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Original article

Lead Exposure and Intellectual Function: Findings from Primary
School Children in Bangladesh

Haque M1, Faruquee MH2, Lahiry S3, Tasnim S4, Yasmin R5, Yasmin N6, Chaklader MA7

Abstract
Backgrounds: About 120 million people around the world are overexposed to lead which is neurotoxic and
99 percent of the most severely affected children are in the developing world including Bangladesh.
Methods and Materials: The present cross-sectional ecological study was carried out to explore the impact
of lead poisoning on the intelligence level among 84 primary school children of a school of Bangladesh,
aged between 8 and 14 years from September 2010 through January 2011. The research instrument was an
interviewer questionnaire, questionnaire for IQ test and assessment of blood lead level (inductively-coupled
plasma mass spectrometry with collision/reaction cells) of the study subjects after obtaining permission
from their parents and the school authority. Results: Data were cross-checked and frequency distribution and
association using chi-square test was accomplished. Background information depicted majority (69.1%) of
the children aged10-11 years (mean = 10.25 ±1.177 yrs), female (51.2%), parents having primary level of
education or below (73.8% in case of father and 77.4% in mother) and from lower socioeconomics (78.6%
earned BDT 10,000 or below per month). Among all, majority (56%) were found to be moron, 27.4% in bor-
derline, while 8.3% were imbecile with the same proportion with normal level. By their blood lead level.
Majority (70.2%) had blood lead level up to 10 microgram/dl and the rest (29.8%) had more than 10 micro-
gram/dl. Though no statistically significant association was found between IQ level of the children and their
blood lead level (p>0.05), the health problems found among the respondents as abdominal pain (53.57%),
impatience (14.29%), nausea (10.71%) and all other problems (loss of concentration to study, ear problem,
anorexia and loss of weight) amounting for 21.43% are suggestive of chronic lead poisoning. Conclusion:
Further studies in large scale with larger samples including comparative studies of inter-industrial areas have
been strongly recommended. 

Key words: Blood lead level; IQ level; children

1. Mahbuba Haque, Lecturer, Delta Medical College, Dhaka
2. M.H.Faruquee, Assistant Professor, Department of Public Health, State University of Bangladesh
3. Suman Lahiry, Assistant Professor, Institute of Health Economics, University of Dhaka
4. Saira Tasmin, Doctoral student, Department of Human Ecology,The University of Tokyo
5. Rabeya  Yasmin, Senior Lecturer, Department of Occupational & Environmental Health, Bangladesh

Institute of Health Sciences,
6. Nawzia Yasmin, Associate Professor, Department of Public Health, State University of Bangladesh
7. Mainul Alam Chaklader, Assistant Professor, Community Medicine, Bangladesh Medical College
Corresponds to: Mahbuba Haque, Lecturer, Delta Medical College, Dhaka

Introduction
Lead is neurotoxic, and young children are at partic-
ular risk for exposure

i
. Numerous studies indicate

that blood lead concentrations above 10?g per
deciliter (0.483 ?mol per liter) are associated with
adverse outcomes on measures of intellectual func-
tioning as well as with social and behavioral conduct
1,2,3

. Lead may impair brain development and have
harmful health effects even at lower levels, and there
is no known safe exposure level 

4
.

The World Health Organization estimates that 15-18

million children in developing countries are suffer-
ing from permanent brain damage due to lead poi-
soning. Hundreds of millions of children and preg-
nant women in practically all the developing coun-
tries including Bangladesh are exposed to elevated
levels of lead

5
. Lead poisoning may be acute (from

intense exposure of short duration) or chronic (from
repeated low-level exposure over a prolonged peri-
od), but the latter is much more common. Children
with developing physique are especially vulnerable
to chronic lead poisoning because of their rapidly
developing nervous systems that are particularly

Bangladesh Journal of Medical Science Vol. 11 No. 04 Oct’12

292



sensitive to the effects of lead
6
. There is no safety

level of lead for children
7
. High quantity of lead is

found in the environment as paints on the walls and
doors, the playground equipments and batteries

8,9
.

