Archs oral Bid. Vol. 36, No. 9, pp. 671673, 1991 Britain. All rights reserved
Copyright 0
Printed in Great
0003-9969/91 $3.00 + 0.00 1991 Pcrgamon Press plc
AGE AND GENDER INFLUENCE ON LEAD ACCIJMULATION IN ROOT DENTINE OF HUMAN PERMANENT TEETH K.
BERCOVITZ
and D.
LAIJFER
Department of Oral and Maxillofacial Surgery, Rambam Medical Center, Faculty of MedicineTechnion-Israel Institute of Technology, Haifa 31096, Israel (Accep!ed 12 March 1991) Sammarypermanent teeth of individuals aged 14-6Q yr from a non-occupationally exposed population in northern Israel were analysed for lead accumulation in a atomic absorption spectrophotometer graphite-furnace. A significant correlation was established between lead level and age. No gender correlat.ion was found. The results suggest that any study dealing with lead accumulation in different populations has to compare groups of the same age range, ignoring the sex of the individuals. Key words: dentine, lead, age, gender, teeth.
IIWRODUCI’ION
The lead level in teetlh is used as an indicator of lead exposure. The more polluted the area, the higher the level. In many countries children’s teeth have been used as indicators of lead pollution (Fosse and Berg-Justesen, 1978; Haavikko et al., 1984; Grobler et al., 1985; Needleman, Tuncay and Shapiro, 1972). In all these studies the children were in the same age distribution and naturally the age range is relatively narrow. The range of ages for adults, however, is very large-more than SlDyr. Thus, if age affects lead accumulation in teeth, comparison of mean values of lead level in different populations might give a misleading estimate of llcad exposure and accumulation if the ranges and means of ages were different. Stringer et al. (1974) found significant variations in lead concentration in lungs with age. In dense bones the correlation of lead accumulation and age is controversial. Some! have found an association (Barry, 1975; Drasch and Ott, 1988; Somervaille, Chettle and Scott, 1985; Steenhout, 1982), whereas Nusbaum et al. (196!$) found no correlation with age. In deciduous teeth, lthe lead concentration increases with the child’s age (Altshuller er al., 1962; Stewart, 1974). The same was demonstrated in the permanent teeth of adults (Strehlow and Kneip, 1969), although the number of samples was small. Each sample, however, consisted of several teeth. Further, no adequate statistical tests were applied to verify the significance of the age differences in lead levels in teeth. Later Al-Naimi, Edmonds and Fremlin (1980) showed the same result, but analysed only a very small volume of each whole tooth. Frank et al. (1990) found significantly higher lead levels in the dentine of young subjects (age l&29 yr) than in older ones (age 32-65 yr), but did not look at smaller age-range groups.
Another factor that might effect lead accumulation is gender. Lead levels in lungs (Stringer et al., 1974), salivary calculi (Strubel, Rzepka-Glinder and Grobeker, 1987) and dense bones (Nusbaum et al., 1965; Barry, 1975) have been found to be higher in males than in females. Our aim now was to determine if lead levels in teeth are age and gender related, and whether, therefore, comparisons can be made only between groups of the same sex and the same age range and average age. MATERIALS
AND METHODS
143 permanent teeth extracted from 54 men and 89 women living in urban areas of northern Israel were analysed for lead concentration by atomic absorption spectrophotometer graphite-furnace. None of the tooth donors was occupationally exposed to lead or worked in connection with road vehicles. All teeth were sound but either impacted or loose due to bone resorption. All except 15 were third molars. Teeth were stored at -5°C until analysis and then divided into five groups according to the age of donors. Tooth roots consisting of dentine, obtained by cutting off the crowns and removing the cement layer with a dental drill, were dried at 105°C overnight, wet ashed with concentrated nitric acid and diluted to 25 ml with deionized water as described by Bercovitz and Laufer (199la). Statistical comparisons were made using one-way ANOVA. All data were checked for normal distribution. RESULTS
Lead concentration increased significantly with the age of the donor (p c 0.05). The regression lines were: y = 0.43x-7.01, for males, r = 0.76, n = 52,
Abbreviation: ANOVA,
y = 0.30x4.25
analysis of variance 671
for females, r = 0.76, n = 89,
K. BERCOWTZ and D. LAUFE~Z
672
Table 1. Increase of lead accumulation in root dentine of sound teeth in correlation with the age of the male tooth donors Lead levels @g/g dry dentine) Age range (yr) M-20 21-30 31-40 41-50 51-60
min-max
n
1.03-4.71 1.41-10.02 2.1 l-13.25 3.98-10.86 12.21-36.89
13 20 8 4 7
XrtSE 1.82 f 2.90 f 6.69 f 7.56 f 21.24 rt
0.32’ 0.41P l.30b l.90b 3.73’
n = Number of individuals. Values with the same superscript letter-no significant difference between the groups (p > 0.05). Values with different superscript letters-significant difference between the groups (p < 0.05). mitt-max-minimum and maximum values.
