Download v. assessment of uncertain results

LLP “OO KAZAKH ACADEMY OF NUTRITION”
RSE "Scientific and Practical Center of sanitary-epidemiological examination
and monitoring” of the Ministry of Health of the Republic of Kazakhstan
MATERIALS FOR HUMAN HEALTH RISK ASSESSMENT OF
TETRACYCLINE INTAKE WITH FOOD
Almaty, 2013
1
Content:
INTRODUCTION………………………………………………………………….3
I. HAZARD IDENTIFICATION………………………………..…………………4
1.1 Body distribution……………………………………………………………6
1.2 Main effects………………………………………………...……………….6
II. HAZARD STATEMENT………………………………………..…………….10
2.1 Permissible exposure limit……………………………..………………….10
2.2 "Exposure-effect" dependency evaluation……………………………….12
III. EXPOSURE SSESSMENT…………………………………………………..14
IV. RISK SSESSMENT…………………………………………………………16
V. ASSESSMENT OF UNCERTAIN RESULTS…………..…………………..22
CONCLUSION…………………………….…………………………………….23
REGERENCE LIST……………………………………………………….…….24
2
INTRODUCTION
Tetracyclines are broadly used antibacterial drugs that unite a group of
substituted polyoxy-polycarbonyl hydroaromatic compounds which have the same
structure and produced by bacteria of Streptomyces type. Due to chemical
modification of these substances semisynthetic tetracyclines are obtained [1,2].
Basic tetracycline compounds were produced in 1948-1952. Main characteristics
of representatives of this family are a general spectrum and mechanism of
antimicrobial action, whole crossed resistance and close pharmacological
characteristics.
The differences relate to the degree of antibacterial effect,
peculiarities of absorption, distribution, metabolism in the body, tolerability and
some physicochemical properties [3]. 35 compounds of this group are described.
According to the mechanism of biological action tetracyclines belong to the
group of antibiotics that inhibit protein synthesis. Tetracycline within bacterial
cells is an inhibitor of protein chain elongation and it prevents binding of another
aa-t RNA.
Tetracycline antibiotics are used in the treatment and prevention of bacterial
infections of both human and animals. In animal husbandry, they are used as
therapeutic and veterinary drugs, and growth promoters [4].
Tetracycline used as growth promoters in animal husbandry increase body
weight by an average 4.5%, costs of feed per unit of gain is reduced by 5-8%,
activates body's resistance and reduces animal feeding season. Intake of these
products by poultry stimulates their increase, egg production, hatching egg quality,
and contributes to a more efficient use of feed and better uptake of protein [5].
From the viewpoint of food hygiene the main danger of antibiotic residues
for human is that it can get into human body through feed together with the
agricultural products, which negatively affect intestinal microflora, lower
resistance to infections, and increase resistance to antibiotics [4].
The legislation of the European Union, the USA, norms and standards of the
Codex Alimentarius differ significantly in measurement of residual amount of
3
tetracycline (MRLs ≤0,1-1,2 mg/kg), which in its turn differ significantly from the
requirements of the Customs Union regulations (≤0,01 mg/kg of product). Thus,
according to the Codex Alimentarius and the EU legislation milk is normalized by
no more than 100 µg/kg, in the United States it is not regulated, in the countries of
the Eurasian Customs Union (CU) it is not accepted.
This scientific work is done in accordance with the practical principles of risk
analysis in terms of food safety, which can be used by governments of the Codex
Alimentarius Commission (CAC/GL 62-2007) [45].
I. HAZARD IDENTIFICATION
Hazard identification of tetracycline residues is carried out on the basis of
results of various research studies available in the scientific literature, including
those conducted in respect to humans.
Tetracycline antibiotics amount to over 52% of all antibiotics used in animal
husbandry and veterinary medicine in Europe [6].
Tetracyclines have a bacterial
growth-inhibiting action in therapeutic dose.
In animal husbandry the semisynthetic tetracyclines based on oxy- and
chlortetracycline are used, including tetracycline carboxamide derivatives with a
prolonged effect. They have several distinct properties, which include high
solubility in water at various values of pH (2,0 -8,5), fast absorption in gastrointestinal tract, higher concentration in the blood stream during the first hours after
their administration.
