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food toxicants and analysis > Classes/Sources of Food Toxins > Flashcards

Classes/Sources of Food Toxins Flashcards

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1
Q

A toxicant that was ALREADY present in the food naturally is:

A

endogenous toxin

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2
Q

What is a foodbourne toxicant?

A

A chemical compound in food that causes adverse health effects in consumer

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3
Q

What are the consequences of contaminants in food?

A
  • foodbourne illness
  • adverse reactions (intoxication, allergic reaction)
  • Bans on export/trade
  • damaged reputation of producer
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4
Q

Define “contaminants in food”

A

Substances NOT INTENTIONALLY added, but are present in food
Introduced during production/processing/storage/etc.
(could be at any or several stages)

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5
Q

True/False: rodent hair and insect fragments are considered to be contaminants, under the Codex Alimentarus

A

False

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6
Q

Name the 4 categories of food safety hazards:

A
  • physical
  • chemical
  • microbiological
  • allergens
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7
Q

The 3 main groups of food toxicants:

A

Naturally occuring toxicants
Synthetic toxicants
Endogenous toxicants

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8
Q

If a contaminant has an “adverse effect,” what might if affect in the consumer? (8)

A 
Morphology
Physiology
Growth/Development
Reproduction
Lifespan
Decreased functional capacity
Decreases stress tolerance
Increased susceptibility to other influences
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9
Q

What are some examples of plant and animal endogenous toxins?

A

Plant: Cyanoglycosides, Lectins, Glycoalkaloids

Animal: Estrogens

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10
Q

True/False: synthetic toxins can be intentionally introduced to food.

A

True. (adulteration, food fraud)

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11
Q

What product could potentially lead to cyanide poisoning in large quantities, due to endogenous toxins?

A

Bitter apricot kernels

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12
Q

What is the difference between naturally occuring toxins and endogenous toxins?

A

Endogenous: naturally present in the food itself; require methods to destroy to make food safe, or need to limit consumption

Naturally occurring: From natural sources but should not be present in the edible food itself - presence in food is due to contamination/spoilage

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13
Q

In the recent China milk scandal, what toxin was added to milk, and for what reason?

A

Melamine

To boost apparent protein content (fraud)

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14
Q

3 examples of mycotoxins:

A

Aflatoxins
Ochratoxins
Patulin

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15
Q

What is the cause of paralytic shellfish poisoning?

A

Algal growth -> produces saxitoxin

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16
Q

Naturally occuring toxins may be present from: (4)

A
  • Fungal growth (mycotoxins)
  • Algal growth
  • Bacterial growth
  • Improper preparation (pufferfish tetrodotoxin)
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17
Q

What is the main bacterial toxin of concern?

A

Botulinum toxin (cause botulism)

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18
Q

3 examples of algal toxin:

A

Saxitoxin
Domoic Acid
Brevetoxin

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19
Q

What is the toxin produced in fish by the eukaryote G. toxicus? What does consuming it cause?

A

Ciguatoxin

Ciguatera - nausea, tingling, vomiting (rarely fatal)

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20
Q

To properly identify hazards, you need to know: (2)

A
  1. ADVERSE HEALTH EFFECTS

2. sources of exposure

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21
Q

What are some sources of synthetic toxins? (7)

A
  • Agricultural chemicals
  • Veterinary drugs
  • Environmental contaminants
  • Process contaminants
  • Residues from packaging
  • Cleaning chemicals/biocides
  • Adulterants
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22
Q

What is the first step of risk assessment?

A

Hazard identification

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23
Q

How are adulterants different from other sources of synthetic toxins?

A

Intentionally added (food fraud)

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24
Q

the ____ is expressed as amount of chemical entering the body per body weight.

A

Dose

25
Q

The 3 types of dose-response relationships:

A

threshold
non-threshold
essential nutrients

26
Q

What parameters does the adverse effect of the toxin depend on? (4)

A
  • Dose
  • Duration/frequency of exposure
  • type of food ingested
  • other biological parameters (sensitivity, etc)
27
Q

The amount of a substance per body weight that would cause fatality is the ____.

A

lethal dose

28
Q

What is the key parameter for safety evaluation of chemicals in terms of toxicology?

A

LD50

29
Q

How does the curve for essential nutrients differ from other toxins?

