TABLE 1. Distributions of Exposure Levels.

Exposure	Age	Unit	N	Geometric mean (IQRa)
Mercury	Prenatal	μg/l cord blood	38	31 (11–64)
Mercury	Age 7	μg/l whole blood	37	10 (5.5–23)
PCB	Prenatal	μg/l cord blood	37	2.0 (1.3–2.9)
PCB	Age 7	μg/g serum lipid	33	1.6 (0.97–2.9)
PFOA	Prenatal	μg/l cord blood	37	0.68 (0.41–0.98)
PFOA	Age 7	μg/l serum	34	4.3 (3.4–5.8)
PFOS	Prenatal	μg/l cord blood	37	3.1 (2.5–3.9)
PFOS	Age 7	μg/l serum	34	27 (22–35)

^aIQR, interquartile range.