Antibacterial action of tetracyclines is based on suppression of protein
synthesis due to dyspoiesis of a complex between soluble RNA and ribosome.
Tetracyclines are active with respect to gram-positive organisms:
Staphylococcus spp. (including Staphylococcus aureus, including producing betalactamase strains), Streptococcus spp. (including Streptococcus pneumoniae),
Listeria spp., Bacillus anthracis, Clostridium spp., Actinomyces israelii; gramnegative micro-organisms: Haemophilus influenzae, Haemophilus ducreyi,
4
Bordetella pertussis, most enterobacteria: Escherichia coli, Enterobacter spp.,
including Enterobacter aerogenes, Klebsiella spp., Salmonella spp., Shigella spp.,
Yersinia pestis, Bartonella bacilliformis, Vibrio cholerae, Vibrio fetus, Rickettsi
spp., Borrelia burgdorferi, Brucella spp., they are also active with respect to
pathogens of venereal lymphogranuloma, Treponema spp. These micro-organisms
are resistant to tetracycline: Pseudomonas aeruginosa, Proteus spp., Serratia spp.,
most strains Bacteroides spp. and mold fungi, viruses, beta-haemolytic
streptococcus of А-group (including 44% of strains Streptococcus pyogenes and 74
% of strains Streptococcus faecalis) [7.]
1.1 Body distribution
During parenteral administration tetracycline is well absorbed and penetrates
into many organs and tissues. It poorly penetrates through the intact blood-brain
barrier, but in case of cerebrosis and disease of brain membranes its concentration
significantly increases within cerebrospinal fluid. Plasma binds with protein by
65%. It is selectively accumulated in bones, teeth, liver, spleen, and tumour tissues
in significant numbers. It easy penetrates through the placental barrier and is
excreted in breast milk.
After intake 60-80% of the dose is absorbed from the gastrointestinal tract. It is
cleared through the urine and fecal remaining unchanged (fecal - 20-50%, urine 20-69%). In case of disorder of excretory function of the kidneys, tetracycline
concentration in blood increases, which can lead to accumulation [8].
Lipophilic doxycycline has 2-3 times longer half-life elimination compared
to tetracycline. Despite good blotting capacity in digestive tract, residual
tetracycline concentration in gut is always sufficient to affect the intestinal
microflora [7,10].
1.2 Main effects
When a single dose of tetracycline equal to 75mg / kg was administered to white
rats, plasma peak concentration (up to 3.6 mg/l) were identified in 2 hours after
5
administration, which decreased by 0.5 mg/l in 6 hours. Peak concentration in their
liver and kidneys were identified in 2 hours after administration of that [9].
While intravenous injection of tetracycline hydrochloride (10 mg / kg) to dogs, the
highest level was identified in its liver and kidneys. In case of peroral
administration to dogs at a dose of 25 mg/kg, peak concentration amounted to 3
mg/ml in 2 hours, which reduced to a level of 0.27 in 24 hours after administration
[11].
Antibiotics mainly excreted through the urine. Within 72 hours after intravenous
administration of tetracycline to 2 rats and 1 dog in a dose of 15 mg or 4 mg/kg,
respectively, 69.2% and 19.5% of antibiotics was identified in the urine [9].
High doses of tetracycline at the level of 2500 up to 7500 mg/kg of body weight
may reduce the body weight and cause limited adiposis in rat’s liver [12].
Gonadotoxic, embryotoxic, teratogenic, mutagenic and carcinogenic effects of the
doses studied have not been found. [13] It is noted that while raising the dose of
the preparation injected, the content of tetracycline in bone tissue and its
pigmentation also increases [14].
Within human body tetracycline is better absorbed in gastrointestinal tract (up to
66% of the dose taken). Maximum drug concentration appears in blood serum in 13 hours after ingestion. A significantly higher concentration may be achieved
during intravenous injection.
