8. RESULTS OF SUBSYSTEM 5: HEALTH EFFECTS OF EXPOSURE TO TOXIC POLLUTANTS FROM THE ENVIRONMENT, BIOLOGICAL MONITORING

8.1 Organization of monitoring activities

This Subsystem includes the monitoring of toxic substances or their metabolites (biomarkers of internal dose), and selected biological alterations (biomarkers of biological effect) in the biological material of three population groups: adults, children (8-10 years old) and post-puerperal mothers in four selected regions: Benešov, Žïár n/S, Plzeò, and Ústí n/L. Basic demographic data and information on lifestyle necessary for estimating the population exposure to the contaminants have been collected by means of a brief questionnaire. The subsystem is supplemented with the monitoring of the mutagenic activity of particulate matter, fraction PM10, in the ambient air.

Inter-laboratory differences have been minimized by defining of analyses according to matrix or analyte, respectively. Following the tender in 2000, the external co-operating facility where the analyses of PCBs and other organic compounds in breast milk were provided has been replaced. The results obtained in the subsystem are presented for the particular population groups as summary data from all the localities under the monitoring by the form of basic descriptive statistic.

The biological exposure limits of toxic substances in human biological materials have not been mostly established for the non-professionally exposed population. However, for some serious contaminants, a so-called maximum tolerable levels has been determined. The exceeding of these values signalize potential risk to population health. The homogeneity of the data produced and their compatibility with the data found in analogous studies along with a several-year continuity of the Monitoring System allow their application for determination of reference values characterizing the burden of the population. A certain extent of individual variability may be caused by differences in the magnitude of exposure and the individual sensitivity of the human organism to the environmental pollution.

8.2 Monitored factors

Toxic metals (cadmium, mercury, lead) as well as selected trace elements (copper, selenium, zinc) were included among the factors monitored in 2000. They were determined in the blood and urine of adults, in the urine and hair of children. Lead concentrations were also measured in the teeth of children, and cadmium concentrations in kidney tissue. Newly, arsenic has been included among the monitored elements in the urine of adults and children, iodine has been monitored in the urine of adults and children (selected number of subjects) and fluorine in the urine of children as well. After a two years interruption, nitrates level have been investigated in the urine of children. From among contaminants of organic origin, indicator PCB congeners and selected chlorinated pesticides in the breast milk and subcutaneous fat, phthalic acid derivatives in breast milk were monitored. In the same samples of subcutaneous fat, PCBs, PCDDs and PCDFs having the dioxin activity have been analyzed, finally expressed as the total value of toxic equivalent (TEQ). In the sera of adults, the level of the mycotoxin ochratoxin A has been measured. Concerning the environmental genotoxicity, the bacterial mutagenicity of particulate matter (PM10 fraction) in the ambient air has been monitored.

8.2.1 Toxic metals and trace elements

Summarized results are presented in the form of basic statistical descriptions in Table 8.1. The values found are generally consistent with both the data presented for other non-professionally exposed population groups in the literature and the data derived from the previous monitoring activities.

The lead blood level with the median value of 43.0 µg/L in adults range in the lower part of the reference values established in the industrialized countries and is in agreement with findings in previous years (Fig. 8.1a). Lead blood level at 90 % of adults did not exceed the value of 80.0 µg/L. The lead blood content depends on gender (higher values in males) and age. The critical (tolerable) value of 100 µg/L was exceeded in 15 adults (3.8 %). On the basis of results obtained through the Monitoring System in the period 1996-2000, the reference lead blood values for the Czech population were estimated at 95 µg/L (males), 80 µg/L (females) and 60 µg/L (children). The lead urine levels in children have remained stable since 1997 (Fig. 8.1b).

During the monitoring activities, the cadmium blood and urine content in adults and children have shown a certain declining tendency (Fig. 8.1c). In adults, the median of cadmium blood concentration is 0.58 µg/L. This value increases significantly in smokers. Cadmium urine level in children is in total more than 69 % below the detection limit. Values exceeding 2 µg per g of creatinine, which is considered to be the maximum tolerable internal dose for the non-professionally exposed population were found in 18 urine samples (4.5 %) in adults. An estimate of reference values of Cd for the Czech population based on the Monitoring System results from the period 1996-2000 is 1.2 µg/L blood in adults and 0.6 µg/L blood in children. Cadmium was also analyzed in kidney tissue. In 1999 and 2000, 32 samples were analyzed; the cadmium level (median 18.5 mg/kg tissue) corresponded to those obtained in 1996 (median 14.2 mg/kg tissue).

