Toxicology Chapter 14 (Principles of food toxicology)

impact

-5% of all food-borne outbreaks reported and 37% of all seafood related food-borne illnesses -approx. 200 outbreaks involving 1400 people from 1973-87 -between 1988-1997, 145 reported outbreaks involved 811 persons in 20 states -most in HI, FL, CA, WA, NY, CT

DSHEA & supplements

-DSHEA assigns responsibility to manufacturer for insuring safety and proper labeling. If documentation of reasonable expectation of safety exists as information from prior usage, no formal tax testing required -examples of recent FDA actions: -April 2001- better business bureau referring Arizona Rx memory mind elixir to FDA for violating DSHEA labeling requirements -contains ginkgo biloba & paan ginseng (decaffenated) -NTP-testing aloe vera, ginseng, kava kava and milk thistle nominated by national cancer institute -recent warnings for ephedrine & aristolochic acid -June 2008- amendment to DHSEA GMP for dietary supplements

why PAHs are bad

-PAHs are a concern because they are persistent -because they do not burn very easily, they can stay in the environment for long periods of time -individual PAHs vary in behavior. some can turn into a vapor in the air very easily. most do not break down easily in water

polycyclic aromatic hydrocarbons (PAHs)

-PAHs are chemicals consisting of fused aromatic rings -PAHs are formed during incomplete combustion of organic materials like wood, coal or oil due to decomposition (pyrolysis) reactions -PAHs enter the air mostly as releases from volcanoes, forest fires, burning coal, and automobile exhaust -we are most likely to be exposed to PAH vapors or PAHs that are attached to dust and other particles in the air -sources include cigarette smoke, vehicle, exhausts, asphalt roads, coal

note

-PCBs are no longer manufactured or widely used today. pcbs can be highly concentrated in the fish of waters contaminated with even low levels of PCBs. predator fish at the top of the food chain, as well as bottom feeding fish, tend to contain the highest PCB levels in those waters -benzoapyrene is a polycyclic aromatic hydrocarbon found in coal tar. the main source of atmospheric benzopyrene is residential wood burning. in food, PAHs may be formed during processing and domestic food preparation, such as barbecuing, smoking, drying, roasting, baking, frying or grilling

do organic foods have less arsenic than non-organic foods

-because arsenic is naturally found in the soil and water, it is absorbed by plants regardless of whether they are grown conventional or organic farming practices

mushroom myths

-a mushroom is safe to eat if it does not turn a silver spoon black when boiled together -no deadly mushrooms grow on wood -if an animal eats it, the mushroom is safe -boiling, drying, and salting will detoxify the mushroom -poisonous mushrooms will turn rice-water red -mushrooms are safe, toadstools are poisonous -a mushroom is safe to eat if the cap has been peeled

birth defects

-a study in Minnesota found significantly higher rates of birth defects in children born to pesticide applicators and in regions of the state where chlorophenoxy herbicides and fungicides are widely used (Garry, 1996) -in california, mothers living and working in agricultural areas with high pesticide use had a higher risk for giving birth to children with limb reduction defects (Schwartz, 1988) -a study of pregnant women in Iowa and Michigan found that women exposed to multiple pesticides had an increased risk of giving birth to a child with cleft palate (gordon, 1981)

is there a risk from eating foods that contain acrylamide

-acrylamide caused cancer in animals in studies where animals were exposed to acrylamide at very high doses -in 2010, the joint food and agriculture organization/world health organization expert committee on food additives (JECFA) concluded that acrylamide is a human health concern, and suggested additional long-term studies

the exposure for specific duration and frequency decides toxic effect

-acute exposure: since (or frequent) exposure to toxic doses for short time equal to or less than 24 hours, subacute exposure during 1 month, sub chromic exposure during 1-3 months, highly potent toxicants may be involved -chronic exposure: exposure to small doses for long time, greater than 3 months of lifespan, contaminants of food, air, water

algal toxins

-algae are most prominent in aquatic environments, they are photosynthetic, eukaryotic, unicellular to macroscopic, multicellular structures -approx. 5000 species of algae are known, and about 40 species, mostly the dinoflagellates, produce secondary metabolites that also act as potent toxins

note

-all these branches of toxicology rely on the same basic science to achieve their goals, and are not all mutually exclusive. for example, poisoning at the workplace would encompass aspects of both clinical and occupational toxicology -majority of these branches from basis of areas of toxicology such as food toxicology, nanotoxicology, toxicogenomics. in food tox. in particular, we study about toxic effects of certain bioactive substances occurring in foods. it deals about certain food additives causing harmful health effects when consumed in excess

toxicity of PAHs

-although unmetabolized PAHs can have toxic effects, the major concern in animals is the ability of reactive metabolites to bind to proteins and DNA -four, five and six ring PAHs have greater carcinogenic potential than do two, three or seven ring PAHs -the addition of alkyl groups to PAHs enhances the carcinogenic potential of these compounds -breathing or touching mixtures of PAHs and other chemicals for long periods of time have developed cancer -some PAHs have caused cancer in laboratory animals when they breathed air containing them (lung cancer), ingested them in food (stomach cancer), or had them applied to their skin (skin cancer)

how to prevent seafood poisoning

-always keep seafood refrigerated or on ice, if you have a weak immune system, you should consider not eating raw seafood (avoid) -refrigerate fresh tuna, mackerel, grouper and mahimahi (cooking does not destroy the toxins in spoiled or toxic seafood) -check with health officials about local advisories on algae blooms, dinoflagellate growth, or red tide -do not eat fish or shellfish sold as bait, these products do not have to meet the same standards as seafood for eating

scombrotoxic fish poisoning

-amberjack, mackerels, sardines, mahi-mahi mahi-mahi, tunas -occurs when people eat fish that were improperly handled (temp. abused) and permitted to build up biogenic amines (histamine, cadaverine, and putrescine) as a consequence of bacterial spoilage -mainly involves any fish containing high levels of free histidine -bacteria break down free histidine into histamine -it is one of the three most common causes of food borne illnesses associated with the consumption of seafood

diatom

-amnesic shellfish poisoning (ASP)

domoic acid group

-amnesic shellfish/syndromes (ASP) -molluscan shellfish harvested from US northwest and northeast coast -toxin-producing algae are found in gulf of Mexico -toxins found in viscera of several crab species and anchovies from US -the toxin is concentrated in shellfish such as mussels and causes disease when the contaminated shellfish are eaten -causes symptoms within 24 hours. symptoms include an upset stomach, dizziness, headache, disorientation, and short-term memory loss. seizures may occur in severe cases

