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Produce Safety in New Zealand

The following are research and outbreak reports previously published by NZFSA, MAF, MoH and their affiliates.

 An outbreak of hepatitis A associated with consumption of raw blueberries (Auckland District Health Board, 2002)
The mode of contamination for the hepatitis A outbreak (2001) could not be defined but was likely due to poor picker hygiene or faecally contaminated groundwater. Recommendations from the outbreak report emphasized the need for HACCP-based food safety programmes, handwashing with adequate volumes of water, antibacterial soaps or alcohol-based gels, and adequate illness exclusion policies.

Investigation of a Salmonella Saintpaul outbreak in the Auckland and Waikato regions (Auckland Regional Public Health Service, 2006)
The mode of contamination for the Salmonella outbreak (2005) was not conclusively identified. However, rinsing the carrots with stream water that was contaminated with E. coli and considered unsuitable for drinking was noted as a likely, although not exclusive, source of the contamination. The outbreak report recommends review of water quality standards for produce processing and label of raw produce to indicate the need for further washing and peeling by the consumer prior to consumption.

Food safety and hydroponically cultivated vegetables (ESR 1999)
Three categories of hydroponically grown ready-to-eat vegetables (leafy vegetable, sprouts and herbs) from throughout New Zealand were tested for the presence of pathogens and indicator organisms and producers surveyed for production procedures. Pathogens were not found in any samples but Escherichia coli was isolated from 12.8 % of sprouts, 14% of leafy vegetables and 5% of herbs, indicating a potential small and variable risk of the hydroponically grown vegetables harbouring a pathogen. The report recommends seed disinfection and implementation of HACCP based food safety programmes to minimise the risk of contamination.

Generic HACCP models for food assurance programmes [fresh fruit and vegetables] (AgriQuality New Zealand, Dec 2001)
Generic HACCP Models have been developed for a range of fresh produce using information obtained from a literature search in conjunction with analysis of some specific production systems operating in New Zealand. Although the literature search was extensive there are still gaps in our knowledge with respect to food safety risks in the produce industry and acceptable limits for hazards. Acceptable limits have been described as the HACCP plan’s food safety objectives, and suitable controls for hazards identified. The danger of implementing and maintaining impractical unnecessary control measures has been highlighted. Techniques to verify the adequacy of the controls together with supporting documentation are described.

• International literature Search and HACCP Models Report, (AgriQuality New Zealand, Aug 2001)

• Implementation Guide (AgriQuality New Zealand, Sept 2001)

Microbiological & heavy metal contamination of watercress in the Wellington region (Victoria University, 2001)
Watercress is a popular food, increasingly consumed raw either in salads or as a garnish. Watercress is potentially subject to heavy metal and microbiological contamination from the water/sediment it grows in. Representative streams in the Wellington and Wairarapa regions showed variable but significant levels of E. coli in both the watercress and water samples (well above freshwater recreational guidelines). Campylobacter was detected in the growing waters at all sites (80% of the samples) and in 11% of the watercress samples. Except for zinc on one occasion, heavy metal levels in watercress did not exceed the NZ Food Regulations (1984) at any of the sites. The report recommends that watercress harvested from uncontrolled surface water sources should be cooked, and only eaten raw if from strictly controlled and adequately monitored growing waters.

Risks associated with bacterial pathogens in exported fruit and vegetables (ESR, 2002)
This qualitative risk assessment and ranking for microbiological hazards in conventional and organic fresh produce exported from New Zealand identifies Escherichia coli O157:H7 and lettuces, and Salmonella and apples, or tomatoes, as the hazard food combinations of choice to survey given the risk the pathogen poses to human health in New Zealand, the likelihood of the pathogen occurring on a product, and the export value of the produce product.

Levels of Escherichia coli O157 in lettuces and Salmonella in apples (ESR, 2003)
E. coli O157:H7 was not detected on 240 conventionally grown and 234 organically grown lettuces (several varieties) from multiple nationwide growers. All 239 apples (eight varieties) grown under the Integrated Fruit Production programme (IFP) tested negative for Salmonella. In contrast, of 230 organic apples tested, only a single batch of 5 samples from a single orchard tested positive for Salmonella Typhimurium DT12a, albeit at very low concentration. Nevertheless, the report concludes that the introduction and effective implementation of HACCP based food control programmes in the edible fruit and plant product industries has been beneficial.

