactory. Table IV. Proposed Reference Ranges Derived from Concentrations Found in Fingernail Samples from 130 Healthy Volunteers

Lithium Beryllium Boron Aluminum Vanadium Chromium Manganese Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Rubidium Strontium Molybdenum Palladium Silver Cadmium Tin Antimony Tellurium Barium Tungsten Platinum Mercury Thallium Lead Bismuth Uranium

Median (µg/g)

Reference Range 5th–95th Percentile (µg/g)

0.021 0.004 0.43 19.5 0.051 0.38 0.32 0.020 0.94 6.1 108 0.035 0.004 0.031 0.62 0.23 0.61 0.012 0.015 0.10 0.028 0.22 0.039 0.0003 0.66 0.003 0.0001 0.29 0.0004 0.52 0.011 0.003

0.006–0.087 0.001–0.011 0.07–3.14 4.00–76.2 0.027–0.114 0.03–1.89 0.10–1.48 0.009–0.069 0.22–8.34 3.9–12.4 72–182 0.012–0.142 0.002–0.007 0.005–0.086 0.44–0.91 0.06–0.69 0.28–1.64 0.005–0.034 0.006–0.048 0.01–0.60 0.009–0.196 0.05–0.90 0.012–0.196 0.0003–0.0009 0.21–3.07 0.001–0.027 0.00005–0.0013 0.06–0.83 0.0002–0.0012 0.10–3.71 0.001–0.26 0.001–0.01


One hundred and thirty volunteers’ fingernail reference ranges were proposed for the 32 elements (Table IV). Fifty fingernail and toenail reference ranges were proposed for 34 elements (Table V). The impact of varnish among 10 women regularly applying this cosmetic product is consistent with higher nail concentrations of Al, Ag, and Bi. Semiquantitative determination of Ti, Fe, and Ce also indicate elevated levels of these elements, as acetone or ethyl acetate seems to have no influence on nail metal content. Table VI presents six cases of lead exposure in a family. The mother and the father had elevated whole blood and fingernails or hair lead during the exposure period. Whereas the two oldest children did not show very significant blood or nail lead increase, the two youngest had elevated or very elevated blood and nails (fingernails and toenails) lead levels. The last two cases are consistent with earlier lead exposure as suggested by nail con-

centration (fingernails and toenails), but blood was sampled too late. In all these cases, the lead origin was old painted doors that were thermically burned in ventilated spaces. The lead paint contents from these cases are reported (Table VII).