Абсорбция антибиотиков группы тетрациклина различается у человека
и животных,
показателей
составляя только
имеющих
4-9% у мышей и крыс [13]. Среди
значительные
различия
между
человеком
и
животными можно назвать:
Absorption of tetracycline antibiotics of humans and animals is different, which
accounts for 4-9% only for mice and rats [13]. Among the indicators that
significantly differ between humans and animals there are:
-
number
-
time
of
during
antibiotic
which
absorbed
body
collects
in
the
antibiotic
gastrointestinal
peak
tract;
concentrations;
- localization of antibiotic peak concentrations within the body;
6
- time during which antibiotic is cleared from the body.
These differences must be considered in case of extrapolated results obtained
from experiments, where laboratory animals were involved with respect to
humans.
If antibiotic gets in the human body the effects made on pathogenic flora
cannot define its action, but it involves obligate and facultative intestinal
microflora, causing a state of dysbiosis. Antibiotics also interact with the human
body, which depending on the dose provides development of adverse changes at
metabolic, morphological and functional level. [15].
Development of resistance to antibiotics and further transfer of the
tetracycline-resistant strains of micro-organisms to human represent the major
health concern. The pollution risk of food stock caused by antibiotic residues
directly relates with development of microbial resistance. Both livestock and
poultry, and crop production pollute antibiotics. Antibiotics cleared from animal
organisms get into soil as organic fertilizers and then they accumulate in plant
products. Nowadays representatives of both pathogenic and opportunistic
microorganisms have polyresistance to antibiotics. Frequently, salmonella is the
reason of hospital acquired disease and food poisoning. Antibiotic resistance was
observed more frequently among salmonella found in humans, than among that
found in farm animals and birds. In addition, 49.1% showed resistance to
tetracycline [16]. It was shown that among clinical strains of microorganisms,
enterobacteria had the highest percentage of antibiotic resistance. Strains are the
most common among gram-negative micro-organisms, which are resistant to drugs
9-11 that is confirmed by data obtained in the Kazakh Academy of Nutrition from
1986 to 1999. Almost within all human waste there are antibiotic-resistant bacteria
that can survive selectively during intake of the relevant drugs. (18).
Normal microflora as human symbiont plays important role to support life of the
organism and ensure its homeostasis.
Proportion of species of intestinal microflora can be changed due to influence of
tetracycline, even some or almost all the indigenous (autochthonous) strains can
7
disappear completely and opportunistic pathogens may rapidly multiply. Such
changes are called dysbiosis [20, 21, 22, 23, 24, 25].
In medical practice, according to the International Classification of Diseases, Tenth
revision [26], a number of diseases associated with an imbalance of intestinal
microflora was identified: irritable bowel syndrome (IBS) with diarrhea (K58.0)
without diarrhea (K58.9), constipation (K59.0), inflammatory bowel disease (IBD)
(K50-K51).
Microflora imbalance can often trigger development of pathology in various
systems and organs, and cause secondary immunodeficiency states and compound
the course of various diseases of infectious and non-infectious ethiology.
[27,28,29,30,31,32,33].
It is considered that children that have the intestinal microflora imbalance, in
addition to the above mentioned diseases can have: functional bowel disorder
(K59.9), duodenitis (K29.8, K29.9), food allergy (T78.0, T78.1, T78.4), including
atopic
dermatitis
(L20.8),
iron
deficiency
anemia
(D50),
a
general
immunodeficiency (D83.9) [34,35,36].
Ingestion of antibiotic residues and tetracyclines, in particular, may represent
effects of chemical factors of low intensity. Such stress on human body can cause
long-term effects, and reduce body's resistance to adverse environmental and
socially environmental factors.
Generally, there are many scientific evidences collected that underestimate
impact depth of small doses of biologically active xenobiotics of anthropogenic
origin. First, this is applied to tetracyclines, which reduce the adaptive capacity of
people by affecting the environment and reducing the indicators of their sanitary
and epidemiological welfare [37].
II. HAZARD STATEMENT
2.1 Permissible exposure limit
8
In 2006, the Expert Committee on Food Additives of FAO / WHO revised
the acceptable daily intake of tetracyclines and changed it from 0-3 mg per kg of
body weight per day to 0-30 mg per kg of body weight per day [26]. In 1990,
when the acceptable daily intake was established (0-3 mkg per kg of body weight
per day) an uncertainty factor at 10 was accepted due to variability of intestinal
flora of humans. And it was assumed that the actual acceptable daily intake can
be a little higher than the fixed one.