arsenic

-arsenic is an element that occurs naturally in rocks and soil -in the environment, arsenic is combined with oxygen, chlorine, and sulfur to form inorganic arsenic compounds -arsenic in animals and plants, combine with carbon and hydrogen to form organic arsenic compounds -inorganic arsenic compounds have been identified as a group of carcinogenic agents to humans -organic arsenic compounds are less acutely toxic than inorganic arsenic compounds -2400 years ago in Greece and Rome, arsenic (As) was used as a therapeutic agent and also as a poison -historically the poison of choice for many murders, in reality and fiction. -in the seventeenth and nineteenth centuries, there were frequent attempts at poisoning, using arsenic compounds -arsenic's popularity declined dramatically in the latter half of the nineteenth century, due to the development of highly reliable and sensitive assay for arsenic

microbial toxins

-bacterial toxins (staphylococcal enterotoxins, botulinum toxins, other pre-formed bacterial toxins) -mycotoxins (mycotoxins from molds, toxic or poisonous mushrooms) -algal toxins

toxicity note

-based on several dose-response studies, researchers have established different toxicity levels or ratings for substances. the toxic doses of chemical substances vary and have a wide range of lethal doses have a wide range -these ratings hold good when we have data from the single chemical exposures

exposure to PAHs

-breathing air containing PAHs in the workplace of coking, coal-tar, and asphalt production plants; smokehouses; and municipal trash incineration facilities -breathing air containing PAHs from cigarette smoke, wood smoke, vehicle exhausts, asphalt roads, or agricultural burn smoke -coming in contact with air, water, or soil near hazardous waste sites -nursing infants of mothers living near hazardous waste sites may be exposed to PAHs through their mother's milk -we are most likely to be exposed to PAH vapors or PAHs that are attached to dust and other particles in the air -sources include cigarette smoke, vehicle, exhausts, asphalt roads, coal

toxicity

-capacity to cause adverse effects on whole/part of the living organism -the degree to which it is toxic

note

-certain chemicals in food eaten by a fish tend to accumulate in its liver and other tissues- the chemicals are taken in faster than the individual can get rid of them (PCBs are stored in fat, cadmium is stored in the kidneys)

toxicity and toxication depend on many factors:

-chemical structure of the toxicant -route of administration -duration of exposure -number of exposures -physical form of toxicant -genetic constitution and overall health of an individual

chemical contamination

-chemicals when used inappropriately or incorrectly, they can become food safety hazards -chemicals can become very harmful if they are: spilled on or near foods, mistaken for food or drink -certain chemical substances such as food additives and cleaning products are used in the production of food; to clean kitchen surfaces and equipment, as pesticides -may occur naturally or as added chemicals

importance

-contaminate 25% of the world's food crops -commodity loss- low market value and rejection affected commodities -lowered animal and human health impacts, human toxicity -economic impact of 1 billion metric tons of food and food product losses -$0.5 million to over $1.5 mycotoxin related losses in the United States annually -losses due to mycotoxins and costs of mycotoxin management are overlapping areas of concern -health wise, the mycotoxins pose a major risk to human and animal health

early onset

-coprine, GI toxin, muscarine, psilocybin, Ibotenic and muscimol

dietary supplements- regulated by FDA (CFSAN) via DSHEA

-dietary supplement health and education act of 1994, public law 103-417 an act (to amend the federal food, drug, and cosmetic act to establish standards with respect to dietary supplements, and for other purposes) -DSHEA Provisions: distinction of dietary supplement from drug, food & food additive (regulated by 1958 amendment to FD&CA; included GRAS definition) drugs- claim of therapeutic effect; tested for efficacy, example: drug lovastatin "lowers risk of heart disease" -health supplement cholestin (Chinese red rice) promotes healthy cholesterol **labeling requirements, includes prohibition of comparison to drug "herbal fen-phen" not allowed **defines adulteration to include lack of evidence of safety **post-marketing notification of safety issues

top five food sources of each toxin

-dioxins: dairy, meat, potatoes, cereal, mushrooms -acrylamide: crackers, fried potatoes, cereal, graham crackers, chips -also, foods with the highest pesticide residues were (non-organic): tomatoes, peaches, apples, peppers, grapes, lettuce, broccoli, strawberries, spinach, pears, green beans, and celery

aflatoxin outbreaks/recalls

-during 1967 in Taiwan: death of 3 children due to liver necrosis, consumption of contaminated rice (200 ppb) Ling et al. 1968 -first epidemic in during 1974 in India: 108 deaths due to consumption of maize contaminated with aflatoxin (15,000 ppb) Krishnamachari et al. 1975 -In Kenya *During 1980: 20% mortality reported Ngindu et al. 1982 *During 2004: 317 cases and 125 deaths, Lewis et al. 2005 *During 2005 in U.S.: more than 75 dogs died

three forms of mercury

-elemental -inorganic -organic

note

-endotoxins are part of the outer cell wall of bacteria. endotoxins are invariably associated with gram-negative bacteria as constituents of the outer membrane of the cell wall. although the term endotoxin is occasionally used to refer to any "cell-associated" bacteria toxin, it should be reserved for the lipopolysaccharide complex associated with the outer envelope of gram-negative bacteria such as E. coli, salmonella, shigella, pseudomonas, neisseria, haemophilus, and other leading pathogens

mushroom poisoning in US

-every year across the United States, more than 9000 cases of mushroom ingestion are reported to the American association of poison control centers -5 exposures per 100,000 population, most exposures are relatively benign -approx 5% result in moderate poisoning -approx 3 deaths per year -children under the age of 6 years account for a majority of these cases -in 85 to 90% cases, mushroom not identified

examples of toxicant types of classes

-exposure classes (air, water, food occupational) -usage classes (solvents, drugs, pesticides) -chemical categories (organic, inorganic, metals) -toxic responses or effects (neurotoxic, hepatotoxic)

mercury in foods

-fish is primary source of mercury and highest concentration of mercury can be found in people eating lot of seafood -methyl mercury is taken up through the intestinal wall -methyl mercury easily passes through the placenta and can affect the fetus- may cause neurological damage -major health concern is damage to the brain and nervous system, may also affect the immune system -highest concentration of mercury can be found in people eating a lot of seafood

exposure to arsenic

-food: arsenic in the air can be washed to the ground when it rains, contaminating crops and fields -water: water may have arsenic in it if there are high levels of arsenic in the rocks through which water flows -air: sawdust and smoke from burning arsenic-preserved wood may contaminate the air we breath

ciguatoxins

-foodborne diseases/syndromes (ciguatera) -associated foods/ occurrence (coral reef fish from extreme southeastern U.S., Hawaii, subtropical/tropical regions worldwide, recently reported in northern gulf Mexico) -these toxins become progressively concentrated as they move up the food chain from small fish to large fish that eat them, and reach particularly high concentrations in large predatory tropical reef fish

chemical contaminants in foods

-insecticides and pesticides -industrial and environmental contaminants -halogenated hydrocarbons (polychlorinated biphenyls, PCBs, dioxins) -heavy metals (mercury, arsenic, lead, cadmium, chromium, copper, nickel)

okadaic acid group (dinophysis toxins)

