11. HEALTH RISKS FROM CONTAMINATED SOIL IN URBAN AGGLOMERATIONS


11.1 Organization of monitoring activities

The subsystem comprises the monitoring of urban topsoil contamination in order to assess the degree of health risks following from exposure to toxic substances from unintentional soil consumption. In view of that the greatest risk of increased exposure is in the child population of preschool age, the project focused on kindergarten playgrounds.

Over the monitoring period of 2002–2004, samplings in 251 kindergartens of 15 cities have been performed; in 2005 in 78 kindergartens of the cities Příbram (N = 10), Benešov (N = 6), Mělník (N = 6), Žďár nad Sázavou (N = 6) and Ostrava (N = 50). The methodology of soil sampling was the same as in previous years: sampling at 10-cm depth from five sampling points in each kindergarten, that have been selected with regard to being occupied by children most frequently. On homogenization the samples from the sampling points, there was carried out an analysis of composite samples for selected contaminants. Each kindergarten was thus represented by one composite sample.

11.2 Factors under follow-up

The following factors have been followed up in topsoil samples from kindergarten playgrounds:

Samples of surface soil were taken and processed according to Standard Operation Procedures for the sampling, storage and transport of soil, and for the analytical determination of selected metals and polycyclic aromatic hydrocarbons in soil. Soil samples for chemical analysis were taken over the period of May through September, 2005. Element analysis was performed by the method of x-ray fluorescence (RTF), excepting beryllium and mercury that were assessed by atomic absorption spectrometry (AAS). Polycyclic aromatic hydrocarbons were analyzed by high pressure liquid chromatography (HPLC) or by gas chromatography and mass spectroscopy (GC-MS).

11.3 Levels of topsoil contamination

11.3.1 Toxic metals and trace elements

Concentrations of metals monitored in the upper layer of urban soil varied in a wide range of values. Basic statistical parameters of the content of selected metals under monitoring in the kindergarten playgrounds of cities followed up in 2005 are presented in Tables 11.1 and 11.2. Included are also the at present recommended public health limits following the amended Ministry of Health Decree No. 135/2004. A comparison of the metal content in kindergarten topsoil in the hitherto studied cities is presented in Figures 11.1a to 11.1e.

The highest mean concentration of lead in the soil of kindergartens under follow-up has been found in Příbram, as expected, where those figures ranged from 120 to 1,060 mg/kg. In the other cities there were usually found concentrations lower than 100 mg lead per kg dry matter; a few kindergartens exceeded that figure (more markedly in Rokycany where in that same kindergarten there has also been found a higher chromium and copper content), see Fig. 11.1a. A special case is a kindergarten in České Budějovice where there has been repeatedly found a high lead content in the soil, approximately quadruple of the maximum found in the contaminated area of Příbram; in that same kindergarten there was also found a high concentration of mercury.

According to the mean concentration of arsenic in the soil of kindergartens it is possible to classify cities into three groups – the most burdened group belong cities, with 30 to 50 mg/kg, being Příbram, Benešov and Teplice. The medium-burdened group, with a mean concentration of 10 to 25 mg/kg, constitute Strakonice, Plzeň, Rokycany, Ústí nad Labem, Liberec, Klatovy and Jablonec nad Nisou. In Liberec there is one exceptional kindergarten having the third highest arsenic content after the two most contaminated kindergartens in Příbram (Fig. 11.1b). All other cities are in the third group with a mean content of arsenic in the topsoil of up to 10 mg/kg dry matter.

For difficulties encountered with the detection limit of the methods applied, the cadmium content has been processed only for a limited number of cities (Fig. 11.1c). The greatest content was found in the kindergartens of Příbram where the median figure reached 2.7 mg/kg, the most burdened kindergarten there had a cadmium level of 10 mg/kg dry matter. In the other cities the mean concentration was mostly under 1 mg/kg, singularly exceeding that level moderately.