but there were no significant differences in lead levels between the first two age groups of males (Table 1) nor between the third and the fourth age groups of both sexes (Tables 1 and 2). In all the age groups no gender correlation could be demonstrated. In each age group there was no difference in lead level between males and females in the non-o~upationally exposed population (p > 0.05) (Tables 1 and 2), though there was a difference in annual ambulation, as shown by the regression coefficients of 0.43 ~.tgfg for males and 0.30 rg/g for females. In addition to the teeth in Tables 1 and 2, three teeth from two men aged 26 and 30 yr and one woman aged 34 yr, who were exposed to lead at work showed lead levels of 13.23, 13.86 and 19.04 parts/106, respectively, levels which were significantly higher than the corresponding levels for their age. DISCUSSION
A si~ificant positive correlation was found between lead level and the donor’s age in a non-occupationally exposed population. Where no significant difference could be shown, it may be due to the small sample size. Lappalainen and Knuuttila (1979) claimed that lead concentration increases with the age, but the regression coefficients of three out of five districts were O-0.1 and the correlation coefficients (r*) were 0 and 0.01. In the fourth district b was 0.37, Table 2. Increase of lead accumulation in root dentine of sound teeth in correlation with the age of the female tooth donors Lead levels &g/g dry dentine) Age range (rr) 14-20 21-U) 314 41-50 51-60
X*SE 1.58 f 3.10 f 7.17 f 8.80 : 15.29 t
0.20d 0.348 1.16’ 1.09’ 2.27’
min-max
n
0.58-3.29 0.86-10.39 1.79-16.26 4.39-16.68 12.74-19.82
18 44 12 11 3
n = Number of individuals. Values with the same superscript letter-no significant difference between the groups 0, > 0.05). Values with dii%erent superscript letters-significant difference between the groups @ < 0.05). min-rnax-minimum and maximum values.
but r2 was only 0.03 and in the fifth district the regression coefficient was 0.37 with r2 = 0.44. A correlation with age was demonstrated by Khandekar, Raghunath and Mishra (1986), but the range of each age group was 15 yr and the results were not checked for significance. Steenhout and Pourtois (198 1) found that the lead content in teeth was significantly related to tooth age. This relationship was established in permanent teeth of children and adults in three different populations: rural, urban and industrial. Our results are based mainly on one type of tooth, so that the use of the donor’s age was satisfactory. Further, there are no significant differences in the lead level of different tooth types (Bercovitz and Laufer, 199lb). No significant differences were found between the lead levels in teeth from men and women in any particular age group in this population from northern Israel. Both sexes were exposed to the same environmental pollution and, as we assume there is no sex difference in the anatomy of the gastrointestinal tract or of the lungs, absorption should be the same in both males and females. The same result was obtained by Khandekar et al. (1986) and by Steenhout and Pourtois (1981) in rural and urban regions. In the industrial region there was a significant higher lead level in the teeth of men. This obse~ation was attributed to their jobs, which involved them working closer to factories. Our findings indicate that when comparing the lead exposure of different populations, which are not occupationally exposed, it is important to use groups of the same age ranges whereas gender is not an important factor. Whether sex influences lead accumulation in industrial regions or occupationally exposed populations, as Steenhout and Pourtois (1981) suggested, remains to be investigated. ~ck~owiedge~e~ts-We gratefully acknowledge the analytical support extended us by IMI Institute for Research and ~velopment of Israel Chemicals Ltd. The analytical work required for this study was performed by their Analytical Department.
