Evaluation of Barriers to Prevent Lead Contamination of Produce Grown in Urban Gardens

Celine Richard,Heather Kirk-Ballard,Edward Bush,Kathryn Fontenot,M Taylor Bryant

doi:10.4236/jep.2020.1112067

Abstract

High lead (Pb) contamination of soils is a threat to human health. Indirect ingestion occurs within the food chain through activities such as growing vegetables with an ability to accumulate lead in edible tissues. Many university extension systems recommend growing vegetables in raised beds to avoid lead contamination. However, there is limited scientific evidence of the efficacy of raised beds in reducing lead uptake in vegetable crops. To address the soil-lead exposure pathway from garden to consumption, this study supplements gaps in the literature pertaining to raised-bed garden practices by evaluating lining materials. Simulated raised beds were constructed to evaluate barriers (neoprene rubber sheeting, landscape fabric and a no barrier control) placed between contaminated (500 ppm) and uncontaminated garden media. The resulting data suggests that neoprene rubber sheeting is not an effective barrier to prevent lead uptake in vegetable crops. In fact, the neoprene barrier contained elevated amounts of lead contributing to higher levels of lead (p ≤ 0.05) within the plant tissue as compared to a no barrier treatment.

Highlights

Lead (Pb) is a naturally occurring heavy metal that exists at low concentrations (50 ppm) in the environment [1]
There were no significant differences in Pb uptake between the neoprene rubber and landscape fabric barriers nor between landscape fabric and the no-barrier control treatment (Figure 6)
Neither neoprene rubber nor landscape fabric showed a decrease in lead levels in plants grown in experimental plots compared to the no barrier control

Summary

Introduction

Lead (Pb) is a naturally occurring heavy metal that exists at low concentrations (50 ppm) in the environment [1]. Throughout human history, Pb’s prolific use has facilitated its relocation, concentration, and subsequent threat to human health. Through the phase-out of Pb use in products such as gasoline and paints, the amount of Pb used in the United States has generally declined since the mid-1970’s. Leaded gasoline emissions and Pb paint peeling in older buildings can result in suspension and further deposition of Pb on nearby surfaces [3]. Though Pb exists in various compounds, as a basic element it does not readily degrade in the environment and binds tightly to soils, contributing to its persistence as an environmental human health risk [4] [5]

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