7. RESULTS OF SUBSYSTEM 4: HEALTH EFFECTS AND RISKS OF HUMAN DIETARY EXPOSURE TO CONTAMINANTS

7.1 Organization of monitoring activities

This subsystem is composed of four parts and is carried out in twelve cities (Table 3.1). This number of localities was selected as to represent the regions uniformly. The first part of the subsystem is aimed at the notification of food-borne alimentary infections and cases of intoxication. It utilizes the data collected in the epidemiological system EPIDAT and those available in reports of the Public Health Service. The second part is focused on the monitoring of selected pathogenic bacteria occurrence in sampled foodstuffs. The strains of bacteria isolated from foodstuffs undergo further qualitative investigations including that of their resistance to antibiotics. The third part focuses on the monitoring of toxigenic micromycetes (moulds) incidence in sampled foodstuffs. Isolates of micromycetes are identified as to their genus and species, and their toxigenicity (production of aflatoxins and ochratoxins) is studied. As in 2000, the second and third parts was given the form of pilot studies. In the fourth part of the subsystem, the dietary exposure of the population to selected chemical compounds is monitored. Samples of foodstuffs are concentrated at one place where they are culinarily processed and analysed over selected chemicals. All the results serve to estimate the health risks resulting from nutrition of the population.

7.2 Incidence of alimentary infections and intoxications

Since 1993, within the framework of the subsystem there has been carried out an analysis of incidence of alimentary diseases (so-called human diseases, zoonoses, and food poisonings) in twelve selected localities in the Czech Republic. Analysis of their occurrence is focused on important etiological agents (Salmonella spp., Campylobacter spp., Citrobacter freundii, Shigella spp., E. coli, Yersinia enterocolitica, Staphylococcus aureus, Clostridium perfringens, rotaviruses, adenoviruses, and type A hepatitis virus). Epidemiological data obtained (annual incidence rate, distribution of reported cases according to gender, age, season; analysis of epidemic occurrence, etc.) are compared with overall data for the Czech Republic and with those in preceding years. The trends of incidence concerning the most important alimentary infections and poisonings are compared in the twelve districts, as well as in the Czech Republic as a whole.

In the Czech Republic in 2000, 40 189 cases of salmonellosis (391 cases per 100 000 citizens) were reported, which is 4 622 cases fewer than in 1999. This signifies one of the lowest morbidity rates for the period of 1993-2000 (the lowest morbidity rate was found in 1997 - 385 cases per 100 000 citizens) (Fig. 7.1). A marked drop in annual incidence was recorded in České Budějovice, Ostrava, Znojmo, and Brno. In 2000, 26 people died from salmonellosis, namely 8 due to salmonella sepsis, the rest due to acute salmonellosis. In the period of 1993-2000, 22 people died from salmonella sepsis and 191 due to acute salmonellosis, with S. Enteritides (SE) as the major etiological agent being isolated in 96 % of stools investigated. The proportion of S. Typhimurium (STM) made up 2 % in 2000, no difference was found compared with preceding years. Of the regions under follow-up, a higher isolation rate of this serovar was registered in Prague and in Brno throughout the period of 1996-2000. The data processed according to gender, age, and season did not reveal any changes for 2000. The spectrum of foodstuffs under risk that have served as the suspect vehicle (eggs, poultry meat) remained the same in 2000 as in preceding years.

Among alimentary infections, campylobacteriosis is second in frequency, next to salmonellosis, with increasing epidemiological importance. In 2000, 16 858 cases in the Czech Republic were reported (163 cases per 100 000 citizens), which represents about 7015 more infections than last year. Campylobacter morbidity is rising continuously in the Czech Republic (Fig. 7.1). The highest morbidity in 1999 and 2000 as well as the highest mean annual morbidity was found in Brno. Jablonec n/N is still the only locality without a single reported case of campylobacteriosis since 1993. The highest number of reported cases has been registered in subjects under 35 years of age, most in children under 1 year of age. The major etiological agent is Campylobacter jejuni.

