Persistence and effects of rotenone on oil quality in two Italian olive cultivars

The aims of this work are to assess the persistence of rotenone in oil and drupes of olive plants of cultivars Nocellara del Belice (NB) and Cassanese (CA), and to compare the quality of oils from rotenone-treated and untreated plants. Samples of drupes and oil were analyzed at 2, 12, 22 and 30 days after treatment. Rotenone levels in drupes of treated plants declined by about 50% after 22 days from treatment (0.037 mg kg−1 in NB and 0.039 mg kg−1 in CA), whereas the respective values in the oil were higher (0.209 mg kg−1 in NB and 0.229 mg kg−1 in CA) and had a lower decay half-life (4.02 days in NB and 4.71 days in CA). For both cultivars, no significant differences in oil physicochemical and nutritional parameters were found between the two treatments. The panel test of oils extracted after 22 days did not reveal significant differences in unpleasant aromatic notes nor defects between the two treatments. Our results confirm that serious doubts remain about the safety and healthiness of oils extracted from drupes treated with rotenone. This information could assess the real risk in the use of this product for plant protection in olive growing.