11. RESULTS OF SUBSYSTEM 8: HEALTH RISKS FROM URBAN SOIL POLLUTION |
11.1 Project objectives
In consequence of the environmental load contaminated soil in agglomerations can contribute to the increased exposure of the urban population to toxic substances and microorganisms through ingestion and inhalation of dust; namely in small children the involuntary (in cases of geophagy, also intentional) ingestion of soil takes place on children’s sporting grounds and playgrounds. Results in published studies confirmed the increased exposure of the population to noxious substances through soil and dust ingestion in localities with contaminated soil.
Since 2000, the monitoring of urban soil has been included in the Monitoring System. The objective is to assess the degree of health risk following from exposure to toxic substances and microbial agents through ingestion of soil and 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.
11.2 Organization and methods
In 2000, a follow-up in ten kindergartens in Karviná and ten Olomouc was carried out within the framework of an association project study. The pilot study of the project took place in 2001, the sampling and analyses of the upper soil were implemented in another 37 kindergartens in Olomouc and in 15 kindergartens in Karviná. Thereby all the kindergartens in the cadasters of both cities were covered. Especially Olomouc had been affected by floods in 1997, however from the results obtained no correlation between inundation and the magnitude of contamination in the soil was found.
The methodology of soil sampling was the same in both years, namely to the depth of 10 cm from five sampling points in each part of the kindergarten that had been selected, the most frequent places were taken into account (except for sand pits). Upon homogenization of the samples from sampling points an analysis of compiled samples for selected noxae was performed.
The following factors were monitored in the upper soil of kindergarten playgrounds:
The upper soil was sampled and processed according to Standard Operational Procedures elaborated within the framework of an associative study, namely for sample taking, storage and transport, for the analytical determination of selected metals and organic substances in soil, for microbiological determinations of selected microorganisms and for the parasitological investigation of soil. Soil samples for chemical, microbiological and parasitological analyses were taken in the period of May – September 2001. Elemental analyses were carried out by x-ray fluorescence (RTF) except for beryllium and mercury which were assessed by atomic absorption spectrometry (AAS). Polyaromatic hydrocarbons were analyzed by high-pressure liquid chromatography (HPLC).
11.3 Levels of upper soil contamination
11.3.1 Toxic metals and trace elements
The concentrations of metals in surface soil layers in kindergartens vacillated in a wide range of values. Results are presented in Table 11.1.
In the kindergartens of Karviná there was found a moderately higher contamination with arsenic, and a markedly higher one with cadmium and beryllium than in those in Olomouc. Analogously, the upper soil in the kindergartens of both cities is contaminated with lead, probably due to the same source – automobile traffic. As regards the other elements, their content in upper soil in both cities is likewise comparable, most probably representing the usual burden in the urban environment.
Excess of the concentration limits proposed for non-contaminated soils was most often found in arsenic, cadmium and lead; in Karviná also as regards beryllium. The most marked exceeding of the proposed concentration limits was found in arsenic and cadmium; in Karviná the median concentration of cadmium reaches almost twice the proposed limit, in Olomouc the median values is only a little lower. The concentration limit for arsenic were exceeded in almost all of the kindergartens. In lead there was not found such significant transgression of the proposed limit; the mean values from all the kindergartens oscillate around the limit value. In Karviná 36 % of kindergartens were with an above-limit finding, in Olomouc it was 42 %.
In mercury and vanadium the values of exceeding the proposed limit values for non-contaminated soil were negligible, the exceeding of recommended maximum concentration of copper is not significant, in chromium it was not found in any of the kindergartens.
The health relevance of contamination of the upper soil with metals can be expressed as the potential share in the overall oral exposure by soil and soil dust ingestion, i.e. as a contribution to dietary exposure. The tolerable weekly lead intake (PTWI) as recommended by the WHO is 25 µg/kg b.w./wk. For a 15-kg child this exposure limit represents a maximum of approximately 53.6 µg/day. It is very difficult to determine the actual consumption of soil in small children; therefore, for an estimate of potential exposure the exposure factors elaborated by the US EPA (1998) were applied: unintentional consumption of soil and soil dust 200 mg per day with a frequency of exposure amounting to 210 days in a year for a 15-kg child.