The number of reported cases of shigellosis (548, i.e. roughly 5 cases per 100 000 citizens) in 2000 signalises that the trend of continued decrease in annual incidence rate has stopped in the last two years. In 2000, the highest morbidity was recorded in Šumperk (24.3), the lowest in Ústí n/L and H. Králové, namely in regions where the highest mean annual morbidity in 1995-1999 had been reported (40 cases per 100 000 citizens). The proportion of the Roma population in the total morbidity has fallen from 37 % in 1999 to 25 % in 2000. The dominant etiological agent remains Shigella sonnei (77 %). The analysis of reported cases according to age and season does not differ from analyses in preceding years.

The annual incidence of infections caused by E. coli is roughly the same in 2000 as in the previous year, amounting to 1 189 reported cases (12 cases per 100 000 citizens). This is 23 cases more than in 1999. Higher morbidity was found in Ostrava (22 cases per 100 000 citizens) and in Benešov (21 cases per 100 000 citizens). Ostrava has also one of the highest mean morbidity ratio during the period 1993-1999 (28 cases per 100 000 citizens). The highest mean morbidity ratio (33 cases per 100 000 citizens) during that period was found in Brno, however, the annual morbidity registered there in 2000 was lower than national mean. No case was reported from Šumperk and H. Králové. E. coli infections primarily affected children under 4 years of age, fluctuating in occurrence during the whole year. The pattern of identified E. coli serovars has not changed substantially since 1997. In 2000, serovar O157 was isolated 114-times, and that number does not differ markedly from that in previous years.

In 2000, 231 cases of yersinioses (2 cases per 100 000 citizens) were reported in the Czech Republic, which is 20 cases more than in 1999. The highest morbidity was registered in Brno (6 cases per 100 000 citizens). In the period 1993-1999, the highest mean morbidity was registered in Ostrava and Č. Budějovice; in 2000 a three-fold decrease was found there. In the last two years, no cases were reported from Jablonec n/N, Plzeň, and Šumperk. Znojmo and Žďár n/S reported each only one case in 2000. Analysis of morbidity revealed the highest numbers among children under 4 years of age, including children under one year of age. Yersinioses do not pose any serious epidemiological problem in the population of over 15 years of age. The major etiological agent is Yersinia enterocolitica.

In 2000, the reported incidence of alimentary intoxications doubled to 1093 cases (5 cases per 100 000 citizens), which is 569 cases more than in 1999. The annual incidence of food-borne poisonings was reported only by three regions: H. Králové, Prague, and Šumperk. The highest incidence rate was observed in the age group of 15-19 years, in which 354 people fell ill, i.e. 33 % of the total. No case has been reported involving children under 1 year of age. Among the suspect vehicles of intoxication reported in connection with epidemics were e.g. Italian-style spaghetti (418 cases), vegetable salad (102 cases), fruit salad (84 cases), and Bavarian scones (33 cases). The proportion of cases that have not been investigated in the laboratory rose in 2000 to the highest level - 77 %. In question were cases connected epidemiologically where not all cases are investigated in the laboratory. In 2000, 12 epidemic outbreaks in the Czech Republic were reported, 1084 subjects were affected.

In 2000, among reported gastroenteritis cases of viral origin appeared only data on adenovirus (44 cases) and rotavirus infections (833 cases). The incidence of rotavirus infections rose by 214 cases in comparison with 1999. Problems of these infections has been monitored in the half of the regions, among which Plzeň dominated with the highest mean morbidity rate in 1993-1999 (88 cases per 100 000 citizens). Children were affected predominantly, not only those under 4 years of age, but in the age group 5-9 years as well.