Mercury levels in the blood and urine of adults and in the urine of children did not indicate any increased burden of our population by this element, and its values has ranged in agreement with those in the literature. On the basis of the Monitoring System results, the reference mercury blood level for the Czech population is estimated to be 2.8 µg/L in adults and 1.6 µg/L in children.

In the general population, total arsenic urine level was lower than 10 µg/L, usually in the range of 2.8-3.8 µg/L. Results obtained within the framework of the Monitoring System correspond to the normal levels for the non-professionally exposed population - the median value is 3.7 µg/g creatinine in adults, 3.2 µg/g creatinine in children.

Copper blood and urine levels are in agreement with generally presented reference values as well as with results from previous periods of monitoring. Reference values of copper in blood can be estimated on the basis of results from the Monitoring System in the period 1996-2000, for adults are ranging from 970 µg/L (males) to 1450 µg/L (females), for children 1350 µg/L.

Selenium is considered to be an element with beneficial effects and its antioxidant potential plays a role in protective mechanisms against oxidation stress and resulting disorders (cancer, cardiovascular diseases). The selenium content in blood is indicative of the organism saturation with this element. As optimal is considered the level interval between 70 and 100 µg/L. Results obtained during the monitoring activities reveal a gradually increasing trend with the median value in blood 90.6 µg/L (in adults) (Fig. 8.1d). Selenium levels in urine has been consistent with those in blood.

Zinc levels in the blood and urine were in relation with values found in previous periods of monitoring.

Iodine is an important trace element essential for thyroid hormone production. A suitable biomarker for determining iodine saturation in the population are ioduria determination (iodine level in the urine). Ioduria exceeding 100 µg/L indicates sufficient supply in the organism, values of 50-100 µg indicates moderate iodine deficiency, and values below 50 µg signalizes serious deficiency. While results obtained in children (median value 199 µg/g creatinine) can be considered as a sufficient saturation, in adults (median value 83 µg/g creatinine) they document moderate hyposaturation with this element.

Results of elemental lead analyses in children’s hair and children’s teeth show stable data in agreement with results in preceding years.

In 2000, the results of nitrates analyses were in agreement with those from 1997, when the last measurement was conducted. The median value was found to be 58 mg/g creatinine. The nitrates concentrations fluctuated in the range of the characteristic values for Central and Eastern Europe countries, determined as 38-109 mg/g creatinine in adult population.

8.2.2 Toxic substances of organic origin

Monitoring of the indicator PCB congeners in breast milk confirmed the predominance of congeners 138, 153, and 180 persisting in the organism for a long time. However, single high values in the set indicated the presence of individual local spot burdens. The other PCB congeners monitored were below the detection limit in more than 50 % of cases. In view of the replacement of the laboratory entrusted with analyses, the results obtained cannot be assessed from the point of temporal trends (Fig. 8.2a).

The content of di-n-butylphthalate (DBFT) in breast milk in the period 1994-2000 under monitoring is presented in Fig. 8.2b. The levels of chlorinated pesticides, HCB, sum of DDT in breast milk have confirmed the declining tendency in exposure to these contaminants (Fig. 8.2c).

The marker and toxic PCB congeners together with PCDDs and PCDFs have been also analyzed in the samples of subcutaneous fat. In view of the small number of samples taken and analyzed in 2000, the results are not presented in the form of descriptive statistics and they will be processed together with samples to be analyzed in 2001. Significant quotient of toxic PCB congeners in the total toxicity expressed by the value of TEQ is shown in Fig. 8.2d (results obtained in the period 1996-1999).

Mycotoxin ochratoxin A level in blood serum in adult population have been followed up after the two-year time out. The results obtained are in agreement with the values detected previously and they confirm a continuous but slight burden of the population with higher values in Benešov and Žïár n/S.

8.3 Genotoxic effects of ambient air

Systematic monitoring of the mutagenic activity of particulate matter (fraction PM10) started at the end of 1996 and has been carried out continually in 18-day intervals since 1997, following the sampling of polynucleus aromatic hydrocarbons (PAHs) within Subsystem 1. In view of the significantly higher values demonstrated in winter months, sampling was performed in two periods: January-March and October-December 2000. In 1999, PAHs monitoring in Benešov was terminated and replaced by sampling in Prague. Samples from the Prague region revealed significantly higher values than in other localities (Fig. 8.3a). The mutagenic activity of all samples, expressed by the number of revertants per m3, correlated with the results of PAHs analyses conducted within the framework of Subsystem 1 (the PAHs sum, the TEQ value, and the benzo(a)pyrene concentration). The results of mutagenic activity detected by the derivative of S. Typhimurium tester strain YG1041 signalize the elevating concentration of other chemical structures with mutagenic potential (namely nitroarenes) in particulate matter.