Discussion

Linearity was considered excellent as the correlation coefficient was higher than 0.99 for all elements. The LOD was particularly low for all elements ranging from 40 pg/g for U to 0.1 µg/g for Bi with a 20-mg fingernail sample which can be easily reduced to 10 mg. The results obtained from the Canadian powder nail interlaboratory exercise were very good. The zscores obtained for the 23 elements were below z.o, except one with a 2.4 z value. Reference 5th to 95th percentile ranges for the 130 healthy volunteers’ fingernails were quite similar for all elements, except for Table V. Proposed Reference Ranges Derived from Concentrations Found in Ga and Pd due to an analytical problem, reFingernail and Toenail Samples from 50 Healthy Volunteers spectively interference measure with Ba and Fingernails Toenails contamination with Pd used as matrix modifier for atomic absorption spectrometry near Reference Range Reference Range the ICP-MS apparatus. Median 5th–95th Percentile Median 5th–95th Percentile Statistical data of the multielement 130 and (µg/g) (µg/g) (µg/g) (µg/g) 50 nail determinations show log-normal disLithium 0.019 0.005–0.060 0.030 0.003–0.094 tribution with some values higher than the Beryllium 0.005 0.001–0.010 0.005 0.001–0.010 95th percentile. For this reason we preferred Boron 0.41 0.09–1.45 0.46 0.07–0.75 to express the target reference values as the Aluminum 14.9 4.9–36.6 10.7 2.3–30.9 median and not the mean, with the reference Vanadium 0.032 0.015–0.081 0.029 0.007–0.070 range from the 5th to the 95th percentile. Our Chromium 0.42 0.18–0.76 1.14 0.11–8.75 results are very similar for most elements to Manganese 0.36 0.14–1.67 0.36 0.12–2.08 those obtained by Rodushkin and Axelsson Cobalt 0.017 0.008–0.043 0.013 0.006–0.033 using a double focusing sector field ICP-MS for Nickel 0.91 0.29–2.84 0.38 0.08–1.27 nails in 96 inhabitants of Northern Sweden Copper 6.5 4.3–9.4 3.6 2.1–6.8 (16). For 12 elements French inhabitant nail Zinc 108 83–143 83 63–105 concentrations were lower (Li, V, Cr, Mn, As, Gallium 0.032 0.015–0.120 0.029 0.012–0.102 Germanium 0.004 0.003–0.010 0.003 0.002–0.008 Mo, Cd, Sn, W, Tl, Bi, U), and for 3 elements Arsenic 0.072 0.024–0.404 0.086 0.033–0.413 they were higher (Ga, Pd, Hg). Ga higher Selenium 0.74 0.47–1.06 0.68 0.37–0.88 values were probably due to analytical interRubidium 0.17 0.05–0.45 0.48 0.24–1.21 ference with Ba, as the double charge mass of Strontium 0.54 0.28–1.00 0.94 0.32–2.08 Ga was Ba. For Pd, contamination was due to Molybdenum 0.014 0.006–0.034 0.007 0.003–0.015 palladium chloride used as a matrix modifier Palladium 0.044 0.011–0.072 0.040 0.011–0.067 for GFSAA aluminum determination near ICPSilver 0.17 0.04–1.55 0.028 0.009–0.137 MS apparatus. Mercury difference may be exCadmium 0.031 0.011–0.137 0.011 0.003–0.042 plained by a seafood origin as Le Havre is near Tin 0.35 0.16–0.68 0.10 0.03–0.35 the sea. With 0.29 and 0.20 µg/g fingernail Antimony 0.028 0.014–0.086 0.026 0.009–0.083 mercury content, these results are very similar Tellurium 0.0003 0.0003–0.009 0.0003 0.0003–0.010 Barium 0.65 0.26–2.44 0.56 0.20–1.98 to those obtained by Morton and colleagues Lanthanum 0.033 0.004–0.17 0.022 0.003–0.11 (17) and Samanta et al. (18) with 0.24 and Gadolinium 0.002 0.0003–0.011 0.002 0.0001–0.007 0.39 µg/g, respectively. For these authors, hair Tungsten 0.002 0.001–0.005 0.001 0.001–0.003 mercury contents were 0.40 and 0.82 µg/g. On Platinum 0.0002 0.0001–0.0005 0.0001 0.0001–0.0002 the contrary, our fingernail arsenic concenMercury 0.20 0.09–0.56 0.16 0.07–0.38 trations (0.031 and 0.072 µg/g) were much Thallium 0.0003 0.0002–0.001 0.0005 0.0003–0.0009 lower than concentrations reported in the RoLead 0.72 0.22–3.82 0.46 0.07–1.80 dushkin and Axelsson study (16) (0.223 µg/g), Bismuth 0.011 0.003–0.130 0.004 0.001–0.035 probably due to different mineral arsenic inUranium 0.003 0.001–0.005 0.002 0.001–0.006 take, as seafood organic arsenic, is quickly

95


cleared from the body and is not incorporated into nail or hair. However, our results are very similar to those obtained in 329 subjects studied by Beane-Freeman et al. (0.040 µg/g) (19). The impact of varnish on nail metal concentration is consistent with elevations for Al, Ag, Bi, Ti, Fe, and Ce, in accordance with pigment salt content. It has been well known for a long time that some elements like arsenic are trapped in keratinized matrices (hair and nails). Nail metal and metalloid content is considered to reflect longterm exposure as this compartment remains isolated from other metabolic activities. Nail xenobiotic analysis offers advantages compared to hair, as it is less affected by exogenous contamination, it is not altered by cosmetic procedure (dyeing, bleaching, permanent waving) or by melanin as nail is melanin free. Many elements have been evaluated during occupational exposures; however, the interpretation remains controversial (3). Hair lead and cadmium environmental external contamination has been demonstrated by Anwar (20). These elements Table VI. Six Cases of Lead Exposure in a Family and Two Other Cases

