Lead quantities in plants, soil, and air near some major highways in southern California

The lead contents of 27 varieties of consumer crops and plants sampled at various distances from some major highways in south ern California and in local markets were carefully determined. Amounts in and on crops grown close to these highways were shown to be influenced by (a) distance from the highway, (b) extent of plant surface exposed, (c) external plant characteristics, (d) duration of plant exposure, (e) motor vehicle traffic density, and (f) direction of prevailing winds. In soils and suspended air particulates, concentrations of lead were influenced by distance from highway and direction of prevailing winds. All results dem onstrated that lead accumulations in and on plants next to these highways in southern California were caused principally by aerial deposition and not by-at least to any great extent-absorption by the plant from lead-contaminated soil.