Table 2. Urinary mercury levels (μg/g Cr) among children with and without amalgam fillings.

Group	N	Geometric Mean	Median	Range
Referent	182	1.4	1.2	0.3-16.6
Amalgam (total)	180	1.6	1.4	0.2-26.3
By total number of amalgams at the time of participation (N)
<=2	116	1.7	1.5	0.2-26.3
>2	64	1.4	1.2	0.3-17.5
By total number of visible amalgam surfaces at the time of participation (N)
<=2	90	1.7	1.7	0.2-26.3
>2	90	1.3	1.3	0.3-17.5
By time since first filling (months)
<=30	84	1.3	1.1	0.2-26.3
>30	96	1 8†, ‡	1.7	0.3-16.6
By cumulative exposure dose (visible surface-months)
<=60	91	1.5	1.3	0.2-26.3
>60	89	1.6	1.5	0.3-17.5

Note: Controlling for age, sex, family income, hot-food consumption, gum chewing, and fish consumption.

^†P<0.05, compared to referents;

^‡P<0.05 compared to <= 30 months group