Lead accumulation in teeth as a function of age with different exposures.

Abstract

The level of lead exposure in industrial, urban, and rural populations has been evaluated by sampling permanent teeth gathered from three regions of Belgium. When tooth lead concentrations are plotted against tooth age, a linear function appears to fit the empirical results satisfactorily. On the contrary, comparing only the arithmetical means of the three samples would bring a possible bias of the results because their mean ages are different. The slope of the three best regression lines obtained respectively with data from the three regions increases significantly in the sequence rural < urban < industrial. A simplified mathematical model shows that this slope is directly related to the mean intake of lead under uniform exposure. It is suggested that this slope could be used as an index of the population's exposure to lead.The blood lead (Pb-B) or the free erythrocyte protoporphyrin (FEP) concentrations, or both, are the most commonly used indicators of lead exposure in population surveys. They have both been used to define a "no-effect" lead concentration for children's exposure or a threshold for undue lead absorption. This threshold value has been repeatedly adjusted downwards during the past 20 years as new data have become available on the epidemiology of subclinical effects of low chronic lead exposure.The blood lead concentration is an "instantaneous" indicator that reflects immediate exposure by giving a static picture of a dynamic process that includes intake, excretion, and tissue storage. Changing the conditions of exposure (or intake) leads to a Pb-B variation within about 28 days,' and it is not, therefore, a reliable index of long-term exposure.2 3 The rate at which the free erythrocyte protoporphyrin concentration in blood changes after cessation of exposure is not known.The concentration of lead in teeth, on the contrary, is a cumulative function of earlier exposure. This retrospective look allows the identification of undetected cases of undue lead absorption whenever other indices have returned to normal. In addition, the storage of lead in the teeth of primates has been shown to be dose-dependent.4 Low but continuous lead exposure will thus be shown by the tooth lead Material and methods SAMPLINGSince May 1978 131 permanent teeth, decayed and non-decayed, have been sampled at random from children and adults of both sexes undergoing treatment in private practices or dental schools in Brussels, Hoboken, and Arlon. Clinical data and inquiry cards indicated possible treatments undergone before extraction. Teeth filled with materials suspected to contain lead were discarded. Other information (age, sex, job, home, working or school address, time spent in each place) was noted in order to assess so far as possible sources of lead exposure and their respective contribution to the total exposure of each subject. ANALYSISThe teeth were ashed for 12 hours at 450°C, then crushed. The powders were ashed for a further four hours at the same temperature, then moistened for one hour. Finally, aft...

Bone lead content assessed by L-line x-ray fluorescence in lead-exposed and non-lead-exposed suburban populations in the United States.

“…Mean tibial Pb levels in each of the three age groups of Throop, where all residents lived within 1 mile of the factory, were significantly higher than baseline. The bone Pb levels reported here for both suburban communities were comparable to those in other studies of normally and excessively exposed children (6,(26)(27)(28), in teenagers (16,29), and in adults (18,19,30,31) measured by KXRF and by atomic absorption spectroscopy (AAS). For instance, Pb concentrations of 2-5 ppm (wet weight), measured by AAS, have been reported in the whole teeth of normally exposed children (6), compared with values of 12-18 ppm in smelter-exposed children (27,28).…”

Significance of teeth lead accumulation in age estimation

“…6 The concentration of lead in teeth is a cumulative meaning of earlier exposure, contrary to blood lead concentration, which is an "instantaneous" indicator that reflects immediate exposure. 7 Lead exposure can thus be shown by means of teeth lead concentration. Dentin is the main site for lead deposition and has been shown to provide evidence of early exposure until the time the tooth is extracted.…”

Characterizing Golden Eagle Risk to Lead and Anticoagulant Rodenticide Exposure: A Review

“…Teeth have been analyzed for lead using AAS and ASV (Rabinowitz et al 1989;Steenhout and Pourtois 1981). Samples must be dry ashed or digested with acid prior to analysis.…”

“…Accumulation of lead in dentin of permanent teeth may continue for the life of the tooth (Steenhout 1982;Steenhout and Pourtois 1981). Because it is in direct contact with the external environment, enamel lead levels may be more influenced than dentin lead by external lead levels and tooth wear (Purchase and Fergusson 1986).…”