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Screening of the gasoline lead load in school children in the Czech Republic
Toxicology Letters ELSEVIER
Toxicology Letters 88 (1996) 233-236
Screening of the gasoline lead load in school children in the Czech Republic L. Pelech, L. Malina, M. Cikrt, S. Janousek Nutionul Institute of Public He&h. Sroharovu 48, 100 42 Prugue, Czech Republic
Abstract
The determination of erythrocyte zinc protoporphyrin (ZZP) was implemented as an indirect method for assessing lead levels in the blood in the follow-up of Czech children regarding the lead load due to automobile traffic. Simultaneously, basic indicators of the red blood picture were studied. A screening study was conducted with 2668 school-age children residing permanently in three different regions of our country. The differences in basic hematological indicators, i.e. number of erythrocytes, hemoglobin content, hematocrit and red blood cell volume, like the differences in zinc protoporphyrin in the peripheral blood, did not confirm the initial hypothesis on the relatively greater load of the Czech child population due to lead from exhaust fumes of combustion motors. Also, no regional differences were observed. The differences found in the abovementioned indicators reflect the influence of an overall environmental pollution rather than that of a toxic effect of lead. Keywords:
School children; Gasoline lead; Zinc protoporphyrin;
1. Introduction An important lnoxa in human environment that threatens the population is lead. The child population is at particular risk because absorption in relation to body mass is greater in children than in adults. The toxicity of lead is greater for the child organism in view of the greater proportion of “biologically active” lead at the same concentrations of the noxum in the blood of children and adults, respectively. On the basis of data in the literature, it was assumed that in our present-day school-age child population living in a location at risk, a greater lead load
*Corresponding author.
Hematology
from exhaust fumes of ignition motors should be detectable [l-5].
2. Materials and methods In view of the difficulties connected with the sampling of venous blood from children for lead determination, we utilized the indirect method of determining the concentration of zinc-protoporphyrin (ZPP) in erythrocytes as an indicator of elevated blood levels of lead [6,7]. A single drop of capillary blood is needed for the determination of ZPP in erythrocytes by front-face fluorometry. Zinc-protoporphyringlobin levels are proportional to the intensity of fluorescence registered by fluorometry. For ex-
0378-4274/96/%15.00 0 1996 Elsevier Ireland Ltd. All rights reserved PII SO378-4274(96)03743-5
L. Pdrch et ui. I Tu.uicology Lerrers 88 (1996) 233-236
234
Table I Lead concentration in samples of airborne particulate matter determined by atomic absorption spectroscopy (arithmetical mean values per year) Region
Prague Control I Control II
Concentration of Pb (rg/m3) 1988
1989
1990
0.101 0.134 0.066
0.070 0.100 0.103
0.115 0.096 0.072
citation the so-called Soret band, i.e. 400-410 nm, was used and the transmitted fluorescence emitted in a band of around 590 nm was measured, corresponding to the concentration of ZPP
WI. Direct hematofluorometry as a screening method, especially when applied to washed erythrocytes, can detect loads at relatively low lead (Pb) blood levels in subjects without any symptoms at all. Simultaneously, it can detect sideropenic anemia in children absorbing lead under increased exposure situations. Moreover, the method meets requirements of the US Department of Health and Human Services concerning the economy and effectiveness of screening procedures based on the use of capillary blood [lo]. Prague, the capital city of the Czech Republic, has been chosen as an area with extremely heavy automobile traffic. The North Bohemian region was chosen as a region with an extremely polluted environment (control II). As a region with low exposure to automobile traffic, Central and Southern Bohemia has been selected (control I). The average values of lead concentrations in the atmosphere are presented in Table 1. In all, 2668 boys and girls aged 9-10 years have been examined. The basic clinical examination corresponded to a general preventive examination of a child. Capillary blood was taken from a finger of the left hand. The blood samples were analyzed using a Coulter Counter model FN automatic counter, a CE Hemoglobinmeter, and an AVIV model 206 hematofluorometer.
