title: Lead (Pb) quantification in potable water samples: implications for regulatory compliance and assessment of human exposure.
abstract: Assessing the health risk from lead (Pb) in potable water requires accurate quantification of the Pb concentration. Under worst-case scenarios of highly contaminated water samples, representative of public health concerns, up to 71-98 % of the total Pb was not quantified if water samples were not mixed thoroughly after standard preservation (i.e., addition of 0.15 % (v/v) HNO(3)). Thorough mixing after standard preservation improved recovery in all samples, but 35-81 % of the total Pb was still un-quantified in some samples. Transfer of samples from one bottle to another also created high errors (40-100 % of the total Pb was un-quantified in transferred samples). Although the United States Environmental Protection Agency's standard protocol avoids most of these errors, certain methods considered EPA-equivalent allow these errors for regulatory compliance sampling. Moreover, routine monitoring for assessment of human Pb exposure in the USA has no standardized protocols for water sample handling and pre-treatment. Overall, while there is no reason to believe that sample handling and pre-treatment dramatically skew regulatory compliance with the US Pb action level, slight variations from one approved protocol to another may cause Pb-in-water health risks to be significantly underestimated, especially for unusual situations of "worst case" individual exposure to highly contaminated water.
authors.affiliation: Civil and Environmental Engineering Department, Virginia Tech, 418 Durham Hall, Blacksburg, VA 24061, USA.
authors.forename: Simoni
authors.initials: S
authors.lastname: Triantafyllidou
authors.forename: Caroline K
authors.initials: CK
authors.lastname: Nguyen
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Marc A
authors.initials: MA
authors.lastname: Edwards
mesh_terms: D060766:Drinking Water / Q000737:chemistry*; D004781:Environmental Exposure / Q000032:analysis / Q000706:statistics & numerical data*; D004784:Environmental Monitoring; D058735:Environmental Policy; D019983:Guideline Adherence; D006801:Humans; D007854:Lead / Q000032:analysis*; D011634:Public Health; D014481:United States; D014484:United States Environmental Protection Agency; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014876:Water Pollution / Q000331:legislation & jurisprudence / Q000706:statistics & numerical data*
chemical_list: D060766:Drinking Water; D014874:Water Pollutants, Chemical; D007854:Lead