8. RESULTS OF SUBSYSTEM 5: HEALTH CONSEQUENCES OF HUMAN EXPOSURE TO TOXIC POLLUTANTS IN THE ENVIRONMENT, BIOLOGICAL MONITORING, GENOTOXICITY TESTING |
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 (blood, urine, hair, teeth) 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 assessment of 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 matters in the ambient air (fraction PM10).
Laboratories carrying out the analyses undergo a systematic control of the quality of the results produced. 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 five year continuity of the Monitoring System render possible their application for determination of the reference values characterizing the burden to the population under any given circumstances. 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 Detection of toxic pollutants
Included among the factors monitored in 1998 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 hair of children, lead in teeth of children and nitrates in umbilical blood. Among the followed up contaminants of organic origin were polychlorinated biphenyls (PCBs) and selected chlorinated pesticides in mother’s milk, placenta and umbilical blood, phthalic acid derivatives in mother’s milk, aflatoxin M1 in urine of adults and ochratoxin A serum content in adults.
In a pilot study, contents of PCBs, polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) were monitored and expressed as toxic equivalent (I-TEQ) in pool samples of mother’s milk from individual aliquots collected in each of the localities studied.
8.2.1 Toxic metals, trace elements and nitrates
Summarized data are presented in the form of basic statistical descriptions in Tab. 8.1 and in Fig. 8.1a, 8.1b, 8.1c, 8.1d, 8.1e, 8.1f, 8.1g, 8.1h, 8.1i, 8.1j, 8.1k, 8.1l, 8.1m. 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 the findings of 1997. In 90% of the adult population, it does not exceed 71.0 µg/l. The lead content depends on the gender (higher values in males) and age. The population of children shows a median value of 34.0 µg/l and in 90% of the probands, it does not exceed 50.0 µg/l. The critical (tolerable) value of 100 µg/l was exceeded in 10 adults (2.5%) and 3 children (0.8%).
The cadmium contents of the blood and urine in adults and children have shown a certain downward tendency during the monitoring activities (Fig. 8.1c, 8.1d). Smoking significantly influences the cadmium levels of the blood and urine in adults. In 90% of the adult population, the Cd concentration of the urine does not exceed 1.33 µg/g creatinine and in 14 cases (3.8%), values exceeding 2 µg/g creatinine, considered to be maximum tolerable internal dose in the non-occupationally exposed population, were found. The cadmium level of the blood in children remains under the detection limit for more than 50% (57.6%) of the population studied and for 49% in the only samples of the locality Ústí n/L. The cadmium content of the urine in children ranged up to 0.53 µg/g creatinine in 90% of their population and a value higher than 2 µg/g creatinine was found in only one individual.
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. The results of the monitoring activities have repeatedly shown an upward tendency (Fig. 8.1i), namely in adults (median 88.5 µg/l).
The results of analysis of hair of children and of the lead content of their teeth (Fig. 8.1m) have shown stability and comparability with those of the previous years.
The nitrate levels of the umbilical blood serum (Fig. 8.1n) have been stable throughout the previous monitoring periods.
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). A significant downward tendency found in 1996 compared to 1994/95 slowed down markedly and the values found in 1998 are practically the same as those of 1997. Nevertheless, the isolated high values are indicative of the presence of an individual local spot burden. The other congeners monitored have shown substantially lower values, nevertheless, the levels of congeners 52 and 118 exhibited an upward tendency compared to 1997. Stable content has been observed in the PCB congeners levels of the umbilical blood serum, a more marked downward tendency has been recorded for the contents in placenta (Fig. 8.2d).
Analyses of the contents of polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) together with relevant PCB congeners in four pool samples of mother’s milk have confirmed that toxic PCB congeners account for almost 90% of the toxic equivalent (Fig. 8.2c). In agreement with analysis of indicator congeners, higher values have been recorded in the sample of Ústí n/L. The results represent first reference data of this kind obtained from population of the Czech Republic, needed for assessment of population burden from dioxins and dibenzofurans.
The values of chlorinated pesticides in mother’s milk have confirmed the downward tendency in exposure to these pollutants. Conversely, a markedly upward tendency has been observed in phthalic acid derivatives (di-n-butylphthalate - DBFT and di(2-ethylhexyl)phthalate - DEHFT) in mother’s milk (Fig. 8.2b).
Analysis of M1 aflatoxin (B1 aflatoxin metabolite) in the urine of adult population has shown statistically significantly higher levels in the localities of Benešov and Žďár n/S compared to those of Plzeň and Ústí n/L and thus confirmed the tendency found already in 1997 (Fig. 8.2e).
Content of another mycotoxin, ochratoxin A, was monitored in blood serum of adults. Analysis of the samples collected in 1997 was completed. The results obtained are in agreement with the data found previously and confirm a stable, but not very high, burden to population. The values recorded in 1994, 1995 and 1997 in Benešov and Žďár n/S are significantly higher compared to those of Ústí n/L.
8.3 Genotoxic effects of ambient air
Systematic monitoring of particulate matter (fraction PM10) mutagenic activity, extending the analysis of polycyclic aromatic hydrocarbons (PAH) within Subsystem 1, was started in the end of 1996 and went on at 18-day intervals throughout 1997 and 1998. The results of 1998 confirmed the presence of mutagenic pollutants in all samples analyzed with marked seasonal differences (Fig. 8.3), consistent with those of PAH analysis. Nevertheless, the results of mutagenic activity detected in the indicator strain YG1041 are suggestive of the presence of other chemical structures with mutagenic potential such as nitroarenes.
