Silica-coated calcium pectinate formulations for controlling carbendazim release: water and soil release studies.

This study aims to encapsulate the fungicide carbendazim using a biodegradable polymer (pectin). First, we have obtained calcium pectinate beads (CPG-Carb) by ionotropic gelation using calcium ions as a crosslinking agent. These beads were then coated with silica starting from tetraethoxysilane (TEOS), by a sol-gel process to form hybrid beads (CPG-Carb-SG). The morphology, composition and structure of both beads were characterized and the controlled release assays of the fungicide were studied in both water and soil columns. The encapsulation efficiency for CPG-Carb was slightly higher (75%) compared to CPG-Carb-SG (67%) due to carbendazim loss during the impregnation and condensation steps. The release rate in water and soil columns was about 4 times lower for CPG-Carb-SG than CPG-Carb demonstrating the efficiency of the silica coating to delay the release of carbendazim. Moreover, the release of CPG-Carb-SG is due to the erosion of the silica layer during the first two weeks. After this period, the silica layer was degraded, and the release is then controlled by the swelling of the organic part of the bead as observed for CPG-Carb. Finally, the biodegradability of the pectin, and the release profile make such systems promising candidates for sustained and economical pesticide delivery systems.

Pesticide residues in traditional and industrial honey marketed in Morocco and potential health risk.

This study evaluated the presence of the three pesticides methomyl (MET), carbendazim (CBZ) and chlorpyrifos-ethyl (CPE), as well as the degradation product of CPE (3,5,6-trichloro-2-pyridinol; TCP), in 44 honey samples from all 12 regions of Morocco. With a validated HPLC-UV method occurrence frequencies of 63.6% for MET, 54.5% for CBZ, 95.1% for CPE and 34.1% for TCP were obtained, even at concentrations higher than the maximum residue limits for MET, CPE and TCP. Based on the predominant pesticide, principal component analysis separated sampling regions into three groups. Risk assessment indicated that ingestion of these pesticides, alone or in combination, in honey did not pose a risk to consumers (HQ and HI < 1).