Lead-sheathed telecom cables and historic leaded gasoline emissions substantially raise environmental lead levels in Portland, Oregon

We conducted a high-resolution study of lead in an urban moss, Orthotrichum lyellii, to better understand lead distributions and sources in Portland, Oregon (United States). The outdoor lead landscape is heterogeneous, with lead concentrations varying with age of neighborhood: on average 8.3× and 19× the rural background in newer (<1948) and older neighborhoods (≤1915), respectively. This study finds leaded gasoline to be a pervasive and persistent lead source, decades after the complete phase out of leaded gasoline use by on-road vehicles. The highest lead levels, up to 590× the rural background, are found in older residential neighborhoods where relic lead-sheathed telecommunication cables were identified. Leaching of lead from these cables is thought to be responsible for elevated lead in older residential neighborhoods in cities across the country. Targeted research is needed to quantify the impact of these cables on lead exposures in affected communities.