Purpose of the assessment

The purpose of the assessment is to estimate the risk of Histamine Fish Poisoning (HFP) from tuna fish that caught and processed in Iran.


For forming this semi- quantitative risk assessment ,we used from Risk Ranking Program.  Risk Ranger is a simple and accessible food safety risk calculation tool intended to help determine relative risks from various product/pathogen/processing combinations and is presented in Microsoft® Excel spreadsheet software. In particular, it is intended to make the techniques of food safety risk assessment more accessible to non-expert users, and to users with limited resources, both as a decision-aid and an educational tool.

Risk Ranger incorporates all factors that affect the risk from a hazard in a particular commodity including:

• severity of the hazard and susceptibility of the population of interest;

• likelihood of a disease-causing dose of the hazard being present in a meal;

• number of meals consumed by a population of interest in a given period of time.

Risk Ranger combines the factors in Questions 1–11, including some logical tests to generate three estimates of risk:

• risk ranking – a score between 0–100;

• predicted annual illnesses in the population you selected;

• probability of illness per day in target population;


Hazard identification

Traditionally, HFP has been associated with consumption of scombroid fish from the families Scombridae and Scomberosocidae (mackerels, tunas and kingfish). More recently, non-scombroid fish have also caused identical symptoms and so “Scombroid poisoning” may not be the best description – hence the use of HFP to describe the symptoms.

The illness

The illness has a range of symptoms .


Flushing, urticaria (nettle-rash),   hypotension (low blood pressure) and headache


Abdominal cramps, diarrhoea, vomiting


Pain and itching associated with the rash

Outbreaks of HFP

Histamine poisoning occurs throughout the world and is perhaps the most common form of toxicity caused by the ingestion of fish. However, reliable statistics about its incidence do not exist because the poisoning incidents are often unreported because of the mild nature of the illness, lack of adequate systems for reporting food-borne diseases or ignorance by medical personnel who misdiagnose histamine poisoning as a food allergy (Taylor, 1986; Lehane and Olley, 2000). Japan, the United States and the United Kingdom are the countries with the highest number of reported incidents, although this possibly reflects better reporting systems. Frequent incidents have been reported elsewhere in Europe, Asia, Africa, Canada, New Zealand and Australia (Ababouch et al., 1991; Lehane and Olley, 2000).

Fish species most commonly implicated

Species in the families Scombridae and Scomberosocidae that have been implicated in outbreaks of HFP include: mackerel (Scomber spp.), tuna (Thunnus spp.), saury (Cololabis saira) and bonito (Sarda spp.). Non-scombroid fish include: mahi-mahi (Coryphaena spp), sardines (Sardinella spp.), pilchards (Sardina pilchardus), marlin (Makaira spp.), bluefish (Pomatomus spp.), sockeye salmon (Oncorhynchus nerka), yellowtail (Seriola lalandii) and Australian salmon (Arripis trutta).

Formation of biogenic amines

The biogenic amines are produced in fish tissues by bacteria in the family Enterobacteriaceae, e.g. Morganella, Klebsiella and Hafnia. The bacteria produce decarboxylases that convert amino acids in the fish to biogenic amines:

Histidine → Histamine

Ornithine → Putrescine

Lysine → Cadaverine

The bacteria are naturally occurring in the gills and intestines of the fish and may be spread to other sites in the fish during handling. Once histidine decarboxylase has been produced, it may continue to produce histamine, even though bacterial growth has been prevented by chilling to 4 °C. Ababouch et al. (1991) showed that histamine production can increase even in ice storage.

Hazard characterization

HFP is caused by the ingestion of foods that contain high levels of histamine and possibly other amines and compounds. Neither cooking, canning, nor freezing reduces the toxic effect (Shalaby, 1996; FDA, 1999).

Infectious dose/dose response

The threshold toxic dose for histamine is not precisely known and scombroid poisoning has occurred at histamine levels as low as 50 mg/kg. However, most incidents involve fish with histamine levels of 200 mg/kg and over (Fletcher, Summers and van Veghel, 1998). The variation may reflect the role that biogenic amines other than histamine play in scombroid poisoning.

Simidu and Hibiki (1955) estimated the threshold toxic dose for histamine in fish at approximately 60 mg. Shalaby (1996) reviewed the oral toxicity to humans of histamine and other biogenic amines in foods. He considered that histamine-induced poisoning is, in general, slight at <40 mg, moderate at >40 mg and severe at >100 mg. Based on an analysis of recent poisoning episodes, Shalaby (1996) suggested the following guideline levels for histamine content of fish:

• <5 mg/100 g (safe for consumption)

• 5–20 mg/100 g (possibly toxic)

• 20–100 mg/100 g (probably toxic)

• >100 mg/100 g (toxic and unsafe for human consumption)

In the United Kingdom, guidelines for histamine levels in fish (Scoging, 1998) are:

