Survey of Chemicals in Imported Seafood - April 2008

​Prepared by the Imported Food Program


Executive Summary

The Australian Quarantine and Inspection Service (AQIS) tested 100 samples of seafood for residues of 88 agricultural and veterinary compounds. These samples were volunteered by importers and collected by AQIS between April 2006 and March 2007.

Residues of one or more antimicrobial chemicals were detected in 31 of the seafood samples tested. The levels were all low and posed no significant safety concerns.

The Australian government has committed to a review of the existing testing protocols for seafood imports and to further consider any measures necessary to improve the food safety standards of imported seafood products as part of the government’s plan for sustainable fisheries.

Background

AQIS undertakes testing of imported seafood at the rate of 5% of consignments to monitor compliance with the Australia New Zealand Food Standards Code (Food Standards Code). This testing program is in addition to testing for food classified as “risk” by Food Standards Australia New Zealand (FSANZ). The rates of inspection of risk food and for compliance monitoring are prescribed by the Imported Food Control Act 1992.

Testing of imported prawns for nitrofurans and chloramphenicol has been conducted since 2003. In 2005 AQIS introduced testing for malachite green as part of the routine sampling of imported aquaculture fish. In the 2006 calendar year, imported seafood tested for these antimicrobial compounds showed above 95% compliance with the Food Standards Code.

The testing of imported seafood for the above chemicals has been introduced following information from domestic findings, including a number of Australian surveys that detected antimicrobial chemicals, such as:

  • A 2005 FSANZ led national survey of chemical residues in aquaculture fish co-ordinated by FSANZ which tested for a range of veterinary residues such as nitrofurans, chloramphenicol, sulphonamides, tetracyclines, penicillins, macrolides, and quinolones, and also for polychlorinated biphenyls and a number of heavy metals. This survey found that residues of these veterinary chemicals in aquaculture fish were generally compliant with the Food Standards Code except for residues of malachite green and/or its metabolite leuco-malachite green in some domestically produced finfish and imported seafood.
  • A 2005 survey undertaken by South Australia which detected low levels of chloramphenicol in some imported crab meat.

In 2006 there were concerns that other chemicals may be present in seafood, particularly in farmed seafood and testing would need to be broadened to cover other chemicals. Of particular concern was the possible occurrence of veterinary compounds that are of critical importance in human medicine.

To investigate whether new chemicals needed to be added to the testing program, AQIS conducted a snapshot survey of antimicrobial and pesticide chemicals in imported seafood.

Method

A total of 100 samples were collected by AQIS officers. These samples were volunteered by the importer of the seafood and were collected aseptically by AQIS officers from the consignment being imported, using the sampling protocol given in Attachment 1. The samples were taken from imports at four points of entry into Australia (Sydney, Perth, Melbourne and Brisbane). The samples collected were of fish (excluding shark), crustacea (prawns and crab only) and eels. The seafood was chilled or frozen, cooked or uncooked and included both wild caught and farmed product. Canned, dried, battered or mixed seafood products were excluded from this survey.

There was no screening or targeting of these samples for specific country of origin or seafood species. The samples were primarily taken from consignments randomly referred to AQIS under the 5% random surveillance category.

An analyst appointed under the Imported Food Control Act 1992, Advanced Analytical Australia Pty Ltd, conducted the analysis of all samples. The testing was carried out using Liquid Chromatography Tandem Mass Spectrometry (LCMSMS) and extended Gas Chromatography Tandem Mass Spectrometry (GCMSMS). Each sample was tested against 88 agricultural and veterinary compounds which are listed in Tables 3 and 5.

AQIS acknowledges the support and co-operation of importers of seafood products that participated in this survey.

