Toxicology - deck III

Question 1

Biodegradation of organic
environmental toxicants
occurs due to

Answer 1

direct contact with the microbial enzymes.

One enzyme molecule catalyzes decomposition of millions of organic molecules per minute.

Question 2

Biodegradation of organic environmental toxicants is usually a multi-step process, occurring

Answer 2

in the cooperation of a number of
microorganisms that often act synergistically.

Question 3

PAH

Answer 3

polyaromatic hydrocarbons or polycyclic aromatic hydrocarbons (PAHs) are a class of chemicals that occur naturally in coal, crude oil, and gasoline.

They result from burning coal, oil, gas, wood, garbage, and tobacco. PAHs can bind to or form small particles in the air.

Question 4

Classification of bioremediation methods (5)

Answer 4

1. Intrinsic bioremediation
2. Biostimulation
3. Bioaugmentation
4. Phytoremediation
5. Rhizoremediation

Question 4

1. Intrinsic bioremediation means

Answer 4

or natural attenuation,
happens naturally in the contaminated area, such as a petrol-polluted old gas station.

It relies on natural conditions and behavior of soil microorganisms that are indigenous
to soil.

Any site is unique, know-how obtained in one site is not directly conveyable to another contaminated site.

Question 5

2. Biostimulation remediation
   means

Answer 5

adding nutrients and other substances to soil to catalyze natural attenuation.

Nutrients in a gas or liquid form are added to soil or water where there is a need to
remove contaminants.

Bacteria are already there, they are just stimulated for growth
and activity. Essentially, the bacteria turn the harmful substances (and other) into CO2.

Question 6

3. Bioaugmentation remediation
   involves

Answer 6

introduction of exogenic microorganisms (sourced from outside the soil environment) capable of detoxifying and removing a particular contaminant, sometimes GMO are used.

Question 7

4. Phytoremediation is

Answer 7

Use of plants to clean up soil, water or air.

NB! These plants cannot be used for feed or food.

Question 8

5. Rhizoremediation is

Answer 8

the most evolved process of bioremediation,
involves removal of contaminants by mutual interaction of plant
roots and suitable microflora in the rhizosphere, the region of soil directly influenced by root secretions and associated soil
microbes.

• Pollutants remediated by this method are mainly organic compounds, unable enter the plant due to
  their high hydrophobicity.

NB! Plants will not become toxic.

Question 9

photolysis

Answer 9

also known as Photodegradation

Photolysis, as a chemical reaction that occurs under the influence of photons or light, may take place in the atmosphere and on the surface of either water or soil,but it does not occur in benthic sediments and deep
layers of soil.

Question 10

There are two types of photochemical reactions:

Answer 10

• direct photolysis
• indirect photolysis

Question 11

Ecotoxicology is a

Answer 11

subdiscipline of environmental toxicology studying
harmful effects of toxicants at the population and ecosystem levels.

Effects upon individuals are important if they are translated into effects at these levels.

Question 12

Biomagnification
is a process which results in

Answer 12

higher concentration of a substance in an organism than in its food.

The higher concentration of a
substance in an organism than in its food.

Question 13

Concentration of some chemicals in the fatty tissues of top
predators
can be ? of times higher than the concentration in the open water.

Answer 13

Concentration of some chemicals in the fatty tissues of top
predators
can be millions of times higher than the concentration in the open water.

Question 14

The real reason for biomagnification is

Answer 14

the time factor. Organisms, dwelling at higher levels of the food chain live longer and, hence, have more time for the bioaccumulation
of toxicants.

Question 15

QSAR

Answer 15

Quantitative structure-activity relationship (QSAR) analysis is a practical approach by which chemical structure is quantitatively correlated with biological activity or chemical reactivity.

QSAR is involved in drug discovery and designing to identify chemical structures with good inhibitory effects on specific targets and with low toxicity levels.

The most important purpose of QSAR modeling is to predict the activity/property/toxicity of new chemical entity (NCE) falling within the domain of applicability of the developed models.

QSAR models remain a good alternative to animal testing, which would otherwise be necessary to determine the toxicity of unknown substances.