REFERENCES
Al-Naimi T., Edmonds M. I. and Fremlin J. H. (1980) The distribution of lead in human teeth using charged particle activation analysis. Phys. Med. Biol. 25, 719-726. Altshuller L. F., Halak D. B., Landing B. H. and Kehoe A. R. (1962) Deciduous teeth as an index of body burden of lead. J. Pediatrics 60, 224-229. Barry P. S. 1. (1975) A comparison of concentration of lead in human tissues. Br. J. ind. Med. 32, 119-139. Bercovitz K. and Laufer D. (199la) Lead accumulation in permanent teeth of patients suffering from ulcers of the gastrointestinal tract. Sci. Tot. Emir. 101,229-234. Bercovitz K. and Laufer D. (1991b) Tooth type as indicator of exposure to lead of adults and children. Archs oral Biol. 35, 895-897. Drasch G. A. and Ott J. (1988) Lead in human bones. Investigations on an occupationally non-exposed population in southern Bavaria (F.R.G.) II. Children. Sci. Tot. Envir. 68. 61-69. Fosse G. and Berg-Justesen N.-P. (1978) Lead in deciduous teeth of Norwegian children. Arch. envrr. Hlth 33, 166-175.
Lead level in relation to age and sex Frank R. M., Sargrntird-Maier M. L., Turlot J. C. and Leroy M. J. F. (1990) Comparison of lead level in human permanent teeth from Strasbourg, Mexico City and rural zones of Alsace. J. dent. Res. 69, 90-93. Grobler S. R., Rossouw R. J. and Kotze D. (1985) Lead level in circumpulpal dentine of children from different geographic areas. Arch oral Biol. 30, 819-820. Haavikko D., Anttila A., Hele A. and Vuori E. (1984) Lead concentration of enamel and dentine of deciduous teeth of children from two Finnish towns. Arch. envir. Hlth 39, 78-84.
Khandekar R. N., Raghunath R. and Mishra U. C. (1986) Lead levels in teeth of an urban Indian population. Sci. Tot. Envir. 58, 231-236.
Lappalainen R. and Knuuttila M. (1979) The distribution and accumulation of Cd, Zn, Pb, Cu, Co, Ni, Mn and K in human teeth from five different geological areas of Finland. Archs oral Eliol. 24, 363-368. Needleman H. L., Tuncay 0. C. and Shapiro I. M. (1972) Lead levels in deciduous teeth of urban and suburban American children. Nature 235, 11l-l 12. Nusbaum R. E., Butt El. M., Gilmour T. C. and Didio S. L. (1965) Relation of air pollutants to trace metals in bone. Arch. envir. H&h 10, 227-232.
673
Somervaille L. J., Chettle D. R. and Scott M. C. (1985) In vivo measurement of lead in bone using X-ray fluorescence. Phys. Med. Biol. 30, 929-943. Steenhout A. (1982) Kinetics of lead storage in teeth and bones: an epidemiologic approach. Arch. enuir. Hlth 37, 224-23 1. Steenhout A. and Pourtois M. (1981) Lead accumulation in teeth as a function of age with different exposures. Br. J. ind. Med. 38, 297-303.
Stewart D. J. (1974) Teeth as indicators of exposure of children to lead. Archs Dis. Childn 49, 895-897. Strehlow C. D. and Kneip T. J. (1969) The distribution of lead and zinc in the human skeleton. Am. ind. Hyg. Ass. J. 30, 372-378.
Stringer C. A., Zingaro R. A., Creech B. and Kolar F. L. (1974) Lead concentration in human lung samples. Statistical analysis. Arch. envir. Hlth 29, 268-270. _ Strubel G.. Rzenka-Glinder V. and Grobecker K. H. (1987) Heavy metals’in human salivary calculi. Deterrnina~on of cadmium, lead and zinc in human salivary calculi by direct solid sampling atomic absorption spectrometry using Zeeman effect background correction. 2. analyt. Chem. 328, 382-385.
