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 are 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 2003 include toxic metals (cadmium, mercury, lead, manganese) and trace elements (copper, selenium, zinc) in adult blood and (with the exception of manganese) adult urine and the urine and hair of children. Lead levels were monitored in the teeth of pre-school children. Persisting chlorinated organic substances (indicator congeners of polychlorinated biphenyls – PCBs – and selected chlorinated pesticides) were analysed in breast milk. Ochratoxin A levels were monitored in adult blood. 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 Tab. 8.1. The values found are generally consistent with both data for other non-occupationally exposed population groups in literature and the data derived from previous monitoring activities.

Neurobehavioral and developmental changes may occur in young children at blood lead values of 100 µg/L or even less; monitoring has not detected such levels. The blood lead level with a median value of 32.0 µg/L in adults correlates to previous years. In 95 % of the adult population the blood lead level does not exceed 69.5 µg/L. The levels of lead are higher in men than in women. The levels of lead in urine for adults (median and 95th percentile) is 2.67 and 20.4 µg/g of creatinine, in children the lead concentration in 92 % 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.

Cadmium has an exceptionally long biological half-life (15–30 years) and consequent ability to accumulate in the organism. Its dangerous effects include nephrotoxicity and carcinogenicity, and, on interaction with calcium, osteoporosis and osteomalacia. The blood cadmium level is a biomarker of current population exposure and is influenced by the smoking habit (Tab. 8.1). The median value in the adult population of 0.40 µg/L correlates with results gained in the monitoring periods of recent years. The cadmium urine levels in adults represent long-term load; in 2003 the following values (median and 95th percentile) were measured: 0.28 and 1.31 µg/g creatinine, which correlates with previous monitoring periods. The values in the child population are 61 % below the determinability level.

Of existing form of mercury, methyl-mercury has the most serious adverse effects on health due to its neurotoxicity. Mercury levels in blood do not signalise any increased burden in the adult Czech population (median 0.96 µg/L) (Fig. 8.1a), the same as concentrations of mercury in urine with a median of 0.70 µg/g creatinine in adults and 0.28 µg/g creatinine in children.

Copper is contained in a number of antioxidant enzymes and plays a role in hematopoiesis and lipid metabolism. The effects of copper are determined in relation to zinc and iron content in the organism. Blood copper levels in adults (median 880 µg/L) detected in 2003 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). Likewise, concentrations in urine (adult median 14.2 µg/g creatinine, child median 24.1 µg/g creatinine) are lower than the values measured in 2002.

Zinc is likewise an essential element contained in a number of enzymes and plays a role in immune function and antioxidant processes. Blood zinc levels in adults (median 6,380 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 287 µg/g creatinine) and children (median 518 µg/g creatinine) correlate with the results of previous monitoring periods.

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 in blood serum. Whole 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, subsequent stabilisation of values in 2002, and continued increase during 2003 (Fig. 8.1b).

Results of trace elements analyses in children’s hair (Tab. 8.1) 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 Tab. 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. Other PCB congener values are over 50 % below the detection limit. Isolated high values in the series indicate the existence of local foci of burden. Results from the overall monitoring period (1994–2003) indicate a significant increase with age and independence from the chronological order of parturition. The decrease with time recorded in the 1994–2001 period stabilised during 2002–2003 (Fig. 8.2a). Higher values continue to be detected in the region of Ústí n. Labem.

Values of hexachlorobenzene (HCB) in breast milk (median 44 µg/kg fat) reflect the long-term gradual decline of this substance. Following an increase in the sum of DDT and DDE in 2001 and 2002, the current trend is on the decline (Fig. 8.2b).

8.3 Cytogenetic analysis of peripheral lymphocytes

Cytogenetic analysis of peripheral lymphocytes used for biological monitoring of population groups enables the detection of active genotoxic substances in the environment and indication of individual resistance to, and compensation of, genotoxic burden. Values of chromosomal aberrations that are significantly higher than reference values for given monitored population groups may reveal increased exposure to genotoxic substances from the environment. Results of cytogenetic analysis for 2001 (Tab. 8.3) correlate with values detected in 1999 and denote a stabilization of exposure to genotoxic substances and environmental factors, as well as population ability to resist such burden.

8.4 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 PAH analyses in subsystem I. In view of the significantly higher values demonstrated in winter months, sampling was again limited to two periods: January–March and October–December. Results from the 2003/2004 period correlate with those from previous years. 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 (Fig. 8.3a, 8.3b).

