8. BIOLOGICAL MONITORING AND THE RESULTS OF HUMAN EXPOSURE TO TOXIC SUBSTANCES FROM THE OUTDOOR ENVIRONMENT

8.1 Organization of monitoring activities

This subsystem comprises the monitoring of toxic substances and their metabolites (biomarkers of internal doses), and selected biological changes (biomarkers of biological effects) in biological material of population groups (adults, children aged 8–10 years and post-puerperal mothers in 4 selected regions: Benešov, Žďár nad Sázavou, Plzeň and Ústí n. Labem. Each monitored region comprises 100 persons from the monitored population group. Basic demographic data and information on lifestyle necessary for estimating population exposure to contaminants have been collected by means of a brief questionnaire. The subsystem is supplemented with monitoring of the mutagenic activity of particulate matter, fraction PM10 in ambient air.

Analytical laboratories are subjected to constant quality control of results produced. The majority of laboratories have CIA accreditation or at the accreditation stage. Inter-laboratory differences have been minimised by defining analyses according to matrix or analyte, respectively. Following the tender in 2000, the external cooperating facility where the analyses of PCBs and other organic compounds in breast milk were provided, has been replaced. The results obtained in this subsystem are presented for the particular population groups as summary data from all localities as basic descriptive statistics.

The biological exposure limits of toxic substances in human biological materials have not generally been established for the non-professionally exposed population. However, for some serious contaminants, a so-called maximum tolerable level has been established. Exceeding these values signalises a potential risk to population health. The homogeneity of data and their compatibility with data found in analogous studies along with the continuity of the Monitoring System allows their application for determination of reference values characterising the population burden. 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 environmental pollution.

8.2 Monitored factors

The factors monitored in 2002 include toxic metals (cadmium, mercury, lead, manganese) and trace elements (copper, selenium, zinc) in adult blood and (with the exception of manganese) adult urine, the urine and hair of children and (as a pilot study) in breast milk. Lead levels were monitored in the teeth of pre-school children. Children’s urine was also tested for presence of nitrates. Persisting chlorinated organic substances (indicator congeners of polychlorinated biphenyls – PCBs – and selected chlorinated pesticides) were analysed in breast milk and blood serum of adults. Ochratoxin A levels were monitored in blood serum as well. The bacterial mutagenicity of the PM10 fraction of particulate matter in ambient air was monitored.

8.2.1 Toxic metals and trace elements

Summarised results are presented in the form of basic descriptive statistics in Table 8.1. The values found are generally consistent with both the data present for other non-occupationally exposed population groups in literature and the data derived from previous monitoring activities.

The blood lead level with a median value of 29.0 µg/L in adults has decreased in comparison to the previous year (Fig. 8.1a). In 95 % of the adult population the blood lead level does not exceed 68.0 µg/L. The levels of lead are higher in men than in women. An estimate of reference values for the Czech Republic based on the results of the Monitoring System during 1996–2000 was 95 µg/L in men and 78 µg/L in women. The levels of lead in urine for adults (median and 95th percentile) is 3.1 and 21.1 µg/g of creatinine, in children the lead concentration in 75% of samples is below the determinability level of the method used. Likewise, results of Pb analyses in urine and child teeth have a declining tendency.

The blood cadmium level is a biomarker of current population exposure and is strongly influenced by the smoking habit. The median value in the adult population of 0.50 µg/L correlates with the results gained in the monitoring periods of recent years (Fig. 8.1b). The cadmium urine levels in adults represent long-term load; in 2001 the following values (median and 95% percentile) were measured: 0.34 and 1.27 µg/g creatinine, which correlates with previous monitoring periods. The values in the child population are 54 % below the detection limit. Estimates of reference Cd values for the Czech population are based on results of the Monitoring System during the 1996–2000 period and were 1.2 µg/L in the blood of adult no-smokers and 0.6 µg/L in the blood of children.

Mercury levels in blood do not signalise any increased burden in the adult Czech population (median 0.85 µg/L) (Fig. 8.1b), the same as concentrations of mercury in urine with a median of 0.53 µg/g creatinine in adults and 0.43 µg/g creatinine in children.