Copyright 0
Printed in Great
0003-9969/91 $3.00 + 0.00 1991 Pcrgamon Press plc
AGE AND GENDER INFLUENCE ON LEAD ACCIJMULATION IN ROOT DENTINE OF HUMAN PERMANENT TEETH K.
BERCOVITZ
and D.
LAIJFER
Department of Oral and Maxillofacial Surgery, Rambam Medical Center, Faculty of MedicineTechnion-Israel Institute of Technology, Haifa 31096, Israel (Accep!ed 12 March 1991) Sammarypermanent teeth of individuals aged 14-6Q yr from a non-occupationally exposed population in northern Israel were analysed for lead accumulation in a atomic absorption spectrophotometer graphite-furnace. A significant correlation was established between lead level and age. No gender correlat.ion was found. The results suggest that any study dealing with lead accumulation in different populations has to compare groups of the same age range, ignoring the sex of the individuals. Key words: dentine, lead, age, gender, teeth.
IIWRODUCI’ION
The lead level in teetlh is used as an indicator of lead exposure. The more polluted the area, the higher the level. In many countries children’s teeth have been used as indicators of lead pollution (Fosse and Berg-Justesen, 1978; Haavikko et al., 1984; Grobler et al., 1985; Needleman, Tuncay and Shapiro, 1972). In all these studies the children were in the same age distribution and naturally the age range is relatively narrow. The range of ages for adults, however, is very large-more than SlDyr. Thus, if age affects lead accumulation in teeth, comparison of mean values of lead level in different populations might give a misleading estimate of llcad exposure and accumulation if the ranges and means of ages were different. Stringer et al. (1974) found significant variations in lead concentration in lungs with age. In dense bones the correlation of lead accumulation and age is controversial. Some! have found an association (Barry, 1975; Drasch and Ott, 1988; Somervaille, Chettle and Scott, 1985; Steenhout, 1982), whereas Nusbaum et al. (196!$) found no correlation with age. In deciduous teeth, lthe lead concentration increases with the child’s age (Altshuller er al., 1962; Stewart, 1974). The same was demonstrated in the permanent teeth of adults (Strehlow and Kneip, 1969), although the number of samples was small. Each sample, however, consisted of several teeth. Further, no adequate statistical tests were applied to verify the significance of the age differences in lead levels in teeth. Later Al-Naimi, Edmonds and Fremlin (1980) showed the same result, but analysed only a very small volume of each whole tooth. Frank et al. (1990) found significantly higher lead levels in the dentine of young subjects (age l&29 yr) than in older ones (age 32-65 yr), but did not look at smaller age-range groups.
Another factor that might effect lead accumulation is gender. Lead levels in lungs (Stringer et al., 1974), salivary calculi (Strubel, Rzepka-Glinder and Grobeker, 1987) and dense bones (Nusbaum et al., 1965; Barry, 1975) have been found to be higher in males than in females. Our aim now was to determine if lead levels in teeth are age and gender related, and whether, therefore, comparisons can be made only between groups of the same sex and the same age range and average age. MATERIALS
AND METHODS
143 permanent teeth extracted from 54 men and 89 women living in urban areas of northern Israel were analysed for lead concentration by atomic absorption spectrophotometer graphite-furnace. None of the tooth donors was occupationally exposed to lead or worked in connection with road vehicles. All teeth were sound but either impacted or loose due to bone resorption. All except 15 were third molars. Teeth were stored at -5°C until analysis and then divided into five groups according to the age of donors. Tooth roots consisting of dentine, obtained by cutting off the crowns and removing the cement layer with a dental drill, were dried at 105°C overnight, wet ashed with concentrated nitric acid and diluted to 25 ml with deionized water as described by Bercovitz and Laufer (199la). Statistical comparisons were made using one-way ANOVA. All data were checked for normal distribution. RESULTS
Lead concentration increased significantly with the age of the donor (p c 0.05). The regression lines were: y = 0.43x-7.01, for males, r = 0.76, n = 52,
Abbreviation: ANOVA,
y = 0.30x4.25
analysis of variance 671
for females, r = 0.76, n = 89,
K. BERCOWTZ and D. LAUFE~Z
672
Table 1. Increase of lead accumulation in root dentine of sound teeth in correlation with the age of the male tooth donors Lead levels @g/g dry dentine) Age range (yr) M-20 21-30 31-40 41-50 51-60
min-max
n
1.03-4.71 1.41-10.02 2.1 l-13.25 3.98-10.86 12.21-36.89
13 20 8 4 7
XrtSE 1.82 f 2.90 f 6.69 f 7.56 f 21.24 rt
0.32’ 0.41P l.30b l.90b 3.73’
n = Number of individuals. Values with the same superscript letter-no significant difference between the groups (p > 0.05). Values with different superscript letters-significant difference between the groups (p < 0.05). mitt-max-minimum and maximum values.
