Relationship between different sources of drinking water, water quality improvement and gastric cancer mortality in Changle County - A retrospective-cohort study in high incidence area

Table 2 Types of the drinking water supply and gastric cancer mortality rates for seven towns, Zhanggang (1/10⁵)

Types of drinking		Male	Female	Total
water supply
River water (1)		122.83	46.10	86.03
		(107/87113)	(37/80263)	(144/167376)
Shallow well (2)		85.02	36.06	62.03
		(650/764555)	(244/676618)	(894/1441173)
Tap water (3)		51.31	3.86	29.78
		(16/31181)	(1/25906)	(17/57087)
RR		2.39	11.94	2.89
χ2	(1:3)	10.617	8.618	18.005
P		< 0.01	< 0.01	< 0.01
RR		1.66	9.34	2.08
χ2	(2:3)	3.673	6.524	8.872
P		> 0.01	> 0.05	> 0.01
RR		1.44	1.28	1.39
χ2	(1:2)	12.158	1.686	13.017
P		< 0.01	< 0.05	< 0.01