Persistence, transformation and fate of CIPC in commercial potato stores
CIPC was widely used by the potato industry as a sprout suppressant on crops in storage. It was applied periodically as a fog into both bulk and box stores. CIPC permeated the fabric of the store and, unfortunately, routine cleaning of a store did not remove the residues entirely. Cross contamination of commodities with CIPC, from the store fabric, has been reported previously. Cross-contamination is a problem when commodities other than potatoes are stored as the Maximum Residue Level (MRL) for CIPC on these is the Limit of Quantification (usually 0.01 or 0.02 mg/kg). At the time of writing the MRL for CIPC on potatoes is 10mg/kg, but this value is likely to be reduced following the chemical’s non-renewal. Growers and store managers will need to take care to ensure cleaning practices are sufficient to keep contamination levels below any future (temporary) MRL.
This page was last updated in December 2021. Refer to the Health and Safety Executive, Chemicals Regulation Division (CRD) website for more detailed, up-to-date information on MRLs.
This PhD studentship determined the extent of CIPC contamination found in stores, and studied the equilibrium, kinetic and thermodynamic processes involved in CIPC adsorption within building materials. In addition, a quantitative analytical method was developed for trace level CIPC analysis in a range of complex matrices including building materials such as concrete and wood and fresh commodities such as grain, fresh vegetables and seed potatoes. Alongside this, the route of and degree of cross-contamination of CIPC on commodities was investigated, together with the breakdown of CIPC under store conditions which allowed appropriate decontamination strategies to be developed.
Persistence and distribution of CIPC and 3-chloroaniline (3-CA) contamination in potato stores was quantified for the first time, improving our understanding of the behaviour of these chemicals. The developed methods successfully demonstrated the persistence of CIPC and 3-CA in the concrete flooring of commercial potato stores. Depth distribution studies confirmed that concrete was pervious to CIPC and the degree of penetration may have been dependent on the physical nature of the concrete.
This study showed the majority of CIPC residues were found within the top one centimetre of concrete, providing an indication on the depth of concrete that would require removal or treatment to allow stores to be re-used. The study also demonstrated that risk assessments based on the concentration of CIPC in concrete from a single location in a store would be prone to inaccuracies because levels are heterogeneous.
It was concluded that storage of grain (and other food or feed commodities with an MRL set at the limit of quantification) is at significant risk of cross contamination and exceedance of the MRL when stored in buildings with a history of CIPC use.. Due to the longevity of the chemical residues and the widespread contaminant distribution within the store environment, no ‘decontamination strategy’ recommendation could be made at this stage.