Results of in vitro experiments about the dosage study, which is equivalent
to 0,025; 0.25 and 2.5 mg/kg of body weight became the reason for revision. Based
on these studies, it was concluded that the variability among individuals is small
and now it is useless to apply uncertainty factor, therefore, the acceptable daily
intake should take should be 0-30 micrograms per kg of body weight per day [37].
However, this decision is considered to be unproven due to reasons specified
by the Russian FBSI "Federal Research Centre for Medical and Preventive
Technologies of Public Health Risk Management"
1. Acceptable daily intake is established for food consumption terms on a daily
basis throughout the whole life and it cannot be based on data, obtained during the
short-term experiment in vitro without having a proper analysis of uncertainty that
considers transfer of results obtained from in vitro experiment made on human,
including data of short-term studies about influence through the whole life [28,
29].
2. According to formula (1), recommended by FAO/WHO [29], we calculated
acceptable daily intake of tetracycline and oxytetracycline for various types of
micro-organisms.
(1)
9
ADI = MIC50 x Mass of intestinal contents excreted (220 g) / Dose inhibiting the microorganisms growth x Margin factor x Individual’s weight (60 kg) while peroral administration
Formula was developed based on modal value MIC50 (MIC50 – minimum
antibiotic concentration, inhibiting increase of 50% cultures of certain microorganisms), margin factor to consider various types of variability, mass of
intestinal contents, individual's weight and peroral dose of antibiotics, inhibiting
micro-organisms growth.
MIC50 values of tetracycline and oxytetracycline for 10 different micro-organisms
were taken in accordance with WHO Food Additives Series 36, the margin factor
value - 1, a dose that inhibits the microorganisms growth during peroral
administration of tetracyclines - 0.6 mg, the mass of intestinal contents excreted 220g, and the average individual's weight - 60 kg.
According to formula (1) the acceptable daily intake of tetracyclines
obtained from minimum inhibitory concentration (MIC50) for some microorganisms ranged from 0.37 mg/kg of body weight in terms of Clostridium spp. to
195.6 mg/kg of body weight for Escherichia coli and Proteus spp. (Table 1). This
high variability of results may indicate the need to include the acceptable daily
intake of additional uncertainty factor into calculation, especially for the most
sensitive groups of people, such as children.
While carrying out health risk
assessment considering the characteristics of these groups, they should be noted,
including dismaturity of local gut-associated immunity of infants, chronic
gastrointestinal diseases, changing immune status, gastrointestinal microbocenosis
disorders, and dietary habits of people.
Table 1
Micro-organism
Escherichia coli
Bifidobacterium spp.
Bacteroides fragilis
Dose that cause
microbistatic mcg / kg
195.56
97.78
24.44
10
Eubacterium spp.
Clostridium spp.
Streptococcus spp.
Fusobacterium spp.
Lactobacillus spp.
Proteus spp.
Peptostreptococcus spp.
12.22
0.38
97.78
0.76
12.22
195.56
12.22
3. Results of the experiment in vitro became the reason why use of uncertainty
factor was rejected while determining ADI (ADI) of tetracyclines [26]. It was
shown that concentrations were studied, which were equal to doses of 0.025; 0.25
and 2.5 mg/kg of body weight and it was concluded that doses of 0.025 and 0.25
mg/kg of body weight are invalid. And we couldn't establish how equality of doses
to levels of exposure to chemostat microflora was evaluated. Evaluation of the
proposed ratio using the formula 1 showed that the results were inconsistent. This
proves the high uncertainty of data, based on which there is not enough motivation
in order to reject the proposed modifying factor of 10 and the acceptable daily dose
of 3 mg/kg of body weight [37,38].
2.2 "Exposure-effect" dependency evaluation
Development of intestinal microflora imbalance due to tetracycline
Относительная численность кишечной
микрофлоры, %
concentration according to research studies in vitro shown in Fig. 1.
100%
Бифидобактерии
90%
Лактобактерии
80%
70%
Бактероиды
60%
2%
50%
1%
40%
0%
Фузобактерии
Пептострептококки
0
30%
5
10
15
20
25
30
35
20%
E.Coli типичные
Факультативная
флора
10%
Клостридии
0%
0
5
10
15
20
25
30
35
концентрация, мкг/мл
11
Figure 1 - The dependence of the relative abundance of the intestinal
microflora (%) on the concentration of tetracycline
Changes in the ratio of facultative and obligate intestinal flora are presented in
Figure 2.