-foodborne diseases/syndromes (diarrhetic shellfish poisoning DSP) -DSP is a gastrointestinal illness without neurologic manifestations -the causative organisms are the marine dinoflagellates called dinophysis that produce toxin okadaic acid -it is caused by the consumption of contaminated shellfish or bivalves (clams, oysters, mussels, scallops, and numerous other families of shells) also called filter feeders -associated foods/occurrence (molluscan shellfish, reported in Japan, Southeast Asia, New Zealand, Western Europe and Scandinavia, and eastern Canada) -clinical presentation: this is a self-limited diarrheal disease -diarrhea is the most common symptom, followed by nausea and vomiting -onset time is 30 minutes to 12 hours from ingestion. complete clinical recovery is seen even int severe cases within 3 days -treatment is symptomatic and supportive with regards to short-term diarrhea and accompanying fluid and electrolyte losses. in general, hospitalization is not necessary; fluid and electrolytes can usually be replaced orally

excretion note

-for example, activity of many enzymes in very low in newborn babies and generally the younger ones are more sensitive to many chemicals than adults. sex differences, in comparison female rats, Male rats are most resistant to organophosphate insecticide parathion that could be because of the greater activity of the hepatic cytochrome P-450 monooxygenase system, which metabolizes parathion to non=toxic metabolites -once a substance is in the bloodstream, it may be further distributed between various tissues, excreted from the organism or stored, and biotransformed into different metabolites; the substance or its metabolites may interact or bind with cellular components of tissues where they were distributed

aflatoxins

-group of mycotoxins produced by certain fungi as secondary metabolites -unavoidable natural contaminants of food and feedstuffs -second metabolites are generally produced following active growth of fungi

scombrotoxic fish poisoning

-high levels of histamine in fish means that decomposition has occurred (even if the decomposition is not obvious) -toxic amounts of histamine can form before a fish smells or tastes bad -scombroid poisoning is an allergic-type reaction to high levels of histamine in fish -onset: immediate to 30 minutes -initial symptoms: tingling or burning sensation in the moth, rash of the upper body, drop in blood pressure, headache, itching of the skin -later symptoms: nausea, vomiting and diarrhea -duration: 3 hours to several days -treatment: antihistamines -control: proper chilling and temperature control -FDA guideline: 50 ppm -once histamine is formed it does not go away and no amount of washing or cooking will remove or destroy it -freezing will not reduce or destroy histamine after formed -prevention is the only way to assure that histamine is not in fish in first place

classification based on potency (high p)

-high potent: products produced in nature for the purpose of repelling or killing (low dose effects) -spider and snake venoms, chrysanthemum pyrethrins -botulinum toxin by clostridium botulinum

mycotoxins (mushrooms), toxic or poisonous

-human populations have learned to distinguish between "poisonous" and edible mushrooms, often by trial and error -despite centuries of accumulated knowledge, mushroom poisoning still occurs in modern times- occasionally reported as food borne illness outbreaks (cdc 2009) -5000 species of mushroom are known -approximately 100 species are confirmed poisonous -only 200-300 species are clearly established as safe

toxicity outcomes

-in experimental toxicology, the adverse effects are designated as toxic endpoints or health outcomes -it can be a physiological response, a biochemical change or a behavioral response, should be measurable -endpoints are used to measure/quantify toxicity - the poison or poisonous substance has connotations of causing death or being used in homicide or suicide cases

note

-in order to understand a dose-response mechanism, let look at dose response data. to do this, we can begin by plotting some data points that we generated in a hypothetical experiment involving a group of mice treated with anew drug. typically, the experimental data is plotted with the x-axis representing the different doses or exposure concentrations, often on a log scale -the concentrations go from low to high (left to right) the y-axis shows the response data for each experimentally-derived dose exposure. the units for y-axis in this graph is percent cumulative response over a given time period -hypothetical data about mice mortality responses for a drug dose. mortality data are often used to determine what is known as LD50 for a drug or compound. determining the LD50 of a drug, compound of toxicant is an important first step in discerning relative toxicity -mice exposed to each of six drug doses, hypothetical data, each data point represents percent mortality at each dose. in first, low dose we see 0% response-no mice succumbed sue to exposure, at higher and higher doses there was an increase in % response

note

-ingested and inhaled substances are considered outside the body until they cross the cellular barriers of the gastrointestinal tract (GIT), the respiratory system, or the skin -when a substance is in the GIT, in the lungs, or on the skin, it finds itself in the physiological route of absorption-distribution-metabolism-excretion (ADME). now its toxicity depends on many factors, including the speed and the exact way of moving along this system. in most cases, the toxic effect is proportional to the toxicant's concentration in the blood. the intensity of the toxic effect depends on the pharmacokinetics of the toxicant, that is, how the compound enters the organism and the bloodstream (absorption), how and in which (original or metabolic) form it moves along the body (distribution and metabolism), and how the xenobiotic and/or its metabolites leave the organism (excretion). the pharmacokinetics of a toxicant is substantially influenced by the age, gender, lifestyle, nutritional condition, and dietary habits of the individual, tissue (liver, kidneys) functions and conditions, and so forth -three of the blocks in the aforementioned scheme-absorption, distribution, and excretion-are connected with the reanspositiony of the substance in the organism, which comprises crossing of biomembranes

current use of arsenic

-use is dropping because of toxicity -90% used as wood preservative (phased out) -cotton field -silicon based computer chips -feed additive (poultry and swine)

entry of toxins

-into a living organism may occur by way of skin, lung, GI system and injections. if they are to show their toxic effects, they should pass into the circulation system through biological membrane and travel to their target points. therefore, the toxicity of the same substance can differ at different times or in different victims, according to its means of entrance to the organism

ciguatera fish poisoning

-is an illness caused by eating fish that contain toxins produced by a marine micro algae called gambierdiscus toxicus -ciguatoxins that cause ciguatera poisoning are actually produced by microscopic sea plants called dinoflagellates

acute toxicity

-is mainly sue to exposure to single or multiple toxic doses over 24 hours or less time. toxicity may develop quickly with severe symptoms. exposure to high levels of (50-60 mg) of potassium cyanide can lead to death in few minutes. acute toxicity is typically measured in animals (rats and mice) and defined in terms of the lethal dose 50 (ld50) or lethal concentration (LC50) -sometimes acute effects can be seen after a long time interval (hair loss and carcinogenic effects after exposure to radiation) this is called delayed acute effect

toxicology

-it is a science that studies the formation, composition, and properties of toxicants, their mode of action on organisms, reduction of their adverse effects, assessment of toxicity, medication of the toxicity and other aspects -toxicology also deals with the substances that are essential for the body, such as harmones, amino acids, vitamins and exogenous substances such as food additives, that might have toxic effects at high levels