In 2000, 614 cases of viral hepatitis - type A (VHA) were reported, that is 325 cases less than in 1999. The declining trend is continuous, with the exception of 1996 when the incidence rate was double in comparison with the preceding year. In 2000, morbidity rate in the Czech Republic (6 cases per 100 000 citizens) was markedly exceeded in the region of Ústí n/L (93 cases per 100 000 citizens) and slightly in Brno (10 cases per 100 000 citizens). In all the other regions, a marked decline in morbidity in comparison with 1999 as well as with the mean morbidity in 1993-1999 was recorded. Analysis of the reported cases in relation to ethnicity revealed a high proportion of Roma being involved (58 % in the Czech Republic as a whole; 75 % in Ústí n/L). Parenteral VHA transmission was reported in a healthcare facility in one case and in six cases off healthcare facilities. The proportion of epidemiologically unresolved cases in the Czech Republic dropped from 50 % in 1999 to 34 % in 2000. As in 1999, in 2000 the most affected groups were children in age groups 1-4 and 5-9 years. In the population over 15 years, a marked decline in all age groups was recorded.

7.3 Bacteriological analysis of foodstuffs

The pilot study was focused on the occurrence monitoring of selected pathogenic agents in foodstuffs bought in the market network. The selection of investigated commodities was made up as to represent the mean consumption of foodstuffs in the Czech Republic. Subsequently, the foodstuffs with the most frequent share in origin of foodborne infections in CZ or in other countries were chosen.

Attention was focused on the demonstration of four etiological agents - the cause of serious alimentary infections: Salmonella spp., Campylobacter spp., Listeria monocytogenes, and E. coli O157. Except for Salmonella spp, the other agents are monitored only exceptionally within the framework of the foodstuffs safety routine public control. Therefore, information on their occurrence in individual commodities in the territory of the Czech Republic is lacking. Microbiological analysis has been carried out following standards and methodological recommendations valid in the Czech Republic. The isolates obtained were confirmed biochemically, and the serotypes of Salmonella spp., L. monocytogenes, and E. coli were also determined. In the isolates of Salmonella spp. and Listeria spp., resistance to antibiotics was examined. At S. Enteritidis (SE) and S. Typhimurium (STM) phage typing was performed.

A total of 384 food samples were examined for presence of Salmonella spp. In question were various kinds of meat and offal, including fish, poultry and oven-ready foods, eggs and meat, delicatessen and confectionery products. Positive findings were demonstrated in 17 samples, namely in poultry, egg content, confectionery products, a carp sample, a white-bread dumpling, and a fish salad. The most frequent isolate of Salmonella spp. was that of serotype S. Enteritidis followed by S. Typhimurium, S. Saintpaul, and S. Agona. 168 samples of various kinds of meat and offal were investigated for the presence of Campylobacter spp. A positive finding of C. jejuni was demonstrated in poultry offal only. 552 samples were investigated for the presence of L. monocytogenes (LM), in question were various kinds of meat and offal; milk, fish and delicatessen products; vegetables; and dried fruit. Positive findings of LM were demonstrated in 16 samples, namely in various kinds of meat including poultry, in frozen vegetables and frozen meat products. Most frequently serotype 1/2 was in question. 276 samples of foodstuffs were investigated for the presence of E. coli O157, namely in various kinds of meat, milk products, spices, and vegetables. No sample had been investigated positive by the presence of this pathogen.

7.4 Mycological analysis of foodstuffs

In continuation of the pilot study 1999, in 2000, the monitoring of toxigenic micromycetes (moulds - producers of aflatoxins and ochratoxin A) incidence in selected commodities of the consumer food basket continued. Specialized mycological investigation was focused on the description and characterization of danger of toxigenic micromycetes occurrence in foodstuffs. According to four time schedules, 25 kinds of foodstuffs at 12 sampling sites in the Czech Republic was sampled, in total 300 particular samples of foodstuffs.