Question 16

Two basic truths in the design of the animal studies are:

Answer 16

1. The adverse effect of a toxicant can, in “principle“, be extrapolated from animals to humans. (For human safety reasons, it is considered that humans are at least 10 times more
   sensitive than animals.)
2. To minimize the number of necessary laboratory animals.

Question 17

Genotoxicity tests

Answer 17

Genotoxicity tests can be defined as in vitro and in vivo tests designed to detect compounds which induce genetic damage directly or indirectly by various mechanisms. These tests should enable a hazard identification with respect to damage to DNA and its fixation.

These genotoxicity tests are done to identify if a drug or other substance have the potential to cause mutation and genotoxicity.

Question 18

Comet assay

Answer 18

The comet assay (single-cell gel electrophoresis) is a simple method for measuring deoxyribonucleic acid (DNA) strand breaks in eukaryotic cells.

Allows for the detection of a wide array of DNA damage in single cells with a high sensitivity.

Question 19

Salmonella/mammal microsome (Ames) test

Answer 19

enables detection of the reversed mutations formed in the DNA of Gram-negative enterobacterium Salmonella typhimurium after exposure to a genotoxic substance and to the rat liver homogenate. The number of mutant colonies, able to grow in the histidine-free environment is estimated.

The Ames test shows the number of bacterial cells, which after an exposure to the chemical, have mutated from His- genotype to His+ genotype.

The Ames test is a rapid and reliable bacterial assay used to evaluate a chemical’s potential genotoxicity by measuring its ability to induce reverse mutations at selected loci of several bacterial strains.

Question 20

The following alternative oral acute toxicity animal tests have been developed:

Answer 20

• Fixed Dose Procedure (FDP)
• Acute Toxic Class (ATC)
• Up and Down Procedure (UDP

These methods guarantee significant improvements in animal welfare and permit to reduce dramatically the number of the test animals needed.

Question 21

In water, the biodegradation rate depends on

Answer 21

presence of particulate matter,
concentration of inorganic and organic nutrients,
temperature,
oxygen concentration,
redox potential and
adaptation of the microbial population.

Question 22

In soil, the range and rate of biodegradation depend on

Answer 22

temperature,
soil moisture content,
the composition and activity of bacterial flora,
the properties and “age” of a pollutant and
the content of nutritive ingredients.

Question 23

The rate of photochemical reactions depends on

Answer 23

the number of chlorine atoms in a compound, the more C-Cl bonds, the slower the rate

Question 24

for many PAHs in the aquatic environment photolysis is a major abiotic degradation process, followed by

Answer 24

microbial degradation. Generally, compounds with higher molecular weight and more condensed aromatic rings have a higher rate of photolysis than smaller and less condensed ones.

Question 25

The principal degradation pathways for pesticides involve (4)

Answer 25

photolysis, hydrolysis, dehalogenation and oxidation

Question 26

? is one of the major transformation processes and one of the factors controlling the fate of pesticides in the environment.

Answer 26

Photochemical degradation is one of the major transformation processes and one of the factors controlling the fate of pesticides in the environment. Photodegradation can destroy pesticides on foliage, on the soil surface, and even in the air.

Question 27

Ecotoxicology: Degree of toxic effect can vary depending on

Answer 27

where the organism is found within its food web.

Question 28

Biomagnification is a process which results in

Answer 28

higher concentration of a substance in an organism than in its food. Biomagnification comprises compounds, only slightly soluble in water that tend to accumulate in adipose tissues of an organism.

Question 29

the first harmful effects of a toxicant in a water body often appear as

Answer 29

dead or malformed chicks due to bioaccumulation and egg yolk being rish in fatty material in which toxicants accumulate.

