5. Regulation and trade

5.1 Introduction
5.2 Impact of L. monocytogenes on trade
5.3 Microbiological criteria
5.4 Recommendations for establishing criteria

5.1 Introduction

The rules that govern international trade are those agreed on during the Uruguay Round of Multilateral Trade negotiations and apply to Members of the WTO. With respect to food safety matters, those rules are set out in the SPS Agreement. The overall objective of the SPS Agreement is to permit Member Countries to take legitimate measures to protect the life and health of their consumers. Sanitary and phytosanitary measures shall not be applied in a manner that would constitute a disguised restriction on international trade.

The SPS Agreement establishes a two-tier test of whether a country’s regulation of a food safety issue, such as L. monocytogenes contamination of fishery products, is legitimate or is an illegitimate non-tariff trade barrier. The sequence of evaluation for an SPS regulatory measure under the WTO progresses from a science to a policy level test. The questions asked are:

Is the SPS measure based on an internationally accepted standard?

Failing this, has the country supplied a valid risk assessment to defend its selection of the regulatory measure?

Finally, are there alternative methods of implementation that have a lesser trade effect while achieving the same level of protection ?

The ordering of the two levels is important, as a risk assessment (science level) needs to lead any policy discussion and selection among risk management and communication strategies. The SPS Agreement encourages harmonization through adoption by countries of internationally recognized standards. In addition, the agreement requires that a country accepts the sanitary and phytosanitary measures of another country as equivalent, even when they differ from their own, if the exporting country objectively demonstrates that its measures achieves the importing countries appropriate level of protection.

International trade of fishery products undergoes verification of a safety assurance system and/or port-of-entry inspection. In the case of listeriosis prevention, like for other food safety hazards, it is well recognized that implementation of safety assurance such as Good Hygiene Practices (GHP) and HACCP systems are the most efficient and reliable approaches to ensure safety. However, if records demonstrating the application of HACCP-based safety systems are not available, the alternative is inspection at the port-of-entry.

Differences in criteria and policies among countries stress the urgent need for harmonization of the criteria, including sampling plans, sample size, and methodology. In this respect, the CAC encourages harmonization of food standards based on risk assessment. For example, the "Recommended International Code of Practice-General Principles of Food Hygiene", includes provisions for GHP and for the incorporation of HACCP or other equivalent food safety assurance systems based on risk assessment principles. There is also a need for the harmonization of guidelines for inspection and certification procedures in international trade. The Codex "Principles for Food Import and Export Inspection and Certification" recommends government to government assurance that basic quality standards, including those for food safety, are met. The Codex Committee on Food Import and Export Inspection and Certification Systems has developed "Guidelines for the Design, Operation and Assessment and Accreditation of Food Import and Export Inspection and Certification Systems" which were adopted by the twenty-second Session of the Codex Alimentarius Commission in 1997. "Draft Guidelines for the Development of Equivalence Agreements regarding Food Import and Export Inspection and Certification Systems" have been advanced to Step 8 of the Codex elaboration procedure.

5.2 Impact of L. monocytogenes on trade

A comprehensive assessment of the impact of different standards for L. monocytogenes on trade of fish and fishery products is not available. However, preliminary studies provide some evidence of trade impact because of rejections or detentions of imported products. Published data suggest that some of these cases would not have occurred if standards were harmonized. Further analysis is needed before the impact of this pathogen on trade of fish and fishery products can be quantified.

Table 4 presents data on fishery products recalled from the market by some European Union countries because of contamination by L. monocytogenes between January 1998 and March 1999.

