7. RESULTS OF SUBSYSTEM 4: HEALTH CONSEQUENCES AND RISKS OF HUMAN DIETARY EXPOSURE TO CHEMICALS

7.1 Organization of the monitoring activities

The subsystem is composed of four parts and is carried out in twelve cities (Tab. 3.1). This number was optimized in order to obtain statistically representative results. The first part of the subsystem is aimed at the notification of foodborne alimentary infections and cases of intoxication. It utilizes the data collected in the epidemiological system EPIDAT and those available in reports of Public Health Service. The second part is focused on the monitoring of the occurrence of selected pathogenic bacteria in sampled foodstuffs and the third part on the monitoring of the incidence of micromycetes (moulds) in sampled foodstuffs. The second and third parts had the form of pilot studies in 1999. In the fourth part the dietary exposure of the population to selected chemical compounds is monitored. Samples of foodstuffs are concentrated at one place where they are culinary processed and analyzed in a standard fashion. Exposure assessment is performed by application of the foodstuff consumer basket and the model of recommended daily doses of foodstuffs, respectively.

7.2 Incidence of alimentary infections and intoxications

The monitoring is being carried out in 12 selected districts (their capital cities are participants of the Monitoring System) of the Czech Republic, in which foodborne infections and poisonings have been followed up for seven years, since 1993. Analysis of their occurrence is focused on important etiological agents (Salmonella spp., Campylobacter spp., Citrobacter freundii, E. coli, Yersinia enterocolitica, Staphylococcus aureus, Clostridium perfringens, rotaviruses, adenoviruses and type A hepatitis virus. Obtained epidemiological data (annual incidence rate, distribution of reported cases according to gender, age, ethnicity, season, analysis of epidemic occurrence, etc.) are compared with overall data for the Czech Republic and with preceding years. In this way the trends of incidence concerning the most important alimentary infections and poisonings are obtained not only in the Czech Republic as a whole but also in the twelve districts under follow-up, representing the nationwide population.

No significant changes in the epidemiological situation concerning salmonellosis have occurred in the Czech Republic in 1999 (Fig. 7.1a). In comparison with the preceding year the annual incidence rate of reported cases of salmonellosis in 1999 decreased by 6 000 and that decrease (without statistical significance) also took place in all of the districts under monitoring. In the Czech Republic in 1999, 44 811 cases of salmonellosis (433 per 100 000 of the population) and 34 cases of salmonella sepsis were reported. 21 persons died of salmonellosis, 4 of whom with diagnosed salmonella sepsis. In all, since 1993 through 1999, in the Czech Republic 173 persons died of acute salmonellosis and 14 persons due to salmonella sepsis. The mean annual salmonellosis morbidity rate in the years 1993 through 1999 in the Czech Republic was 457 cases per 100 000 inhabitants and was exceeded in six of the localities under follow-up. The highest values were attained in the districts Brno - city (612), České Budějovice (604) and in Znojmo (594). The lowest mean morbidity rate was recorded in Jablonec n/N (256). The major etiological agent remains S. Enteritidis (SE). It was isolated in 95 % of stools examined. The proportion of S. Typhimurium (STM) in 1999 did not increase and represents 2.2 % (980 isolated strains). In comparison with data reported in the Europe system ENTER-net (international information system on the incidence of enteric pathogens) the proportion of STM in the Czech Republic is still very low. The greatest numbers of STM strains in 1996 through 1999 were isolated in two localities, in Prague and in Brno - city. The spectrum of foodstuffs under risk sharing in the cause of salmonellosis in 1999 remains similar to that in previous years, with eggs, poultry, delicatessen and confectionery goods in the lead. The Benešov district also having meat products as well. In 1999 the insufficiently heat processed pork meat (grilled piglet) became a new vehicle of salmonellosis. In this way, on the territory of the Czech Republic six epidemics occurred, one of which in the district of Benešov affecting 24 persons, and in all of them the etiological agent being STM.

