This article was downloaded by: [New York University] On: 12 May 2015, At: 08:18 Publisher: Routledge Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Archives of Environmental Health: An International Journal Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/vzeh20
Dentine Lead and Child Intelligence in Taiwan Michael B. Rabinowitz Ph.D.
a b
, Jung-Der Wang M.D.
c a
& Wei-Tseun Soong M.D.
d
a
Department of Public Health National Taiwan , University College of Medicine , Taiwan b
Department of Neurology Boston , Harvard Medical School , Massachusetts, USA
c
Department of Internal Medicine , National Taiwan University College of Medicine , Taiwan d
Department of Psychiatry , National Taiwan University , Taiwan Published online: 03 Aug 2010.
To cite this article: Michael B. Rabinowitz Ph.D. , Jung-Der Wang M.D. & Wei-Tseun Soong M.D. (1991) Dentine Lead and Child Intelligence in Taiwan, Archives of Environmental Health: An International Journal, 46:6, 351-360, DOI: 10.1080/00039896.1991.9934402 To link to this article: http://dx.doi.org/10.1080/00039896.1991.9934402
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Downloaded by [New York University] at 08:18 12 May 2015
Dentine Lead and Child Intelligence in Taiwan
MICHAEL B. RABINOWITZ, Ph.D. Department of Public Health National Taiwan University College of Medicine and Harvard Medical School Department of Neurology Boston, Massachusetts JUNC-DERWANC, M.D. Department of Internal Medicine and Department of Public Health National Taiwan University College of Medicine WEI-TSEUN SOONG, M.D. Department of Psychiatry National Taiwan University
ABSTRACT. It is well known that lead is a developmental neurotoxin, but, because many factors influence a child’s development, a safe level of lead for children is still not clear. In this study, personal lead exposure was assessed. A total of 940deciduous teeth-mostly incisors-was collected from 764 children in grades 1-3 who attended 7 primary schools. Two of the primary schools were near smelters, 4 were in Taipei City, and 1 was located in a coastal village. Teachers were provided with a questionnaire about classroom performance, and 97% completed and returned the questionnaire to the laboratory. Parents were given a questionnaire about family background, pregnancy, and health history (92% returned). Dentine lead levels of shed incisors for children in Taipei City were higher than levels reported in Boston, i.e., mean (standard deviation) of 4.4 (3.5) versus 3.3 (2.5) &g, respectively (p < .001). The lead values were significantly higher in children who attended school near a smelter than in children who attended school in Taipei C i : 6.3 (3.3) (p < .001). The mean lead levels in children who attended school in a coastal village was 5.1 (2.8). The ranges for all schools overlapped, which indicated that there were multiple lead sources. Intelligencescores from Raven’s Colored Progressive Matrices Test were negatively correlated with lead levels, especially among girls and among children whose parents had less education. We adjusted for other risk factors-most notably parental education, which correlates inversely with lead levels-and found that the role of the lead term was lowered but not eliminated.
ENVIRONMENTAL POLLUTION from lead has long been recognized to cause adverse effects in children. A recent compilation of many studies on the correlation between child intelligence and lead exposure has demonstrated a robust dose-response relationship.’ This effect i s discernable, even at relatively low doses, in many countries (even after considering other confounding risk factors). The pediatric toxicity of lead is not limited to intelligence, but it is also linked with other deNovember/December 1991 [Vol. 46 (No. 6)]
velopmental processes.’ Recently, it was determined that children in Taiwan who attended a kindergarten near a lead recycling smelter had elevated blood lead levels and depressed I Q scores, even after other risk factors, e.g., parental education level^,^ were considered. The present study surpasses these past efforts in two ways. (1) Children who were studied had a wider range of lead exposure, i.e., those who lived near smelters 351
and those who lived in more urban and rural areas, thus extending downward the range of lead exposure studied. It was thought that this might reveal any safe threshold for effects of lead. (2) Also, the examination of human behavioral responses in another culture would enable a more full assessment of the generalizability of lead's toxic properties.
Downloaded by [New York University] at 08:18 12 May 2015
Subjects and methods Children were recruited into the study if they attended grades 1-3 in any of the 7 primary schools considered. These schools were chosen because they represented a range of potential lead exposures and served populations with broadly similar ethnic compositions. Some general characteristics of these schools are shown in Tables 1 and 2. Collectively, these schools contained 123 classrooms in grades 1-3, and they served approximately 4 600 pupils. The age of grade 1 children averaged 6.7 y (standard deviation = 0.4). Schools in remote areas that serve aboriginal children may have shown even lower lead exposure levels, but they were not included in this study because the social backgrounds of these children were much different. Comparisons of lead exposure and classroom behavior would not be possible if these children were compared with nonaboriginal chi Idren. Collection of samples. During the first week of October 1989, we visited the schools. The teachers at the 7 schools were informed of the purposes of our study, and they assisted in the collection of teeth and in the completion of rating forms for the children. Teeth that were shed during October, November, and December were collected. During these 3 mo, the children gave their teachers any teeth that were shed, and if the children had saved any teeth that had been shed earlier, the teachers also collected those. The teachers cornpleted a small form that identified the child, date the tooth was shed, and location the tooth had occupied in the child's mouth.
