Gulson B L
Graduate School of the Environment, Macquarie University, Sydney, NSW, Australia.
Environ Health Perspect. 1996 Mar;104(3):306-12. doi: 10.1289/ehp.96104306.
The sources and intensity of lead exposure in utero and in early childhood were determined using stable lead isotopic ratios and lead concentrations of incisal and cervical sections of deciduous teeth from 30 exposed and nonexposed children from the Broken Hill lead mining community in Australia. Incisal sections, consisting mostly of enamel, generally have low amounts of lead and isotopic compositions consistent with those expected in the mother during pregnancy. Cervical sections, consisting mostly of dentine with secondary dentine removed by resorption and reaming, generally have higher amounts of lead than the enamel and isotopic compositions consistent with the source of postnatal exposure. There are statistically significant differences in lead concentrations between incisal and cervical sections, representing within-tooth variation, for children with low and high lead exposure (p = 0.0007, 2 x 10(-6), respectively) and for those who have ingested leaded paint (p = 0.009). Statistically significant differences between incisal and cervical sections in these three exposure groups are also exhibited by the three sets of lead isotope ratios (e.g., p = 0.001 for 206Pb/204Pb ratio in the low exposure group). There are statistically significant differences between the low and high lead exposure groups for lead concentrations and isotopic ratios in incisal (p = 0.005 for lead concentration and 6 x 10(-6) for 206Pb/204Pb ratio) and cervical sections (p = 5 x 10(-5) for lead concentration and 6 x 10(-6) for 206Pb/204Pb ratio). The dentine results reflect an increased exposure to lead from the lead-zinc-silver mineral deposit (orebody lead) during early childhood, probably associated with hand-to-mouth activity. Leaded paint was identified as the source of elevated tooth lead in at least two cases. Increased exposure to lead from orebody and paint sources in utero was implicated in two cases, but there was no indication of previous exposure from the mothers' current blood leads, suggesting an acute rather than a chronic exposure for the mothers. Permanent teeth from one subject had lower amounts of lead in the roots compared with the crowns, and the isotopic composition of the crowns were consistent with the data for the deciduous teeth from the same subject. Based on changes in the isotopic composition of enamel and dentine, it is provisionally estimated that lead is added to dentine at a rate of approximately 2-3% per year.
利用稳定铅同位素比率以及来自澳大利亚布罗肯希尔铅矿社区30名有铅暴露和无铅暴露儿童乳牙切端和牙颈部切片的铅浓度，确定了子宫内和幼儿期铅暴露的来源及强度。切端切片主要由牙釉质组成，铅含量通常较低，其同位素组成与孕期母亲体内预期的一致。牙颈部切片主要由牙本质组成，已通过吸收和扩孔去除了继发性牙本质，其铅含量通常高于牙釉质，同位素组成与出生后暴露源一致。对于低铅暴露和高铅暴露儿童（p值分别为0.0007、2×10⁻⁶）以及摄入含铅油漆的儿童（p = 0.009），切端和牙颈部切片之间的铅浓度存在统计学显著差异，代表牙内差异。这三组铅同位素比率也显示了这三个暴露组切端和牙颈部切片之间的统计学显著差异（例如，低暴露组中²⁰⁶Pb/²⁰⁴Pb比率的p = 0.001）。低铅暴露组和高铅暴露组在切端（铅浓度的p = 0.005，²⁰⁶Pb/²⁰⁴Pb比率的p = 6×10⁻⁶）和牙颈部切片（铅浓度的p = 5×10⁻⁵，²⁰⁶Pb/²⁰⁴Pb比率的p = 6×10⁻⁶）的铅浓度和同位素比率存在统计学显著差异。牙本质结果反映出幼儿期来自铅锌银矿床（矿体铅）的铅暴露增加，可能与手口活动有关。在至少两例中，含铅油漆被确定为牙齿铅含量升高的来源。在两例中涉及子宫内来自矿体和油漆源的铅暴露增加，但没有迹象表明母亲当前血铅存在既往暴露，这表明母亲是急性而非慢性暴露。一名受试者的恒牙牙根中的铅含量低于牙冠，牙冠的同位素组成与该受试者乳牙的数据一致。根据牙釉质和牙本质同位素组成的变化，初步估计铅以每年约2 - 3%的速率添加到牙本质中。
