Lecture 15: Food Toxicology Flashcards by Zoe Phillips

T/F: Food is produced globally, so strict quality control is difficult

true

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what are the two things food contain?

nitrients (carbs, proteins, lipids, vitamins/minerals)
non-nutrient substances

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The Food, Drug and Cosmetics Act (USA) presumes that food is safe
if it is free of certain contaminants, how are foods banned?

needs to be clear evidence that death or
illness can result from consuming it

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T/F: Anything can be added to food if it falls into a class called
‘Generally Recognized As Safe (GRAS)’

true!!

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Many different types of toxins can be in
our food, leading to: (4)

fish and shellfish poisoning
meat poisoning
mycotoxins
botulism

(symptoms are severe and acute, so easy to treat!)

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Certified colour additives have the prefix ______

FD&C

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T/F: Natural additives do not need certification (animal or plant base)

true

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______ can be produced by aquatic phytoplankton

Toxins

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Different diatoms & dinoflagellates can
produce different ______

toxins

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how do humans normally get poisoned by shellfish?

humans normally get poisoned by eating
shellfish that have filtered these organisms (phytoplankton) from the water and accumulated the toxin

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what are diatoms?

photosynthetic
organisms with a cell
wall made of
transparent silica

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what causes red tides in water?

blooms of dinoflagellates, Karenia brevis

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how are harmful algal blooms (increasing in biomass) such a big issue near cities?

nutrients being put into water, lots near big populated cities! (point and non-point sources)

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__________:
Most common and severe type of shellfish poisoning
- Most severe outcomes in children
- Most often from eating clams or mussels
Caused by dinoflagellates that produce saxitoxin(s)
– Blocks Na+ channels keeping them closed (opposite from DDT/pyrethroids)
- Can lead to flaccid paralysis (instead of rigid paralysis)
Symptoms: tingling and numbness of face and limbs, vomiting and
diarrhea, mental status changes and respiratory failure – symptoms
appear 30-60 mins after ingestion

Paralytic Shellfish Poisoning

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what organisms produce saxitoxins? what type of poisoning does this cause?

dinoflagellates
paralytic shellfish poisoning

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__________
– From various brevotoxins made by
the dinoflagellate Karenia brevis
- most well known “red tide”
– Also blocks Na+ channels, but not as
severe outcomes as PSP
– Can also get exposed by inhaling
aerosolized sea spray!
Symptoms: Usually gastroenteritis with neurological
symptoms – symptoms appear 30-180 mins after
ingestion

Neurotoxic Shellfish Poisoning

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what type of organism produces brevotoxins? what illness does this produce?

dinoflagellate
neurotoxic shellfish poisoning

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__________
Caused by okadaic acids produced by some algae
(Dinophysis and Prorocentrum spp.).
- Most cases from eating mussels and scallops.
Symptoms: abdominal pain, diarrhea, vomiting within 2
hrs of ingestion. Symptoms gone in 2-3 days, no deaths
reported.

Diarrheic shellfish poisoning
(doesn’t involve sodium channels!!)

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what type of organism produces okadaic acids? what illness does it cause?

algae (dinophysis and prorocentrum)
causes diarrheic shellfish poisoning

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___________
Domoic acid is produced by the diatom Pseudo-nitzschia spp.
- Relatively rare form of shellfish poisoning
Symptoms: abdominal pain, diarrhea, vomiting within 24hrs
of ingestion followed by headache, cognitive impairment and
memory loss.
Binds to excitatory amino acid receptors in neurons,
causing Ca2+ influx in nerve cells.

1987 outbreak in PEI: 156 cases, 3 deaths, 12 with permanent short-term memory loss

Amnesic shellfish poisoning
(affecting sea lions along coast right now! more and more common as we’re adding more nutrients to the water on the coast)

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_________ is produced by the diatom Pseudo-nitzschia spp.

causes what illness?

Domoic acid
amnesic shellfish poisoning

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where was the largest recorded outbreak of domoic acid?

Along the North
American west coast
in 2015

Possibly linked to a
large-scale ocean
temperature anomaly
“the blob” (super high temp water region was traveling through ocean) and nutrient
enrichment along the
coast. Huge spike in diatom that produces domoic acid

closure of shellfish/finfish fisheries to protect human health, many marine mammals showed signs of domoic acid poisoning (sea lions are accumulating the highest levels for some reason, most poisoned)

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_______: toxin-producing cyanobacteria, often found in Lake
Winnipeg

blue-green algae

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when ______ is limited in the water, blue-green algae out-
compete green algae and lead to harmful algal blooms.

nitrogen

Green algae (plants) uptake N and P
Blue-green algae (bacteria) fix their own N

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the blue-green algae Microcystis spp. make a class of 80 different toxins called _______ that are liver toxins! (This is very toxic to dogs, issue at Lake Winnipeg)

microcystins

what do microcystins do?

inhibit the activity of protein phosphatases that remove phosphate groups from proteins that are necessary for their regulation. In the liver, this can affect glucose metabolism.

