Table 3. Mean±SD and median of selenium levels in serum (S-Se; μmol/L) and erythrocytes (E-Se; nmol/g) by areas, seasons and sex.

	Ninohe PHC		Yokote PHC		Saku PHC		Ishikawa PHC		ANOVA p-value
	Mean±SD	Median	Mean±SD	Median	Mean±SD	Median	Mean±SD	Median
Men　(n)	22		24		19		20
Winter
S-Se	1.72±0.38	1.59	1.72±0.22	1.66	1.52±0.20	1.52	1.84±0.41	1.81	0.02
E-Se	3.60±0.73	3.35	4.12±0.85	3.97	3.52±0.53	3.47	4.54±0.69	4.53	<0.001
Summer
S-Se	1.65±0.27	1.58	1.55±0.32	1.48	1.75±0.32	1.67	1.73±0.22	1.73	0.103
E-Se	4.63±0.57	4.63	3.80±0.94	3.81	3.66±0.64	3.53	4.41±1.07	4.35	<0.001
Mean of winter and summer
S-Se	1.69±0.31	1.57	1.64±0.23	1.57	1.63±0.19	1.63	1.79±0.27	1.80	0.22
E-Se	4.11±0.59	4.02	3.96±0.71	3.87	3.59±0.47	3.61	4.47±0.75	4.42	<0.001
Women　(n)	25		26		23		21
Winter
S-Se	1.61±0.16	1.65	1.64±0.28	1.59	1.74±0.24	1.73	1.65±0.16	1.62	0.173
E-Se	3.58±0.60	3.61	3.48±0.32	3.52	3.41±0.46	3.43	4.32±0.46	4.33	<0.001
Summer
S-Se	1.54±0.14	1.51	1.41±0.29	1.36	1.51±0.23	1.48	1.67±0.16	1.62	0.002
E-Se	3.75±0.56	3.65	3.89±0.43	3.81	3.32±0.47	3.29	3.91±0.53	3.99	<0.001
Mean of winter and summer
S-Se	1.57±0.14	1.57	1.52±0.27	1.50	1.63±0.20	1.58	1.66±0.15	1.62	0.109
E-Se	3.67±0.55	3.65	3.68±0.33	3.64	3.36±0.45	3.30	4.12±0.41	4.06	<0.001