Tooth lead

NC (chronic) (general population) Other Growth retardation in children 230-60 tooth lead >18.7 pg/g Angle and Kuntzelman 1989 Lauwers et al. 1986 Lyngbye et al. 1987 Huseman et al. 1992... 

Other investigators have also found that parameters of neurobehavioral function are associated with tooth lead levels. A cross-sectional cohort of school children in first grade was ascertained in the city of Aarhus, Denmark (Hansen et al. 1989), where the population is very homogeneous with regard to ethnicity and language. A total of 2,412 children were contacted and asked to contribute a shed deciduous tooth. A total of 1,291 children responded (response rate = 54%). Lead was determined in the... 

An analysis of eight cross-sectional and/or prospective studies which reported tooth lead and PbB levels of the same children found considerable consistency among the studies (Rabinowitz 1995). The mean tooth lead levels ranged from under 3 to over 12 pg/g. In a study of 63 subjects, dentin lead was found to be predictive of concentrations of lead in the tibia, patella, and mean bone lead 13 years after tooth lead assessment in half of them (Kim et al. 1996b). The authors estimated that a 10 pg/g increase in dentin lead levels in childhood was predictive of a 1 pg/g increase in tibia lead levels, a 5 pg/g in patella lead levels and a 3 pg/g increase in mean bone lead among the young adults. 

McMichael AJ, Baghurst PA, Vimpani GV, et al. 1994. Tooth lead levels and IQ in school-age children The Port Pirie cohort study. Am J Epidemiol 140 489-499. 

Rabinowitz MB, Leviton A, Bellinger D. 1989. Blood lead-tooth lead relationship among Boston children. Bull Environ Contam Toxicol 43 485-492. 

Pericoronitis- It is the inflammation of soft tissues surrounding the crown of a partially erupted tooth and most commonly, a wisdom tooth. It generally occurs when bacterial plaque and food debris accumulate beneath the flap of gum covering the partially erupted tooth. It is characterized by inflammation, often complicated by trauma from the opposing tooth, leads to swelling of the flap, tenderness, pain and a bad taste due to pus oozing from beneath the flap. 

Figure 6.2 Distribution of negative ratings by teachers on nine classroom behaviors in relation to tooth lead concentrations. [Replotted from H.L. Needleman et al., New England Journal of Medicine, 300, 689-695 (1979).]...

Winneke G, Hrdina K-G, Brockhaus A Neuropsychological studies in children with elevated tooth-lead concentrations, I pilot study. Int Arch Occup Environ Health 51 169-183, 1982... 

Stack, M.V. and Delves, H.T. (1982) Tooth-lead analysis - an interlaboratojv survey. In Egan, H. and West, T.S. (Eds.) lUPAC Collaborative Interlaboratory Studies in Chemical Analysis, Pergamon Press, Qxford, p. 115. 

In performing tooth lead analysis, it has to be considered that the lead concentrations vary among different tooth types (when analyzing whole teeth) as well as, within one tooth, between different tooth tissues (Ewers et al., 1990 Grandjean et al., 1984, 1986). In deciduous teeth the lead concentration tends to decrease from the medial incisors to the premolars. Whether there is a similar variation in permanent teeth of adults has not yet been evaluated. Thus, when comparing analytical data on lead concentrations in whole teeth, it should be stated what type of tooth was analyzed. 

The analytical techniques used for tooth lead analyses include MS, ASV, and X-ray fluorescence analysis. The X-ray fluorescence technique allows the measurement tooth of lead levels in situ (Shapiro et al., 1978). MS and ASV determinations require the tooth to be dissolved in nitrous acid prior to analysis. 

Due to these analytical difficulties Is appears that, particularly in the past, many tooth lead measurements have been performed unsatisfactorily. An interlaboratory comparison program on tooth lead analysis, organized by a lUPAC subcommittee, showed large interlaboratory variations (Stack and Delves, 1982) and in recent years the need for strict quality control has been emphasized repeatedly. 

The introduction of pyrolytically coated graphite tubes and the L vov platform technique in GF-AAS as well as of the Zeeman-GF-AAS technique offer improved possibilities to reduce matrix effects when measuring tooth lead in aqueous solutions. Where these techniques are available calibration with lead-spiked tooth solutions can be applied. Otherwise the analyses must be carried out by means of internal standard addition. The accuracy of the analytical procedure should be assessed by interlaboratory comparison, since, at present, no reference material of human teeth is available. 

The procedure subsequently described has been shown to provide accurate and precise analytical data in routine tooth lead analyses in the authors laboratory. Pretreatment of teeth ... 

A calibration graph is constructed from lead-spiked tooth solutions. The lower detection limit of the method Is 0.5 mg Pb/kg tooth. The precision expressed as relative standard deviation was found to be 3.2% at a tooth lead concentration of 6.83 mg Pb/kg tooth. 

Delves, H.T., Clayton. B.E., Carmichael, A.. Bubear, M. and Smith. M. (1982). An appraisal of the analytical significance of tooth lead measurements as possible indices of environmental exposure of children to lead. Ann. Clin. Biochem., 12.329-337. 

Mackie, A.C., Stephens, R., Townshend, A. and Waldron, H.A. (1977). Tooth lead levels in Birmingham children. Arch. Environ. Health, 32,178-185. 

Shapiro, I.M., Burke, A., Mitchell, G. and Bloch, P. (1978). X-ray fluorescence analysis of lead in teeth of urban children in situ Correlation between the tooth lead level and the concentration of blood lead and free erythroporphyrins. Environ. Res., 17. 46-52. 

Tooth decay (dental caries) is one of the most common diseases in humans [8]. It has been defined as a chronic, dietomiaobial, site-specific disease caused by a shift from protective factors favouring tooth remineralization to destructive factors leading to demineralization [9]. The specific factors leading to destruction of the mineral phase of the tooth are the presence of oral bacteria, mainly Streptococcus mutans [10], and the availability of fermentable carbohydrates from the diet. This combination leads to the production of organic acids as a result of the metabolic process of the bacteria, of which the main one is lactic acid, though other weak acids, such as ethanoic and propanoic can also occur [11]. These acids dissolve the mineral component of the tooth, leading to loss of structure. 

In a recent study, which followed children with mildly elevated levels of dentin (tooth) lead in early childhood, adolescents were found to fail at school seven times as often as those with lower lead levels, and to be six times more likely to have reading disabilities. Moderately... 

Mackie et al, (1977) were unable to demonstrate a correlation between tooth lead levels and residence near a potential industrial source. House dust was implicated as a major source of lead by Charney et al, (1980), and Walter et al, (1980) were able to show that household dustiness was significantly related to blood lead in children under 2 years. Soil lead may also be an important source of ingested lead between 2 and 7 years. There was also a slight effect of the occupational category of the fathers. It can be seen that the cause of moderate blood lead elevation is likely to be multifactoral no single source can account for elevated levels in all children. Milar et al, (1980) noted that the intellectual deficits previously attributed to lead may be related to a compromised home environment. 

A further problem relating to the use of blood leads is that of the accuracy of the reported values. Extreme care is required in the sampling and analysis in order to obtain reliable results. Studies have revealed wide discrepancies between results obtained in different laboratories, which must caution against the uncritical acceptance of reported blood leads, especially at the lower blood lead levels [17]. This would also seem to apply to measurements of tooth lead concentrations. Greater care is now exercised and workers often report their efforts to establish accuracy through participation in interlaboratory schemes. 

Fig. 7.9 Teachers negative ratings on classroom behaviour in relation to tooth lead concentration (based on [23]).

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