Drinking Water and Health, Volume 3 (1980) / Chapter Skim
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II Epidemiological Studies
II Epidemiological Studies
Pages 5-24
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From page 5... ...
also studied the biological effects of chloroform in its large animal bioassay program and subsequently demonstrated an increase in liver and kidney tumors among animals exposed to high doses of chloroform (Page and Saffioti, 1976~. Given these several pieces of information, the EPA asked a number of research groups to detains whether there was indeed a relationship between cancer rates and chloroform and other THM's in water supplies.
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From page 6... ...
For example, for bladder cancer one needs to control for occupation' cigarette smoking, use of alcohol and drugs, nonaqueous sources of THM, coffee consumption, socioeconomic status, and ethnicity. The studies also had to assume that present exposures to THM reflected lifetime exposures of the populations studied: this is not only because THM concentrations in water have only recently been measurable, but also because the necessary information on migration patterns with associated THM concentrations is not readily available.
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found regression coefficients of bladder cancer mortality (deaths/105/year) on chloroform concentration (,ug/liter)
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Significant positive correlation coefficients were found in two of the four race-sex groups for genitourinary cancer, and in all four groups for gastrointestinal cancer. MISSISSIPPI RIVER-LOUISIANA, SECOND STUDY Using the same water quality data and county mortality data as Harris (1974, unpublished)
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From page 9... ...
and the pancreas in males. They studied the effect of water source on cancer mortality by regression analysis similar to that used in the first Ohio area study.
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and urinary tract tUT] cancer mortality than are individuals living in nonchlonnated water areas.
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correlated cancer mortality rates and incidence rates with chloroform content in drinking water. They divided the county into nine subareas categorized as having low, medium, or high chloroform content of the water.
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studied all 21 counties in New Jersey to determine the relation between water source and ageadjusted cancer mortality from lung' stomach, and urinary tract cancer of white males between 1950 and 1969. Water quality was estimated from the ratio of the number of households served by public systems and private water companies to the number served by individual wells.
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All three studies used cancer mortality data rather than incidence data. Although incidence data are usually preferable, the studies could not use these data as they are not generally available for the areas covered by the THM surveys.
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14 .5 a' _1 Ct o Cal U
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16 o 3 ~2 g .~ .ou cn g ._ .~ ca ~n o U)
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From page 17... ...
The data are consistent with an increase in cancer rates of the rectum, the bladder, and possibly the large intestine with increased chloroform concentration. McCabe showed that age-adjusted total cancer mortality rates correlated positively with estimated chloroform concentrations in 80 cities.
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PROSPECTS FOR FURTHER EPIDEMIOLOGICAL STUDY Adequate exploratory and hypothesis-generating work has been done. Studies raising suspicion of higher cancer rates among persons whose major water supplies came from surface waters with generally higher THM concentrations compared to rates among those whose major water sources were groundwaters have been followed by attempts to relate the cancer rates to actual THM concentrations.
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From page 19... ...
Similarly, if there is no association, large populations must be studied to exclude the existence of the small effects that have been postulated. Some useful data may be available from foreign countries and the help of international agencies (World Health Organization-International Agency for Research on Cancer, North Atlantic Treaty Organization, U.S.-Japan Scientific Exchange, U.S.-USSR Scientific Exchange)
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1978. Association Between Chloroform Levels in Finished Dnnking Water Supplies and Vanous Site-Specific Cancer Mortality Rates.
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32 pp. WATER HARDNESS AND CARDIOVASCULAR DISEASE The Present Status of Knowledge The following statement regarding water "hardness" appears in Drinking Water and Health (National Academy of Sciences, 1977)
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From page 22... ...
A few contain sufficient data for risk estimation: upper estimates of risk ratios for soft compared to hard water average approximately 1.25 for cardiovascular disease and 1.2 for arteriosclerotic, stroke, and hypertensive diseases CNational Academy of Sciences!
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Some of these opportunities for studies could, with relatively little expenditure, be turned into very useful controlled prospective epidemiological studies if sufficient time is available for careful planning of control populations and maintenance of migration records. The results of clinical research from two types of studies may provide useful information on the relationship of water hardness and cardiovas
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From page 24... ...
Controlled trials of magnesium supplements (as fortified food or tablets) with groups of individuals at high risk of cardiovascular disease could also provide useful information.
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