Therapeutic index

-knowledge of effective and toxic dose levels aides the toxicologist and clinician in determining the relative safety of pharmaceuticals. this is done by determining an effective dose instead of a toxic dose using therapeutic index calculation. for therapeutic outcomes, calculation of therapeutic dose is considered and an effective dose is determined using TI calculation. effective doses (ED) are used to indicate the effectiveness of a substance. normally, effective dose refers to beneficial effect (relief or pain). similarly toxic doses (TD) indicate adverse toxic effects -this graph explains how we can do that. consider the situation where we have information or data about increasing response of an organism to an increasing exposure. let us look at the effective responses of an organism under treatment. as shown in figure, two dose response curves are presented for the same drug, one for effectiveness and other for toxicity. a dose effective for 10% of the population, the is called ED10, ED50 if it is effective - a dose that is 50-75% effective does not cause toxicity whereas a 90% effective dose may result in a small amount of toxicity. we use TI to compare the effective and toxic doses. it is the ratio of the dose of the drug that produces an unwanted (toxic) effect to that producing a wanted (therapeutic)

margin of safety

-let us consider the similar situation wherein we compare two different drugs being used for recording the recovery of test subjects. the two drugs may show similar effective-dose response curves and they may show different toxicity response curves as show above. here if we were to use TI as our estimate and consider the 50% response values, we will use the substance B which is more toxic than the substance A. in such a case, we have consider the results of maximum effective dose and least toxic doses. in this example, substance A and B have the same LD50 and ED50. use of ratios between these two values would give a TI of 10. but here we did not consider the differences in slope of the two curves. in such a case, we should consider the ratio of lowest toxic dose to the highest effective dose. as shown here. the TD of 1% toxic dose level and ED of 99% effective dose level should considered. by calculation, we can say that the substance B is less safer than A

endotoxins

-lipid portions of lipopolysaccharides LPSs that are part of the outer membrane of the cell wall of gram-negative bacteria (lipid A) the endotoxins are liberated when the bacteria die and the cell wall breaks apart

neurological effects

-long tern exposure can result in reduced IQ and learning disability, associated with permanent brain damage -a study in Mexico shows that children living in area with high levels of pesticide exposure had less stamina, poorer eye-hand coordination, poorer memory and were less skilled in drawing figures (Guillette, 1998) -the risk of developing Parkinson's disease is 70% greater in those exposed to even low levels of pesticides (ascherio et al, 2006) -there are also concerns that long term exposures may increase the risk of dementia (Baldi I et al, 2010)

classification based on potency (low p)

-low potency: products with high dose effects -pharmaceuticals -herbal food supplements (toxic episodes reported for excessive exposure)

the damage to birds can be grouped into four stages

-lowered feed intake and low productivity due to decreased liver functioning (decreased performance slow growth) -suppression of immunity (high susceptibility to diseases through secondary infections) -metabolic disorders and clinical signs of damaged organs -death

algal (marine) toxins

-marine toxins are naturally occurring chemicals that can contaminate certain seafood -the seafood contaminated with these chemicals frequently looks, smells, and tastes normal -when humans eat such seafood, disease can result -food poisoning through marine toxins is rare (about 30 reported cases/year) -marine toxin poisoning occurs most often in the summer -seafood poisoning occurs when marine toxins contaminate the seafood -the toxins produced by dinoflagellates and other toxigenic algae commonly in the sea environment -symptoms: dehydration caused by diarrhea and vomiting is most common complication -no specific treatments for marine toxin poisoning, treatment generally consists of managing complications and being supportive until the illness passes

arsenic in foods

-may be present in many foods including grains, fruits, and vegetables where it is present due to absorption through the soil and water -in addition, some seafood has high levels of less toxic organic arsenic -environmental protection agency assumes there is actually no "safe" level of exposure to inorganic arsenic -no federal limi exists for arsenic in most foods -as per EPA, the dietary exposure to inorganic arsenic is at 24% from vegetables, 18% from fruits and fruit juices and at 17% from rice

methods of analysis of aflatoxins

-physicochemical detection methods (TLC, HPLC and GC, HPLC/MS, GC/MS, HPLC/MS-MS) -immuno assays (bioassay by biosensor, ELISA, radioimmuno assay (RIA), immunoaffinity column assay (ICA)

note

-modern toxicology thus can be divided into various applied areas as; clinical, forensic, analytical, environmental, occupational, and regulatory -clinical toxicology as you may know deals with diagnosis and treatment of human poisoning, and forensic toxicology, the medical-legal aspects of clinical poisoning. the related discipline of analytical toxicology is concerned with the identification and quantification of toxic chemicals in biological materials -environmental and occupational toxicology are self-explanatory in that they deal with toxic hazards in the environment and in the workplace, respectively. -regulatory toxicology focuses on laws and regulations and their enforcement, an important component of toxicology

chemical contaminants in foods

-more than 10,000 chemicals are allowed to be added, directly or indirectly, to human food (as per US food and drug administration FDA) -as of 2010, over 90% of these additives were allowed in human food under the legal categories known as food additives or as generally recognized as safe (GRAS) substances in roughly equal numbers

mycotoxins

-mycotoxins produced by molds (filamentous fungi) though term also used for toxins produced by yeasts and mushrooms -between 300 and 400 compounds are identified as mycotoxins -only about a dozen groups of them receive regular attention for their toxicity to humans and animals -diverse in chemical structure and may originate from a variety of fungal species and biosynthetic pathways

sources of mercury

-natural: volcanic activity, forest fires, erosion -anthropogenic: metal production, pulp industries, waste handling and treatment, coal, peat, and wood burning, 50-75% mercury in the environment -based on lake sediment records, it is estimated that the atmospheric inputs of mercury have tripled over the past 150 years. this indicates that two thirds of the mercury now in the atmosphere, and hence in surface seawater, is of anthropogenic origin, and one third is from natural sources