100%
90%
Доля факультативной флоры
Share of
facultative flora
80%
70%
60%
50%
40%
30%
20%
10%
0%
0%
20%
40%
60%
80%
100%
Shareоблигатной
of obligate flora
Доля
флоры
Figure 2 - Tthe ratio of facultative and obligate intestinal microflora
Data of research studies on diseases associated with an imbalance of intestinal
microflora of adults and children have shown that changes in composition of
intestinal microflora for adults result in:
dysbiosis 1st degree – from 18,6 to 34,8%,
dysbiosis 2nd degree – from 24,2 to 45,7%,
dysbiosis 3rd degree – from 27,0 to 56,3%.
For children:
dysbiosis 1st degree – from 2,0 to 74,0%,
dysbiosis 2nd degree – from 26,0 to 84,0% and
dysbiosis 3rd degree – from 0,0 to 39,1% [39, 40, 45, 46].
III. EXPOSURE ASSESSMENT
12
The exposure assessment was provided on the base of maximum residue
level (MRL) of tetracycline for different animal origin food stuff groups taking
into the account the daily consumption average level of corresponding foods.
Thus according to the Sanitary Regulations and Standards of the Republic of
Kazakhstan from 2001 and according to the data from the ‘Agency of Statistics of
the Republic of Kazakhstan’ the following the daily animal origin food content is
received into the food basket for different age groups of citizens of the Republic of
Kazakhstan (table A1).
Table А1
The daily animal origin food content in the food basket for different age
groups of citizens of the Republic of Kazakhstan (gram/day).
Products
Meat and meat products
Until
3
years
old
65
From 3
to 7
years
old
100
School aged
Teenagers
Adults
95
100
150
635
570
570
592
579
17
17
25
30
55
15
15
17
764
27
50
25
789
27
60
35
812
55
100
50
927
38
185
70
1084
Milk, fermented milk
products
Poultry and poultry
products
Egg
Fish and seafood
Animal oils and fats
Total
Values of maximum residue levels of tetracycline for adults, for different
types of animal tissues and exposition types, recommended by WHO (1990),
FAO/WHO (1998) and accepted in the USA. (Table А2).
Table А2
MRL values for various types of animal tissues and exposition types
Food
Milk, mkg/l
Soft tissue, mkg/kg
Fat tissue, mkg/kg
Eggs, mkg/kg
Liver, mkg/kg
Kidney, mkg/kg
ТС
WHO
1990
10
10
10
10
10
10
100
100
10
200
300
600
FAO/WHO
1998, Кодекс
алиментариус
100
200
400
600
1200
USA
300
2000
10
200
300
600
13
According to submitted data the maximum daily incoming of tetracycline
with the food staff for different age group citizens of RoK was calculated (Table
A3).
Table А3
The maximum daily incoming of tetracycline with the food staff for different age
group citizens of RoK in mcg/kgs for the value of ТС, WHO (1990), FAO/WHO
(1998)/ CODEX Alimentarius and accepted in the USA.
Until 3
years
old
ТС
WHO (1990)
FAO/WHO (1998)
USA
8.29
86.87
92.17
184.87
From 3
to 7
years
old
7.89
79.45
84.75
393.55
School
aged
Teenagers
Adults
8.12
80.85
86.15
388.85
9.27
103.70
115.70
421.10
10.84
106.60
115.60
542.40
Taking into account the average mass of eliminating content from the
bowel of adults which is 220 gr [46,47], and the average mass of eliminating
content from the bowel of children (50 gr) [47], the concentration of tetracycline in
gastro-intestinal tract is calculated.
Table А4
The concentration of tetracycline in gastro-intestinal tract for the different
age group of citizens of the Republic of Kazakhstan for the values of ТС, WHO
(1990), FAO/WHO (1998) and accepted in the USA.