Using the average value of soil lead contamination in kindergartens, the exposure of children in Olomouc may amount to 9 µg/day, i.e. 17 % of the exposure limit PTWI; in Karviná that being 7 µg/day or 14 % PTWI. In the most unfavourable case of the most contaminated kindergarten, exposure to lead from the soil could amount to 19 µg/day, i.e. 36 % of the exposure limit. When applying in the published sources the upper end of interval on the ingestion of soil being 800 mg/day, in the most contaminated kindergarten the exposure limit could be exceeded. For sake of comparison, it can be stated that according to data from the Monitoring System, the average adult in the Czech Republic has a daily intake of lead from foodstuffs equalling 35 µg/day, that representing about 15 % of the exposure limit. Moreover, in contrary to adults, in small children various negative factors are in play, such as a relatively high intake of foodstuffs and therefore also of contaminants per unit of body mass, higher absorption of lead from the gastrointestinal tract (25–50 % compared with 10 % in adults), etc.
The limit exposure value for cadmium (PTWI) was recommended by the WHO to be 7 µg/kg b.w./wk, i.e. for a child weighing 15 kg, equalling 15 µg/day. The US EPA reference value is identical (RfD 1 µg/kg b.w./day). Applying the same exposure factors as in the case of lead, the potential contribution through ingestion of soil in a Olomouc kindergarten with average contamination, to the overall oral exposure would be 0.056 µg of cadmium/day (0.4 % of the exposure limit), in Karviná 0.1 µg/day (0.7 % of the exposure limit). In the case of the most contaminated kindergarten, the intake of cadmium may amount to 1.4 % of the exposure limit, applying the upper end of the ingestion interval 800 mg/day, up to 5.5 % of the exposure limit. For comparison, the average adult in the Czech Republic has an intake of cadmium through foodstuffs in the amount of 19 % of the exposure limit.
For arsenic or its inorganic (toxic) form there has been recommended a maximum intake PTWI of 15 µg/kg b.w./wk (thus, for children weighing 15 kg, approximately 32 µg/day). The US EPA determined a more strict exposure limit RfD of 0.3 µg/kg b.w./day. Applying the same exposure factors as in the case of lead and cadmium, the contribution of arsenic from soil ingestion in Olomouc average contaminated kindergarten is 1.6 µg/day (5 % PTWI), in Karviná 1.7 µg/day (5.4 % PTWI). In the most contaminated kindergarten the intake can reach almost 8 % of the exposure limit, and applying the upper end of the consumption interval of 800 mg/day, up to 31 %. For comparison, the average adult in the Czech Republic has a toxic arsenic intake from foodstuffs in the amount of 4 % PTWI (27 % RfD). Arsenic ingested in the diet, together with PCBs, has the greatest share in the carcinogenic risk from foodstuffs. Namely arsenic is classified by the US EPA, as well as by IARC, as a proven carcinogen for humans, i.e. in that sense a substance with a non-threshold effect. Therefore, with the knowledge of the carcinogenic potential of arsenic, it is necessary to assess the importance to health of the arsenic levels in the upper soil also with the aid of a theoretical estimate of the increase in probability of contracting cancer in consequence of unintentional ingestion of soil. Applying the above-mentioned exposure factors and the contemplated exposure duration of 3 years, such an estimate does not represent an increase in the probability of contracting cancer due to soil ingestion even in the most contaminated kindergartens. In cases of a greater daily ingestion of soil at the upper end of the interval published, however, an increase in the risk could occur.