note

-nearly all toxicants are capable of causing multiple adverse effects and these effects depend on many factors as listed -exposure of contact must first occur for the chemical to present a risk (risk is probability of harm or adverse effect) exposure decided the dose -the magnitude of risk is proportion to both the potency of the chemical and extent of exposure

brevetoxin group

-neurotoxic shellfish poisoning (NSP) -molluscan shellfish harvested from coastal gulf of Mexico and southern Atlantic. similar toxins in New Zealand and suggested occurrences elsewhere -toxin produced dinoflagellates usually found in oysters, clams, and mussels from the gulf of Mexico and the Atlantic coast of the southern United States -cause symptoms in 1 to 3 hours. they include numbness, loss of coordination, an upset stomach, and tingling in the mouth, arms, and legs. they usually last 2 to 3 days -death is rare. recovery normally occurs in 2 to 3 days

what causes algal blooms

-nitrogen/ phosphorous leading to eutrophication -vitamins B12, thiamin, biotin -temperature (optimal at 25 C, usually in summer) -light -pH -oxygen -pristine waters

potential sources of toxicants in foods

-nutrients -chemicals or substances intentionally added to food (food additives) -natural food toxicants -other contaminants

partial or complete degradation or removal of nutritives that may reduce food utilizability and digestibility

-nutrients or food components subjected to changes during processing are; amino acids, proteins, sugars, carbohydrates, vitamins and lipids

note

-once absorbed into the blood plasma, a chemical substance is distributed throughout the body -generally, toxic substances are bound to proteins and other biomolecules as follows

food processing changes

-overall the aims of food processing are mainly to increase safety, quality and palatability of foods -during processing of food and food ingredients, several chemical and physical processes occur

dinoflagellate

-paralytic shellfish poisoning (PSP) -diarrheal shellfish poisoning (DSP) -neurotoxic shellfish poisoning (NSP) -ciguatera fish food poisoning (CFP) -estuary-associated syndrome (EAS)

saxitoxin group

-paralytic shellfish poisoning (PSP) -molluscan shellfish harvested from US northwest and northeast coasts -reports from temperate to tropical regions elsewhere in the world. toxins found in the viscera of mackerel and several species of crustaceans (lobster and crabs) in the U.S. -the dinoflagellates producing PSP are usually associated with red-brown color and in large numbers can cause a red streak called "red tide" in the ocean -usually causes symptoms within 2 hours of eating the shellfish, although symptoms may occur within 15 minutes or after as long as 10 hours -symptoms usually begin with numbness or tingling in the face, arms, and legs, followed by headache, dizziness, nausea, and loss of coordination -symptoms are usually mild, although severe symptoms have occurred -cooking may not destroy the toxins, so buy your fish from a good source

notes

-people who have ciguatera may experience nausea, vomiting, and neurologic symptoms such as tingling fingers or toes. the sensation of burning or pins and needles, weakness, itching, and dizziness can occur -patients may experience reversal of temperature sensation in their mouth (hot surfaces feeling cold and cold, hot), unusual taste sensations, nightmares, or hallucinations. ciguatera poisoning is rarely fatal -ciguatoxin usually causes symptoms within a few minutes to 30 hours after eating contaminated fish, and occasionally it may take up to 6 hours. symptoms usually clear in 1 to 4 weeks -ciguatera has no cure. symptoms usually go away in days or weeks but can last for years. people who have ciguatera can be treated for their symptoms -cooking does not destroy the toxins, so buy your fish from a good source -four categories: diarrheal, paralytic, neurologic, and amnestic shellfish poisonings -toxins are found in microscopic diatoms and dinoflagellates with concentrations occurring in filter feeding bivalves, such as clams or mollusks

insecticides/pesticides

-pesticides are the chemicals or mixtures of chemicals used fro prevention, elimination or control of unwanted insects, plants and animals -pesticides are often referred to according to the: type of pest they control, derived from a common source or production method (chemical pesticides, biopesticides, antimicrobials, pest control devices)

biotransformation sites

-phase 1 reactions involve oxidation, reduction and hydrolysis -phase 2 reactions consist of conjugation or synthesis -excretion, metabolism

poisonous mushrooms

-poisonous mushrooms contain compounds that are toxic to humans and animals -mode of action well known yet generally there are few antidotes available -7 major toxin groups are recognized as poisonous and an 8th toxin group of mainly gastrointestinal irritants

plant, algal and animal origin

-poisons: non-proteinaceous, smaller molecules, example: histamine- scombroid poisoning, bacterial conversion of histidine of host (canned fish, Swiss cheese) -toxins: high molecular weight, antigenic- vaccines (exotoxins- proteins, some heat labile destroyed by cooking, nomenclature from bacterial source- cholera & botulinum toxins), (endotoxin- lipopolysaccharide LPS, not heat-labile of gram negative enterobacteria)

food contaminants or food safety hazards

-poor food safety practices -food contamination (harmful things or hazards are present in food, making it unsafe to eat) -a hazard is something with the potential to cause harm -food safety hazards: natural and man made (physical, chemical and biological)

features useful for identifying poisonous mushrooms

-presence of annulus (ring) on stalk -presence of a volva (cup) at base of stalk -scales on cap -spore color -staining reactions of spores and cap

types of harmful algal blooms (HABs)

-produce dense blooms leading to oxygen stress (dinoflagellates, diatoms, raphidophytes, prymnesiophytes, cyanobacteria (prokaryotic microbes) -produce potent toxins- illness and death via food chain or biomass accumulation -cyanobacterial toxin poisoning (CTP)

acrylamide in foods

-produced industrially for use in products such as plastics, grouts, water treatment products, and cosmetics. also found in cigarette smoke -can form in some foods during high-temperature cooking processes, such as frying, roasting, and baking -boiling and steaming do not typically form acrylamide. acrylamide found mainly in foods made from plants, such as potato products, grain products, or coffee -acrylamide in food forms from sugars and an amino acid that are naturally present in food; it does not come from food packaging on the environment -generally, acrylamide is more likely to accumulate when cooking is done for longer periods or at higher temperatures

free form toxic substances

-protein bound toxic substances (move in the circulatory system until it is bound to another biomolecule or to a tissue component) -cellular binding results from the affinity of a substance to some cellular components

exotoxins

-proteins produced inside pathogenic bacteria, most commonly gram-positive bacteria, as part of their growth and metabolism. the exotoxins are then secreted or released into the surrounding medium following cell lysis

analysis of aflatoxins

-sampling: major source of error or variability, to obtain representative test portion (10 pound sample- ground and mixed- 500 gm. sub sample- 50 gm. test portion) -extraction: liquid-liquid extraction LLE, solid-phase extraction SPE -purification (if necessary) and determination

