Gulson B L, James M, Giblin A M, Sheehan A, Mitchell P
Graduate School of the Environment, Macquarie University, Sydney NSW, Australia.
Sci Total Environ. 1997 Oct 20;205(2-3):271-5. doi: 10.1016/s0048-9697(97)00198-8.
The variation in lead concentration was measured by thermal ionisation mass spectrometry isotope dilution in household tap water throughout the day when the plumbing system was not fully flushed. After collection of an initial 125-ml water sample containing 119 micrograms/l and a 2-l sample, 125-ml samples were collected at hourly intervals for 8 h. The concentrations in the hourly samples remained in the range 35-52 micrograms/l compared with 1.7 micrograms/l for fully flushed water. High precision lead isotopic measurements showed that approximately 50% of the lead in these water samples derives from the tap 'housing' compared with the overall household system. A health risk assessment was performed employing the US Environmental Protection Agency Integrated Exposure Uptake Biokinetic Model. Predicted blood lead levels in infants only exceeded the 'levels of concern' of 10 micrograms/dl when 100% of the water consumed contained 100 micrograms Pb/1. It would appear that unless the infant consumed 100% of first flush water at lead concentrations of approximately 100 micrograms/l, the blood lead would not exceed the recommended 'level of concern'. However, if more than 0.51 was consumed in drinks and formulae using first flush water, then the blood lead could easily exceed the recommended level. Likewise, a pregnant mother could be at risk of consuming considerably more than the 0.51/day first flush water of the concentrations measured, or throughout the day, if the system were not fully flushed.
在管道系统未完全冲洗的情况下，通过热电离质谱同位素稀释法测量了全天家庭自来水中铅浓度的变化。采集了初始的125毫升含铅量为119微克/升的水样和一个2升的水样后，每小时采集125毫升水样，共采集8小时。每小时采集的水样中铅浓度保持在35 - 52微克/升的范围内，而完全冲洗后的水中铅浓度为1.7微克/升。高精度铅同位素测量表明，与整个家庭系统相比，这些水样中约50%的铅来自水龙头“外壳”。采用美国环境保护局综合暴露吸收生物动力学模型进行了健康风险评估。只有当婴儿饮用的100%的水含铅量为100微克/升时，预测的婴儿血铅水平才会超过“关注水平”10微克/分升。看起来，除非婴儿饮用100%铅浓度约为100微克/升的初冲水，血铅才不会超过推荐的“关注水平”。然而，如果在使用初冲水的饮品和配方奶中饮用超过0.5升，那么血铅很容易超过推荐水平。同样，如果系统未完全冲洗，孕妇每天可能会摄入远超测量浓度下0.5升的初冲水，或者一整天都在饮用。
