Dust, lead wipe sampling

Outdoor lead dust was found to be a more potent contaminant of children s hands than indoor lead dust at day care centers in New Orleans boys, in general, had higher hand lead levels than girls. The conclusions were based on lead analysis of hand wipe samples taken before and after children played outdoors at four different day care centers (a private inner-city site, a private outer-city site, a public inner-city site, and a public outer-city site). The private inner-city site had a severely contaminated outdoor play area with measured soil lead concentrations ranging from 287 to 1,878 mg/kg. The outdoor play area at the public inner-city site, where children exhibited the lowest hand lead measurements of any site in the study, had been completely paved over with concrete or rubberized asphalt and had well-maintained equipment (Viverette et al. 1996). 

ASTM. 1998b. ASTM E 1644. Standard practice for hot plate digestion of dust wipe samples for the determination of lead by atomic spectrometry. American Society for Testing and Materials. 

ASTM. 1998f. ASTME 1728. Standard practice for field collection of settled dust samples using wipe sampling methods for lead determination by atomic spectrometry techniques. American Society for Testing and Materials. 

A homeowner or tenant can also do dust wipe sampling to assess the safety of his or her home. This gives a good indication of how much lead dust is collecting around the home from friction and abrasion or deteriorating paint. 

As set forth in U.S. HUD (1995), dust sampling by use of surface wipes is preferred on the basis of ease of use, relative cost, and a generally favorable performance record for routine samplings. For example, children s blood lead levels and dust wipe lead content in the same units are well correlated (Farfel et al., 1994 Lanphear et al., 1995). Certain vacuum collection approaches can also be used with trained operators in research studies. Measuring dust lead loading from hard surfaces is more reliable than firom complex surfaces such as upholstery or carpeting (Ewers et al., 1994). 

A dust-lead hazard is surface dust that contains a mass-per-area concentration of lead equal to or exceeding 40 micrograms per square foot (pg/fC) on floors or 250pg/ft on interior windowsills based on wipe samples. A soil-lead hazard is bare soil that contains total lead equal to or exceeding 400 parts per million (ppm) in a play area or average of 1200 ppm of bare soil in the rest of the yard based on soil samples. 

EPA believes the results from the wipe sampling method are less useful because as discussed in Unit lll.E.S.iv. of this preamble, the agency believes that wipe sampling on carpets is not a reliable indicator of the lead-based paint dust in the carpet. The authors report that in their study non-HEPA vacuums were more effective than HEPA vacuums on upholstery but note The reduced efficiency of the HEPA vacuum cleaner in cleaning... 

Windowsills were also tested. For the dry cloth protocol, 96.4% of the sills that achieved white glove were also confirmed by dust wipe sampling to be below the dust-lead hazard standard for windowsills, and the one sill that did not achieve white glove was also below the standard. For the wet cloth protocol, all of the sills that achieved white glove were also below the dust-lead hazard standard, as were the four sills that did not reach white glove. ... 

Whether your sample is collected with a wipe or a vacuum, it should be sent to a laboratory certified by either the NLLAP or ELPAT. To be sure the laboratory is certified to analyze for lead in dust, call the National Safety CounciTs National Lead Information Clearinghouse (NLIC) hotline at 800-424-LEAD or one of the agencies that run the accreditation programs, listed in Appendix B, under Testing/Laboratory Analysis. 

Three types of surfaces should be tested for lead dust. Samples of dust are taken using a wet wipe (similar to one used for babies) according to a very specific procedure, and these are analyzed in an EPA-approved laboratory according to specified methods. Dust samples from floors should not have more than 100 p.g of lead per square foot. Samples from interior windowsills should not have more than 500 jig per square foot, and those from window troughs and exterior concrete or other rough surfaces, not more than 800 p,g per square foot. 

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