E l i f E r k a n , M . D . * / D e m e t B a ş d e m ir , M . D . * * / I ş ı l B a r l a n , M . D . * * T u r g a y İ s p i r , M . D . * * * / M ü j d a t B a ş a r a n , M . D . * * * D e p a r t m e n t o f P e d i a t r i c s , S c h o o l o f M e d i c i n e , U n i v e r s i t y o f A l b e r t E i n s t e i n , r i e w Y o r k , U S A . ** D e p a r t m e n t o f P e d i a t r i c s , S c h o o l o f M e d i c i n e , M a r m a r a U n i v e r s i t y , I s t a n b u l , T u r k e y . * * * D e p a r t m e n t o f M e d i c a l B i o l o g y ( D E T A M ) , S c h o o l o f M e d i c i n e , I s t a n b u l U n i v e r s i t y , I s t a n b u l , T u r k e y . A B S T R A C T
O b je c tiv e : Lead poisoning is one of the most common and preventable health problems today. Children are particularly susceptible to the toxic effect of lead. New data indicate significant adverse effects of lead exposure in children at blood levels previously believed to be safe. The majority of poisoned children show no signs and therefore remain undiagnosed and untreated. The aim of the study is to obtain data concerning the extent to which Turkish children are exposed to lead poisoning.
M e th o d s : One hundred and twenty children who w ork in the auto repair centers were recruited for the study group. O ne hundred and tw enty subjects who applied to M arm ara University Hospital outpatient clinics with upper respiratory com plaints made up the control group.
R e s u lts : The blood lead level of children who work in the car repair centers was 32.25±10.89 pg/dL, whereas this level was 22.95±6.69 pg/dL in the control group. This difference in the blood lead level was statistically significant (p<0.0001). C o n c lu s io n : It is suggested that lead exposure may be a serious problem in Istanbul. Considering the fact that even the control group
dem onstrated high blood lead level above the 'accepted level', larger studies including more subjects are needed in order to verify these results. We believe that the public should be inform ed of this im portant issue and preventive m easures should be taken.
K e y W o r d s : Lead intoxication, Public heath, Environm ent, Children.
IN T R O D U C T IO N
Lead poisining is one of the most com m on and preventable pediatric health problem today. Lead is ubiquitous in the hum an environm ent as a result of industrialization. Lead is a poison that affects virtually every system in the body (1-4). The adverse effects of lead on children and adults are su m m a rize d in Figure 1. It is particularly harmful to the developing brain and nervous system of fetuses and young children. Children are particularly susceptible to lead’s to xic effects. New d a ta in d ica te sig n ifica n t adverse effects of lead exposure in children at blood levels previously believed to be safe. It is established that a lead level as low as 10pg/dl may have deleterious effect on children (5,6). Blood lead levels between 10 and 14pg/dL are in
a border zone. The Agency for Toxic Substances and Disease Registry estim ated that in 1984, 17% of all Am erican preschool children had blood lead levels that exceeded 15pg/dl (7). The goal is to reduce children's blood lead levels below 10 pg/dL. C om m unity prevention activities should be triggered by blood lead levels of greater than 10 pg/dL.
The im pact of lead exposure on cognition in young children at BLLs > 10pg/dL has been am ply d e m o n stra te d and the literature is rem arkably consistent (8,9). On the other hand, most children with high blood lead levels have no signs. The w ast m ajority of cases therefore go undiagnosed and untreated .
25 years (mean age was 17 years). Two of the subjects were fem ale and the rest of the subjects were male (Table I). The study group was recruited from workers at car repair centers on the Asian side of Istanbul (Koşuyolu, Bostancı, Yukarı Dudullu) who had been exposed to lead containing gasoline and were more at risk for lead intoxication. 120 children and young adults were chosen for the control group. The ages were between 2-34 years (mean age was 19.5 years). There were 43 fem ales and 77 males in this group. The control group consisted of patients treated at Marmara University outpatient clinics for mild upper respiratory infection. None of the subjects had any known risk for high lead exposure by history.
There is no reliable data available regarding the extent of this hazardous intoxication among T urkish ch ild re n . In the study we aim to determ ine blood lead levels in a high risk group of children and com pare them with the children who does not have any known risk for lead intoxication.
M A T E R IA L S A N D M E T H O D S
S u b je c ts : One hundred and twenty children and young adults w ere recruited for the study group. The ages of the study group ranged between
9-1 5 0 u g /d L 1 0 0 u g /d L 5 0 u g /d L 4 0 u g /d L 3 0 u g /d L 2 0 u g /d L 1 0 p g /d L -► death ^ encephalopathy
P
nephropathy "► anemia -► colic-► hem oglobin synthesis ^ -► vita m in D m etabolism ^
_► nerve conduction velocity ^ IQ. hearing, growth 4 - > transplacental transfer
F ig .1 Observed effects of lead in children
M e th o d s : A blood sam ple of 5 ml_ was drawn from each patient. Sterile vacutainers containing EDTA were used to screen for blood lead levels. Tubes were centrifuged in the 1200 rpm for 15 minutes. Serum was separated and was stored in -35 °C. Blood lead level was determ ined by adding m etilisobutiketone (MIBK) to the serum of each subject as organic solvent and burning the sam ples in the graphite furnace. Standard lead and then am m onium pyrollidine ditiolcarbonat (APOC) was added to the blood samples. Atomic absorbtion was used to reduce Pb++ to Pb. The am ount that was absorbed by the lead molecule was determ ined by spectrophotom etry (1). These values w ere de te rm in e d as pg/dL after com parison with the standard curve.