Table 4: Fish products removed from the EU market between January 1998 and March 1999 because of contamination by L. monocytogenes

* The Austrian authorities seized the distributed product. The press was informed. Listeria present in 25g

Source: Food Alerts in the EU January 1998-March 1999

The USFDA has taken strong action against many processors due to the presence of L. monocytogenes. Since 1985, Class I recalls have been imposed on ready-to-eat foods contaminated with L. monocytogenes, including cheeses, ice-cream, milk, fish, prepared salads, sandwiches, crab meat, smoked fish, and bakery products. From 1987 to 1992, there were recalls on 970 ready-to-eat products from 109 firms because of contamination with this organism. Between 1987 and August 1998 there were 112 Class I recalls for domestic or imported ready-to-eat seafood products (Table 5).

Table 5: US Class I recalls issued in the United States for domestic and domestic/imported ready-to-eat seafood products contaminated with L. monocytogenes since 1987

* Hot or cold smoking process not identified.

Data compiled from FDA Enforcement Reports

Source: Adapted from Jinneman, K.C., Wekell, W.W. and Eklund, M.W. 1999. Incidence and behaviour of Listeria monocytogenes in Fish and Seafood, p 601-630. In Ryser, E.T. and Marth, E.H., eds., Listeria, Listeriosis and Food Safety, 2^nd edition, Marcel Dekker, Inc. New York.

Out of 323 samples of imported products analyzed by the Canadian Food Inspection Agency in 1997 and 1998, one sample of cooked shrimp was rejected due to the presence of Listeria (Table 6).

In addition to the direct costs of rejections and detentions, there are additional economic costs that result from inspection/re-inspection at port-of-entry, delays in distribution, transportation, expiry of shelf-life, and the opportunity cost of holding products.

Table 6: Imported fishery products inspected in Canada for the presence of L. monocytogenes in 1997-98

^a One of these samples contained L. monocytogenes.

^b The incidence of L. monocytogenes contamination in imported fishery products was 0.3% (1 positive out of 323 products tested).

Source: Data supplied by the Canadian Food Inspection Agency (CFIA) in Ottawa

5.3 Microbiological criteria

Currently there is no international agreement on ‘acceptable levels’ of L. monocytogenes in foods, including fishery products. In several countries, criteria or recommendations for tolerable levels of L. monocytogenes in ready-to-eat foods, have been established. Some countries like USA, Austria, Australia, New Zealand and Italy require absence of L. monocytogenes in 25 g of foods (referred to as zero-tolerance). Other European countries (e.g. Germany, Netherlands and France) have a tolerance of less than 100 cfu g^-1 at the point of consumption. Others (e.g. Canada and Denmark) have a tolerance of less than 100 cfu g^-1 for some foods and a zero-tolerance for other foods, especially those with extended shelf-lives that can support the growth of L. monocytogenes. In addition to differences in criteria for L. monocytogenes, several countries use different sampling plans and methodologies, which make matters more complex. Therefore, there is a need to harmonize microbiological criteria for L. monocytogenes in foods at international level, based on the principles of risk assessment.

While details on the policy on L. monocytogenes in all countries is not available, examples from some countries are discussed here.

The detectable presence of L. monocytogenes in ready-to-eat food is considered to be a hazard to health under current US FDA policy. The limit of sensitivity of the analytical method is actually 1 cfu per 25 g (0.04 cfu g^-1).

In Canada, foods have been placed into 3 categories, based upon health risk. Products in Category 1 have been causally linked to outbreaks of listeriosis and receive the highest priority in inspection and compliance activities. Currently, there are no fishery products included in this category. Category 2 contains all other ready-to-eat foods which are capable of supporting growth of L. monocytogenes and have a shelf-life exceeding 10 days (in this category the action level is absence in 25 g). Category 3 contains two types of ready-to-eat food products; those supporting growth with a < 10 day shelf-life and those not supporting growth. These products receive the lowest priority in terms of inspection and compliance action. For Category 3 ready-to-eat foods, factors such as the presence or absence of Good Manufacturing Practice (GMP), levels of L. monocytogenes in the food (action level of 100 cfu g^-1) and/or a health hazard evaluation are all considered in the compliance action taken.

