| OBJECTIVE:At the end of last century,the prevalence rate of children lead poisoning in China came to 50%,went up to 85%even in some large cities or industrial areas. Lead poisoning can result in multi-systematic damages,especially intelligence development in children.General use of leaded gasoline and leaded paints,polluted air,water and food should take responsibility for children's lead poisoning. Children's lead poisoning,therefore,is not just a disease,but a social problem, which should be paid enough attention by governments and solved through cooperation among different departments.From 1997,China had used unleaded gasoline around the nation.Guangzhou is one of the first cities taking this execution. So a series of research have been carried to study the prevalence of children's lead poisoning in Guangzhou,evaluate the effects of unleaded gasoline,explore the preventive measures on children's lead poisoning and find the risk factors.METHODS:Two series of studyies were involved.1) The researchs on children's lead poisoning and relative factors.Stratified random sampling was used to sample one downtown,one suburb and one countryside first,and then 4 kindergartens and 4 primary schools were secondly sampled randomly among each district.Thirdly,2 classes in each grade were selected.Finally all individual samples were chosen on the principle of voluntary and consents from the monitors.The survey group consist of 2～13 years old students who resident in the district over at least 1 year.2 ml blood extraction,height,weight and one questionnaire(completed by parents) were applied. Blood lead level test by using ICP-MS(American thermoelectricity Group).Lead poisoning children were matched with 1:2 children of normal blood lead level to research influence on immunity and nerve behaviors by lead poisoning.2) Lead pollution paints research.There were 22 parks with children playgrounds in Guangzhou and all were taken as sampled parks.To select representative kindergartens,one downtown,one suburb and one countryside were sampled from the city by stratified sampling firstly.Then,20 kindergartens were sampled from each district by the same method.The tested subject included all kind of painting surfaces which might be touched when children are playing.An portable X-Ray Fluorescence Analyzer was employed to detect the lead contents of every paints. Additionally,28 peeled off paint fragments and 58 new paint samples available on the market are collected and tested by Flame Atomic Absorption Spectrum.Children's lead poisoning standard is 100μg/L(blood lead level),according to the standard of USCDC.Paint lead level is 0.5%(total lead),based on the standard of CPSA(Consumption Product Safety Act) and Indoor Decorating and Refurbishing Materials- Limit of Harmful Substances of Solvent Coatings for Wooden Ware(China).The assembled data were input twice by Epi data 5.21,analyzed with SPSS 15.0.The comparisons among the different groups of children's blood lead level were applied by t-test,χ~2-tests were used for rates comparison.Multi-linear regression,main effects and Logistic regressions were used in multi-factors of children's lead level analysis.Rank tests were used to compare the paint lead level.RESULTS: 2373 children completed the questionnaires and blood lead test,with 1233 males and 1140 females.1906 paint surfaces from 60 kindergartens and 22 parks were test for lead by an X-Ray Fluorescence Analyzer and 28 peeling paint fragments and 58 new paint samples available on the market were collected and tested by a Flame Atomic Absorption Spectrum.1.The average blood lead level(BLL) was 60.65μg/L with maximum of 330μg/L and minimum of 10μg/L.60 children(2.51%) were diagnosised with lead poisoning(BLL equal or more than 100μg/L).Among them,58 children were with mild lead poisoning(100μg/L≤blood lead level＜200μg/L),only 2 children with middle lead poisoning(200lag/L≤blood lead level＜450μg/L).2.The relations between blood lead levels and ages were analysised for children. The differences of BLLs among age groups were significant(malles F=3.078, P=0.009;females F=10.896,P=0.000).Boys had the lowest average BLLs of 60.51μg/L in 10-12 years old group while girl had the lowest average BLLs of 50.78μg/L in 12-14 years old group.But when Pearsonχ~2 test and linear correlative analysis were applied to lead poisoning rates by different age groups,lead poisoning prevalence did not show changing with age(the two significances more than 0.05).3.Males' average BLL was 63.49μg/L,higher than females'(57.58μg/L) (t=7.947,P＜0.001).Except 4～6 yrs group and 6～8 yrs group,males' blood lead level is higher than females' in every age group.But the lead poisoning rate in males(36 children,2.9%) was not higher significantly than in female(24 children,2.09%) (χ~2=1.594,P=0.207).4.715 suburb children had their blood lead tested and the average BLL was 62.58μg/L with 20(2.80%) diagnosised as lead poisoning.853 downtown children had their blood lead tested and the average BLL was 60.19μg/L with 21(2.46%) diagnosised as lead poisoning.805 countryside children had their blood lead tested and the average BLL was 62.58μg/L with 19(2.36%) diagnosised as lead