Impact of home carpets on childhood lead intervention study

Blood lead data for a childhood lead exposure study have been reanalyzed to examine the impact of carpets on the effectiveness of a cleaning intervention in 39 New Jersey urban houses. All eligible houses in the study were classified as carpeted and uncarpeted depending on the number of rooms that were carpeted. The cleaning protocol was associated with a significant reduction in the blood lead concentrations for the uncarpeted homes (P = 0.004), whereas no significant change was found for the carpeted homes (P = 0.566). We also completed correlation analyses between the number of cleaning visits and the percentage reduction in blood lead for the carpeted/uncarpeted houses. There was a significant correlation (r = 0.67) between the number of cleanings and blood lead reduction for the uncarpeted homes, but no correlation (r = 0.04) for the carpeted homes. In a multiple regression model that took confounding variables into account, the carpet status (carpeted or uncarpeted) remained a factor of the effect of cleaning on blood lead (P = 0.05). We conclude that the presence of contaminated carpets inhibits the effectiveness of home cleaning despite a high-efficiency particulate air filtered vacuum protocol that removes a substantial amount of lead dust.