Further frequency data series on the qualitative and quantitative occurrence of toxigenic micromycetes were obtained. In selected foodstuffs, a total micromycetes count (colony forming units per g of foodstuff - CFU/g of foodstuff) has been determined and their mycological profiles have been characterized. The occurrence of toxigenic micromycetes monitored has been characterized further by the index of contamination (Ik), this means by the ratio of the number of potentially toxigenic micromycetes (CFU/g of foodstuff) to the total micromycetes count (CFU/g of foodstuff). The presence of potentially toxigenic micromycetes Aspergillus flavus (the producer of aflatoxins) in 8 of a total number of samples (17 %) was demonstrated. In question were the following kinds of foodstuffs: black pepper, caraway seeds, black tea, and farina flour. Five isolated strains of Aspergillus flavus (63 %) were assumed to be toxigenic. Their toxigenicity was verified on the basis of aflatoxin production by a test culture medium. Furthermore, the presence of toxigenic micromycetes Aspergillus tamarii, producers of aflatoxins, was demonstrated in three (25 %) samples of pepper and in three (25 %) samples of black tea. Four isolated strains of the Aspergillus tamarii (67 %) were assumed to be toxigenic. Their toxigenicity has been verified likewise on the basis of aflatoxin production by a test culture medium. Potentially toxigenic micromycetes of the Aspergillus Niger group, producers of ochratoxin A, were found in 41 of 48 samples (i.e. in 85 %) of the following kinds of foodstuffs: raisins, fruit tea, black tea, and black pepper. Significant was the occurrence of the ochratoxin A in four (33 %) samples of raisins (arithmetical mean 4.5 µg/kg; maximum value 9.3 µg/kg) which was determined on the basis of the Aspergillus Niger group occurrence. Interesting was the finding of Penicillium crustosum (producer of the neurotoxin penitrem A) in three samples (25 %) of walnuts and in one sample (8 %) of black pepper.

7.5 Dietary exposure to chemicals

The major objective of the monitoring program in 2000 was the assessment of the mean exposure to chemical substances (significant contaminants of foodstuffs or nutrients and micronutrients). Their content in foodstuffs may pose a health risk of carcinogenic and non-carcinogenic nature.

In 2000, the following two ways of defining the expected consumption of foodstuffs was used: the actual consumer food basket for the Czech Republic which presents the mean availability of foodstuffs at the level of each household member in the year 1994, 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 2000, in all, 2340 samples of foodstuffs were collected. 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 and then mixed into 108 kinds of composite samples for each of the four regions. In all, 432 composite samples were prepared for analysis of basic chemical substances content. 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 analytical determinations (toxic PCB congeners, dibenzofuranes and dioxins, nitrites, etc.), a different rationally based assortment of foodstuff samples combination was applied. In all, 79 chemical compounds in the food samples had been quantified.

The concentrations of chemical substances found were used for calculating the assessment of the mean population exposure in the Czech Republic in 2000 together with values of foodstuff consumption according to the consumer basket. For the long-term comparison of exposure doses (since 1994), the model of recommended doses of foodstuffs for the Czech Republic was applied. It was formulated for five population groups (children, adult males, adult females, pregnant or breast-feeding females, and subjects over 60 years of age). The model facilitates even a long-term monitoring of concentration changes of chemical substances in foodstuffs.

In 2000, the mean chronic population exposure to the organic compounds monitored (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 (as to non-carcinogenic effect). Population exposure estimated according to the foodstuff consumer basket reached the highest level in PCB. Exposure to the sum of seven PCB indicator congeners reached the value of about 10.4 % of the tolerable daily intake (TDI). The highest number of positive findings by the application of analytical methods with increased sensitivity was observed at PCB congeners 153, 138 and 180 (80, 79 and 65 %, respectively), as well as for congener 52 (75 %). A high number of positive findings was found again at p,p-DDE (85 %) and HCB (83 %), as well as alpha isomer HCH (70 %). However, the exposure doses were very low (less than 1 % of the acceptable daily intake (ADI) for the “sum of DDT”, i.e. p,p´DDT + o,p DDT + p,p´DDT + p,p´DDE; and 2.7 % TDI for HCB). This reflects a persisting real contamination, but at a level of very low concentrations without any substantial significance to consumer health. In 2000, the estimate of exposure to chemical substances with the so-called dioxin effect (TEQ 2, 3, 7, 8 - TCDD for the sum of toxic PCB congeners, dioxins, and dibenzofurans) represented the value of about 3 pg TEQ TCCD/kg b.w./d. This value appears to be more favourable in comparison with 1999. Exposure dose estimated according to the model of recommended doses of foodstuffs reaches the highest value in children 4-6 years of age, e.g. exposure to the sum of seven indicator PCB congeners decreased against 1999, nevertheless it reached 40 % TDI.