A change in the incidence rate of reported campylobacteriosis occurred. Following a gradual increase since 1993, in 1999 the increase almost doubled in all age groups, also reflecting improved diagnostics of the agent. Altogether there were reported 9 843 cases (95 per 100 000 inhabitants) in the Czech Republic in 1999. A distinct increase was described in Prague. On the other hand, the district of Jablonec n/N became the only locality which did not report a single case of this infection in 1999 and that has continued ever since the follow-up began, i.e. since 1993. The increase in reported cases of campylobacteriosis in the Czech Republic in1999 covers all age groups. The occurrence of campylobacteriosis has a sporadic character in the Czech Republic as yet. The major etiological agent is C. jejuni which was isolated in 98 % of stool samples investigated. In 1999 one epidemic in spa Luhačovice was reported affecting ten children of from 10 to 16 years of age in the district of Zlín (not among the districts under follow-up).

The declining trend in shigellosis morbidity rate came to an end in 1999. There were registered 519 cases of the disease, that being eight cases more than in 1998. Of the districts under follow-up, a decline in annual morbidity rate was evidenced in Brno - city and Prague, on the other hand, an increase occurred in Ostrava and Plzeň - city. The mean annual morbidity rate in the years 1993 - 1999 (10 per 100 000 inhabitants in the Czech Republic) was the highest in Hradec Králové (40) and Ústí n/L (39), the lowest in Prague (4). The share of the Romany gypsy population in the overall morbidity is on the increase. In 1997 it was 28 % and in 1999 37 %, already. The predominant etiological agent is S. sonnei which was the cause of 78 % of reported cases.

The annual incidence rate of infections caused by E. coli in 1999 was about 12 cases per 100 000 inhabitants (1 212 reported cases) in the Czech Republic, that being the mean annual morbidity rate in the period 1993 - 1999. A higher mean morbidity was registered in Brno - city (33 per 100 000) and Ostrava (28), on the other hand the lowest in Šumperk (0.3). The infection affects namely small children under 4 years of age. The most frequently occurring E. coli serovars in 1999 were O26, O55, O126, and O127. Serovar O157 causing hemorrhagic enteritis or the HUS syndrome was detected in 100 cases in 1999, that being 26 isolations less than in 1998. In the districts under follow-up it was detected twice in Brno - city and twice in Ostrava.

The annual incidence rate of yersiniosis in the Czech Republic in 1999 increased by 52 cases in comparison to the previous year. In 1999 210 cases of yersiniosis (2 cases per 100 000 inhabitants) were registered. The problem of yersiniosis is studied predominantly at the Regional Public Health Center in Ostrava, the district with the greatest mean morbidity rate in the period 1993 - 1999 (12 cases per 100 000 inhabitants). The specific morbidity rate is greatest in children under 4 years of age. The incidence rate is higher in the winter months. The sole etiological agent is Y. enterocolitica.

The reported incidence rate of foodborne poisonings in 1999 was roughly the same as in 1998 (524 cases, i.e. 5 cases per 100 000 inhabitants). The districts Brno - city, Plzeň - city, Ústí n/L and Znojmo did not show these intoxications. In 1999 their greater number was registered in Žďár n/S in analogy of 1998, as well as in Benešov. The age distribution of alimentary intoxications covers all age groups except children under one year of age. Analysis of the etiological agent revealed S. aureus (16 times), Cl. botulinum (5 times), Cl. perfringens type A (once) and B. cereus (once). Five people suffered alimentary botulism, three of whom were from the districts under follow-up. The vehicle was home prepared jellied meat with pickled vegetables from home pig-slaughter meat (twice in Šumperk), jellied fish (twice in Liberec) and smoked sprats (once in Brno). None of those affected died.

The annual incidence rate of intestinal infections caused by viral agents increased markedly in the Czech Republic in 1999. 111 cases of infection caused by adenoviruses were reported, 77 cases by Norwalk viruses, and 619 cases by retroviruses. From the districts under monitoring the problem of adenovirus infections is foremostly studied in Prague, that of rotaviruses in Brno - city, Plzeň - city, Prague and Ostrava. In the Czech Republic an increase in adenovirus infections occurred namely in subjects over 75 years of age, in retrovirus infections it was in all age groups and namely in children under 4 years of age. The seasonal incidence of retrovirus infections was atypical in 1999.