Until 3
years old
ТС
WHO (1990)
FAO/WHO (1998)
USA
0.17
1.74
1.84
7.70
From 3
to 7
years
old
0.16
1.59
1.70
7.87
School aged
Teenagers
Adults
0.16
1.62
1.72
7.78
0.04
0.47
0.53
1.91
0.05
0.48
0.53
2.47
Thus, the concentration of tetracycline in gastro-intestinal tract of adult
people varied from 0,05 mcg/g to 2,47mcg/g. The concentration of tetracycline in
the gastro-intestinal tract of children varied from 0,16 mcg/g to 7,87mcg/g.
14
The obtained data can be used for calculating the risk characterization of
forming resistant strains of microorganisms in gastro-intestinal tract of people and
distortion of balance of bowel flora with increasing part of pathogenic and
potentially pathogenic strains.
IV. RISK CHARACTERISATION
Using of antibiotics enables the grow of resistant flora both pathogenic and
potentially pathogenic, in this case the high bacterial and bacterio-static activity of
drugs is saved towards the obligate anaerobic flora (bifid bacterium, bacteroid,
clostridium, fusobacterium, peptostreptococcus, lactic bacteria).
Level of potentially-pathogenic (commensal) microflora (Escherichia coli,
Salmonella spp., Campylobacter spp. и Еnterococci) is estimated figure of resistant
induction of bacteria on the back of antibiotics treatment and indirect indicator of
expected resistance of pathogenic flora. Commensal stability monitoring is the
prevalence indicator of antibiotic resistance in population [19].
Forming changes of bowel microbial landscape spectrum on the back of
tetracycline influence in the form of ratio distortion between anaerobic and
aerobiotic flora with growth inhibition of obligatory microorganisms (lactic
bacteria, fusobacterium, peptostreptococcus, clostridium) brings to increasing of
Escherichia coli, Salmonella spp., Campylobacter spp. and Enterococci,
staphylococcus proportion, which shows the bowel microflora disbalance [19, 23,
24,
25,
26].
The assessment of health risk under the tetracycline influence, incoming with
food, was provided separately for each age group. The calculations were conducted
by maximum residue concentrations of tetracycline for four values, recommended
by ТС, WHO (1990), FAO/WHO (1998) and accepted in the USA (Table А4).
In the result of modeling the bowel microflora balance distortion, there was
established that the values, recommended by TC are the most harmless for health
for all the age groups of people at which the content of potentially pathogenic
15
microorganisms is not more than 5% from the total amount of bacteria. The
values, recommended by WHO (1990) and FAO/WHO (1998)/ Codex
Alimentarius are harmless for only two age groups (teenagers and adults). The
values of residue tetracycline in the animal origin food, recommended by WHO
(1990) and FAO/WHO (1998) are dangerous to health of children up to 3 years
and from 3 to 7 years.
The realization of values, recommended by WHO (1990) and FAO/WHO
(1998) and accepted in the USA can be related to inhibiting obligatory microflora
and brings to bowel microflora disbalance of different heaviness. (Tables А7, А8
and А9).
According to the WHO data, the minimum inhibiting concentration of
tetracycline Mic90 (the concentration at which the 90% of bacteria is inhibited) was
determined.
In the Table A5 the composition of normal microflora and the minimum
inhibiting tetracycline concentration data is shown Mic90 [13].
Тable А5
The MIC90 tetracycline values towards the human bowel microflora.
The proportion in normal
Mic90,
Bacteria type
bowel microflora, %
мcg/ml
Bifidus bacteria spp.
85
32
Bateroides spp.
4.99
32
Clostridia spp.
0.01
32
Lactic bacteria
4
32
Peptostreptococcus
2
32
E. Coli (coliform
1
64
bacterium)
The results of calculations of parameters for every bowel microflora bacteria,
for every age group, by the norms, recommended ТС, WHO (1990), FAO/WHO
(1998) and accepted in the USA are shown in the Tables е А6, А7, А8 and А9.
16
Table А6
Changes in intestinal microflora affected by tetracycline residues according to the standards of the CU
84.58
0.16
84.58
4.96
0.17
4.97
0.16
Clostridia spp.
0.01
0.17
0.01
Lactic bacteria
3.66
0.17
Peptostreptococcus
1.99
E. Coli (coliform bacterium)
Opportunistic pathogenic
microflora
1.00
84.55
Bateroides spp.