Sex/Age F 43 years

Date 04.12.06 02.01.07 03.01.07 05.12.07

Fingernail N* < 3.7 µg/g

02.01.07 03.01.07

M 15 years 03.01.07 05.02.07 M 11 years 02.01.07 03.02.07 05.13.07 M 7 years

02.01.07 03.01.07 04.11.07 05.02.07

M 42 years 06.27.07

96

82

None

191

None

5.1 (toenail 4.5) 45.1 4.3

None 33 39

None

50

None

95 81

None

8.2 (toenail 6.4) 89.1 19.1 (toenail 19.2) 185

20.4 (toenail 46.8) 10.5 (toenail 10.2)

11.5 (toenail 13.3) 06.27.07 13.9 07.09.07

None

Table VII. Paint Lead Contents in the Two Family Cases 82

06.07.07

* Normal value.

Signs

226

07.09.07 F 34 years

Whole Blood Adult < 63 µg/L

33.8

M 41 years 05.15.06 04.12.07 F 17 years

Hair N< 4.6 µg/g

of hair content were higher than toenail content, reported in the inhabitants of an urban area, but it was the same in the inhabitants of a nonurban area. As toenail content is less affected by external contamination than fingernail, it is a better matrix to evaluate occupational exposure (21). Nail metal or metalloid ICP-MS has been assessed during various intoxications or exposure cases like arsenic and criminal poisonings (22), as the reconstitution of two cases of thallium poisoning in a group assassination attempt with 2.52 and 1.67 µg/g in fingernails, 1.46 and 1.27 µg/g in hair of the victims (8), but also to confirm lead in a fatal poisoning with 13.6 µg/g in nails and 30.2 µg/g in hair (23). Tungsten has been determined in nails and hair in a case of acute intoxication in humans (3.81 and 4.26 µg/g, respectively), by Marquet et al. (24). Fingernails have been proposed also as biological indices of metal exposure (25) and in various diseases (26,27). Many environmental exposures have been studied using fingernails, toenails or hair, especially arsenic, as well as mercury, and other metals (28–30). As regards mercury, amalgam mercury toxicity has been discussed. Joshi et al. (31) have determined that toenail mercury in dentists is higher (0.94 µg/g) compared to the general population (0.54 µg/g). Morton et al. (17) also found higher mercury content in dentists (fingernails, 1.42 µg/g; toenails, 0.43 µg/g) than in non dentists (fingernails, 0.24 µg/g; toenails, 0.18 µg/g). We have obtained very similar results with 50 healthy volunteers (fingernails, 0.20 µg/g; toenails, 0.16 µg/g). Arsenic mass poisoning in groundwater, particularly in Bangladesh, surpasses any incident previously observed. In West Bangladesh, more than 60% of the population lives in drinking water polluted areas. It is estimated that between 35 and 77 million are at risk of drinking contaminated water (32). Anawar et al. (33) analyzed water samples in 10 districts of Bangladesh: 51% on an average contained arsenic levels of 0.05 to 2.50 mg/L and 95% of nail, 96% of hair, and 94% of urine sample contained arsenic above a normal level (34). Fingernail concentrations ranged from 1.3 µg/g to 33.98 µg/g, compared to normal values ranging from 0.43 µg/g to 1.08 µg/g (35), which are rather high values in contrast with our French series (< 0.4 µg/g). Samanta et al. (18) studied arsenic and 9 other elements in fingernails of arsenic victims in West Bengal (Se, Hg, Zn, Pb, Ni, Cd, Mn, Cu, and Fe). This study revealed high amounts of arsenic (median 4.73 µg/g) and other elements, lead, nickel, manganese with respective median concentrations of 7.47, 2.98, and 24.51 µg/g, in fingernails. Validity of arsenic and selenium fingernail determination has been recently reviewed (36). Element speciation has also progressed using HPLC–ICP-

Paint Lead Content % (authorized < 0.5%)

