Air as a source of lead in edible crops

Abstract

The effect of airborne lead on the lead concentration of the edible and nonedible portions of several important types of food crops was studied by growing crops in greenhouses supplied with filtered and ambient air, and in plots planted in long rows perpendicular to a busy highway. Of the ten crops studied - wheat, potatoes, tomatoes, sweet corn, carrots, cabbage, oats, rice, leaf lettuce, and snap beans - eight were not affected by the concentration of lead in air. In both sets of tests, inedible portions of the plants (bean leaves, corn husks, soybean husks, and oat, wheat, and rice chaff) showed a two- to three-fold increase in lead concentration when grown near the road or in the greenhouse with unfiltered air. The conclusions are reached that lead occurring naturally in the soil is the main source of lead in the edible portion of the crops studied, and that airborne lead, based on the crops studied, contributes 0.5 to 1.5% of the lead content of the US diet.