Lead exposure of the child population in Greece

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The Scienceof the Total Environment 158 (1994)79-83

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Lead exposure of the child population in Greece C. M a r a v e l i a s *a, S. A t h a n a s e l i s a, L. P o u l o s a, G . A l e v i s o p o u l o s a, U . E w e r s b, A. Koutselinis a aDepartment of ForensicMedicine and Toxicology, Universityof Athens, School of Medicine, 75 M. Asias St. Goudi, Athens 115 27, Greece bMedizinisches Institut fiir Umwelthygienean der UniversitiitDiisseldo~ Aufm Hennekamp 50, D-4000 Diisseldorf1, Germany

Received 17 December 1993;accepted 12 April 1994

Abstract Lead exposure of the child population was studied in three different areas in Greece: Kalamata which is a rural area of Southern Greece; Tavros, a district of Athens with a considerable industrial activity; and Lavrion, a small city near Athens where a lead-zinc mining and smelting industrial complex has existed for more than 90 years. The results were evaluated with respect to a number of individual, social and environmental variables (i.e. smelter, occupation of the father) especially those concerning the area of Lavrion which is the most heavily polluted area in Greece. The results of this study can be considered as an index for the extent of the lead pollution problem in the named areas of Greece. Keywords: Blood lead; Children; Environmental exposure

I. Introduction Environmental lead pollution is a worldwide problem. In recent decades several surveys have been carried out in order to estimate the lead exposure of human populations and to evaluate the consequences of this exposure for their health (Zielhuis et al., 1979; Roels et al., 1980; Cavalieri et al., 1981; Drossos et al., 1982; Brockhaus et al, 1983, 1988; Elinder et al., 1983; Ewers et al.,

1984, 1988; Claeys-Thoreau et al., 1987; Englert et al, 1987; Hatzakis et al., 1987; Needleman, 1992). There is a general agreement that children are a population at increased risk with respect to lead exposure according to well-defined criteria (Duggan, 1983; Ewers et al., 1988; Needleman, 1992 Wietzman et al., 1993; Ruff et al., 1993). According to these criteria and due to the fact that no other relative study has been designed to evaluate the blood lead levels (PbB) in the child population in Greece, this work was undertaken in order to be able to study the size of lead

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C. Maravelias et al. / Sci. Total Environ. 158 (1994) 79-83

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pollution problem in three different areas of Greece. 2. Study areas

The study areas were Koroni, a rural area of southern Greece; Tavros, a suburb of Athens surrounded by industrial complexes; and Lavrion, a heavily polluted town located 60 km south-east of Athens. The study was initiated in the area of Lavrion, where a lead-zinc mining and smelting industrial complex exists and where previous studies have reported serious pollution problems (Maravelias et al., 1989). Children at the four primary schools of the town were studied. Of these schools, one (No. 3) is located very close to the plant ( < 500 m), another (No. 1) is located at a distance of ~ 900 m from the smelter and the other two (Nos. 2 and 4) at distances of ~ 1500 m. After the completion of this part of the study, a small part of the child population of rural and urban areas of Greece (Koroni and Tavros) were studied and their PbB concentrations was compared with PbB concentrations of the children of Lavrion in order to estimate the extent of lead pollution in the above areas.

tometry as described by Brockhaus et al. (1983) using a Perkin-Elmer Model 5000 instrument equipped with a Perkin-Elmer H G A 500 atomiser. The method applied was the deproteinization method developed by Stoeppler et al. (1978). Each blood sample was analysed in duplicate. All PbB determinations were carried out at the Medical Institute for Environmental Hygiene of the University of Diisseldorf. All analyses were carried out under conditions involving internal and external quality control. For internal quality control, commercially control materials (control blood for metals; BehringWerke, Marburg, Germany) were used. The accuracy of the PbB determinations was confirmed on several occasions by participation in interlaboratory comparison programmes.

