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Table 4. Effect in Adults of Various Ambient Air Concentrations
Assumes inhalation of 23 m3/day and 30% lung retention. 2Assumes 10% absorption from gastrointestinal tract. 3Computed from regression formula: Blood lead = -69.2052 + 54.7605 x log ug Pb absorped daily as given in Chapter 3 of Airborne Lead in Perspective by the National Research Council, llational Academy of Sciences.. 4Excess body burden associated with ambient air exposure above 2.0 ug Pb/m3.
Clearly, according to Table III, the only lead paint concentration
that offers reasonably complete protection is 0.01%.
Even at 0,05%
int, ingestion of only one twentieth of a teaspoon of paint
per day (containing 12.5 ug lead) will nearly double baseline absorption
from food and water (13 ug) in a 1-3 year old child (10 - 18 kg).
Although data on children are limited, the best available evidence in
adults indicates that doubling daily intake (absorption) of lead from
a baseline of 40 ug per day in a 70 kg adult raises blood lead
concentration from about
20 to 35 ug/ 100 &, a level closely associated
with significant impairment of hemoglobin synthesis (10) [See Table 4).
Quadrupling baseline absorption in adults raises blood leads
to greater than 50 ug/ 100 g, a level close to that occasionally associated
with clinical lead poisoning in some children (11).
Ingestion of only
1/10 of a teaspoon of 0.1% lead paint per day more than quadruples
baseline absorption of 13 ug per day in a 1-3 year old child. Thus,
paint containing even 0.1% lead used in residential areas poses a significant potential danger to future generations of children,
Although the data in Table III have not been substantiated by
direct experimental evidence, they certainly are, a. most conservative
estimate of lead ingestion from paint.
Most chips of peeling lead
paint are significantly denser than water.
Table ill is based upon
ingestion of lead chips that are only as dense as water.
pertinent other factors such as dietary deficiency states (low iron
and low calcium) which potentially might predispose to increased
lead absorption from the gut in excess of 10% have not been considered
in this analysis.
Furthermore, no additional safety factor has been
included in these calculations.
Although There may be room for debate regarding whether 0.05%
or 0.01% lead in paint should be the upper acceptable limit, clearly
a level higher than this is unacceptable.
In a recent press release
(12), based upon an independent method of analysis, the American
Academy of Pediatrics strongly recommended that lead paint in excess
of 0.05% lead should not be permitted. Their estimate is in close
agreement with ours.
0.05% is a potential hazard to children prone to pica.
concentration of 0.01% would reasonably protect all children except
those with extreme tendencies for paint ingestion. Independent
analyses support our view that at no time should future use of
paint containing lead in excess of 0.05%, and preferrably not in
excess of 0.01%, be permitted in residential areas.