Blood copper levels in adults correlate with generally presented reference values and reference values estimated for the Czech population based on Monitoring System results in the 1996–2000 period. These are in the range of 970 µg/L (men) to 1,450 µg/L (women) (Fig. 8.1c) and do not indicate hyposaturation of the Czech population. Likewise, concentrations in urine (adult median 21 µg/g creatinine, child median 42 µg/g creatinine) correlate with regularly measured values.

Blood zinc levels in adults (median 6600 µg/L) are in relation to the values measured in previous monitoring periods and reference values estimated for the Czech Republic based on Monitoring System results during the 1996–2000 period. These are in the range of 8,575 µg/L (men) and 8,431 µg/L (women). Zinc concentrations in adult urine (median 375 µg/g creatinine) and children (median 470 µg/g creatinine) correlate with the results of the previous monitoring periods (Fig. 8.1d).

Selenium is considered to be an element with beneficial effects and its antioxidant potential plays a role in the protective mechanisms against oxidation stress and resulting disorders promoted by that process (cancer, cardiovascular and endocrine system diseases). The blood selenium level is an indicator of saturation with this element. Concentration in the range of 90–150 µg/L is considered optimal. Pure blood, as analysed during monitoring, contains elevated levels of selenium and a coefficient of 0.8 is used to adjust to the level of published results. Results obtained from monitoring up to 2001 have revealed a gradually increasing trend in the adult population. Concentrations measured in 2002 are practically the same as those in 2001 (median in 2001 was 91.5 µg/L in the adult population, 88.6 µg/L in 2002). The increasing trend of selenium in blood reflects increased intake in food as detected by subsystem IV – dietary exposure (Fig. 8.1e).

Results of analyses of children’s hair show stable data in correlation with results obtained in preceding years.

8.2.2 Toxic substances of organic origin

Summary results are presented in the form of descriptive statistics in Table 8.2. Monitoring of PCB indicator congeners in breast milk has confirmed the dominance of congeners 138, 153 and 180, which persist in the organism for long periods. However, singular high values in the series indicate the existence of individual local burden points. Over 50 % of other PCB congener values are below the detection limit. Results from the overall monitoring period (1994–2002) indicate a significant increase with age, independence of the chronological order of parturition and a significant decrease with time (Fig. 8.2a). Higher values have been detected in the region of Ústí n. Labem.

Values of hexachlorobenzene (HCB) in breast milk (median 89 µg/kg fat) reflect the long-term gradual decline in chlorinated substances. However, the sum of DDT with a dominant ratio of DDE has shown an increase in 2001, seen on the resulting value (median 421 µg/kg fat in 2001 and 380 µg/kg in 2002) (Fig. 8.2b).

Indicator PCB congeners and selected chlorinated pesticides were analysed in 2002 for the first time also in samples of adult blood serum (N = 147). The levels of these substances in blood and blood serum are considered the most obvious indicators of actual burden by these xenobiotics. Results confirm an excess of congeners 138, 153 and 180. The levels of the analysed substances and their relationships are not entirely the same as the values detected in breast milk.

Concentrations of the mycotoxin ochratoxin A analysed in blood serum were detected in 96 % of samples; values ranged from 0.1 to 1.3 µg/L of serum (median 0.30) (Fig. 8.1f).

8.3 Genotoxic effects of ambient air

Systematic monitoring of the mutagenic activity of airborne particulate matter (PM10) was started at the end of 1996 and has been carried out continually at 18-day intervals since 1997 in extension of the sampling of polycyclic aromatic hydrocarbons. In view of the significantly higher values demonstrated in winter months, sampling in 2002 was again limited to two periods: January–March and October–December. In 1999, sampling was terminated in Benešov and instated in Prague. Results from 2002 correlate with those from 2001, denoting a stabilisation of values. The results of mutagenic activity detected in the tester strain YG1041 signalise the increasing concentration of other chemical structures with mutagenic potential bound to particulate matter, namely nitroarenes. The insignificantly higher values in Žďár n. Sázava have not as yet been explained (Fig. 8.3a, 8.3b).

