Contaminants From Food Chains Biology Essay


In the monitoring period 2010/2011 this subsystem was exceptionally comprised of five parts, not including the central acquisition of food samples. The system for sampling of foodstuffs was wholly modernised to achieve better effectiveness and flexibility. The first part of the project deals with monitoring of selected pathogenic bacteria in the foodstuffs sampled. Isolated bacterial strains are subjected to qualitative study exceeding routine microbiological analyses. The second part of the project includes monitoring the incidence of toxigenic micromycetes (moulds) in the sampled foodstuffs. Isolates are identified by genus and species and their toxigenic properties are studied (production of mycotoxins). The third part of the project is devoted to monitoring the incidence of genetically modified (GM) foodstuffs on the Czech market. This section was included primarily to satisfy public demand and requests for data by the EU and non-governmental organizations, and not because any health risks were expected. The fourth part of the subsystem is the largest and forms the basis of the whole project, dealing with monitoring of dietary exposure of the population to selected chemical substances. It employs the methodological scheme of the so-called total diet study which, unlike regular controls of foodstuffs, includes consumer behaviour and a full spectrum of foodstuffs and as such uniquely enables complete characterization of health risks. The fifth section of the project targeted at evaluation of nutrient intake was separated from the fourth subsection in response to the necessity of ever increasing specialization of methodologies in the service of nutritional epidemiology. It includes a separate method of characterising health risks associated with inadequate nutrient intake.

5.1 System for sampling foodstuffs that represent regular population diet in the CR

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Collection of food samples was carried out in 32 selected locations in the Czech Republic (Tab. 5.1.1) based on population count (Tab. 5. 1. 2) and divided into 4 regions (quadrants). In each location samples are collected in three different shops so as to reflect the relative size of shopping outlets in line with consumer preferences. The number of sampling sites depends on financial/capacitive options in order to tie-in with the previous sampling system and be representative of regions nationwide. Over the two-year monitoring cycle samples were collected from 96 outlets across 32 areas in the CR and over 8 periods of time so as to cover expected seasonal changes in food supply.

Tab. 5.1.1 Sampling localities in the market network 2010/2011

Term I

19.1-2.3 2010

18.1.-1.3. 2011

Term II

23.3.-2.5. 2010

22.3.-3.5. 2011

Term III

25.5.-14.9. 2010


Term IV

5.10.-23.11. 2010

4.10.-22.11. 2011


Kutná Hora ProstÄ›jov

Blansko Pelhřimov








ÄŒeské BudÄ›jovice





Mladá Boleslav






Náměšť n. Osl.



ValaÅ¡ské MeziÅ™íčí





Uherské HradiÅ¡tÄ›

Tab. 5.1.2 Selection of shopping localities and no. of purchases according to size of municipality (EHIS CR, 2009)


% population

No. of outlets

No. of purchases

over 100 000 pop.




50 000 - 99 999 pop.




20 000 - 49 999 pop.




10 000 - 19 999 pop.




5 000 - 9 999 pop.




2 000 - 4 999 pop.




to 1 999 pop.








5.2 Bacteriological analysis of foodstuffs

The study focused on bacteriological analysis of foodstuffs involved monitoring the occurrence of selected pathogens in foods available in the market network. Selection of commodities was based on the food basket and, as in previous years, targeted at those food groups that had in the past participated in the occurrence of alimentary diseases in the Czech Republic or abroad.

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Foods were examined for the presence of four etiological agents causing significant alimentary diseases: Salmonella spp., Campylobacter spp., Listeria monocytogenes and S. aureus. Except for salmonella and L. monocytogenes the other agents are monitored only exceptionally during routine food safety inspections. Information regarding their incidence in respective commodities and detailed phenotype and genotype characteristics are unavailable.

