Cincinnati study variables

The Cincinnati study also has found an effect of prenatal lead exposure on gestational age, measured in weeks as a continuous variable. One analysis (Dietrich et al, 1986) indicated that gestational age was reduced by approximately 0.6 week for each natural log unit of prenatal maternal blood lead (PbB measurements were transformed to natural logarithms for these analyses to better approximate a normal distribution). Also related to these findings is the cross-sectional study by Moore et al (1982), which has shown a significant relationship between pre-term delivery and either maternal or cord PbB levels in Glasgow, Scotland. This relationship held even after adjustment for a number of possible confounders. 

SEM statistical frameworks for such studies were examined and first applied to these questions by researchers at the University of Cincinnati (Bornschein et al., 1985 Succop et al., 1998). SEM permits allocation of the variance in a set of interconnected outcomes to those directly affecting the dependent variable and those following indirect pathways. Put differently, the modeling approach stratifies the explanatory variables relevant to lead exposures into exogenous and endogenous variables. Endogenous intermediate variables include dust, soil, and paint Pb, and the principal outcome endogenous variable is PbB. 

Children in Cincinnati, OH prospective Pb study (N = 165), aged 3-36 months Variable PbB versus age Ratio of Zn-bound to total EP At 33 months, all EP is in the Zn form, versus a minimum at 3 months Hammond et al. (1985)... 

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