Blood lead levels in Chinese children are high, but decreasing.

He, K, S Wang and J Zhang. 2009. Blood lead levels of children and its trend in China. Science of the Total Environment doi:10.1016/j.scitotenv.2009.03.018.

 A new study reports significant declines during the past decade in blood lead levels of boys and girls in China.

The study examined and compared blood lead levels (BLL) from two different periods to look for trends over time. They compared values reported in published studies from 2001 to 2007 with results from a previous study where the same research group reported children's lead levels between measured between 1995 and 2003.

Lead is a dangerous metal to children, in part, because it impacts cognitive development. More than 30 countries, including the US, have adopted a blood lead level standard for children of 100 µg/L (micrograms per liter) of blood (sometimes written as 10 µg/dL). This standard is based on the recognition that such concentrations are associated with lower IQ scores.

This previous survey – completed in 2004 – showed that BLLs in Chinese children was alarmingly high. The average BLL for boys was 96.4 µg/L, with 36.2 percent of boys sampled exceeding the 100 µg/L standard. Girls were slightly lower, with average BLLs of 89.4 with 30.6 percent exceeding the 100 µg/L standard.

In the new study, the authors found that by 2007, boys’ BLLs dropped to an average value of 79.3 with 22.5 percent exceeding standards, whereas girls decreased to 76.9 with 19.6 percent exceeding standards. The authors suggest the declining trend is linked to the 2000 ban of leaded gasoline in China.

While these decreases are a positive sign, these blood levels are still alarmingly high. No thresholds have been set for what constitutes a truly “safe” level of lead in children. Studies have shown lead under 10  µg/L can impair intelligence.