Results from the survey

Summary

  • No residues of the 49 agricultural pesticides were detected in the seafood samples.
  • Residues of one or more veterinary compounds were detected at quantifiable levels in 31 of the 100 seafood samples.
  • Residues of 13 veterinary compounds were detected in the 31 positive seafood samples. The residues detected belong to the sulphonamide, tetracycline, malachite green, penicillin, quinolone, fluoroquinolone and phenicol antimicrobial chemical groups.
  • The seafood products found to contain residues of veterinary compounds were from China, Indonesia, New Zealand, Thailand and Vietnam.
  • Of the 31 samples with detected residues, 9 were declared as farmed seafood, 14 samples were declared as wild caught and 8 did not declare the type of production.

Detailed results

The 100 samples were taken from seafood commodities as shown in Table 1 which also shows the detections by seafood commodity.

Table 1: Number of samples and detections by seafood commodity
Seafood commodity No. of samples No. of detections
Fish 53 16
Prawns 36 12
Crabs 9 2
Eels 2 1
Total 100 31

Table 2 shows the number of samples and detections of residues from each of the 15 countries of origin.

Table 2: Number of samples and detections by country
Country No. of samples No. of detections
Argentina 1 0
Canada 1 0
China 16 10
Denmark 1 0
Indonesia 30 10
Malaysia 2 0
Myanmar 3 0
New Zealand 13 6
Norway 1 0
Papua New Guinea 1 0
Saudi Arabia 2 0
South Africa 2 0
South Korea 2 0
Thailand 12 2
Vietnam 13 3

Table 3 shows the testing results against the 49 agricultural (pesticide) chemicals.

Table 3: Results against agricultural compounds
Chemical No. of detections
Acephate 0
Aldrin 0
Azinphos-ethyl 0
Azinphos-methyl 0
BHC (alpha, beta, delta, gamma) 0
Bromophos-ethyl 0
Carbaryl 0
Carbophenothion 0
Chlordane 0
Chlorpyrifos 0
Chlorpyrifos-methyl 0
Chlorfenvinphos (cis & tran) 0
DDD 0
DDE 0
DDT 0
Demeton-S-methyl 0
Diazinon 0
Dichlorvos 0
Dicofol 0
Dieldrin 0
Dimethoate 0
Disulfoton 0
Endosulfan (alpha & beta) 0
Endosulfan sulphate 0
Ethoprofos 0
Ethion 0
Fenamiphos 0
Fenitrothion 0
Fenthion 0
Fipronil 0
Hexachlorobenzene 0
Heptachlor 0
Heptachlor epoxide 0
Malathion 0
Methacrifos 0
Methamidophos 0
Methidathion 0
Mevinphos 0
Monocrotophos 0
Omethoate 0
Parathion 0
Parathion-methyl 0
Phorate 0
Phosmet 0
Pirimicarb 0
Pirimiphos-methyl 0
Procymidone 0
Prothiofos 0
Vamidathion 0

Table 4 shows detections in each of the four seafood commodities of residues against broad veterinary compound group.

Table 4: Number of detections against veterinary compound class/seafood commodity
  Sulphonamides Tetracyclines Malachite
green
Penicillin Quinolones Fluoro-
quinolones
Phenicols
Fish - 2 1 11 2 - -
Crabs - 1 - 1 - - -
Eels 1 - - - - - -
Prawns 4 4 - - 4 1 1
Total 5 7 1 12 6 1 1

NOTE: some seafood samples contained more than one compound thus the total number of residues detected exceeds the number of samples with detections.

Table 5 identifies detections of specific chemicals. Shaded cells identify the individual antimicrobial compounds detected.

