Food Standards Australia New Zealand

20th Australian Total Diet Survey - Part B

Pesticides

Pesticides assist in food production by controlling pests and diseases. Even following good agricultural practices (GAP), residues of pesticides may still end up in the food we eat. However, food handling, storage and food processing, including preparation in the home, can reduce the levels of these residues.

The survey tested for the residues of a number of pesticides in a number of foods. A complete list of the pesticide residues for which foods in the survey were analysed can be found in Part 1 (Table 5) of the Supplementary Information (FSANZ 2002). The range of pesticide residues tested were:

  • chlorinated organic pesticides (organochlorines);
  • organophosphorus pesticides;
  • synthetic pyrethroid pesticides;
  • fungicides including chlorothalonil, dicloran, diphenylamine, procymidone and vinclozolin;
  • some carbamates; and
  • a range of other pesticides.

Chlorinated organic pesticides

Chlorinated organic pesticides (organochlorines) were among the first of the modern pesticides to be used in the 1940s. In general, they are highly stable compounds that persist in the environment, especially in soil and can concentrate in the food chain.

Due to their fat solubility, they are stored in the fatty tissue of humans and animals. The use of these organochlorines in developed countries has been heavily restricted since it was shown that some of these compounds were becoming an environmental hazard.

The ATDS pesticide tests examined food for a number of the organochlorine compounds and their metabolites. Metabolites include DDE and DDD, which are the metabolic products of DDT, and heptachlor epoxide, which is the metabolic product of heptachlor. The organochlorine pesticides aldrin, dieldrin, endrin, heptachlor, hexachlorobenzene, chlordane and DDT are no longer registered for use in Australia.

Organophosphorus pesticides

Organophosphorus pesticides are widely used insecticides with an array of chemical structures, properties and agricultural uses. Organophosphorus pesticides are mostly biodegradable and therefore do not concentrate in the food chain as is generally the case for organochlorine pesticides.

Organophosphorus pesticides act on the central nervous system of insects and animals, and in high doses are highly toxic. They inhibit the enzyme responsible for the metabolism of acetylcholine, which transmits signals between nerve cells and between nerve and muscle cells, and thus interfere with nervous system function. The hydrolysis of organophosphorus pesticides in biological systems generally yields less toxic substances, which are more readily excreted and tend not to accumulate in the human body. A list of the organophosphorus pesticides examined in the 20th ATDS can be found in Part 1 (Table 5) of the Supplementary Information (FSANZ 2002).

Carbamate pesticides

Like organophosphorus pesticides, carbamate pesticides are mostly biodegradable, and therefore do not concentrate in the food chain as is generally the case for organochlorine pesticides. They also act on the central nervous system of insects and animals, are highly acutely toxic, and tend not to accumulate in the human body.

The carbamate pesticides that were examined in the 20th ATDS are: aldicarb, carbaryl, fenoxycarb and pirimicarb.

Synthetic pyrethroid pesticides

Synthetic pyrethroid pesticides are man-made insecticides which have a similar chemical structure to natural pyrethrins found in chrysanthemums. Synthetic pyrethroids are fast-acting on the nervous system of insects. They are generally biodegradable and therefore tend not to persist in the environment.

The synthetic pyrethroid pesticides that were examined in the 20th ATDS are: bifenthrin, bioresmethrin, cyfluthrin, cyhalothrin, cypermethrin, deltamethrin, fenvalerate and esfenvalerate, flumethrin and permethrin.

754>Fungicides

Fungicides are used to control plant diseases caused by fungi. Fungicides can either be protectant or eradicant. Protectant fungicides protect plants from fungal infections and retard fungal growth before the fungi causes damage to the plants. Eradicant fungicides are used on plants that have already been invaded and damaged by fungal organisms.

The fungicides examined in the 20th ATDS were all protectant fungicides and included chlorothalonil, dicloran, diphenylamine, iprodione, procymidone and vinclozolin.