Question 30

(main) 3 Sources of toxic components in feeds

Answer 30

* Environmental, mostly anthropogenic (industrial) pollutants, formed during burning of fossile fuels, industrial emissions, agriculture, nuclear disasters * Toxic metabolites of microorganisms (mycotoxins) * Endogenous toxic compounds of plants, part of which are synthesized for defence against herbivorous animals and other plants

Question 31

name 3 main Environmental contaminants in feeds

Answer 31

Heavy metals. Contamination of feeds/ herbage with Cd (cadmium) is a result of applying certain fertilizers to crops and pastures, with Pb from industrial and urban pollution, Hg from use of fishmeal. Pesticide residues that may contaminate feeds originate from most of the major groups, including organochlorine, organophosphate and pyrethroid compounds. 21 percent of feeds in the UK contain pesticide residues. Dioxins and polychlorinated biphenyls (PCBs) exemplify industrial pollutants that may contaminate feeds, particularly herbage. Cows, grazing pastures that are close to industrial areas produce milk with higher dioxin content.

Question 32

Fungal contaminants in feeds the predominant genus in dairy is

Answer 32

In the tropics, Aspergillus is the predominant genus in dairy and other feeds. Other species include Penicillium, Fusarium and Alternaria, which are also important contaminants of cereal grains.

Question 33

Fungal contamination is undesirable because of

Answer 33

the potential for mycotoxin production. Mycotoxin binding adsorbents exist for binding the toxins.

Question 34

Plant toxicants in feeds may be divided into:

Answer 34

a heat-labile group a heat-stable group

Question 35

Probability of transfer of toxic substances from feed to food and the exact movement paths depend on

Answer 35

a complex of physico-chemical properties of the substance (molecule size, fat solubility or lipophilicity (log Pow), etc), which determine the absorption of the substance into the blood and further into the tissues, the half-life in different parts of the animal's body, metabolism and elimination through different channels, ie. from toxicokinetics and dynamics of the substance, which, from the other side, depend on the animal species and the genetic baggage of a specific individual.

Question 36

What is the log POW?

Answer 36

It is recognized that a simple physiochemical property can be used to indicate a product's potential to bioaccumulate. This property is the Log Pow - defined as the ratio of the equilibrium concentration of a dissolved substance in a two-phase system comprising two largely immiscible solvents, n-octanol and water. if the absorption of a substance from the digestive tract (low logPow ) is approximately 0%, this substance will definitely not reach the tissues. if the substance is completely absorbed, for which the best logPow range is 3-5, it can also reach several edible tissues

Question 37

Transfer factor (TFi) =

Answer 37

the residue concentration (Ci) in the animal commodity of interest (muscle, fat, liver, kidney, milk, eggs) divided by the residue concentration (Cfeed) in the animal feed including any contribution from ingested soil TFi = Ci / Cfeed

Question 38

Food toxicology as a branch of toxicology investigates

Answer 38

ways and mechanisms of entrance of potentially toxic substances into food or their generation during food processing and storage, and the ways of avoiding or reducing food contamination * methods of assessment of toxicity and risk of food components are investigated * adverse effects on an organism produced by harmful components of foods are also investigated

Question 39

Lectins are

Answer 39

nonenzymatic thermolabile glyco- or lipoproteins that selectively bind to saccharide (glucose, galactose, etc.) groups, discovered in more than 800 edible plants. * are widely represented in the leguminous plants (pulses) (Leguminosae) like beans or peas. have also been found in animals like sponges, molluscs, fish (in blood), amphibians (in the eggs), and in mammalian, including human, tissues.

Question 40

Since many, but not all, lectins are capable of agglutinating erythrocytes and other cells, they are often also called

Answer 40

hemagglutinins. In practice, lectins are used for blood group typing, recognition of tumor cells, for investigation of signal transmission, mitogenesis, and cell death.

Question 41

General adverse effects of lectin ingestion is caused by

Answer 41

binding of the molecules to the intestinal membranes. This binding is followed by a nonspecific inhibition of both active and passive transport through the cell wall of important nutrients like amino acids, fats, vitamins, minerals, and necrosis of the cells of the intestinal epithelium. Long-term consumption of raw legumes may lead to growth retardation and even goiter. An acute systemic exposure to the lectins may cause a fatal injury of liver and other organs.

Question 42

Many lectins are destroyed by

Answer 42

normal cooking, but many are not. Wheat germ lectin will resists heating 100°C (212°F) for 30 minutes. Cooking-resistent lectins are also found in apples, carrots, wheat brans, canned corns, pumpkin seeds, bananas, and wheat flour. The clumping abilities of bananas agglutinin are actually enhanced by heating.

