11. HEALTH RISKS FROM SOIL POLLUTION IN URBAN AGGLOMERATIONS

11.1 Organization of monitoring activities

Subsystem VIII consists of urban soil monitoring with the objective to assess the degree of health risk following from exposure to toxic substances and microbial agents through ingestion of soil and particulate matter from soil (dust). In view of that the greatest probability of increased exposure to noxious substances from contaminated soil is in the child population, the project is focused on kindergarten playgrounds.

In the years 2001 and 2002 there have been carried out samplings of soil and assessments of its contamination in 99 kindergartens in selected towns and cities, namely in kindergartens of Olomouc, Karviná, Klatovy, Kroměříž, and Hradec Králové. The substances followed up in the upper soil of kindergarten playgrounds were toxic metals and polycyclic aromatic hydrocarbons (PAHs), followed up was also its microbiological contamination.

In the year 2003 there have been carried out repeated samplings and analyses of soil samples for microbiological and parasitological determinations at kindergartens in Hradec Králové (2 kindergartens) Olomouc (2), Karviná (2), and Kroměříž (5 kindergartens for previous presence of indicator bacteria and 3 kindergartens for the occurrence of helminths). Those kindergartens were selected on the basis of microbial and parasite contamination found within the framework of monitoring in previous years.

The methodology of soil sampling in 2003 was the same as in previous years, namely to a depth of 10 cm from five sampling sites (points) in each part of a kindergarten. Upon homogenizing the samples from the sampling sites there has been carried out an analysis of composite samples for selected indicator organisms. In repeated samplings of soil in Hradec Králové, Karviná and Olomouc there have been analyzed composite samples as well as individual point samples. In each of the cities under follow-up there has been investigated with the aid of questionnaires the source and possible mode of contamination not only through microbial and parasitary pollution but also by selected chemical substances. Furthermore, through a questionnaire there have been investigated the effects of the contaminants found on the health of children in kindergartens where there has been repeatedly confirmed microbiological and parasitary contamination, as well as in kindergartens where such contamination has never been found.

11.2 The inorganic and organic contaminant content in soil

From the results of samplings of upper soil in kindergartens obtained in the years 2001–2002 it follows that the most significant inorganic contaminants of the upper soil in playgrounds in the urban environment are cadmium, arsenic, and lead, the concentrations of which exceeded the draft limits set in the supplemented Decree of the Ministry of Health No. 464/2000 Dig. for uncontaminated soil, in all the cities under follow-up. From the point of view of the non-carcinogenic effects of metals, however, there has not been confirmed any increased risk through unintentional ingestion of soil in any of the localities assessed. According to the share of the acceptable intake of metals from soil, in all five of the assessed cities a theoretically highest daily intake has been found in lead and arsenic; however, the possible absorption of soil-bound forms of those elements has not been studied. A relatively higher load of lead has been found in Olomouc and Karviná; that of arsenic in Klatovy, Hradec Králové and Kroměříž. On the basis of calculations of the theoretical increase in the probability of contracting cancer due to exposure to arsenic by unintentional ingestion of soil, there has been found an increased risk in Klatovy.

Numerous exceeding of the draft limits of contaminant content for playgrounds have been found in representatives of PAHs classified as proven or probable carcinogens. In all the cities under follow-up there have been exceeded the draft limits for benzo[a]pyrene – in Kroměříž in 100 % of kindergartens, in Olomouc in 96 %, in Karviná in 90 %, in Klatovy in 80 %, and in Hradec Králové in 48 % of kindergartens under follow-up. A higher theoretical estimate of probability of increased occurrence of tumor diseases in consequence of exposure to carcinogenic PAHs from unintentional soil ingestion has been found in Klatovy, Karviná, and Hradec Králové. Of the representatives of carcinogenic PAHs, in those localities there have been evaluated according to the degree of risk in decreasing order benzo[a]pyrene, dibenzo[a,h]anthracene, and benzo[a]anthracene.

Microbial and parasitary contamination higher than allowed in the Ministry of Health Decree No. 464/2000 Dig. has been found in almost a half of the kindergartens under follow-up. The most frequent contamination was caused by enterococci. Not one case of salmonella pollution has been found.

11.3 Factors followed up in the year 2003

In the upper soil in kindergarten playgrounds there have been studied:

Samples of upper soil were taken and processed according to Standard Operational Procedures elaborated within the framework of an associative study, namely for the taking, storage and transport of samples of soil for microbiological determinations of selected microorganisms and for the parasitological investigation of soil. Samples of soil for microbiological and parasitological analyses were taken in the period of May through November 2003.

The questionnaire for investigating the source of contamination in kindergartens was focused on: the locality of the kindergarten within the urban agglomeration, size of the kindergarten and plot, number of children in the kindergarten, previous contamination, information on any reconstruction or redevelopment of the plot, information on any soil backfills, the source of irrigation water, contamination from the ambient air, and safeguards against entry of any dogs or cats.

The questionnaire for investigating the effects of contamination on the health of children in the kindergartens was filled in from healthcare documentation and by their parents. Followed up were namely acute diarrhoeal and parasitary diseases in the children and long-term complaints among children visiting the kindergarten.

11.4 Indicators of microbial contamination of the soil

In view of the results obtained in the follow-up of microbial contamination over the previous years from composite samples, it seemed appropriate to finish the investigation of contamination on the kindergarten premises by a network of individual samples and at the same time to find any survival and source of contamination through questionnaires. Therefore, in 2002 there have been carried out analyses of upper soil for indicators of microbial pollution in 2 kindergartens in Hradec Králové, 2 in Olomouc, 2 in Karviná, and in 8 kindergartens in Kroměříž. Analyses were made of composite and individual samples. In the kindergartens of Olomouc, Hradec Králové and Karviná there has been found continuing contamination and the influence of random sampling of contamination in the individual sample on the resulting values in a composite sample. In samples of upper soil from the kindergartens in Kroměříž there has been studied the continuing contamination in composite samples. Samples were taken in the period April–November  003. Followed up was the presence of salmonella, yeasts and moulds quantitatively, thermotolerant coliform bacteria, enterococci, and geohelminth ova. The results of soil samplings are presented in Tab. 11.1.

