Kindergarten readiness
2 IQ points behind on day 1Letter recognition. Number sense. Working memory. The kindergarten readiness battery is essentially an IQ proxy, and Lanphear’s 1,333-child pooled analysis found 1 IQ point lost per 2.4 µg/dL of mean childhood blood lead. A toddler who averaged 5 µg/dL enters kindergarten about 2 points behind a zero-lead peer. Invisible in the room. Measurable on every test from there forward.