• Safe <10 mg/100 g

• Potentially toxic 10–50 mg/100 g

• Probably toxic 50–100 mg/100 g

• Toxic >100 mg/100 g

The United States FDA guidelines, established for tuna, mahi-mahi and related fish, specify 50 mg/100 g as the toxicity level, and 5mg/100 g as the defect action level because histamine is not uniformly distributed in fish that has undergone temperature abuse. Therefore, if 5 mg/100 g is found in one section, there is a possibility that other units may exceed 50 mg/100 g (FDA, 2001a). The European Union (EU, 1991, 1995) requires that nine samples be taken from each batch of fish species of the following families: Scombridae, Clupeidae, Engraulidae and Coryphaenidae. These samples must fulfil the following requirements:

• Mean value of all samples must not exceed 10 mg/100 g

• Two samples may be >10 mg/100 but <20 mg/100

• No sample may exceed 20 mg/100

In Australia and New Zealand, the level of histamine in a composite sample of fish or fish products, other than crustaceans and molluscs, must not exceed 20 mg/10 g. A composite sample is a “sample taken from each lot, comprising five portions of equal mass from five representative samples”.

Susceptible populations

It is widely believed that all humans are susceptible to scombroid poisoning (FDA, 1999) though symptoms can be severe for the elderly (FDA, 1999) and for those taking medications such as isoniazid, a potent histaminase inhibitor (Morinaga et al., 1997).

Inputs for Risk Ranger

Question 1: Disease is mild, requiring medical attention only rarely

Question 2: General population is at risk with no susceptible population categories

Exposure assessment

Volumes of  tuna fishes that catch in Iran are about 190000mt .

Edible weight and number of servings

After processing and canning , the actual weight is about 80000 tonnes and, assuming that 100 g is a typical serve, there are 800 million annual servings that consumed .

Consumption patterns in consumer country

Market data tells us that a few (10 percent) people in the our country ever eat canned tuna. The population of  Iran is 70 million, which means that 800 million servings of tuna are eaten by 7 million consumers. This means that each consumer has an average of 11 servings each year.

Inputs to Risk Ranger for probability of consuming fish that may have histamine

Question 3: Frequency of consumption                           Few times a year

Question 4: Proportion consuming                                  Very few (5 percent)

Question 5: Population                                                      70 000 000

Contamination of fish on the boats

Histamine-producing bacteria such as Morganella, Klebsiella and Hafnia convert amino acids in the fish to biogenic amines like histamine. These bacteria occur naturally in the gills and intestines of the fish and are spread to other sites in the fish during catching and handling.

Factors which affect build up of histamine and other biogenic amines in seafoods include:

• Free histidine levels in fish muscle.

• Location of histamine-producing bacteria: The gills, intestine and skin of fish are contaminated with these bacteria and after death of fish, meat near these site are more susceptible to contaminated . These are termed “sites of microbiological concern” because it is here that histamine is produced.

• Temperature at which product is stored: If temperature at the sites of microbiological concern is controlled, histamine production is controlled.

It is important to know the levels of histamine-producing bacteria on tuna after on-board handling. In a study on Pacific mackerel (Scomber japonicus), Kim et al. (2001) found very low levels of histamine-producers (<10 cm2 on the gills and <10 g in the gut), and these organisms produced histamine only slowly at 4 °C and not at all at 0°C. This finding is typical of many others, which indicate that histamine formation is controlled by temperatures at 4 °C or below.

At abusive temperatures (20–30 °C), however, histamine is formed quickly and, importantly, the enzyme histidine decarboxylase is produced and excreted from the bacterial cells onto the fish muscle. The enzyme is active at 0°C as indicated by Ababouch et al. (1991) who showed that on sardine held at ambient temperature (approx 25 °C) for 24 hours, histamine continued to be produced even after the fish had been placed in ice storage for a week. Klausen and Huss (1987) similarly showed that after mackerel had been held at 10 °C for two days, histamine continued to increase even when the fish were stored in ice.

So it is vital to quickly cool the sites of microbiological concern on fish to prevent formation of histidine decarboxylase. On ungutted fish these are the skin, gills and gut contents. However, in the system under review, there is no cooling for up to 10 or more hours.

Temperature: time parameters for fish on boats

Typically, traditional fishing vessels go in a trip of up to 28 days. Travel to the fishing grounds takes about one week, gill nets are set and the first fish are caught  about 24 hours into the trip. Storage is at partial ice until unloaded at the processing plant – the first-caught fish have been already stored for up to 20 days. As fish are caught throughout the trip they are added to the catch in the bottom of the boat and kept cool with ice. Fish from the last set are landed about one week before the vessel arrives home.

For inputs to Risk Ranger, only assumptions can be made on the rate at which servings are contaminated.

Assumption 1: That all (100 percent) tuna landed contain histamine-producing bacte­ria in the gills and gut, and on the skin (see Kim et al., 2001).