None

25

Six cases in a family Two other cases

House doors: 26.0% House doors: 2.58% House shutters: 2.32%


MS. Mandal et al. (11) reported in a contaminated area that fingernails contained mainly arsenite iAs (III) and arsenate iAs (V) 58.6% and 21.5%, respectively, and monomethylarsinic acid MMA (V), dimethylarsinic acid DMA (III), dimethylarsinic acid DMA (V) 7.7%, 9.2%, 3.0%, respectively. Arsenic speciation in fingernails seems to be more correlated with arsenism than arsenic speciation in hair (11). Non toxic arsenic forms like arsenobetaine and arsenocholine that are in huge quantities in seafood are quickly cleared in urine and not fixed in hair or nails (37). Many studies have compared metal concentrations in hair and nails, fingernails or/and toenails from the same subjects (8,16–18,20,23–25,27,28,33). They concluded that nails, especially toenails are better biomarkers than hair to monitor metal overall exposure. In fact it is necessary to distinguish between metal external air exposure and respiratory or digestive absorption. For air exposure it is suggested that dust containing metals was attached to hair sample, particularly in a typical urban environment with a heavy traffic load, congested population and industrial activities (20). This external contamination cannot be totally removed by the decontamination procedure. In a recent paper, Ohno et al. (38) found a positive correlation in 59 women, free from mercury occupational exposure, between daily mercury intake and levels in hair, toenail, and urine (r = 0.55, 0.54, and 0.60, p < 0.001). In contrast, the concentration comparison between metal or metalloid hair and nail content was satisfactory as reported by many authors after digestive or respiratory absorption. In a very interesting paper, Rodushkin et al. (16) found that significant correlations exist between different elements in hair and nails, as well as between hair and nail concentrations for several elements. During arsenic poisoning in groundwater in Bangladesh, Anawar et al. (33) reported high arsenic level in both hair and nails ranging respectively from 1.1–19.8 µg/g to 1.3–34.0 µg/g. Karpas et al. (39) have studied hair and nails as indicators for ingestion of uranium in drinking water. They found a direct correlation between the estimated intake of uranium in drinking water and the concentration found in urine, hair and toenails. These authors have also measured the isotopic ratio 234U/238U in hair and toenail and found a very good correlation between hair and toenail (r = 0.98) (40).

Conclusions ICP-MS multielement determination in nails is a specific and a sensitive method. With only a limited sample, it allows to quantify more than 30 elements simultaneously within a rather short period of time. This method suits batch analysis very well. Sample collection is non-invasive and represents a good alternative to hair, particularly when people are bald or cannot be sampled for religious reasons. It is very useful to explore a great number of elements in various fields: clinical, forensic, or environmental toxicology but also workplace testing, during long-term metal exposure. Moreover, it is an ideal tool for epidemiological studies.

Acknowledgments The authors are grateful to Richard Medeiros, Rouen University Hospital Medical Editor, for his advice in editing the manuscript.

