House sparrows as sentinels of childhood lead exposure

Abstract

Our understanding of connections between human and animal health has advanced substantially since the canary was introduced as a sentinel of toxic conditions in coal mines. Nonetheless, development of wildlife sentinels for monitoring human exposure to toxins has been limited. Here, we capitalised on a three-decade long child blood lead monitoring program (> 20,000 measurements), to demonstrate that the globally ubiquitous and human commensal house sparrow (Passer domesticus) can be used as a sentinel of human health risks in urban environments impacted by lead mining. We show that sparrows are a viable proxy for the measurement of blood lead levels in children at a neighbourhood scale (0.28 km2), and could be used to monitor changes in lead exposure risks over time. In support of the generalisability of this approach, the blood lead relationship established in our focal mining city enabled us to accurately predict elevated blood lead levels in children from another mining city using only sparrows from the second location. Using lead concentrations and isotopic compositions from environmental and biological matrices, we identified shared sources and pathways of lead exposure in sparrows and children, with strong links to contamination from local mining emissions. Our findings show how human commensal species can be used to identify and predict human health risks over time and space. Moreover, they affirm the emerging paradigm that humans and animals share these risks, and highlight the true ecological cost of contaminated environments.