Results and dietary exposures to pesticides

Unlike metals and other substances, registered pesticides are either intentionally applied to crops to achieve a purpose or are not used, and therefore should not be present in food. For this reason, foods reported as containing ‘less than LOD’ for pesticide residues were assumed to contain no pesticide residues for the purposes of dietary exposure assessments. Even though certain organochlorine pesticides are no longer registered for use in Australia, for simplicity, their dietary exposures have been assessed in a similar manner to that used for other pesticide residues. There were no detections of the following organochlorine pesticide residues: aldrin, dieldrin, endrin, heptachlor, hexachlorobenzene and chlordane. DDT and/or its metabolites were detected in some foods at very low levels. Further details can be found in Table 20 of Part 3 of the Supplementary Information (FSANZ 2002).

The concentrations of pesticide residues reported in the surveyed foods are included in Part 3 of the Supplementary Information (FSANZ 2002), sorted by food (Table 19) and by pesticide (Table 20). Table 21 lists details of the LODs and LORs for the pesticide residues analysed.

Dietary exposures were estimated only when a pesticide was detected in a food. Some pesticides were not detected in any food and consequently their estimated dietary exposures were zero. These pesticides are tabulated in Appendix 3. Additionally, the foods that had no pesticide residue detections are listed in Appendix 4.

The estimated dietary exposures to pesticide residues for different age–gender groups are given in Figures 7 to 12 and in Appendix 2. All estimated dietary exposures to pesticide residues were below 16% of the respective ADIs and therefore all exposures are less than the applicable health standards. To simplify the figures, only dietary exposures greater than or equal to 0.2% of the ADI have been included. The detected pesticide residues for which dietary exposure for all age groups was less than 0.2% of the ADI were: acephate, azinphos methyl, bifenthrin, captan, chlorfenvinphos, chlorothalonil, total DDT [1] , dimethoate, endosulfan, fenoxycarb, fenthion, maldison, metalaxyl, methidathion, methoprene, o-phenylphenol, permethrin, pirimicarb, pirimiphos-methyl, propiconazole, pyrimethanil and tetradifon.

[1] Total DDT is the sum of p,p’ & o,p’ DDD, p,p’ & o,p’ DDE, and p,p’ & o,p’ DDT

Figure 7: Mean estimated dietary exposure to pesticide residues for adult males (25–34 years) as a percentage of the ADI , based on mean analytical results

20thATDS_figure7

(Note:   Only pesticide residues present at > 0.2% of the ADI are shown in the figure above)

Figure 8: Mean estimated dietary exposure to pesticide residues for adult females (25–34 years) as a percentage of the ADI, based on mean analytical results

20thATDS_figure8

(Note:   Only pesticide residues present at > 0.2% of the ADI are shown in the figure above)

Figure 9: Mean estimated dietary exposure to pesticide residues for boys (12 years) as a percentage of the ADI , based on mean analytical results

20thATDS_figure9

(Note:   Only pesticide residues present at > 0.2% of the ADI are shown in the figure above)

Figure 10: Mean estimated dietary exposure to pesticide residues for girls (12 years) as a percentage of the ADI, based on mean analytical results

20thATDS_figure10

(Note:   Only pesticide residues present at > 0.2% of the ADI are shown in the figure above)

Figure 11: Mean estimated dietary exposure to pesticide residues for toddlers (2 years) as a percentage of the ADI , based on mean analytical results

20thATDS_figure11

(Note:   Only pesticide residues present at > 0.2% of the ADI are shown in the figure above)

Figure 12: Mean estimated dietary exposure to pesticide residues for infants (9 months) as a percentage of the ADI , based on mean analytical results

20thATDS_figure12

(Note:   Only pesticide residues present at > 0.2% of the ADI are shown in the figure above)

Approximately 9% of all pesticides investigated had dietary exposures of greater than or equal to 0.2% of the ADI for all age-gender groups. For pesticides with estimated dietary exposures of less than 0.2% of the ADI for all age-gender categories, 65% had no detections in any food surveyed.

In general, the dietary exposure to pesticide residues was highest for the toddler age group. This is due to the high food consumption relative to body weight.

For adults (male and female), boys (aged 12 years) and girls (12 years), the highest dietary exposure to a pesticide residue, as compared to the ADI, was for methamidophos. Methamidophos is an organophosphorus insecticide. Methamidophos residues were detected only in tomatoes (refer to Tables 19 and 20 in the Supplementary Information for further details (FSANZ 2002)).

