Results of strategies for lead hazards management in a non-ferrous metallurgical area community.

Curseu, Daniela ; Sirbu, Dana ; Popa, Monica 等

Abstract: In this study 132 of subjects were reexamined in Copsa-Mica area after a sustained social marketing action and significantly lower blood lead levels were found. However, they were still much above the CDC guideline of 10[micro]g/dl. Consequently, the effects of lead exposure that already exist in childhood persist in young adults. High lead levels were also significantly associated with school abandonment. We conclude that long-term community actions are necessary in order to continue reducing blood lead levels.

Key words: pollution, lead, heavy metal, and environment.

1. INTRODUCTION

Environmental pollution in Copsa-Mica area has been a well-recognized long-lasting problem, for more than 60 years. The main source of concern is the non-ferrous metallurgical industry, the sole producer of zinc and electrolytic lead in the country. The lead values for the general population in Copsa-Mica exceeded the maximal allowable concentration (0.0007 mg/m3) sometimes up to 50 times before 1990 (Gurzau et al., 1995). In 1997 we reported a major health risk of lead exposure of children living in this area (Surdu et al., 1998). Those results were the starting point for the social marketing actions. A long-term community intervention including evaluation of the knowledge, attitudes, practices, messages sent to the population and feedback on the perception of messages, and making the community aware of the risks they are exposed to, took place next years. Moreover, technical measures for reduction of emissions from smelter were implemented.

The present study was conducted in order to evaluate the benefits of the intervention undertaken to reduce lead exposure and its effects on subjects anterior investigated, and furthermore, to determine whether there is an association of blood lead levels with children academic progress.

2. MATERIAL AND METHOD

To determine whether the lead expose and their effects persist, we reexamined 132 of 197 subjects who had initially been studied as schoolchildren in 1997. They were drawn from a total of 682 children attending primary school in two localities: Copsa-Mica town and Axente-Sever village. From old research records, and town records we located 177 subjects. Of these, 132 agreed to participate, and the remaining 45 declined. The mean age of the 132 subjects was 18.1 years; the mean length of time between the two examinations was 9 years. The subjects lived in the same area for entire period.

In the follow-up study, lead levels from venous blood (BPb) were measured using the same method as in 1997, atomic absorption spectrometry with graphite furnace facilities. All analyses were carried out under conditions involving internal and external quality control. Health outcomes consisted of blood pressure, hematological parameters (hematocrit, hemoglobin, and blood red cell count). We investigated also the association between lead levels in blood and failure of graduate from high school of young adults. Statistical analysis was performed by using STATA 5.0 software.

3. RESULTS AND DISCUSSION

In 1997 the statistical analysis of blood lead concentrations of the children showed values ranging from 16 to 48 [micro]g/dl, with a mean value and standard deviation of 28.12[+ or -]7.13 [micro]g/dl. None of the children had BPb below 10[micro]g/dl, the limit value according to the Centers for Disease Control criteria (CDC, 1991). Following the CDC classification into six classes of blood lead levels, all the investigated children, except three children 10 years old, ranged in the 3rd and 4th class (Fig.1).

The 132 retested subjects, after a sustained social marketing action, tended to present decreased BPb levels, the mean value (26.14 [+ or -]3.21 [micro]g/dl) being significantly lower (p=0.003) than in the precedent investigation. Thus, for 42 of the subjects BPb level dropped into an inferior CDC class. Though, the young adults remain to have an important exposure to lead. In the follow-up study we found levels between 10 and 39 [micro]g/dl (Table 1). The adult males have had higher BPb levels than females corresponding to the precedent study where the boys had higher BPb levels than girls. There are several reports indicating that this difference that already exists will be stressed after childhood period (Brockhaus et. al., 1988, Maravelias et. al., 1989).

An effect of lead on blood pressure was suggested more than 100 years ago, but until recently a number of studies involving lead workers and people in general population have shown a more consistent relationship between lead exposure and the increase in blood pressure or hypertension (Goyer, 1990). No threshold was found where the blood lead level was not significantly related to blood pressure across a range of 7 to 34 [micro]g/dl of blood lead. An interesting aspect of these studies is the large initial increments in blood pressure occurred at relatively low blood lead level, followed by blood pressure increments leveling of at higher blood lead levels.

In our study, the relationship between blood pressure and blood lead levels was examined in a multiple linear regression model. The blood lead biomarker was significantly associated with the diastolic blood pressure in both investigations (p=0.002; p=0.008) (Table 2). No statistically significant association was found between blood lead levels and systolic blood pressure.

Lead interferes with several enzymatic steps in the heme pathway. Recent data estimate a BPb threshold of 25[micro]g/dl for children (ATSDR, 1999). Our hematological findings are summarized in Table 3. Considering anemic those children who had at least two of the investigated hematological parameters below of the normal values, anemia in peripheral blood was discovered in half of cases (49.8 %) for the first examination and in 29.1% of cases for the second examination. Although BPb levels diminished slowly after social marketing action, prevalence of anemia was significantly lower after this intervention ([chi square]=13.27; p< 0.001).

Many authors stress the negative influence of environmental lead pollution on intellectual development. Figure 2 shows the relationship between blood lead levels and academic outcome of children from Copsa-Mica area. Subjects are distributed according to CDC blood lead level classes. No school records were found for two of 197 subjects tested in 1997. Ten of re-evaluated subjects are still attending high school and therefore not shown here.

In our study, the exposure to lead in childhood period was positive associated with diminished academic success. Two of the three subjects who were reported in 1997 to have BPb levels in 5th class did not attend the high school. In the follow-up study we found that the association between BPb levels and academic progress persists into young adulthood. Similar findings were reported in a follow-up study (Needleman et al., 1990) that correlated lead exposure with lower class standing; greater absenteeism; more reading disabilities, and deficits in vocabulary in young adults more than 10 years after childhood exposure.

