Classes/Sources of Food Toxins Flashcards
A toxicant that was ALREADY present in the food naturally is:
endogenous toxin
What is a foodbourne toxicant?
A chemical compound in food that causes adverse health effects in consumer
What are the consequences of contaminants in food?
- foodbourne illness
- adverse reactions (intoxication, allergic reaction)
- Bans on export/trade
- damaged reputation of producer
Define “contaminants in food”
Substances NOT INTENTIONALLY added, but are present in food
Introduced during production/processing/storage/etc.
(could be at any or several stages)
True/False: rodent hair and insect fragments are considered to be contaminants, under the Codex Alimentarus
False
Name the 4 categories of food safety hazards:
- physical
- chemical
- microbiological
- allergens
The 3 main groups of food toxicants:
Naturally occuring toxicants
Synthetic toxicants
Endogenous toxicants
If a contaminant has an “adverse effect,” what might if affect in the consumer? (8)
Morphology Physiology Growth/Development Reproduction Lifespan Decreased functional capacity Decreases stress tolerance Increased susceptibility to other influences
What are some examples of plant and animal endogenous toxins?
Plant: Cyanoglycosides, Lectins, Glycoalkaloids
Animal: Estrogens
True/False: synthetic toxins can be intentionally introduced to food.
True. (adulteration, food fraud)
What product could potentially lead to cyanide poisoning in large quantities, due to endogenous toxins?
Bitter apricot kernels
What is the difference between naturally occuring toxins and endogenous toxins?
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
In the recent China milk scandal, what toxin was added to milk, and for what reason?
Melamine
To boost apparent protein content (fraud)
3 examples of mycotoxins:
Aflatoxins
Ochratoxins
Patulin
What is the cause of paralytic shellfish poisoning?
Algal growth -> produces saxitoxin
Naturally occuring toxins may be present from: (4)
- Fungal growth (mycotoxins)
- Algal growth
- Bacterial growth
- Improper preparation (pufferfish tetrodotoxin)
What is the main bacterial toxin of concern?
Botulinum toxin (cause botulism)
3 examples of algal toxin:
Saxitoxin
Domoic Acid
Brevetoxin
What is the toxin produced in fish by the eukaryote G. toxicus? What does consuming it cause?
Ciguatoxin
Ciguatera - nausea, tingling, vomiting (rarely fatal)
To properly identify hazards, you need to know: (2)
- ADVERSE HEALTH EFFECTS
2. sources of exposure
What are some sources of synthetic toxins? (7)
- Agricultural chemicals
- Veterinary drugs
- Environmental contaminants
- Process contaminants
- Residues from packaging
- Cleaning chemicals/biocides
- Adulterants
What is the first step of risk assessment?
Hazard identification
How are adulterants different from other sources of synthetic toxins?
Intentionally added (food fraud)
the ____ is expressed as amount of chemical entering the body per body weight.
Dose
The 3 types of dose-response relationships:
threshold
non-threshold
essential nutrients
What parameters does the adverse effect of the toxin depend on? (4)
- Dose
- Duration/frequency of exposure
- type of food ingested
- other biological parameters (sensitivity, etc)
The amount of a substance per body weight that would cause fatality is the ____.
lethal dose
What is the key parameter for safety evaluation of chemicals in terms of toxicology?
LD50
How does the curve for essential nutrients differ from other toxins?
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
Describe the dose-response curves for threshold and non-threshold toxins. What accounts for their differences?
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)
How is the dose-response curve established?
Animal tests
Feed increasing doses to animals, observe death rate (or rate of certain effect)
curve is dose vs % death (or effect)
A lower LD50 corresponds to (higher/lower) toxicity.
higher
What is the ED50?
Effective Dose
Dose that causes adverse effect in 50% of test animal population
Although today there is no distinction made between solid and liquid forms of toxins, which was previously classified as being more toxic and why?
Liquid; easier absorption/higher bioavailability -> lower LD50
If the adverse effect observed is death, then the median lethal dose is known as?
LD50
_____, found in bbq foods, is a class 1 carcinogen and classified as a _____.
benzopyrenes; genotoxin
Do LOAEL or NOAEL exist for genotoxins?
No; even tiny amounts will cause adverse effects (non threshold)
What are the WHO classes of pesticides (according to hazard level)?
Ia: extremely
Ib: highly
II: moderately
III: slightly
How are NOAEL/LOAEL determined?
Experimentally
What is NOAEL?
no observed adverse effect level
- point just below LOAEL, highest dose without adverse effects.
LOAEL and NOAEL only apply for ____ curves.
Threshold
True/False: for some heavy metals, too low of an exposure will have adverse effects.
True
Cu, Ni, Fe, Zn are all essential in the body at low levels; deficiency will cause disease
What is the LOAEL?
lowest observed adverse effect level
- first point on curve that is SIGNIFICANTLY DIFFERENT from control
Acute exposure is ______, while chronic exposure is ______.
acute: exposure within 24 hrs
chronic: AVERAGE daily exposure over several years to a lifetime
What are amygdalin and linamarin? Are they toxic?
cyanogenic glycosides
No; but breakdown will yield toxic cyanide
What might cause copper deficiency or excess?
Deficiency: Increased uptake of zinc, absorbance issues. (rarely due to diet)
Excess: acidic food leeching from copper container
Food toxicants have a wide range of:
physicochemical properties
Give an example of acute exposure, and of chronic exposure in the modern day food industry
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)
“small” molecules are typically below _____. These are mostly ____ contaminants.
900Da
organic
What are some physicochemical properties? (5)
Size Structure Behavior as acid/base Polarity Volatility
The physicochemical properties of a chemical have implications in its: (2)
behaviour/stability (in food and in body system)
analytical methods
What are the larger sized contaminants?
Proteins
What are some nonpolar contaminants?
PCBs, DDT, chlordanes, oil residues
A highly volatile substance has a ____
high vapor pressure/low boil pt
Compounds may be classified as: (according to volatility)
nonvolatile
semi volatile
volatile
Most pesticides and antibiotics are (polar/nonpolar); so they are soluble in:
polar
water, protic organic solvents
What makes a compound an acid/base?
presence of IONIZABLE groups; charged by presence of acid/base
compounds with ionizable groups will have multiple ____ that change depending on ____.
forms
pH