11.3.2 Polycyclic aromatic hydrocarbons (PAHs)
Urban areas generally represent localities with the highest PAH content in the soil due to the concentration of their major sources – industry, furnaces, and automobile traffic. The magnitude of the PAH content in soil, in literature, is presented in from tens to hundreds of mg per kilogram of dry matter. The highest levels are reported to the depth of 30 cm, further on they diminish. The half-lives of PAH degradation range from two months (naphthalene) to two years (di-benz[a,h]anthracene). PAH levels in the soil depend on the organic matter content which they are bound to. The maximum levels are therefore found in chernozem, rich in humus, little in sandy soils.
The levels of individual PAHs in the soil of playgrounds in kindergartens were found in a wide range of values, from below the detection limit, up to 20 mg per kg dry matter. The overall content of PAHs under follow-up in both cities differed to the detriment of Olomouc where the mean concentration of PAHs was 15.3 mg/kg dry matter, half of the kindergartens having a PAH content amounting to up to 5.6 mg/kg (median of the values found). In Karviná the mean concentration was 6.2 mg/kg, in half of the kindergartens the content reached up to 3.8 mg/kg. The proposed concentration limit of 1 mg PAH/kg of soil was met by samples from three kindergartens in Olomouc, by none in Karviná.
In the group of polycyclic aromatic hydrocarbons not classifiable by the US EPA as carcinogenic, there were found only singular exceedings of the proposed maximum levels (Table 11.2). In certain PAHs the content in the soil of over half of the kindergartens was below the detection limit of the analytical methods applied.
On the other hand, in the group of PAHs classified by the US EPA as proven or probable human carcinogens, were found many exceedings of the proposed limits for contaminant levels in playgrounds (Table 11.3). In the kindergartens of Olomouc, surprisingly, there were found higher levels of carcinogenic PAHs than in the kindergartens of Karviná, namely as to the magnitude as well as frequency of the exceedings. The concentrations of carcinogenic PAHs in Olomouc were higher, not only in the mean values of all its representatives, but also in the median values as well. Enhanced concentrations are serious namely in benzo[a]pyrene which is considered to be the most serious PAH from the health point of view, and is also the best studied representative of PAHs from the point of view of effects on the human organism. Benzo[a]pyrene contamination levels of kindergarten playgrounds in Olomouc and Karviná varied from tenths of a mg/kg to almost two tens of mg/kg in the most polluted kindergarten. The proposed value of maximum content for non-contaminated soils (0.1 mg/kg) was met by five samples out of a total of 72 kindergartens. The theoretical estimate of increased probability of contracting cancer by benzo[a]pyrene also signalizes the potential increased risk under regular ingestion of soil, namely in the most burdened playgrounds.
11.3.3 Indicators of microbial contamination
The limit values of fecal microbial and parasitological pollution indicators were exceeded in 40 % of the kindergartens under follow-up; in 18 % of kindergartens as regards thermotolerant coliform bacteria, and in 26 % of them as regards enterococci. All the samples were negative for salmonellae (Table 11.4., Fig. 11.1a, Fig. 11.1b). Findings of moulds and yeast all exceeded the limit; in 3 % of kindergartens in the range of 103–104 CFU, in 69 % of them in the range of 104–105 CFU, and in 28 % of them it was over 105 CFU (Table 11.4, Fig. 11.1c). Contamination with geohelminths was recorded in 50 % of kindergartens under follow-up. Of those, 17% of findings were pathogenic or facultatively pathogenic for humans.
Within the framework of an associative study the occurrence of microbiological indicators of pollution in relation to the sampling depth was verified in two localities in Prague (a public and a kindergarten playground). The soil was sampled at depths of 0–5 cm, 5–10 cm, 10–20 cm, total four times in the period of April – October 2001. The quantity of thermotolerant coliform bacteria, enterococci, yeast and moulds was studied, as well as the presence of salmonellae and geohelminth ova. The findings expressed in the median values of four determinations of microbiological contamination in relation to depth of sampling are presented in Table 11.5.
