PROJECT
LEAD-FREE: A STUDY OF LEAD POISONING IN MAJOR INDIAN CITIES
Screening
Conducted by The George Foundation for
Determining Blood Lead Levels in Urban Population
Abstract
Prior
to this undertaking, there has been no well-documented wide study of
the blood lead levels in India. Though some studies in pockets were
conducted previously, the available data do not reflect a true scenario
of the lead poisoning problem in the country, especially in urban environments.
The George Foundation initiated the first major study, Project Lead-Free,
in 1997 to screen 22,000 children and adults in 7 major Indian cities.
Results of the study indicate elevated levels of blood lead of over
10 µg/dL in a majority of children tested for this study. Future population-based
studies will be able to confirm whether these results are representative
of Indian cities as a whole.
Introduction
Lead
(Pb) and some of its chemical compounds are virtually ubiquitous in
the environment. Lead can now be found in air, drinking water, as well
as in soil and various food items. The possibility of Pb exposure in
humans is therefore of great significance from the health point of view.
Lead does not spare any organ in the body and is not known to serve
any necessary biological function. The presence of blood lead has always
been considered a sign of environmental pollution, whether it originates
from general or occupational environment.
While
lead poisoning is one of the major environmental disease in the world,
its impact on the Indian population is not fully understood. Scientific
studies conducted in the US and other countries have uncovered that
lead poisoning and iron deficiency anemia are problems of major proportions
in large cities throughout the world and more so in developing countries
where there are no (or few) environmental regulations. This paper describes
the Project Lead-Free study in India and its conclusions.
Objectives
The
objectives of Project Lead-Free were as follows:
1. To
determine the extent of lead poisoning in large and moderate size
Indian cities that are representative of the urban population in India.
Toward this primary goal, children between one and twelve years of
age, pregnant women, and emergency referrals from doctors and hospitals
were targeted for the study.
2. To
educate the community on the health problems associated with elevated
lead levels and iron-deficiency anemia, the paths of lead exposure
in their environment, and the ways by which they could protect their
families from lead exposure. This would be achieved through pamphlets,
newspaper advertisements, lectures at schools and community centers,
and through radio and television.
3. To
educate people on the need for a balanced diet, which is rich in iron,
to overcome anemia and to help prevent lead poisoning.
4. To
collect hard data on the problem of lead poisoning, its sources and
pathways in India for a subsequent nationwide program for prevention
and treatment.
Sample
Selection
In
order to achieve the above objectives, screening was done mostly in
the urban areas of Bangalore, Calcutta, Mumbai, Delhi, Chennai, Hyderabad
and Vellore. Most of the cities selected for the study have high-density
population where leaded petrol has contributed to environmental lead.
The study was coordinated by the Department of Biochemistry & Biophysics
of St. John’s National Academy of Health Sciences, Bangalore, and conducted
in conformity with the protocols established by the US Centers for Disease
Control and Prevention (CDC). In order to obtain good data of lead toxicity
in various parts of India, large samples were taken from several clinics
selected in each of the cities. Within the city, clinics and schools
were chosen to provide samples of economic variations. Apart from this,
heavy and low-density vehicular traffic was also considered while selecting
the samples.
Subjects
under following categories were selected for the study, considering
the large population of India and wide variations in the ethnic and
cultural backgrounds.
* Pre-school
children and toddlers in play homes and kindergarten centers. This
was achieved with the help of primary health workers.
* Slum
children and their parents in urban areas identified with the help
of Karnataka State Council for Child Welfare, Bangalore.
* School
children from low-income group areas. This was done by writing to
the heads of schools for voluntary participation of their students
with prior permission from parents.
* Pregnant
women attending antenatal clinics in hospitals and clinics that participated
in the study.
* High
risk adults such as those working in soldering units, battery and
paint industry, traffic policemen, garage workers etc.
Subjects
were selected on a random basis, and their willingness to participate
was confirmed prior to their tests. Since the entire project involved
participation of subjects on a voluntary basis, clinic representatives
in all cities had to motivate the public through briefing on the health
effects of lead. Efforts were also made through mass media to educate
the general public, as most of the population in India is ignorant about
the ill effects of lead in their environment. Information about the
family, location of residence, type of work, diet and other relevant
facts were also obtained prior to screening. The data were used for
further analysis in arriving at the probable sources of lead.
Methodology
Screening
methodology adopted included evaluation of Zinc Protoporphyrin (ZnPP)
and blood lead levels.
Determination
of ZnPP
From
1972-1991, ZnPP was the primary screening test recommended by the US
Centers for Disease Control and Prevention (CDC) for childhood lead
poisoning in the US. Only those with high ZnPP levels were further tested
for blood lead levels. Initial screening for ZnPP was adopted in Project
Lead-Free, keeping in mind the large numbers of people who would require
screening and the costs associated with conducting blood lead screening
directly. Haematoflurometer (Front Surface Flurometry), a portable device
dedicated to ZnPP analysis, was used in the screening. Fresh blood samples
were used at all times unless otherwise collected using disposable syringes
with heparin as an anticoagulant. The instrument was calibrated on the
day of use with controls supplied by the manufacturer.