8.4 Partial conclusions

Biomarker levels are generally characterized by substantial inter-individual variability but they are indicative for the population exposure in general. In 2000, Based on comparison the biological monitoring results with the existing reference or critical values and the data of similar studies, there can be stated that the xenobiotic burden of the Czech population is generally consistent with the mean values in European population, and, in general, it corresponds to the suggested reference values. There has been confirmed a declining tendency of cadmium concentrations and altogether sufficient saturation with selenium. The marker PCB congeners content in the breast milk has been practically stabilized since 1997. However, because of the analytical laboratory replacement in 2000, a responsible evaluation from view of long-term trends is not possible. A slow continuous decrease in levels of hexachlorobenzene and the sum of DDT in breast milk has been observed. The level of ochratoxin A in the adult population has been stabilized and does not signalize a strong burden of the Czech population. Results of mutagenic activity of the organic extract of particular matter, PM10 fraction, confirm the higher values occurrence in samples taken in Prague, and the general upward trend at the tester strain YG1041.

Table 8.1 Content of metals and metaloids in human biological materials, 2000

number of measurements (N), median (Me), 90% quantile (Kv90) and range of median from all cities monitored (Benešov, Plzeò, Ústí n/L, Žïár n/S)

Biological material

Dimension

Cadmium

Lead

Mercury

Copper

Selenium

Zinc

Chromium

Iodine

Adults blood

N

µg/L

399

399

398

399

399

399

NM

 

Me

0.6

43

1.32

920

90.6

6 820

 

 

Kv90

1.5

80

2.71

1 110

114

8 272

 

 

Range

0.5–0.6

38–54.5

1.04–1.44

885–945

86.5–95.8

6 380–7 280

 

 

Adults urine

N

µg/g cr.

359

359

359

359

359

359

 

99

Me

0.3

4.59

0.69

6

8.8

355

 

83

Kv90

0.82

20.6

3.21

13.3

26.9

625

 

154

Range

0.24–0.36

2.83–11.79

0.40–1.02

5.1–8.7

6.51–13.9

335–372

 

73–104

Children urine

N

µg/g cr.

NM

384

384

384

384

384

NM

100

Me

NM

1.51

0.35

32.4

18.9

402

 

199

Kv90

NM

8.7

2.05

56.4

54.5

734

 

309

Range

NM

0.81–2.40

0.19–0.83

22.4–39.5

8.2–27

339–465

 

176–228

Children hair

N

µg/g

343

343

343

343

343

343

343

 

Me

0.12

1.5

0.26

12

0.23

118

0.21

 

Kv90

0.35

2.9

0.28

39

0.58

182

0.34

 

Range

0.10–0.15

1.2–1.8

0.23–0.28

10.0–13.0

0.2–0.3

98–142

0.20–0.23

 

Children teeth

N

µg/g

 

171

 

 

 

 

 

 

Me

 

1.39

 

 

 

 

 

 

Kv90

 

3.59

 

 

 

 

 

 

Range

 

1.23–3.38

 

 

 

 

 

 

Remark:

Symbol “cr.” means creatinine
Term “Range” means range of medians from individual cities of the Monitoring System
Term “NM” means that the given matrix was not follow-up in 2000

Fig. 8.1a Lead in blood, 1994–2000
Fig. 8.1b Lead in urine, median concentration, 1996–2000
Fig. 8.1c Cadmium in blood, median concentration, 1994–2000
Fig. 8.1d Selenium in blood, median concentration, 1994–2000
Fig. 8.2a Polychlorinated biphenyls in breast milk, 1994–2000
Fig. 8.2b Dibutylphthalate in breast milk, 1994–2000
Fig. 8.2c Selected chlorinated organic pesticides in breast milk median concentration, 1994–2000
Fig. 8.2d Proportion of dioxin effect compounds on the toxic equivalent (TEQ) in subcutaneous fat, 1994–1999
Fig. 8.3a Mutagenicity of particular matter, fraction PM10, winter season 2000
Fig. 8.3b Mutagenicity of particular matter, fraction PM10, monitored cities, 1997–2000

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