3. Results and discussion The differences in body height and proportions of children from the various locations revealed no effects of lead on somatic development. They rather reflect the influence of a permanent residence of children in a certain location. Of the hematological indicators studied, the highest values of hemoglobin values, red blood cells (RBC), and hematocrit volumes were found in children of control group I; the values in children from Prague were lower, and the lowest values were found in children of the North Bohemian Region (Fig. 1). The highest average values of ZPP were found in children from Northern Bohemia, followed by the group from Prague, while the lowest values were detected in children from Central and Southern Bohemia. Mutual differences between all three groups were statistically significant (P < 0.05). Of the children under study from Prague, individuals with the highest ZPP values (> 70 pmol/ mol haeme) were selected and invited to come along with their parents for a further examination in which venous blood was taken for the assessment of lead in blood. In one out of 21 children examined, atomic absorption spec-
Graph 1
Hb
ZPP
VOI
Hmt
Cd
Ci’,
/ IYII
I=lon/,,
,.
d/d
had
Fig. 1. Hematological parameters in the three evaluated groups of children from the control areas I and II and from the city of Prague. Hb, hemoglobin; Ery, erythrocytes; Vol, volume of erythrocytes; Hmt, hematoctit; ZPP, zinc protoporphyrin. pmoljhem, proportion of pmol of ZPP to the molar concentration of hemoglobin in SI units.
L. Pelech et al. I Toxicology Letters 88 (19%) 233-236
r--.~--
235
1
a Rhein-Ruhr Fig. 2. Reduction of lead emissions by automobile traffic in the period from 1975 to I989 in the Rhine-Ruhr district (adapted from
tometry (AAS) revealed a lead concentration of 13.39 j.q~/lOOml ‘blood. In all others, detected levels of lead did not exceed 10 &l 100 ml blood. From the results presented, the average values of the indicators under study in each group do not confirm the basic hypothesis of regional
-
70
-EC
-50
Fig. 3. Relationship between the petrol lead consumption in the USA in the period from 1976 to 1980 and the corresponding blood lead levels of the population (adapted from [ 121). BPb, blood lead level; PPb, petrol lead consumption.
differences in the lead load of the Czech child population due to exhaust fumes from ignition motors. Fig. 2 presents data from Germany on the decrease of lead emissions due to automobile traffic in the nineteen 1980s [ll]. The decreasing values of lead content in gasoline in the 1970s is closely correlated to the drop of lead load in the population of the USA [12] (Fig. 3). Our results are in good agreement with data supplied by the producers of gasoline in our country, showing a similar decreasing tendency in the amount of tetraethyl lead in gasoline (Table 2) as well as with the increased use of non-leaded gasoline. Therefore, we conclude that it is necessary to revise our initial hypothesis concerning the relatively high lead load in our population. The lead load of children due to exhaust fumes from ignition motors in the Czech Republic is rather nearer to the situation in Western European countries than to that in Eastern European countries. In the future, a further decrease in the amount of lead from exhaust fumes of ignition motors can be expected as a result of the gradual elimination of older models of private cars not constructed for the use of non-leaded gasoline. Following the example of all Western European countries, as a further step in
236
L. Pelech et al. I Toxicology Letters 88 (19%) 233-236
Table 2 Decrease of the concentration of lead in gasoline (mg/l) in the Czech Republic Type of gasoline
up to 1982
19831984
19851987
19881991
“Specil” 93 octane “Super” 98 octane
640 770
400 400
250 250
150 150
These Pb concentrations are the maximum limits allowed by the respective standards and were not exceeded.
favor of the use of non-leaded gasoline an apparent lower price should be recommended. Furthermore, the use of any motor vehicle without a catalyzer should be prohibited in smog situations.
Acknowledgments The study was supported by grant no. 9632191 of the Ministry of Health of the Czech Republic.
References [I] CDC (1991) Preventing Lead Poisoning in Young Children. Center of Disease Control, Atlanta, GA.