The incidence rate of type A virus hepatitis (VHA) in the Czech Republic in 1999 was similar to that in 1998. There were reported 933 cases (9 per 100 000 inhabitants), that being 29 cases more than in the year 1998 (about 3 % annual increase). The mean annual morbidity rate over 1993 through 1999 was the highest in Ústí n/L (40 cases per 100 000), the lowest in Znojmo and Žďár n/S (2). The number of persons parentally infected outside of healthcare facilities in the Czech Republic in 1999 as compared to 1998 fell by almost half. The proportion of those suffering VHA in the Romany gypsy population markedly increased in 1999 as compared to 1998: from 7 % to 29 % in the Czech Republic, from 1 % to 7 % in Prague and from 10 % to 54 % in Brno - city. The specific morbidity rate in the Czech Republic is traditionally the highest in children of 15 - 19 years of age, but in 1999 a higher specific morbidity rate also occurred in groups of 1 - 4 and 5 - 9 years of age.

7.3 Bacteriological analysis of foodstuffs

In comparison with other European countries the number of alimentary infections reported in the Czech Republic is high. One of the causes of such a situation may also be that the system of reporting these diseases in the Czech Republic differs from the one that is usual in most European countries.

Diseases caused by bacterial agents mostly take the course of sporadic cases. Only a small portion of such affections are reported in connection with epidemics (around 10 %), when there is available concrete information on the vehicle of transmission of infection and approximately in 18 % of epidemics of bacterial origin the vehicle is confirmed also by cultivation of the agent. In sporadic cases the vehicle is presented as suspect (around 30 %) or is not named at all.

Therefore, in 1999, in the pilot study MIKROMON attention was focused on the follow-up of four etiological agents of alimentary infection: Salmonella spp., Campylobacter spp., Listeria monocytogenes and E. coli O157. The selection of commodities investigated was aimed at foodstuffs in the distribution network, under risk from the point of view of epidemiology. Bacteriological investigations were performed according to valid standards (ISO ČSN, E. coli O157 according to the NIPH methodological recommendation). The isolates obtained were confirmed biochemically and serotypes were determined. In salmonella and listeria isolates there was followed up their resistance to antibiotics, and in S. Enteritidis (SE) and S. Typhimurium phage typing was carried out.

A total of 384 food samples were examined for the presence of salmonella. In question were various kinds of meat and offal, including fish, poultry and oven-ready foods, eggs, meat products, delicatessen and confectionery products. Salmonella was most often found in poultry (17 % of 48 samples), eggs (5 % of 60 samples), in samples from other kinds of meat and offal (4 % of 84 samples), white-bread dumplings (8 % of 12 samples). The demonstration of the presence of campylobacter microorganisms was carried out in 168 samples of different kinds of meat and offal, including poultry and fish. Positive findings occurred in poultry and offalls (8 % of 48 samples), pork liver (8 % of 12 samples), ground meat (8 % of 12 samples) and pork meat (3 % of 60 samples). In all cases, the species C. jejuni was in question. Examined were 552 samples for L. monocytogenes (LM), in question were various kinds of meat and offal, milk, meat, fish and delicatessen products, vegetables and dried fruit. Positive findings of LM were demonstrated in beef meat (21 % of 24 samples), pork meat and liver (18 % of 84 samples), deep-frozen vegetables (13 % of 36 samples), poultry (10 % of 48 samples), heat-processed meat products (7 % of 84 samples), milk products (1 % of 120 samples). Demonstration of the presence of E. coli O157 was carried out in 276 samples of foodstuffs, in various kinds of meat, milk products, spices and vegetables. The presence of this pathogenic agent was not confirmed in any samples.

7.4 Mycological analysis of foodstuffs

In 1999, in the pilot study MYKOMON, with specialized mycological investigations there were followed up toxigenic mycromycetes (moulds), producers of aflatoxins and ochratoxin, in selected commodities of the consumer food basket, where reliable descriptive data on their occurrence were lacking. 300 samples of foodstuffs from 25 types of commodities in 12 cities of the Czech Republic were taken.