Detection and determination of pathogen counts were carried out using reference cultivation methods (EN ISO). Suspected colonies were confirmed and characterised in detail by pheno- and genotyping. For detection of Salmonella spp., a total of 276 food samples was examined. Samples comprised various types of meat, dairy and fish produce, eggs, dumplings, fruit and vegetables. None of the samples were positive for presence of the target pathogen. For detection of Campylobacter spp., a total of 156 food samples was examined. Samples comprised meat, dairy products (frozen desserts), fruit and vegetables. None of the samples were positive for presence of the target pathogen. For detection of Listeria monocytogenes, a total of 264 food samples were examined, yielding 18 (6.5 %) isolates. L. monocytogenes was detected in ground meat (5/41.7 %), beef (8/33.3 %) and fish (3/12.5 %). In one case the pathogen was present in smoked meat (1/4.2 %) and in a smear taken from apple rinds (1/4.2 %). For detection of Staphylococcus aureus, a total of 276 food samples was examined, yielding 22 (8.0 %) isolates. All examined food samples contained counts of coagulase-positive staphylococci < 50 KTJ/g with the exception of one sample of dumplings with 9.102 KTJ/g. Positive findings of the monitored pathogens in particular food commodities are shown in Fig. 5.1.

5.3 Mycological analysis of foodstuffs

In 2011, the second year of a two-year monitoring period (2010-2011), it was continued as part of the MYKOMON study to monitor the incidence of toxicogenic filamentous microscopic fungi (moulds), producers of aflatoxins and ochratoxin A in selected foodstuffs. Specialised mycological examinations continued to be focused on the above issues, with more detailed mycological monitoring of microscopic fungi Aspergillus belonging to the Nigri group, producers of ochratoxin A.

A total of nine types of consumer foods, comprising 108 food samples, was collected from 12 sampling sites nationwide on two occasions. Frequency data was collected concerning qualitative and quantitative incidence of toxicogenic filamentous microscopic fungi, producers of aflatoxins and ochratoxin A, in foods in the Czech Republic. Total counts of fungal content in selected foods (KTJ/g) were determined along with their mycological profiles and contamination indices (Ik) which represent the ratio of potentially toxicogenic filamentous microscopic fungi to the overall count filamentous microscopic fungi (KTJ/g of foodstuffs).

The presence of aflatoxin-producing Aspergillus flavus was detected in 11 samples (18 %) of cereal baby pudding, fruit tea, black tea, various types of flour. The presence of ochratoxin A-producing Aspergillus from the Nigri group was detected in 30 samples (63 %) of raisins, fruit tea, black tea and cereal baby pudding. The presence of potentially toxicogenic filamentous microscopic fungi Penicillium crustosum (potential producers of the mycotoxin penitrem A) was not detected in walnuts during this monitoring period.

5.4 Incidence of GMO foods in the Czech market network

Monitoring of selected foods on the market to identify products that are genetically modified or derived from genetically modified organisms has continued for the tenth year running. As in previous years, samples of four types of food (soya beans, soya products, cornflour and rice) were collected from 12 distribution sites nationwide, on four occasions. A total of 192 samples (48 from each commodity) were collected. Screening and polymerase chain reaction (PCR) were used for detection and identification of GM foods.

In 2011, qualitative PCR revealed 31 samples of cornflour, 14 samples of rice and 1 sample of soya beans as GM positive. PCR applied to samples of cornflour identified the presence of genetically modified corn line MON810 (1 sample), NK603 (3 samples) and NK603 x MON810 (5 samples). Genetic modification failed to be detected in 22 samples of corn flour. All positive samples were tested for Bt63 modification, with negative results. The specific type of modification present remains undetected. One sample of soya beans contained GM Roundup Ready soya.

Results show (Tab. 5.4.1) that GM foods or foods containing GM corn, rice and soya beans are commonly found on in the market network of the Czech Republic. The numbers of positive findings in the monitored food kinds during the period 2002 - 2011 are shown in Fig. 5.2. During 2011 no new scientific data has been published relating to potential health risks resulting from consumption of GM foods.