The highest numbers of microorganisms demonstrable, however, only in yeast and moulds, were found in the surface soil layer of from 0 to 10 cm. With the depth of sampling the numbers of microorganisms found decrease. Contamination with thermotolerant coliform bacteria was found in only two cases, enterococci in one. The presence of salmonellae was not demonstrated in any case. On the basis of results of the this study and of other documentation (NIPH and KHS Ostrava) the methodology of the soil sampling has been revised and amended for the next stage of monitoring within Subsystem 8.
11.4 Partial conclusions
In the playgrounds of kindergartens in both cities under follow-up, the exceeding of the limit concentrations proposed for non-contaminated soils was found most often in arsenic (limit values exceeded in almost all the kindergartens), in cadmium and lead, in Karviná also in beryllium. The most marked exceeding of the proposed maximum levels was found in arsenic and cadmium. In mercury and vanadium the values of exceeded proposed limit values for non-contaminated soil were sporadic and moderate, the exceeding of recommended maximum levels of copper does not pose any hazard to health at the levels detected; in chromium it was not exceeded in any of the kindergartens.
From the point of view of the drawing of exposure limits by soil ingestion, a higher level was found in lead. At the average value of soil lead contamination the exposure of children in Olomouc can represent 17 % of the exposure limit, in Karviná 14 %. In the case of the most contaminated kindergarten, the lead intake from the soil consumption could amount to 36 % of the exposure limit. Applying the upper end of the interval of potential soil consumption 800 mg/d in US EPA sources, an exposure even exceeding the exposure limit could occur. In the case of soil arsenic contamination, in a average contaminated kindergarten in Olomouc the contribution of arsenic could amount to 5 % of the exposure limit, in Karviná 5.4 %. In the most contaminated kindergarten, applying the upper limit of the soil ingestion interval a drawing of the exposure limit up to 31 % could occur. In the case of arsenic it is necessary to take into consideration also its significance to health from the point of view of its demonstrated carcinogenicity.
In the urban environment the contamination of upper soil with polycyclic aromatic hydrocarbons was found to be significant in view of health hazard by unintentional soil ingestion. The recommended maximum level of 1 mg PAHs/kg of soil was met by three samplings from the total of 72 kindergartens. A markedly higher contamination was found in soil samples of several kindergartens in Olomouc, that fact significantly influences the PAH selection characteristics for Olomouc in the negative sense. In PAHs unclassifiable by the US EPA as human carcinogens, there was found only a singularly exceeding of proposed maximum levels. In PAHs of the groups classified by the US EPA as demonstrated or probable carcinogens, on the contrary, numerous exceedings of the proposed limits for playgrounds were found. Increased levels are serious namely in benzo[a]pyrene. A theoretical estimate of increased probability of contracting cancer over a three years exposure signalizes the increased risk through regular soil ingestion, particularly in the most contaminated playgrounds.
Microbial soil contamination greater than permitted by criteria in Public Notice No. 464/2000 of the Ministry of Health, was detected in 40 % of kindergartens under follow-up. In respect to these results obtained by taking of composite samples in the microbial contamination monitoring, in the next stage of the study it will be appropriate to perform additional samplings of the kindergarten area in the form of an individual samples network, and at the same time to detect persisting contamination. On the basis of the pilot study and the associate study (NIPH Prague and Public Health Centre Ostrava) there has been revised and adjusted the methodology of sampling for the objective confirmation of microbiological contamination of soil in urban agglomerations.
The monitoring of soil contamination in urban agglomerations and the assessment of its significance is continuing in the year 2002 in the cities of Hradec Králové, Klatovy and Kroměříž.
