Tragedy of the Temporal Commons: Soil-Bound Lead and the Anachronicity of Risk

In 2002, a team of researchers from the University of California, Irvine collaborated with the community of Pacoima, California around a co-ordinated effort to analyze soil around the neighborhood for lead. The team found both total and bioavailable lead to be markedly higher in areas close to major highways, almost 20 years after leaded gasoline had been completely phased out. Multi-regression and cluster analyses reveal the association of elevated levels of total and bioavailable lead with proximity to major highways that cut through Pacoima. Moreover, bioavailability ratios are higher next to highways than elsewhere. What this reveals is an unexpected persistence of lead deposited by vehicular emissions over a long period of time, a potentially intractable policy issue. The long residence time of soil lead represents an enduring public health problem, especially considering the numbers of those potentially exposed over time. It is unclear how expedient or realistic the conversion of land use around major highways might be, or how this new information might be integrated into ongoing movements for change. However, some policy actions can, even now, be considered—e.g. a closer policy focus on the bioavailable, not just total, fraction of soil lead. We also reflect upon how these traces in the soil give us a more profound sense of the cumulative burden that some communities have to bear due to a history of neglect.