A

certain amount is necessary for life;
at low concentrations, adverse effect is high -> increasing dose will normalize (low harm)
BUT: increasing beyond required amount can cause increasing adverse effects.

so: U SHAPED CURVE

30
Q

Describe the dose-response curves for threshold and non-threshold toxins. What accounts for their differences?

A

Threshold: S shaped curve (gradual increase, then steep slope, then plateau)
Non-threshold: constant slope

Threshold toxins: body has some TOLERANCE and detoxification ability. Lower amounts can be handled, but as dose increases, it overwhelms the detox mechanisms and becomes very harmful (steep slope)

Non-threshold: zero tolerance, even tiny amounts are harmful. (carcinogens, etc)

31
Q

How is the dose-response curve established?

A

Animal tests
Feed increasing doses to animals, observe death rate (or rate of certain effect)
curve is dose vs % death (or effect)

32
Q

A lower LD50 corresponds to (higher/lower) toxicity.

A

higher

33
Q

What is the ED50?

A

Effective Dose

Dose that causes adverse effect in 50% of test animal population

34
Q

Although today there is no distinction made between solid and liquid forms of toxins, which was previously classified as being more toxic and why?

A

Liquid; easier absorption/higher bioavailability -> lower LD50

35
Q

If the adverse effect observed is death, then the median lethal dose is known as?

A

LD50

36
Q

_____, found in bbq foods, is a class 1 carcinogen and classified as a _____.

A

benzopyrenes; genotoxin

37
Q

Do LOAEL or NOAEL exist for genotoxins?

A

No; even tiny amounts will cause adverse effects (non threshold)

38
Q

What are the WHO classes of pesticides (according to hazard level)?

A

Ia: extremely
Ib: highly
II: moderately
III: slightly

39
Q

How are NOAEL/LOAEL determined?

A

Experimentally

40
Q

What is NOAEL?

A

no observed adverse effect level

- point just below LOAEL, highest dose without adverse effects.

41
Q

LOAEL and NOAEL only apply for ____ curves.

A

Threshold

42
Q

True/False: for some heavy metals, too low of an exposure will have adverse effects.

A

True

Cu, Ni, Fe, Zn are all essential in the body at low levels; deficiency will cause disease

43
Q

What is the LOAEL?

A

lowest observed adverse effect level

- first point on curve that is SIGNIFICANTLY DIFFERENT from control

44
Q

Acute exposure is ______, while chronic exposure is ______.

A

acute: exposure within 24 hrs
chronic: AVERAGE daily exposure over several years to a lifetime

45
Q

What are amygdalin and linamarin? Are they toxic?

A

cyanogenic glycosides

No; but breakdown will yield toxic cyanide

46
Q

What might cause copper deficiency or excess?

A

Deficiency: Increased uptake of zinc, absorbance issues. (rarely due to diet)
Excess: acidic food leeching from copper container

47
Q

Food toxicants have a wide range of:

A

physicochemical properties

48
Q

Give an example of acute exposure, and of chronic exposure in the modern day food industry

A

Acute: Clenbuterol (vet drug) in Spain/Portugal - contaminated lamb/beef - cause tremors/tachycardia/nausea/dizziness

Chronic: Methylmercury - Minamata, Japan - in fish (bioaccumulative effect) - lead to Minamata disease (neurological effects, fetal defects)

49
Q

“small” molecules are typically below _____. These are mostly ____ contaminants.

A

900Da

organic

50
Q

What are some physicochemical properties? (5)

A 
Size
Structure
Behavior as acid/base
Polarity
Volatility
51
Q

The physicochemical properties of a chemical have implications in its: (2)

A

behaviour/stability (in food and in body system)

analytical methods

52
Q

What are the larger sized contaminants?

A

Proteins

53
Q

What are some nonpolar contaminants?

A

PCBs, DDT, chlordanes, oil residues

54
Q

A highly volatile substance has a ____

A

high vapor pressure/low boil pt

55
Q

Compounds may be classified as: (according to volatility)

A

nonvolatile
semi volatile
volatile

56
Q

Most pesticides and antibiotics are (polar/nonpolar); so they are soluble in:

A

polar

water, protic organic solvents

57
Q

What makes a compound an acid/base?

A

presence of IONIZABLE groups; charged by presence of acid/base

58
Q

compounds with ionizable groups will have multiple ____ that change depending on ____.

A

forms

pH

food toxicants and analysis (11 decks)

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