Spatial Detection of Pb in Life Sciences: Advances and Limitations.

Lead (Pb) is a significant worldwide environmental contaminant. Elevated blood-lead levels during childhood can affect development and are associated with cognitive impairments, learning disabilities, and attentional deficits later in life. Clinical and toxicological assessments of Pb exposure are generally limited to blood lead level (BLL) tests. BLLs are a transient measure of Pb, as Pb itself distributes and deposits all throughout the body, including all major organs, bones, and the central nervous system. Understanding how BLLs relate to systemic and cellular Pb uptake is crucial for guiding treatments and therapies, yet tissue biopsies of the nervous system in otherwise healthy patients are often infeasible. Researchers have access to controlled experimental models to determine causal actions of Pb but are currently faced with limited options and techniques due to access and cost. While there have been many advances in spatial Pb detection since the early 1900s, they have not always translated to biological sciences as naturally as other research areas, such as geology or material sciences. We propose this is largely because of sample preparation, sample size, and imaging parameters (e.g., depth, scanning area, etc.). There is an urgent need for awareness of this gap in technology and the utility it will play in advancing our knowledge of Pb-induced health conditions. In this review, we discuss the various methods used to spatially detect and visualize Pb within biological samples, with special emphasis on the lack of tractable Pb detection techniques capable of generating spatial information in biological samples. We also discuss modern developments and advancements, emerging techniques in Pb detection, and suggested applications for future research endeavors.