3.1. Statistical anakysis The frequency distributions of the biological exposure indices are presented in the form of percentiles (Ps0, P90, P98). The association between PbB and certain demographic, social and environmental variables was examined by simple univariate tests. Differences of group means were evaluated for significance by Student's t-test. 4. Results

3. Materials and methods

All materials used in this study (syringes, needies, test tubes, reagents, etc) were previously checked to ensure they were free of lead contamination. Blood samples were collected by venipuncture using polypropylene tubes containing EDTA as anticoagulant. The blood samples were deep frozen and stored at -20°C until analysed. The PbB concentrations were measured by graphite furnace atomic absorption spectropho-

The results of our study from a rural and an urban area of Greece are indicative of the background 'normal' PbB levels of the child population in these areas. Table 1 shows the PbB levels of the child population of Koroni (the rural area). The mean PbB value for all children was 8.4 + 2.5 /zg/dl which is expected for a population living in a rural area. Surprisingly, this value is a little higher than the respective mean value for the child population of Tavros (the urban area), which was

Table 1 Blood lead levels (/~g/dl) of child population in Koroni, Greece Group

n

GM

(95% CI)

Ps0

P90

P9s

Range

Boys Girls Total

24 19 43

8.6 8.1 8.4

(7.6-9.8) (7.2-9.0) (7.7-9.1)

7.8 7.9 7.9

13.4 10.6 12.9

14.4 11.3 14.4

5.9-15.9 5.1-11.4 5.1-15.9

C. Maravelias et al. /Sci. Total Environ. 158 (1994) 79-83

81

Table 2 Blood lead levels (p,g/dl) of child population in Tavros, Greece Group

n

GM

(95% CI)

Ps0

Pg0

Pgs

Range

Boys Girls Total

58 56 114

6.8 6.2 6.5

(6.4-7.3) (5.9-6.6) (6.2-6.8)

6.7 6.0 6.3

9.2 8.7 8.1

12.1 11.1 11.7

4.4-13.4 4.2-11.4 4.2-13.4

found to be 6.5 + 1.8/zg/dl as shown in Table 2. This difference was statistically significant (P < 0.001) and the difference could be attributed to local factors and conditions such as quality of water, quality of soil, pipes of the water system, etc. No statistically significant differences were observed between boys and girls concerning their PbB levels. However, this may be due to the small number of samples that were available (Koroni, n = 24, n = 19;Tavros n = 58, n = 56; boys and girls, respectively). A greater number of samples (514) was collected at Lavrion where higher blood lead levels were expected and a more thorough statistical analysis of the results was performed. Table 3 shows the blood lead levels of the children of Lavrion. The mean PbB value for all children was 21.7 + 10.1 tzg/dl. On average, boys had significantly higher PbB levels than girls, as shown in Table 3 (P < 0.01). Individual PbB levels were as high as 79.8 /zg/dl. The 50th, 90th, and 98th percentiles exceeded the PbB reference levels established by the CEC directive on biological screening of the general population for lead (CEC, 1977). As shown in Table 4, children who attended the elementary school (No. 3), located very close to the lead smelter, had on average significantly higher PbB levels than the children attending the other primary schools of the town (P < 0.001). As a rule, children attend the school that is

closest to their home, hence children attending school No. 3 also lived very close to the lead-zinc smelter. Table 5 shows that children of unskilled workers (many of these workers were employed in the lead-zinc mining and smelting complex) had significantly higher PbB values than children whose fathers had a higher level of education (P < 0.05 except for 'intermediate occupations'). 5. Discussion

The present study provides data on the lead concentrations in the venous blood of children living in a rural, an urban and a highly lead-polluted area of Greece. A major problem of lead exposure for the child population studied only exists in Lavrion. The distribution of PbB levels clearly exceed the PbB reference levels established by the C EC directive on the biological screening of the population for the lead (CEC, 1977). According to WHO recommendations (WHO, 1987) 98% of the general population should have PbB values < 20 /zg/dl (corresponding to a median value of ~ 10/zg/dl). In Lavrion the 98th percentile for the sample was 52.5/xg/dl with a median value of 21.0/zg/dl. On average, the highest PbB levels were found in those children attending the school closest to the lead smelter ( < 500 m). This finding is plaus ible since children usually live in the area sur-

