High-Precision (MC-ICPMS) Isotope Ratio Analysis Reveals Contrasting Sources of Elevated Blood Lead Levels of an Adult with Retained Bullet Fragments, and of His Child, in Milwaukee, Wisconsin

High-precision Pb isotopes of drinking water lead pipes: Implications for human exposure to industrial Pb in the United States

Millions of lead (Pb) pipes are still used in the drinking water distribution systems in many regions in the world. Human exposure to Pb from contaminated drinking water continues to be of concern in the United States (U.S.), as illustrated by the widely publicized "Flint Water Crisis" in 2015. The Pb isotopic composition of Pb-pipes potentially can be useful to identify human exposure to Pb from lead service lines (LSLs). In addition, as the LSLs were likely manufactured from similar industrial Pb sources as other Pb objects and materials in the USA, the Pb-pipes isotope data can provide information about the overall isotopic composition of the U.S. industrial Pb. In this work we present high-precision Pb isotope data from Pb-pipes excavated from different U.S. municipalities. The Pb-pipes show an extremely wide range of Pb isotopic compositions, with ²⁰⁶Pb/²⁰⁴Pb ranging from 17.004 to 22.010, ²⁰⁷Pb/²⁰⁴Pb from 15.460 to 15.921, and ²⁰⁸Pb/²⁰⁴Pb from 36.687 to 41.120. The wide isotope range is observed even in a single town, suggesting that no regional Pb isotope patterns can be expected within the continental USA. However, the high-precision MC-ICP-MS Pb data form a clear linear trend that, depending on the context, can be used to identify human Pb exposure. Furthermore, as the linear trend is a result of utilization of Pb ores from different domestic and international sources and secondary recycling of metallic Pb, it is likely representative of the overall isotopic composition of the U.S. industrial Pb pool. Therefore, the identified trend is the most accurate isotope representation of the U.S. anthropogenic Pb at present and can be used as first-order evaluation to determine if a person with elevated blood Pb levels was exposed to U.S. industrial Pb sources.

The Use of Pb Isotope Ratios to Determine Environmental Sources of High Blood Pb Concentrations in Children: A Feasibility Study in Georgia

The incidence of lead (Pb) poisoning in children in Georgia has been identified as a major health concern, with a recent national survey identifying that 41% of children aged 2-7 years had blood lead concentrations (BLCs) greater than the blood lead reference value (BLRV) of ≥5 µg dL^-1. This study collected samples of blood, spices, paint, soil, dust, flour, tea, toys, milk, and water from 36 households in Georgia where a child had previously been identified as having a BLC > BLRV. The Pb concentrations of these samples were determined and compared to Georgian reference values. Samples from 3 households were analysed for their Pb isotope composition. The Pb isotope composition of the environmental and blood samples were compared to identify the most likely source(s) of Pb exposure. This approach identified that some spice and dust samples were the likely sources of Pb in the blood in these cases. Importantly, some soil, paint, and dust sources with high Pb concentrations could be discounted as contributing to blood Pb based on their distinct isotope composition. The data presented demonstrate the significant contribution that Pb surveillance and Pb isotope ratio analyses can make to managing Pb exposure in regions where high BLCs are identified.

Retained bullets and lead toxicity: a systematic review

INTRODUCTION

Lead toxicity secondary to retained bullet(s) (RB) after a penetrating gunshot wound is a rare but likely underdiagnosed condition, given the substantial number of firearm injuries in the United States. There is currently no consensus on the indications for surveillance, chelation, or surgical intervention.

OBJECTIVE

The purpose of our review is to summarize the literature on systemic lead toxicity secondary to RBs to help guide clinicians in the management of these patients.

METHODOLOGY

The primary literature search was conducted in Medline (PubMed), EMBASE, Cochrane, and CENTRAL using the following MESH terms: "chelation" and "lead poisoning" or "lead toxicity" or "lead" and "bullet" or "missile" or "gunshot", or "bullet".

RESULTS

The search identified 1,082 articles. After exclusions, a total of 142 articles were included in our final review, the majority of which were case reports. Several factors appear to increase the risk of developing lead toxicity including the location of the RB, the presence of a fracture or recent trauma, number of fragments, hypermetabolic states, and bullet retention duration. Particularly, RBs located within a body fluid compartment like an intra-articular space appear to be at a substantially higher risk of developing lead toxicity. Even though patients with lead toxicity from RBs will have similar symptoms to patients with lead toxicity from other sources, the diagnosis of lead poisoning may occur months or years after a gunshot wound. Symptomatic patients with high blood lead levels (BLLs) tended to improve with a combination of chelation and surgical removal of RBs.

CONCLUSIONS

We suggest surveillance with serial BLLs should be performed. Patients with intra-articular RBs appear to be at increased risk of lead toxicity and if possible, early surgical removal of the RBs is warranted, especially given that signs of toxicity are vague, and patients may not have access to follow-up. Long-term chelation should not be used as a surgical alternative and management should be multidisciplinary.

Children's exposure to environmental lead: A review of potential sources, blood levels, and methods used to reduce exposure

Lead has been used for thousands of years in different anthropogenic activities thanks to its unique properties that allow for many applications such as the manufacturing of drinking water pipes and its use as additives to gasoline and paint. However, knowledge of the adverse impacts of lead on human health has led to its banning from several of its applications, with the main goal of reducing environmental pollution and protecting human health. Human exposure to lead has been linked to different sources of contamination, resulting in high blood lead levels (BLLs) and adverse health implications, primarily in exposed children. Here, we present a summary of a literature review on potential lead sources affecting blood levels and on the different approaches used to reduce human exposure. The findings show a combination of different research approaches, which include the use of inspectors to identify problematic areas in homes, collection and analysis of environmental samples, different lead detection methods (e.g. smart phone applications to identify the presence of lead and mass spectrometry techniques). Although not always the most effective way to predict BLLs in children, linear and non-linear regression models have been used to link BLLs and environmental lead. However, multiple regressions and complex modelling systems would be ideal, especially when seeking results in support of decision-making processes. Overall, lead remains a pollutant of concern and many children are still exposed to it through environmental and drinking water sources. To reduce exposure to lead through source apportionment methods, recent technological advances using high-precision lead stable isotope ratios measured on multi-collector induced coupled plasma mass spectrometry (MC-ICP-MS) instruments have created a new direction for identifying and then eliminating prevalent lead sources associated with high BLLs.

Application of Stable Isotopic Ratio Analysis to Identify the Cause of Acute Versus Chronic Lead Poisoning of a Tundra Swan (Cygnus columbianus): A Case Study

We utilized lead (Pb) stable isotopes to identify the source of acute Pb poisoning in a Tundra Swan (Cygnus columbianus) and evaluated overall Pb exposure. Upon necropsy, we obtained samples of blood, liver, kidney, heart, thigh, breast, femur, and metallic objects (i.e., fishing sinker, spring and swivels) from the gizzard for Pb isotopic analysis. Pb isotope ratios of blood and soft tissues were essentially identical to the Pb ratios of the sinker, the likely source of acute poisoning. The spring and swivels had lower Pb content and ratios distinct from tissue, suggesting no significant contribution to poisoning. Femur Pb isotopic composition was the most distinct biological sample and indicative of a combination of sources. These results demonstrate isotopic analysis as a viable method for determining the source of acute Pb poisoning, and that Pb isotope ratios in bone most likely record a lifetime-averaged metric of Pb exposure.