The urban lead (Pb) burden in humans, animals and the natural environment.

Centuries of human activities, particularly housing and transportation practices from the late 19th century through the 1980's, dispersed hundreds of millions of tons of lead into our urban areas. The urban lead burden is evident among humans, wild and domesticated animals, and plants. Animal lead exposures closely mirror and often exceed the lead exposure patterns of their human partners. Some examples: Pigeons in New York City neighborhoods mimicked the lead exposures of neighborhood children, with more contaminated areas associated with higher exposures in both species. Also, immediately following the lead in drinking water crisis in Flint MI in 2015, blood lead levels in pet dogs in Flint were 4 times higher than in surrounding towns. And combining lead's neurotoxicity with urban stress results in well-characterized aggressive behaviors across multiple species. Lead pollution is not distributed evenly across urban areas. Although average US pediatric lead exposures have declined by 90% since the 1970s, there remain well defined neighborhoods where children continue to have toxic lead exposures; animals are poisoned there, too. Those neighborhoods tend to have disproportionate commercial and industrial lead activity; a history of dense traffic; older and deteriorating housing; past and operating landfills, dumps and hazardous waste sites; and often lead contaminated drinking water. The population there tends to be low income and minority. Urban wild and domesticated animals bear that same lead burden. Soil, buildings, dust and even trees constitute huge lead repositories throughout urban areas. Until and unless we begin to address the lead repositories in our cities, the urban lead burden will continue to impose enormous costs distributed disproportionately across the domains of the natural environment. Evidence-based research has shown the efficacy and cost-effectiveness of some US public policies to prevent or reduce these exposures. We end with a series of recommendations to manage lead-safe urban environments.

Lead seasonality in humans, animals, and the natural environment.

Lead adversely impacts the health of humans, animals, and the natural environment. Higher lead burdens in warm weather occur in humans, domesticated and wild animals; land and water species; urban and rural, developed and pristine environments. The array of evidence suggests that lead seasonality is multifactorial within the natural world, including humans. Seasonally higher temperatures, solar radiation, humidity and anthropogenic pollution result in lower pH (acidification) in air, water and soil. Environmental acidification increases lead's bioavailability and mobility thus intensifying human, animal and plant exposures. In addition, lead seasonality in the biosphere is influenced by higher growth rates, slightly increased exposures, and more Vitamin D metabolism. Methodologically, we applied a One Health perspective to EPA's Integrated Science Assessments of Lead to review the published literature, supplemented with subsequent and related publications to assess data on the seasonality of lead exposure across species and through the earth's systems. Our integrated assessment suggests that: 1) 'Seasonality' is a multifactorial, terrestrial phenomenon affecting the natural world; human activities have exacerbated natural cyclicities that impact lead exposures across species. 2) To be sustainable, human lead remediation strategies must consider the total environment. 3) Global warming and climate change events may increase lead exposures and toxicity to all species throughout the natural environment.

Subclinical Lead Exposure Among Backyard Chicken Flocks in Massachusetts.

Ownership of backyard chickens (BYCs) is increasing in urban areas, and BYCs often have access to soil around the home. Exposure to lead-contaminated soil is a known health risk for people; however, the degree to which BYCs are exposed is unknown. We employed a cross-sectional convenience sample to assess blood lead levels (BLLs) in 57 BYCs from 30 flocks in a region with established environmental lead contamination. Over two-thirds (70.2%) had detectable levels of lead in their blood, which averaged 12.5 µg/dL (range: <3.3 µg/dL to ≥65.0 µg/dL). No chickens demonstrated clinical evidence of lead toxicosis. Almost all owners (96.2%) reported that their chickens had free access to soil, and almost three-quarters (69.2%) of the participants reported giving their chickens unrestricted access to the property. Our findings demonstrate that subclinical but elevated BLLs are common in BYCs that live in an environment where lead contamination may be present. Our data support the inclusion of blood lead testing in the routine veterinary care of BYCs, especially in areas where historic use of leaded paint and environmental lead contamination are reported.