Vinclozolin

Residues of vinclozolin were detected in kiwifruit in the 20th ATDS. Vinclozolin is not registered for use on kiwifruit in Australia and theFood Standards Codedoes not include an MRL (the highest concentration of a chemical residue that is legally permitted or accepted in a food) for vinclozolin in kiwifruit. However, vinclozolin is permitted to be used on kiwifruit in New Zealand and it is possible that the kiwifruit containing vinclozolin residues were imported from New Zealand. The estimated dietary exposures to the residues of vinclozolin were below the reference health standard for vinclozolin.

If the kiwifruit containing the residues of vinclozolin were in fact imported from New Zealand, then it is legal for these kiwifruit to be imported and sold in Australia even though the residue concentrations were above the MRLs in theFood Standards Code. This is because, f ollowing the commencement of the Trans Tasman Mutual Recognition Arrangement on 1 May 1998:

  • food produced in Australia that complies with the MRLs in theFood Standards Codecan be legally sold in New Zealand; and
  • food produced in New Zealand that complies with theNew Zealand (Maximum Residue Limits of Agricultural Compounds)Mandatory Food Standard 1999can be legally sold in Australia.

The agreement between the Commonwealth of Australia and the Government of New Zealand to establish a system for the development of joint food standards (the Treaty) excluded MRLs for agricultural and veterinary chemicals in food. Australia and New Zealand independently and separately develop MRLs for agricultural and veterinary chemicals in food.

Comparison between the 19th ATDS and 20th ATDS results for pesticide residues

The differences between the dietary exposures to pesticide residues in the 20th ATDS and the 19th ATDS are not discussed because the small number of samples and the large range of foods in the food supply mean that it is difficult to draw definite conclusions.

Persistent organochlorine pesticide residues

DDT and/or its metabolites were detected in the 18th AMBS (0.11-0.19% of the ADI), 19th ATDS (0.04-0.50% of the ADI) and 20th ATDS (0.02-0.05% of the ADI).

Aldrin, chlordane and hexachlorobenzene were not detected in any sample in either the 18th, 19th or 20th surveys. Dieldrin, endrin and heptachlor were not detected in any sample in the 19th or 20th surveys. However, residues of both dieldrin and heptachlor were detected in the 18th ATDS at levels of 1.28-3.23% of the ADI and 0.02-0.05% of the ADI respectively. Endrin was not examined in the 18th ATDS.

Benzenehexachloride (BHC) – total residues were detected in both the 18th AMBS and the 19th ATDS but not in the 20th ATDS.

These figures indicate that the dietary exposure of Australians to persistent organochlorine pesticide residues is declining.

Recommendations for pesticide residue analyses

•   Pesticide residues should continue to be monitored to determine dietary exposure to pesticide residues. Over a number of surveys, a large amount of data relating to pesticide residues has been collected, with the estimated dietary exposures to pesticide residues being well below that of the respective health standards (ADIs). As a consequence, it is recommended that monitoring of pesticide residues be undertaken at a lower frequency in future surveys;

•   Monitoring of pesticide residues in future total diet surveys should focus on those for which there are no recent data and should not be limited to those chemicals registered for use in Australia.

Pesticide residues and metals in the infant diet

The infant-specific foods that were analysed in the 20th ATDS were mixed infant cereal, infant dessert, strained infant dinner and infant formula. These foods account for approximately 53% of energy intake in the constructed infant diet. No pesticide residues were detected in infant dessert, strained infant dinner and infant formula for the pesticides analysed. Residues of pirimiphos-methyl (an organophosphorus grain protectant) at levels close to the LOD were found in two of the nine analytical samples of mixed infant cereal. These results confirm that although infant foods contain pesticide residues, these are at very low levels.

The estimated dietary exposures to pesticides were generally higher in the toddler age category than in the infant age category. The contributing factors to this are: the solid portion of the infant diet is constructed by scaling down the patterns of consumption of a two-year-old child from the NNS; and pesticide residues were not detected in most of the infant specific foods.

In general, infants had a higher dietary exposure to metals (except for selenium and tin) than toddlers. Differences in body weight, levels of consumption of foods, or concentrations of metals may have contributed to the higher infant dietary exposures.