Lead toxicity remains to be a shared concern for many countries, both developed and developing. Despite differences in the sources of exposure, children continue to present a uniquely vulnerable group, especially during the first three years of life 12. In addition to the inhalation route, children may ingest lead through contaminated dust, soil, and drinking water 3. Moreover, they absorb lead at a higher rate than adults and their nervous system is more susceptible to its detrimental toxic effects 23, thus resulting in neurocognitive delay at blood lead concentrations (B-Pb) as low as 100 μg/L [0.48 μmole/L] 45.

An earlier study on working men at low occupational hazard for lead toxicity in Beirut revealed that B-Pb was strongly associated with smoking and commuting 6. Commuting came at no surprise in a country where close to 90% of the fleet of one million vehicles was operating on leaded gasoline 7, until early 2002 when leaded gasoline was banned.

In addition to ambient air lead and passive smoking, children in Lebanon may be exposed to lead through other sources, such as tap water delivered by lead-soldered pipes, paint, and kohl (traditional eyeliner rich in lead). Despite these red flags, childhood lead poisoning has not made the list of national public health priorities. Pediatricians have rarely reported cases of lead poisoning in Lebanese children. This may be attributed to failure to suspect the toxicity, probably reflecting B-Pb in the sub-clinical range (< 200 μg/L).

The blood lead concentration above which public health action should be taken has been reduced by the US Centers for Disease Control and Prevention (CDC) to 100 μg/L, based on the accumulating evidence of lead toxicity at low concentrations 3. This warrants an active approach to understand the magnitude and determinants of lead poisoning among children in Lebanon. The proposed study aims at measuring the prevalence of lead poisoning, defined as B-Pb ≥ 100 μg/L, among children 1–3 years of age, and at identifying the risk factors for elevated blood lead concentrations in this population. It also examines the need for universal blood lead screening.

This is a cross-sectional study on 1–3 year old children presenting for routine check-up at the private, and outpatient pediatric ambulatory services of the American University of Beirut Medical Center (AUBMC), in Beirut-Lebanon. Children this age were targeted because it is the age of greatest hand-to-mouth and crawling exploratory activity, and a period of fast brain growth where exposure to lead is documented to cause irreversible damage 4. AUBMC pediatric private clinics charge regular visit fees, while the outpatient department charges nominal fees. Although AUBMC is a tertiary medical center, patients from all over Lebanon use its ambulatory services as well for primary health care. The majority of patients though come from the city of Beirut and its suburbs, which host more than 30% of the Lebanese population.

In the outpatient department, children were identified from the roster of next day appointments. Those presenting for regular checkup or vaccination were potential candidates for the study. As for the private clinics, three busy pediatricians provided the names of children eligible for the study.

Of 281 children, 133 (47.3%) were girls. The mean age was 23.1 months (SD: 8.6), with a range of 11 to 44 months. The ratio of outpatient department to private clinics subjects was 2 to 1. Figure 1 shows the distribution of B-Pb. The mean B-Pb was 66.0 μg/L (SD: 26.3), with a range of 10 to 160 μg/L and a median of 60.0 μg/L. There were 39 (14%) children with B-Pb ≥ 100 μg/L (Table 1). Children with B-Pb ≥ 100 μg/L came from less educated and lower income families, as compared to those with B-Pb < 100 μg/L (P < 0.01), and a higher proportion of their fathers and mothers worked in manual jobs (P < 0.01) (Table 1). There was no statistically significant difference in B-Pb by sex, with a mean of 67.6 μg/L (SD 26.6) among males and 64.3 μg/L (SD 25.9) among females (P = 0.29).

Almost all the residents of Beirut and its suburbs live in apartment buildings. Table 2, which compares the overall indoor and outdoor environmental conditions of children's residences, revealed that a significantly higher proportion of children with B-Pb ≥ 100 μg/L lived in buildings that were located near traffic-jammed roads (P < 0.03), as compared to those with B-Pb < 100 μg/L. A seasonal effect was also observed with most of the children with B-Pb ≥ 100 μg/L identified in the summer and fall seasons (P < 0.02).

