TABLE 6
Case 6: 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 Cosmetic Cosmetic Cosmetic
1 Lavender powder 2 Baby powder 3 Hindu powder
19.8394 0.0004 15.8828 0.0004 0.80056 0.00001 1.96837 0.00002
0.18 µg/g
–
–
–
–
–
–
–
–
–
19.9784 0.0005 15.8952 0.0004 0.79561 0.00001 1.93069 0.00003
3.41 µg/g 0.07 µg/g
4 Spicy masala powder
Kitchen spice 17.7920 0.0005 15.6231 0.0005 0.87809 0.00001 2.11261 0.00004
5 Turmeric
Kitchen spice 17.8115 0.0004 15.6218 0.0004 0.87706 0.00001 2.11514 0.00002 Kitchen spice 17.5293 0.0007 15.6026 0.0007 0.89008 0.00001 2.14296 0.00004 Kitchen spice 17.8629 0.0007 15.6304 0.0006 0.87502 0.00001 2.10647 0.00003
0.63 µg/g 0.04 µg/g 0.05 µg/g 0.06 µg/g 0.01 µg/g 0.03 µg/g 5.3 µg/dl
6 Masala powder
7 Chili powder
8 Coriander powder Kitchen spice 17.6877 0.0006 15.6154 0.0005 0.88284 0.00001 2.11941 0.00004 9 Health mix powder Kitchen spice 17.9669 0.0019 15.6335 0.0017 0.87016 0.00002 2.11616 0.00005
10 Toothpaste
Cosmetic
18.1945 0.0005 15.7265 0.0005 0.86436 0.00001 2.11029 0.00004
11 Subject initial blood draw 12 Ceremonial bell
Whole blood 17.5476 0.0007 15.5884 0.0006 0.88834 0.00001 2.13368 0.00004
Wipe Wipe Wipe Wipe
17.7146 0.0006 15.6011 0.0005 0.88068 0.00001 2.12352 0.00002 14.6 µg/ft 2
13 Small lamp
17.5312 0.0006 15.5966 0.0005 0.88965 0.00001 2.13170 0.00003 17.4571 0.0004 15.5907 0.0004 0.89309 0.00001 2.13964 0.00003 17.7920 0.0009 15.6135 0.0007 0.87758 0.00001 2.11546 0.00003
0.8 µg/ft 2 4.0 µg/ft 2 0.1 µg/ft 2
14 Incense holder 15 Ceremonial vase
Note. The report unit for the lead isotope ratio is the atom ratio.
being from the same geological deposit as the dominant lead exposure source(s) or the same ratio as the sum of multiple lead expo- sure sources (Supplemental Table). The differences in environmental and blood PbIR between cases 4–6 and cases 1–3 demonstrate how abundances of iso- topes vary given the age of the source lead ore. Cases 1–3 possessed a 208 Pb/ 206 Pb isoto- pic composition range of 1.93–2.06, which is consistent with Midwestern ore deposits (Doe & Delevaux, 1972; Field et al., 2018; Millen et al., 1995; Potra et al., 2018) or Great Lakes precipitation that reflects industrial pollution and coal burning (Sherman et al., 2015). In contrast, cases 4–6 possessed a 208 Pb/ 206 Pb isotopic composition range of 2.13–2.14, which is consistent with anthropogenic lead sources in India (Sen et al., 2016). The high precision aorded by MC-ICP- MS methods is a major strength of our study. Previous LIA case series used sector field/ magnetic sector ICP (Gwiazda et al., 2005; Oulhote et al., 2011) or solid source MS (Gulson et al., 1995; Millen et al., 1995; Yae
et al., 1983) for lead isotopes. The uncertain- ties around PbIR in those studies typically are between 0.1–1% (Gulson et al., 1995; Gwi- azda et al., 2005; Millen et al., 1995; Oulhote et al., 2011; Yae et al., 1983). In contrast, our case-series method using MC-ICP-MS obtained precisions of approximately 0.02– 0.03% in whole blood (Supplemental Table) based on repeat analyses of whole blood stan- dards, although there are still no isotopic ref- erence materials for this purpose. Another strength of our study is our inclu- sion of a wide array of samples, even those with low lead concentrations. Moreover, our study was unique in that case follow-up of BLLs has not been reported routinely in past LIA studies and thus contributes data to the impact of LIA in remediation eorts. There are at least three limitations to our case series. Blood lead isotopic analysis repre- sents all sources of lead—both endogenous or exogenous—which was supplemented by our diverse array of samples but could not account for lead from the mother during gestation or bone storage of lead. Also, mixtures of lead
sources are challenging to interpret and not fully explored. Given that this study is a pilot project and case-series analysis, our sample size limits the generalizability of our results. A further limitation to conducting LIA is the cost and availability of mass spectrometers. Conclusion Overall, our findings suggest that high-pre- cision isotopic analysis with MC-ICP-MS methods could be used as a supplemental tool during lead risk assessment. Our cases demonstrate that LIA can identify recontami- nation from legacy lead and imported items such as spices and cosmetics. All sources of lead exposure are important to consider because lead poisoning aects individuals with infinitely variable behaviors and envi- ronments. Future work should assess the use of LIA on a larger scale and the cost-eective- ness of this technique. Acknowledgements: This study and article were supported in part by an appointment to the Applied Epidemiology Fellowship Pro-
17
May 2023 • our4'l o, 4</ro4me4:'l e'l:.
Powered by FlippingBook