3.83
0.16
84.89
4.97
0.16
0.16
0.01
3.68
0.16
0.17
1.99
0.17
1.00
3.78
Share in a
normal flora
of an
intestinal
tract, %
number of tetracycline in a
stomach
0.17
Bifidus bacteria spp.
Bacteria type
Share in a
normal flora
of an
intestinal
tract, %
adults
number of tetracycline in a
stomach
Share in a
normal flora
of an
intestinal
tract, %
Share in a
normal flora
of an
intestinal
tract, %
teenagers
number of tetracycline in a
stomach
Share in a
normal flora
of an
intestinal
tract, %
School aged children
number of tetracycline in a
stomach
children from 3 to 7
years old
number of tetracycline in a
stomach
children until 3 years
old
0.04
84.87
0.05
4.98
0.04
4.98
0.05
0.16
0.01
0.04
0.01
0.05
3.68
0.16
3.92
0.04
3.90
0.05
0.16
1.99
0.16
2.00
0.04
2.00
0.05
0.16
1.00
0.16
1.00
0.04
1.00
0.05
3.78
3.20
3.24
17
Table А7
Changes in intestinal microflora affected by tetracycline residues according to the standards of WHO (1990)
Share in a
normal flora
of an
intestinal
tract, %
80.78
1.59
80.70
1.62
83.75
4.72
1.74
4.74
1.59
4.74
1.62
Clostridia spp.
0.01
1.74
0.01
1.59
0.01
Lactic bacteria
3.78
1.74
3.80
1.59
Peptostreptococcus
1.89
1.74
1.90
E. Coli (coliform bacterium)
Opportunistic pathogenic
microflora
0.97
1.74
0.98
Bifidus bacteria spp.
80.38
Bateroides spp.
Bacteria type
8.25
7.79
Share in a
normal flora
of an
intestinal
tract, %
number of tetracycline in
a stomach
Share in a
normal flora
of an
intestinal
tract, %
Share in a
normal flora
of an
intestinal
tract, %
adults
0.47
83.73
0.48
4.92
0.47
4.92
0.48
1.62
0.01
0.47
0.01
0.48
3.80
1.62
3.94
0.47
3.94
0.48
1.59
1.90
1.62
1.97
0.47
1.97
0.48
1.59
0.97
1.62
0.99
0.47
0.99
0.48
7.89
4.42
number of tetracycline in
a stomach
1.74
teenagers
number of tetracycline in
a stomach
Share in a
normal flora
of an
intestinal
tract, %
School aged children
number of tetracycline in
a stomach
children from 3 to 7
years old
number of tetracycline in
a stomach
children until 3 years
old
4.45
18
Table А8
Changes in intestinal microflora affected by tetracycline residues according to the standards of FAO/WHO (1998) and Codex Alimentarius
Share in a
normal flora
of an
intestinal
tract, %
adults
Share in a
normal flora
of an
intestinal
tract, %
number of tetracycline in
a stomach
Share in a
normal flora
of an
intestinal
tract, %
teenagers
number of tetracycline in
a stomach
Share in a
normal flora
of an
intestinal
tract, %
School aged children
number of tetracycline in
a stomach
Bacteria type
children from 3 to 7
years old
number of tetracycline in
a stomach
Share in a
normal flora
of an
intestinal
tract, %
number of tetracycline in
a stomach
children until 3 years
old
Bifidus bacteria spp.
80.11
1.84
80.48
1.70
80.43
1.72
83.59
0.53
83.59
0.53
Bateroides spp.
4.70
1.84
4.72
1.70
4.72
1.72
4.91
0.53
4.91
0.53
Clostridia spp.
0.01
1.84
0.01
1.70
0.01
1.72
0.01
0.53
0.01
0.53
Lactic bacteria
3.77
1.84
3.79
1.70
3.79
1.72
3.93
0.53
3.93
0.53
Peptostreptococcus
1.89
1.84
1.89
1.70
1.89
1.72
1.97
0.53
1.97
0.53
E. Coli (coliform bacterium)
Opportunistic pathogenic
microflora
0.97
1.84
0.97
1.70
0.97
1.72
0.99
0.53
0.99
0.53
8.55
8.13
8.19
4.60
4.60
19
Table А9
Changes in intestinal microflora affected by tetracycline residues according to the standards adopted in the United States
Bifidus bacteria spp.
