FNH 200 Lesson 12: Toxicants in food and foodborne disease
Bacterial toxins
A naturally occuring contaminants as toxicants
Seafood toxins
A naturally occuring contaminants as toxicants. Includes histamine, saxitoxin, domoic acid, and tetrodotoxin.
Listeria
A food infection, found in refrigerated smoked fish, raw/unpasteurized milk. Symptoms includes fever, nausea, cramps, may have up to 70 days incubation period after being exposed. Can cause miscarriage or stillbirth. Is prevented by heat/irradiation and hygiene control.
Cholinesterase inhibitors (solanine)
A naturally occurring constituents as toxicants. Inhibits action of enzyme cholinesterase which is in charge of secretion of cholin needed for nerve transmission/impulses, inhibition causes neurological/GI disorders where there is muscle contraction but no muscle relaxation. Found naturally in potatoes (mainly on skin in low amounts). In sunlight, potatoes turn green and will produce a lot of solanine. Solanine is insoluble in water (cannot be removed by washing nor cooking) and 'green' potatoes can be save by peeling of skin. Must destroy green potatoes or peel skin.
Cyanogenic glycosides
A naturally occurring constituents as toxicants. Toxin is hydrogen cyanide that can be produced. Amygdalin (bitter almonds) and linamarin (lima beans) are able to release hydrogen cyanide which is the toxicant. However, if enzymatic activity does not occur, hydrogen cyanide does not form. Low hazard from accidental consumption of fruit seeds by hazardous if lima beans are part of diet.
Mycotoxins
A naturally occurring contaminants as toxicants. Includes ergotism alkaloid and aflaoxins. Produced by mould. Contains vaso-constricting alkaloids that may cause hallucinations. Aflatoxins can be found in mould of peanuts, corn, wheat, rice and is highly toxic/potentially carcinogenic causing liver cancer
Norovirus
A virus that can be found in raw shellfish, any food touched by infected person. Symptoms includes diarrhea, vomiting. Prevented by heat and hygeine.
Toxicity
Ability of a chemical to damage a biological system, substances vary in toxicity and varies in sensitivity among individuals. Measured by LD50 which measures short term poisoning (lower the LD50= stronger the toxicity, LD50 or 50ppm/kg or lower= poison)
Clostridium botulinum
An example of food intoxication and is found in low acid food, anaerobic conditions. Symptoms includes double vision, dry mouth and paralysis. Vegetative cells are easily killed by heat but spores are heat resistant (must do "botulinum cook"= 12D to destroy 10^12 spores), refrigeration.
Staphylococcus aureus
An example of food intoxication found contaminated and undercooked food exposed to open wounds/nasal fluid. Symptoms includes rapid onset of nausea, vomiting, abdominal pain and cramps. Can be prevented by inactivation of heat, cook food well, and refrigerated temperatures, basic hygiene.
What are some microbial contaminant and toxicants?
Campylobacter, shigella, e.coli, salmonella, listeria
What are the 4 safe food handling practices?
Clean: hands, utensils, cooking surfaces (sanitize with mild bleach solution) Separate: avoid cross contamination (separate raw and cooked food) Cook: prepare foods quickly and cook them thoroughly and serve immediately Chill: refrigerate or freeze leftovers within two hours Temperature danger zone: 4-60 degrees, MUST AVOID THIS ZONE
Toxicant
Derived from latin word 'toxicum'= poison. Has whole spectrum of effects from minor effects to death causing.
Viruses
Do not multiply in food but can utilize food as a medium to infect host. Examples includes hepatitis A and norovirus. Van be inactivated by heating and hygiene practices.
HACCP
Hazard analysis and critical control points: system designed to anticipate and control problems before they happen
Domoic acid
Domoic acid: an amnesic shellfish poisoning first discovered from blue mussels, toxin produced by plankton and causes permanent memory loss as neurotoxin causes lesions in nervous system.
Salmonella
Example of food infection, found in raw/undercooked poultry, eggs, beef, milk/dairy products. Symptoms includes, chills, cramps, vomiting. Can be prevented by heat/irradiation, hygiene.
E.col
Example of food intoxication. Found in undercooked beef, unpasteurized milk, acid tolerant= able to survive in acidic foods (apple juice). Symptoms includes bloody diarrhea which may lead to kidney failure. Prevention can be done through heating/irradiation to inactivate it, cooking beef well, refrigeration and basic hygiene.
Where can environmental toxicants be found?
Food packaging residues (monomers of plastic resins), pesticide residues, heavy metals (lead, mercury, cadmium), animal drugs (antibiotics, hormones), radioisotopes
Histamine
Histamine: produced in high levels by bacterial action on fish flesh. Histidine is naturally occuring amino acid high in scombroid fish (tuna, bonito, mackerel) and bacteria converts histidine into histamine which is a toxin that causes allergic reactions like nausea, vomitting, facial flush, itchiness. Effects subsides within 12 hours, mild symptoms.
What are the factors in foodborne disease?
Inadequate cooling of foods, preparation of food several hours in advance, poor personal hygiene/cross contamination, insufficient cooking/reheating of foods, improper hot storage
Incident, outbreak and outbreak of unknown etiology
Incident: simple occurrence of foodborne illness Outbreak: 2 or more people after ingestion of same food with epidemiological evidence (can identify source) Outbreak of unknown etiology: no epidemiological evidence
Food intoxication vs food infection
Intoxication: toxins/toxicants responsible, produced in foods as by products of microorganisms, plants or animals Infection: multiplication of pathogenic microorganisms responsible. Viable microorganisms in food at time of consumption which leads to growth in host to cause illness
Naturally occurring toxicants vs. environmentally occurring toxicants
Naturally occurring: constituents (from food) or contaminants (added/becomes part of food) Environmentally occurring: human activities are responsible for them being in out food supplu
Why are only some FBD outbreaks documented?
Only 1-4% cases are reported because most patients are mistakenly diagnosed as "24-hour flu" or "overeating", also not enough evidence to track back to source.
What may be some sources of foodborne dieseases?
Parasitic, plant, animal, chemical and microbiological (food/waterborne diseases)
Hazard
Probability that injury will result from use of a chemical at a given exposure. Hazard assesed by: inherent capacity to cause harm (toxicity) and the probability of contact between substance and target object
What are some examples of naturally occurring toxicants?
Protease inhibitors (raw soy beans), nitrates (green leafy plants), allergens (peanut proteins, soy proteins)
Saxitoxin
Saxitoxin: is paralytic shellfish poisoning caused by shellfish (mussels, clams, oysters), shellfish are filtering organisms that absorbs toxin and concentrate in tissue, toxin produced by dinoflagellates and found in plankton responsible for red tides which is caused by blooming of plankton. May cause muscular/nerve paralysis.
Why are burgers a concern but not rare/blue steak?
Since burgers are mixed together, microorganisms may be hidden in the middle/core of patty. Whereas steak, the microorganisms are on the surface.
Strychnine and boric acid
StrychnineL extremely toxic in small amounts, when sealed in un-openable vial= no chance of poisoning can occur, no contact can be established between chemical and people Boric acid: mild acid used as antiseptic, insecticide, flame retardant, used as preservative/firming agent in some cultures, not highly toxic but can be very hazardous when used in manner that makes it accessible to accidental ingestion
Tetrodotoxin
Tetrodotoxin: fugu poisoning, produced by bacteria associated with ovaries, liver, skin of puffer fish. Symptoms includes tingling sensations, loss of pupil/cornea reflexes and may lead to paralysis/death. Pufferfish must be handled by professional to degut/deskin them.