8.4 Partial conclusions

Biomarker levels are generally characterised by substantial individual variability, but are indicative of population exposure in general. In 2002, comparison of results from biological monitoring with existing or reference or critical values and data from similar studies shows that population burden by xenobiotics in the Czech population is generally consistent with the mean values in the European Union and basically falls within the range of recommended reference values. There is a confirmed declining trend of lead levels in blood, a declining tendency of cadmium and a stabilised, if not entirely optimal, saturation by selenium in the adult population. A slow but continuous decrease is seen in hexachlorobenzene concentrations and, since 2001, an increase of the sum of DDT in breast milk. The results of the mutagenic activity of airborne particulate matter (PM10) are generally stable after the previous increase.

Table 8.1 Content of metals and metaloids in human biological material, 2002

Number of measurements (N), Median (Me), 90th percentile (P90), 95th percentile (P95), Range of medians from all of the monitored cities (Benešov, Plzeň, Ústí n.L, Žďár n.S)

Biological material

Units

Cadmium

Lead

Mercury

Copper

Selenium

Zinc

Manganese

Adults
blood

N

µg/L

396

397

397

397

397

395

396

Me

0.5

29

0.85

860

88.6

6 600

6.60

P90

1.7

57

2.43

1 150

109.0

8 030

10.30

P95

2.3

68

3.59

1 362

114.0

8 605

11.80

Range of cities

0.4–0.5

26–37

0.52–1.19

820–895

82.0–93.8

6060–7155

6.25–7.10

Children
blood

N

µg/L

335

335

335

335

335

335

 

Me

0.34

3.1

0.53

21

15.3

375

 

P90

0.94

15.3

4.12

45

32.0

714

 

P95

1.27

21.1

6.45

52

39.0

865

 

Range of cities

0.16–0.51

2.4–4.5

0.23–1.54

13–28

10.0–17.4

269–458

 

Children
urine

N

µg/g cr

BD

BD

346

346

346

346

 

Me

 

 

0.43

42.0

17.7

470

 

P90

 

 

2.83

78.6

78.9

922

 

P95

 

 

3.96

93.4

127.0

1 013

 

Range of cities

 

 

0.29–0.97

20.0–58.7

11.3–35.2

331–635

 

Children
hair

N

µg/g

321

321

319

321

321

321

 

Me

0.11

1.2

0.20

9

0.25

120

 

P90

0.33

2.4

0.41

32

0.36

176

 

P95

0.45

3.2

0.50

49

0.41

197

 

Range of cities

0.09–0.12

1.1–1.2

0.14–0.28

9–11

0.23–0.28

113–128

 

Children
teeth

N

µg/g

 

177

 

 

 

 

 

Me

 

0.74

 

 

 

 

 

P90

 

1.59

 

 

 

 

 

P95

 

2.37

 

 

 

 

 

Range of cities

 

0.65–1.34

 

 

 

 

 

Breast
milk

N

µg/L

 

 

 

88

88

88

88

Me

 

 

 

461

11.4

4 328

4.94

P90

 

 

 

609

16.8

8 088

15.20

P95

 

 

 

694

17.8

8 749

21.30

Range of cities

 

 

 

421–501

10.3–12.3

1995–6590

3.33–11

BD: > 50 % of  samples under the bound of determination
cr – creatinine

Table 8.2 Content of organic contaminants in human biological material, 2002

Number of measurements (N), Median (Me), 90th percentile (P90), 95th percentile (P95), Range of medians from all the monitored cities (Benešov, Plzeň, Ústí n.L, Žďár n.S)

Biological material

Units

HCB

DDTs

PCB138

PCB153

PCB180

PCBs

Breast
milk

N

µg/kg fat

367

367

367

367

367

367

Me

89

380

175

137

149

470

P90

190

720

316

256

248

834

P95

240

847

384

320

305

1 004

Range of cities

81–120

350–400

119–250

103–199

127–188

370–660


Fig. 8.1a Blood lead level in adults
Fig. 8.1b Blood cadmium and mercury level in adults
Fig. 8.1c Blood copper level in adults
Fig. 8.1d Blood zinc level in adults
Fig. 8.1e Blood selenium level and dietary exposure in adults
Fig. 8.1f Ochratoxine level in adults blood
Fig. 8.2a Polychlorinated biphenyls in breast milk, median value 1994–2002
Fig. 8.2b Selected chlorinated organic pesticides in breast milk median value, 1994–2002
Fig. 8.3a Mutagenicity of airborne particulate matter, fraction PM10, winter season 2002
Fig. 8.3b Trend of urban air mutagenicity

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