Table 6

Hazard ratios: cumulative lead exposure

Cumulative values (μg/dl years)Relative to external control group (n=236)Relative to internal control group (n=230)
Hazard ratio95% CIHazard ratio95% CI
With adjustment only for country
<120 (n=124)1.31(1.02 to 1.68)0.93(0.74 to 1.17)
120–220 (n=133)1.38(1.09 to 1.75)0.98(0.78 to 1.22)
220–420 (n=136)1.03(0.81 to 1.31)0.73(0.58 to 0.91)
420+ (n=148)1.48(1.17 to 1.86)1.05(0.84 to 1.30)
With adjustment for country, mother’s age, smoking, and primiparity
<120 (n=124)1.28(1.00 to 1.65)0.94(0.73 to 1.18)
120–220 (n=133)1.33(1.05 to 1.70)0.97(0.78 to 1.22)
220–420 (n=136)0.97(0.76 to 1.24)0.71(0.56 to 0.89)
420+ (n=148)1.43(1.13 to 1.81)1.04(0.83 to 1.31)