Blood lead concentrations in one- to seven-year-old children in Mashhad, Iran

Blood lead concentrations in one- to seven-year-old children in Mashhad, Iran

To the Editor:

In spite of the reported studies on blood lead level (BLL) of children in various countries, to the best our knowledge there has been no report on BLL in children of I. R. Iran. We studied the BLL of children in the emergency pediatric ward and outpatient clinic of Imam Reza Hospital, Mashhad University of Medical Sciences (MUMS) between March 2003 and February 2004. The hospital is a specialty center in Khorassan province and serves a population of around 2.5 million people.

The Investigational Review Board and the Medical Ethics Committee of MUMS approved the study. Informed consents were obtained from the parents of children prior to study. Both symptomatic (convulsive only) and healthy children were studied. Venous blood samples (3 ml) were drawn in standard EDTA tubes. BLL was determined by an atomic absorption (Perkin Elmer Model 3030) using heated graphite atomization technique with a detection limit of 10 μg/L in the Toxicology Laboratory of the hospital within a week.

BLL of 206 children aged 1–7 years were determined. The mean age (± SD) of the children was 40.40 (± 18.66) months. The mean (± SD) BLL was 12.19 (± 3.35) μg/dl with a minimum of 1.3 μg/dl and maximum of 24.7 μg/dl. The majority of children (59.2%) had BLL of 10–15 μg/dl and 16.6% had BLL over 15 μg/dl. In total, 154 children (75.8%) had BLL over 10 μg/dl.

The blood lead concentrations in different age groups of the children are shown in the table. There were no statistically significant differences in BLL among the age groups. It is also noteworthy that there was no significant correlation between the age groups and BLL of the children.

Table 1. Blood lead level (BLL) in different age groups of children in Imam Reza Hospital of Mashhad, Iran

Age (months)	12–23	24–35	36–47	48–59	60–71	72–83
Number of children	42	45	32	35	29	23
Mean BLL (μg/dl)	12.4	12.2	12.1	11.7	11.9	13.5
Standard Deviation	10.5	9.4	11.6	9.6	11.2	19.8

In a much larger study conducted in California involving 5115 children aged one to six years old, only 7.2% had BLL of over 10 μg/ldl (1). In Uruguayan children aged less than 14 years, 36% had BLL over 10 μg/ldl and the mean was 9.6 μg/ldl (2). In city of Wuxi, China, 27.3% of 117 children were reported to have BLL of above 10 μg/dl and the mean was 8.2 μg/dl (3). A study in Vancouver, Canada of 177 children aged between two and three years old, 8.1% had a BLL higher than 10 μg/dl (4).

In another survey on 436 children aged 6 months to 6 years old in Massachusetts, 22% of the subjects had BLL higher than 10 μg/dl (5). In North Carolina, 20.2% out of 20,720 children between 6 months to 6 years old were found to have a BLL of more than 10 μg/dl (6). The mean BLL in 397 children aged 2–6 years of Jakarta, Indonesia was 86 μg/ldl (7). The higher BLL in our sample might be due to more environmental lead pollution. For instance, we found lead in the gasoline samples collected in Mashhad a few months ago, despite the formal announcement a few years ago that the gasoline is unleaded.

Based on the results of this pilot study, there is a need for a more comprehensive study on BLL of children both in Mashhad and throughout the country, and investigations into the sources of lead exposure are also required.