In
most cases where ZnPP was higher than 35 µg/dL, oral iron folic acid
tablets were distributed to compensate any iron deficiency anemia. Further
follow-up of these treated cases of high ZnPP was conducted. In cases
where ZnPP still remained higher than 35 µg/dL after 3 months, blood
samples were again obtained and lead was determined using the lead analyzer.
Blood
Lead Determination with the Help of Anodic Stripping Voltammetry
Blood
lead was analyzed using 3010B ESA Lead Analyzer. Capillary tubes were
used for the collection of 100 µl of blood samples from fingertips blood,
which was transferred to the meta exchange reagent and mixed well for
the estimation of blood lead levels 24 hours after mixing.
In
all cases where capillary blood lead levels were higher than 40 µg/dL,
repeat estimation of lead with venous blood was carried out as per the
suggested protocol of CDC. The 3010B ESA lead analyzer was calibrated
on all days of its use with the calibrators supplied by the manufacturer
and by using controls. The instrument was kept on around the clock.
In a few samples, blood lead was determined using Atomic Absorption
Spectrophotometry also, and the values were confirmed to be comparable.
With the operating range of 1-100 µg/dL lead and a detection limit of
1 µg/dL, the methodology adopted was sensitive with a precision of 10%
RSD at 10 µg/dL. With a short analysis time of 90 seconds, the method
adopted for the estimation of blood lead proved to be reliable.
In
addition to screening for blood lead of those with ZnPP levels of 35
µg/dL or higher, 2,031 subjects were screened randomly irrespective
of their ZnPP results.
Results
and Discussion
A
total of 21,476 samples (14,667 children below the age of 12, and 6,809
older children and adults) were tested for ZnPP. 28.9% of the children
and 24.2% of the adults showed ZnPP levels above 35 µg/dL. The percentage
of children with ZnPP levels above 35 µg/dL ranged from a low of 27.6%
in Chennai to 67.7% in Hyderabad, while the largest sample of 12,173
children in Bangalore showed 28.1%. Table 1 shows the breakdown of ZnPP
levels in 7 cities.
While
elevated ZnPP levels do not translate directly into elevated levels
of lead, tests were done for blood lead levels for those with ZnPP of
35 µg/dL or higher (see Table 2). Of the 4,250 children with elevated
ZnPP, 1,466 or 34% had blood lead levels of 10 µg/dL or higher. The
ratio ranged from 29.2% in Mumbai to 64.4% in Delhi. In the case of
adults, 26.53% had blood lead levels above 10 µg/dL in the 7 cities
combined. Table 3 shows the blood lead levels of those with ZnPP greater
than 35 µg/dL.
Direct
testing for blood lead was carried out randomly for 2,031 children and
adults in 5 cities. Of the 1,852 children tested, 952 or 51.4% had blood
lead levels above 10 µg/dL. 234 children or 12.6% had blood lead of
over 20µg/dL. The percentage of children having 10µg/dL or higher ranged
from 39.9% in Bangalore to 61.9% in Mumbai. In the case of adults, 40.2%
showed blood lead levels above 10µg/dL. Tables 4 and 5 show blood lead
levels regardless of ZnPP levels in 5 cities. Analysis of data reveals
that measurement of blood lead regardless of ZnPP is necessary for detecting
lead levels below 40 µg/dL.
While
we did not study truly random samples of the population, we attempted
to select testing sites that might reflect the range of lead exposure
present in Indian cities. Based on the above, it can be concluded that
over 40% of the children in medium size cities (such as Bangalore) and
over 50% of the children in larger cities in India presently have over
10 µg/dL of blood lead.
At
the time of writing this report, information obtained from the questionnaire
has not been sufficiently analyzed to make a conclusive determination
of the sources and pathways of lead poisoning.
Participating
Institutions
• Bangalore
Baptist Hospital.
• Cantonment
X ray and Laboratory, Bangalore.
• Kempegowda
Institute of Medical Sciences, Bangalore.
• Lake
side Medical Center and Hospital, Bangalore.
• Mallya
Hospital, Bangalore.
• M.S.
Ramaiah Medical College & Hospital, Bangalore.
• St.
John’s National Academy of Health Sciences, Bangalore.
• Gurunanak
Hospital, Mumbai.
• K.J.
Somaiah Medical College & Hospital, Mumbai.
• Bandra
Holy Family Hospital Society, Mumbai.
• B.C.
Roy Memorial Hospital for Children, Calcutta.
• Calcutta
Medical College, Calcutta.
• K.J.
Hospital, Chennai.
• Christian
Medical College, Vellore.
• Indira
Gandhi E.S.I. Hospital, New Delhi.
• National
Institute of Nutrition, Hyderabad.
Acknowledgement
The George Foundation
expresses its appreciation for Admiral O.S. Dawson, who coordinated
the work of the above clinics, and Dr. T. Venkatesh of St. John’s Medical
College for directing the screening tests.
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