MEASUREMENT ERROR AND ITS IMPACT ON THE ESTIMATED RELATIONSHIP BETWEEN DUST LEAD AND CHILDRENS BLOOD LEAD

Objective. Lead-contaminated house dust is a major contributor to lead intake among urban children, but the reliabilities of various dust le ad measurement methods and their impact on the estimated correlations between dust lead and children's blood lead levels are unknown, Method s. Repeated field measurements of lead-contaminated dust from children 's homes were taken from 16 housing units using five dust lead measure ment methods, Estimates of measurement error were used to obtain relia bility ratios for the dust lead measurements, which were then used to correct estimated correlations between lead-contaminated dust and chil dren's blood lead, Results, Reliability varied over methods and surfac e types (from 0.0 to 0.8), but wipe loading and the BRM vacuum loading methods generally had greater reliability, Technician effects, inadve rtent field exposure to lead, contamination of collection equipment, a nd laboratory instrument error were found to contribute little to tota l measurement error, Corrected correlations between blood lead and wip e loading measurements were 7 to 104% higher than uncorrected correlat ions, The multiple R(2) and partial R(2) for a wipe composite measurem ent in a multivariate regression model increased from 0.43 to 0.64 and from 0.053 to 0.26, respectively, after correction for measurement er ror bias, Conclusions, Variation in lead deposition within small areas and variations in collection inherent to the devices are major contri butors to measurement error, Measurement error causes dramatic underes timation of correlation between lead-contaminated house dust and child ren's blood lead. (C) 1997 Academic Press