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Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

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AX6-10<br />

Table AX6-2.2 (cont’d). Meta- and Pooled-Analyses <strong>of</strong> Neurocognitive Ability in Children<br />

Reference, Study<br />

Location, and Period Study Description Pb Measurement Findings, Interpretation<br />

Pocock et al. (1994) Meta-analysis <strong>of</strong> five prospective and fourteen crosssectional<br />

studies (including tooth and blood tissues)<br />

were included. The fixed effect method <strong>of</strong><br />

Thompson and Pocock (1992) was employed.<br />

Only blood Pb at or near two yrs <strong>of</strong> age was<br />

considered <strong>for</strong> the prospective studies.<br />

Blood Pb<br />

Tooth Pb<br />

Overall conclusion was that a doubling <strong>of</strong> blood Pb levels<br />

from 10 to 20 µg/dL, or tooth Pb from 5 to 10 µg/g was<br />

associated with an avg estimated deficit in IQ <strong>of</strong> ~1-2<br />

points. Authors caution interpretation <strong>of</strong> these results and<br />

Pb literature in general, citing questions about<br />

representativeness <strong>of</strong> the samples, residual confounding,<br />

selection bias, and reverse causality.

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