Table 5: Number of detections of veterinary compounds (antimicrobial chemical)
Group Chemical No. of
tests
No. of
detections
Chemical No. of
tests
No. of
detections
Malachite green Malachite green 100 1 Leucomalachite green 100 0
Quinolones Flumequine 100 6 Oxolinic Acid 100 0
Phenicols Florfenicol 100 1 Thiamphenicol 100 0
Macrolides Tylosin 100 0 Erythromycin 100 0
Fluoro-quinolones Ciprofloxacin 100 1 Ofloxacin 100 0
Enrofloxacin 100 2 Gatifloxacin 100 0
Levofloxacin 100 0 Moxifloxacin 100 0
Sarafloxacin 100 0 Norfloxacin 100 0
Tetracyclines Chlortetracycline 100 0 Tetracycline 100 0
Doxycycline 100 0 Oxytetracycline 100 7
Sulphonamides Sulphamerazine 100 0 Sulphamethoxazole 100 5
Sulphadimethoxine 100 1 Sulphamethoxypyridazine 100 1
Sulphachlorpyridazine 100 0 Sulphapyridine 100 0
Sulphadiazine 100 0 Sulphaquinoxaline 100 0
Sulphadoxine 100 0 Sulphathiazole 100 0
Sulphamethazine 100 1 Sulphatroxazole 100 0
Sulphameter 100 1 Sulphisoxazole 100 0
Penicillin Ampicillin 100 3 Benzyl penicillin 100 0
Amoxycillin 100 11 Cloxacillin 100 0
Other Trimethoprim 100 0      

NOTE: some seafood samples contained more than one compound thus the total number of residues detected exceeds the number of samples with detections.

Table 6 shows the breakdown of detections against commodity and country. Shaded cells identify commodities where residues were detected.

Table 6: Number of samples and detections by country
Country Commodity No. of
samples
No. of
detections
Argentina Fish 1 0
Canada Prawns 1 0
China Fish 1 0
Prawns 14 9
Eel 1 1
Denmark Prawns 1 0
Indonesia Fish 25 7
Prawns 1 1
Crab 4 2
Malaysia Prawns 2 0
Myanmar Prawns 3 0
New Zealand Fish 12 6
Eel 1 0
Norway Fish 1 0
Papua New Guinea Prawns 1 0
Saudi Arabia Prawns 2 0
South Africa Fish 2 0
South Korea Fish 2 0
Thailand Fish 2 0
Prawns 9 2
Crab 1 0
Vietnam Fish 7 2
Prawns 3 1
Crab 3 0
Total   100 31

Tables 7 and 8 detail the levels of residues detected against commodity and country.

Table 7: Levels fo antimicrobial residues detected by seafood commodity and country (Note 1?g/kg = 0.000001 grams/kg = 1 part per billion
Country Product Sulphonamide Tetracyclines Malchite green
µg/kg
Penicillin Quinolones / Fluoroquinolones Phenicols
Sulpha-
methoxazole
µg/kg
Oxytetracycline
µg/kg
Amoxycillin
µg/kg
Ampicillin
µg/kg
Flumequine
µg/kg
Ciprofloxacin
µg/kg
Enrofloxacin
µg/kg
Florfenicol
µg/kg
China1 Fish - - - - - - - - -
Prawns 2.3-5.4 8.6 - - - 2.6-17 3.1 33-130 11
Indonesia Fish - 2.0 - 14-130 - 2.0 - - -
Prawns - 3.4 - - - - - - -
Crab - 6.7 - 380 -   - - -
New Zealand Fish - - - 25-71 10-130 - - - -
Thailand Prawns - 2.1 - - - 3.4 - - -
Vietnam Fish - 5.9 7.8 - - 8.2 - - -
Prawns - 2.0 - - - - - - -

1 one eel sample was detected with a range of residues from several chemicals from the sulphonamide antimicrobial group. The results for this sample are detailed in Table 8

Table 8: Levels of sulphonamide residues detected in one eel sample from China
  Sulphadimethoxine
µg/kg
Sulphamethazine (Sulfadimidine)
µg/kg
Sulphameter
µg/kg
Sulphamethoxazole
µg/kg
Sulphamethoxypyridazine
µg/kg
Eel - China 3.4 8.6 12 - 12

The results of the survey were reviewed by FSANZ and the National Health and Medical Research Council (NHMRC) to provide advice on the public health and safety risks associated with the detected residues. The NHMRC sought advice on antimicrobial resistance from its Expert Advisory Group on Antimicrobial Resistance (EAGAR).

