The relationship between blood pressure and blood lead in NHANES III. National Health and Nutritional Examination Survey.

There is no general agreement as to whether low-level lead exposure increases blood pressure. The present study examined the correlation between blood pressure and blood lead in the NHANES III database (1988-1994). Analyses were performed for all adults (> or =20 years), and reported separately for white males (n = 4685), white females (n= 5138), black males (n = 1761) and black females (n = 2197). Significant covariates of blood pressure were selected by stepwise regression. The change in blood pressure that would be associated with a doubling of blood lead was calculated from the adjusted regression coefficients. Mean systolic/diastolic blood pressure was 123/76 mm Hg in white males, 119/70 mm Hg in white females, 126/77 mm Hg in black males and 121/72 mm Hg in black females. Median blood lead was 174 nmol/L (3.6 microg/dL), 101 nmol/L (2.1 microg/dL), 203 nmol/L (4.2 microg/dL) and 111 nmol/L (2.3 microg/dL), respectively. For a doubling of blood lead, the changes in systolic blood pressure were 0.3 (95% confidence interval: -0.2 to 0.7, P= 0.29), 0.1 (-0.4 to 0.5, P = 0.80), 0.9 (0.04 to 1.8, P = 0.04) and 1.2 (0.4 to 2.0, P = 0.004) mm Hg, respectively and the changes in diastolic blood pressure were -0.6 (-0.9 to -0.3, P = 0.0003), -0.2 (-0.5 to -0.1, P = 0.13), 0.3 (-0.3 to 1.0, P = 0.28) and 0.5 (0.01 to 1.1, P = 0.047) mm Hg, respectively. In conclusion, there is no consistent relationship between blood pressure and blood lead in the NHANES III dataset.