Lead is commonly found in home and industrial surroundings and causes a variety of adverse health effects(1). Children absorb more lead than adults because of their physiological and metabolic characteristics. In certain areas Africa and Latin America, the prevalence of lead poisoning in children range from 82% to 100%. The prevalence of childhood lead poisoning in China was also very high(2,3). This study aimed to measure the blood lead (PbB) levels among children from 0 to 15 years of age in Hangzhou city, China.

Stratified-cluster-random-sampling survey for the population was performed from March 2000 to March 2002. A total of 636 children (414 males and 222 females) participated in the survey, corresponding to approximately 0.5% of the total number of children aged 0-15 years in Hangzhou. The geometric mean of PbB levels was 75.94 µg/L (ranged from 11.0 µg/L to 380.0 µg/L) with a positive skewness distribution. The overall prevalence rate of lead poisoning was 31.3% (199/636) with the PbB levels of 200 µg/L or higher in 3.9%(25/636), indicating that lead exposure is a very serious problem in these children.

Studies have revealed a direct link between consumption of leaded gasoline and lead levels in childhood(4). The prevalence rate of lead poisoning in our study was 24.7% in children aged 0-6 years, which is significantly lower than the previously survey (39.16%) in Hangzhou in 1997(5). This may be due to, at least partly, the using of lead free gasoline from 1998 in Hangzhou.

The difference of PbB levels (as geometric mean) between female (71.52 µg/L) and male (78.26 µg/L) was not significant (P = 0.064). The prevalence rate was 28.8% (64/636) in female and 32.6% (135/636) in male and the difference was not significant too (P = 0.327). These implied that the female and male could absorb the same lead when they are in the same environments.

1

0-1 month

52

50.91

vs 2-6

6(9.6)

2

1 mo - 1 year

152

60.95

vs 1, 3-6

31(20.4)

3

1-3 year

133

81.45

vs 1,2

48(36.1)

4

3-6 years

129

90.92

vs 1,2

56(43.4)

5

6-11 year

113

90.92

vs 1,2

44(38.9)

6

11-15 year

57

78.84

vs 1,2

15(26.3)

F = 17.910, P = 0.000; x2 = 33.727, P <0.001.
* LSD multiple comparison of geometric mean among subgroups.

In the United States and Australia, the PbB levels are highest in 1- to 2-year-old children and decline at later ages. In this study, we found the PbB levels were increased with age in children younger than 3 years with the highest level in children aged 3-11 years, and then declined at later ages. The differences of PbB levels among different ages were significant (P <0.001) (Table I). The pre valence rates also increased with ages in children younger than 3 years and then decrease in children older than 6 years, with statistically significant difference (P = 0.000). One possible explanation for this discrepancy in age trends is that factors that make younger children more susceptible to lead exposure (i.e., hand-to-mouth behavior, lead absorption physiology) may be superseded by other risk behaviors such as increased outdoor activities or exposure of other sources of lead (i.e., lead in food, toys, pencils and so on).

Zou Chaochun,
Zhao Zhengyan,
The Children’s Hospital,
Zhejiang University School of Medicine,
57# Zhugan Xiang, Hangzhou, 310 003,
China.
E-mail: [email protected]

1. Zou C, Zhao Z, Tang L, Chen Z, Du L. Effects of lead on brainstem auditory evoked potentials in children. J Chin Med, 2003; 116: 565-568.

2. Yan CH, Shen XM, Zhang YW, He JM, Zhou JD, Ao LM, et al. An epidemiological survey on blood lead level and high-risk factors for lead poisoning of children in Shanghai. China J Pediatr, 1998: 36:142-145.

3. Qin R, He SX, Chen RH, Chen XH, Zhao RZ, Dai JG, et al. A survey on blood lead levels of children aged 2-6 years in Jiangsu province. China J Pediatr, 1998; 36:178-179.

4. Thomas VM, Socolow RH, Fanelli JJ, Spiro TG. Effects of reducing lead in gasoline: an analysis of the international experience. Environ Sci Technol, 1999; 33: 3942-3948.

5. Yang RL, Zhao ZY, Chen HY, Li LF, Chen HY, Zhang LZ, et al. Analysis of lead levels in 1320 preschool children of Zhejiang province, Zhejiang University Med Sci, 1999; 28:160-162.