FSANZ safety assessment

Based on dietary modelling, the FSANZ assessment did not identify any major safety concerns associated with the low levels of antimicrobial residues detected. On these grounds, the residues do not constitute a medium to high risk to public health and safety. The full FSANZ report is available as a separate document on the AQIS website.

The dietary exposure assessment involved comparing estimated dietary exposures with the established reference health standard for each chemical. Based on this assessment for each chemical and a worst case scenario, the quantities of a particular seafood that would need to be consumed before reaching levels near the reference health standard are generally very large. In the majority of cases, the limit is not reached unless hundreds and sometimes thousands of kilograms of a particular seafood are consumed each day over a lifetime. The estimates of seafood consumption required to exceed the Acceptable Daily Intake (ADI) for a range of chemicals are listed in Table 9.

EAGAR assessment of antimicrobial resistance

EAGAR noted that the presence of antimicrobial compounds was of concern for all sources of farmed seafood, including domestically produced product. EAGAR expressed concerns particularly about the presence of fluoroquinolone (flumequine, ciprofloxacin and enrofloxacin) residues, which were found predominantly in prawns. EAGAR considers that any development of resistance to fluoroquinolones would constitute a high risk to their efficacy in clinical medicine.

Table 9: Seafood consumption required to exceed the ADI for the chemicals detected
Chemical Commodity Maximum
detected
concentration
µg/kg
ADI
(mg/kg bw)
Approximate
consumption amounts
required to exceed ADI
(kg/day)
Sulphamethazine Eel 8.6 0.02 155
Sulphadimethoxine Eel 3.4 0.20 3,941
Sulphamethoxy-pyridazine Eel 12 0.20 1,116
Sulphameter Eel 12 0.10 558
Sulphamethoxazole Fish (NFS) 5.0 0.20 2,680
Prawns 5.4 0.20 2,481
Oxytetracycline Crab 6.7 0.03 300
Garfish 2.0 0.03 1,005
Prawn 8.6 0.03 233
Climbing Perch 5.9 0.03 340
Amoxicyllin Barramundi 35 0.20 382
Crab 380 0.20 35
Fish (NFS) 58 0.2 231
Hairtail 130 0.20 103
Ling 71 0.20 188
Swordfish 51 0.20 262
Ampicillin Orange Roughy 10 0.20 1,340
Ling 16 0.20 837
Swordfish 130 0.20 103
Flumequine Mackerel 2.0 0.03 1,005
Prawns 17 0.03 118
Spanish Mackerel 8.2 0.03 245
Ciprofloxacin Prawn 3.1 0.002 43
Enrofloxacin Fish (NFS) 33 0.002 4
Prawns 130 0.002 1
Florfenicol Prawns 11 0.001 6

Notes: No other background exposure from other foods considered.
(NFS) = not further specified
Mean body weight of 67kg used for Australians aged 2 years and above.

This table is an extract from the formal advice provided to AQIS by FSANZ. The Acceptable Daily Intake (ADI) levels as used in the above table are explained in that formal advice.

Discussion of the survey results

Imported seafood has been found to contain residues of some veterinary compounds that do not currently have a Maximum Residue Limit (MRL – see Appendix A) in the Food Standards Code. As such, this seafood is not compliant with Australian food standards.

There is no significant safety concern with the detected residues as the levels are low. In the majority of cases, the quantities of seafood that would need to be consumed before reaching levels of exposure near the acceptable daily intake are in the hundreds of kilograms.

EAGAR has concern about the presence of residues of antimicrobial compounds of significance in human medicine, in particular the fluoroquinolone compounds.

The Australian government has committed to a review of the existing testing protocols for seafood imports and to further consider any measures necessary to improve the food safety standards of imported seafood products as part of the government’s plan for sustainable fisheries. This review will be completed by the end of 2008.


