8. RESULTS OF SUBSYSTEM 5: HEALTH CONSEQUENCES OF HUMAN EXPOSURE TO TOXIC POLLUTANTS IN THE ENVIRONMENT, BIOLOGICAL MONITORING

8.1 Organization of the monitoring activities

The subsystem includes the monitoring of toxic substances or their metabolites (biomarkers of internal dose) and that of selected biological alterations (biomarkers of biological effect) in the biological material of the population groups of adults, children (8 - 10 year-olds) and postnatal mothers of four regions: Benešov, Žďár n/S, Plzeň and Ústí n/L. Basic demographic data and information on lifestyle, necessary for estimating the population exposure to the contaminants under study, are collected from the subjects under study through a brief questionnaire. The subsystem has been supplemented with the monitoring of mutagenic activity of particulate matter, fraction PM10, in the ambient air.

Defining the analyses according to the matrices and contaminants respectively minimizes interlaboratory differences. Results are presented for all population groups in all localities under monitoring in the form of basic descriptive statistics.

Mostly, the biological exposure limits for the toxic substances contents of human biological materials have not been established for the non-occupationally exposed population. However, a so-called maximum tolerable content has been determined for certain important contaminants, the exceeding of which signalizes potential risk to population health. The homogeneity of the data produced and their comparability with the data found in analogous studies from abroad, along with a six year continuity of the Monitoring System render possible their application for determination of the reference values characterizing the burden to the population in the given period. A certain degree of individual variability may be caused by differences in the magnitude of exposure and individual sensitivity of the human organism to contaminants in the environment.

8.2 Factors under follow-up

Included among the factors monitored in 1999 were toxic metals (cadmium, mercury, lead) as well as selected elements having beneficial effects (chromium, copper, selenium, zinc) in the blood and urine of adults and children, in the hair of children, lead in the teeth of children. Among the followed up contaminants of organic origin were congeners of polychlorinated biphenyls (PCBs) and selected chlorinated pesticides and phthalic acid derivatives in mother’s milk, as well as PCB indicator congeners and selected chlorinated pesticides in subcutaneous fat. Those same samples of subcutaneous fat were analyzed for congeners of PCB, PCDD and PCDF having dioxin activity, and that was expressed as the total value of their toxic equivalent (TEQ). As a biomarker of exposure to genetoxic factors, after three years, there was again included the cytogenetic analysis of peripheral lymphocytes. Concerning factors in the environment, there is being followed up the bacterial mutagenicity of the PM10 fraction of particulate matter aerosol in the ambient air.

8.2.1 Toxic metals and trace elements

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

The lead content of the blood (Fig. 8.1a) with a median value of 40.0 µg/l in adults ranges in the lower part of the reference values established in the industrialized countries and is in agreement with findings in preceding years. In 90 % of the adult population, it does not exceed 78.0 µg/l. The lead content depends on the gender (higher values in males) and age. The population of children shows a median value of 36.0 µg/l and in 90 % of the probands, it does not exceed 52.0 µg/l. The critical (tolerable) value of 100 µg/l was exceeded in 10 adults (2.5 %) and 3 children (0.8 %). On the basis of results obtained through the Monitoring System in the period 1996 - 1999, there can be estimated for the Czech population reference values of 95 µg/l (males), 80 µg/l (females) and 60 µg/l (children). The levels of lead in the urine of children are below the detection limits in more than 50 % of cases (Fig. 8.1b).

The cadmium content in the blood and urine in adults and children has shown a certain downward tendency during the monitoring activities (Fig. 8.1c, 8.1d). In adults the median concentration of cadmium in the blood is 0.5 µg/l (0.6 µg/l in 1998). Cadmium levels in the blood and urine in the child population are in more than 50 % of the whole series (74 % blood, 70 % urine) below the detection limit. Values exceeding 2 µg/g creatinine which is considered to be the maximum tolerable internal dose for the nonprofessionally exposed population, were found in seven samples (1.8 %) of urine from children. An estimate of reference values of Cd for our population, based on results from the Monitoring System for the period 1996 - 1999, is 1.2 µg/l in the blood of adults and 0.6 µg/l in the blood of children.

Mercury levels in the blood and urine do not signalize any increased burden in our population with this element and are in the range of values given in the literature (Fig. 8.1e and 8.1f). On the basis of the Monitoring System, the values of Hg in the blood can be estimated for the Czech adult population to be 2.8 µg/l of blood and for children 1.6 µg/l.