Basic information on the frequency of the qualitative and quantitative occurrence of toxigenic micromycetes was obtained. In selected foodstuffs there were determined total micromycete counts (KTJ/g foodstuffs) and their mycological profile was characterized. There were demonstrated the presence of potentially toxigenic micromycetes Aspergillus flavus (producer of aflatoxins) in 28 % of samples of the following foodstuffs: black pepper, carraway seed, fruit tea, black tea, rolled oats, farina flour and semolina. 75 % of the Aspergillus flavus strains isolated were toxigenic. Aspergillus tamarii (producer of aflatoxins) was found in 35 % of black pepper samples. All the strains isolated were toxigenic. Aspergillus niger, a potential producer of ochratoxin A, was determined in 72 % of samples of the following foodstuffs: raisins, fruit tea, black tea, black pepper, and sweet paprika. Ochratoxin A was detected in raisins. Significant is the finding of Penicillium crustaceum (producer of the neurotoxin penitrem A) in 42 % of walnut samples.

7.5 Dietary exposure of humans

The major objective of the monitoring program in 1999 was again the assessment of the mean value of exposure to chemical substances (important contaminants of foodstuffs or nutrients and micronutrients). Their content in foodstuffs may pose a health risk of tumor and non-tumor diseases.

In 1999, the following two ways of defining the expected consumption of foodstuffs were used: the actual consumer food basket for the Czech Republic and the model of recommended foodstuffs doses. The set of samples supplied for analysis was made up of 195 individual kinds of foodstuffs that had been brought in from four regions of the country, into which the 12 cities under monitoring are arranged (region A = Plzeň, České Budějovice, Benešov; region B = Ústí n/L, Jablonec n/N, Prague; region C = Hradec Králové, Šumperk, Ostrava; region D = Žďár n/S, Brno, Znojmo). In all, in 1999 there were collected in the whole country 2 340 samples of foodstuffs. For economic reasons the foodstuff samples were combined into so-called composite samples according to regions. The combined samples representing each region were culinarily treated in a standard fashion and then mixed into 108 kinds of composite samples for each of the four regions in the country. In all, 432 composite samples were prepared for analysis of the content of basic chemical substances. For the determination of certain chemical substances the composite samples from individual regions were mixed further so that the country is represented by a set of 108 mixed composite samples. For some special analytic determinations (toxic PCB congeners, nitrites, etc.) there was applied a different rationally based assortment or combination of foodstuff samples. In all, 67 chemical substances in the food samples have been quantified.

The concentrations of chemical substances found were used for calculating the assessment of the mean exposure for the population of the Czech Republic in 1999 together with values of foodstuff consumption according to the consumer basket (Fig. 7.2). The applied consumer foodstuff basket describes the mean availability of foods at the level of a family member for the country and year 1994. For evaluating the exposure for the period of run of the Monitoring System (1994 - 1999) there was applied the model of recommended doses of foodstuffs for the Czech Republic (Tab. 7.1), which was formulated for five different population groups (children, adult males, adult females, pregnant or breast-feeding females and subjects over 60 years of age) and which facilitates even a long-term follow-up of changes in the levels of chemical substances in foodstuffs in the course of time.

In 1999, the mean chronic exposure of the population to the organic substances under monitoring (polychlorinated biphenyls (PCBs), aldrin, endrin, dieldrin, methoxychlorine, endosulphane, heptachloroepoxide, hexachlorobenzene (HCB), alpha-, beta-, delta-, gamma- (lindane) isomers of hexachlorocyclohexane, isomers of DDT, DDD, DDE) from foodstuffs did not reach critical values which are connected with an unacceptable increase in the probability of damage to the consumer’s health (in their non-carcinogenic effect). Exposure of the population estimated according to the foodstuff consumer basket reached the highest level in PCBs. Exposure to the sum of seven indicator PCB congeners reached the value of about 15 % of the tolerable daily intake (TDI). Interesting is the repeated increase in exposure to heptachloroepoxide (sum of heptachloroepoxide A + B) that reached the value of over 15 % RfD (reference dose according to US EPA) and the number of positive findings at the 40 % level. The highest number of positive findings was in the application of analytical methods with increased sensitivity as regards PCB congeners 153, 138 and 180 (60, 55 and 50 %, respectively). A high number of positive findings was again found in p,p- DDE (66 %) and HCB (40 %). However, the exposures were very low, less than 1 % of the acceptable daily intake (ADI) for the sum of DDT, i.e. DDT + DDD + DDE, and 2.7 % TDI for HCB. This points to a persisting indiscriminate contamination, but at a level of very low concentrations.