8.4 Partial conclusions
Biomarker levels are generally characterized by marked interindividual variability but are indicative of the exposure to the population 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 to the Czech population ranges within the European average. Positively should be seen the downward tendency in concentrations of important toxic metals (lead, cadmium) and continuous increase to optimal values of selenium levels in the blood. The PCB contents in the mother’s milk stabilized in 1998 and did not differ from those of the previous year. The mycotoxin burden to population is more marked in more agricultural localities. Statistically significant remains increase in the levels of phthalic acid derivatives in mother’s milk.
Tab. 8.1 Content of metals and metaloids in human biological materials, 1998
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 |
N |
µg/l |
394 |
395 |
395 |
395 |
395 |
395 |
|
blood |
Me |
6.00E-01 |
4.00E+01 |
5.80E-01 |
8.00E+02 |
8.85E+01 |
6.87E+03 |
NT |
|
|
Kv90 |
1.57E+00 |
7.10E+01 |
1.80E+00 |
9.70E+02 |
1.18E+02 |
8.85E+03 |
||
|
Range |
0.6 - 0.7 |
35.0 - 46.5 |
0.38 - 1.09 |
765 - 860 |
82.9 - 101 |
6 430 - 7 470 |
||
Adults |
N |
µg/g cr. |
366 |
366 |
366 |
366 |
366 |
366 |
|
urine |
Me |
3.70E-01 |
2.43E+00 |
5.50E-01 |
5.80E+00 |
1.07E+01 |
2.93E+02 |
NT |
|
|
Kv90 |
1.33E+00 |
6.60E+00 |
2.52E+00 |
2.83E+01 |
4.17E+01 |
5.96E+02 |
||
|
Range |
0.31 - 0.61 |
2.17 - 2.75 |
0.43 - 0.82 |
4.0 - 17.5 |
6.98 - 12.9 |
231 - 399 |
||
Children |
N |
µg/l |
384 |
384 |
384 |
384 |
384 |
384 |
|
blood |
Me |
1.50E-01 |
3.40E+01 |
3.90E-01 |
1.03E+03 |
6.70E+01 |
5.15E+03 |
NT |
|
|
Kv90 |
4.00E-01 |
5.00E+01 |
9.80E-01 |
1.25E+03 |
8.10E+01 |
6.64E+03 |
||
|
Range |
0.15 - 0.23 |
31 - 35 |
0.34 - 0.41 |
961 - 1 135 |
64.5 - 71.0 |
4 700 - 5 645 |
||
Children |
N |
µg/g cr. |
399 |
399 |
399 |
399 |
399 |
399 |
|
urine |
Me |
1.03E-01 |
2.03E+00 |
2.70E-01 |
3.67E+01 |
7.50E+00 |
5.26E+02 |
NT |
|
|
Kv90 |
5.30E-01 |
1.60E+01 |
2.13E+00 |
7.67E+01 |
3.00E+01 |
1.27E+03 |
||
|
Range |
0.07 - 0.18 |
1.61 - 2.34 |
0.20 - 0.40 |
23.0 - 41.7 |
6.5 - 9.1 |
279 - 627 |
||
Children |
N |
µg/g |
362 |
362 |
359 |
359 |
362 |
362 |
359 |
hair |
Me |
1.50E-01 |
1.50E+00 |
1.60E-01 |
9.00E+00 |
3.20E-01 |
1.34E+02 |
0.21 |
|
|
Kv90 |
5.00E-01 |
3.77E+00 |
2.80E-01 |
2.39E+01 |
7.90E-01 |
2.08E+02 |
0.44 |
|
|
Range |
0.11 - 0.23 |
1.28 - 1.82 |
0.15 - 0.18 |
8.0 - 11.0 |
0.295 - 0.30 |
119 - 165 |
0.20 - 0.23 |
Remark:
Symbol “cr.” means creatinine
Term 1.92E-01 = 0.192 or 1.92E+01 = 19.2
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 1998
Fig. 8.1a | Lead in blood, 1998 |
Fig. 8.1b | Lead in urine, 1998 |
Fig. 8.1c | Cadmium in blood, 1998 |
Fig. 8.1d | Cadmium in urine, 1998 |
Fig. 8.1e | Mercury in blood, 1998 |
Fig. 8.1f | Mercury in urine, 1998 |
Fig. 8.1g | Copper in blood, 1998 |
Fig. 8.1h | Copper in urine, 1998 |
Fig. 8.1i | Selenium in blood, 1998 |
Fig. 8.1j | Selenium in urine, 1998 |
Fig. 8.1k | Zinc in blood, 1998 |
Fig. 8.1l | Zinc in urine, 1998 |
Fig. 8.1m | Metals and metaloids in children hair and teeth, 1998 |
Fig. 8.1n | Nitrates in biological material, 1994 - 1998 |
Fig. 8.2a | Polychlorineted biphenyls (PCB) in mother’s milk, 1998 |
Fig. 8.2b | Organic compounds in mother’s milk, 1998 |
Fig. 8.2c | Selected organic compounds in mother’s milk, 1998, (recalculation on toxic equivalent, I-TEQ) |
Fig. 8.2d | Polychlorinated biphenyls (PCB) in umbilical blood and placenta, 1998 |
Fig. 8.2e | Aflatoxin M1 in urine, 1998 |
Fig. 8.3 | Mutagenicity in particulate matter - PM10, 1998 |