- Email: [email protected]
Mercury in saliva and scalp hair from dental amalgam
Journal of Hazardous Materials 179 (2010) 1166–1167
Contents lists available at ScienceDirect
Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat
Letter to the Editor
Mercury in saliva and scalp hair from dental amalgam To the Editor: We have one comment about the interesting report by Fakour et al. [1] on the estimation of mercury in saliva as well as scalp hair samples among Iranian women exposed to mercury-containing dental amalgam. They conclude that “mercury can be absorbed systematically upon swallowing and to be concentrated in different body tissues such as hair” [1]. Although mercury-containing dental amalgam is truly the most important source of vapor and inorganic mercury in the general population [2], it is possible that mercury forms (species) in oral cavity are not only inorganic, as the article by Leistevuo et al. cited by the authors points out [3]. Having shown that both methyl and ethyl mercury are present in saliva samples of mercury amalgam bearers, [4–6] it is now essential to determine whether organic mercury generated from dental amalgam may contribute to the levels of hair mercury in individuals who are exposed to mercury amalgam fillings, as seen in Fakour et al.’s work [1]. Organic mercury is formed in saliva owing to the presence of dental amalgams. A plausible biochemical explanation would involve mercury vapor (Hg0 ) emitted from amalgams which is reduced to mercuric mercury (Hg2 + ) and then transformed in mono-methylmercury (CH3 Hg+ ) [3] and ethyl mercury (CH3 CH2 Hg+ ) by oral bacteria [4,6]. It is also well-known that the organic form of mercury is absorbed at about 90% in the intestinal compartment from food (as compared with an average of inorganic form of 7% in humans). Therefore, it appears highly likely and consistent that organic mercury generated into the oral cavity owing to mercury amalgam may accumulate in growing scalp hair. Both methyl mercury and ethyl mercury may be taken up into hair [7,8]. Because it is very difficult to measure and differentiate between organic and inorganic mercury accumulated into scalp hair from hair sample of the same donor, it seems reasonable to assume that mercury organic compounds derived from oral cavity – in persons with exposure to amalgams – may be a major potential confounder of the relation between mercury amalgam fillings and the concentrations of mercury in hair. In support to this, organic mercury has a greater selective uptake into human scalp hair with respect to inorganic mercury [7–11]. Also, it is important for readers to remember that the present work by Fakour and colleagues is in accordance with previous studies that have demonstrated an association between the number of mercury dental tooth fillings and the mean concentration of total mercury in human scalp hair [12,13]. Perhaps more importantly, in a cross-sectional study on mercury analysis in mother–newborn pairs, it has been found that
0304-3894/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2010.03.065
elevated levels of total mercury in both maternal and fetal scalp hair were associated with mercury-containing amalgam restorations [14]. The paper by Fakour et al. shows that the total mercury levels in scalp hair among Iranian women is possibly influenced by the number of mercury-containing amalgam fillings and it stimulates thus discussion and debate about the necessity of integrated assessments analyses on mercury amalgam exposure by using saliva as a matrix for biological monitoring. References [1] H. Fakour, A. Esmaili-Sari, F. Zayeri, Scalp hair and saliva as biomarkers in determination of mercury levels in Iranian women: amalgam as a determinant of exposure, J. Hazard. Mater. 4 (December) (2009) 1. [2] L.F. Lorscheider, M.J. Vimy, A.O. Summers, Mercury exposure from “silver” tooth fillings: emerging evidence questions a traditional dental paradigm, FASEB J. 9 (1995) 504–505, 2. [3] J. Leistevuo, T. Leistevuo, H. Helenius, L. Pyy, M. Osterblad, P. Huovinen, J. Tenovuo, Dental amalgam fillings and the amount of organic mercury in human saliva, Caries Res. 35 (2001) 163–166, 3. [4] P.D. Pigatto, G. Guzzi, G. Severi, Oral lichen planus: mercury and its kin, Arch. Dermatol. 