The mean chronic population exposure to inorganic substances (nitrates, nitrites, cadmium, lead, mercury, arsenic, copper, zinc, manganese, selenium, magnesium, chromium, nickel, aluminium, iron, and iodine) did not exceed exposure limits for a non-carcinogenic effect. Exposure estimated according to the foodstuff consumer basket has shown an increasing nitrates burden (21 % ADI) and a fluctuating nitrites burden (increase to 32 % ADI). A slightly increase was observed in manganese intake (48 % RfD). Cadmium burden has slightly increased (19 % PTWI) as well as lead burden (15.4 % PTWI). In the course of five years, the exposure to mercury reaches continuously favourable values (1.1 % PTWI). The copper and zinc intakes has a continuous tendency to remain low (3.3 % PMTDI and 15 % PMTDI, respectively). Arsenic exposure dose remains practically the same (3.8 % PTWI). After the three years period, a moderate increase of selenium intake was observed (13 % RfD). The estimated exposure dose of nickel and chromium reaches relatively low values with a tendency to vacillation (9 % RfD and 25 % RfD, respectively). The estimated exposure to aluminium and iron did not show any risk of consumer health impairment (4.5 % PTWI and 19.5 % PMTDI, respectively). The exposure estimated according to the model of recommended foodstuffs doses reaches the highest values for age group of children 4-6 years. Exposure to nitrates reached about 95 % ADI, exposure to nitrites increased to about 130 % ADI, exposure to manganese even up to almost 180 % RfD. These results encourage the profound situation analysis of children as they are the risk group in point of nutrition.

Upon the intake evaluation of some trace elements (zinc, copper, selenium, chromium, nickel, manganese, magnesium, calcium, phosphorus, sodium, potassium, iron), the exposure doses were determined according to the foodstuff consumer basket. Zinc exposure was found to be around 104 % of the recommended population intake; copper exposure was slightly below the normative minimum (82 %). Selenium intake was at the level of the population normative minimum (109 %). The normative minimum for chromium was covered at 138 %. The expected requirement of nickel was covered at 311 %, manganese 134 %, magnesium only 83 %, calcium only 91 %, and phosphorus 162 %. The upper limit for sodium intake reached 73 % (i.e. 125 % of the N.A.S. USA recommendation) and the need of potassium was covered at 83 %. The intake ratio of Ca/P was repeatedly low, on the other hand that of Na/K was relatively high. Iron intake reached again only 71 % of the recommended population level. In case the iodinated salt was used for the culinary food preparation, the recommended iodine intake of iodine for the population was covered at least at 84 %. The lowest values of the trace elements have been attained in the age group of people over 60 years, the structure of food consumption in the range of recommended doses of foodstuffs mostly does not cover the recommended trace elements intake.

A theoretical estimate of the probability of number increase of tumour diseases due to dietary 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 (A + B), HCB, and toxic arsenic) amounted to about 76 additional cases in the Czech Republic in 2000. Traditionally, PCBs (44 cases) and As (17 cases) represented the greatest share in this increase. The estimate for chemicals with a dioxin effect (expressed as the sum of TEQ TCDD for PCBs, dioxins and dibenzofurans) amounted to about 62 cases for the Czech Republic and the year 2000. With the application of the model of recommended foodstuffs doses, the highest exposure doses was found in children of 4-6 years of age. The assessment of the number increase of tumour diseases in this population group made up for 8 cases in the Czech Republic (having about 370 000 children 4-6 years old) and the year 2000.

