Fall in blood lead level in the US population 1999-2012

Abstract

OBJECTIVE: Chronic low-level exposure to lead is thought to be associated with increased blood pressure in adults. Therefore, we analyzed the latest trends in blood lead level in the US population. METHOD: We used the 1999-2012 data on blood lead in the US National Health Nutrition and Examination Survey (NHANES). Participants with blood lead measurements were included. They were stratified according to sampling year, age and gender. Data were analyzed using the complex sampling functions of SPSS version 22. RESULTS: There were 7970, 8946, 8373, 8407, 8266, 8793 and 7920 participants in NHANES 1999-2000, 2001-2002, 2003-2004, 2005-2006, 2007-2008, 2009-2010 and 2011-2012, respectively. Blood lead levels were (geometric mean [95% confidence interval]) 1.77 [1.72-1.81], 1.57 [1.54-1.61], 1.52 [1.48-1.55], 1.41 [1.38-1.44], 1.38 [1.35-1.41], 1.23 [1.21-1.25] and 1.09 [1.06-1.21] for adults aged 20 or above, and 1.43 [1.39-1.47], 1.16 [1.13-1.19], 1.18 [1.15-1.21], 0.99 [0.96-1.01], 0.98 [0.96-1.01], 0.81[0.80-0.83], 0.66 [0.64-0.68] for children, respectively. Both decreasing trends were significant (p<0.001). Compared to children aged 7 or above, children aged 6 or below had significant higher blood lead levels (1999-2000: 1.24 [1.20-1.28] vs. 2.08 [2.01-2.26]; 2001-2002: 1.03 [1.00-1.06] vs. 1.65 [1.57-1.73]; 2003-2004: 1.03 [1.01-1.06] vs. 1.69 [1.61-1.78]; 2005-2006: 0.86 [0.84-0.88] vs. 1.41 [1.35-1.48]; 2007-2008: 0.85 [0.83-0.88]vs. 1.46 [1.40-1.54]; 2009-2010: 0.72 [0.70-0.74] vs. 1.15 [1.10-1.19]; 2011-2012: 0.59 [0.57-0.61] vs. 0.93 [0.88-0.99]; p<0.001). CONCLUSIONS: Blood lead level has been decreasing in the US population during the period 1999-2012. The blood lead level in children aged 6 or below is of concern.