Table 2

Linear regression analyses of water quality indicator levels and type 1 diabetes incidence rate at both community and regional levels

Water quality indicator	Community level		Regional level
	Linear regression		Linear regression
	β	P value	β	P value
Nutrients and metals
Ammonia	0.010	0.901	−0.044	0.758
DOC	−0.094	0.496	−0.162	0.589
Nitrate(ite)	−0.015	0.868	0.319	0.094
Kjeldahl nitrogen	−0.146	0.220	0.061	0.825
Total phosphorus	0.095	0.214	0.047	0.797
Aluminum	0.014	0.868	−0.022	0.875
Antimony	−0.166	0.143	0.089	0.525
Arsenic	0.268	0.013*	−0.173	0.458
Barium	0.020	0.860	−0.478	0.009*
Cadmium	0.005	0.975	1.252	0.138
Chromium	0.040	0.677	0.212	0.524
Copper	−0.157	0.061	−0.139	0.502
Iron	0.159	0.137	0.025	0.904
Lead	0.119	0.243	−0.031	0.853
Magnesium	−0.031	0.719	0.083	0.606
Manganese	0.001	0.989	0.098	0.488
Mercury	0.081	0.590	−0.974	0.251
Nickel	0.043	0.585	−0.354	0.050*
Selenium	0.007	0.963	−0.021	0.961
Uranium	−0.231	0.056	−0.191	0.328
Zinc	−0.029	0.776	−0.130	0.558
Major ions
Boron	0.216	0.109	−0.176	0.480
Bromide	−0.015	0.860	0.038	0.860
Calcium	−0.560	0.116	0.046	0.740
Chloride	1.255	0.082	0.202	0.310
Fluoride	0.202	0.005*	0.177	0.325
Potassium	−0.133	0.287	−0.185	0.232
Sodium	−0.319	0.384	−0.165	0.452
Sulfate	0.964	0.076	0.107	0.490

*Statistically significant P<0.05.
DOC, dissolved organic carbon.