8.5 Partial conclusions

Biomarker levels are generally characterised by substantial individual variability, but are indicative of population exposure in general. In 2003, 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 an improving trend of selenium saturation in the adult population. A slow but continuous decrease is seen in hexachlorobenzene concentrations and, following a temporary increase in the 2001–2002 period, continued decrease of the sum of DDT. Values for chromosomal aberrations are stabilised. The results of the mutagenic activity of airborne particulate matter (PM10) are generally stable, despite signs of an increasing trend which should be the subject of further research.

Tab. 8.1 Content of metals and metalloids in human biological material, 2003

Number of samples (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

Unit

Cadmium

Lead

Mercury

Copper

Selenium

Zinc

Manganese

Smokers

Non-smokers

Adults blood

N

µg/L

115

281

396

395

396

395

396

396

Me

1.1

0.3

32

0.96

880

116

6,380

11.2

P90

3.26

0.7

55

2.11

1,195

159

7,600

17

P95

3.83

0.9

69.5

3.11

1,400

169

7,893

21.3

Range of cities

0.4–0.5

0.4–0.5

26–36

0.72–1.41

830–900

97.8–132.0

5,980–6,705

11.0–12.3

Adults urine

N

µg/g cr

322

322

322

322

322

322

 

Me

0.28

2.67

0.7

14.2

11

287

 

P90

1.01

13.5

4.08

30.6

24.6

602

 

P95

1.31

20.4

6.8

43

32.4

698

 

Range of cities

0.14–0.48

2.18–3.53

0.43–1.62

11.3–17.4

8.4–15.3

257–438

 

Children urine

N

µg/g cr

BD

BD

270

270

270

270

 

Me

0.28

24.1

14

518

 

P90

2.34

54.6

25.9

963

 

P95

4.46

74.7

29

1,088

 

Range of cities

0.20–0.33

15.3–36.0

12.9–14.8

462–584

 

Children hair

N

µg/g

292

292

292

292

292

292

 

Me

0.12

1.2

0.14

11

0.34

132

 

P90

0.34

2.5

0.32

48

0.71

180

 

P95

0.49

3.4

0.5

73

0.82

198

 

Range of cities

0.10–0.15

1.1–1.6

0.13–0.16

9.0–17.0

0.32–0.37

119–137

 

Children teeth

N

µg/g

 

60

 

 

 

 

 

Me

0.63

 

 

 

 

 

P90

1.57

 

 

 

 

 

P95

1.63

 

 

 

 

 

Range of cities

0.56–0.75

 

 

 

 

 

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

Tab. 8.2 Content of organic contaminants in human biological material, 2003

Number of samples (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

Unit

HCB

DDTs

PCB138

PCB153

PCB180

PCBs

Breast
milk

N

µg/kg fat

253

253

253

253

253

253

Me

44

288

132

174

139

460

P90

98

464

235

301

238

806

P95

116

498

271

343

265

886

Range of cities

36–55

181–343

100–171

121–228

105–183

333–598

Tab. 8.3 Cytogenetic analysis – chromosomal aberrations in peripheral lymphocytes of children and adult blood, 1993–2001

Number of samples (N), mean values (% AB.C.), standard deviation (SD), children (age group 8–12), adults (age group 21–45)

 

N

% AB.C.

SD

Range of values

1993

Children

Adults

179

2.05

1.41

0–6.00

1994

Children

680

1.29

1.32

0–11.00

Adults

626

1.40

1.30

0–7.00

1995

Children

459

1.23

1.33

0–11.00

Adults

1996

Children

350

0.92

1.00

0–5.00

Adults

330

1.04

0.98

0–5.00

1999

Children

338

1.14

1.17

0–5.00

Adults

366

1.06

1.01

0–5.00

2001

Children

351

1.10

1.12

0–5.00

Adults

392

1.26

1.08

0–6.00


Fig. 8.1a Blood cadmium and mercury levels in adults
Fig. 8.1b Blood selenium level in adults
Fig. 8.2a Polychlorinated biphenyls in breast milk
Fig. 8.2b Selected chlorinated pesticides in breast milk
Fig. 8.3a Mutagenicity of airborne particulate matter, fraction PM10, winter season 2003/2004
Fig. 8.3b Trend of urban air mutagenicity

Main page

CONTENTS