RESUMO
California recycles 50% of previously disposed trash. Increased use of yardwastes and composts has raised concern about toxic materials in these products. Oleander is a toxic shrub common to CA landscapes and is frequently clipped and disposed of in greenwaste containers, resulting in concerns about the toxicity of oleander-contaminated yardwastes and composts from these wastes. Information about breakdown of oleandrin (one of the glycoside toxicants of oleander) during composting or the ability of plants to absorb this molecule has not been reported. In separate experiments, we documented the apparent first-order disappearance of oleandrin from composts of pure oleander, with a disappearance half-life of 15 d. Within 50 d, 90% of the oleandrin was removed during aerobic composting in a turned pile. In an amendment study with fresh uncomposted oleander, no oleandrin was detected in tomato and zuchinni fruit, snap beans, carrot tubers, or green lettuce. Oleandrin was found in red leaf lettuce growing in soils mulched with oleander, but oleandrin concentrations were near the detection limit of the assay. Soil from oleander mulched and amended plots contained low levels of oleandrin at the time of harvest.