Intelligence testing as IQ (intelligence quotient) is
the score of an intelligence test

10
and it is expected

that average IQ among children in third world coun-
tries will increase if toxicity and malnutrition of var-
ious kinds get eradicated

11
.

With the aforesaid public health concern, the present
cross-sectional study was planned and conducted to
explore the impact of lead poisoning on the intelli-
gence of the environmentally lead-exposed primary
school children of Bangladesh.

Methodology
The present cross-sectional ecological study was
conducted among children in a purposively selected
school (Panpara Govt. Primary School) in an indus-
trial area (Rajfulbaria thana in Savar district) from
September 2010 through January 2011. The school
was selected owing to its close proximity to the
industries. Study population was children of class
III, IV and V. All the children of these classes who
met the selection criteria and who were present at
school during the data collection time (n = 84) were
taken for IQ test, blood collection and face to face
interview after obtaining permission from their par-
ents and the school authority. After aseptic precau-
tion blood was collected for lead level. Lead level in
whole blood was measured using inductively-cou-
pled plasma mass spectrometry with collision/reac-
tion cells (ICP-MS, Agilent 7500ce-Agilent tech-
nologies, Waldbronn, Germany).Whole blood was
digested with 60% Nitric acid (HNO3) in an oven for
4 hours at 140

0
C. Before analysis samples were

diluted with milliQ and filtered. Two commercial
certified reference materials (CRMs) for blood were
used for quality control (Seronorm™ Trace
Elements Whole Blood L-1, REF 201505; LOT
MR4206 and Seronorm™ Trace Elements Whole
Blood L-2, REF 210205; LOT 1003192). A struc-
tured questionnaire was developed; its first part was
designed to know the socio-economic condition
from their parents. The second portion was for par-
ticipants IQ test. Data was collected through face to
face interview by using a pre tested questionnaire.

The children who refused to participate in the study
and who were unable to provide information owing
to physical or mental illness were excluded. Data
were cross-checked and frequency distribution and
association using chi-square test was accomplished.
Before study ethical clearance was taken from
Panpara Govt. Primary School committee.
About instrument:

Findings
The socio-demographic background of the respon-
dents, the IQ score, the blood lead level and the
analyses are shown as follows.

Table I: Distribution of the children by age
(n=84)

Mean = 10.25 ±1.177 years

Majority 40.5% (n=34) of the children were ?10
years old, followed by 28.6% (n=24) who were 11
years old, while the lowest 2.4% (n=2) was of 14
years or older.  The mean age was found to be 10.25
±1.177 years.

Figure I: Distribution of the children by sex
(n=84)

Among all the study subjects, female were slightly
higher (51.2%) than the male children (48.8%).

Lead Exposure and Intellectual Function

293

Age of the 

respondents 

(in years) 

Frequency 

(n) 

Percentage 

(%) 

8 -10 52 61.0 
11-13 30 35.8 
≥14 2 2.4 
Total 84 100.0 



Figure II: Distribution of the children by their
father’s educational level (n=84)

Figure II shows the distribution of the children by
their fathers’ education. In majority of the cases
(41.7%), fathers of the subject were found to have
primary level of education. This was followed by
32.1% who were illiterate, 11.9% who had H.S.C
level of education, 10.7% who had S.S.C level, while
in case of only 3.6%, fathers were found to be grad-
uate.

Figure III: Distribution of the children by their
mother’s education (n=84)

Figure III shows the distribution of the children by
their mothers’ education. In majority of the cases
(39.3 %), mothers of the subject were found to have
primary level of education. This was followed by
38.1% who were found to be illiterate, 10.7% got
S.S.C level of education, 9.5% with H.S.C level,
while the lowest, i.e. 2.4% were graduate.

Table II: Distribution of respondents by monthly
family income (n =84)

Table II shows that out of all respondents’ parents,
53.6% had  monthly income less than BDT 5000,

25% with monthly income BDT 5000-10000, 11.9%
with monthly income BDT 10000-20000, while only
9.5% had monthly income more than BDT 20000. 