Exposure to PCBs estimated according to the model of recommended doses of foodstuffs (Fig. 7.3a) reaches the highest values in children of 4 - 6 years of age. Exposure to the sum of seven indicator PCB congeners reached the value of 55 % TDI in the year 1999.

The mean chronic exposure to inorganic substances (nitrates, nitrites, cadmium, lead, mercury, arsenic, copper, zinc, manganese, selenium, magnesium, chromium, nickel, aluminum, iron and iodine) did not exceed exposure limits for a non-carcinogenic effect. Exposure estimated according to the foodstuff consumer basket (in summary in Tab. 7.2) reveals a persisting nitrates and nitrites burden (18 and 17 % ADI, respectively). On a long-term basis the intake of manganese, mercury, copper, zinc, arsenic, nickel and chromium is stable. The cadmium burden fell to 17 % PTWI (provisionally tolerable weekly intake), just as the lead burden to 9 % PTWI and no increase in the intake of selenium is observed any more (12 % RfD) Likewise, estimates for aluminum and iron did not present any risk of damage to health in consumers (4 % PTWI and 20 % PMTDI, respectively).

Exposure estimated according to the model of recommended doses of foodstuffs reached the highest values in the category of children of 4 - 6 years of age, and the lowest values in subjects over 60 years of age. Exposure to nitrates (Fig. 7.3b) reached 85 % ADI, exposure to nitrites 60 % ADI (Fig. 7.3c) and exposure to manganese even 174 % RfD. A review of meeting the exposure limits in selected important toxic substances of organic and inorganic origin is presented in Fig. 7.3d and 7.3e regarding the already mentioned age groups of children and adults.

In the evaluation of the intake of certain trace elements (zinc, copper, selenium, chromium, nickel, manganese, magnesium, calcium, phosphorus, sodium, potassium, iron), exposure was determined which for zinc vacillated around 106 % of the recommended population intake. In copper they were moderately below the normative minimum (84 %). Selenium intake was almost at the level of the normative minimum (94 %) for the population. The estimate of the normative minimum for chromium was covered at the 96 % level. The contemplated requirement for nickel was covered 305 %, that of manganese 81 - 162 %, magnesium only 67 - 101 %, calcium 85 % and phosphorus 150 %. The upper limit for sodium intake reached 70 % and the requirement for potassium was covered at 85 %. The intake ratio of Ca/P was repeatedly relatively low, on the other hand that of Na/K was relatively high. Iron intake reached only 71 % of the recommended level for our population. In the case of the use of iodized salt for culinary preparation of food the recommended intake of iodine for the population is covered 115 %. Information on the meeting of recommended daily intakes according to the model recommended doses are presented in Tab. 7.3. The lowest values are attained in the age group of subjects over 60 years of age. The structure of food consumption in the range of recommended doses of foodstuffs mostly does not cover the recommended intake of minerals.

A theoretical estimate of the probability of an increase in the numbers of tumor affections in our population due to exposure (mean of exposure doses according to the consumer food basket) to selected chemicals (sum of 7 indicator PCB congeners, alpha- and beta- isomers of HCH, lindane, p,p- isomers of DDT, DDD and DDE, aldrin, dieldrin, heptachloroepoxide, HCB and arsenic) made up about 91 additional cases in the Czech Republic in 1999. Traditionally it was PCBs, As and HCB that represented the greatest share in the increase of this risk. In the application of the model of recommended doses of foodstuffs the highest values of exposure were reached in children of 4 - 6 years of age. The assessment of the increase in the number of cases of tumor diseases in this population group makes up for 13 cases in the Czech Republic (having about 370 000 children 4 - 6 years old) and the year 1999.