Table 1.-Schools
At least 1 tooth was received from each of the 764 children; 940 teeth were collected, but 78 were too decayed or too small to analyze. More than 1 tooth was submitted from 122 children. The distribution of tooth types and school grades are presented in Table 3. The 862 teeth with reported lead values are representative of only 692 children because 89 children each provided 2 usable teeth. In January 1990, blood lead measurements were o b tained from 60 children who attended 2 schools near smeltqs. The average blood lead level was 13.0 Ccgldl (SD = 4.41, and the median was 12 (range = 6-24). Tooth analysis. The tooth lead levels were determined in accordance with an earlier method used in B ~ s t o n . ~ All subsequent steps were completed in a room where there was controlled air flow, which was recirculated continuously by two HEPA air filters (model 100 Plus, Environmental Air Control, Albuquerque, NM). The tooth lead was determined in two portions of dentin that were taken from the zone presumably representative of postnatal deposition, i.e., between the pulp cavity and the neonatal line. Care was taken to avoid any areas that were decayed or areas within 3 mm of visible decay of reparative dentine. Specimens of postnatal dentine that weighed about 15 mg were o b tained from deciduous teeth that had the normal amount of resorption. Some teeth were too small or too decayed to use; these usually weighed less than 50 mg. The lead content was determined by anodic stripping voltammetry (model 3010A ESA, Bedford, MA). Procedural lead blanks were negligible and averaged 0.1 ng (SD = 3.4) per sample. The standard deviation, which is a useful estimate of the uncertainty of the blank, represents approximately 6% of the lead present. The long-term behavior of the system was monitored with a standard solution of lead-enriched calcium chloride. Lead in this solution and the aqueous working standards were determined by Professor William Manton (University of Texas), who used isotope dilu-
that Participated in Tooth Collection Incisor lead
School number Location
Potential exposure
Father attended some college (%)
old@
Number of cases
Mean
SD
3
47
6.1
2.9
0
24
5.1
2.8
t
I1
Lead smelter 1 km from school Control
2
Coastal village (fishing, resort)
3
Taipei City (administrative district)
City center
42
140
3.9
2.5
4
Urban
42
1 89
4.4
3.9
Urban
10
69
5.0
2.4
6
Taipei City (educational district) Taipei City (light industry) Taipei City (residential)
Urban fringe
7
Rural (farming, industry)
18 3
35 14
5.1 7.1
5.8 4.4
5
352
Rural (industrial)
Lead smelter 1.8 krn from school
Archives of Environmental Health
Table l.-Association
of Each Candidate Confounder With Lead and IQ
Candidate confounding variable 1. Sex (1
2. Grade
-
girl, 2
- boy)
Birth order Total number of siblings Number of adults at home Father's age now Father's education Father's job classification Mother's age Mother's education Mother's job classification Before birth, mother sick When pregnant, any medicine When pregnant, any bleeding Hormone to halt miscarriage When pregnant, any drinking When pregnant, ever drunk When pregnant, any tobacco Any pregnancy complication 20. Length of gestation 21. Weight of newborn 22. Delivery method 23. Presentation 24. Condition of newborn 25. Incubator 26. Jaundice 27. Any co-births 28. Any birth defects 29. Encephalitis 30. Meningitis 31. Fever more than 39 '-X 32. Head injury, not burns 33. Cerebral palsy 34. Seizures 35. Child's longest hospital stay 36. Child ever seriously ill 37. Handedness of child 38. In past year, moved home 39. Languages used by family 40. Age when tooth shed
Downloaded by [New York University] at 08:18 12 May 2015
3. 4. 5. 6. 7. 8. 9. 10. 11, 12. 13. 14. 15. 16. 17. 18. 19.
p value of variable IQ (CPM test) Pb (log) .4
.05
.05
.m
.06
.05
.m .15 .06
.m
.m .m
.005
.3
.m
.01 .4
.08 .4 .7
< 1 6
1 3
2
3 5
4
.4 .9
.m .m
.oooo
R' of variable in models of IQ (%I
.m
2 16 13 3
15*
.2 .9
.9
.7 .7
.6 .8 .4 .08 .6 .6 .m2 .1 .9 .8
.02 .9 .8
-
.18 .003 .9 .7 .8 .4
.5 .1 .7 .m1 .8
.7 .8 .9 .8 .3
.2
Archives of Environmental Health: An International Journal Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/vzeh20
Dentine Lead and Child Intelligence in Taiwan Michael B. Rabinowitz Ph.D.
a b
, Jung-Der Wang M.D.
c a
& Wei-Tseun Soong M.D.
d
a
Department of Public Health National Taiwan , University College of Medicine , Taiwan b
Department of Neurology Boston , Harvard Medical School , Massachusetts, USA
c
Department of Internal Medicine , National Taiwan University College of Medicine , Taiwan d
Department of Psychiatry , National Taiwan University , Taiwan Published online: 03 Aug 2010.
