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This commentary considers the long arc of lead (Pb) poisoning from antiquity to the 21st century. While Pb exposure is commonly attributed to paint or water, this article aims to discuss the underrecognized impacts of air Pb and soil Pb and to address controversial misconceptions related to these exposure sources. The Roman Aristocracy experienced lead poisoning mainly from the ingestion of foods, lead cookware, and lead-contaminated water and wine, but by the 20th century, lead exposure occurred by ingestion and inhalation. The introduction of tetraethyl lead (TEL) additives in gasoline was approved in 1925 in the US and produced an exponential increase in inhalable air lead exhaust particles through the 1970s. These five decades of widespread lead aerosol exposure were enabled by the Lead Industries Association (LIA), which confounded pediatricians, healthcare providers, and government agencies by promoting lead-based paint as the primary agent of childhood lead exposure. Empirical evidence of lead poisoning, environmental exposures, and proactive lead prevention in the general population was impossible until analytical instruments became commonly available for clinical studies and environmental measurements in the 1960s and 1970s. Soil studies in Baltimore, Maryland, beginning in the mid-1970s, indicated that lead particles exhausted from vehicles fueled by leaded gasoline excessively contaminated urban soils compared with non-urban soils. The invisible lead-contaminated air fouled multiple exposure routes via inhalation and ingestion. In addition to misunderstandings about sources of lead exposure, misinformation currently abounds regarding the timeline of banning lead in gasoline. The US Center for Disease Control (CDC) lists the ban as beginning in 1996. The banning of leaded gasoline first occurred in Japan starting in 1972, and after a 1984 Senate Hearing, the US Congress agreed on a rapid phasedown. A US Environmental Protection Agency (EPA) timeline confirmed that most leaded gasoline was banned by the end of 1986. Banning leaded gasoline was associated with sharp declines in the US population’s blood lead, which prompted global efforts to ban leaded gasoline. The eventual result was a complete global ban on highway use of leaded gasoline achieved in August 2021. Leaded gasoline is still used in piston-engine aircraft and the US EPA is proceeding to complete the ban on lead additives in fuel. Using precautionary principles to recover lead-contaminated urban environments and prevent new toxicant exposures are essential challenges and opportunities for present and future generations. 

The knowledge of unsustainable human and Earth system interactions is widespread, especially in light of systemic environmental injustices. Systems science has enabled complex and rigorous understandings of human and Earth system dynamics, particularly relating to pollution of Earth’s land, water, air, and organisms. Given that many of these systems are not functioning sustainably or optimally, how might this field enable both rigorous understanding of the issues and experiments aimed at alternative outcomes? Here, we put forth a novel, multiscale systems science approach with three steps: (1) understanding the systemic issues at hand, (2) identifying systemic interventions, and (3) applying experiments to study the efficacy of such interventions. We illustrate this framework through the ubiquitous and yet frequently underrecognized issue of soil lead (Pb). First, we describe the systemic interactions of humans and soil Pb at micro-, meso-, and macroscales in time and space. We then discuss interventions for mitigating soil Pb exposure at each scale. Finally, we provide examples of applied and participatory experiments to mitigate exposure at different scales currently being conducted in New York City, NY, USA. We put forth this framework to be flexibly applied to contamination issues in other regions and to other pressing environmental issues of our time.