64.55
7.7
64.10
7.87
64.33
7.78
79.93
1.91
78.44
2.47
Bateroides spp.
3.79
7.7
3.76
7.87
3.78
7.78
4.69
1.91
4.60
2.47
Clostridia spp.
0.01
7.7
0.01
7.87
0.01
7.78
0.01
1.91
0.01
2.47
Lactic bacteria
3.04
7.7
3.02
7.87
3.03
7.78
3.76
1.91
3.69
2.47
Peptostreptococcus
1.52
7.7
1.51
7.87
1.51
7.78
1.88
1.91
1.85
2.47
E. Coli (coliform bacterium)
Opportunistic pathogenic
microflora
0.88
7.7
0.88
7.87
0.88
7.78
0.97
1.91
0.96
2.47
Bacteria type
26.22
26.73
Share in a
normal flora
of an
intestinal
tract, %
26.46
8.76
number of tetracycline in a
stomach
adults
number of tetracycline in a
stomach
teenagers
number of tetracycline in a
stomach
School aged children
Share in a
normal flora
of an
intestinal
tract, %
Share in a
normal flora
of an
intestinal
tract, %
number of tetracycline in a
stomach
children from 3 to 7
years old
Share in a
normal flora
of an
intestinal
tract, %
Share in a
normal flora
of an
intestinal
tract, %
number of tetracycline in a
stomach
children until 3
years old
10.45
20
These data indicate that the least changes in intestinal microflora are set due to
tetracycline residues identified in food at the level of 10 mkg/kg (0.01 mg/kg).
The greatest changes in species composition of normal microflora that is reduction
of percentage of symbiontic microorganisms and increase of a number of
potentially pathogenic flora, are fixed at acceptable levels of antibiotic residues in
food accepted in the US.
V. ASSESSMENT OF UNCERTAIN RESULTS
The analyses of shown materials mean the following possible uncertainties:
- the absence or lack of the information about possible effects of tetracycline
chronic effects on human organism, especially to the most sensible group of people
(children, pregnant women, people with diseases of gastro-intestinal tract, old
people) uncertainties, related to undergoing the experiments with animals and in
vitro on human;
- the parameters, used for assessment the exposition and risk estimation
(parameters uncertainties, related to food consumption. For instance, due to food
preferences of some group of people, as the main food in the Republic of
Kazakhstan are considered the meat and milk products);
- the gaps in the scientific theory, necessary for prediction on the base of
causal connections (limited amount of researches, by the results of which the
model parameters were estimated, modified factors using or refuse to use them,
using of the generalized, average information for big population and partial
imagination of microflora balance distortion forming regulations and health
problems of citizens of RoK, connected to it. Therewith, the health risks
underevaluating of RoK citizens is possible, which is related to the absence of
knowledge about the by-product usage, especially, liver and nephros of farm
animals).
Generally, the uncertainty of the results of researches is characterized as high.
21
CONCLUSION
The Republic of Kazakhstan considers that the refusal of uncertainty
coefficient 10 at the rating of tetracycline ADI is not sufficiently proved. Taking
into account the aspects of meat and dairy products using in the Republic, the
tetracycline acceptable residual quantities establishment on the level of
100 mcg/l in milk, 100 mcg/kgs in muscular tissues, 10 mcg/kgs in fat tissues, 200
mcg/kgs in eggs, 300 mcg/kgs in liver, 600 mcg/ kgs in
nephros,
can bring to the
additional disease risks of digestive organs, anemia, dermatitis, allergy and
immune deficiency of most sensible group of people (children, pregnant women,
people with diseases of gastro-intestinal tract, old people). Especially, increasing of
dysbiosis proportion and amount of bowel microflora resistant to antibiotic are
made uneasy.
On the base of abovementioned, the Republic of Kazakhstan considers, that the
tetracycline acceptable residual quantities establishment in food on the degree of
10 mcg/kgs (0,01 mg/kgs) is proved and will not bring to increasing the health
risks of citizens.
22
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