natural toxins regulatory & control measures

-seafood: regulated by FDA, NOAA & states (inspection by source- Plankton counts in shellfish beds, inspection of product & its production- certification & licensing, product testing) -meat & poultry: regulated by USDA (FSIS) (procedure similar to seafood except sources (farms, herds) not inspected) -hazard analysis critical control point (HACCP)- procedures implemented beginning in 1997 to shift control from older policy of "post-marketing" to "pre-marketing" surveillance. introduction of newer testing methods

absorption

-since a drug or chemical has to be absorbed first by an organism to cause any effect, absorption is a primary focus for drug design, development, and treatment -the entrance of the toxin into the blood circulation system by passing through the biological membranes (the transfer of the substance from site of entry to the circulation system and not to the site of action) -cell membranes of various cells of the organism such as skin keratinocytes, intestinal enterocytes, vascular endothelial cells, liver hepatocytes, and the nuclear membrane- are not same. however the basic compositions of the membranes are very similar -toxins are absorbed in different tissues according to their means of entrance, the toxic effect the toxins begins at the point of entry, such as skin, oral region or inhalation membranes

therapeutic index (TI)

-statement of relative safety of a drug -ratio of dose producing toxicity to the dose needed to produce the desired therapeutic response

note

-streptomycin is produced from streptomyces griseus. used for treating TB and bacterial infections. works by stopping protein synthesis -acetylsalicylic acid or aspirin belongs to NSAIDs group. works by inhibiting synthesis or chemicals of blood blotting and also that sensitize nerve endings and cause pain (it comes from the A in acetyl chloride, the sir in spiraea ulmaria the plant from where salicylic acid was derived and in was then a familiar name for medicines -cyclosporine is given to prevent transplant rejections in patients who have received organ transplants, also used for cats and dogs. it works by suppressing the action of certain cells in the immune system -herbal or dietary supplements, aloe vera for skin treatment-eczema psoriasis

pharmaceuticals (tested fro safety and efficacy)

-streptomycin: amino glycoside antibiotic from soil bacteria (toxicity- kidney) -acetylsalicylic acid: non-steroidal anti-inflammatory analgesic from willow bark (toxicity- gastric, renal) -cyclosporine: immunosuppressant from fungus (toxicity- kidney)

subacute vs subchronic

-subacute: usually repeated exposure during 1 month -subchronic: continuous contact during 1-3 months

arsenic in rice

-the average total and inorganic arsenic levels are usually higher in the brown rice than in the white rice -arsenic concentrates in the outer layers of rice grain. in case of white rice, the process of polishing the rice to produce white rice removes those surface layers, slightly reducing the total arsenic and inorganic arsenic in the grain -in brown rice, only the hull is removed. arsenic concentrations found in the bran that is removed during the milling process to produce white rice can be 10 to 20 times higher than levels found in bulk rice grain

note

-the biotransformation occur at both the biotransformation sites and toxic sites -the rate of metabolism of toxic compounds to less-toxic products, or less-toxic compounds to more-toxic products is of primary importance concerning the overall toxicity observed after the exposure of animals to these compounds -the metabolism rates of these compounds are affected by several factors that can be summarized as age, difference in sex, strain and species, nutritional status, enzyme induction, pathological situations

note

-the effects of aflatoxins on health and productivity of poultry varies with concentration of intake, length of exposure, species, breed, diet and nutritional status. furthermore, research showed that young chicks are more sensitive than adults

acute vs. chronic exposures and effects

-the exposure to toxicants in foods varies from acute to chronic. similarly the adverse effects from toxicant exposures can range from acute to chronic

toxication

-the harmful effect (outcome) as a result of entry of toxicant into a living organism

mushroom poisoning (early onset, late onset)

-the onset effects associated with mushroom toxins maybe early onset (occurs shortly after consumption) or late onset (symptoms are delayed for days or weeks)

note

-the processes of movement of substances across biological membranes are classified as passive and active transport -passive diffusion processes do not require energy in the form of ATP and are driven by concentration gradients. most of the toxicant's are absorbed by passive diffusion -passive diffusion include simple diffusion and facilitated diffusion

what determines toxicity

-the relationship between toxicant and effect on the organism -this is called "the dose response" mechanism -dose: amount of exposure to an agent (Mg/kg, mg/cm, ppm, mg/m) -response: maximum reaction to the dose (effect-%) -the single most important factor determining the potential harmfulness or safeness of a compound is the dose-response relation between the compound and the organism -unit: mg/kg (per unit weight), mg/cm (per area of skin surface), ppm (per unit volume of air inhaled (gas/vapor), mg/m (for solids inhaled in air)

note-absorption

-the role of the interstitial fluids and lymph in the transport of substances is generally less important. for crossing of membranes, a substance always selects the easiest way -toxicants cross the membranes through the same passages as the endogenous compounds

note

-the toxicities of aflatoxin B has been well established in several animal species -rainbow trout develop hepatomas (liver cancer) with about 97% incidence when fed as little as 90 parts per billion of aflatoxin in their feed. this makes a very good model for cancer research. it has constant predictable mortality or morbidity rate -the first documented incidences of aflatoxicosis affecting fish health occurred in the 1960s in trout hatcheries. domesticated rainbow trout (oncorhynchus my kiss) that were fed a pelleted feed prepared with cottonseed meal contaminated with aflatoxins, developed liver tumors (Ashley, 1970). as many as 85% of fish died in these hatcheries (taniwaki, 2001). -although the animal species may show variation in their susceptibility to aflatoxins, the severity os aflatoxin toxicity depend on many factors such as dose, age, sex, mode of application, duration of feeding and other factors such as stressors affecting an animal. in general, several research reports agree that aflatoxins are more toxic for young animals (IARC, 1993, Vainio et al., 1994)

heavy metals in foods

-these are the minerals that are naturally present in rocks and soils in all parts of the world (mercury, cadmium, lead) -mercury Hg is a natural element that occurs in terrestrial and aquatic ecosystems in the arctic -it is shiny, silver-white, odorless metal and it is the only metal to exist as liquid at room temperature -cadmium and mercury are released as a by-product of mining and smelting- primary long range transport is through the atmosphere -significant quantities of mercury are also released as a result of the erosive and chemical actions that take place in reservoirs built to store water for large hydro-electric projects -metal levels are highest in people who eat large amounts of organ meat

roles of GRAS substances in foods

-they perform many roles, including preserving flavor, enhancing taste or appearance, preventing spoilage, and as constituents of packaging -about 10% of these chemicals are in similar categories such as color additives, pesticides, etc

