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Grain results
Discussion: grains results
The grain random monitoring project covered 20 commodities, with 3 435 samples collected and subjected to analysis. Wheat grain and its products (bran and flour) contributed the largest number of samples. There were 19 residues of agricultural chemicals detected above Australian Standards (maximum residue limit [MRL] and extraneous residue limit [ERL]). Of these, only three contraventions occurred in export grain.
Pesticides
A range of pesticides is used either in-crop or for post-harvest grain protection. A multi-residue screen is used to detect residues of such chemicals registered for use in Australia, as well as some chemicals of concern to industry that are registered in overseas markets for use on grains. The principal groups of pesticides covered are organophosphate insecticides, synthetic pyrethroid insecticides, carbamate insecticides, insect growth regulators, other insecticides and some fungicides. The pesticide screen was conducted on all 3 435 grain samples.
In export grains, there were three samples from export containers that did not comply with relevant Australian Standards. These residue contraventions were detections of the fungicide triadimefon in lentil (one), the synthetic pyrethroid phenothrin in barley (one), and the herbicide simazine in wheat grain (one). The traceback investigation for lentil was inconclusive, and the other two tracebacks have not been finalised as this report goes to print. However, it is suspected that the phenothrin/barley residue was a sample contamination rather than a residue in the commodity.
All but 16 domestic samples complied with ANZFSC. Of these, one violation occurred in the milled products sub-project and 15 in the domestic market sub-project.
There were two instances of sample contamination in sorghum and barley that were found to contain the household insecticide bioresmethrin. These samples came from a feedlot, and information from the sample collector indicated that the sampling equipment had been treated with a common fly spray. Another residue contravention in barley by the insecticide indoxacarb was also discovered in a feedlot, but the traceback is not complete at the time of printing this report.
In the oilseeds project, there were three residue detections of the insecticides carbaryl and three residue detections of chlorpyrifos-methyl, all found in canola delivered to an oilseed crusher from the same supplier. The source of contamination is unknown, but is likely to be from a storage bin that had previously been sprayed with these two compounds. Additionally, there were two detections of pesticides in canola. One triadimefon residue and one organochlorine residue were found in samples of canola delivered to an oilseed crusher. The triadimefon residue was found to be a cross-contamination: fertiliser previously treated with triadimefon had been passed through an auger, and then the canola was elevated through the same auger to storage without the equipment being cleaned. The producer is changing management practices in response to the traceback. The organochlorine residue had almost certainly arisen from an environmental contamination, possibly from the on-farm bulk storage shed.
The only sample of mung bean was found to contain the pesticide dichlorvos. Investigations revealed that the shed where the mung bean was stored had been treated with dichlorvos, and cross-contamination had occurred.
Three residues of the fungicide flutriafol were found in wheat grain delivered to stockfeed manufacturers. The exact reasons for these contaminations are unclear, but the most likely source of the residue is inappropriate on-farm practice, or seed dressing that came into contact with other grain.
One milled grain sample (wheat bran) contained a fenitrothion residue above the appropriate Australian Standard. The corresponding wheat and flour samples did not contain residues in excess of the MRL; therefore, the whole grain had been treated appropriately. When milled, any residue present in the grain as a whole (however small) tends to be retained in the bran fraction, and in this case that retention was in excess of the bran MRL.
Fumigants
During the reporting period, 96 grain samples were selected at random by the multi-residue screen-testing laboratory and forwarded to a phosphine testing laboratory to determine total phosphine residues. Any residues detected that are equal to or above 0.002 mg/kg initiate further analysis of the sample to determine the component of the residue due to unreacted phosphide and/or absorbed phosphine. There were no detections of phosphine residues above the action level of 0.002 mg/kg.
Organochlorines
This test covers a range of chemicals that were once widely used in agriculture and are known to persist in the environment. In addition to detecting these older organochlorine pesticides, the test method also covers endosulfan, a relatively non-persistent organochlorine registered for broadacre agricultural uses. As mentioned above, there was one low-level detection of an organochlorine in canola which may have arisen from an environmental contamination.
Environmental contaminants
Tests for three environmental metal contaminants (cadmium, lead and mercury) were conducted on 297 samples. There were no detections of environmental contaminants above Australian maximum limits (MLs) in any grain sample tested.
Results for the grains products (in alphabetical order by commodity name) are shown in the tables that begin on page 112. The heading 'LOR' in the tables refers to the limit of reporting: this is the minimum concentration (mg/kg) of a residue used for reporting purposes. Results of analyses lower than the LOR are not included in this report. Typically, the LOR set by NRS is 10–20% of the respective MRL/ERL or ML.
09 Dec 2009