Appendix A - MRLs for veterinary compounds

An MRL is the highest concentration of a residue of a particular chemical that is legally permitted or accepted in a food or animal feed. The concentration is expressed in milligrams of the chemical residue per kilogram (mg/kg) of the commodity. MRLs are regulatory standards which help to monitor that the chemical product has been used as directed on the approved label. If an MRL is exceeded, it usually indicates a misuse of the chemical but does not normally indicate a public health or safety concern.

The Food Standards Code includes the permitted MRLs for agricultural and veterinary chemicals in food for sale in Australia. As some antimicrobials are not permitted for agricultural use in Australia, no detectable residues are permitted under the Food Standards Code.

Therefore, the detections of such chemical residues in this survey for various seafoods indicates that those seafoods are non-compliant with the Food Standards Code.

As identified in Table 10, the levels of residues detected in some of the imported seafood samples would not constitute compliance breaches in the country of production or in other export destinations; that is, residues in seafood at these levels has been assessed as safe by regulators in those countries. The Codex Alimentarius Commission has also established MRLs for some of these veterinary compounds in food producing animals, including one for oxytetracycline in prawn muscle. In most cases, MRLs have been established in edible tissues of food producing animals at levels that are much higher than observed in the current survey of seafood.

Table 10: Comparison of detected residue levels with Maximum Residue Limits (MRLs) for other countries
  Sulphonamide Tetra-cycline Malachite green
µg/kg
Penicillin Quinolones / Fluoro-quinolones Phenicols
  Sulphadi-methoxine
µg/kg
Sulphamethazine (Sulfadimidine)
µg/kg
Sulpha-meter
µg/kg
Sulpha-methoxazole
µg/kg
Sulphameth-oxypyridazine
µg/kg
Oxy-tetracycline
µg/kg
Amoxycillin
µg/kg
Ampicillin
µg/kg
Flumequine
µg/kg
Cipro-floxacin
µg/kg
Enro-floxacin
µg/kg
Flor-fenicol
µg/kg
AQIS Survey detections 3.4 8.6 12 2.3-5.4 12 2.0-8.6 7.8 14-380 10-130 2.0-17 3.1 33-130 11
EU MRL 100 100 100 100 100 100   50 50 600 (fin fish) 200 (all other food producing species) 100 100 1000 (fin fish only) 100 (all other food producing species)
US MRL           2000             2000 (catfish only)
Codex MRL           200       500 (trout)      
No. samples failed Australian MRL 1 1 1 5 1 7 1 11 3 6 1 2 1
No. samples that exceeded the highest of NZ*, EU, US or Codex MRLs 0 0 0 0 0 0 1 3 1 0 0 1 0

* New Zealand has a default MRL of 100 ug/kg where the specific food/residue combination has not been assessed. However, the default MRL does not override the prohibition in the Food Act on the sale of food that is unfit for human.


Attachment 1 - Sampling Protocol

All sampling for the survey is to occur when the Imported Food inspection is undertaken.

Please conduct normal inspection activities, including sampling. At the end of the inspection activities, please take an additional sample.

General notes

  • Sample quantity: 500 grams
  • Sample portion: the edible portion
  • Sample preparation: samples are to be tested “as is” – that is, fish fillets or marinade fish etc must not be washed or rinsed or otherwise treated prior to testing.

Drawing the samples

  1. Obtain permission to draw a sample
  2. Ensure that conditions are suitable for sampling – aseptic sampling is required
  3. Collect sample and place into the appropriate container
  4. Seal sample container
  5. Clean equipment
  6. Continue until all sub-samples have been sampled
  7. Place all sub-samples into an IFP tamper evident bag, and attach a completed ‘Sample Identification Form’ to the bag
  8. Deliver sample to laboratory sample depot for laboratory pick up
  9. Keep all samples frozen including where the product had only been chilled
  10. Notify laboratory to arrange for collection of sample.
Last reviewed: 4 November 2019
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