Question 43

Concanavalin A (Con A) is a

Answer 43

toxic lectin a protein with potent antinutritional and toxic properties, a component of the jack bean (Canavalia ensiformis). Con A enhances the shedding of brush-border membranes and decreases villus length, thereby reducing surface area for absorption in the small intestine. The overall effect is reduced nutrient absorption, immune function may also be impaired

Question 44

Phytohemagglutinin is

Answer 44

a toxic tectin found in the highest concentrations in uncooked red and white kidney beans.). Can cause poisoning in monogastric animals through the consumption of raw or improperly-prepared kidney beans. Effect can be reduced to safe levels by boiling for at least 30 minutes at 100°C. Insufficient cooking, at 80°C, raises the toxicity up to fivefold. Poisoning can be induced from as few as five raw beans, symptoms occur within 3 hours, with nausea, then vomiting, which can be severe and sustained (profuse), followed by diarrhea. Recovery within 4-5 hours of onset, usually without the need for any medical intervention

Question 45

two Particularly toxic lectins are

Answer 45

ricin in the seeds of castor bean (Ricinus communis) & abrin in the seeds of jequirity bean (Abrus precatorius). Hepato- and nephrotoxic and generate oxidative stress. Perorally cause acute necrosis of the cells of GIT and death through multiorgan failure.

Question 46

Out of enzyme inhibitors, the most important ones toxicologicallly are

Answer 46

protease inhibitors These extremely proteolysis-resistant proteins are found in all plants, but in larger quantities in legumes They are mostly inhibitors of a serine protease trypsin, but inhibitors of chymotrypsin and carboxypeptidase B have also been found. Thermal processing usually denaturates the inhibitor molecules.

Question 47

Toxicologically most interesting cyanogens are (4)

Answer 47

amygdalin, dhurrin, linamarin and lotaustralin

Question 48

Cyanogenic glycosides are 20 glycosides of a low toxicity that release

Answer 48

highly toxic hydrocyanic acid (HCN) at their enzymatic hydrolysis, found in many plants (over 300 species), but also in mushrooms, bacteria, and animal.

Question 49

The most well-known and widely spread cyanogenic glycoside is

Answer 49

amygdalin found in e.g. almonds and apricot stones Is an odorless and bitter substance, readily soluble in water and ethanol.

Question 50

cyanogenic glycoside linamarin is found in (2)

Answer 50

Linseeds and leaves and roots of cassava

Question 51

How much linseed would you need to kill a horse by linamarin toxicity?

Answer 51

3 kg Two-month-old lambs died after eating 125 g linseed flour per day. Adult cows are less sensitive to linamarin since cyanic acid is bound in their rumen.

Question 52

Why is cyanic acid so toxic?

Answer 52

The acute toxicity of HCN originates from its high affinity to the enzymes containing metalloporphyrin unit, especially to cytochrome oxidase. Very low concentrations (33 μM) can prevent the use of oxygen for the synthesis of ATP through a complete blocking of the mitochondrial electron transport chain.

Question 53

Alkaloids are

Answer 53

nitrogen-containing heterocyclic compounds that exert a pharmacological effect in humans and animals. They defend plants against herbivorous animals, parasites and insects. Alkaloids, due to alkaline properties, form salts with acids.

Question 54

In case of animals, important alkaloids are

Answer 54

quinolizidine alkaloids, occuring in lupins (lupiini) and including lupinine, and sparteine. cattle, consuming certain lupin species during pregnancy may produce calves with multiple congenital deformities (teratogenicity).

Question 55

4 important classes of alkaloids

Answer 55

pyrrolizidine (ragwort) solanine, xanthine and ephedrine alkaloids

Question 56

what substances are found in tomatoes and potatoes, that can cause toxicity on excessive consumption?