Table 3 Blood lead levels (p,g/dl) of school children from Lavrion, Greece Group

n

GM

(95% CI)

P50

P90

P9s

Range

Boys Girls Total

274 240 514

23.4 19.9 21.7

(22.4-24.5) (18.9-20.9) (20.9-22.4)

22.8 19.0 21.0

38.9 38.8 21.0

53.5 49.9 52.5

9.4-79.8 7.4-59.3 7.4-79.8

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C. Maravelias et al. /Sci. Total Ent~ron. 158 (1994) 79-83

Table 4 Blood lead levels of school children from Lavrion in relation to the school attended School

Distance from the lead smelter

n

PbB(~g/dl) GM (95% CI)

81 115 192 113

30.94 (28.1-33.3) 20.06 (18.6-21.6) 20.98 (20.0-22.0) 19.36 (18.2-20.6)

(m) 3 1 2 4

< 500 900 1500 1500

rounding the school they attend and since it can be expected that the highest lead concentration in air, dust and soil are found in the vicinity of this school. Available data, concerning only soil lead content, have shown levels around 10000 p.p.m. for the school-yard closest to the plant and levels around 5000 p.p.m, for the other two school-yards (IGME, 1993). The finding that the boys of Lavrion have higher PbB levels than the girls corresponds to the wellknown fact that adult males, on average, have higher PbB levels than females (Brockhaus et al., 1983; Elinder et al., 1983). Although, some studies have failed to show a sex-related difference in children, there are several reports indicating that this difference already exists in childhood (Roels et al., 1980; Brockhaus et al., 1988). The above finding was not confirmed at the area of Koroni or at the area of Tavros, probably due to the small number of blood samples collected there (n = 157). Our results show also that children of unskilled workers - - most of them were working in the lead-zinc mining and smelting complex - - had, Table 5 Blood lead levels of school children from Lavrion in relation to the father's employment Father's employment Unskilled workers a Skilled workers Clerical workers Intermediate occupations Professional

n 148 166 52 19 12

PbB(~g/dl) GM (95% CI) 23.3 (21.8-24.8) 21.6 (20.5-22.8) 17.5 (15.0-19.4) 21.7 (18.4-25.8) 17.9 (14.9-21.5)

a Mainly workers of the Pb mining industrial complex.

on average, significantly higher PbB levels than other children. This finding is in agreement with several previous studies showing increased PbB levels in children from lead worker families and families of low socio-economic status (Elwood et al., 1977; Millar 1978; Zielhuis et al., 1979; Morton et al., 1982; Ewers et al., 1984, 1988; Brockhaus et al., 1988). It is assumed that the presence of a lead worker in the family is associated with substantial lead pollution of the home environment, which in turn, leads to a higher degree of lead exposure of family members, particularly young children (Rice et al., 1978). The negative consequences of lead exposure for children, especially for their psychometric intelligence and attentional performance, are well established. Considerable efforts have been made internationally to reduce the PbB levels in children living in polluted areas. Pollution control regulations and increased public awareness of the health hazards associated with living in a leadpolluted environment contributed to this. Immediately, after this study, actions were taken in order to decrease the children's exposure to lead in Lavrion. These included modification of the hygienic attitude of parents and children in addition to precautions that should be taken concerning the thorough cleaning of food (fruit, vegetables, etc.) and the house environment. They resuited, after 6 months, in a mean PbB value of 18.1 _+ 5 / z g / d l (data not shown). Studies like this one must be carried out all over Greece, in order to estimate the extent of the lead pollution problem in different areas and to take action, if necessary, to reduce the degree of lead exposure of the whole population and especially of the children. References Brockhaus, A., L. Freier, U. Ewers, E. Jermann and R. Dolgner, 1983. Levels of cadmium and lead in blood in relation to smoking, sex, occupation, and other factors in an adult population of the FRG. Int. Arch. Occup. Environ. Health, 52: 167-176. Brockhaus, A., W. Collet, R. Dolgner, R. Engelke, U. Ewers, I. Frier, E. Jermann, U. Kramer, N. Turfeid and G. Winneke, 1988. Exposure to lead and cadmium of children

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