The highest level of chromium in kindergarten soil was found in Benešov (median 181 mg/kg), that being followed by Ústí nad Labem, Teplice and Ostrava. In Teplice there has been found the absolutely maximum single value of chromium (286 mg/kg) in a kindergarten where there was also found the second highest level of vanadium, second to an Ostrava kindergarten. The chromium level in the kindergartens of the other cities was in the range of 10–80 mg/kg except for a kindergarten in Rokycany where that level reached 136 mg/kg (Fig. 11.1d).

The greatest mean value for mercury in topsoil of 0.6 mg/kg was found in the kindergartens of Příbram where it ranged from 0.3 to 1 mg/kg. The second highest mean level was found in Jablonec (0.4 mg/kg). Mean values in the other cities were around 0.2 mg/kg and lower. Increased concentrations of mercury of around 1 mg/kg and more were found in four kindergartens in Ostrava and one kindergarten in Olomouc. A high level of 7 mg/kg dry matter was found in a kindergarten in České Budějovice.

Concentrations of beryllium ranged between the detection limit and the maximum of 4.3 mg/kg found in a kindergarten in Ostrava. Lower concentrations were found in Ústí nad Labem, Liberec and Žďár nad Sázavou.

The vanadium content in kindergarten topsoil ranged from 12.5 to 224 mg/kg. The highest was found in the kindergartens of Ústí nad Labem and Benešov.

11.3.2 Polycyclic aromatic hydrocarbons

Results of determinations of polycyclic aromatic hydrocarbons in topsoil of kindergartens are presented in Tab. 11.2 that includes the basic parameters for polycyclic aromatic hydrocarbons classified by US EPA as being carcinogenic.

The concentrations of benzo[a]pyrene in surface soil samples from kindergartens ranged between values below the detection limit up to the maximum value of 3.5 mg/kg found in a kindergarten in Ostrava. There has also been found the highest mean value of benzo[a]pyrene 0.54 mg/kg. On the other hand, the lowest content was found in the soil of kindergartens in Plzeň. The recommended public health limit for benzo[a]pyrene has been exceeded in the majority of kindergartens, see Fig. 11.2.

In view of the lower health risk posed by benz[a]anthracene (its higher recommended limit concentration in comparison to benzo[a]pyrene) the situation concerning contamination with this PAH representative looks relatively favorable. The content of chrysene found in the soil of kindergartens looks unfavorable in view of the recommended limit that has been set very low. In the other carcinogenic representatives of polyaromatic hydrocarbons there has not been set a public health limit; concentration characteristics are presented in Table 11.2.

The share of carcinogenic PAHs in the toxic equivalent of benzo[a]pyrene (TEQ BaP) is the content of Fig. 11.3. The greatest share has benzo[a]pyrene (62 %), trailing far behind is benz[a,h]anthracene (18 %). The range of concentrations of 16 representatives of PAHs found in the kindergartens of cities under follow-up is depicted in Fig. 11.4. Fluoranthene and pyrene have the greatest share, the least having acenaphthylene, naphthalene and acenaphthene. In each of the cities the relative proportion of PAH representatives differs depending on the sources of those PAHs, namely Ostrava differs from the other cities by having a higher proportion of anthracene and fluorene and a lower one of benzo[g,h,i]perylene.

11.4 Health risks of unintentional soil ingestion

The concentrations of selected PAHs found in the soil of kindergartens within the framework of Subsystem VIII can serve as a basis for evaluation the health risks posed by contaminated soil through unintentional ingestion by the child population of preschool age.

The health relevance of the metal soil contamination can be expressed as the potential share in the overall oral exposure, i.e. by the contribution to dietary exposure. The relation between the estimated exposure and the exposure limit (recommended by the WHO – PTWI, PMTDI, TDI, etc.), or the reference dose RfD (set by US EPA) expresses also the so-called Hazard Index (HI); the exceeding of the value “1” signifies a higher intake of a given substance than is acceptable.

By the health risk assessment there should be keep on record that the exposure factors applied are always biased by a relatively great degree of uncertainty. Among the factors of uncertainty counts the individual amount of soil ingested, varying measure of biological availability of the contaminants etc.