Answer 56

glycoalkaloid tomatine & glykoalkaloids α-solanine, α-chaconine in potatoes

Question 57

The acute toxic effect of glycoalkaloids consists of two parts

Answer 57

1. Effect on the nervous system, based on the inhibition of the cholinesterase-group enzymes 2. Solanine and chaconine destroy the membranes of erythrocytes and other cells

Question 58

Name 3 Xanthine alkaloids

Answer 58

The xanthine-subgroup of purines includes closely related alkaloids such as caffeine, theobromine, and theophyllin, the main alkaloid components in the seeds of coffee beans, in the seeds of the cocoa tree (Theobroma cacao); in the leaves of the tea plant (Camellia sinensis – earlier thein).

Question 59

Ephedrine alkaloids are structurally very similar to

Answer 59

adrenaline/epinephrine the mechanism of action of ephedrine alkaloids is based on the same similarity. As an adrenaline agonist, ephedrine causes a sympathomimetic effect that triggers heart acceleration, a rise in blood pressure, and stimulation of the CNS. A single dose of 2 g is lethal for any adult person. most countries have banned the use of ephedrine alkaloids as food additives

Question 60

Coumarin is a constituent of

Answer 60

several essential spices like cinnamon. Coumarin is found in large concentrations in the oil of cinnamon tree. The use of coumarin as a food additive was stopped after discovery of its hepatotoxicity to rats and mice. However, that metabolic systems of humans and rat treat coumarin differently. The main metabolite, formed with CYP is 3,4- epoxide of coumarin, which is the actual culprit of the coumarin’s both acute and chronic toxicity. Recently, the former decisions concerning coumarin were revised by EFSA, which set the TDI value to 0.1 mg/kg bw. The estimated maximal daily dietary consumption of coumarin is 0.07 mg/kg or 0.02 mg/kg, according to a more realistic scenario. Since both these numbers are smaller than TDI, the removal from market of at least part of the coumarin-containing products turned out to be unnecessary.

Question 61

Phytoestrogens (PE) are

Answer 61

plant compounds that both structurally and functionally resemble to 17β-estradiol and, hence, bind to estradiol receptors. Although their affinity for binding is 20–200 times less than that of estradiol, they compete with estradiol for receptor sites. It results in 500–10,000 times weaker in vivo estrogenic effect than the effect of an endogenous estrogen. As a result, PE are able to act as both agonists and antagonists of estradiol. Their content in plants is the highest during blossoming

Question 62

flavonoid

Answer 62

are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. There are four main groups of phytoestrogens: isoflavonoids, flavonoids, stilbenes, and lignans.

Question 63

In clover, the major form of PE that is

Answer 63

formononetin is the major form of PE that is converted into a more estrogenic metabolites.

Question 64

Coumestans like coumestrol are

Answer 64

phytoestrogens found in legumes and clover

Question 65

Glucosinolates (previously known as thioglucosides) are

Answer 65

are sulfur-containing phytochemicals found in cruciferous or brassica vegetables, such as broccoli, cabbage, kale, cauliflower, and Brussels sprouts. Biological activity is caused by both the initial compounds and compounds like isothiocyanate (mustard oil), nitrile, oxazolidinthione (OZT), and thiocyanate ions, formed from glucosinolates in the human GIT by the bacterial myrosinase. Like most proteins, myrosinase is denatured during boiling. Thiocyanate ion (SCN-) inhibits assimilation of iodine by the animal thyroid gland.

Question 66

Isothiocyanates exert a

Answer 66

embryocidal effect and cause a weight reduction of embryos. Isothiocyanates and some glucosinolates (e.g., sinigrin), but not thiocyanates, are mutagenic in the Ames test. Due to electrophilic properties, some isothiocyanates form adducts with DNA inducing gene mutations and chromosomal aberrations.

Question 67

favism

Answer 67

is a genetic disease involving a deficiency in glucose-6-phosphate dehydrogenase (G-6-PD), an enzyme that is essential for the survival of red blood cells. This enzyme deficiency primarily affects male populations. Favism is when someone has a very severe reaction to fava beans (broad beans). They are at risk of acute haemolysis, in which their red blood cells break down faster than the body can replace them. This can be life-threatening. Some people with favism are even at risk when exposed to pollen from the fava plant. Cooking abolishes the hemolytic effect of the beans.