Copper levels in the blood and urine (Fig. 8.1g and 8.1h) are in agreement with generally presented reference values as well as with results from previous periods of monitoring. The results do not point to any hyposaturation of our population with this element. Reference values of Cu in the blood can be estimated on the basis of results from the Monitoring System in the years 1996 - 1998, for our adult population to be 970 µg/l (males) - 1 450 µg/l (females) and for children up to 1 350 µg/l.

Selenium is considered as 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 of the blood is indicative of the organism saturation with this element. Ideally, this concentration should range between 70 and 100 µg/l. Results obtained during the period of monitoring activities in recent years (Fig. 8.1i) reflect values approximating the optimum for the adult population (median 79.3 µg/l) as well as for the child population (median 69.0 µg/l). Selenium levels in the urine are in harmony with those in the blood (Fig. 8.1j).

Zinc levels in the blood and urine are in relation with values found in previous periods of monitoring (Fig. 8.1k and 8.1l). The results of analyses of hair of children and the lead content of their teeth (Fig. 8.1m) have shown stability and comparability with those in previous years.

8.2.2 Toxic substances of organic origin

Monitoring of the indicator PCB congeners in mother’s milk confirmed the prevalence of 138, 153 and 180 congeners persisting in the organism for a long time (Fig. 8.2a). Values of the median have remained practically the same since 1997. Nevertheless, the isolated high values in the sets are indicative of the presence of an individual local spot burden. The other congeners monitored showed substantially lower values, nevertheless, the levels of congener 52 exhibited an upward tendency compared to 1998.

The values of chlorinated pesticides in mother’s milk have confirmed the downward tendency in exposure to these pollutants. A markedly upward tendency is still being observed in phthalic acid derivatives (di-n-butylphthalate - DBFT and di(2-ethylhexyl)phthalate - DEHFT) in mother’s milk (Fig. 8.2b). However, in the case of DEHFT, in 1999 there was observed a lower median level than in 1998.

PCB congener levels in subcutaneous fat, in agreement with results of analyses of mother’s milk, are the highest in congeners 138, 153 and 180. In as the burden of these compounds increases with age, the values of these congeners, just like those of chlorinated pesticides, are higher in subcutaneous fat than in mother’s milk (Fig. 8.2c and 8.2d).

Analyses of PCDD and PCDF levels along with toxicologically important PCB congeners analyzed since 1996 in a total of 61 samples of subcutaneous fat, confirm that toxic PCB congeners have a significant share in the overall TEQ value. The results represent essential preliminary data for the assessment of the dioxin and dibenzofurane load in the Czech population (Fig. 8.2e).

8.3 Genotoxic effects of ambient air

Systematic monitoring of the mutagenic activity of particulate matter (fraction PM10), extending the analysis of polycyclic aromatic hydrocarbons (PAH) within Subsystem “Air”, was started at the end of 1996 and has been conducted at 18-day intervals since 1997. The results of 1999 confirmed the presence of mutagenic pollutants in all samples analyzed with markedly higher values in the winter season (Fig. 8.3a), consistent with those of PAH analysis. The results of mutagenic activity detected in the indicator strain YG1041 are suggestive of the increasing presence of other chemical structures with mutagenic potential (namely nitroarenes) bound to particulate matter.

8.4 Cytogenetic analysis of peripheral lymphocytes

Cytogenetic analysis of peripheral lymphocytes implemented in the biological monitoring of population groups facilitates the demonstration of the presence of genotoxically active substances in the environment and to indicate in the sets under follow-up the degree of the ability of individuals to tolerate a burden and to compensate for it with the aid of protective mechanisms. Significantly higher levels of chromosomal aberrations than the reference values for individual population groups under follow-up may signalize in this way a significantly increased exposure to genotoxic substances from the community environment.

Hitherto gathered results indicate that quotient of aberrant cells in the population groups followed up in four localities (Tab. 3.1) in the years 1993 - 1996 and 1999 are in agreement with reference values of population groups in the whole Czech Republic. Since 1994 there has been registered a significant decreasing trend in the frequency of aberrant cells, which testifies on the one hand to the decreasing content of genotoxic substances in the environment, and on the other hand, to the greater tolerance of the population to the existing genotoxic burden from the environment (Fig. 8.3b).

8.5 Partial conclusions

Biomarker levels are generally characterized by marked interindividual variability but are indicative of the population exposure as a whole. Based on the comparison of the biological monitoring results with the existing reference or critical values and the data of similar studies, it can be stated that the xenobiotic burden from the environment on the Czech population ranges within the European average.