References 1. Analytical and Practical Aspects of Drug Testing in Hair, P. Kintz, Ed. CRC Press, Boca Raton, FL, 2006. 2. A. Palmieri, S. Pichini, R. Pacifici, P. Zuccaro, and A. Lopez. Drugs in nails: physiology, pharmacokinetics and forensic toxicology. Clin. Pharmacokinet. 38: 95–110 (2000). 3. J.-P. Goullé. Metals. In Analytical and Practical Aspects of Drug Testing in Hair, P. Kintz, Ed. CRC Press, Boca Raton, FL, 2006, pp 343–370. 4. J.-P. Goullé, L. Mahieu, and P. Kintz. The murder weapon was found in the hair! Ann. Toxicol. Anal. 17: 243–245 (2005) (in French). 5. M. Horvat, N. Nolde, V. Fajon, V. Jereb, M. Logar, S. Lojen, R. Jacimovic, I. Falnoga, Q. Liya, J. Faganeli, and D. Drobne. Total mercury, methylmercury and selenium in mercury polluted areas in the province Guizhou, China. Sci. Total Environ. 304: 231–256 (2003). 6. C. Johnsson, A. Schütz, and G. Sällsten. Impact of consumption of freshwater fish on mercury levels in hair, blood, urine, and alveolar air. J. Toxicol. Environ. Health A 68: 129–140 (2005). 7. Methylmercury. Environmental Health Criteria 101. World Health Organization, Geneva, Switzerland, 1990. 8. J. McCormack and W.Mc Kinney. Thallium poisoning in group assassination attempt. Postgrad. Med. 74: 239–241, 244 (1983). 9. E. Saussereau, C. Lacroix, A. Cattanéo, L. Mahieu, and J.-P. Goullé. IRM avec chélates de gadolinium et fibrose systémique néphrogénique: premier cas clinique décrit avec dosage du gadolinium par ICP-MS. Ann. Toxicol. Anal. 19: 227–232 (2007). 10. J.-P. Goullé, L. Mahieu, L. Bonneau, G. Lainé, D. Bouige, and C. Lacroix. Validation d’une technique de dosage multiélémentaire des métaux et métalloïdes dans les cheveux par ICP-MS. Valeurs de référence chez 45 témoins. Ann. Toxicol. Anal. 17: 97–102 (2005). 11. B.K. Mandal, Y. Ogra, and K.T. Suzuki. Speciation of arsenic in human nail and hair from arsenic-affected area by HPLC-inductively coupled argon plasma mass spectrometry. Toxicol. Appl. Pharmacol. 189: 73–83 (2003). 12. W.E. Le Gros Clark and L.H. Dudley Buxton. Studies in nail growth. Br. J. Dermatol. 50: 221–235 (1938). 13. W.B. Bean. A note on fingernail growth. J. Invest. Dermatol. 20: 27–31 (1953). 14. M. Johnson and S. Shuster. Ventral nail contribution to the nail plate is continuous along the length of the nail bed. Br. J. Dermatol. 123: 825 (1990). 15. M. Johnson and S. Shuster. Continuous formation of nail along the bed. Br. J. Dermatol. 128: 277–280 (1993). 16. I. Rodushkin and M.D. Axelsson. Application of double focusing sector field ICP-MS for multielemental characterization of human hair and nails. Part II. A study of the inhabitants of northern Sweden. Sci. Total Environ. 262: 21–36 (2000). 17. J. Morton, H.J. Mason, K.A. Ritchie, and M. White. Comparison of hair, nails and urine for biological monitoring of low level inorganic mercury exposure in dental workers. Biomarkers 9: 47–55 (2004). 18. G. Samanta, R. Sharma, T. Roychowdhury, and D. Chakraborti. Arsenic and other element in hair, nails and skin-scales of arsenic victims in West Bengal, India. Sci. Total Environ. 326: 33–47 (2004).