but there were no significant differences in lead levels between the first two age groups of males (Table 1) nor between the third and the fourth age groups of both sexes (Tables 1 and 2). In all the age groups no gender correlation could be demonstrated. In each age group there was no difference in lead level between males and females in the non-o~upationally exposed population (p > 0.05) (Tables 1 and 2), though there was a difference in annual ambulation, as shown by the regression coefficients of 0.43 ~.tgfg for males and 0.30 rg/g for females. In addition to the teeth in Tables 1 and 2, three teeth from two men aged 26 and 30 yr and one woman aged 34 yr, who were exposed to lead at work showed lead levels of 13.23, 13.86 and 19.04 parts/106, respectively, levels which were significantly higher than the corresponding levels for their age. DISCUSSION
A si~ificant positive correlation was found between lead level and the donor’s age in a non-occupationally exposed population. Where no significant difference could be shown, it may be due to the small sample size. Lappalainen and Knuuttila (1979) claimed that lead concentration increases with the age, but the regression coefficients of three out of five districts were O-0.1 and the correlation coefficients (r*) were 0 and 0.01. In the fourth district b was 0.37, Table 2. Increase of lead accumulation in root dentine of sound teeth in correlation with the age of the female tooth donors Lead levels &g/g dry dentine) Age range (rr) 14-20 21-U) 314 41-50 51-60
X*SE 1.58 f 3.10 f 7.17 f 8.80 : 15.29 t
0.20d 0.348 1.16’ 1.09’ 2.27’
min-max
n
0.58-3.29 0.86-10.39 1.79-16.26 4.39-16.68 12.74-19.82
18 44 12 11 3
n = Number of individuals. Values with the same superscript letter-no significant difference between the groups 0, > 0.05). Values with dii%erent superscript letters-significant difference between the groups @ < 0.05). min-rnax-minimum and maximum values.
but r2 was only 0.03 and in the fifth district the regression coefficient was 0.37 with r2 = 0.44. A correlation with age was demonstrated by Khandekar, Raghunath and Mishra (1986), but the range of each age group was 15 yr and the results were not checked for significance. Steenhout and Pourtois (198 1) found that the lead content in teeth was significantly related to tooth age. This relationship was established in permanent teeth of children and adults in three different populations: rural, urban and industrial. Our results are based mainly on one type of tooth, so that the use of the donor’s age was satisfactory. Further, there are no significant differences in the lead level of different tooth types (Bercovitz and Laufer, 199lb). No significant differences were found between the lead levels in teeth from men and women in any particular age group in this population from northern Israel. Both sexes were exposed to the same environmental pollution and, as we assume there is no sex difference in the anatomy of the gastrointestinal tract or of the lungs, absorption should be the same in both males and females. The same result was obtained by Khandekar et al. (1986) and by Steenhout and Pourtois (1981) in rural and urban regions. In the industrial region there was a significant higher lead level in the teeth of men. This obse~ation was attributed to their jobs, which involved them working closer to factories. Our findings indicate that when comparing the lead exposure of different populations, which are not occupationally exposed, it is important to use groups of the same age ranges whereas gender is not an important factor. Whether sex influences lead accumulation in industrial regions or occupationally exposed populations, as Steenhout and Pourtois (1981) suggested, remains to be investigated. ~ck~owiedge~e~ts-We gratefully acknowledge the analytical support extended us by IMI Institute for Research and ~velopment of Israel Chemicals Ltd. The analytical work required for this study was performed by their Analytical Department.