Question 68

Deficiency of G6PD is

Answer 68

the disease called favism in which a severe reactions to certain beans occurs (even fatal). the most abundant enzyme deficiency, affecting about 400 million people worldwide (mostly men). Favism is widely distributed among the Jews of Israel and Greeks of Cyprus, in the Near East and in China, in tropical Africa. Is almost unknown for the nations of the North Europe and the Indians of the North America.

Question 69

G6PD-deficiency is one of the three genetical disorders, connected with erythrocytes that guarantee

Answer 69

tolerance to the malaria parasite (Falciparum malaria). The other two are thalassemia (body doesn't make enough hemoglobin) and sickle-cell anemia.

Question 70

what is erucic acid (EA) and in what is it found

Answer 70

is a 22-C monounsaturated fatty acid (MUFA). Rapeseed and mustard oils and other seed oils of Brassica genus contain erucic acid (EA) The health-damaging effects of erucic acid include fatty degeneration of the heart (myocardial lipidosis), during which fats (lipids) accumulate in the heart tissue.

Question 71

Canola is a

Answer 71

low erucic acid species of rapeseed, EA content in seeds below 0.5%, developed in Canada. Rapeseed oil intended for human food in EU cannot contain more than 5% of EA from total content of fatty acids.

Question 72

Epoxide definition

Answer 72

an organic compound whose molecule contains a three-membered ring involving an oxygen atom and two carbon atoms.

Question 73

Toxic pigment gossypol occurs in

Answer 73

cottonseed in free and bound forms. It also occurs in leaves, stems and flower buds of the cotton plant. In whole seeds, gossypol exists essentially in the free form, but variable amounts may bind with protein during processing to yield inactive forms. Free gossypol is the toxic form. Decomposes during heating.

Question 74

Free gossypol causes

Answer 74

organ damage, cardiac failure and death of swine, dogs, goats, cattle, pre-ruminant calves, and lambs. Dairy cows are particularly susceptible to gossypol toxicosis. the most common toxic effect is the impairment of male and female reproduction. Cottonseed meal fed to bulls can induce sperm abnormalities and decrease sperm production.

Question 75

Oxalic acid is

Answer 75

a strong acid that irritates tissues. Moreover, oxalates form tiny insoluble crystals with sharp edges, which also irritate tissues. High levels of oxalic acid/oxalates in the diet may cause adverse effects on the digestive system, particularly of the stomach, and kidneys. Oxalates may also contribute to the formation of calcium oxalate stones in the kidneys.

Question 76

Oxalic acid chelates

Answer 76

blood Ca, resulting in hypocalcemia, coagulation disorders and tetany. Oxalates may also contribute to the formation of calcium oxalate stones in the kidneys.

Question 77

Oxalates are found in

Answer 77

Rhubarb, spinach, parsley, chives, purslane, cassava, amaranth, beet leaves, taro leaves, radishes, collards, tea, and cocoa contain a large amount (0.3–2.0% ww) of oxalic acid. However, in order to get the lethal dose of oxalates, one should eat either 5 kg of rhubarb, 2.5 kg of tomato or 0.5 kg of spinach leaves.

Question 78

lutein

Answer 78

Lutein is one of two major carotenoids found in the human eye (macula and retina). It is thought to function as a light filter, protecting the eye tissues from sunlight damage. Foods rich in lutein include egg yolks, spinach, kale, corn, orange pepper, kiwi fruit, grapes, zucchini, and squash.

Question 79

bracken

Answer 79

a tall fern with coarse lobed fronds, which occurs worldwide and can cover large areas. is the only known higher plant causing cumulative animal cancers. Regardless of that, its rhisome, rich in starch, is used for food in several places like New Zealand. The rhizome is also used in brewing beer and for preparation of an excellent paste. It is supposed that the wide distribution of gastric cancer in Japan is caused by a widespread practice of eating bracken.

Question 80

Bracken as a fodder component

Answer 80

Eating of bracken by herbivorous animals causes both acute and chronic toxicity syndromes.

