Thursday, 19 September 2019
For the past 50 years or so, sprout suppression in the UK has relied on chlorpropham (CIPC). One of the problematic aspects of the sprout suppressant is that application leaves behind residues for many years after it has been applied. A recent AHDB-funded PhD project investigated the fate of CIPC in UK stores, to shed some light on its persistence and distribution, as well as to inform future decontamination strategies.
Circulation system a key factor
Commercial and research potato stores with differences in the historical use of CIPC were tested for the presence of residue in their concrete flooring. This study showed that concrete is pervious to CIPC, meaning that it allows the sprout suppressant to pass through it, and that most of it is found in the top one centimetre of concrete. Traces of the active and its metabolite 3-chloroaniline (3-CA), were found in all stores, regardless of the quantities of CIPC applied and how long it was applied for. This included commercial stores that had received their last CIPC application up to 25 years ago. The research project also demonstrated that the distribution of CIPC residues within a store is heterogeneous and is largely influenced by the type of air circulation system used to distribute the sprout suppressant in a store. Larger quantities of CIPC were found in areas closest to the point of entry of CIPC application. Another part of this PhD project focused on quantifying cross contamination of grains in commercial potato stores previously treated with CIPC. Residues of the sprout suppressant were found, revealing that cross contamination is possible. Dust particles and store headspace were both found to be major routes of contamination.
The outcomes of this PhD project have significantly progressed the industry’s knowledge of how CIPC behaves in potato stores and what sort of decontamination strategies could realistically be put in place. Building on these findings, Sutton Bridge Crop Storage Research is undertaking further experimental work to determine CIPC residue concentration levels in a range of different stores. With the MRL set to change to the limit of quantification once CIPC is withdrawn for use, this data will provide a valuable source of information as to what the industry can realistically achieve in terms of MRL. This evidence will form part of a wider dataset generated by a European consortium of industry and research partners who have come together to inform regulators.
The PhD project ‘Persistence, Transformation and Fate of CIPC’ was undertaken by Dr Leisa Douglas, and was a collaboration between SUERC (Scottish Universities Environmental Research Centre) and Sutton Bridge Crop Storage Research.