Lecture 6: Toxins in Food Flashcards
Toxicology
The study of poisons and more specifically the adverse effects of chemicals on living organisms
Food toxicology
The study of toxic substances in the human food chain
Food poisoning
- Illness from consuming food that contains a harmful substance, harmful microorganism, or toxin produced by a microorganism
- Can result in short-term symptoms, long-term disease and death
Natural contaminants vs. Man-made contaminants
Natural:
-toxins produced by the plant or animal
-normal components of food
Man-Made:
-Chemical (pesticides, cleaning agents, antibiotics, toxins produced during cooking)
-Physical (dead insects, hair, glass, metal)
-Biological (microorganisms like bacteria, viruses, mold, fungi)
How is food toxicology deeply rooted in the history of human civilization?
Our ancestors had to learn through trial and error which foods were harmful and which were safe
Red Emperor Shen Nung
- Father of Chinese traditional medicine
- Noted for tasting 365 herbs
- Discovered tea
- Taught people how to cultivate grains as food –> less reliance on animals
- Wrote “The Great Herbal”
- Died of a toxic dose
Ebers Papyrus
- Oldest, well preserved medical document from ancient Egypt
- Contains a collection of info on anatomy and physiology, toxicology, spells, treatments
Homer (Greek)
Wrote of the use of arrows poisoned with venom in “The Odyssey” and “The Iliad”
Socrates
- Chared with religious heresy and corrupting the morals of local youth
- Committed to death by Hemlock (alkaloid coniine causes paralysis and death when ingested)
Paracelsus
- Father of toxicology
- “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy.”
Mateu J.B. Orfila
- Proficient in the chemistry of crime scene investigation and was an early promoter of chemical evidence in the courtroom
- Founder of forensic toxicology
Toxicity vs. Hazard
- Toxicity = capacity (potency) of a substance to produce injury
- Hazard = probability that injury will result from use of a substance in a prescribed quantity and manner (includes levels of “how much”)
Equation for risk
Risk = exposure x inherent toxicity
How does the FDA protect the U.S. food supply?
- Conducts tests, sets standards, and enforces laws regulating food quality and processing
- Regulate food colors and additives
How does the USDA protect the U.S. food supply?
USDA regulates and inspects meats, poultry, eggs, and dairy
How does the EPA protect the U.S. food supply?
- Responsible for establishing tolerances for pesticide residues in or on foods and feeds
- Tolerances are legal limits of the amount of pesticide residues that can be found on a raw agricultural commodity at the farm gate or in a processed food
List the food hazards in order of concern by regulatory agencies
- Microbial
- Nutritional
- Environmental
- Natural toxicants
- Pesticide residues
- Food additives
According the the CDC, how many people suffer from food borne illnesses each year?
- 48 million suffer
- 128,000 hospitalizations
- More than 3,000 deaths
Dose response curve
- Plot of dose vs. response
- Determines potency of compounds
- Determines how much of a compound we consume
- Estimates risk of compounds
LD50
Lethal dose when 50% of population dies
Acute vs. chronic exposure
- Acute = one dose or exposure over a very short period of time (< 1 week)
- Chronic = multiple doses which occur over an extended period of time (> 1 week)
Acute vs. chronic toxicity
- Acute = lasts a few minutes, hours, weeks
- Chronic = can last months, years, a lifetime
Paralytic shellfish poisoning
- Onset = 30 - 60 mins
- Symptoms = tingling, burning, numbness, drowsiness, incoherent speech, respiratory paralysis
- Duration = respiratory support within 12 hours or exposure results in complete recovery
Dinoflagellates
- Marine phytoplankton responsible for algae blooms (red tides) that occur in the warmer months
- Poduce saxitoxin
Ciguatoxin
- Caused by eating tropical and subtropical fish (barracuda, red snapper, sea bass)
- Obtained from food chain (large carnivorous fish eat small fish that eat algae that have eaten toxic dinoflagellates)
- Not destroyed by cooking
- Has no effect on the host fish (no difference on appearance)
Ciguatera fish poisoning
- Onset = less than 6 hrs
- Symptoms = gastrointestinal (nausea, vomitting, diarrhea); neurological (numbness and tingling around mouth, joint pain, muscle ache, headache, temp sensory reversal, extreme exhaustion)
- Duration = usually goes away on its own within several days; rarely some neurological symptoms may persist for months or years
Tetrodoxin (Fugu)
- Fugu = Japanese delicacy made from puffer fish or blowfish
- Contains a lethal poison called tetrodotoxin in the liver and ovaries
Cyanogenic Glycosides
- About 150 species of plants produce cyanogenic glycoisides
- Release HCN when plant is chewed
- Not toxic by themselves but when a plant is chewed, the glycoside is broken down by an enzyme and HCN is released
- Acts as a defense mechanism to discourage animals from eating it
- Sources = bitter almonds, lima beans, cassava root
Cassava
- Staple food and major carb source in tropical areas
- Starchy roots produce more calories per unit of land than any other crop in the world
How are cyanogenic glycosides removed from cassava in order for it to be eaten?
Roots of cassava are scraped or grated, soaked in water and fermented for a few days
Glycoalkaloids
- Toxins from the plant genus Solanacea (potatoes, tomatoes, eggplant, nightshade)
- Solanine in potatoes can be toxic
Potatoes and solanine
- Solanine is found in the sprouts, right under the peel, and in sun-greened areas of potatoes
- When potatoes are exposed to light, solanine levels can rise to 10x their original value
- Solanine levels in potatoes are associated with a green skin color caused by the formation of chlorophyll
- The greener the potato, the more likely it is that it contains high concentrations of solanine
Green potato poisoning
- Rare
- Poisoning can result form ingestion of potato sprouts, sprouted potatoes, and especially green potatoes
- Symptoms = gastrointestinal upset, headache, fever, convulsions, drowsiness, rapid breathing, delirium, and coma
Polycylic Aromatic Hydrocarbons
- Formed by the incomplete combustion of organic material and occur in the residue of smoke
- ore than 100 distinct PAHs are known
Acrylamide
- Starch-rich foods can contain high levels or acrylamide
- Known carcinogen in rats and a probable carcinogen in humans
- Formed in foods during baking and frying
- Forms when foods rich in asparagine are cooked in temps greater than 248 F
Lanape potato chip
- To make a good potato chip, you need a potato with a high level of starch
- In the 1960s, a group of researchers teamed up with the USDA to breed a high starch potato they named “Lenape” that made great potato chips
- Turned out to be toxic b/c of high solanine levels of the breeding stock
- Recalled ~ 1974
