A Suggested Lead Surface Concentration Standard for Final Clearance of Floors in Commercial and Industrial Buildings

Abstract

Standards for final clearance after lead abatement have been established for child-related facilities and public housing in the United States. For these existing standards final clearance for lead is based on surface loading. However, no standards have been suggested for buildings that are identified as not child-related or public housing (e.g. commercial buildings). Calculations have now been made to determine a proposed final clearance loading value for buildings or structures that are not child-related or public housing and for the two situations: lead-free and non-lead-free. The values proposed for floors are 1,100 µg Pb·ft^–2 for lead-free buildings and 1,000 µg Pb·ft^–2 for non-lead-free buildings. Blood lead levels in adults should not increase after exposure at or below these suggested lead-loading values.

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“…The three bulk readings for lead fall within the background range for soil and house dust. The surface wipe concentrations (10.5-17.3 ÌgWft -2 ) also fall within the levels (40 ÌgWft -2 , floors; 250 ÌgWft -2 , sills) listed in the Federal Register guidelines [6] and are thus fully consistent with the bulk readings (also see [7]). Taken together, these findings provide no evidence of a health risk from lead.…”

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“…One author has suggested criteria based upon lead-loading values. Lange [2001] proposed a clearance level of 1000 µg/ft 2 for floors of non-lead free buildings and 1100 µg/ft 2 for lead-free buildings, and states that "no increase in BLL should occur for adults associated or exposed within a commercial structure" at the latter level. These proposed clearance levels are based on calculations that make a number of intentionally conservative assumptions such as: a) Lead uptake following ingestion is 35% absorption of lead in the gastrointestinal system, b) Fingers have a total "touch" area of 10 cm 2 and 100% of the entire presumed lead content on all 10 fingers is taken up, c) The average 'normal' environmental lead dose (from 'uncontaminated food/water/air) is 20 µg per day, d) The weight of the exposed person is 70 kg, and e) Daily lead excretion is limited to an average of 48 µg.…”

“…These proposed clearance levels are based on calculations that make a number of intentionally conservative assumptions such as: a) Lead uptake following ingestion is 35% absorption of lead in the gastrointestinal system, b) Fingers have a total "touch" area of 10 cm 2 and 100% of the entire presumed lead content on all 10 fingers is taken up, c) The average 'normal' environmental lead dose (from 'uncontaminated food/water/air) is 20 µg per day, d) The weight of the exposed person is 70 kg, and e) Daily lead excretion is limited to an average of 48 µg. Lange [2001] notes that "use of the proposed values would provide a standard for non-child-related premises (e.g. commercial, industrial, office)…" but cautions that, " Further investigation is warranted to evaluate exposure and subsequent dose to adults from surface lead.…”