To cite this article: Michael B. Rabinowitz Ph.D. , Jung-Der Wang M.D. & Wei-Tseun Soong M.D. (1991) Dentine Lead and Child Intelligence in Taiwan, Archives of Environmental Health: An International Journal, 46:6, 351-360, DOI: 10.1080/00039896.1991.9934402 To link to this article: http://dx.doi.org/10.1080/00039896.1991.9934402
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Downloaded by [New York University] at 08:18 12 May 2015
Dentine Lead and Child Intelligence in Taiwan
MICHAEL B. RABINOWITZ, Ph.D. Department of Public Health National Taiwan University College of Medicine and Harvard Medical School Department of Neurology Boston, Massachusetts JUNC-DERWANC, M.D. Department of Internal Medicine and Department of Public Health National Taiwan University College of Medicine WEI-TSEUN SOONG, M.D. Department of Psychiatry National Taiwan University
ABSTRACT. It is well known that lead is a developmental neurotoxin, but, because many factors influence a child’s development, a safe level of lead for children is still not clear. In this study, personal lead exposure was assessed. A total of 940deciduous teeth-mostly incisors-was collected from 764 children in grades 1-3 who attended 7 primary schools. Two of the primary schools were near smelters, 4 were in Taipei City, and 1 was located in a coastal village. Teachers were provided with a questionnaire about classroom performance, and 97% completed and returned the questionnaire to the laboratory. Parents were given a questionnaire about family background, pregnancy, and health history (92% returned). Dentine lead levels of shed incisors for children in Taipei City were higher than levels reported in Boston, i.e., mean (standard deviation) of 4.4 (3.5) versus 3.3 (2.5) &g, respectively (p < .001). The lead values were significantly higher in children who attended school near a smelter than in children who attended school in Taipei C i : 6.3 (3.3) (p < .001). The mean lead levels in children who attended school in a coastal village was 5.1 (2.8). The ranges for all schools overlapped, which indicated that there were multiple lead sources. Intelligencescores from Raven’s Colored Progressive Matrices Test were negatively correlated with lead levels, especially among girls and among children whose parents had less education. We adjusted for other risk factors-most notably parental education, which correlates inversely with lead levels-and found that the role of the lead term was lowered but not eliminated.
ENVIRONMENTAL POLLUTION from lead has long been recognized to cause adverse effects in children. A recent compilation of many studies on the correlation between child intelligence and lead exposure has demonstrated a robust dose-response relationship.’ This effect i s discernable, even at relatively low doses, in many countries (even after considering other confounding risk factors). The pediatric toxicity of lead is not limited to intelligence, but it is also linked with other deNovember/December 1991 [Vol. 46 (No. 6)]
velopmental processes.’ Recently, it was determined that children in Taiwan who attended a kindergarten near a lead recycling smelter had elevated blood lead levels and depressed I Q scores, even after other risk factors, e.g., parental education level^,^ were considered. The present study surpasses these past efforts in two ways. (1) Children who were studied had a wider range of lead exposure, i.e., those who lived near smelters 351
and those who lived in more urban and rural areas, thus extending downward the range of lead exposure studied. It was thought that this might reveal any safe threshold for effects of lead. (2) Also, the examination of human behavioral responses in another culture would enable a more full assessment of the generalizability of lead's toxic properties.
Downloaded by [New York University] at 08:18 12 May 2015
Subjects and methods Children were recruited into the study if they attended grades 1-3 in any of the 7 primary schools considered. These schools were chosen because they represented a range of potential lead exposures and served populations with broadly similar ethnic compositions. Some general characteristics of these schools are shown in Tables 1 and 2. Collectively, these schools contained 123 classrooms in grades 1-3, and they served approximately 4 600 pupils. The age of grade 1 children averaged 6.7 y (standard deviation = 0.4). Schools in remote areas that serve aboriginal children may have shown even lower lead exposure levels, but they were not included in this study because the social backgrounds of these children were much different. Comparisons of lead exposure and classroom behavior would not be possible if these children were compared with nonaboriginal chi Idren. Collection of samples. During the first week of October 1989, we visited the schools. The teachers at the 7 schools were informed of the purposes of our study, and they assisted in the collection of teeth and in the completion of rating forms for the children. Teeth that were shed during October, November, and December were collected. During these 3 mo, the children gave their teachers any teeth that were shed, and if the children had saved any teeth that had been shed earlier, the teachers also collected those. The teachers cornpleted a small form that identified the child, date the tooth was shed, and location the tooth had occupied in the child's mouth.