REFERENCES
Al-Naimi T., Edmonds M. I. and Fremlin J. H. (1980) The distribution of lead in human teeth using charged particle activation analysis. Phys. Med. Biol. 25, 719-726. Altshuller L. F., Halak D. B., Landing B. H. and Kehoe A. R. (1962) Deciduous teeth as an index of body burden of lead. J. Pediatrics 60, 224-229. Barry P. S. 1. (1975) A comparison of concentration of lead in human tissues. Br. J. ind. Med. 32, 119-139. Bercovitz K. and Laufer D. (199la) Lead accumulation in permanent teeth of patients suffering from ulcers of the gastrointestinal tract. Sci. Tot. Emir. 101,229-234. Bercovitz K. and Laufer D. (1991b) Tooth type as indicator of exposure to lead of adults and children. Archs oral Biol. 35, 895-897. Drasch G. A. and Ott J. (1988) Lead in human bones. Investigations on an occupationally non-exposed population in southern Bavaria (F.R.G.) II. Children. Sci. Tot. Envir. 68. 61-69. Fosse G. and Berg-Justesen N.-P. (1978) Lead in deciduous teeth of Norwegian children. Arch. envrr. Hlth 33, 166-175.
Lead level in relation to age and sex Frank R. M., Sargrntird-Maier M. L., Turlot J. C. and Leroy M. J. F. (1990) Comparison of lead level in human permanent teeth from Strasbourg, Mexico City and rural zones of Alsace. J. dent. Res. 69, 90-93. Grobler S. R., Rossouw R. J. and Kotze D. (1985) Lead level in circumpulpal dentine of children from different geographic areas. Arch oral Biol. 30, 819-820. Haavikko D., Anttila A., Hele A. and Vuori E. (1984) Lead concentration of enamel and dentine of deciduous teeth of children from two Finnish towns. Arch. envir. Hlth 39, 78-84.
Khandekar R. N., Raghunath R. and Mishra U. C. (1986) Lead levels in teeth of an urban Indian population. Sci. Tot. Envir. 58, 231-236.
Lappalainen R. and Knuuttila M. (1979) The distribution and accumulation of Cd, Zn, Pb, Cu, Co, Ni, Mn and K in human teeth from five different geological areas of Finland. Archs oral Eliol. 24, 363-368. Needleman H. L., Tuncay 0. C. and Shapiro I. M. (1972) Lead levels in deciduous teeth of urban and suburban American children. Nature 235, 11l-l 12. Nusbaum R. E., Butt El. M., Gilmour T. C. and Didio S. L. (1965) Relation of air pollutants to trace metals in bone. Arch. envir. H&h 10, 227-232.
673
Somervaille L. J., Chettle D. R. and Scott M. C. (1985) In vivo measurement of lead in bone using X-ray fluorescence. Phys. Med. Biol. 30, 929-943. Steenhout A. (1982) Kinetics of lead storage in teeth and bones: an epidemiologic approach. Arch. enuir. Hlth 37, 224-23 1. Steenhout A. and Pourtois M. (1981) Lead accumulation in teeth as a function of age with different exposures. Br. J. ind. Med. 38, 297-303.
Stewart D. J. (1974) Teeth as indicators of exposure of children to lead. Archs Dis. Childn 49, 895-897. Strehlow C. D. and Kneip T. J. (1969) The distribution of lead and zinc in the human skeleton. Am. ind. Hyg. Ass. J. 30, 372-378.
Stringer C. A., Zingaro R. A., Creech B. and Kolar F. L. (1974) Lead concentration in human lung samples. Statistical analysis. Arch. envir. Hlth 29, 268-270. _ Strubel G.. Rzenka-Glinder V. and Grobecker K. H. (1987) Heavy metals’in human salivary calculi. Deterrnina~on of cadmium, lead and zinc in human salivary calculi by direct solid sampling atomic absorption spectrometry using Zeeman effect background correction. 2. analyt. Chem. 328, 382-385.