[2] Sayre, J.W. and Ernhart, C.B. (1992) Control of lead exposure in childhood. Are we doing it correctly? Am. J. Dis. Control 146 (1 l), 1278- 1281. [3] Winneke, G., Brockhaus, A., Ewers, U., Krlmer U. and Neuf, M. (1990) Results from the European multicenter study on lead neurotoxicity in children: implications for risk assessment. Neurotoxicol Teratol 12 (7), 1-7. [4] v. Miihlendahl, E. (1992) Bleibelastung bei Kindern. Sozialp;idiatrie 14 (IO), 783. [S] Rosen, J.F. (1992) Health effects of lead at low exposure levels. Am. J. Dis. Control 145 (1 I), 1278-1281. [6] Arnetz, B.B. and Nikolich, M.J. (1990) Modelling of environmental lead contributors to blood lead in humans. Int. Arch. Occup. Environ. Health 62, 397402. [7] Verschoor, M., Herber, R., Zielhuis, R. and Wybowo, A. (1987) Zincprotoporhyrin as an indicator of lead exposure: precision of zincprotoporphyrin measurements. Int. Arch. Occup. Environ. Health 59, 613-621. [S] Blumberg, W.E., Eisinger, J., Lamola, A.A. and Zuckermann, D.M. (1984) Principles and applications of hematofluorometry. J. Clin. Lab. Autom. 4 (I), 29-42. [9] Lamola, A.A., Joselow, M. and Yamana, T. (1975) Zinc protoporphyrin (ZZP): a simple sensitive fluorometric screening test for lead poisoning. Clin. Chem. 21 (I), 93-99. [IO] American Academy of Pediatrics Committee on Environmental Hazards and Committee on Accident and Poison Prevention (1987) Statement on childhood lead poisoning. Pediatrics 79 (6), 457-465. [I l] Pfeffer, H. (1991) Immissionen im Einflussbereich des Kraftfahrzeugverkehrs. Staub-Reinhalt. Luft 51, 63-69. [12] U.S. Environmental Protection Agency (1986) Air Quality Criteria for Lead, Vol. IV. USEPA, Research Triangle Park, NC
Toxicology Letters 88 (1996) 233-236
Screening of the gasoline lead load in school children in the Czech Republic L. Pelech, L. Malina, M. Cikrt, S. Janousek Nutionul Institute of Public He&h. Sroharovu 48, 100 42 Prugue, Czech Republic
Abstract
The determination of erythrocyte zinc protoporphyrin (ZZP) was implemented as an indirect method for assessing lead levels in the blood in the follow-up of Czech children regarding the lead load due to automobile traffic. Simultaneously, basic indicators of the red blood picture were studied. A screening study was conducted with 2668 school-age children residing permanently in three different regions of our country. The differences in basic hematological indicators, i.e. number of erythrocytes, hemoglobin content, hematocrit and red blood cell volume, like the differences in zinc protoporphyrin in the peripheral blood, did not confirm the initial hypothesis on the relatively greater load of the Czech child population due to lead from exhaust fumes of combustion motors. Also, no regional differences were observed. The differences found in the abovementioned indicators reflect the influence of an overall environmental pollution rather than that of a toxic effect of lead. Keywords:
School children; Gasoline lead; Zinc protoporphyrin;
1. Introduction An important lnoxa in human environment that threatens the population is lead. The child population is at particular risk because absorption in relation to body mass is greater in children than in adults. The toxicity of lead is greater for the child organism in view of the greater proportion of “biologically active” lead at the same concentrations of the noxum in the blood of children and adults, respectively. On the basis of data in the literature, it was assumed that in our present-day school-age child population living in a location at risk, a greater lead load
*Corresponding author.
Hematology
from exhaust fumes of ignition motors should be detectable [l-5].
