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Marine Biotoxin Monitoring and Response Manual for Non-Commercial Shellfish

4 INTRODUCTION

4.1 Background

New Zealand shellfish have been monitored for the presence of marine biotoxins since January 1993 when shellfish toxicity was first detected in New Zealand.

Since 2002, NZFSA has been responsible for monitoring the safety of non-commercially harvested shellfish from harmful marine biotoxins through contracts with DHBs and other agencies for sampling and management services, and through contracts with science providers for analytical and advice services.

DHBs issue warnings to the public about the risks of consuming non-commercial shellfish when toxicity in shellfish exceeds pre-determined limits. DHBs are contracted by the Ministry of Health to issue these warnings. NZFSA also maintains a web site advising the public about areas subject to warnings.

DHBs also manage marine biotoxin monitoring programmes in commercial shellfish harvesting areas under contract to the shellfish industry via local marine biotoxin management plans. These local plans are required by the Animal Products Regulated Control Scheme for Bivalve Molluscan Shellfish.

Data from both programmes are shared in the FoodNet database administered by the NZFSA.

4.2 Marine Biotoxins of Public Health Concern

Table 1: Marine Biotoxins of Public Health Concern Routinely Found in New Zealand

Toxins	Poisoning Syndrome	Symptoms	Warning Level	Analytical Test Method
Saxitoxins	Paralytic Shellfish Poisoning (PSP)	Numbness and tingling around the mouth, face or extremities; difficulty in swallowing or breathing; dizziness; double vision. In severe cases, paralysis and respiratory failure within 12 hours of consuming shellfish	0.8mg/kg	Mouse bioassay
Domoic Acid	Amnesic Shellfish Poisoning (ASP)	Diarrhoea and vomiting, within 24 hours of consuming shellfish (mild cases), and/or confusion, memory loss and disorientation within 48 hours of consuming shellfish (Severe cases)	20mg/kg	HPLC
Okadaic Acid and its esters (DTX1, DTX2, DTX3)	Diarrhetic Shellfish Poisoning (DSP)	Diarrhoea, nausea, vomiting and abdominal pain, within 12 to 24 hours of consuming shellfish	0.16mg/kg	ELISA

Neurotoxic Shellfish Poisoning (NSP) cases may have occurred in 1993 from an unidentified algal source (believed to be a Karenia species) and brevetoxins were found in some shellfish harvested at that time, however no significant NSP toxicity has been detected since. Some Karenia species may also cause respiratory irritation syndrome. In the event of significant blooms of likely causative species (refer Appendix 1) shellfish should be tested for the presence of NSP.

Other substances such as Yessotoxin, Pectenotoxin and Gymnodimine have been monitored for historically because they failed mouse bioassay tests which were used to test for DSP. However more toxicological work has been done over time and these are not known to be of any human health significance and are no longer monitored for in the public health monitoring programme. (Some continue to be monitored for in the commercial monitoring programme to meet market access requirements.)

4.3 DHB Responsibilities

Health Protection staff in DHBs are responsible for the public health management of marine biotoxins in commercial and non-commercial areas. This includes: opening and closing commercial growing areas, domestic market product recall pursuant to the Food Act 1981, and warning the public when non-commercial harvesting areas exceed public health warning limits for the collection and eating of shellfish and when there is a risk of Respiratory Irritation Syndrome (RIS). (RIS is a condition caused by inhalation of fractured toxic algal cells in sea spray. This is known to be associated with some Karenia species and may occur when a bloom coincides with onshore winds and a surf beach for example.) Most DHBs also have responsibility for and are contracted to undertake sample collection in their areas.

DHBs that are also Sampling Providers are responsible for maintaining a local marine biotoxin management plan that contains:

• agency and personnel contact details at local and national levels

• a list of commercial and/or non-commercial shellfish gathering areas and their locations

• a map showing the marine biotoxin sampling sites (both phytoplankton and shellfish collection sites) for each commercial and/or non-commercial gathering area

• procedures, including safety precautions, for sampling each site

• the frequency of shellfish and phytoplankton monitoring for each commercial and/or non-commercial gathering area

• procedures for phytoplankton and shellfish sample collection and dispatch (this should include what environmental data is to be collected at each site e.g. temperature, salinity etc)

• contingency plans for e.g. bad weather, unavailability of regular staff

• procedures for notifying results to industry

• procedures for issue of TSP and RIS public health warnings

• locations for signage to be erected

• draft media statements and wording for signage

• procedures for detention and recall of harvested product in accordance with IAIS and NZFSA recall protocols for domestic market product

• surveillance procedures for closed commercial and/or non-commercial areas

• procedures for providing TSP information to Medical Practitioners.

Where both commercial and non-commercial areas are under the jurisdiction of a single DHB, a single, integrated plan may cover both types of harvesting areas.

4.4 Responsibilities of Non-DHB Sampling Providers

Each Sampling Provider (this section applies to non-DHB Sampling Providers) must document and maintain a local marine biotoxin sampling plan that contains:

• agency and personnel contact details at local and national levels

• a list of non-commercial shellfish gathering areas and their locations

• a map showing the marine biotoxin sampling sites (both phytoplankton and shellfish collections sites) for each non-commercial gathering area;

• procedures, including safety precautions, for sampling each site

• the frequency of shellfish and phytoplankton monitoring for each non-commercial gathering area

• procedures for phytoplankton and shellfish sample collection and dispatch (this should include what environmental data is collected at each site e.g. temperature, salinity etc)

• contingency plans for e.g. bad weather, unavailability of regular staff

• procedures for notifying results to industry

• protocol for communication with local and neighbouring DHBs

4.5 Funding

The NZFSA, through specific marine biotoxin contracts with DHBs and Sampling Providers, funds both routine and Event-related non-commercial marine biotoxin monitoring activities.

Regulatory activities such as actioning food recalls as a result of marine biotoxin closures of commercial growing areas are funded separately by NZFSA.

The MoH funds the public health activities listed below. However funding for these activities is via the general contracts between the MoH and each DHB, for the provision of public health services as specified in the Public Health Services Handbook.

The MoH funded public health activities can be summarised as follows:

• Issue of public warning, posting of signage and associated media response during marine biotoxin Events

• Investigation of suspected toxic shellfish poisoning cases and sampling and analysis associated with such investigations

• Data entry of all case investigation details.

4.6 Marine Biotoxin Technical Committee

NZFSA and the New Zealand Seafood Industry Council (SeaFIC) have a standing technical committee. Although the MBTC’s primary focus is on commercial shellfish, it also considers those elements of the non-commercial and commercial programmes that are interlinked. The MBTC deals with the following matters:

• Amendments to the National Marine Biotoxin Management Plan

• Approval of changes to local marine biotoxin management plans for commercially harvested shellfish, such as sample site location, sample species and sampling frequency

• Review of opening and closure criteria

• Laboratory specifications and approval of analytical methodology.

The MBTC also runs annual marine biotoxin science workshops and acts as a focal point for research information exchange both in New Zealand and overseas.

The Technical Committee can be contacted through:

The Senior Programme Manager (Seafood)

New Zealand Food Safety Authority

P.O. Box 2835

Wellington