typical dose-response curve

-this promise states that toxicity of a substance increases with increasing dose -in quantitative terms the dose is the amount of substance administered over a specified period of time. virtually any substance can be toxic with too much dose. many substances confer protection or health benefits at lower doses but become toxic with increasing doses

note

-toxicology is multidisciplinary science and closely related to other sciences such as pharmacology, immunology, biology, pathology, physiology, chemistry, biochemistry, food and public health and so on. for example, biochemists who have expertise in biology and chemistry of biomolecules can study the fates of agents In living organisms and the mechanisms or disease mechanism, geneticists, who investigate the effects of agents on genetic material and the impact of genetic variation on responses to toxic insults -pharmacologists deal with the therapeutic properties and desirable changes in organisms, whereas toxicologists deals with undesirable changes, there are many other disciplines that provide information of importance (epidemiologists, who study populations exposed to such agents to look for possible connections between exposures and adverse health outcomes) -the information or knowledge about a particular substance can fall into any of these forms as it can be the analytical information or clinical, environmental, forensic, occupational, and regulatory information. these inputs are reflected in the names of the different branches of toxicology

notes

-toxicology is the study of the adverse effects of chemicals on living organisms. we study various aspects of toxicity. it can be defined as the "science of poisons" -although toxicology deals with toxicants, we also study adverse effects of certain essential substances for the body such as harmones, amino acids, vitamins, and other substances such as food additives that may cause toxicity if consumed in excess. such substances may sometimes be found in foods and we study about them in a major branch of toxicology called food toxicology

storage sites

-toxins accumulate in different cells, tissues or organs of the body -organs, lipid tissues, bones, other tissues

excretion (kidney, lungs, saliva, sweat, tears, milk, bile, feces)

-various routes from the body excrete the toxins that are absorbed and distributed in the living organism -the kidney is very important organ for excretion of toxins and probably more chemicals are eliminated from the body by this route than any other -many toxic material change into their polar metabolites and are eliminated in these forms -lungs eliminate toxins in gas and vapor phases. saliva, sweat, tears, milk, bile, and feces are also secondary routes for excretion of toxins

does washing fresh produce eliminate pesticide residues from food

-wash produce with large amounts of cold or warm tap water, and scrub with a brush when appropriate; do not use soap -throw away the outer leaves of leafy vegetables such as lettuce and cabbage -in case of meat, trim the fat from meat, and fat and skin from poultry and fish. residues of some pesticides concentrate in animal fat

what is a chemical residue

-when a food product or crop is treated with a chemical or pesticide, a very small amount of the chemical or its metabolites or degradation products can remain in the crop or in the final food product. this is known as the residue -chemical residue may be present in fresh or tinned fruit and vegetables or processed food and beverages or fresh or processed animal products

translocation

-when a substances is absorbed, it passes through the cell linings of the absorbing organ into the interstitial fluid surrounding the cells and further to blood capillaries and general circulatory system -translocation (change in location) means the transfer of a toxic substance along with the blood to a storage site -once absorbed into the blood plasma, a chemical substance is distributed throughout the body -translocation means change in location. the term is commonly used in genetics. here translocation means the transfer of a toxic substance along with the blood to storage sites. the movement usually occurs from areas with high degree of blood flow, to the high permeable region of a tissue and to reaching a binding place to accumulate. usually the region with less blood flow is suitable for accumulation

note

-when we note measurement and fit a line to these data points we see that there is a sigmoid shape to that data, this is typical for dose response graphs, curve is best fit line, it does not necessarily go through each and every data point -most commonly, when studying dose-mechanism we may see that there could be toxic and nontoxic doses for any substance. in addition, we may also inquire about the effect of intermediate doses. dose response curve takes a sigmoid shape because some small doses are showing a no toxic effect. no observable effect level (noel) meaning there may or may not be a effect on the organisms but we can't see it in this experiment -the point at which toxicity first appears is known as the threshold dose level. a threshold for toxic effects occurs at the point where the body's ability to detoxify a xenobiotic or repair toxic injury has been exceeded. for most organs there is a reserve capacity so that loss of some organ function does not cause decreased performance -from that point, the curve increases with higher does levels. in the hypothetical curve shown above, no toxicity occurs at 50 mg whereas at about 110 mg, nearly 50% of the individuals experience toxic effects. this is called LD50 (median lethal dose) -studying the dose response models helps in determining the safe and hazardous levels of a substance

arsenic in rice

-while most crops don't readily take up much arsenic from the ground, rice is different because it takes up arsenic from soil and water more readily than other grains -rice is grown in water-flooded conditions, which allow arsenic to be more easily taken up by its roots and stored in the grains -elevated levels of arsenic in rice from LA, MS, MO and TX may have originated from the long history of cotton cultivation in that region, an industry that extensively utilized lead-arsenate insecticides

major groups of toxins produced by dinoflagellates

1. ciguatoxin- tropical fish poisoning 2. okadaic acid- DSP 3. saxitoxin- PSP 4. brevetoxin- NSP 5. domoic acid- ASP -other major marine toxin: scombroid or scombrotoxin or histamine causes 'scombrotoxic fish poisoning'

who monitors pesticides

EPA, FDA, USDA

note

GRAS substances range from common food ingredients (such as wheat) to newly engineered substances using biotechnology

toxikos

a bow

toxicant (poison)

a chemical (synthetic) substances causing adverse health effects (poison->exceptionally toxic)

fertility

a number of pesticides including dibromochlorophane and 2,4-D has been associated with impaired fertility in males (Sheiner EK et al, 2003)

toxicon

a poisonous substance into which arrowheads were dipped

venom

a toxin normally secreted by bugs/snakes, etc

in other tissues

accumulation in different tissues may depend on the chemical properties of the substances. for example, arsenic accumulates in keratin-rich tissues, whole iodine collects in the thyroid glands and carbon monoxide accumulates in the hemoglobin of the blood -this accumulation may occur as a result of the binding of the toxic material specifically in a definite region or by being soluble in lipids

carbamate pesticides

affect the nervous system by disrupting an enzyme that regulates acetylcholine, a neurotransmitter. the enzyme effects are usually reversible. there are several subgroups within the carbamates (bendiocarb, carbaryl, methyl, and propoxur)

late onset

orellanine, gyromitrin, cyclopeptides

toxicological knowledge

analytical, clinical, environmental, forensic, occupational, regulatory

toxin

any poisonous (=protein) substance produced by a living organism

cancer

associations have been found with: leukemia, lymphoma, brain, kidney, breast, prostate, pancreas, liver, lung, and skin cancers

general classification of natural toxins

based on: -potency -source and mode of action

classification of toxicants

based on: 1. chemical structure 2. physical state 3. usage/application 4. labels 5. toxic effect 6. method of isolation 7. others

biological factors influencing toxicity

besides the toxicant's chemical structure and the dose, other factors also influence determination of the target organ and the types and degree of adverse effects -exposure -absorption -distribution or transformation -metabolism or transformation -elimination or excretion

toxicology

biology, chemistry, pathology, genetics, pharmacology

pyrethroid pesticides

developed as a synthetic version of the naturally occurring pesticide pyrethrin, which is found in chrysanthemums. they have been modified to increase their stability in the environment. some synthetic pyrethroids are toxic to the nervous system (permethrin, resmethrin, and sumithrin)

forensic tox.