In Denmark, ready-to-eat foods have been placed into six categories where absence of L. monocytogenes in 25 g is required in heat treated foods and in otherwise preserved, not heat treated foods that are capable of supporting growth within the shelf-life. This level is necessary in foods capable of supporting growth, in order not to exceed 100 L. monocytogenes per gram at the point of consumption. In heat treated and preserved foods that do not support growth within the shelf-life and for raw, ready-to-eat foods, a level below 10 L. monocytogenes g^-1 is regarded as acceptable, a level between 10 and 100 g^-1 is not satisfactory and a level above 100 g^-1 is not acceptable.

The International Commission for Microbiological Specifications for Foods (ICMSF) states that sampling of food for microbiological testing and the use of criteria are insufficient to ensure food safety. However, these tools are useful as part of the verification programme to ensure that the HACCP-plan is working. Thus, according to ICMSF, for:

• in-pack, heat-treated products – no testing is necessary (documentation for the heat-treatment process);
• raw products and/or products which are to be heat-treated before consumption – no testing is necessary;
• ready-to-eat products, unable to support growth of L. monocytogenes – 10 samples should be taken and the lot should be rejected if any sample contain > 100 L. monocytogenes g^-1;
• ready-to-eat products, able to support growth of L. monocytogenes – 20 samples should be taken and the lot rejected if any sample contains > 100 L. monocytogenes g^-1.

More recently, international criteria for L. monocytogenes have been discussed by a Working Group of the Codex Committee for Food Hygiene. This Working Group agreed to propose to the Codex Committee on Food Hygiene to recognize that numbers of L. monocytogenes not exceeding 100 g^-1 in food at the time of consumption is of low risk to the consumer. Furthermore, with respect to imported foods, it agreed to recommend that lower levels may need to be applied at the port-of-entry for foods that support the growth of L. monocytogenes, in order not to exceed 100 cfu g^-1 at the point of consumption.

5.4 Recommendations for establishing criteria

Microbiological testing of products does not ensure food safety. Food safety is only improved through efficient implementation of GMP and HACCP systems, including prerequisite programmes. Microbiological criteria may be used to help producers in applying HACCP. Microbiological criteria may also be applied when the history of a food product is unknown or when documentation for efficient and adequate application of HACCP is not available. Sampling plans should be developed taking into account the risk level of each product.

The regulatory policy for L. monocytogenes in foods should be based on principles of HACCP and those measures necessary to achieve an appropriate level of public health protection as determined by risk assessment approaches. The criteria for L. monocytogenes in foods should be applicable to ready-to-eat foods at all points during the product shelf-life. A risk assessment approach using current scientific knowledge was used to develop a proposal for a decision tree to assist the establishment of criteria for L. monocytogenes to be used in international trade (Figure 1).

Factors including freezing, pH, water activity, lactate and organic acids may be used to reduce the growth of L. monocytogenes, but in some cases it will be difficult to assess whether a food can support the growth of this bacterium within the stated shelf-life. In such cases, a conservative approach may be taken and growth regarded as possible, unless it can be documented that the product does not support growth. It is a responsibility of the manufacturer to provide the necessary documentation to show that the product can not support the growth of the organism. Such documentation might include challenge tests and/or shelf-life studies.

In order to be able to assess whether a product can support growth of L. monocytogenes within the stated shelf-life information about the actual length of shelf-life must be given by the manufacturer. Therefore, it is strongly recommended that the length of the shelf-life together with either the production date or the "use-by-date", as well as recommended conditions for storage be stated on the package.

With the current technology used in the food industry it is possible that low numbers of L. monocytogenes can occur sporadically in a number of different fishery products, including cold smoked salmon. Therefore, it is recommended that these products should have a "use-by-date" such that at the end of product shelf-life L. monocytogenes numbers will be less then 100 cfu g^-1. Furthermore, health authorities should ensure that the stated shelf-life for ready-to-eat products that support the growth of L. monocytogenes are within safe limits and that highly susceptible individuals are informed and provided with guidelines about safe handling of food.