11.5 Partial conclusions

From the results of the monitoring of topsoil in urban agglomerations it is apparent that due to unintentional ingestion of soil, inorganic contaminants important as regards health, can be arsenic and lead. The concentrations exceeded recommended limit values for non-contaminated soil in the majority of kindergartens of all the cities under follow-up. For those metals there have also been determined the theoretically highest daily intakes due to unintentional ingestion of soil by children. A great lead burden has been confirmed in Příbram. A greater arsenic burden has been found in Příbram and Benešov. In Příbram there have also been found high concentrations of cadmium, in Benešov also of chromium and vanadium.

The health risk of exposure to polycyclic aromatic hydrocarbons not classifiable as carcinogenic by US EPA, has been found to be low. As far as carcinogenic PAHs are concerned, the recommended maximum content of benzo[a]pyrene that is considered to be the healthwise most serious representative of PAHs, has been exceeded in the majority of kindergartens. The recommended benzo[a]anthracene content in soil has been exceeded only sporadically.

In the framework of screening topsoil sampled in kindergarten playgrounds, the results of Subsystem VIII could serve for the assessment of the potential risk to the preschool child population, e.g. following the criteria of US EPA methodology. By applying the residential scenario the outputs of the computing model do not reflect the degree of the actual risk for children in kindergartens having their specific exposure scenario. Nevertheless, there shall be focused attention on the sampling sites (kindergartens) having higher contaminant concentrations in the topsoil, and from the point of view of pre-emptive caution the measures shall be recommended there.

Tab. 11.1 Concentration of elements in the topsoil of kindergartens

 

Concentration of elements [mg/kg]

Lead

Arsenic

Cadmium

Chromium

Mercury

Beryllium

Vanadium

Copper

Recommended limits
for non-contaminated soil

50

10.0

0.30

85

0.30

1.50

80.0

45

Příbram N = 10

Median

323.5

45.1

2.74

60.1

0.62

2.00

91.2

40.0

Arithmetic mean

422.1

53.1

3.53

58.2

0.60

2.21

85.6

40.8

Xmax

1,060.0

97.3

9.96

67.6

1.04

3.40

98.0

71.1

Xmin

121.0

18.8

1.12

41.8

0.30

1.40

56.4

22.7

Standard deviation

277.6

24.8

2.51

8.7

0.25

0.64

12.5

15.0

Benešov N = 6

Median

27.7

39.5

0.30

181.0

0.15

2.10

140.5

39.1

Arithmetic mean

40.0

38.4

0.37

165.3

0.14

2.27

131.1

40.5

Xmax

86.0

72.0

0.52

223.0

0.20

3.50

169.0

53.6

Xmin

22.8

16.2

0.30

78.0

0.06

1.60

82.5

28.0

Standard deviation

22.6

17.6

0.10

58.7

0.06

0.64

28.0

7.9

Mělník N = 6

Median

30.6

9.8

0.33

27.2

0.16

22.5

17.2

Arithmetic mean

32.0

8.8

0.36

26.1

0.21

22.1

25.9

Xmax

43.8

11.2

0.51

34.2

0.45

28.6

76.9

Xmin

23.0

5.2

0.30

17.8

0.11

12.5

12.2

Standard deviation

7.9

2.5

0.08

6.6

0.11

4.9

22.9

Žďár nad Sázavou N = 6

Median

33.4

8.6

0.35

55.8

0.10

0.70

62.5

17.2

Arithmetic mean

35.9

7.7

0.35

54.8

0.14

0.70

65.0

19.3

Xmax

53.9

10.4

0.41

69.6

0.26

0.80

108.0

36.8

Xmin

27.7

3.4

0.30

30.1

0.06

0.60

29.6

8.4

Standard deviation

8.5

2.5

0.05

12.4

0.08

0.06

23.5

9.3

Ostrava N = 50

Median

39.4

8.3

0.62

62.0

0.13

1.82

62.0

26.0

Arithmetic mean

48.3

9.7

0.73

69.5

0.24

1.90

72.2

32.6

Xmax

138.0

22.8

1.53

147.0

1.20

4.32

185.0

120.0

Xmin

19.2

4.6

0.30

42.4

0.02

0.77

34.8

12.6

Standard deviation

26.7

3.8

0.30

22.9

0.27

0.71

30.2

20.9

N – number of kindergartens
Xmax – maximum pollutant concentration
Xmin – minimum pollutant concentration