Table 1.-Schools
At least 1 tooth was received from each of the 764 children; 940 teeth were collected, but 78 were too decayed or too small to analyze. More than 1 tooth was submitted from 122 children. The distribution of tooth types and school grades are presented in Table 3. The 862 teeth with reported lead values are representative of only 692 children because 89 children each provided 2 usable teeth. In January 1990, blood lead measurements were o b tained from 60 children who attended 2 schools near smeltqs. The average blood lead level was 13.0 Ccgldl (SD = 4.41, and the median was 12 (range = 6-24). Tooth analysis. The tooth lead levels were determined in accordance with an earlier method used in B ~ s t o n . ~ All subsequent steps were completed in a room where there was controlled air flow, which was recirculated continuously by two HEPA air filters (model 100 Plus, Environmental Air Control, Albuquerque, NM). The tooth lead was determined in two portions of dentin that were taken from the zone presumably representative of postnatal deposition, i.e., between the pulp cavity and the neonatal line. Care was taken to avoid any areas that were decayed or areas within 3 mm of visible decay of reparative dentine. Specimens of postnatal dentine that weighed about 15 mg were o b tained from deciduous teeth that had the normal amount of resorption. Some teeth were too small or too decayed to use; these usually weighed less than 50 mg. The lead content was determined by anodic stripping voltammetry (model 3010A ESA, Bedford, MA). Procedural lead blanks were negligible and averaged 0.1 ng (SD = 3.4) per sample. The standard deviation, which is a useful estimate of the uncertainty of the blank, represents approximately 6% of the lead present. The long-term behavior of the system was monitored with a standard solution of lead-enriched calcium chloride. Lead in this solution and the aqueous working standards were determined by Professor William Manton (University of Texas), who used isotope dilu-
that Participated in Tooth Collection Incisor lead
School number Location
Potential exposure
Father attended some college (%)
old@
Number of cases
Mean
SD
3
47
6.1
2.9
0
24
5.1
2.8
t
I1
Lead smelter 1 km from school Control
2
Coastal village (fishing, resort)
3
Taipei City (administrative district)
City center
42
140
3.9
2.5
4
Urban
42
1 89
4.4
3.9
Urban
10
69
5.0
2.4
6
Taipei City (educational district) Taipei City (light industry) Taipei City (residential)
Urban fringe
7
Rural (farming, industry)
18 3
35 14
5.1 7.1
5.8 4.4
5
352
Rural (industrial)
Lead smelter 1.8 krn from school
Archives of Environmental Health
Table l.-Association
of Each Candidate Confounder With Lead and IQ
Candidate confounding variable 1. Sex (1
2. Grade
-
girl, 2
- boy)
Birth order Total number of siblings Number of adults at home Father's age now Father's education Father's job classification Mother's age Mother's education Mother's job classification Before birth, mother sick When pregnant, any medicine When pregnant, any bleeding Hormone to halt miscarriage When pregnant, any drinking When pregnant, ever drunk When pregnant, any tobacco Any pregnancy complication 20. Length of gestation 21. Weight of newborn 22. Delivery method 23. Presentation 24. Condition of newborn 25. Incubator 26. Jaundice 27. Any co-births 28. Any birth defects 29. Encephalitis 30. Meningitis 31. Fever more than 39 '-X 32. Head injury, not burns 33. Cerebral palsy 34. Seizures 35. Child's longest hospital stay 36. Child ever seriously ill 37. Handedness of child 38. In past year, moved home 39. Languages used by family 40. Age when tooth shed
Downloaded by [New York University] at 08:18 12 May 2015
3. 4. 5. 6. 7. 8. 9. 10. 11, 12. 13. 14. 15. 16. 17. 18. 19.
p value of variable IQ (CPM test) Pb (log) .4
.05
.05
.m
.06
.05
.m .15 .06
.m
.m .m
.005
.3
.m
.01 .4
.08 .4 .7
< 1 6
1 3
2
3 5
4
.4 .9
.m .m
.oooo
R' of variable in models of IQ (%I
.m
2 16 13 3
15*
.2 .9
.9
.7 .7
.6 .8 .4 .08 .6 .6 .m2 .1 .9 .8
.02 .9 .8
-
.18 .003 .9 .7 .8 .4
.5 .1 .7 .m1 .8
.7 .8 .9 .8 .3
.2