Tab. 5.4.1 Results of food sample testing for GMO content, 2011


Sample size

Positive findings (%)

Negative findings (%)

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Soya beans


1 (2,1)

47 (97,9)

Soya products


0 (0,0)

48 (100,0)



14 (29,2)

34 (70,8)



31 (64,6)

17 (35,4)



46 (24,0)

146 (76,0)

5.5 Dietary exposure

The aim of this long-term monitoring programme is a point estimation of both mean and specific population group exposure to selected chemicals (contaminants, nutrients/micro-nutrients) in the Czech Republic; this estimation has been followed up as a chronic exposure trend over a longer period. The data obtained assist the characterization of health risks associated with the usual dietary habits of the Czech population and, if necessary, the probability assessment of chronic exposure doses. Such assessment is carried out in 4 - 6 year intervals, upon amassing a sufficient volume of data. The chemical content of foods may represent risk of oncological or other diseases. In the case of nutrients and micro-nutrients the risk of insufficient intake is likewise an issue.

Collected food samples are gathered at a single facility in the Czech Republic where they are subjected to standard culinary treatment and subsequently analysed for content of selected chemical substances. Since 2004 the monitoring of dietary exposure has been performed in two-year intervals. The sampling system is sufficiently representative for the actual diet of the CR population (selected food types represent over 95 % of the mass of diet composition) but not for comparison of regional differences; such a sampling system is limited by available financial resources.

Estimation of exposure doses during the 2010 - 2011 monitoring period involved use of two values of expected food consumption: 'actual value of consumption' (from the national epidemiological study of individual food consumption [SISPO4], which presents values of mean food intake per person in the CR for 2003/2004) and for evaluation of exposure trends a value derived from the model of recommended food doses (so-called food pyramid).

5.5.1 Selection of samples for analysis

The set of samples collected for chemical analysis comprised 205 separate food types from 32 locations in the CR (see introduction of chapter). The overall number of samples (some types were collected repeatedly and from more than one brand) was 3 696 nationwide over a period of 2 years. For economic reasons the food samples are combined into so-called composite samples according to region (quadrant). Samples representative of each region were subjected to standard culinary treatment and classified into 143 individual types of composite samples for each of the four regions of the Czech Republic. Some samples/composites are prepared repeatedly so that the total number per region is 220 composite samples over the whole monitoring period. A total of 880 composite samples was available for analysis of chemical content over the monitoring period and from the whole of the CR. Certain analytical determination (e.g. nitrites and nitrates) employ different and specific selection or combinations of food samples.

5.5.2 Chemical analyses and computation of exposure doses

A total of 93 individual chemical substances were quantified in the food samples, often forming groups of related substances with similar health effects (for instance, 37 types of fatty acids). Detected concentrations of chemical substances were used to estimate mean exposure doses for the CR population in 2010/2011. For long-term comparison of exposure doses since 1994, a model of recommended food doses for the CR was used. This is calculated for 5 typical population groups (children, men, women, pregnant/lactating women, and the elderly) and allows standardization of results to allow long-term monitoring of trends in concentration changes of chemicals in foodstuffs, independently of fluctuations in food consumption.

5.5.3 Exposure to organic contaminants

Mean chronic population exposure doses to monitored organic substances belonging to the group of so-called persistent organic pollutants proscribed by the Stockholm Convention (polychlorinated biphenyls [PCBs], aldrin, endrin, dieldrin, methoxychlor, endosulfan, heptachlor epoxide, hexachlorobenzene [HCB], alpha-, beta-, delta-, gamma- (lindane) isomer of hexachlorocyclohexane, isomers of DDT, DDD, DDE, alpha-, gamma-, oxy- chlordane, mirex) from foods did not in 2010/2011 exceed values associated with significantly increased probability of health damage (non-carcinogenic). Exposure as estimated by actual consumption of foodstuffs (SISPO4) was highest for PCB. Exposure to the sum of seven indicator congeners of PCB (so-called NDL-PCB) reached a mean value of 2.1 % of the tolerable daily intake (CZ-TDI). This value is slightly lower than in previous years.

A high number of analytical captures has always been observed for DDT metabolite p,p'DDE (56 %). Increased numbers of captures were also recorded for hexachlorobenzene (47 %), delta HCH (39 %) and p,p,'DDT (37 %).The fluctuating amount of captures over the years is associated with low measured concentration values and resultant low exposure doses (for instance, 0.1 % of PTDI for the sum of DDT and 0.9 % of TDI for hexachlorobenzene). Results confirm a prevailing blanket contamination by these persistent organic pollutants, albeit in very low concentrations that do not present significant health risk when they are evaluated as individual chemical substances.