poisoning. LSD tests were applied to compare the differences between two districs after Oneway ANOVA test.The average BLL in suburb children was higher significantly than in downtown children or countryside children.But the difference of average BLL between downtown children and countryside children was not significant.The Pearsonχ~2 test showed lead poisoning rate in suburb children was the highest.5.Children in suburb family with￥7000～￥8999/month income have the highest blood lead poisoning rate(5.9%),follown by those with￥3000～￥4999/month income family(3.8%) and those with￥1000～￥2999/month income family.While children grown in downtown family with￥7000～￥8999/month income show the highest blood lead poisoning rate(4.5%),children grown in downtown family with￥5000/month below income have similar blood lead poisoning rate,all a little higher than 3%.Children grown in country family with￥1000/month below income have the highest blood lead poisoning rate(6.1%), follown by those with￥1000～￥2999/month income family and those with￥7000～￥8999/month income family,both blood lead poisoning rate nearly to 3.0%.No significant differences in children blood lead prevalence description has been observed among different districts in terms of different income family,with all P＞0.05.6.Linear regression was conducted to analysis the relationship among children blood lead level(BLLs) and factors.Children whose mother had lower diploma would get higher BLLs.But children lived in bigger house or near the street with lower BLLs.Fifteen factors were analysised by binvariable logistic regression with lead poisoning as dependent variable.Mother's age and living near street were protective factors while living near gasoline station/bus stop was risk factor.When principal component analysis was conducted among 18 factors in questionnaire, seven principal components with eigenvalue more than 1 accounted for 60.217% total cumulative initial eigenvalues.Among them,the first and the second principal components contributed most.7.Linear regression was conducted to analysis the relationship between children blood lead level(BLLs) and stature/avoirdupois.BLLs' impact on stature or avoirdupois was not found in boys(stature:t=-0.223,P=0.823;avoirdupois: t=1.205,p=0.228).In girls,the impact on stature was not significant(t=0.556, P=0.578),but the impact on avoirdupois was significantly negative(t=-3.462, P=0.001)8.Fifty-night children from lead poisoning group and 117 children from control group had their IgG,IgA and IgM in serum tested.The mean IgG levels from lead poisoning group were higher than from control group no matter in boys or in girls (boy:Z=-4.090,P＜0.001;girl:Z=-3.676,P＜0.001).But the mean IgM and IgA levels from two groups were not found different significantly.9.Fourty-night children from lead poisoning group and 99 children from control group were tested with Puzzle Test and Benton Visual Retention Test.The success rates two groups were basically coherent.The fast reaction time and the mean reaction time,the slowest reaction times were predominant in control group. But no significant differences were found after Independent T Tests were carded out. The visual retention time in lead poisoning group was higher than in control group but the difference was not statistically significant.10.In Guangzhou,1906 paint surfaces from 655 targetted objects in 22 parks and 66 kingdergartens were tested for lead contents with an X-Ray Fluorescence Analyzer.The lead contents of paints were found with mean of 13992mg/kg and median of 1720mg/kg,and the unqualified rate was 37.5%.The unqualified paints were found in every park and kingdergarten.The mean and unqualified rate of lead content in park paints(2945mg/kg and 42.9%,respectively) were higher significantly(χ~2=43.989,P＜0.001)than in kingdergarten paints(1322mg/kg and 37.5%,respectively).11.All paints were sampled from 3 distfics,the paints from downtown with lead content median of 1849mg/kg,from suburb with lead content median of 851mg/kg, from countryside with lead content median of 1302mg/kg.The difference was significant when statistical test was performed aomong 3 districs and the mean of paints from countryside was higher significantly than from suburb.The ququalified rates were significantly different too,with downtomn the highest(42.1%),surbub (36.2%) the second and countryside the third(30.6%).12.All 1906 samples were divided into white,black,red,yellow,blue and green 6groups.There were samples with lead over 5000mg/kg in every group. Yellow paints had the highest lead contents with midian of 17500mg/kg and unqualified rate of 69.1%,followed by green,red,black and blue.White paints had the lowest lead contents with midian of 74mg/kg and unqualified rate of 6.7%.13.All 1906 samples came from furnitures,toys,walls and fences/window. Paints fences/window had the highest lead contents with midian of 7914mg/kg and unqualified rate of 55.9%,followed by toys with midia of 2681mg/kg and 42.5%, walls with midia of 245mg/kg and 32.7%.Furnitures had the lowest lead contents with midian of 60mg/kg and unqualified rate of 10.7%.When lead contents of 1906 samples were analysised according the base material,metal