T a b l e I. Characteristics of the study and the control groups.
Study Group (n:120) Control Group (n:120)
Mean age (yr) 17.12 19.25
Minimum age (yr) 9 2
Maximum age (yr) 25 34
Gender (M/F) 118/2 77/43
T a b l e II. Blood lead levels in the study and the control groups.
Study Group (n:120) Control Group (n:120)
Mean blood lead level (pg/dl) 32.25 23.29
Standard devitlon 0.99 0.61
Minimum blood lead level 16.2 12.3
Maximum blood lead level 54.3 42.6
O
o
Study Group
Control Group
Blood lead levels in the study and control groups.
R ESU LTS
The blood lead level was 32.25±10.89 pg/dL in the study group. This level was 22.95±6.69 pg/dL (Table II, Fig 2) in the control group. Mann W hitney U test was used as a statistical test to compare the results between the two groups. The d iffe re n ce betw een th e se tw o groups showed statistical significance (p<0.0001). The difference between the blood lead level based on the gender of the subject was not significant (p>0.05).
D IS C U S S IO N
The results of our study showed a significant increase in blood lead levels in children who work in autom obile repair centers in Istanbul. BLLs of the control group, although significantly lower than those of the study group were still high (>10pg/dL). None of these subjects showed any clinical signs of lead poisoning. A recent study conducted in Rochester, New York showed that variables a ssociated w ith increased risk of elevated BLLs in children were living within the city, in older housing of lower housing value, in areas of higher population density, their families showed higher rates of poverty, and there was
lower percent of high school graduates and lower rates of o w n e r o ccu p ie d housing (11). Presum ably, living in Istanbul involves num erous risk factos, including air pollution through lead containing gasoline, population density, older and inadequate housing and poverty.
The first study concerning blood lead levels in Turkey was conducted by G uray et al in 1966 (2). In this study blood and urine lead levels were determ ined in 87 high risk susbjects and the lead level in the air was also determ ined. It was shown that blood and urine lead levels were significantly elevated in the high risk subjects who worked in the environm ent w here the lead level in the air was also elevated. In a study conducted in Ankara which included 619 subjects (2-80 years), the geom etric mean of blood levels of children was found to be 16.95 pg/dL w hereas it was 8.39 m g/dL in the adult subjects (13). In 1990 in Mersin, w hilst the blood levels w ere between 15.58 pg/dL and 28.36 pg/dL in the high risk subjects, this level was only 7.26 pg/dL in the normal population (14). G oker showed that in 201 healthy children (6 m onths - 17 yr) in Istanbul, the mean blood lead level was 5.55 pg/dL and in 8.5 % of these children blood lead level was above 10 pg/dL (15).
In our study the fact that none of the subjects in the control group had a BLL<10 pg/dL raises the possibility of contam ination of the specimens. The ubiquty of lead in the environm ent adds to these concerns. To lower this possibility, we used venous blood sam pling which is a preferred method because it has a less likelyhood of contam ination com pared to blood collected by fin g e rstick. In a ddition , venous specim ens provide a la rg e r volum e fo r analysis than capillary specim ens which also lowers the risk of false positive test results. Athough we used sterile vacutainers for blood sampling, because blood sam pling was done in the automobile repair centers, the lead contam ination through air is still a possibility.
The analytical technique that we used was atomic absorption spectroscopy with graphite furnace which is capable of achieving detection limits of 2-5 pg/dL. This technique is considered as one of the best techniques for blood lead determ ination.
Two hundred and forty subjects from a certain region of Istanbul were recruited for our study. In order to have a better understanding of the dim ensions of this problem in Turkey, studies with larger num ber of subjects should be carried out and testing and treating children for lead exp o su re m ust be carried out in co o p e ra tio n w ith pub lic health program s to ensure environm ental investigation, transitional lead-safe housing assistance, and follow-up for individual cases.
In theory, prim ary prevention has always been the goal of childhood lead poisining prevention program s (16). With the prevention programs, the percentage of US children of 1 to 5 years of age with blood lead levels > 10 pg/dL has decreased from 88.2% to 4.4% (17,18). In practice, how ever, m ost program s focus exclusively on secondary prevention, dealing with children w ho have already been poisioned. As program s shift the em phasis to prim ary prevention, their efforts must be designed to s y s te m a tica lly id e n tify and rem ediate environm ental sources of lead. The shift from case m a n a g e m e n t to com m unity-level intervention will require a fundamental shift in perspective. The focus must shift from the individual child to the population of children at
risk and the environm ent in which they live. This prelim inary study allowed us to know that lead poisining could be a major public health problem in Istanbul. G overnm ent, like the medical community, should focus its efforts on children who are most at risk. To do this, more data about the prevalence of elevated BLLs in specific com m unities are needed. A better understanding of the distribution of lead in the environment would allow more efficient screening efforts.
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