ARS | Publication request: Level and fate of chlorpropham in potatoes during storage and processing

Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 12, 2008
Publication Date: N/A

Interpretive Summary: Chlorpropham is a pesticide used to control sprouting during long term storage. The objective of the present study was to establish the total chlorpropham residue balance (residues in unwashed and washed whole tubers, peeled tubers, peels, boiled and pureed tubers, and washing and cooking waters) for two potato varieties after uniform application as a function of storage time under different typical storage conditions (in a basement, storehouse, and refrigerator) in Lithuania. This study was conducted using storage conditions typically found in Lithuania and surrounding countries. The tubers were initially stored at three different temperatures, 12 oC in the basement, 4 oC in the storehouse; and 5 oC in the refrigerator. However the temperatures were not uniform throughout the experiment. The only constant temperature was in the refrigerator, whereas the temperature in the basement increased to 17 oC by the end of the experiment in the spring, and the storehouse temperature increased to 12 oC. The results of this study show that chlorpropham concentrations in tubers under these typical conditions were below the recently revised levels that are acceptable for residues in both whole potatoes and peels. Also, in spite of lack of optimum conditions during the varied storage methods, chlorpropham treated tubers did not sprout. The fact remains, however, that chlorpropham residues will be on potatoes as long as it is used for sprout control. While peeling would remove the majority of the chemical, it would also remove nutrients from the potato. It appears that until alternative sprout control methods become commercially available, emphasis of scientists should be placed on developing effective cleaning methods to remove chlorpropham residues from the tuber surfaces.

Technical Abstract: Chlorpropham is a pesticide used to control sprouting during long term storage. The objective of the present study was to establish the total chlorpropham residue balance (residues in unwashed and washed whole tubers, peeled tubers, peels, boiled and pureed tubers, and washing and cooking waters) for two potato varieties after uniform application as a function of storage time under different typical storage conditions (in a basement, storehouse , and refrigerator) in Lithuania. Chlorpropham concentration on washed and unwashed tubers decreased from ~15 mg kg-1 after storage for 28 d to ~9 mg kg-1 after storage for 85 d. Peel concentrations decreased from ~50 mg kg-1 at 5 d after treatment to ~20 mg kg-1 at 85 d after treatment. Whole tuber and peel concentrations were below the recently adopted tolerance levels. The average concentration in the two varieties of peeled tubers in the three storage facilities was 1 mg kg-1. Chlorpropham concentrations in the wash water decreased from 3.5 to 1.0 mg L-1 when the storage time increased from 28 to 85 d. The cooking water concentration similarly decreased, from >0.2 mg L-1 at 28 d after treatment to > 0.1 mg L-1 at 85 d after treatment. The results of this study show that chlorpropham concentrations in tubers under these typical conditions were below the recently revised levels that are acceptable for residues in both whole potatoes and peels. Also, in spite of lack of optimum conditions during the varied storage methods, chlorpropham treated tubers did not sprout.