141 (2005) 1472–1473, 4. [5] G. Guzzi, C. Minoia, P.D. Pigatto, G. Severi, Methylmercury, amalgams, and children’s health, Environ. Health Perspect. (2006) 114–149, 5. [6] D. Gibicar, M. Logar, M. Horvat, A. Marn-Pernat, R. Ponikvar, M. Horvat, Simultaneous determination of trace levels of ethylmercury and methylmercury in biological samples and vaccines using sodium tetra(n-propyl)borate as derivatizing agent, Anal. Bioanal. Chem. 388 (2007) 329–340, 6. [7] E. Cernichiari, G.J. Myers, N. Ballatori, G. Zareba, J. Vyas, T. Clarkson, The biological monitoring of prenatal exposure to methylmercury, Neurotoxicology 28 (2007) 1015–1022. [8] G. Zareba, E. Cernichiari, L.A. Goldsmith, T.W. Clarkson, Validity of methyl mercury hair analysis: mercury monitoring in human scalp/nude mouse model, J. Appl. Toxicol. 28 (2008) 535–542, 8. [9] T. Giovanoli-Jakubczak, M.R. Greenwood, J.C. Smith, T.W. Clarkson, Determination of total and inorganic mercury in hair by flameless atomic absorption, and of methylmercury by gas chromatography, Clin. Chem. 20 (1974) 222–229. [10] M. Berglund, B. Lind, K.A. Björnberg, B. Palm, O. Einarsson, M. Vahter, Interindividual variations of human mercury exposure biomarkers: a cross-sectional assessment, Environ. Health. 3 (2005), 4:20. [11] L. Magos, T.W. Clarkson, The assessment of the contribution of hair to methyl mercury excretion, Toxicol. Lett. 182 (November 1–3) (2008) 48–49. [12] S.R. Maloney, C.A. Phillips, A. Mills, Mercury in the hair of crematoria workers, Lancet 352 (1998) 1602. [13] J.B. Nielsen, P. Grandjean, Mercury in hair – but from where? Lancet 353 (1999) 502. [14] S.W. Lindow, R. Knight, J. Batty, S.J. Haswell, Maternal and neonatal hair mercury concentrations: the effect of dental amalgam, BJOG 110 (2003) 287–291.
Paolo D. Pigatto Department of Technology for Health, Dermatological Clinic, IRCCS Galeazzi Hospital, University of Milan, Milan, Italy
Letter to the Editor / Journal of Hazardous Materials 179 (2010) 1166–1167
Claudio Minoia Anna Ronchi Laboratory of Environmental and Toxicology Testing “S. Maugeri” - IRCCS, Pavia, Italy Gianpaolo Guzzi ∗ Italian Association for Metals and Biocompatibility Research, A.I.R.M.E.B., (not-for-profit organization), Via A. Banfi, 4, 20122 Milan, Italy
1167
∗ Corresponding
author. Tel.: +39 02 782 561; fax: +39 02 919 758 53. E-mail address: gianpaolo [email protected] (G. Guzzi) 23 February 2010 Available online 31 March 2010
Contents lists available at ScienceDirect
Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat
Letter to the Editor
Mercury in saliva and scalp hair from dental amalgam To the Editor: We have one comment about the interesting report by Fakour et al. [1] on the estimation of mercury in saliva as well as scalp hair samples among Iranian women exposed to mercury-containing dental amalgam. They conclude that “mercury can be absorbed systematically upon swallowing and to be concentrated in different body tissues such as hair” [1]. Although mercury-containing dental amalgam is truly the most important source of vapor and inorganic mercury in the general population [2], it is possible that mercury forms (species) in oral cavity are not only inorganic, as the article by Leistevuo et al. cited by the authors points out [3]. Having shown that both methyl and ethyl mercury are present in saliva samples of mercury amalgam bearers, [4–6] it is now essential to determine whether organic mercury generated from dental amalgam may contribute to the levels of hair mercury in individuals who are exposed to mercury amalgam fillings, as seen in Fakour et al.’s work [1]. Organic mercury is formed in saliva owing to the presence of dental amalgams. A plausible biochemical explanation would involve mercury vapor (Hg0 ) emitted from amalgams which is reduced to mercuric mercury (Hg2 + ) and then transformed in mono-methylmercury (CH3 Hg+ ) [3] and ethyl mercury (CH3 CH2 Hg+ ) by oral bacteria [4,6]. It is also well-known that the organic form of mercury is absorbed at about 90% in the intestinal compartment from food (as compared with an average of inorganic form of 7% in humans). Therefore, it appears highly likely and consistent that organic mercury generated into the oral cavity owing to mercury amalgam may accumulate in growing scalp hair. Both methyl mercury and ethyl mercury may be taken up into hair [7,8]. Because it is very difficult to measure and differentiate between organic and inorganic mercury accumulated into scalp hair from hair sample of the same donor, it seems reasonable to assume that mercury organic compounds derived