_____ or maitotoxin produced by Gambierdiscus toxicus (a dinoflagellate that grows on and around coral reefs)

Ciguatoxin

_______: Biomagnifies Humans exposed when they eat contaminated reef fish. Toxins are concentrated in fish liver, intestines, roe, and heads. Symptoms: cardiovascular, gastrointestinal, neurologic, and neuropsychiatric illness develops within 3–6 hours

ciguatera

_________: Named for the family Scomberidae (tunas, mahi mahi, bluefish, sardines, marlin, mackerels) * Can involve any fish containing high levels of free histidine. * Improper storage allows bacteria to break down free histidine into histamine. symptoms resemble an acute allergic reaction with 10-60 mins of ingestion. Antidote is antihistamines! Symptoms: abdominal cramps and diarrhea, blurred vision and flushing of the face and upper body (resembling a sunburn), headaches. Usually resolve within 12–48 hrs. A cluster of cases helps exclude true fish allergies.

Scombroid poisoning

________: Pufferfish accumulate _____ in (mostly) their liver and gonads. potent Na+ channel blocker (neurotoxin) Symptoms: paralysis of muscles including respiratory tract. Can lead to death due to respiratory failure within 20 min to 24 hrs

Tetrodotoxin

_____ can also be found in: parrot fish * Taiwanese guppies * arrow poison frogs (Atelopus in Costa Rica) * the blue-ringed octopus (Australia) * certain Japanese mussels * sea snails * starfish * a few types of Philippine crabs * California newt (taricha torosa).

tetrodotoxin

T/F: Pufferfishes are resistant to tetrodotoxin (TTX) that they accumulate primarily through their diet.

true!!

how are pufferfishes resistant to TTX?

Due to amino acid substitutions in their Nav 1.4 channel (voltage-gated Na+ channel) Benefits: deter predators, can also eat contaminated prey, may be used to attract mates

T/F: Nitrite as an additive creates carcinogenic compounds

true!!!

Nitrite (NO₂− ) is used in curing meat and fish products. * Antimicrobial activity, sensory attributes, reacts with myoglobin and hemoglobin to form red nitrosylcompounds. * Nitrite reacts with 2º, 3º amines to form stable _________. * High temperature (i.e. cooking) and acidic conditions (i.e. digestion) increase the rate of _______ formation.

nitrosamines

_______ can lead to DNA adducts and increase risk of cancer

Nitrosamines

In _____, the WHO upgraded cured meats to Group 1 carcinogens

2015

The high temperature breakdown of carbohydrates and proteins when grilling and smoking meats can form _____ and heterocyclic aromatic amines (HAAs). Which can also form DNA adducts

PAHs All meat is now considered to be a Group 2A human carcinogen. Higher incidence of stomach and colorectal cancers in heavy meat eaters.

______ are toxins produced by fungi

Mycotoxins

300 known _______, 30 (10%) are well-characterized * A single species of fungus may make several toxins. * Several species of fungi can make the same toxin. * Often, only particular strains of a species will make toxins. * High infection rates on drought-stressed and insect-eaten plants. * High fungal growth rates when food is stored at high humidity.

mycotoxins

T/F: Mycotoxins can also be passed from animals we consume to humans

true!!

T/F: Up to 25% of all food produced globally are contaminated to some degree by mycotoxins!

true!!

_______: Affects cereals, figs, oilseeds, nuts, tobacco, and a long list of other commodities acute toxicity in humans rare. Human acute symptoms include abdominal pain, pulmonary edema, and fatty liver and necrosis of the liver

aflatoxins

______: these are modified furanocoumarins that are made via fungal polyketide biosynthesis. There are four ‘major’ ______: B1, B2, G1, and G2 (difference between 1 & 2, 2 is missing double bond) They can be extremely toxic.

aflatoxins

T/F: Aflatoxin content can get really high in some crops!!

true! North America and Europe monitor aflatoxin levels in harvested crops. Limits are set to 20 ppb for human consumption… 300 ppb for animal feed.

