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may be revised in future guidance .' Also, when assessing multiple sources of lead, dust lead concentration may be a more appropriate measurement . The utility o€--ccAlee„tration measurements for identifying section 403 hazards from dust will be further considered in the development of the section 403 rulemaking. Other potential sources of lead that may be present in house dust in addition to lead-based paint and lead-contaminated soil include neighborhood sources, such as demolition of a nearby building, sandblasting of a bridge, or other activities involving structures that may contain lead-based paint . Also, lead may be brought into the home on clothing of residents employed in lead- related occupations, or as the result of some hobbies . Additionally, deteriorated paint which contains some lead, but at levels lower than 1 . 0 mg/cm2 or 0. 501 by weight , could be a source . Depending upon the extent to which these sources contribute lead to interior dust, regular cleaning of the residence may not provide sufficient reduction in the level of lead exposure from dust, and the sources should be identified and controlled. It is often possible to identify these situations through sampling and analysis of the interior dust . Since lead levels treasured by wipe samples ( "dust lead loading" ) are dependent upon both the amount of collectable dust on a surface and the concentration of lead in that dust, high values for either of these two factors could produce high wipe sample lead results . That is, a large amount of low-lead- concentration dust and a small amount of high-lead-concentration dust could result in sir: Llar wipe sample results . Therefore, while low dust lead loading values may indicate that sources that contribute to household dust have been sufficiently controlled, high values could result from any of the following situations : (1) there are some insufficiently controlled sources that continue to contribute significant amounts of lead to the dust; (2) relatively large amounts of low-lead dust are present ; or (3 ) some combination of these occurs. Dust lead concentration measurements can provide insight as to which of these conditions is resulting in high wipe sample values, as well as assist risk assessors in identifying possible sources . For example, if interior paint has been ruled out as a source, and dust concentrations approach those of exterior soil , 'Principal among the studies expected to provide further information on the relationship between dust lead and children' s blood lead levels is the recent Rochester Lead-in-Dust study. This HUD-funded study was conducted by the University of Rochester from May to December of 1993 and included approximately 200 children whose primary source of lead exposure was from house dust . Peer review of this study began in June of 1994 . 7