Residential deleading: effects on the blood lead levels of lead-poisoned children.

Acute elevations of venous blood lead levels (PbB) are periodically reported in children with chronic lead poisoning, during deleading of their houses. To evaluate this phenomenon 114 preschool children who entered the Massachusetts Childhood Lead Poisoning Prevention Program case management system during 1984 and 1985 were retrospectively studied. PbB increased from a mean (+/- SE) of 1.76 +/- 0.03 mumol/L (36.4 +/- 0.6 micrograms/dL) prior to deleading to 2.03 +/- 0.07 mumol/L (42.1 +/- 1.5 micrograms/dL) during deleading (P less than .001). Among 41 subjects for whom deleading was done by dry scraping and sanding, the mean mid-deleading PbB was higher than the pre-deleading PbB by 0.44 +/- 0.12 mumol/L (9.1 +/- 2.4 micrograms/dL). However, when deleading was done by covering or replacement of painted surfaces in the residences of 12 subjects, mid-deleading PbB decreased 0.11 +/- 0.12 mumol/L (2.25 +/- 2.4 micrograms/dL) (P less than .005). In a subset of 59 subjects who had no chelation therapy and were available for follow-up 250 +/- 14 days after completion of deleading, PbB had decreased from 1.72 +/- 0.04 mumol/L (35.7 +/- 0.9 micrograms/dL) to 1.24 +/- 0.04 mumol/L (25.5 +/- 0.9 micrograms/dL) (P less than .001). The long-term effect of deleading is a significant reduction in PbB. However, deleading resulted in a significant, albeit transient, increase in PbB.