Lead poisoning is one of the most harmful pollutant in children since it permanently effects the growth and intelligence.
To evaluate the lead problem in Bangkok children and identify risk factors and impact associated with high lead levels (> 10 micrograms/dL).
The longitudinal study (N = 84) followed blood lead levels at birth, 6, 12, 18 and 24 months of age. Also multiple cross-sectional studies comprising of children under 15 years of age attending the outpatient clinic, Ramathibodi Hospital (N = 511), kindergartens (N = 60) and secondary school students (N = 377) in Bangkok were conducted. The control for under 2 year-old children (N = 188) were those attending Metapracharak Hospital, Nakornprathom Province. Physical examinations were performed by pediatricians. Blood lead levels were assessed by Atomic Absorption Spectrometry. Questionnaires to identify risk factors were completed by parents of under 2-year-old children. Standford Binet tests were performed by psychologists for assessing the IQ in the longitudinal group at 2 years of age.
The mean blood lead levels were increasing with age from 5.57 +/- 2.31 micrograms/dL at birth, to 4.75 +/- 3.25 micrograms/dL at 2 years of age, 6.74 +/- 2.02 micrograms/dL in kindergartens, and 9.03 +/- 3.65 micrograms/dL in secondary school students. They were in the acceptable range. However, the proportion of blood lead higher than 10 micrograms/dL were increasing from 1 to 6, 10 per cent at birth to 6 per cent at 2 years of age, 10 per cent in kindergartens and 35 per cent in secondary school students. The mean lead level in Bangkok children under 2 years of age was higher than those of the control group in Nakornprathom province, but not statistically significant. In addition, there was no identified significant risk factor except that the high lead group had a higher mean age and larger family size than those in the low lead group. In the kindergartens and secondary school, males had higher lead levels than females in the same age group.
The blood lead levels in Bangkok children were not as high as expected. On the contrary, they tended to decrease following the reduction of ambient lead levels due to unleaded gasoline usage.