Figure IV: Distribution of the children by their
level of IQ (n=84)

The pie chart shows the distribution of the respon-
dents by their level of IQ. Among the total, majority
of the children (56%) were found to be moron,
27.4% in borderline, while 8.3% were imbecile with
the same proportion with normal level.

Figure V: Distribution of the children by their
blood lead level (n=84)

Figure V shows the distribution of the respondents
by their blood lead level. Majority of the children,
i.e. 70.2% had blood lead level up to 10 micro-
gram/dl and the rest (29.8%) had more than 10
microgram/dl.

Table II: Distribution of the children by IQ level
and level of blood lead (n=84)

Haque M, Faruquee MH, Lahiry S, Tasnim S, Yasmin R, Yasmin N, Chaklader MA

294

32.1

41.7

10.7 11.9

3.6
0

5

10

15

20

25

30

35

40

45

illiterate primary S.S.C H.S.C graduate

illiterate

primary

S.S.C

H.S.C

graduate

38.1 39.3

10.7 9.5

2.4

0

5

10

15

20

25

30

35

40

45

illiterate primary S.S.C H.S.C graduate

lmbecile(2
5-49), 8.3

moron(50-
69), 56

borderline
(70-

79), 27.4

Normal(70
-79), 8.3

Up to 10 
microgram/d

l,      70.2%

More than 
10 

microgram/d
l,      29.8%

Income range (BDT) Frequency (n) Percentage (%) 

<5000 45 53.6 
5000-10000 21 25 
10000-20000 10 11.9 
>20000 08 9.5 
Total 84 100.00% 



Table II shows that there is no statistically signifi-
cant association between IQ level of the children
and their blood lead level (p>0.05).

Table III shows that out of all children, 56 suffered
from different ailments. Among them, majority
(53.57%) was found to suffer from abdominal pain;
this was followed by impatience (14.29%) and nau-
sea (10.71%) while all other problems (loss of con-
centration to study, ear problem, anorexia and loss
of weight) amounted for 21.43% of the respondents. 

Table IV shows that 22(39.29%) of the respondents
were found to suffer from health problem(s) of any
kind for 2-3 months, 16(28.57%) for 6 months, fol-
lowed by 8(14. 29%) for 1 year, while only
10(17.86%) for more than 1 year.

Table V: Breast feeding of the respondents (n =
84)

Table V shows that All of the respondents were pro-
vided colostrums,12(14.3%)of the respondents did
not take milk after colostrums, Exclusive breast feed-
ing was completed by 72(85.71%) and up to 2 years
by 25(29.76%) of the respondents. 

Discussion
Most industrialized countries may have adequate
information about the environmental hazards as lead
poisoning status of the adults as well as children,
whereas such data are rare in developing countries
like Bangladesh. It is difficult to ascertain the sever-
ity of the problem, because there are very few stud-
ies which may reflect the actual situation of lead poi-
soning among the children of Bangladesh. It may be
mentioned here that childhood lead poisoning con-
tinues to be a major public health problem for certain
at-risk groups of children, and concerns remain over
the effects of lead on intellectual development in
infants and children 

12
.

The present cross-sectional study was conducted to
explore the impact of lead poisoning on the intelli-
gence among primary school children. Among 84
respondents, 43 were female and 41 were male. The
age ranged between 8 and 14 years. More than forty
percent of the children were 10 years old.  Regarding
age of respondents, the current study was found to
be very similar with the study done by Kaiser et al 

13

where they evaluated children at five primary
schools in Dhaka to determine blood lead (BPb) lev-
els, sources of environmental exposure, and poten-
tial risk factors for lead poisoning. Selected schools
represented a range of geographic and socioeconom-
ic strata. In a total of 779 students, 4-12 years of age
participated. It may be mentioned here that child-
hood lead poisoning continues to be a major public
health problem for certain at-risk groups of children,
and concerns remain over the effects of lead on intel-
lectual development in infants and children 

14
.

