Table 2 Characteristics of included studies, by researching regions
From: The trend of lead poisoning rate in Chinese population aged 0–18 years old: a meta-analysis
Eastern zone18–50 | Central zone51–56 | Western zone57–68 | National wide69–72 | |
|---|---|---|---|---|
Number of studies | 33 | 6 | 12 | 4 |
Published year | ||||
1990–2000 | 9 | 1 | 5 | 0 |
2001–2005 | 15 | 4 | 3 | 4 |
2006–2012 | 9 | 1 | 4 | 0 |
Sample size | ||||
<500 | 8 | 2 | 7 | 0 |
500–1499 | 15 | 3 | 3 | 0 |
1500–2999 | 8 | 1 | 1 | 0 |
≥3000 | 2 | 0 | 1 | 4 |