HEALTH
SERVICES IN CHILDHOOD
LEAD
POISONING PREVENTION: THE EXPERIENCE OF THE CAIRO LEAD SURVEY, 1997-1998
Dr.
Carol Pertowski
Introduction
The Egyptian Ministry
of Health and Population has been interested in childhood lead toxicity
for many years. Over the past three years, the Ministry of Health and
Population has been working with the U.S. Centers for Disease Control
and Prevention (CDC) on childhood lead toxicity -- on an investigation
of an acute outbreak of lead poisoning in a rural area and a survey
of blood lead levels among children in Cairo. This presentation describes
the experience during planning and implementation of the Cairo lead
survey, and highlights what we learned about the role of public health
and health services in childhood lead poisoning prevention. As the study
is still ongoing, the presentation will not include the results of the
study.
Background
The survey is being
conducted by the Field Epidemiology Training Program (FETP) of the Ministry
of Health and Population. The FETP is a collaboration between the U.S.
CDC and the Ministry of Health and Population (MOH&P) to provide
a two year training program for physicians in practical epidemiology.
The Egyptian FETP was established in 1993. Trainees, and graduates of
the program who work as staff epidemiologists, track public health problems,
including infectious diseases such as meningitis and hepatitis, but
are also interested in environmental health issues.
The FETP was interested
in assessing the extent of lead toxicity among young children living
in Cairo. In 1996, the CDC and the FETP began a collaboration on a study
of blood lead levels among children in Cairo. While planning the Cairo
lead survey, the FETP was notified of an outbreak of gastrointestinal
disease in southern Egypt that was subsequently shown to have been caused
by lead toxicity. In another session at this conference, there has been
a presentation describing how the source of that outbreak was one that
had not been of concern previously in Egypt, -- flour contaminated with
lead during the grinding process.
In 1997, the CDC
and FETP began a population-based study of blood lead and anemia levels
among children ages 2-6 years living in selected districts or regions
of Cairo. Cairo is divided into 22 districts or zones. The investigators
have completed the survey in two districts, and so far have enrolled
more than 350 children in the study. The team plans to continue the
survey in another district later this year. The survey is a stratified
sample of young children living in the district, and involves a questionnaire
for the parents, a blood sample from the child which was tested for
lead and anemia, and collection of dust, soil, water, paint, and flour
samples for lead analysis. Analysis of the data is still in progress.
During the planning
of the survey, the FETP pulled together an informal advisory group of
public health physicians at the national and district level. The group
considered the survey design and the services that would be needed by
children with elevated blood lead levels and anemia. The next step was
working through the approval process within the MOH&P and other
Ministries. After all of the approvals had been obtained, an announcement
of the survey in the newspaper informed the people living in the districts
in which the survey would be carried out that this was an event approved
by the MOH&P. Also, approvals from the local and district preventive
health directors were obtained. Members of these agencies were important
members of the teams that performed the survey, as they were familiar
with the neighborhoods and could help assure that there would be participation
in the survey.
In designing and
implementing the study, we addressed several issues that would need
to be considered in the development of a lead poisoning prevention program.
Selection of
the Population at Risk
Young children are
at greatest risk for health effects from exposure to lead. There were
a few studies on lead toxicity in Egypt, but none of these studies focused
on young children, and none were population-based. In selecting the
population for the survey, we targeted children ages 2 - 6 years. We
excluded very young children as we expected difficulties with parents’
granting permission for blood samples from children younger than age
2 years.
Staffing
The survey team
was composed of an FETP epidemiologist, a phlebotomist, a laboratorian
to collect environmental samples, and a representative from one of the
local health clinics. The epidemiologist explained and conducted the
survey, and returned to the home to explain the results of the blood
lead and anemia tests. As noted earlier, the staff from local clinics
were helpful in navigating the neighborhoods and assuring participation
in the survey.
Survey Questions
- Addressing Risk Factors
The survey questions
addressed risk factors for lead exposure among the children. We first
reviewed the literature to see what were the likely sources of lead
exposure for children in Cairo (Table 1).
Table 1. Possible
sources of lead exposure for children in Cairo.
Soil or dust
contaminated with leaded gasoline
Pottery
Soldered cans
Cosmetics
Water
Take-home from
occupational exposures
Flour
Although lead was
phased out of gasoline in Cairo around the time we began the study,
we thought that previous use of leaded gasoline may have contaminated
dust or soil. As a result of the investigation of the outbreak in rural
areas, we were also concerned that flour ground in small mills may have
been contaminated with lead. In some areas, cottage industries such
as battery recycling could be a source of exposure. We were not particularly
concerned about lead-based paint as a source of exposure.
Supplies for
Sample Collection
Equipment used for
blood collection, e.g., syringes, tubes, alcohol wipes, have to be tested
to assure that it is lead free. This is very important as the amount
of lead in blood that is considered to be dangerous is so small. In
our survey, CDC initially analyzed the blood collection materials for
presence of lead. CDC staff have trained MOHP laboratorians in this
process, so the survey will not be too dependent on the CDC in the future.