The Centre for Disease Control has set the standard
elevated blood lead level for adults to be 25 µg/dl of

Lead Exposure and Intellectual Function

295

χ2=0.262 p=0.967 

     IQ level Blood lead level Total 

Up to 10 

microgram/dl 

More than 10 

microgram/dl 

Imbecile (25-49) 5 2   7 
Moron (50-69) 32 15 47 
Borderline (70-79) 17 6 23 
Normal (90-109) 5 2 7 
Total 59 25 84 

Table V: Breast feeding of the respondents (n = 84) 
Breast feeding Frequency 

(n) 

Percentage 

(%) 

Non-exclusive Breast feeding 12 14.3 
Exclusive Breast feeding 72 85.7 

Table III: Distribution of health problems among respondents 

Health problems Frequency (n) Percentage (%) 

Anorexia 5 8.93 
Abdominal pain 30 53.57 
Nausea 6 10.71 
Weight loss 1 1.79 
Loss of patience  8 14.29 
Loss of 
concentration to 
study 

5 
8.93 

Ear problem 1 1.79 
Total 56 100.0 

Duration of 

health problem 

Frequenc

y (n) 

Percentage 

(%) 

2-3 months 22 39.29 
6 months 16 28.57 
1 year 8 14.29 
more than 1 years 10 17.86 
Total 56 100 

Table IV: Distribution of the respondents on
durationof their health problems (n = 56)



the whole blood. For children however, the number
is set much lower at 10 µg/dl of blood and in 2012
there were recommendations to reduce this to 5
(µg/dl)

15
Children are especially prone to the health

effects of lead and as a result, blood lead levels must
be set lower and closely monitored if contamination
is possible

16
. In the present study we found blood

level lead more than 5(µg/dl). 

In the present study the socio-economic status were
not so high, which were reflected by the respondents
monthly family income, father’s and mother’s edu-
cation and occupation, home material etc. More than
60 percent respondents, fathers and mother had pri-
mary level of education, SSC, HSC and graduate and
thirty-two percent were illiterate. Parent’s education
level is a factor to IQ level of the children

12,13
.

In the current study, majority (about 85.71%) of the
respondents had taken their mothers’ breast milk for
6 months. Numerous studies report that breastfeed-
ing is associated with higher scores on tests of neu-
rodevelopment and cognition in later life

17
, suggest-

ing that breast milk may impact early brain develop-
ment, with potentially important biological, medical
and social implications.

Regarding the IQ score, it was found that majority of
the children (about fifty-six percent) were moron
and about twenty-seven percent of the children were
in borderline. The rest, i.e. eight percent were imbe-
cile with the same proportion of normal level chil-
dren. In case of blood lead level seventy percent of
the children had blood lead level up to ten micro-
gram/ dl and thirty percent of children had blood

lead level more than ten microgram/ dl (highest 65
mg/dl and lowest 4 mg/dl). In a similar type of study
which was conducted on 1,333 children who partic-
ipated in seven international population-based longi-
tudinal cohort studies, followed from birth or infan-
cy until 5–10 years of age. The full-scale IQ score
was the primary outcome measure.  In that study it
was concluded that environmental lead exposure in
children who have maximal blood lead levels < 7.5
?g/dL is associated with intellectual deficits

18
.

In the present study, no significant association was
found in between IQ level and blood lead concentra-
tion of the respondents. Limitations of the study
include small sample size (only 84 children), limited
time and resources; each of which was a major con-
straint. The study was carried out only in one pri-
mary school in Bangladesh. Therefore, it may not
reveal the true picture of the country.

Conclusion and Recommendations
The present cross-sectional ecological study
revealed that 56% of the children under study were
found to be moron, 27.4% to be in borderline and
8.3% found as imbecile. Regarding lead level in
blood, 70.2% children had blood lead level up to 10
microgram/dl, while 29.8% had it more than 10
microgram/dl. Though no statistically significant
association was found between IQ level of the chil-
dren and their blood lead level, respondents were
found to suffer from health problems suggestive of
chronic lead poisoning. Therefore, further studies in
large scale with larger samples are strongly recom-
mended among children residing in industrial areas.

Haque M, Faruquee MH, Lahiry S, Tasnim S, Yasmin R, Yasmin N, Chaklader MA

296



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