Estimated lead (Pb) exposures for a population of urban community gardeners

Abstract

Urban community gardens provide affordable, locally grown, healthy foods and many other benefits. However, urban garden soils can contain lead (Pb) that may pose risks to human health. To help evaluate these risks, we measured Pb concentrations in soil, vegetables, and chicken eggs from New York City community gardens, and we asked gardeners about vegetable consumption and time spent in the garden. We then estimated Pb intakes deterministically and probabilistically for adult gardeners, children who spend time in the garden, and adult (non-gardener) household members. Most central-tendency Pb intakes were below provisional total tolerable intake (PTTI) levels. High-contact intakes generally exceeded PTTIs. Probabilistic estimates showed approximately 40% of children and 10% of gardeners exceeding PTTIs. Children’s exposure came primarily from dust ingestion and exposure to higher-Pb soil between beds. Gardeners’ Pb intakes were comparable to children’s (in µg/d) but were dominated by vegetable consumption. Adult household members ate less garden-grown produce than gardeners and had the lowest Pb intakes. Our results suggest that healthy gardening practices to reduce Pb exposure in urban community gardens should focus on encouraging cultivation of lower-Pb vegetables (i.e., fruits) for adult gardeners and on covering higher-Pb non-bed soils accessible to young children. However, the common practice of replacement of root-zone bed soil with clean soil (e.g., in raised beds) has many benefits and should also continue to be encouraged.

Ecosystem (Dis)benefits Arising from Formal and Informal Land-Use in Manchester (UK); a Case Study of Urban Soil Characteristics Associated with Local Green Space Management

“…Sites used in this way exhibited an elevated concentration of soil borne contaminants with mean concentrations of lead at allotment and garden sites well above UK Environment Agency soil guideline values (SGVs) [57] for human exposure. Given that the design and management of vegetable gardening approaches often leaves large areas of bare earth between crops, exposure to humans from direct contact with the soil and through dust and air-borne contaminants is exacerbated [72,73] relative to sites with more extensive ground flora, as at park and orchard sites. Moreover, allotment and garden sites in the present study were located, as they often are, in close proximity to roadsides and, therefore, anthropogenic sources of pollution, whereas orchards were situated within areas of more expansive green space.…”

“…As such, the latter may have been further buffered from such exposures. Orchards also benefited from greater vertical as well as horizontal vegetation cover which may provide a further screening effect [73] acting as a form of self-protection. In the case of community garden soils sampled in our study, these had the highest concentrations of lead and zinc, likely the result of their occurrence on vacant, previously derelict industrial (contaminated) land, upon which such collectively managed projects are often created [3,13].…”

Constructed Technosols are key to the sustainable development of urban green infrastructure

“…There is a significant body of work examining the possibilities and challenges of urban farming, but most research on this topic does not necessarily examine the soil that literally lays the ground for such endeavors. The most common attention given to urban agriculture soils pertains to the presence of inorganic and organic contaminants (Brown et al, 2016;Kessler, 2013;Marquez-Bravo et al, 2016;McBride et al, 2014;Mitchell et al, 2014;Sipter et al, 2008;Spliethoff et al, 2016). Both ongoing and historic activities related to industrial processes, use of leaded paint and gasoline, and incineration have left a legacy of potentially toxic elements and compounds in urban soils that create risks for gardeners and others who come into contact with soil (Chillrud et al, 1999;Laidlaw et al, 2017;Mielke et al, 1983;Root, 2015).…”

Sources and Pathways of Lead Contamination in Urban Community Gardens in Toledo, Ohio

“…Targeted geotextile and soil replacement have been shown to reduce BLLs in children (Mielke 2016, Spliethoff et al, 2016, Clark et al, 2008. Compared to wholesale soil replacement, this strategy will be far more affordable targeting drip zones and other areas at the highest risk of Pb contamination.…”

“…Simonetti et al 2000, and Doucet and Carignan (2001) This study represents a continuation of previous work by Stewart et al (2014) in the Toledo area which focused on residential soil samples from yards, schools, and play areas for children ( Figure 2). But based on other studies, community gardens are also an important potential pathway of Pb exposure (Spliethoff et al, 2016;Bugdalski et al, 2014;Clark et al, 2006;Laidlaw et al, 2018, etc.). Therefore it is necessary to expand on the past work on Toledo residential soils by branching out into garden soils and the impact of gardening practices on the distribution of heavy metals, especially lead.…”