Fish, crustaceans and molluscs: Hazard overview

Legislation: Fish, crustaceans and molluscs

Table 1 Regulations in fish, crustaceans and shellfish derived from the Status of food-safety (Dutch Food Safety Authority)

Regulation	Description
(EC) No 178/2002	General principles and requirements of food law establishing the European Food Safety Authority and laying down procedures in matters of food safety
(EC) No 853/2004	Hygiene in the production of products of animal origin
(EC) No 2073/2005	Microbiological criteria for food
(EC) No 854/2004	Official controls on food from animal products
(EC) No 1881/2006	Determining maximum levels of certain pollutants

Microbiology of fish, crustaceans and molluscs

Table 2 Common microbiological hazards (The full table, with extensive information on the hazards, can be found at the link.)

Genus	Pathogenic species	GR	Form, mobility	O₂	T (C.)	T1 (C.)	pH-O	pH-R	aW	Illness
Aeromonas	hydrophilic, sobria, caviae	–	Rod, mobile	Fa	20-35	4,0-42,0		4,0-10,0	>0.97	Infection: diarrhoea, stomachache and vomiting.
Bacillus	cereus	+	Rod (3-5 um length 1 um wide) spore forming, mobile	Aerobe (sometimes Fa)	28,35	10,0-48,0	6-7,5	4,9-9,3	>0.91	Poisoning (Tox. 1) and infection (Tox. 2)
Campylobacter	jenuni, coli	–	Spiral formed rod, mobile.	Min. 3 % Max. 15 % opt. 5 % oxygen	42-45	30-47	6,5 – 7,5	4,9 – 9,5	> 0.98	Infection: Stomachache, diarrhoea, fever, sometimes meningitis.
Listeria	monocytogenes (11 species; 3 cause 90% of the infections)	+	Rod (0,5-2,0um long, 0,5um wide), mobile at 20-25°C.	Fa	3,0-37,0	0-45	7	5-9 (at 4gr. C) 4,4-9,0 (at 30grC)	> 0.92	Infections of healthy individuals lead to flu symptoms. Infants, the Elderly, the ill and pregnant women might get severe symptoms when infected by Listera. (Meningitis, blood poisoning and abortion). In these risk groups is the mortality 30-50%.
Plesiomonas	shigalloides	–	Rod	Fa	37-38	8,0-44,0		5-7,7		Infection: stomach and intestine complaints (diarrhoea, stomachache, vomiting) could cause meningitis in sensitive individuals (very young children, elderly and immunodeficiency
Salmonella	Two thousand three hundred species that might cause enteritis (stomach inflammation).	–	Rod, sometimes mobile	Fa	35-37	5,0-45,0	7	4,0-9,0	>0.93	Infection: intestinal inflammation. For the elderly, small children and sick, illness can be fatal.
Salmonella	typhus; paratyphus	–	Rod	Fa	37	5,0-45,0			>0.93	Typhus, paratyphus are the most severe illnesses caused by Salmonella.
Yersinia	entero-colitica (some species are pathogenic)	–	Rod, sometimes round, sometimes mobile	Fa	32-34	0-44	7,0-8,0	4.6-9.0 at 25° C	>0.96	Infection: diarrhoea, a disease similar to appendicitis and is rarely fatal.
Vibrio	cholera	–	Vibrio formed, mobile.	Fa	30-37	15-42		6,0-10,0	>0.94	Cholera

 Table 3 Viruses, rickettsia in fish, crustaceans and shellfish products, derived from Hazard table Viruses, rickettsia, prions

Virus, ricket, prion	Origin	Food product	MID	Disease	Preventive Measurements	Comments
Hepatitis-a	Human	All food products are contaminated by humans or food that is contaminated by faecal polluted water →, especially shellfish.	A few virus particles	Infectious jaundice. Incubation period: 2 to 6 weeks.	Personal hygiene. Contaminated staff should not process raw materials. Heat several minutes at 85-90 ° C. Sensitive target groups should prevent shellfish consumption.	Chlorination resistant. Because of the long incubation time, is it difficult to trace the origin.
Viral-gastro-enteritis (stomach flu with diarrhoea, stomach ache and vomiting) viruses (adenovirus, astrovirus, calicivirus, coronavirus, Norwalk virus, rotavirus)	Human	All food products direct or through aerosols or vomiting by Human contaminated or faecal polluted water → especially shellfish.	A few virus particles	Gastroenteritis. Incubation time is 12-50 hours; infants and small children are extra sensitive to viruses.	Personal hygiene. Contaminated persons should prevent the handling of raw materials. Heating: several minutes at 85-90 ° C. Sensitive target groups should prevent shellfish consumption.	Norwalk virus is the most common among older children and adults. However, rotavirus could be fatal for infants and young children. In addition, 30% of gastroenteritis is caused by viruses (not necessarily through food!).
Norwalk-like (Norovirus) viruses (part of the Calici-virus family.		Before consumption, shellfish and washed fruits and vegetables are food products without heat treatment.	10-100 (very low)	Infection caused explosive diarrhoea, nausea, vomiting and fever. Children mainly vomit. Incubation period: 24-48 hours. The duration disease is two days. o Medication is not available and necessary. All consumers are prone to infections. Groups with decreased immunity (YOPIs) have an increased risk. Infected people stay three days after being symptom-free contagious. Infected people stay three days after being symptom-free contagious.	Do not use water that faeces might contaminate from producing fresh food products. O, Heat one and a half minutes at 90 °C to inactivate viruses. Improve hygiene of the whole food chain. Staff employees who are probably contaminated should conduct different work, even after the disappearance of the symptoms. Inhibit virus outbreaks in places where contaminated shellfish are being cultivated. Development of microbiological quality criteria for viruses.	NLV viruses are very contagious. Toxins are not being formed. This type of virus could cause outbreaks in places where humans live in close communities. Days can survive when a product is heated insufficiently. There is no legislation for the inhibition of viral food infections. The virus needs bacteria to reproduce.