Estimates were not made in 2010/2011 of exposure doses for substances with so-called dioxin effect (toxic equivalent of 2,3,7,8-tetrachlorodibenzodioxin [TEQ 2,3,7,8-TCDD] for the sum of 29 dioxin-like [DL] congeners of PCB, dioxins and dibenzofurans) because of budget cuts.

Exposure doses estimated using the recommended food doses model have highest values for the 4 - 6 years age-group. Exposure to the sum of seven indicator congeners of NDL-PCB was 8.4 % of TDI amongst these children. Exposure doses of polychlorinated biphenyls are lower than in the past (Fig. 5.3).

5.5.4 Exposure to inorganic substances and ions

This section is focussed solely on evaluating toxic doses of inorganic substances and ions and is not concerned with the issue of nutritional adequacy of mineral intake. The mean chronic population exposure dose based on actual food consumption (SISPO4) for nitrates, nitrites cadmium, lead, arsenic, copper, zinc, manganese, selenium, chrome, nickel, aluminium, iron, iodine, tin and molybden did not exceed exposure limits for non-carcinogenic effects. Exposure to nitrates and nitrites was 23 % and 25 % ADI, respectively. Mean manganese intake was 35 % of the reference dose (RfD). Cadmium load was 49 % of the tolerable weekly intake TWI (EU). Although lead load remained at practically the same level as in the previous period, the methodology of toxicological evaluation has changed and has stricter parameters. Detected lead exposure for the average population is 0.18 µg/kg body weight/day. In terms of cardiovascular toxicity comparison with BMDL01 [1] yields MOE [2] = 8.3 which is considered acceptable. For lead nephrotoxicity MOE = 3.5 which is also just acceptable. In terms of developmental neurotoxicity in children, the model for children aged 4 - 6 years shows 0.65 µg/kg body weight/day which yields MOE = 0.77. Negative effects cannot be ruled out and it is currently not possible to estimate the number of affected children. Exposure to methylmercury from fish and seafood was only 2.1 % PTWI and exposure to total mercury from other foods was approximately 0.8 % PTWI. Intake of copper and zinc continues to be at toxicologically low levels of 2.8 % and 15 % PMTDI, respectively. Estimated population exposure to so-called 'toxic arsenic' (estimate of the sum of inorganic As compounds) reached 0.08 µg/kg body weight/day, which compared to the lowest BMDL01 yields MOE = 4.3 - 8.6 for lung cancer. This result is noteworthy, albeit with uncertainty. Selenium reached a value of 14 % RfD as in the previous period. Estimates of exposure doses to nickel (7 %) and chrome (21 %) fluctuate slightly year-on year. Estimates of population aluminium exposure were 21 % PTWI (in children aged 4 - 6 years values exceeded PTWI) and 16 % PMTDI for iron; these figures do not represent a threat to consumer health safety. Mean iodine intake was 13% PMTDI. Tin was detected in only 8 relevant food types (canned meat, canned pate, canned fish, sterilized vegetables, vegetable purees, canned fruit, jams, marmalades, fruit-based baby food) with exposure of only 0.04 % PTWI. Estimated molybdenum exposure was 37 % RfD.

The exposure dose estimated according to models of recommended food doses generally reached highest values in the 4 - 6 years age-group. Estimated exposure to nitrates was approximately 101 % ADI (including load from vegetables); exposure to total manganese was 147 % RfD. The health impact of this result is difficult to interpret because the chemical form of manganese was not determined, but may be preliminarily described as serious. Of continuing interest is the development of selenium exposure according to recommended dose models (Fig. 5.4) because its intake is slightly but constantly on the increase in population groups.