2. Materials and methods In view of the difficulties connected with the sampling of venous blood from children for lead determination, we utilized the indirect method of determining the concentration of zinc-protoporphyrin (ZPP) in erythrocytes as an indicator of elevated blood levels of lead [6,7]. A single drop of capillary blood is needed for the determination of ZPP in erythrocytes by front-face fluorometry. Zinc-protoporphyringlobin levels are proportional to the intensity of fluorescence registered by fluorometry. For ex-
0378-4274/96/%15.00 0 1996 Elsevier Ireland Ltd. All rights reserved PII SO378-4274(96)03743-5
L. Pdrch et ui. I Tu.uicology Lerrers 88 (1996) 233-236
234
Table I Lead concentration in samples of airborne particulate matter determined by atomic absorption spectroscopy (arithmetical mean values per year) Region
Prague Control I Control II
Concentration of Pb (rg/m3) 1988
1989
1990
0.101 0.134 0.066
0.070 0.100 0.103
0.115 0.096 0.072
citation the so-called Soret band, i.e. 400-410 nm, was used and the transmitted fluorescence emitted in a band of around 590 nm was measured, corresponding to the concentration of ZPP
WI. Direct hematofluorometry as a screening method, especially when applied to washed erythrocytes, can detect loads at relatively low lead (Pb) blood levels in subjects without any symptoms at all. Simultaneously, it can detect sideropenic anemia in children absorbing lead under increased exposure situations. Moreover, the method meets requirements of the US Department of Health and Human Services concerning the economy and effectiveness of screening procedures based on the use of capillary blood [lo]. Prague, the capital city of the Czech Republic, has been chosen as an area with extremely heavy automobile traffic. The North Bohemian region was chosen as a region with an extremely polluted environment (control II). As a region with low exposure to automobile traffic, Central and Southern Bohemia has been selected (control I). The average values of lead concentrations in the atmosphere are presented in Table 1. In all, 2668 boys and girls aged 9-10 years have been examined. The basic clinical examination corresponded to a general preventive examination of a child. Capillary blood was taken from a finger of the left hand. The blood samples were analyzed using a Coulter Counter model FN automatic counter, a CE Hemoglobinmeter, and an AVIV model 206 hematofluorometer.
3. Results and discussion The differences in body height and proportions of children from the various locations revealed no effects of lead on somatic development. They rather reflect the influence of a permanent residence of children in a certain location. Of the hematological indicators studied, the highest values of hemoglobin values, red blood cells (RBC), and hematocrit volumes were found in children of control group I; the values in children from Prague were lower, and the lowest values were found in children of the North Bohemian Region (Fig. 1). The highest average values of ZPP were found in children from Northern Bohemia, followed by the group from Prague, while the lowest values were detected in children from Central and Southern Bohemia. Mutual differences between all three groups were statistically significant (P < 0.05). Of the children under study from Prague, individuals with the highest ZPP values (> 70 pmol/ mol haeme) were selected and invited to come along with their parents for a further examination in which venous blood was taken for the assessment of lead in blood. In one out of 21 children examined, atomic absorption spec-
Graph 1
Hb
ZPP
VOI
Hmt
Cd
Ci’,
/ IYII
I=lon/,,
,.
d/d
had
Fig. 1. Hematological parameters in the three evaluated groups of children from the control areas I and II and from the city of Prague. Hb, hemoglobin; Ery, erythrocytes; Vol, volume of erythrocytes; Hmt, hematoctit; ZPP, zinc protoporphyrin. pmoljhem, proportion of pmol of ZPP to the molar concentration of hemoglobin in SI units.
L. Pelech et al. I Toxicology Letters 88 (19%) 233-236
r--.~--
235
1
a Rhein-Ruhr Fig. 2. Reduction of lead emissions by automobile traffic in the period from 1975 to I989 in the Rhine-Ruhr district (adapted from
tometry (AAS) revealed a lead concentration of 13.39 j.q~/lOOml ‘blood. In all others, detected levels of lead did not exceed 10 &l 100 ml blood. From the results presented, the average values of the indicators under study in each group do not confirm the basic hypothesis of regional
-
70
-EC
-50
Fig. 3. Relationship between the petrol lead consumption in the USA in the period from 1976 to 1980 and the corresponding blood lead levels of the population (adapted from [ 121). BPb, blood lead level; PPb, petrol lead consumption.