Table 11.1 Upper soil metal concentration in Olomouc and Karviná kindergartens
|
Elements [mg/kg] |
|||||||
Pb |
Cd |
Cu |
Cr |
As |
Be |
V |
Hg |
|
OLOMOUC N = 45 |
||||||||
Median |
46.6 |
0.41 |
29.0 |
54.2 |
8.2 |
0.85 |
58.0 |
BD |
Mean (arithmetic) |
51.1 |
0.39 |
32.0 |
49.8 |
8.5 |
0.87 |
55.2 |
|
Maximum |
106.7 |
0.66 |
111.8 |
75.3 |
22.3 |
1.41 |
86.1 |
|
Minimum |
28.5 |
0.20 |
12.1 |
21.1 |
4.2 |
0.52 |
21.5 |
|
90th percentile |
78.9 |
0.51 |
43.8 |
67.1 |
10.2 |
1.12 |
73.8 |
|
Proposed limit in non-contaminated soils |
50 |
0.30 |
45 |
85 |
5 |
1.5 |
80 |
0.3 |
Number of schools above limit |
19 |
30 |
4 |
0 |
44 |
0 |
2 |
3 |
KARVINÁ N = 25 |
||||||||
Median |
46.8 |
0.61 |
20.1 |
58.2 |
9.1 |
1.88 |
52.2 |
BD |
Mean (arithmetic) |
48.2 |
0.68 |
22.0 |
55.7 |
9.1 |
1.93 |
52.7 |
|
Maximum |
84.5 |
1.32 |
38.8 |
68.4 |
12.6 |
2.80 |
65.3 |
|
Minimum |
30.8 |
0.40 |
15.1 |
38.4 |
6.2 |
1.20 |
33.0 |
|
90th percentile |
58.9 |
0.97 |
28.5 |
61.9 |
11.0 |
2.42 |
60.2 |
|
Proposed limit in non-contaminated soils |
50 |
0.3 |
45 |
85 |
5 |
1.5 |
80 |
0.3 |
Number of schools above limit |
9 |
25 |
0 |
0 |
25 |
23 |
0 |
1 |
BD: > 50 % of samples under the bound of determination
Table 11.2 Kindergartens’ upper soil PAH concentration unclassifiable by US EPA as human carcinogens (Group D)
|
PAHs [mg/kg] |
||||||||
Naphta- |
Acena- |
Ace- |
Fluorene |
Phenan- |
Anthra- |
Fluoran- |
Pyrene |
Benzo[g,h,i]- |
|
OLOMOUC N = 47 |
|||||||||
Median |
BD |
BD |
BD |
BD |
0.25 |
0.07 |
0.90 |
0.63 |
0.31 |
Mean (arithmetic) |
|
|
|
|
0.93 |
0.25 |
2.73 |
2.01 |
0.82 |
Maximum |
|
|
|
|
12.00 |
2.80 |
28.00 |
20.00 |
9.17 |
Minimum |
|
|
|
|
< 0.04 |
< 0.04 |
0.08 |
0.05 |
< 0.04 |
90th percentile |
|
|
|
|
2.14 |
0.36 |
6.55 |
4.93 |
2.41 |
Proposed limit |
1 |
5 |
5 |
5 |
10 |
10 |
10 |
10 |
1 |
Number of schools above limit |
1 |
0 |
0 |
0 |
1 |
0 |
1 |
2 |
7 |
KARVINÁ N = 25 |
|||||||||
Median |
0.26 |
BD |
BD |
BD |
0.21 |
BD |
0.57 |
0.54 |
0.19 |
Mean (arithmetic) |
0.52 |
|
|
|
0.49 |
|
1.14 |
0.93 |
0.34 |
Maximum |
3.78 |
|
|
|
3.43 |
|
4.88 |
4.61 |
1.60 |
Minimum |
< 0.04 |
|
|
|
< 0.04 |
|
0.16 |
0.14 |
0.06 |
90th percentile |
1.39 |
|
|
|
1.05 |
|
2.98 |
2.08 |
0.66 |
Proposed limit |
1 |
5 |
5 |
5 |
10 |
10 |
10 |
10 |
1 |
Number of schools above limit |
3 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
1 |
BD: > 50 % of samples under the bound of determination
Table 11.3 Kindergartens’ upper soil PAH concentration classified by US EPA as human carcinogens and probable or possible human carcinogens (Group A–C)