5.6 Evaluation of nutrient intake

In the 2010/2011 period it was decided to focus this project on the methodology of evaluating nutrient intake in children because this is the most discussed issue in all nutrition studies. National Institute of Public Health joined the international EFSA project PANCAKE (Pilot study for the Assessment of Nutrient intake and food Consumption Among Kids in Europe) aimed at the creation of harmonised methodology for collecting data on child food consumption in Europe up to 2020. Part of this project were pilot studies carried out in the CR and Belgium, with the assistance of the Netherlands and Denmark, which verified the viability of proposed procedures and the quality of project requisites. In the CR the pilot study involved a total of 231 subjects who were randomly selected from the central register of residents for Brno-City and Brno-Rural regions, according to specific criteria (gender, age, place of residence). The research targeted the following age-groups: infants (3 - 11 months), toddlers (12 - 35 months), children (3 - 10 years) as well as nursing mothers who participated with their infants. Determination of food consumption took place from January 2011 - July 2011 by way of a three-day record and twice repeated 24h recall combined with a record. New EPIC-Soft software developed by the International Agency for Research into Cancer (IARC) was used for data collection. Collected data were further processed including a basic nutritional assessment aimed particularly at determining the distribution of usual nutrition intake in the monitored population groups. During this period the results for energy, proteins, fats, saccharides, calcium, phosphorous and vitamin C were processed.

The resulting data cannot be considered representative for the CR in view of the small number of respondents. Nonetheless, they provide unique methodological and epidemiological information on nutrition intake in small children which is not currently available in the CR in comparable quality. Results are difficult to interpret for the infants age-group because 64 % of the subjects were fully or partially breast-fed and nutritional intake via human milk was not monitored. Data for this age-group are therefore not presented. During evaluation of usual intake in the child age-group the broad age-range of this age group, 3 - 10 years, should be borne in mind.


The median value of regular energy intake in the infants age-group was 4 725 kJ/d, in the child group 6 837 kJ/d and in the lactating mothers group 8 991 kJ/d. These values correspond to energy requirements for the given age-groups. Comparison was carried out with EU (1993) and DACH (2002) recommendations.

Proteins, fats and saccharides

Nutrient intake was expressed as a ratio of total energy intake. Proteins, fats and saccharides were at ratios of 14 % : 32 % : 54 % in infants and children, and 15 % : 37 % : 48 % in the nursing mothers. All values correlated with recommended values although fat intake was slightly higher in the nursing mothers. For saccharides a higher intake of added sugars against WHO (2003) recommended value (< 10 %) was recorded in all age-groups: 14 % in infants, 17 % in children and 14 % in nursing mothers. Also intake of saturated fatty acids (SFA) was higher than the WHO (2010) recommended values (< 8 % in toddlers and children, < 10 % in nursing mothers) in all age groups: 14 % in infants, 13 % in children, 15 % in nursing mothers.


The median value of regular calcium intake was 774 mg/d in the infants age-group, 768 mg/d in the child age-group and 927 mg/d in the nursing mothers. Comparison with available recommendations (EAR [3] , USA) shows that estimated intake is inadequate in 25 % of the infants and nursing mothers groups and approximately 50 % in the child age-group (Fig. 5.5).


The median value for usual phosphorous intake in the infants age-group was 864 mg/d, in the child age-group 1 132 mg/d and in the lactating mothers 1 559 mg/d. Intake is considered adequate in all monitored age-groups when compared to recommendation (EAR, USA). Current detected values pose no threat from excessive intake, as caused by food additives, which is widely discussed in the case of phosphorous. Estimated population exposure doses are 19 mg/kg body weight/d (1 216 mg/person/d), which according to toxicological parameters is 41 % of the doses 3 000 mg/person/d determined by EFSA (2006) as the so-called UL [4] .

Vitamin C

The median value of usual vitamin C intake in the infants group was 55 mg/d, in the child group 50 mg/d and in the nursing mothers 55 mg/d. Comparison with available recommendations (EAR, USA, Fig. 5.6) shows that up to 90 % of nursing mothers had insufficient vitamin C intake. Intake in the infants and child groups appears adequate (insufficiency prevalence < 5 %). In the case of the child age-group the evaluation is problematic due to the greater age-range against recommended values.