Urrestarazu Paola, Villavicencio Germán, Opazo Margaret, Arbildua José, Boreiko Craig, Delbeke Katrien, Rodriguez Patricio H
Center of Ecotoxicology and Chemistry of Metals, Universidad Adolfo Ibañez, Diagonal Las Torres, 2700 Peñalolen, Santiago, Chile.
Environ Health. 2014 Aug 11;13:66. doi: 10.1186/1476-069X-13-66.
Low blood lead levels previously thought to pose no health risks may have an adverse impact on the cognitive development of children. This concern has given rise to new regulatory restrictions upon lead metal containing products intended for child use. However few reliable experimental testing methods to estimate exposure levels from these materials are available.
The present work describes a migration test using a mimetic saliva fluid to estimate the chronic exposure of children to metals such as lead while mouthing metallic objects. The surrogate saliva medium was composed of: 150 mM NaCl, 0.16% porcine Mucin and 5 mM buffer MOPS, adjusted to pH 7.2. Alloys samples, in the form of polished metallic disc of known surface area, were subjected to an eight hours test.
Two whitemetal alloys Sn/Pb/Sb/Cu and three brass alloys Cu/Zn/Pb were tested using the saliva migration protocol. In the case of the whitemetal alloys, first order release kinetics resulting in the release of 0.03 and 0.51 μg lead/cm2 after 8 hours of tests were observed, for lead contents of 0.05-0.07% and 5.5%, respectively. Brasses exhibited linear incremental release rates of 0.043, 0.175 and 0.243 μg lead/cm2h for lead contents of 0.1-0.2%, 1.7-2.2% and 3.1-3.5%, respectively. The linear regression analysis of lead release rates relative to Pb content in brasses yielded a slope of 0.08 μg lead/cm2h%Pb (r2 = 0.92). Lead release rates were used to estimate the mean daily mouthing exposure of a child to lead, according to age-specific estimates of mouthing time behavior. Calculated daily intakes were used as oral inputs for the IEUBK toxicokinetic model, predicting only marginal changes in blood lead levels (0.2 μg lead/dL or less) for children aged 0.5 to 1 years old exposed to either class of alloy.
The results of this study as a whole support the use of migration data of metal ions, rather than total metal content, to estimate health risk from exposure to metals and metal alloys substances in children.
以前认为不会对健康构成风险的低血铅水平，可能会对儿童的认知发育产生不利影响。这种担忧导致了对儿童使用的含铅金属产品出台了新的监管限制。然而，几乎没有可靠的实验测试方法来估计这些材料的暴露水平。
本研究描述了一种使用模拟唾液流体的迁移试验，以估计儿童在咬金属物品时对铅等金属的慢性暴露。替代唾液介质由150 mM氯化钠、0.16%猪粘蛋白和5 mM缓冲液MOPS组成，调节至pH 7.2。以已知表面积的抛光金属圆盘形式的合金样品进行了8小时的测试。
使用唾液迁移方案对两种白色金属合金Sn/Pb/Sb/Cu和三种黄铜合金Cu/Zn/Pb进行了测试。对于白色金属合金，观察到一级释放动力学，在铅含量分别为0.05 - 0.07%和5.5%的情况下，测试8小时后铅的释放量分别为0.03和0.51 μg/cm²。黄铜在铅含量分别为0.1 - 0.2%、1.7 - 2.2%和3.1 - 3.5%时，铅的线性增量释放速率分别为0.043、0.175和0.243 μg/cm²·h。黄铜中铅释放速率相对于铅含量的线性回归分析得出斜率为0.08 μg/cm²·h/%Pb（r² = 0.92）。根据特定年龄的咬物时间行为估计，铅释放速率用于估计儿童每天咬物时对铅的平均暴露量。计算出的每日摄入量用作IEUBK毒物动力学模型的口服输入量，预测0.5至1岁儿童接触任何一类合金时血铅水平仅会有微小变化（0.2 μg/dL或更低）。
本研究的整体结果支持使用金属离子的迁移数据而非总金属含量来估计儿童接触金属和金属合金物质的健康风险。