Bt corn has reduced levels of aflatoxin contamination, why?

they don't get as much fungal growth!! A GMO corn that express protein normally made by the soil bacteria - Including endotoxins - This makes the corn resistant to some insects - Bt corn was developed to increase yields by reducing insect damage - Decrease in insect damage leads to less fungal infestation, resulting in reduced aflatoxin levels

_______: Caused by eating grains infected by the fungus Claviceps purpurea Grows in wet and overwintered grains: rye, barley, wheat The fungus makes sclerotia or “ergots” by consuming a whole seed and replacing it with fungal hyphae. These float in water… so are easily separated out because rye and barley grains sink!

ergotism

what species produces domoic acid?

diatom, Pseudo-nitzschia

Ergotism is caused by _______

ergot alkaloids

________ - potent vasoconstrictor - 5HT1a agonist (hallucinogenic) - Used to facilitate the delivery of the placenta and stop bleeding in childbirth - WHO ‘essential drug’

Ergometrine

_______ * a potent vasoconstrictor * Used medically to treat migraine headaches

Ergotamine

what are the symptoms and outcomes of ergotism?

1. Gangrene Not enough blood flow to the extremities 2. Convulsions From disruption in serotonin levels 3. Hallucinations From disrupting certain neuro receptors 4. Spontaneous abortions Not enough blood flow to the developing child Not all outbreaks exhibit all these symptoms… likely differences in the alkaloid profiles in different C. purpuria strains

what are the three types of bacterial borne food toxins?

exotoxins endotoxins botulism

_______ Toxins that are made and secreted by bacteria, but can also be released by lysis of the bacteria. - Proteins with enzymatic function. - Partially degraded by cooking. - Can be made by bacteria in contaminated food and persist even after the bacteria is dead

Exotoxins

_______ Cell-associated substances that are structural lipopolysaccharide components of the outer membrane of Gram-negative bacteria. - Released from dead bacteria. - Causes a hyperactive immune response “toxic shock syndrome”: fever, blood clots, hypotension, shock, death

Endotoxins

________: Caused by the exotoxin botulinum (Botulinum Neurotoxin A – BnNT A) produced by the bacteria Clostridium botulinum * Outbreak of _____ in Belgium 1895 revealed the cause as neuroparalytic toxin produced by anaerobic bacterium. * Treatment: Injection of anti-botulinum toxin antibodies.

botulism

_______: forms spores Ubiquitous in the environment * Resistant to heat, light, drying and radiation * Specific conditions for germination * Anaerobic conditions * Warmth (10-50oC) * Mild alkalinity

C. botulinum

C. Botulinum spores contaminates food, and if canned will germinate and make the exotoxin. how can we visually tell if a can/container might have spores within it?

Puffy cans = bad! Avoid even dented cans!

what are the three types of botulism?

food borne infant wound

______ botulism * Botulism spores infect food in anaerobic conditions * Toxin is produced and released into food * Toxin concentration can be reduced through cooking

food borne

______ botulism * Infants ingest C. botulinum spores * Spores germinate in gut and bacterial colony is established, since infant gut bacteria is not thoroughly developed yet * Bacteria colony releases toxins * Can get this from certain foods (especially honey and corn syrup)

Infant

_____ botulism * Mostly associated with IV drug use

Wound

All three types of botulism can impair neuron function. (frem cleaving SNARE proteins) Symptoms include: - Blurred vision, drooping eyelids. - Difficulty swallowing, muscle weakness. - Flaccid paralysis. - Death due to respiratory failure. how would we treat these symptoms?

Treatment: Inject anti-toxin antibodies and put the patient on a ventilator.

what are the medical uses of botulinum toxin? (i.e. botox)

Used to treat conditions when muscles contract when they should not. Blocks the nerve transmission that causes the muscle cells to contract. Used to treat: * Migraine headaches * Back pain * Multiple sclerosis spasms * Excessive sweating

Exotoxins in E. coli Most E. coli strains are non-pathogenic Can be passed from animal to animal through feces. E. coli O157:H7 is a strain that can make _________. O157:H7 strain asymptomatically grows in cow guts. Contaminated hamburger meat and produce are the most common exposure routes for humans. (hamburger disease!!) - Poop contamination!

shiga toxin

when was there a REALLY bad outbreak of O157:H7 (hamburger disease)?

In 1993, there was a really bad outbreak of O157:H7 poisonings in the USA. * 732 infected (mostly kids) * 10 died * 178 with permanent nerve and kidney damage

describe the shiga toxin structure and function, produced by E Coli O157:H7

alpha (a) subunit The toxic catalytic bit. Cleaves the 28S ribosomal RNA, destroying ribosomes and halting all protein translation. beta (b) subunit * Interacts with a specific lipid cell membranes (which cows don’t have!) * Cells take it in by endocytosis. (similar to C. botulinum) primarily occurs in intestinal epithelial cells, causing acute hemorrhagic diarrhea and fever. Often resolves in 10 days.

In kids under 5, the elderly and immunocompromised people, the infection from ________ can spread and cause Hemolytic-uremic syndrome * Direct destruction of kidney cells from toxin * Direct nerve damage * Indirect destruction of red blood cells

shiga toxin

T/F: Most E. coli strains are non-pathogenic

true!!

Lecture 15: Food Toxicology Flashcards

(69 cards)