For the determination of contamination, the amount of 102 CFU was considered to be the limit value for thermotolerant coliforms and enterococci, which was adopted from the Ministry of Health Decree No. 464/2000 Dig., supplement No. 8 for the assessment of fecal pollution in playgrounds. Results of this phase of working on the task have confirmed that contamination can last even several years, as an example there can serve a kindergarten in Karviná where geohelminth contamination was consistently found in composite samples over a period of 4 years. In samples of upper soil from kindergartens in Kroměříž there has been confirmed contamination in 2 of 9 kindergartens under follow-up in repeat samplings at an interval of one year. Contamination with indicator bacteria in composite samples from kindergartens in Kroměříž, Olomouc and Hradec Králové has not been confirmed as against Karviná where the composite sample did not meet the limit value for indicator bacteria. It can be stated that results obtained in 2003 correspond with those obtained in previous years when there had been taken composite and individual samples in 10 kindergartens of Olomouc and in 2 kindergartens of Karviná.

In a composite sample there has been confirmed a lasting contamination after a year or two in 7 cases of 11 contaminated localities under study. On evaluation of the results it has been found that the most representative results were obtained by analyses of composite samples taken from the whole surface of the facility.

The source and survival of microbial and parasitary contamination were investigated through questionnaires at all the kindergartens under follow-up. In the follow-up of the possible source of contamination there has in no case been found any connection with backfills with compost, leveling or newly introduced soil or substrate, no connection with the locality of the kindergarten nor with covering the playground with a lawn. It can therefore be presumed that the contamination was caused by feces from free-living animals and birds.

11.5 The health of children in connection with soil contamination

The influence of contamination of the upper soil in playgrounds on the health of children was studied in all the cities, each time in one kindergarten where there has been found contamination with indicator organisms, and in one kindergarten where no contamination had been found. There have been followed up series of at least 68 children and at the most of 80 children in each city. Their health was followed up over 6 months, namely through excerpts from the attending physician’s files, as well as on the basis of information from parents, as given in the questionnaire.

From the values presented in Tab. 11.2 it is apparent that there has been found no difference in the numbers of diseased children from kindergartens with playgrounds contaminated with indicator organisms and from those that were not contaminated. During the follow-up of the health of the children there have been found infections with rotaviruses, parasites and other unspecified diarrhoeal affections; however, from the questionnaire survey it was not possible to find any connection with the contamination of playgrounds at the kindergartens.

11.6 Partial conclusions

There has been confirmed the occurrence of lasting contamination of soil for up to four years, namely in contamination with parasites. Persisting contamination has been confirmed in over 40 % of the kindergartens where there has been found a bacterial or parasitary contamination. In no case has there been found any salmonella in the soil samples. In the study of the influence of individual samples on the composite sample it has been found that analysis of the composite sample ensured the most representative results, that being in line with published results in studies. In no case has there been found any connection between the possible source of contamination and backfills of material such as compost, levelling or newly introduced soil or substrates. In the follow-up of the health of the children there have been found rotavirus and parasitary infections and other unspecified diarrhoeal affections, however in the questionnaire survey no connection could be found with the contamination of playgrounds of the kindergartens. It should be stated that these conclusions can be influenced by the relatively short period of follow-up of morbidity in the children and the given size of the series under study.

Presently, there is only a very small number of reports assessing the effects of soil contamination on child morbidity. Knowledge of such connections is of substantial importance for the assessment of the significance of monitoring biological indicators in soil and sand at child facilities, namely for the assessment of any need of carrying out disinfection or other protective measures.

Tab. 11.1 Indicators of the microbial contamination of soil in kindergartens, individual and mixed samples

City, kindergarten

Number
of indi-
vidual
samples

Number
of mixed samples

Number of component samples

TCB*

Enterococci

Salmonella

Helmints

Individual

Mixed

Individual

Mixed

Individual

Mixed

Individual

Mixed

Olomouc I

23

1

3

0

3

0

0

0

Olomouc II

16

1

0

0

0

0

Karviná I

9

1

6

1

Karviná II

10

1

4

1

2

1

0

0

Hradec Králové I

12

2

0

0

1

0

0

0

0

0

Hradec Králové II

0

2

0

0

0

0

0

0

0

0

Kroměříž I

1

0

0

0

Kroměříž II

1

0

0

0

Kroměříž III

1

0

0

0

Kroměříž IV

1

0

0

0

Kroměříž V

1

0

0

0

Kroměříž VI

1

1

Kroměříž VII

1

1

Kroměříž VIII

1

0

Kroměříž IX

1

0

Note: * thermo tolerant coliform bacteria

Tab. 11.2 Questionnaire survey on children’s health status in connection with microbial contamination of soil in kindergartens

City, kindergarten

Number
of children

Diarrhoeal affection

Parasitic disease

Identified

Not identified

Identified

Not identified

Olomouc – contaminated

39

0

2

1

0

Olomouc – non-contaminated

39

1

8

0

0

Karviná – contaminated

29

0

2

0

0

Karviná – non-contaminated

39

0

1

2

0

Hradec Králové – contaminated

39

2

1

0

0

Hradec Králové – non-contaminated

41

1

1

0

0

Kroměříž – contaminated

40

1

1

0

0

Kroměříž – non-contaminated

40

0

2

0

0


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