The possible association between the risk of gastric cancer and the levels of calcium, magnesium, and nitrate in drinking water from municipal supplies was investigated in a matched case-control study in Taiwan. Records of gastric cancer deaths among eligible residents in Taiwan from 1987 through 1991 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to the cases by sex, year-of-birth, and year-of-death. Each matched control was selected randomly from the set of possible controls for each case. Data on calcium, magnesium, and nitrate levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation. The municipality of residence of the cases and controls was assumed to be the source of the subject's calcium, magnesium, and nitrate exposure via drinking water. The subjects were divided into tertiles according to the levels of calcium, magnesium, and nitrate in their drinking water. The results of the present study show that there is a significant positive association between drinking water nitrate exposure and gastric cancer mortality. The present study also suggests that there was a significant protective effect of calcium intake from drinking water on the risk of gastric cancer. Magnesium also exerts a protective effect against gastric cancer, but only for the group with the highest levels.

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The possible association between the risk of colon cancer and the levels of calcium and magnesium in drinking water from municipal supplies was investigated in a matched case‐control study in Taiwan. All eligible colon cancer deaths (1714 cases) of Taiwan residents from 1989 through 1993 were compared with deaths from other causes (1714 controls), and the levels of calcium and magnesium in drinking water of these residents were determined. Data on calcium and magnesium levels in drinking water throughout Taiwan were obtained from the Taiwan Water Supply Corporation. The control group consisted of people who died from other causes and the controls were pair‐matched to the cases by sex, year‐of‐birth, and year‐of‐death. The adjusted odd ratios (95% confidence interval) were 0.79 (0.64–0.98) for the group with water calcium levels between 24.4 and 42.3 mg/liter and 0.58 (0.47–0.73) for the group with calcium levels of 42.4 mg/liter or more. The adjusted odd ratios were not statistically significant for the relationship between magnesium levels in drinking water and colon cancer. The results of the present study show that there is a significant protective effect of calcium intake from drinking water against colon cancer

In spring, windblown dust storms originating in the deserts of Mongolia and China travel to Taipei city. These occurrences are known as Asian dust storm (ADS) events. The objective of this study was to assess the possible associations of constituents of ADS with hospital pneumonia admissions of residents in Taipei, Taiwan, during the period 1996-2001. Fifty-four dust storm episodes were identified and were classified as index days. Daily pneumonia admissions on the index days were compared with admissions on comparison days. Two comparison days for each index day, 7 d before the index days and 7 d after the index days, were selected. The study results indicated a statistically significant association between ADS events and daily pneumonia admissions 1 d after the event. It is worthwhile to pay more attention to ADS events and health in the future based on the findings in this investigation.

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To investigate the relationship between petrochemical air pollution and female lung cancer, we conducted a matched case-control study among women who had died in Taiwan from 1990 through 1994. Data about all eligible female lung cancer deaths were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. The control group included women who died from nonneoplasms and diseases that were not associated with respiratory problems. We pair-matched the controls to the cases by sex, year of birth, and year of death. Each matched control was selected randomly from the set of possible controls for each case. We used the proportion of a municipality's total population employed in the petrochemical manufacturing industry as an indicator of a resident's exposure to air emissions from the petrochemical manufacturing industry. The subjects were divided into tertiles according to the above indicator. Women who lived in the 2 groups of municipalities characterized by higher levels of petrochemical pollution had a statistically significant higher risk of developing lung cancer than the group that lived in municipalities with the lowest petrochemical air pollution levels (after controlling for possible confounders). The linear trend was also statistically significant (p < .05). The results of this study shed important light on the relationship between the Taiwan petrochemical industry and the resulting risk to human health.

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