Table 1

Standardised mortality ratios (SMRs) and inhabitants observed, concerning years engaged in agriculture, number of pregnancies or deliveries, by water system and gender

	SMR		Agriculture		Pregnancy	Delivery
	Males	Females	Males	Females	Females	Females
SMRs were expressed as the ratio of the observed number of deaths and the expected number of deaths. The survival survey was conducted for 6127 days, from 1 August 1967 to 10 May 1984. The expected number of deaths was calculated by multiplying the cumulative observed person-years per decade of age divided according to the water system and sex by the sex specific mortality rates of the general Japanese population in 1976, which was the midpoint of the present observation period.
The other river	0.98	1.06
No. examined			430	542	690	651
No. examined completely			422	522	659	619
Mean number of observed person-days			5235	5600	5491	5487
No. deaths			125	97	136	129
Mean of age			51.8	48.7
Mean years engaged in agriculture (y)			31.3	27.4
Mean number of pregnancies					4.2
Mean number of deliveries						3.8
Jinzu River + the other	0.76	0.96
No. examined			164	261	244	220
No. examined completely			164	197	237	214
Mean number of observed person-days			5514	5666	5605	5579
No. deaths			35	30	41	37
Mean of age			50.4	50.1
Mean years engaged in agriculture (y)			30.4	29.6
Mean number of pregnancies					4.4
Mean number of deliveries						4.0
Jinzu River	0.90	1.05
No. examined			997	1245	1625	1539
No. examined completely			995	1239	1599	1515
Mean number of observed person-days			5328	5513	5501	5491
No. deaths			280	259	336	323
Mean of age			51.7	49.6
Mean years engaged in agriculture (y)			31.8	28.3
Mean number of pregnancies					4.3
Mean number of deliveries						3.9