Council on Environmental Health
Article Review

Prepared by: Helen J. Binns, MD, MPH
February 2009

TITLE
US Children’s Exposure to Residential Dust Lead, 1999-2004: II. The Contribution of Lead-contaminated Dust to Children’s Blood Lead Levels

AUTHORS
Dixon SL, Gaitens JM, Jacobs DJ, Strauss W, Nagaraja J, Pivetz T, Wilson JW, Ashley PJ

FIND IT AT
Environmental Health Perspectives, online 14 November 2008
http://www.ncbi.nlm.nih.gov/pubmed/19337524

THE PROBLEM
In 2001, the U.S. EPA established a floor dust lead standard of 40 mg lead/sq.ft. as a level that would protect 95% of US children from having a blood lead level (BLL) ³15 mg/dL.  Lead loadings below this are currently deemed safe for children.  This study is the first to examine the contribution of floor dust lead and other demographic and housing-related variables to children’s blood lead levels in a nationally representative sample. 

WHAT THEY DID
Data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES) were analyzed, including paired blood lead and home floor and window sill dust lead loadings from 2155 children aged 12-60 months.  731 children (34%) lived in a home built before 1978.  Linear regression and logistic regression techniques were used to evaluate demographic (child age, family poverty status, race/ethnicity, country of birth), housing (home-apartment type, floor dust lead, floor condition, window sill dust lead, renovation, paint deterioration) and tobacco exposure (smoking inside home, child cotinine level) influences on children’s blood lead levels. 

WHAT THEY FOUND
The population weighted geometric mean BLL was 2.0 mg/dL; 2% had BLL ³10 mg/dL and 9% had BLL ³5 mg/dL.  Risk factors associated with higher blood lead levels included: demographic characteristics (young age, poverty, Non-Hispanic black, born in Mexico), housing characteristics (living in old home, home renovation in past 12 months, poor paint conditions in home, and home with rough/cracked floor surfaces) and tobacco exposures (someone smokes inside the home, higher child cotinine level).

Data were used to predict for an average child (controlling for the covariates listed above) the percentage with a BLL ³10 mg/dL and ³5 mg/dL based on various floor dust lead loading levels (see table).

 

Floor dust lead

% children with BLL ³10 mg/dL

% children with BLL ³5 mg/dL

40 mg lead/sq.ft

11.5%

51.8%

12 mg lead/sq.ft

4.6%

26.8%

DISCUSSION
The good news is that when you include new homes, the average floor dust lead in US homes is 1.1 mg lead/sq.ft. (see Jacobs et al 2002), so in many homes floor dust lead levels are low.  Further, after older homes are fixed, the floor dust lead levels go down and stay down (from 14 mg lead/sq.ft. at clearance dust wipe sampling [after repairs] to 4.8 mg lead/sq.ft. six years later) (see Wilson et al 2006).  The trick now is to find older homes and get them fixed to prevent childhood lead exposures and keep children’s blood lead levels low.

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