Healthy Soils, Healthy Communities: Preliminary results for lead and other metals in New York City community garden soils

Urban gardens provide affordable, fresh produce to communities, including those with limited access to healthy food. However, urban gardening may increase exposure to lead and other soil contaminants. Gardeners have asked for support in assessing soil contamination and exposures, prompting formation of a community-research collaboration under NIEHS Partnerships for Environmental Public Health. As a first step, metals analysis was conducted on composite soil samples from growing areas and a discrete sample from a non-growing area in each of 44 actively managed food-producing community gardens in NYC. Median concentrations of arsenic, barium, beryllium, chromium, copper, lead, manganese, nickel, and zinc in growing areas (5.9, 82, 0.2, 13, 35, 88, 213, 10, and 130 ppm, respectively) were lower than median values reported in NYC soil and other urban gardening studies. For all metals except lead, over 90% of the growing areas sampled were within a range of concentrations found in NYS rural soils. However, 61% of gardens had at least one growing area exceeding guidance values (based on rural background concentrations or residential exposure scenarios including gardening) for barium, lead, arsenic, chromium, or zinc (12%, 8%, 3%, 1%, 0.2% of all samples, respectively). With the exception of arsenic and copper, non-growing areas had statistically higher levels than growing areas. Factors associated with higher metals concentrations included lack of raised beds and visible presence of construction debris (e.g., brick chips), suggesting that certain existing active management practices (e.g., importing clean soil) have lowered soil metal concentrations. However, elevation of some contaminants (e.g., lead) above guidance values in communities which may already be burdened by some environmental exposures (e.g., elevated blood lead) suggests that communities could continue to benefit from exposure reduction efforts. Future activities will include working with communities to better understand potential health risks and exposure reduction strategies for soil contaminants.