Collaboration
with the Laboratory
The laboratory has
been an important partner in all phases of the project. Staff from the
Central Public Health Laboratory of the MOH&P analyze all of the
blood samples for lead and also perform hemoglobin analysis and complete
blood counts. The lab also supplies the results to the phlebotomist
and to the survey team.
CDC staff have worked
closely with the Egyptians to assure that the blood lead analysis uses
appropriate quality assurance and control measures. There have been
problems with events like power failures interfering with blood lead
analyses, but the lab currently has a 97% agreement with blinded samples
sent from CDC for quality control purposes.
Follow-up with
Families of Children with Abnormal Test Results
After the blood
lead and anemia results were obtained, a FETP staff member visited each
family whose child had an elevated blood lead level or anemia and discussed
the results. For children with anemia, the staff member gave the parents
the name of a physician or local health clinic that could provide follow-up.
For children with blood lead levels over 20 µg/dL, the staff member
requested a follow up sample to confirm the elevated level. For families
with children with blood lead levels over 10 µg/dL, staff explained
how hand washing can reduce exposure to lead, and discussed the possible
sources of lead in the home.
Another issue in
follow up is whether to recommend testing of family members of children
with blood lead levels confirmed to be over 20 µg/dL. Other children
in the family may have similar sources of lead exposure and may need
to be screened for lead toxicity. We also need to evaluate the results
of the survey and sampling to determine what the likely sources of exposure
are, and what steps families can take to reduce exposure.
Referral for
Children with Elevated Blood Lead Levels
Anemia
For children with
severe anemia, i.e. < 9 gm/dL, we arranged for referral to a university
professor. Our plan was to refer children with mild to moderate anemia
(levels from 9 - 11 gm/dL), to the local health clinic. In the second
district, preliminary data suggest that a high percentage of children
have levels in the mild to moderate range. We suspect that iron deficiency
anemia and intestinal parasites may be the major cause of the anemia.
We were concerned that the local clinic would not have the resources
either to confirm the diagnosis or to treat the children. The Central
Public Health Laboratory have agreed to analyze stool samples for ova
and parasites and to send lab staff to the local clinic on certain days
to collect these specimens. FETP staff are currently working with other
agencies to obtain multivitamins and appropriate medicines for the local
clinic. They will then be working with local clinic staff to assure
that these medicines are available to children in the study.
Elevated blood
lead levels
For children with
levels confirmed as > 20 µg/dL, we arranged for referral to a university
professor with an interest in lead toxicity. The professor will continue
to follow the child, and give chelation therapy if levels are very high.
For children with
levels from 10 -20 µg/dL, the epidemiologist who gave the parents the
results of the study stressed the likely sources of exposure, and basic
control measures, such as hand washing, that parents could use.
Lessons Learned
Usefulness
of data
The survey has taken
a while to implement and the analyses are not final, but we are already
getting positive feedback from policy makers about the usefulness of
the data. Because the survey is population-based, the data from the
survey participants are representative of the children in the district.
Therefore, the data from each district will be useful in planning and
supporting the development of educational activities and preventive
measures such as supplying vitamins and other medicines for children
living there. As the survey includes more than 22 districts in Cairo,
we will get a more accurate picture of childhood lead toxicity in the
city.
Need to supplement
existing resources and services
Looking for and
finding lead toxicity in a community may be calling attention to a health
problem that previously may not have been a concern to the local health
care providers. In some cases, the providers may need resources or staff
to screen children for lead and implement appropriate control measures.
There may be a need to provide education about lead toxicity at different
levels of the health care system. There will be a need for more health
care providers, more equipment for blood collection, and assurance of
the quality of the blood lead testing (especially for children with
very high levels), referral of children with very high levels to specialists,
providing vitamins, and for implementing basic control measures such
as hand washing with soap.
Educational
information
In Egypt, there
were no existing materials for educating either health care providers
or parents about the risks of lead poisoning. Development of such materials,
focused on the exposures likely in the area, are needed since many districts
are found to have their populations at risk. The importance of basic
prevention measures, such as hand washing, must be stressed in these
educational materials.
Environmental
exposures
Through the design
and implementation of this survey, we have considered the various sources
of lead exposure for children. From the outbreak of lead toxicity traced
to flour contaminated during the grinding process, we recognized that
unusual sources of lead can cause significant exposure to lead. The
survey has also highlighted the important role of public health in identifying
the sources of lead exposure for a community and in developing appropriate
educational materials or other basic interventions such as multivitamins
for local health clinics.
When the survey
results are available, they should provide information on the sources
of lead exposure for children that will need community-level interventions
for changes in policy. The FETP plans to summarize the results of the
survey, and share them with the appropriate agencies.
