Accumulation of MSMA in the fruit of the blackberry (Rubus sp.).

Abstract

The organic arsenical herbicide, MSMA, is used extensively for weed control along highway rights of way. Residues of the herbicide in edible crops growing near roadsides are of health concern since these products are accessible year round for harvesting by the unsuspecting public. This study examined the uptake and concentration of MSMA in the fruit of the blackberry during the various stages of maturation following the recommended application of 3.37 kg MSMA/hectare. MSMA-Aso accumulated with uptake being greatest in the earliest stages of fruit development. Arsenic levels consistently increased to concentrations of 25-30 microgram/g during one week following herbicide application to green fruit. Uptake during the later stages of development reached approximately 12.5 microgram/g in red and ripe fruit respectively. At all stages, uptake of herbicide in berries exceeded concentrations applied topically, indicating a major source of arsenic through transport from stems and leaves. Berries also absorbed herbicide following topical application to the fruit which is a significant source of arsenic following application in the later stages of development. The movement of herbicide to ripening fruit can be described by a three compartment model in which arsenic gains access from the surface of the berry and by translocation from stems and leaves. Parameter estimates for the model appear in the text.