On the basis of results obtained, it is already possible to estimate reference values of the contaminants for the Czech population. Positively should be viewed the downward tendency in concentrations of important toxic metals (lead, cadmium) and a sufficient saturation with selenium. The indicator PCB congener content in mother’s milk has practically stabilized since 1997. Statistically significant remains the increase in levels of phthalic acid derivatives in mother’s milk.

Results of the analysis of PCB indicators, PCDD and PCDF with dioxin activity reveal a marked preponderance of PCB congeners in the overall TEQ value and represent the first integrated data of this kind in our country. Results of cytogenetic analyses in 1999 confirm the values of chromosomal aberrations from preceding periods of monitoring.

Tab. 8.1 Content of metals and metaloids in human biological materials, 1999

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

Biological material

Dimension

Cadmium

Lead

Mercury

Copper

Selenium

Zinc

Chromium

Adults
blood

N

µg/l

399

399

398

399

399

399

 

Me

5.00E-01

4.00E+01

8.10E-01

9.10E+02

7.93E+01

6.59E+03

NT

Kv90

1.30E+00

7.80E+01

1.82E+00

1.16E+03

9.80E+01

8.50E+03

 

Range

0.5 - 0.6

35 - 45

0.66 - 0.93

800 - 990

75.1 - 83.0

5 930 - 7 450

 

Children
blood

N

µg/l

358

358

362

358

358

358

 

Me

1.50E-01

3.60E+01

3.80E-01

1.04E+03

6.90E+01

5.03E+03

NT

Kv90

4.00E-01

5.20E+01

9.40E-01

1.22E+03

8.10E+01

5.96E+03

 

Range

0.15

34 - 37

0.32 - 0.43

961 - 1 107

65.0 - 72.5

4 924 - 5 192

 

Children
urine

N

µg/g cr.

393

393

393

393

393

393

 

Me

1.20E-02

3.00E-01

2.80E-01

3.04E+01

1.67E+01

4.28E+02

NT

Kv90

3.49E-01

4.00E+00

1.29E+00

6.76E+01

6.40E+01

8.01E+02

 

Range

0.01 - 0.021

0.22 - 0.40

0.18 - 0.41

23.5 - 38.3

5.6 - 36.1

377 - 508

 

Children
hair

N

µg/g

360

360

360

360

360

360

360

Me

1.50E-01

1.40E+00

1.60E-01

1.10E+01

3.10E-01

1.23E+02

0.2

Kv90

3.50E-01

2.90E+00

2.80E-01

3.90E+01

5.80E-01

1.82E+02

0.34

Range

0.13 - 0.18

1.2 - 1.8

0.13 - 0.20

9.0 - 15

0.27 - 0.34

107 - 144

0.19 - 0.20

Remark:

Symbol “cr.” means creatinine.
Term “Range” means range of medians from individual cities of the Monitoring System.
Term “NT” means that the given matrix was not follow-up in 1999.

Fig. 8.1a Lead in blood, 1994 - 1999
Fig. 8.1b Lead in urine, 1994 - 1999
Fig. 8.1c Cadmium in blood, 1994 - 1999
Fig. 8.1d Cadmium in urine, 1994 - 1999
Fig. 8.1e Mercury in blood, 1994 - 1999
Fig. 8.1f Mercury in urine, 1994 - 1999
Fig. 8.1g Copper in blood, 1994 - 1999
Fig. 8.1h Copper in urine, 1994 - 1999
Fig. 8.1i Selenium in blood, 1994 - 1999
Fig. 8.1j Selenium in urine, 1994 - 1999
Fig. 8.1k Zinc in blood, 1994 - 1999
Fig. 8.1l Zinc in urine, 1994 - 1999
Fig. 8.1m Metals and metaloids in children hair and teeth, 1994 - 1999
Fig. 8.2a Polychlorinated biphenyls in mother’s milk, 1994 - 1999
Fig. 8.2b Selected organic compounds in mother’s milk, 1994 - 1999
Fig. 8.2c Polychlorinated biphenyls in subcutaneous fat, 1994 - 1999
Fig. 8.2d Selected organic compounds in subcutaneous fat, 1994 - 1999
Fig. 8.2e Toxic equivalent (I-TEQ) of selected organic compounds in subcutaneous fat, 1994 - 1999
Fig. 8.3a Mutagenicity in particulate matter, fraction PM10, 1999
Fig. 8.3b Cytogenetic analysis, 1994 - 1999

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