Table 3 compares the distribution of potential risk factors for lead exposure between the two groups of children: those with B-Pb ≥ 100 μg/L and those with B-Pb < 100 μg/L. A B-Pb ≥ 100 μg/L was significantly associated with the use of hot tap water for cooking or preparation of milk (P < 0.03). The application of Kohl to the eyes of children was significantly associated with elevated B-Pb (P < 0.001). Kohl was applied either to the eyes (92.7%), umbilical cord (2.4%), or both (4.9%), mostly in the first 3 months of age (92.5%). In addition, paternal occupations with a potential for moderate to high exposure to lead had a statistically significant association with elevated B-Pb in children (P < 0.01).

A comparison of health status, nutrition, and the status of iron deficiency between the two groups of children revealed that a higher proportion of children with lower B-Pb were reported to have lack of appetite (40% v 21%; P < 0.02) and fatigue (9% v 0%; P < 0.05), as compared to children with high B-Pb (selected variables shown in table 3).

Table 4 presents the findings of the multivariate logistic regression analysis. Elevated B-Pb (≥ 100 μg/L) was associated with paternal manual jobs (odds ratio [OR]: 4.74), residence being located in high traffic areas (OR: 4.59), summer season (OR: 4.39), using hot tap water for cooking (OR: 3.96), exposure to kohl (OR: 2.40), and living in older buildings (OR: 2.01).

We reviewed the characteristics of the children with the highest B-Pb, two children with a B-Pb of 150 μg/L (a 15-month-old girl and a 37-month-old boy) and a 29-month-old boy with a B-Pb of 160 μg/L. The only risk factors consistently identified for the three children were living in older buildings (> 20 years of age), and having moderately to very dusty homes

A prevalence of 14% of blood lead concentrations ≥ 100 μg/L, among 1–3 year old well children presenting for routine pediatric visits in Beirut, is much higher than the prevalence of B-Pb ≥ 100 μg/L reported among children in economically advantaged countries 91011. In these countries, decrease in blood lead concentrations was mainly attributed to the elimination of leaded petrol and lead-soldered food cans. In spite of this, the prevalence of lead poisoning is still high among urban low-income populations, due to other sources of exposure 910. This is also true, although not consistent, in the less advantaged countries, where children are still exposed to lead from leaded gasoline, traditional cosmetics, lead water pipes, and lead-soldered food cans. The reported B-Pb in these countries ranged from a concentration as low as a mean of 19.6 μg/L in Jordan 12, to as high as 50–87% of children having B-Pb ≥ 100 μg/L in Cape Peninsula, South Africa 13, and Dhaka, Bangladesh 14.

The main question to be addressed here is whether there is a need for universal lead screening of children in Lebanon. The cost of universal screening, and of children's anxiety, which are cited by opponents 26, is overweighed by the short and long-term savings of medical care, special education, and losses in productivity reported by proponents 272829. Caution should be exerted in using a cross-sectional clinic-based study to make a recommendation. However, the detection of no children in this study with a B-Pb above 160 μg/L and only 1% with a B-Pb of 150–160 μg/L, and the lack of reported cases of severe childhood poisoning favor targeted screening, addressed at high risk children. The limited resources within the country and the recent decision to ban leaded gasoline further support this recommendation. Pediatricians could provide general hygienic recommendations and screen high-risk children for lead. Children, whose fathers work in occupations with potential exposure to lead, and whose families use kohl, glazed pottery for food preparation, or hot tap water for milk preparation, may be at a higher risk for lead exposure. The use of low cost kits to test for lead in the home environment could supplement the pediatrician's effort to manage elevated B-Pb, especially in the absence of a national lead prevention program. Future research should document the expected drop in B-Pb among children at a national level and examine the contribution of sources, such as tap water, paint and kohl, to elevated B-Pb.

None.

IN designed the study, supervised data collection, performed the statistical analysis, and drafted the manuscript. MN participated in data collection, statistical analysis, and drafting of manuscript. SM participated in study design, data collection and analysis. SK participated in design of questionnaire, data collection and analysis. GS participated in the conception of the study and study design. MM participated in the study conception and design. MA participated in study design, data analysis, and drafting of manuscript. All authors read and approved the final manuscript.

B-Pb, blood lead concentration; AUBMC, American University of Beirut Medical Center; OR, odds ratio; CI, confidence interval.