Shiga-toxin producing Escherichia coli in leafy vegetables (ESR, 2006)
Shiga-toxin producing Escherichia coli (STEC) infection, in particular that of E. coli O157:H7, may result in serious illness in children. A recent nationwide outbreak in the USA was caused by contaminated spinach. Fortunately, there is little indication of foodborne transmission in New Zealand, and none implicating leafy vegetables. Two surveys totaling ~600 samples of mostly lettuce and spinach have failed to detect E. coli O157:H7. Horticultural practices only allowing the use of fully composited faecal waste minimizes the risk of STEC infection from leafy vegetables.

Listeria monocytogenes in ready to eat RTE salads (ESR, 2005)
Listeria monocytogenes infections are rare in New Zealand at less than 20 per year, although are usually serious. Listeria is ubiquitous in the environment and while most people ingest small numbers daily without subsequent illness, at-risk groups of the population may become ill. Foods with long shelf lives that are stored under refrigeration are usually associated with Listeria because, unlike other pathogens, they can grow at refrigeration temperatures. Nevertheless, there is little indication that L. monocytogenes infection in New Zealand is associated with ready-to-eat salads without dressings (lettuce and cabbage based salads, and excludes coleslaws or salads with non-vegetable ingredients). Data on the prevalence of L. monocytogenes in New Zealand ready-to-eat salads are limited. Nevertheless, application of Good Agricultural Practice (GAP) during growth of the vegetables, and risk management measures including Food Safety Programmes and testing for L. monocytogenes by processors ensure that the risk in New Zealand is minimised.

Discussion document on pathogens in fruits and vegetables in New Zealand (ESR, 2007)
A discussion document from ESR (due June 2007) will be a compilation of the above reports and incorporate all current knowledge from New Zealand, and that from overseas that is relevant to New Zealand. It will include discussion of industry Codes of Practice and comments on relative exposure to consumers for pathogens in vegetables and fruits, and on relative risk, if able to be deduced. The document will comment on data gaps.

 Microbiological Quality of Imported Fruits and Vegetables
Overseas, outbreaks of foodborne illness associated with the consumption of pathogen-contaminated fresh produce from growing areas with poor water and fertilizer quality, questionable worker hygiene programmes and/or a lack of effective decontamination practices are on the increase. Fortunately, in New Zealand, such poor practices are uncommon and hence cases of foodborne illness associated with produce are rare. Nevertheless, consumption of raw minimally processed produce. While New Zealand GAP and food safety programmes have been enhanced to minimize the risk from domestically grown fresh produce, the risk from imported produce remains unknown although NZFSA notes that there is no evidence of problems associated with fresh produce imported into New Zealand. Nevertheless, NZFSA is initiating a microbiological survey of imported produce to be carried out in 2008. 

Australian Studies

Horticultural products imported into Australia could equally be imported directly into New Zealand or via Australia under the Australia-New Zealand free trade agreement.

The Australian Quarantine and Inspection Service (AQIS) recently carried out two "snapshot" microbiological and chemical surveys of imported fresh vegetables. Generic E. coli, an indicator of faecal contamination, was detected in 14 of 97 products tested in the first survey. Nevertheless, Salmonella was not detected in any of the 97 products, nor E. coli O157:H7 (pathogenic type) in a subsequent survey of 41 product types that had previously tested positive for generic E. coli. Two samples from the first survey returned positive chemical residue tests: one less than the Food Standards Code (FSC) MRL; the other (fenvalerate in garlic) not having a standard under the FSC or CODEX but nevertheless detected at a concentration that is not considered to constitute a risk to human health.

Similarly, the Western Australia Department of Public Health in 2005 tested 151 imported fruits and vegetables for compliance with FSANZ guidelines for ready-to-eat foods. Despite 1.4% exceeding guidelines for Bacillus cereus and generic E. coli (not different to that of domestically grown produce), none were considered hazardous and all products tested negative for Campylobacter, E. coli O157:H7 and were within guidelines for Staphylococcus aureus and Listeria.

Food Standards Australia New Zealand (FSANZ) has concluded that the results confirm that imported horticultural products pose a low health risk.