[FIGURE 2 OMITTED]

4. CONCLUSIONS

The intervention plan implemented to reduce lead exposure in children living in Copsa-Mica area played an important role to diminish BPb levels even if still much above of the CDC guideline of 10[micro]g/dl. Improving the condition of homes and the personal hygiene such as washing hands and cutting fingernails short, house cleaning, and wash properly fruits and vegetables appear to be effective in reducing elevated BPb levels. However, the high blood lead levels found after the social marketing intervention provide convincing evidence that the late exposure to lead remain excessive. In addition, the significant correlations between BPb levels and anemia as well as high diastolic blood pressure persist. For this reason, this study reflects the necessity to maintain the local interventions (medical counseling, surveillance, health promotion and education) in order to continue reducing blood lead levels.

On the other hand, the findings of our study suggest that earlier exposure to lead may have an important and enduring effect on the school success of such children; the early indicators of lead burden and behavioral deficit are strong predictors of poor school outcome.

5. REFERENCES

ATSDR (1999) Case Studies in Environmental Medicine Lead Toxicity. Available from: http://www.atsdr.cdc.gov/HEC/CSEM/lead/physiologic_effects.html.

CDC. (1991). Preventing Lead Poisoning in Young Children: A Statement by the Centers for Disease Control. Atlanta, GA: Centers for Disease Control and Prevention. Available from: http://wonder.cdc.gov/wonder/prevguid/p0000029 /p0000029.asp#head001000000000000.

Brockhaus, A.; Collet, W.; Dolgner, R.; Engelke, R.; Ewers, U.; Freier, I.; Jermann, E.; Kramer, U.; Turfeld, N. & Winneke, G. (1988). Exposure to lead and cadmium of children living in different areas of North-West-Germany: results of biological monitoring studies, 1982-1986. Int. Arch. Occup. Environ. Health, 60: 211-222, ISSN 0340-0131.

Goyer, R. A (1990). Lead Toxicity: from Overt to Subclinical to Subtle Health Effects, Environ. Health Perspect., Vol. 86, Jun., 1990 (Jun., 1990), pp. 177-181, ISSN: 00916765.

Gurzau, E.S.; Niciu, E.; Surdu, S.; Bodor, E.; Costin, I.; Maier, A., (1995). Environmental health assessment of irritants and heavy metals in Transylvania, Romania. Centr. Eur. J. occup. Envir. Med. 1: 3-7, ISBN 978-1-4020-4844-9.

Maravelias, C.; Hatzakis, A; Katsouyanni, K.; Trichopoulos, D.; Koutselinis, A.; Ewers, U. & Brockhaus, A. (1989). Exposure to lead and cadmium of children living near a lead smelter at Lavrion, Greece. Sci.Total Environ., No. 84(Aug.1989), pp. 61-70, ISSN: 0048-9697

Needleman, H.L.; Schell, A.; Bellinger, D.; Leviton, A.& Allred, E.N. (1990). The long-term effects of exposure to low doses of lead in childhood. An 11-year follow-up report. N Engl J Med 322:63-88.

Surdu, S.; Gurzau, E.S.; Gurzau, A.; Curseu, D.; Faraian, D.; Bereczki, A.; Cristea, C.; Bodor, E.& Zeic, A., 1998. Risk Assessment /Communication in a Lead Contaminated area of Romania. Centr. Eur. J. of Pub. Health, Vol.6, No.2, pp. 123-126, ISSN 1210-7778.

Table 1. Difference of the BPb levels ([micro]g/dl) (* statistically
significant when p < 0.05)

 Tested in 1997 Retested in 2006

Variable Mean [+ or -] SD (Range) Mean [+ or -] SD (Range)

Copsa-Mica 29.6 [+ or -] 7.1 (16-48) 27.1 [+ or -] 4.5 (11-39)
Axente-Sever 24.0 [+ or -] 5.4 (18-32) 22.6 [+ or -] 5.3 (10-30)
Male 28.9 [+ or -] 7.8 (18-48) 27.1 [+ or -] 3.6 (13-39)
Female 26.8 [+ or -] 5.8 (16-36) 21.8 [+ or -] 4.2 (10-31)
Total cases 28.1 [+ or -] 7.1 (16-48) 26.1 [+ or -] 3.2 (10-39)

Variable p-value *

Copsa-Mica 0.0004
Axente-Sever 0.0227
Male 0.0137
Female 0.0000
Total cases 0.0030

Table 2. Correlation between diastolic blood pressure and BPb

Tested in 1997 Re-tested in 2006

Regression Regression
coefficient SE P-value coefficient SE p-value

0.044 0.013 0.002 0.041 0.014 0.008

Table 3. Laboratory signs of lead poisoning
(* 1st examination; ** 2nd examination)

 Blood red cell
 Hemoglobin Hematocrit count <4000000/
 < 13 g % < 36 % [mm.sup.3] Anemia

 N % N % N % N %

I * 86 43.6 73 37.1 85 43.2 98 49.8
II ** 52 9.4 38 29.8 32 24.3 39 29.1

Fig. 1. Comparison of blood lead levels among CDC classes.

 Tested in 1997 Re-tested in 2006

<10 [micro]g/dl 0 0
10-15 [micro]g/dl 0 13.6
15-20 [micro]g/dl 13.7 36.4
20-45 [micro]g/dl 84.8 50
45-70 [micro]g/dl 1.5 0
>70 [micro]g/dl 0 0

Note: Table made from bar graph.