differences in the lead load of the Czech child population due to exhaust fumes from ignition motors. Fig. 2 presents data from Germany on the decrease of lead emissions due to automobile traffic in the nineteen 1980s [ll]. The decreasing values of lead content in gasoline in the 1970s is closely correlated to the drop of lead load in the population of the USA [12] (Fig. 3). Our results are in good agreement with data supplied by the producers of gasoline in our country, showing a similar decreasing tendency in the amount of tetraethyl lead in gasoline (Table 2) as well as with the increased use of non-leaded gasoline. Therefore, we conclude that it is necessary to revise our initial hypothesis concerning the relatively high lead load in our population. The lead load of children due to exhaust fumes from ignition motors in the Czech Republic is rather nearer to the situation in Western European countries than to that in Eastern European countries. In the future, a further decrease in the amount of lead from exhaust fumes of ignition motors can be expected as a result of the gradual elimination of older models of private cars not constructed for the use of non-leaded gasoline. Following the example of all Western European countries, as a further step in
236
L. Pelech et al. I Toxicology Letters 88 (19%) 233-236
Table 2 Decrease of the concentration of lead in gasoline (mg/l) in the Czech Republic Type of gasoline
up to 1982
19831984
19851987
19881991
“Specil” 93 octane “Super” 98 octane
640 770
400 400
250 250
150 150
These Pb concentrations are the maximum limits allowed by the respective standards and were not exceeded.
favor of the use of non-leaded gasoline an apparent lower price should be recommended. Furthermore, the use of any motor vehicle without a catalyzer should be prohibited in smog situations.
Acknowledgments The study was supported by grant no. 9632191 of the Ministry of Health of the Czech Republic.
References [I] CDC (1991) Preventing Lead Poisoning in Young Children. Center of Disease Control, Atlanta, GA.
[2] Sayre, J.W. and Ernhart, C.B. (1992) Control of lead exposure in childhood. Are we doing it correctly? Am. J. Dis. Control 146 (1 l), 1278- 1281. [3] Winneke, G., Brockhaus, A., Ewers, U., Krlmer U. and Neuf, M. (1990) Results from the European multicenter study on lead neurotoxicity in children: implications for risk assessment. Neurotoxicol Teratol 12 (7), 1-7. [4] v. Miihlendahl, E. (1992) Bleibelastung bei Kindern. Sozialp;idiatrie 14 (IO), 783. [S] Rosen, J.F. (1992) Health effects of lead at low exposure levels. Am. J. Dis. Control 145 (1 I), 1278-1281. [6] Arnetz, B.B. and Nikolich, M.J. (1990) Modelling of environmental lead contributors to blood lead in humans. Int. Arch. Occup. Environ. Health 62, 397402. [7] Verschoor, M., Herber, R., Zielhuis, R. and Wybowo, A. (1987) Zincprotoporhyrin as an indicator of lead exposure: precision of zincprotoporphyrin measurements. Int. Arch. Occup. Environ. Health 59, 613-621. [S] Blumberg, W.E., Eisinger, J., Lamola, A.A. and Zuckermann, D.M. (1984) Principles and applications of hematofluorometry. J. Clin. Lab. Autom. 4 (I), 29-42. [9] Lamola, A.A., Joselow, M. and Yamana, T. (1975) Zinc protoporphyrin (ZZP): a simple sensitive fluorometric screening test for lead poisoning. Clin. Chem. 21 (I), 93-99. [IO] American Academy of Pediatrics Committee on Environmental Hazards and Committee on Accident and Poison Prevention (1987) Statement on childhood lead poisoning. Pediatrics 79 (6), 457-465. [I l] Pfeffer, H. (1991) Immissionen im Einflussbereich des Kraftfahrzeugverkehrs. Staub-Reinhalt. Luft 51, 63-69. [12] U.S. Environmental Protection Agency (1986) Air Quality Criteria for Lead, Vol. IV. USEPA, Research Triangle Park, NC