Assumption 2: That these bacteria are present at 10/cm2 of gill surface or 10/g of gut contents (see Kim et al., 2001).

Assumption 3: That the contamination is confined to fish surfaces, and the deep muscle tissues remain sterile.

Assumption 4: That a 5 kg tuna will give around 20 servings of 100 g of which 1 percent (servings with external tissues on which histamine has been produced) will be contaminated with sufficient histamine to cause illness.

Assumption 4: That during processing, there is a recontamination rate because the numbers of histamine-producers will have multiplied.

Assumption 5: That in fish held at 25–28 °C, histamine-producers have a doubling time of 60 minutes without any delay due to lag phase (typical doubling time for mesophilic Enterobacteriaceae).

Inputs to Risk Ranger for contamination with histamine-producing bacteria on fish at time of landing aboard the vessel

   Question 6: Frequency of contamination                           10 percent

   Question 7: Effect of process                                              No effect

Question 8: Potential for recontamination                         1 percent

Question 9: Effectiveness of post-processing                   No effect in hazard


Assess potential for product to reach toxic level

At this stage you must decide how much the growth of histamine-producers will cause fish to become toxic to consumers.

In the United Kingdom, levels of histamine >10 mg/100g fish are considered to be potentially toxic (Scoging, 1998) while in Australia the Food Standards Code has set 20 mg/100 g as the upper limit in any sample. The United States FDA set a level of concern at 10 mg/100 g.

Fletcher et al. (1998) showed that histamine-producers generally must reach a level >107/cm2 to cause levels of histamine >5 mg/100 g so, for the present assessment, an assumption was made that a level of 108/cm2 was needed for fish to be toxic.

Question 10: Increase to intoxication                        10 fold increase in histamine producers

Determine effect of meal preparation on toxin levels

Histamine is heat-stable and so the method of preparation in the home or restaurant has no effect on the level of toxicity in the fish.

Inputs to Risk Ranger for effect of meal preparation

Question 11: Effect of meal preparation:              Preparation has no effect on       the hazard

Risk estimate

The risk ranking is 56 with estimated annual illness of 11000 from total servings numbering around 800 million.


Ababouch, L., Afilal, M.E., Benabdeljelil, H. & Busta, F.F. 1991. Quantitative changes in bacteria, amino acids and biogenic amines in sardine (Sardina pilchardus) stored at ambient temperature (25–28 °C) and in ice. International Journal of Food Science and Technology, 26: 297–306.

European Union (1991 and 1995). Council Directive 91/493/EEC and 1995 amendment laying down health conditions for the production and placing on the market of fishery products. Official Journal of the European Commission, L268: 15–32.

FAO. 2004. Application of risk assessment in the fish industry, by J.Summer, T.Ross and  L. Ababouch . FAO Fisheries Technical Paper 442. Rome.

     FDA. 1999. Bad bug book (foodborne pathogenic microorganisms and natural toxins). Washington, DC.

FDA. 2001a. Fish and fishery products hazards and controls guide. 3rd edition. Washington, DC, Office of Seafood. 326 pp.

Fletcher, G.C., Summers, G. & van Veghel, P.W.C. 1998. Levels of histamine and histamine-producing bacteria in smoked fish from New Zealand markets. Journal of Food Protection, 61(8): 1064–1070.

Kim, S-H., Field, K.G., Chang, D-S., Wei, C-I. & An, H. 2001. Identification of bacteria crucial to histamine accumulation in Pacific mackerel during storage. Journal of Food Protection, 64(10): 1556–1564.

Klausen, N.K. & Huss, H.H. 1987. Growth and histamine production by Morganella morganii under various temperature conditions. International Journal of Food Microbiology, 5: 147–156.

Lehane, L. & Olley, J. 2000. Histamine fish poisoning revisited. International Journal of Systematic Microbiology, 58: 1–37.

Morinaga, S., Kawasaki, A. Hirata, A.H. Suzuki, S. & Mizushima, Y. 1997. Histamine poisoning after ingestion of spoiled raw tuna in a patient taking isoniazid. Internal Medicine, 36(3): 198–200.

Scoging, A. 1998. Scombrotoxic (histamine) fish poisoning in the United Kingdom: 1987 to 1996. Communicable Disease and Public Health, 1: 204–205.

Shalaby, A.R. 1996. Significance of biogenic amines to food safety and human health. Food Research International, 29(7): 675–690.

Simidu, W. & Hibiki, S. 1955. Studies on putrefaction of aquatic products. 23. On the critical concentration of poisoning for histamine. Bulletin of the Japanese Society of Scientific Fisheries, 21:365 (cited by Taylor, 1986).

Taylor, S.L. 1986. Histamine food poisoning: Toxicology and clinical aspects. Critical Reviews in Toxicology, 17(2): 91–128.


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