97


19. L.E. Beane-Freeman, L.K. Denis, C.F. Lynch, P.S. Thorne, and C.L. Just. Total arsenic content and cutaneous melanoma in Iowa. Am. J. Epidemiol. 160: 679–687 (2004). 20. M. Anwar. Arsenic, cadmium and lead levels in hair and toenail samples in Pakistan. Environ. Sci. 12: 71–86 (2005). 21. F. Barbosa, Jr., J.E. Tanus-Santos, R.F. Gerlach, and P.J. Parsons. A critical review of biomarkers used for monitoring human exposure to lead: advantages, limitations, and future needs. Environ. Health Perspect. 12: 1669–1674 (2005). 22. C.R. Daniel, III, B.M. Piraccini, and A. Tosti. The nail and hair in forensic science. J. Am. Acad. Dermatol. 50: 258–261 (2004). 23. T. Lech. Exhumation examination to confirm suspicion of fatal lead poisoning. Forensic Sci. Int. 158: 219–223 (2006). 24. P. Marquet, B. François, H. Lotfi, A. Turcant, J. Debord, G. Nedelec, and G. Lachâtre. Tungsten determination in biological fluids, hair and nails by plasma emission spectrometry in a case of severe acute intoxication in man. J. Forensic Sci. 42: 527–530 (1997). 25. R. Mehra and M. Juneja. Fingernails as biological indices of metal exposure. J. Biosci. 30: 253–257 (2005). 26. S. Rajpathak, E.B. Rimm, T. Li, J.S. Morris, M.J. Stampfer, W.C. Willett, and F.B. Hu. Lower toenail chromium in men with diabetes and cardiovascular disease compared with healthy men. Diabetes Care 27: 2211–2216 (2004). 27. Y.R. Tang, S.Q. Zhang, Y. Xiong, Y. Zhao, H. Fu, H.P. Zhang, and K.M. Xiong. Studies of five microelement contents in human serum, hair, and fingernails correlated with aged hypertension and coronary heart disease. Biol. Trace Elem. Res. 92: 97–104 (2003). 28. B. Nowak and J. Chmielnicka. Relationship of lead and cadmium to essential elements in hair, teeth, and nails of environmentally exposed people. Ecotoxicol. Environ. Saf. 46: 265–274 (2000). 29. M.J. Slotnick, J.R. Meliker, G.A. AvRuskin, D. Ghosh, and J.O. Nriagu. Toenails as a biomarker of inorganic arsenic intake from drinking water and foods. J. Toxicol. Environ. Health A 70: 148–158 (2007). 30. J.B. Wickre, C.L. Folt, S. Sturup, and M.R. Karagas. Environmental exposure and fingernail analysis of arsenic and mercury in children and adults in a Nicaraguan gold mining community. Arch. Environ. Health 59: 400–409 (2004).

98

31. A. Joshi, C.W. Douglass, H.D. Kim, K.J. Joshipura, M.C. Park, E.B. Rimm, M.J. Carino, R.I. Garcia, J.S. Morris, and W.C. Willett. The relationship between amalgam restorations and mercury levels in male dentists and nondental health professionals. J. Public Health Dent. 63: 52–60 (2003). 32. A.H. Smith, E.O. Lingas, and M. Rahman. Contamination of drinking-water by arsenic in Bangladesh: a public health emergency. Bull. World Health Organ. 78: 1093–1103 (2000). 33. H.M. Anawar, J. Akai, K.M.G. Mostofa, S. Safiullah, and S.M. Tareq. Arsenic poisoning in groundwater: health risk and geochemical sources in Bangladesh. Environ. Int. 27: 597–604 (2002). 34. DHC report. The Arsenic Disaster and Dhaka Community Hospital, at the seminar on arsenic disaster in Bangladesh environment, Dhaka, Bangladesh. 1997; January 6. 35. R.K. Dhar, B.K. Biswas, G. Samanta, B.K. Mandal, D. Chakraborty, S. Roy, A. Jafar, A. Islam, G. Ara, S. Kabir, A.W. Khan, S.A. Ahmen, and S.A. Hadi. Groundwater arsenic calamity in Bangladesh. Curr. Sci. 73: 48–59 (1997). 36. M.J. Slotnick and J.O. Nriagu. Validity of human nails as a biomarker of arsenic and selenium exposure: a review. Environ. Res. 102: 125–135 (2006). 37. National Research Council’s Subcommittee on Arsenic in Drinking Water, Arsenic In Drinking Water. National Academy Press, Washington, D.C., 1999, pp 177–192. 38. T. Ohno, M. Sakamoto, T. Kurosawa, M. Dakeishi, T. Iwata, and K. Murata. Total mercury levels in hair, toenail, and urine among women free from occupational exposure and their relations to renal tubular function. Environ. Res. 103: 191–197 (2007). 39. Z. Karpas, O. Paz-Tal, A. Lorber, L. Salonen, H. Komulainen, A. Auvinen, H. Saha, and P. Kurttio. Urine, hair, and nails as indicators for ingestion of uranium in drinking water. Health Phys. 88: 229–242 (2005). 40. Z. Karpas, A. Lorber, H. Sela, O. Paz-Tal, Y. Hagag, and P. Kurttio. Measurement of the 234U/238U ratio by MC-ICPMS in drinking water, hair, nails, and urine as an indicator of uranium exposure source. Health Phys. 89: 315–321 (2005). Manuscript received April 1, 2008; revision received April 28, 2008.