Does organic farming reduce the content of Cd and certain other trace metals in plant foods? A pilot study

The effect of organic cultivation systems on the level of Cd in wheat was s tudied in two consecutive harvests. Additionally, the concentrations of Cd, Pb, Cr and Zn were analysed in single harvests of rye, carrots and potatoe s from different farming systems. Wheat and rye were obtained from controll ed field trials using several conventional and ecological systems at two se parate locations in Sweden. Potatoes and carrots were collected at private farms with conventional or ecological production. These farms were juxtapos itioned and had similar soil properties. The levels of Cd in the wheat did not correlate with the cultivation system or the Cd content in the soil. Co nventionally grown wheat from one field trial showed a significantly higher Cd level compared with ecologically grown wheat, while in the other field trial significantly lower Cd levels were detected in the conventionally gro wn wheat. No statistically significant differences in the concentrations of Cd, Pb, Cr or Zn in rye, carrots and potatoes were detected between the cu ltivation systems. The results indicate that organic farming, at least in t he short term, does not necessarily result in reduced levels of Cd and othe r potentially harmful metals in foods of vegetable origin. Factors other th an cultivation system may be of greater importance for the final concentrat ion of Cd and other metals in plant foods. (C) 2000 Society of Chemical Ind ustry.