Tab. 11.2 Concentration of selected PAHs in the topsoil of kindergartens

 

Concentration of PAHs [mg/kg]

Benzo[a]-
anthracene

Benzo[b]-
fluoranthene

Benzo[k]-
fluoranthene

Benzo[a]-
pyrene

Indeno-
[1,2,3-c,d]-
pyrene

Di-
benz[a,h]-
anthracene

Chrysene

Recommended limits
for non-contaminated soil

1

L

L

0.1

L

L

0.01

Příbram N = 10

Median

0.367

0.427

0.030

0.220

0.046

0.007

0.445

Arithmetic mean

0.692

0.463

0.151

0.329

0.139

0.011

0.840

Xmax

3.275

1.172

1.172

1.260

0.901

0.059

4.208

Xmin

0.060

0.079

UDL

0.095

UDL

UDL

UDL

Standard deviation

0.896

0.266

0.345

0.327

0.260

0.017

1.205

Benešov N = 6

Median

0.050

0.094

0.056

0.102

0.053

UDL*

0.109

Arithmetic mean

0.071

0.162

0.085

0.155

0.088

 

0.176

Xmax

0.136

0.347

0.175

0.307

0.176

 

0.367

Xmin

0.025

0.076

0.039

0.084

0.041

 

0.073

Standard deviation

0.048

0.108

0.054

0.089

0.057

 

0.114

Mělník N = 6

Median

0.661

0.101

0.050

0.083

0.033

0.011

0.084

Arithmetic mean

0.946

0.115

0.062

0.097

0.038

0.018

0.114

Xmax

2.918

0.251

0.162

0.228

0.063

0.056

0.337

Xmin

0.223

0.037

0.022

UDL

UDL

UDL

0.040

Standard deviation

0.903

0.069

0.046

0.063

0.018

0.017

0.102

Žďár nad Sázavou N = 6

Median

0.205

0.247

0.118

0.200

0.217

0.026

0.154

Arithmetic mean

0.205

0.243

0.112

0.192

0.218

0.042

0.148

Xmax

0.293

0.367

0.164

0.291

0.362

0.121

0.196

Xmin

0.119

0.066

0.061

0.101

0.115

0.014

0.087

Standard deviation

0.066

0.101

0.037

0.067

0.083

0.036

0.039

Ostrava N = 50

Median

0.580

0.574

0.281

0.544

0.490

0.051

0.399

Arithmetic mean

0.774

0.748

0.368

0.690

0.669

0.106

0.682

Xmax

3.490

3.710

1.950

3.510

3.580

0.594

2.820

Xmin

0.012

0.089

0.036

0.063

0.032

0.010

0.059

Standard deviation

0.746

0.705

0.373

0.685

0.680

0.126

0.687

N – number of kindergartens
L – limit is not set
Xmax – maximum pollutant concentration
Xmin – minimum pollutant concentration
UDL* – more than half of samples under detection limit


Fig. 11.1a Topsoil lead concentration in the kindergartens
Fig. 11.1b Topsoil arsenic concentration in the kindergartens
Fig. 11.1c Topsoil cadmium concentration in the kindergartens
Fig. 11.1d Topsoil chromium concentration in the kindergartens
Fig. 11.1e Topsoil mercury concentration in the kindergartens
Fig. 11.2 Topsoil benzo[a]pyrene concentration in the kindergartens
Fig. 11.3 Share of the carcinogenic PAHs in the TEQ BaP based on the median value from 273 localities
Fig. 11.4 Concentration of 16 polyaromatic hydrocarbons in the urban topsoil based on 273 localities

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