surfaces had the highest lead contents with midian of 10000mg/kg and unqualified rate of 59.7%,followed by plastic surfaces with midia of 1737 mg/kg and 35.4%,and concrete surfaces with midia of 1008 mg/kg and 32.8%.Wooden surfaces had the lowest lead contents with midian of 119mg/kg and unqualified rate of 12.1%.14.Lead contents were analysised according to their used years.Paints used in 1999-2001 had significantly lower mean lead content and no statistically significant differences were found in other used year groups.But when samples were classified by their appearances,the lead content in shelling paint was higher than in paint in good condition.The lead contents and qualified rates in two groups were tested with Wilcoxon Noparameter Test andχ~2 Test respectively and the differences were significant(Z=-7.725,P=0.001;χ~2=33.230,P=0.000).15.Total 28 shelling paints were sampled to test for lead content with Flame Atomic Absorption Spectroscopy.Among them,16(57.1%) had lead content more than 600 mg/kg,6(21.4%) more than 5000 mg/kg.Toys had the highest lead content among the three kinds of objects.Among them was a green paint sampled from a sliding board in a kindergarten,with lead content of 51800mg/kg(10 times of 5000 mg/kg or 83 times of 600 mg/kg).16.Total 58 new paints were sampled to test for lead content with Flame Atomic Absorption Spectroscopy.Among them,29(50.0%) had lead content more than 600 mg/kg,14(24.1%) more than 5000 mg/kg.When Chinese standard of soluble lead less than 90mg/kg were useed to evaluate the paint,32(55.2%) samples were unqualified.One of the red bakelite paint had the highest lead content of 153000 mg/kg that accounted for 15.3%of gross weight(255 times of 600 mg/kg). 58 paint samples came from 12 manufactories including 8 small local factories and 4 large national corporations.The paints produced by national corporations were with higher lead content(median of 1745mg/kg,unqualified rate of 73%) than by the local factories(median of 108mg/kg,unqualified rate of 73%)(Z=-2.468,P=0.014;χ~2=10.115,P=0.002).17.The price of new paint dependent on its brand and package.After converted into comparable price of Chinese dollar￥/kg,the new paints were fixed their prices from 10.83￥to 35￥every kilogram with mean of 17.47￥/kg.No statistically significant was found when correlation analysis was performed(r=-0.116,P=0.386).18.All 58 samples were divided into 8 colors including white,black,red,yellow, gray,blue,green and silver.The lead contents in green,yellow and red were very high,especially in green with all 5 samples over 5000mg/kg.black and blue. White,black and silver paints had lower lead contents and other color paints.19.New paints(wih total lead median of 1005mg/kg) had higher lead content than old paints(wih total lead median of 553 mg/kg).But the difference was not statistically significant(Z=0.470,P=0.638).The unqualified rates(≥5000 mg/kg) between new and old paints were not statistically significant(χ~2=0.078,P=0.779). These could conclude the lead contents were not changed in new or old paints.CONCLUSIONS:1.The lead poisoning in children had decreased sharply after phasing out of leaded gasoline in Guangzhou and among them most cases wereⅡ(100μg/L≤BLL＜200μg/L).But compared to the rate of lead poisoning,the blood lead levels in children dropped slowly.The blood lead levels were different between genders or among ages and areas.2.Though the lead poisoning rates of chilren were high in same family income groups,we did not find the children in families with low incomes would be more possible with lead poisoning.3.The children living near the streets with heavy traffic did not present higher BLLs than the children living far from the sreets and we can conclude the exhaust gas of vehicles are not the risk of lead poisoning.4.Lower average avoirdupois was found in girls with lead poisoning and higher average lgG level was higher in lead poisoning children than in normal children. Except that,we did not find significantly physiological changes in lead poisoning children. 5.The paint lead was found generally existed when we tested the parks and the kindergartens with an X-Ray Fluorescence Analyzer in Guangzhou.The paints which were used in downtown had the highest lead unqualified rate.The lead contents were high in yellow,green and red paints.The paints sampled from fences/window had the highest lead contents follewn by paints from toys.The paints used on motal surfaces had the highest lead content follown by paints used on plastic and concrete.The wooden surfaces were found with paints of the lowest lead contents.6.The new paints sampled from markets in Guangzhou were found with high lead contents.Green,yellow and red paints had high lead contents while white,black and silver had low lead content.The paints manufactured by national factories had higher lead contents than by local factories.No correlation was found between paints' prices and lead contents.7.Paint lead must be taken seriously as a risk factor for childern lead poisoning. But the lead limits in paints were not obeyed though they had been published for years in China.
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