High resolution GC with effluent splitting to ECD and NPD allowed detection of over 80 pesticides. The large peak on both channels is the internal standard carbophenothion. Most of the MRL violations were from moderate residues due to unregistered uses of a pesticide approved for other crops rather than uses of banned products or levels exceeding set MRLs. The results were in broad agreement with residue monitoring in other countries and confirmed Department of Health ranking's which put microbial contamination of food as a much more serious health problem than residues. Most pesticides lack systemic action and therefore residues are mainly on the exterior surfaces where they are amenable to removal in operations such as trimming, washing or peeling that most crops undergo before consumption.
Further losses can arise during cooking.
While environmental and dietary concerns are of increasing importance to pesticide policy, the issue of residues in our export agricultural products continues to dominate thinking in the agricultural sector. Meeting quarantine and MRL standards while producing blemish free fruit can be a difficult exercise for growers, particularly as requirements vary between countries. Producer boards setting recommended spray programmes for growers need good insight into the residual properties of the pesticides. The initial quantity of pesticide deposited, D o , is determined by the rate of application and size of the fruit. The first exponential term accommodates initial rapid volatilisation of pesticide while the second term covers slower losses of more firmly retained residues.