|
PAHs [mg/kg] |
||||||
Benzo[a]- |
Benzo[b]- |
Benzo[k]- |
Benzo[a]- |
Indeno- |
Di-benz[a,h]- |
Chrysene |
|
OLOMOUC N = 47 |
|||||||
Median |
0.34 |
0.43 |
0.45 |
0.61 |
0.36 |
0.06 |
0.50 |
Mean (arithmetic) |
0.92 |
1.54 |
1.13 |
1.65 |
1.34 |
0.16 |
1.49 |
Maximum |
7.69 |
18.67 |
11.01 |
18.88 |
19.86 |
1.50 |
15.92 |
Minimum |
< 0.04 |
0.05 |
0.04 |
0.05 |
0.04 |
< 0.04 |
0.05 |
90th percentile |
2.57 |
4.96 |
3.11 |
5.05 |
3.99 |
0.45 |
4.04 |
Proposed limit |
1 |
1 |
1 |
0.1 |
1 |
0.1 |
0.01 |
Number of schools above limit |
13 |
12 |
9 |
45 |
11 |
13 |
47 |
KARVINÁ N = 25 |
|||||||
Median |
0.32 |
0.34 |
0.17 |
0.31 |
0.31 |
0.05 |
0.18 |
Mean (arithmetic) |
0.53 |
0.52 |
0.27 |
0.49 |
0.49 |
0.07 |
0.31 |
Maximum |
2.39 |
1.62 |
0.90 |
1.82 |
1.59 |
0.28 |
1.21 |
Minimum |
0.09 |
0.11 |
0.05 |
0.09 |
0.04 |
< 0.04 |
0.05 |
90th percentile |
1.25 |
1.32 |
0.71 |
1.21 |
1.29 |
0.18 |
0.80 |
Proposed limit |
1 |
1 |
1 |
0.1 |
1 |
0.1 |
0.01 |
Number of schools above limit |
5 |
4 |
0 |
22 |
4 |
7 |
25 |
Table 11.4 Indicators of microbiological and parasitological soil contamination in kindergartens
|
Distribution of the kindergartens according to upper soil microbiological contamination |
|||||
< 101 KTJ |
101–102 * KTJ |
102–103 KTJ |
103–104 KTJ |
104–105 KTJ |
> 105 KTJ |
|
OLOMOUC N = 47 |
||||||
Thermotolerate colif. bacteria |
- |
42 |
5 |
- |
- |
- |
Enterococci |
- |
33 |
12 |
2 |
- |
- |
Yeasts, fungi |
- |
- |
- |
2 |
26 |
19 |
KARVINÁ N = 25 |
||||||
Thermotolerate colif. bacteria |
4 |
13 |
6 |
1 |
1 |
- |
Enterococci |
3 |
17 |
2 |
3 |
- |
- |
Yeasts, fungi |
- |
- |
- |
- |
24 |
1 |
* 102 CFU: public health limit value for thermotolerant coliform bacteria
and enterococci set in Regulation No. 464/2000 of the Ministry of Health,
suppl. No. 8 – evaluation of fecal pollution in playing fields.
The findings of Salmonella in upper soil samples were negative in all samples.
Table 11.5 Microbiological contamination of soil in relation to the sampling depth
Sampling point |
Sampling depth |
Microbiological contamination [CFU/g dry matter] |
||
Thermotolerate colif. bacteria |
Enterococci |
Yeasts, fungi |
||
1 |
0–5 |
< 50–750* |
< 50–750* |
2.9.104 |
5–10 |
< 50 |
< 50 |
6.4.103 |
|
10–20 |
< 50 |
< 50 |
1.7.103 |
|
2 |
0–5 |
< 50 |
< 50 |
7.9.104 |
5–10 |
< 50 |
< 50 |
4.5.104 |
|
10–20 |
< 50 |
< 50 |
7.0.103 |
* contamination sporadic, mean value lies within the concentration interval