7.6 Partial conclusions

Results of the analysis of notified alimentary infections in 1999 do not differ distinctly from those of 1998, only in campylobacteriosis there is registered a persistently rising trend. In view of the great numbers of this affection it remains a priority in the preventive education of all levels of the population.

In 1999, within the framework of pilot studies, samples of selected foodstuffs for bacteriological and mycological analysis were collected. The results serve foremostly to obtain more detailed information on the causes of alimentary affections of infectious origin and on the contamination of foodstuffs with micromycetes (moulds). A detailed evaluation shall be carried out upon a several-year follow-up.

Results of the monitoring of exposure to selected dangerous chemical substances from foodstuffs in the Czech Republic confirm the presumption of marked changes in exposure in connection with the change in consumption and especially structure of foodstuffs. Assessment with the aid of the model of recommended doses of foodstuffs revealed relative risks for children (e.g. greater exposure to PCBs, nitrates, etc.) and elderly subjects (risk of insufficient intake of certain minerals).

Tab. 7.1 Recommended foodstuffs doses (helping numbers/person/d) for selected population groups

Population group

Age [y]

Body
weight
[kg]

Vegetable

Fruit

Milk

Protein
sources

Energy
[kJ]

Children

4 - 6

15

3

2

3

2

7 047

Male adult

> 18

70

5

4

3

3

11 996

Female adult

> 18

58

4

3

3

1

7 988

Female pregnant/nursing

> 18

58

4

3

3

2

9 787

Older persons

> 60

64

3

2

2

1

5 987

Energetic value of model doesn’t calculate fats, sugar, sweets and beverages added.
Sources used: Brázdová 1995, Brázdová et al. in press, Komárek et al. 1998 and Directive No. 293/97 Sb.

Model of recommended doses of foodstuffs for CZ used for exposure evaluation to chemicals for selected population groups

Model of recommended doses of foodstuffs

Tab. 7.2 Exposure assessment to selected inorganic compounds, computation of exposure limit filling follow to consumer basket of foodstuffs, 1999

Element
Compound

Exp. limit
filling [%]

Kind of exp.
limit

Element
Compound

Exp. limit
filling [%]

Kind of exp.
limit

Arsenic

4

PTWI

Copper

4

PMTDI

Nitrates

18

ADI

Nickel

9

RfD

Nitrites

17

ADI

Lead

9

PTWI

Aluminum

4

PMTDI

Mercury

1.5

PTWI

Chromium

18

RfD

Selenium

12

RfD

Cadmium

17

PTWI

Zinc

17

PMTDI

Manganese

46

RfD

Iron

20

PMTDI

Tab. 7.3 Assessment of daily recommended doses (DDD) of trace elements, computation follow to model of recommended foodstuffs doses, 1999

Element

Derived DDD
[µg/kg b.w./d]

DDD filling
[%]

Element

Derived DDD
[µg/kg b.w./d]

DDD filling
[%]

Potassium

48 000

73

Nickel

0.6

227

Phosphorus

12 500

123

Selenium

6

54

Magnesium

5000

67

Sodium

37 500

87

Chromium

6

61

Calcium

12 500

78

Iodine

2.34

87

Zinc

145

76

Manganese

58

97

Iron

220

49

Copper

21

68

 

 

 

Sources used: Garrow and James 1993, Greeley 1997, Stratil 1993 and WHO 1996.

Fig. 7.1a Notified cases of salmonellosis, 1993 - 1999
Fig. 7.1b Notified cases on campylobacteriosis, 1993 - 1999
Fig. 7.2 Consumption of main kinds of foodstuffs actual shopping in 1991 and 1994
Fig. 7.3a Model exposure to PCB indicator congeners from foodstuffs ingestion, 1994 - 1999
Fig. 7.3b Model exposure to nitrates from foodstuffs ingestion, 1994 - 1999
Fig. 7.3c Model exposure to nitrites from foodstuffs ingestion, 1994 - 1999
Fig. 7.3d Model exposure to selected contaminants from foodstuffs ingestion, children 4 - 6 years, 1994 - 1999
Fig. 7.3e Model exposure to selected contaminats from foodstuffs ingestion, persons over 60 years, 1994 - 1999

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