from oral cavity – in persons with exposure to amalgams – may be a major potential confounder of the relation between mercury amalgam fillings and the concentrations of mercury in hair. In support to this, organic mercury has a greater selective uptake into human scalp hair with respect to inorganic mercury [7–11]. Also, it is important for readers to remember that the present work by Fakour and colleagues is in accordance with previous studies that have demonstrated an association between the number of mercury dental tooth fillings and the mean concentration of total mercury in human scalp hair [12,13]. Perhaps more importantly, in a cross-sectional study on mercury analysis in mother–newborn pairs, it has been found that
0304-3894/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2010.03.065
elevated levels of total mercury in both maternal and fetal scalp hair were associated with mercury-containing amalgam restorations [14]. The paper by Fakour et al. shows that the total mercury levels in scalp hair among Iranian women is possibly influenced by the number of mercury-containing amalgam fillings and it stimulates thus discussion and debate about the necessity of integrated assessments analyses on mercury amalgam exposure by using saliva as a matrix for biological monitoring. References [1] H. Fakour, A. Esmaili-Sari, F. Zayeri, Scalp hair and saliva as biomarkers in determination of mercury levels in Iranian women: amalgam as a determinant of exposure, J. Hazard. Mater. 4 (December) (2009) 1. [2] L.F. Lorscheider, M.J. Vimy, A.O. Summers, Mercury exposure from “silver” tooth fillings: emerging evidence questions a traditional dental paradigm, FASEB J. 9 (1995) 504–505, 2. [3] J. Leistevuo, T. Leistevuo, H. Helenius, L. Pyy, M. Osterblad, P. Huovinen, J. Tenovuo, Dental amalgam fillings and the amount of organic mercury in human saliva, Caries Res. 35 (2001) 163–166, 3. [4] P.D. Pigatto, G. Guzzi, G. Severi, Oral lichen planus: mercury and its kin, Arch. Dermatol. 141 (2005) 1472–1473, 4. [5] G. Guzzi, C. Minoia, P.D. Pigatto, G. Severi, Methylmercury, amalgams, and children’s health, Environ. Health Perspect. (2006) 114–149, 5. [6] D. Gibicar, M. Logar, M. Horvat, A. Marn-Pernat, R. Ponikvar, M. Horvat, Simultaneous determination of trace levels of ethylmercury and methylmercury in biological samples and vaccines using sodium tetra(n-propyl)borate as derivatizing agent, Anal. Bioanal. Chem. 388 (2007) 329–340, 6. [7] E. Cernichiari, G.J. Myers, N. Ballatori, G. Zareba, J. Vyas, T. Clarkson, The biological monitoring of prenatal exposure to methylmercury, Neurotoxicology 28 (2007) 1015–1022. [8] G. Zareba, E. Cernichiari, L.A. Goldsmith, T.W. Clarkson, Validity of methyl mercury hair analysis: mercury monitoring in human scalp/nude mouse model, J. Appl. Toxicol. 28 (2008) 535–542, 8. [9] T. Giovanoli-Jakubczak, M.R. Greenwood, J.C. Smith, T.W. Clarkson, Determination of total and inorganic mercury in hair by flameless atomic absorption, and of methylmercury by gas chromatography, Clin. Chem. 20 (1974) 222–229. [10] M. Berglund, B. Lind, K.A. Björnberg, B. Palm, O. Einarsson, M. Vahter, Interindividual variations of human mercury exposure biomarkers: a cross-sectional assessment, Environ. Health. 3 (2005), 4:20. [11] L. Magos, T.W. Clarkson, The assessment of the contribution of hair to methyl mercury excretion, Toxicol. Lett. 182 (November 1–3) (2008) 48–49. [12] S.R. Maloney, C.A. Phillips, A. Mills, Mercury in the hair of crematoria workers, Lancet 352 (1998) 1602. [13] J.B. Nielsen, P. Grandjean, Mercury in hair – but from where? Lancet 353 (1999) 502. [14] S.W. Lindow, R. Knight, J. Batty, S.J. Haswell, Maternal and neonatal hair mercury concentrations: the effect of dental amalgam, BJOG 110 (2003) 287–291.
Paolo D. Pigatto Department of Technology for Health, Dermatological Clinic, IRCCS Galeazzi Hospital, University of Milan, Milan, Italy
Letter to the Editor / Journal of Hazardous Materials 179 (2010) 1166–1167
Claudio Minoia Anna Ronchi Laboratory of Environmental and Toxicology Testing “S. Maugeri” - IRCCS, Pavia, Italy Gianpaolo Guzzi ∗ Italian Association for Metals and Biocompatibility Research, A.I.R.M.E.B., (not-for-profit organization), Via A. Banfi, 4, 20122 Milan, Italy
1167
∗ Corresponding
author. Tel.: +39 02 782 561; fax: +39 02 919 758 53. E-mail address: gianpaolo [email protected] (G. Guzzi) 23 February 2010 Available online 31 March 2010