Chemistry: Fish, crustaceans and molluscs

Table 4 possible chemical hazards

Chemical component	Food product	Legislation	Comments
Dioxins: Polychlorinated dibenzodioxins (PCDD’s), Polychlorinated dibenzofurans PCDF and 2,3,7,8-Tetrachlorodibenzodioxin (TCDD).	Herbs (through Feed) and poultry, fish (especially fatty fish such as herring and salmon) and Vegetables, Oils/fats, dairy and eggs	Maximum levels according to Regulation (EC) No 1881/2006	Formed from chlorinated linkages during heating with low oxygen levels. Carcinogenic for humans and animals above a threshold level.
Polychlorinated biphenyls (PCBs) and dioxin-like PCBs (dl-PCBs)	Herbs (through Feed), poultry, fish (especially fatty fish such as herring and salmon), Vegetables, Oils/fats, dairy and eggs	Maximum levels according to Regulation (EC) No 1881/2006	Carcinogenic for animals and humans. Moreover, it might induce skin disorders, reproductive toxicity and liver diseases. PCBs burn above 1200 °C, are insoluble and are applied as plasticizers, paint, ink, lacquer, glue and insecticides.
Polybrominated diphenyl ethers	through water in fish.

Biotoxins: Fish, crustaceans and molluscs

Table 5 possible biotoxins in fish, shellfish and crustaceans.

Name Biotoxin	Origin	Food product	The lethal dose (µg)	Illness	Preventive measurements	Comments
Ciguatera fish poisoning (CFP)	Single cell-based dinoflagellate: Gaberdiscus toxicus, living in tropical reefs	Fish that directly consumed plants or indirect through other fish.		Neurotoxin: paralysis could result in death, however, the mortality is low (2-7%); illness could last long and the incubation time is around 30 hours.	Control of tropic fish.	The specific toxins involved are mainly ciguatoxin and maitotoxin.
Scombroid	Microbiologic degradation of histidine to histamine in fish.	Mackerel fish (Mackerel, sardines and tuna).		Allergic reaction. Incubation: 10-90 minutes.	fish should be stored cold (below 10 °C).	The toxin is heat stable.
Amnesic-shellfish-poison (ASP)	Algae (diatom from the Nitzschia pungens species).	Accumulation in shellfish.		Memory loss, sometimes lasting.	Inhibit the growth of algae that can produce toxic components.	The toxin is heat stable. Only on the American and Canadian east coast.
Paralytic-shellfish-poison (PSP) {paralysis}	Algae (dinoflagellate)	Accumulation in shellfish.	500-5000 (humans). 0,3 (mice die after 5-7 minutes)	Toxin blocks nerve transmission Mortality: 1-20%. Incubation: 1-30 min.	Inhibit the growth of algae that can produce toxic components.	The toxin is heat stable. Algae is not located in the Dutch waters yet, although it can grow in temperate climates.
Diarrhetic-shellfish-poison (DSP)	Algae (dinoflagellate).	Accumulation in shellfish.	50 (mild symptoms based on okadaic acid)	Diarrhoea, stomachache, vomiting. Incubation time is between 30 min and several hours.	Inhibit the growth of algae that can produce toxic components.	The toxin is heat stable. Algae is incidentally encountered in Dutch waters.
Neurotoxic-shellfish-poison (NSP)	Algae (dinoflagellate); high concentrations could colour the sea red (red tide).	Accumulation in shellfish.	10 (deadly for mice)	Blocks nerve transmission. Rarely deadly. Incubation time is two minutes to several hours.	Inhibit the growth of algae that can produce toxic components.	The toxin is heat stable and endemic in Subtropical waters.
Biogenic-amine Histamine	Plants, animals and microbes	Almost all food products high in proteins. Histamine is formed from histidine by enzymes mainly from the Enterobacteriaceae.		Influences physiological processes in the body. Consumption of biogenic amines could lead to poisoning. Symptoms: nausea, stuffiness, palpitations, eczema, unnatural blood pressure and headache.		Often present in fish as histamine, a symptom similar to food poisoning.

Fraud: Fish, crustaceans and molluscs

Fraud Status food safety summary
The fish chain lends itself to various forms of fraud. Some examples follow.

• Fish species such as bluefin tuna, cod, and sole can be replaced by fish that are much cheaper. In a filleted state, this can only be found by performing DNA analysis.
• MSC-certified fish offered cannot in reality be MSC-certified fish.
• Improper handling and the use of additives and dyes can make fish appear fresher than it actually is.
• Quotas, which limit the maximum catch of many fish species to prevent overfishing, can be circumvented by keeping caught fish off the books and landing them illegally.
• Weight indications do not have to correspond to reality.

Unfortunately, we have to note that all these forms of fraud occur in the fishing industry. This can affect food safety. The Dutch Food Safety Authority-IOD sees the following forms of fraud: converting, upgrading, and keeping quoted fish out of the books. These forms of fraud are briefly explained below.