7.6 Partial conclusions

The analysis results of notified alimentary infections in 2000 do not differ distinctly from those in 1999, with campylobacteriosis just registering an increasing trend.

In 2000, selected foodstuffs were sampled for bacteriological analysis, too. The results serve especially to obtain more detailed information on the causes of foodborne alimentary infections. Samples taken simultaneously for mycological analysis confirm the presumption of the relatively frequent incidence of toxigenic micromycetes (producers of mycotoxins - aflatoxins and ochratoxin A) in foodstuffs.

Results of the exposure monitoring to selected hazardous chemicals from foodstuffs in the Czech Republic confirm marked changes of exposure doses in relation to the change in foodstuff consumption structure. The characterization of the health risk appear to be relatively favourable for the average person in the population. However, the exposure doses assessment with the aid of the model of recommended foodstuffs doses revealed certain health risks, namely for children (e.g. greater exposure doses of PCBs, nitrates, nitrites etc.) and elderly people (risk of insufficient intake of certain trace elements). An assessment of the real exposure doses according to gender and age would bring more profound knowledge about the risk groups in our population.

Table 7.1 Recommended foodstuffs doses (servings number/person/day) for selected population groupsa

Population group

Age
[y]

Body
weight
[kg]

Cereals

Vegetable

Fruit

Milk

Protein
sources

Other
food

Energy
[kJ]b

Children

4–6

15

3

3

2

3

2

*

7 047

Male, adult

18+

70

6

5

4

3

3

*

11 996

Female, adult

18+

58

4

4

3

3

1

*

7 988

Female pregn./nurs.

18+

58

5

4

3

3

2

*

9 787

Seniors

60+

64

3

3

2

2

1

*

5 987

* This means temperance in fat, oils, sugar and sweets consumption: used for calculation were 15 g added fats, 10 g added sugar and 300 ml beverages.

Notes:
a Literature used: see Chapter 14
b Energy value of the model without calculating added fats, sugar, sweets and beverages.
Energy value was computed by the sum of weighted means of energy values for particular foodstuffs groups calculated according to the real food availability ratio in CZ in 1997 (SKP 2000, Ruprich et al., 2000).

Model of recommended foodstuffs doses in CZ used for evaluation of exposure to contaminants

Model of recommended foodstuffs doses

Table 7.2 Exposure assessment to selected inorganic compounds, filling the exposure limits follow to the consumer foodstuff basket, 2000

Compound

Exp. limit filling
[%]

Type of exp. limit

Compound

Exp. limit filling
[%]

Type of exp. limit

Arsenic

  4

PTWI

Copper

  3

PMTDI

Nitrates

21

ADI

Nickel

  9

RfD

Nitrites

32

ADI

Lead

15

PTWI

Aluminum

  5

PTWI

Mercury

  1

PTWI

Chromium

25

RfD

Selenium

13

RfD

Cadmium

19

PTWI

Zinc

15

PMTDI

Manganese

48

RfD

Iron

20

PMTDI

Table 7.3 Exposure assessment to the trace elements follow to the consumer foodstuff basket, 2000

Trace element

Meeting the recomm.
daily intake [%]

Trace element

Meeting the recomm.
daily intake [%]

Potassium

  83

Nickel

311

Phosphorus

162

Selenium

  109*

Magnesium

  83

Sodium

  73

Chromium

  138*

Calcium

  91

Iodine

   84+

Zinc

104

Manganese

134

Iron

  71

Copper

    82*

 

 

* Meeting the normative minimum
+ In case of  iodinated salt usage

Fig. 7.1 Notified cases of salmonellosis and campylobacteriosis, 1993–2000
Fig. 7.2a Exposure to PCB indicator congeners from foodstuffs, 1994–2000, model of recommended foodstuffs doses
Fig. 7.2b Exposure to nitrates from foodstuffs, 1994–2000, model of recommended foodstuffs doses
Fig. 7.2c Exposure to nitrites from foodstuffs, 1994–2000, model of recommended foodstuffs doses

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