diagnosis, therapy, medico-legal aspects

economic tox.

drug development, food/food additives, pesticides/insecticides, herbicides, product safety

bacterial toxins

exotoxin, endotoxin

biologic factors influencing toxicity

exposure to chemicals -mode of entry- cellular barriers -cellular barriers that a toxicant must cross to cause an effect are (gastrointestinal tract GIT, respiratory system or lungs, skin- intravenously and intramuscularly) -toxicity may differ with mode of entry of toxin/s or its metabolites into an organism -is exposure alone is sufficient to cause toxicity -from the standpoint of food toxicity we are dealing primarily ingestion as a mode of entry

how the chemical contamination of foods occurs

food contamination with chemicals may occur through -environmental pollution of the air, water and soil, such as the case with toxic metals, PCBs and dioxins, through industrial pollution, by accident, ignorance or recklessness -through the intentional use of various chemicals, such as pesticides, animal drugs and other agrochemicals as residues -or through natural presence in foods (heavy metals)

food processing

food processing is the conversion of raw material or ingredients into a consumable food product

how PAHs are formed in food

high temperature cooking methods such as pan frying or grilling directly over an open flame can create harmful heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) -cooking meat or other foods at high temperatures that results in charring of the food increases the amount of PAHs in the food -these chemicals are formed in muscle meat such as beef, pork, fish, and poultry, if it is cooked using a dry, high temperature method -HCAs and PAHs cause cancer in animals, and some research has shown the same may be true in humans. you can reduce the formation of these harmful compounds by avoiding direct exposure of meat to an open flame or a hot metal surface; by reducing the cooking time, cooking in water, or by marinating meat before cooking it -cooking meat in water is a very gentle process that does not create a crispy brown or charred surface, which is where these harmful chemicals are found. soups, stews, casseroles or curries are all healthy ways to consume meat and poultry -marinating in an acid like lemon or lime juice or vinegar also reduces the formation of these compounds

occupational health tox.

industrial hygiene, regulatory

in lipid tissues

lipid soluble substances such as PCBs accumulate in lipid tissues and show their toxic effects in the blood. these substances can also accumulate in fatty tissues

in the bones

many toxic chemicals, such as fluorides, lead, accumulate in bones. they may accumulate by replacing calcium ions in bones

note

mercury distribution and exposure is a global problem

logos

of knowledge, study of

mercury in foods

organic mercury in foods is methyl mercury (MeHg) -MeHg is the most toxic form of mercury -major source of mercury is through meat, in the form of methyl mercury. other foods include potatoes. peas, beans and grains -it is methylates by sulfate-reducing bacteria to form MeHg (biomethylation) -limited amount is produced from anthropogenic sources -metallic mercury deposited in a lake or river settles into the sediment where bacteria may carry out oxidation and alkylation producing both water-soluble and lipid-soluble substances

disciplines of toxicology

pathology, pharmacology, physiology, public health, occupational health, forensic, economic, environmental, immunology, biology, chemistry

note

pollutants move from soil and water into plants, and from there into animals

environmental toxicology

pollution, residues, regulatory

formation of new potentially toxic substances such as;

polycyclic aromatic hydrocarbons (PAHs), amino acid or protein pyrolysates, N-nitrosamines

food toxicology

refers to mechanisms certain food additives that cause harmful health effects when consumed in high amounts, how they are formed during food processing, storage, cooking and how to avoid or reduce the, methods of assessments of toxicity and risk of food components

food and drug administration (FDA)

responsible for enforcing tolerances on all foods except meat, poultry and some egg products, establishes the laws pertaining to crops and agriculture processes. sets action levels with EPA

US department of agriculture (USDA)

responsible for evaluating and establishing the regulations pertaining to the pesticides though analytical studies

environmental protection agency (EPA)

reviews the scientific data on all pesticide products before they can be registered (or licensed) for use. if a product is intended for use on food crops, EPA also establishes a tolerance

health effects of 'As' exposure

short term exposure (high concentration in short amount of time) -vomiting -throat and stomach pain -bloody diarrhea long term exposure (low concentration over long period of time) -circulatory problems (trouble with blood vessels and circulation) -high blood pressure -cancer

nutritional toxicology

targets the interrelations that toxicants or toxins have with nutrients in the diet

note

the entrance of the toxin into the blood circulation system happens after the substance gains access to specific effector site within an organelle of an organism and passes through a series of membranes

in the organs

the liver and kidneys bind toxins more easily than other organs mainly via the proteins found in these organs

bioaccumulation

the process by which a contaminant accumulates in the tissue of an individual organism -biomagnification- increase in concentration of certain stable chemicals (for example, heavy metals or fat-soluble pesticides) in successively higher trophic levels of a food chain or web. E.g. metals such as mercury, persistent organic pollutants (POPs) such as PCBs, pesticides, dioxins (note: not all contaminants biomagnify) -the carnivore diet of humans in the arctic involves the consumption of species high up in the food chain- this results in a higher chance on poisoning. feeding on caribou vs. marine mammals exposes humans to different levels of contaminants

toxicology

the study of harmful interactions between chemicals and/or physical agents with biological systems

organophosphate pesticide

these pesticide affect the nervous system by disrupting the enzyme that regulates acetylcholine, a neurotransmitter. most organophosphates are insecticides. however, they usually are not persistent in the environment (parathion, malathion, and methyl parathion)

natural food toxicants

toxin- natural poison, not man made -toxicant- man-made synthetic (anthropogenic) chemical -these toxins are naturally produced from plants, animals and microorganisms -usually natural toxins are not acutely toxic, except in a few cases in animals -most of the natural toxins particularly those occurring in plant derived foods, induce adverse effects only after chronic ingestion or by allergic reactions

organochlorine insecticides

were commonly used in the past, but many have been removed from the market due to their health and environmental effects and their persistence (DDT and chlordane)