Scombrotoxin fish poisoning (SFP), often called “histamine poisoning”, is caused by ingestion of certain species of marine fish that contain high levels of histamine and possibly other biogenic amines. The fish species involved contain high levels of free histidine in their tissue and include tuna (which accounts for 8% of globally traded fish) and other pelagic species like mackerel, sardines, and anchovy, which account for significant global fish production. When these fish are subjected to temperature abuse during and/or after harvest, bacterial decarboxylation of histidine leads to histamine formation. Other biogenic amines produced during bacterial growth in fish may potentiate histamine’s effect. Severity of the symptoms can vary depending on the amount of histamine and other biogenic amines ingested and the individual’s sensitivity to specific biogenic amines. In some parts of the world, SFP accounts for the largest proportion of cases of fish-borne illness.
For the purposes of consumer protection, fish importing countries have regulations and varying limits for histamine in fish and fishery products. Codex Alimentarius through its standards and guidelines aims to provide countries with the basis for which to manage issues such as histamine formation. For example, the Codex Code of Practice for Fish and Fishery Products provides guidance on fish handling practices that need to be implemented to minimize food safety problems including SFP. In addition, the Codex Alimentarius has established several standards which include maximum levels for histamine in different fish and fishery products. Different limits have been established as indicators of decomposition and as indicators of hygiene and handling. However, the associated guidance on the relevant sampling plans and other aspects of sampling have been limited or even non-existent. Furthermore, many of these limits were established in a pre-risk assessment era and the scientific basis for the limits is unclear. As food safety management moves towards more risk and evidence based approaches, there is a need to review existing limits in light of the most up to date scientific information and ensure there is a robust scientific basis for any limits recommended by Codex.
FAO and WHO have developed a tool to support decision-making related to the establishment and/or use of sampling plans for detection of histamine. The tool provides support in two main areas related to sampling for histamine:
Designing a Sampling Plan This tool function attempts to find sampling plans which meet user-defined objectives, by searching for combinations of the number of samples (n) and a concentration threshold (m).
Analyzing the performance of a Sampling Plan This tool function estimates the probability of accepting lots of product tested according to a user-defined sampling plan.
The FAO/WHO histamine sampling plan tool is a free resource tool and is available at www.fstools.org