Table 3.

Correlation matrix between log-transformed fluoride concentrations in maternal urine, maternal urine adjusted for specific gravity, maternal serum, and amniotic fluid with fluoride concentrations in community water.

Fluoride concentrations	Community water	Maternal urine	Maternal urine adjusted for specific gravity	Maternal serum	Amniotic fluid
Community water	1.00	0.22	0.21	0.39**	0.41**
Maternal urine	0.22	1.00	0.80***	0.38**	0.28
Maternal urine adjusted for specific gravity	0.21	0.80***	1.00	0.41**	0.37*
Maternal serum	0.39**	0.38**	0.30	1.00	0.52***
Amniotic fluid	0.41**	0.28	0.37*	0.52***	1.00

Note: The maternal urine adjusted for specific gravity correlations are based on 47 individuals. One person had a urinary specific gravity of 1, which corresponds to a specific-gravity adjusted fluoride concentration of 0. This is undefined when log-transformed and therefore cannot be included in the computation of correlations. We log-transformed the fluoride concentrations in maternal urine, maternal urine adjusted for specific gravity, maternal serum, and amniotic fluid to make the distributions approximately normal. The community water distribution was not transformed as it was not skewed. *p=0.05 **p=0.01 ***p=0.001