Question 81

Both an incomplete and excessive use of vitamin A and nicotinic acid may cause

Answer 81

teratogenesis. Still, no problems of teratogenicity have occurred at the daily doses below 10,000 IU.

Question 82

Vitamin A is an antipromoter of

Answer 82

cancer that is, by inhibiting the pathological division of cells, prevents formation of skin, lung, bladder, breast, esophageal, and stomach cancer in test animals.

Question 83

parent compounds of retinol are for example

Answer 83

carotenoids found in many plants

Question 84

β-carotene, found in

Answer 84

carrots and in all chlorophyll-containing foods, inhibits cancers of the large intestine and pancreas of rats, skin cancer induced by UV-radiation of mice, and so on

Question 85

Carotenes are good scavengers of

Answer 85

free radicals as well as quenchers of singlet oxygen causing lipid peroxidation (LPO), are potent antioxidants. Especially outstanding in this sense is β-carotene.

Question 86

lycopene, the red pigment of tomato fruits is a potent

Answer 86

antioxidant and anticarcinogen

Question 87

The health promoting daily dose of β-carotene, solely from natural sources, is 10 mg. The lowest daily dose causing adverse effects on the smokers is 20 mg. Very close to each other. The reasons why β-carotene acts so,

Answer 87

are not fully understood yet. According to one of the hypotheses, β-carotene induces the metabolic phase I enzymes, particularly CYP that, in turn, activates the potential carcinogens of cigarette smoke as well as other secondary carcinogens.

Question 88

calciferols, also known as what? are what?

Answer 88

vitamin D is a group of fat-soluble hormonal substances with an antirachitic effect and similar structure that only historically belong among vitamins. antirachitic effect meaning = used or tending to prevent or cure rickets. the antirachitic activity of vitamin D.

Question 89

Vitamin D3 or

Answer 89

cholecalciferol is formed in the skin

Question 90

vitamin D2 or

Answer 90

ergocalciferol is formed from ergosterol. Both metabolites are responsible for absorption of calcium from the intestines and accumulation in the organic part of the bones by stimulation of the synthesis of the calcium-binding protein.

Question 91

Absorption of vitamin D from intestines is most efficient in

Answer 91

composition of lipid micelles by passive diffusion via lymph. Vitamin D has special carrier molecule DBP to be transported from liver to target organs by bloodstream.

Question 92

The lethal dose of vitamin D for dogs is

Answer 92

13 mg/kg for dogs.

Question 93

Food adulteration is the

Answer 93

intentional debasing of the quality of food intended for sale either by the admixture or substitution of inferior substances or by the removal of a valuable ingredient.

Question 94

Food adulteration is carried out with the aim of

Answer 94

reduction of the manufacturing costs or for some other deceptive or malicious purpose. A food adulterant is a chemical substance or composition added to food during adulteration.

Question 95

Food is declared adulterated if: (4)

Answer 95

* a substance or composition is added which depreciates or injuriously affects food * cheaper or inferior substances are substituted wholly or in part * any valuable or necessary constituent has been wholly or in part subtracted * it is colored or otherwise treated, to improve its appearance or if it contains any added substance injurious to health

Question 96

Well-known, but insignificant from toxicological point of view food adulterations (falsifications) are (4)

Answer 96

* injection of water or brine into meat to increase its weight * diluting of milk and beer and hard drinks with water * adding of starch to sausages * roasted chicory roots, or seeds to produce cheaper coffee.

Question 97

Melamine is one of the most effective

Answer 97

food adulterants used to increase the nitrogen content in foods and feeds. MEL contains about 66.6 % of nitrogen, and the addition of 1% melamine leads to a false increase in the protein content, measured by Kjeldahl method, by 4.16%.

Question 98

A sharp increase in urinary tract stone formation in infants was registered in China in 2008. What compound was this due to?

Answer 98

melamine, food adulterant

Question 99

cyanuric acid is contained in

Answer 99

mixtures used for cleaning and disinfection of milk pipelines in dairy farms as a hydrolysis product of dichloroisocyanurates. In case of insufficient rinsing of the pipelines with water, there is a risk of contamination of milk with cyanuric acid.