Monitoring pesticide and cadmium residues in fresh fruit and vegetables 1995-96 report
Introduction
The Sydney Markets survey commenced in 1989 for a three-year period as a joint project between the Sydney Market Authority and NSW Agriculture. The survey was extended in 1992–1995, with additional funding provided by the Horticultural Research and Development Corporation (HRDC). Reports for both these projects are available and detail the analyses performed, the range of chemicals tested and the different commodities sampled.
In 1995, a further application was made to HRDC for a continued three-year project, but this was reduced to a one-year project only. The 1995–96 survey focussed on the issue of ethylene bisdithiocarbamate (EBDC) fungicides which had been identified as an issue in the previous survey. The EBDC group represents one of the most commonly used fungicide groups on fruit and vegetables to control a wide range of plant diseases.
Due to the changes in funding, no cadmium samples were taken, but a number of herbicides were included for testing.
Summary of the 1995–96 survey
Some 554 samples comprising 35 different fresh fruit and vegetables were purchased from the Sydney Markets between October 1995 and October 1996 and analysed for the residues of 24 pesticides (not all samples were tested for all chemicals). Of the 554 samples, 359 were tested for most of the pesticides (including dithiocarbamates) and an additional 195 samples were tested only for dithiocarbamates.
Pesticide residues were either absent or complied with the Maximum Residue Limit (MRL) in 98.1% of samples. Only 7 samples (1.9%) contained a pesticide residue that exceeded the MRL (excluding dithiocarbamates).
MRLs for pesticides were exceeded in produce for three main reasons:
- incorrect use of pesticides on crops for which they were registered (4 samples)
- use of pesticides on crops for which they were not registered (2 samples)
- uptake of persistent organochlorine residues from the soil (1 sample).
The level of conformance with MRLs was similar to that for most countries where produce is routinely tested.
Residues of the ethylene bisdithiocarbamate (EBDC) fungicides were analysed for the survey year. Dithiocarbamates were detected in 197 samples (35.6%), and were suspected of exceeding the MRL in 9.0% of samples. (The precise violation rate is uncertain due to the existence of different MRLs for different chemicals on the same crop and an analytical test that cannot distinguish different parent dithiocarbamates. Further uncertainty relates to the existence of naturally occurring chemicals in some crops that have the potential to give false positives because the analytical technique is based on generation of carbon disulphide following acidification. In addition, the MRLs for dithiocarbamates are under review and this has a critical bearing on whether particular residues are interpreted as violative. Given these problems the significance of the findings is uncertain.)
MRLs for dithiocarbamates were consolidated and rationalized by the National Registration Authority (NRA) partly as a result of this residue monitoring program. These revised MRLs were gazetted by the NRA in April 1996 and these were incorporated into Standard A14 of the Australian Food Standards Code in December 1997.
Organochlorine pesticide detections have declined significantly over an eight-year period from 1989–1996 for all persistent OCs. This reflects the withdrawal of their use in 1987 and subsequent decline in residual activity in the soil. However, for endosulfan, a non-persistent OC, the detection level has remained consistent for the eight-year period.
No herbicide residues were detected in this survey.
The results of the survey indicate that the vast majority of growers use agrichemicals responsibly.
Table 1 Summary of results
| Sample Summary | Fruit | Vegetables | Total |
|---|---|---|---|
| Number of samples | 231 | 323 | 554 |
| Number of samples with no detections | 109 | 183 | 292 |
| Number of samples with residue detections | 122 | 150 | 272 |
| Residue Summary | |||
| Number of residues detected | 158 | 172 | 330 |
| Pesticide residue detections | |||
| Less than 50% of the MRL | 59 | 64 | 123 |
| More than 50% of the MRL, but less than the MRL | 3 | 1 | 4 |
| Above the MRL | 2 | 5 | 7 |
| Dithiocarbamate residue detections | |||
| Less than 50% of the MRL | 63 | 76 | 139 |
| More than 50% of the MRL, but less than the MRL | 1 | 6 | 7 |
| Above the MRL | 30 | 21 | 51 |
For the full report or more information please contact:
Delia Dray, Program Leader, Horticulture (Quality Assurance), or
Sandra Hardy, District Horticulturist (Fruit), Gosford.
