A field comparison of two methods for sampling lead in household dust

Comparability of dust lead measurements has been a difficult problem due to different sampling and analysis techniques. This paper compares two dust s ampling techniques, the U.S. Department of Housing and Urban Development (H UD) dust wipe method and the Lioy, Wainman, Weisel (LWW) sampler. The HUD m ethod specifies using a moist towelette to pick up as much dust as possible in a specified area and estimates total lead lending. The LWW sampler coll ects the dust on preweighed wetted filter media, and provides greater stand ardization of the sampling path and pressure applied. LWW samples were anal yzed using inductively coupled plasma mass spectronomy (no samples below mi nimum detection limit), while HUD samples were analyzed using flame atomic absorption (32% of samples below minimum detection limit). A bootstrapping technique was used in the analysis to contend with those HUD samples below the minimum detection limit. Mixed model equations were generated to predic t HUD values from LWW results, and to examine the effects of sampling locat ion, time, and method. The results indicate that the two samplers performed similarly under field conditions, although the LWW sampler produced consis tently lower lead loading estimates. LWW values that predicted HUD lead cle arance values of 100 mu g/ft(2) for floors and 500 mu g/ft(2) for window si lls were 72 mu g/ft(2) and 275 mu g/ft(2), respectively. To examine interna l reproducibility, duplicate samples were taken using both the HUD and LWW methods. Correlation results within paired samples indicated a statisticall y significantly higher (p < 0.001) internal reproducibility for leed loadin g, for the LWW sampler (r = 0.87), than for the HUD method (r = 0.71). Some of the differences appeared to be related to the analytical methods.