TABLE 1
Case 1: Lead Isotope Ratios With Standard Error and Concentration for Whole Blood and Environmental Sources Sampled for Lead Isotope Analysis
206 Pb/ 204 Pb 2 σ /√n
207 Pb/ 204 Pb 2 σ /√n
207 Pb/ 206 Pb 2 σ /√n
208 Pb/ 206 Pb 2 σ /√n Lead (Pb) Concentration
Sample #
Sample
Sample Type
1 2
5-min flush Tap water
19.1288 0.0007 15.6850 0.0006 0.81997 0.00001 2.02814 0.00003 0.501 µg/L 19.2560 0.0006 15.7004 0.0005 0.81535 0.00001 2.01897 0.00003 0.514 µg/L
Kitchen first draw Living room carpet floor
Tap water
3
Wipe
18.6609 0.0007 15.6362 0.0007 0.83792 0.00001 2.05779 0.00004 1.43 µg/ft 2
4
Child’s bedroom trough
Wipe
20.8818 0.0006 15.8365 0.0005 0.75839 0.00001 1.92719 0.00003 193 µg/ft 2
5
Living room front trough Kitchen floor Child’s carpet floor
Wipe
20.4126 0.0007 15.7959 0.0006 0.77383 0.00001 1.95307 0.00003 10.9 µg/ft 2
6 7
Wipe Wipe
19.0898 0.0006 15.6850 0.0005 0.82165 0.00001 2.03461 0.00003 0.458 µg/ft 2 18.9164 0.0007 15.6667 0.0007 0.82821 0.00001 2.04463 0.00003 0.421 µg/ft 2
8
Solder
Solder (metal)
18.8035 0.0006 15.6916 0.0006 0.83452 0.00001 2.08079 0.00004 36.206 µg/g
9
Soil (side D)
Soil
19.1292 0.0007 15.6883 0.0007 0.82014 0.00001 2.03425 0.00003
136 µg/g
10 Child’s
Paint
20.6180 0.0008 15.8147 0.0006 0.76703 0.00001 1.94195 0.00003 8,696 µg/g
window jamb
11 Living room window jamb 12 Subject initial blood draw 13 Subject second blood draw
Paint
21.5600 0.0008 15.8954 0.0006 0.73727 0.00001 1.89251 0.00003 7,766 µg/g
Whole blood Whole blood
20.4675 0.0012 15.8006 0.0009 0.77199 0.00001 1.95093 0.00004 11.1 µg/dl
20.7182 0.0006 15.8223 0.0005 0.76369 0.00001 1.93683 0.00003 15.4 µg/dl
Note. The report unit for the lead isotope ratio is the atom ratio.
Certified risk assessors conducted a lead- based paint risk assessment and administered the Resident Questionnaire for Investigation of Children With Elevated Blood Lead Lev- els from the U.S. Department of Housing and Urban Development (HUD, Form 16.1). An environmental health specialist from the Wisconsin Department of Health Services obtained environmental samples for LIA. This case series was deemed by the Wis- consin Department of Health Services to con- stitute public health surveillance and prac- tice, thus review by an institutional review board was not required. Lead-Based Paint Risk Assessment Lead in surface coatings was identified using an X-ray fluorescence instrument to determine lead loading in mg/cm 2 . Lead- based paint was defined as ≥0.7 mg/cm 2 and
a lead dust hazard as ≥40 µg/ft 2 on a floor, 200 µg/ft 2 on a windowsill, and 1,200 ppm in soil (Supplemental Text, www.neha.org/ jeh-supplementals).
Soil samples were digested using a combina- tion of nitric and hydrofluoric acids. Lead was purified from samples using the standard anion exchange technique (Strelow & Toerien, 1966). Lead isotopic analysis was performed using Tl-doping on a Nep- tunePlus multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS). Total lead concentrations of the analyzed materials were estimated using the dilution factors and standard concentrations used for the isotopic analysis. Full sample prepara- tion and analytical details are provided in the Supplemental Text. Results from LIA were used to calculate major (ratios not including Pb 204 ) and minor (ratios includ- ing Pb 204 ) isotopic ratios. These ratios were qualitatively compared with isotopic ratios from blood samples to identify the likely source of exposure.
Isotope Sample Preparation and Analysis
All acid reagents used for laboratory proce- dures were Optima grade purchased from Fisher Scientific. Different sample types required slight modifications to digestion and preparation procedures prior to purifica- tion. Tap water samples (first draw and 5-min flush) were collected in clean 2-L fluorinated ethylene propylene bottles and dried in 1-L polytetrafluoroethylene (PFA) jars. Dust wipes, paint samples, pipes and solder, spices, cosmetics, and whole blood were digested in PFA jars on a hotplate using combinations of concentrated nitric and hydrochloric acids.
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