Asbestos in drinking water and cancer in the San Francisco bay area: 1969–1974 incidence

This report is an assessment of all available literature that pertains to the potential risk of cancer associated with ingestion of asbestos. It was compiled by a working group to assist policy makers in the Department of Health and Human Services determine if adequate information was available for a definitive risk assessment on this potential problem and evaluate if the weight of evidence was sufficient to prioritize this issue for new policy recommendations. The work group considered the basis for concern over this problem, the body of toxicology experiments, the individual epidemiologic studies which have attempted to investigate this issue, and the articles that discuss components of risk assessment pertaining to the ingestion of asbestos. In the report, the work group concluded: 1) that no direct, definitive risk assessment can be conducted at this time; 2) that further epidemiologic investigations will be very costly and only possess sufficient statistical power to detect relatively large excesses in cancers related to asbestos ingestion; and 3) that probably the most pertinent toxicologic experiments relate to resolving the differences in how inhaled asbestos, which is eventually swallowed, is biologically processed by humans, compared to how ingested asbestos is processed. The work group believes that the cancer risk associated with asbestos ingestion should not be perceived as one of the most pressing potential public health hazards facing the nation. However, the work group does not believe that information was sufficient to assess the level of cancer risks associated with the ingestion and therefore, this potential hazard should not be discounted, and ingestion exposure to asbestos should be eliminated whenever possible.

Section: Bay Area Californiamentioning

confidence: 89%

“…A number of epidemiologic evaluations conducted in seven areas of the United States and Canada examined the association between drinking water supplies containing asbestos and cancer mortality (8,(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54).…”

Section: Epidemiologymentioning

confidence: 99%

Report on cancer risks associated with the ingestion of asbestos. DHHS Committee to Coordinate Environmental and Related Programs

1987

“…These factors have been discussed in previously published studies of the same type that considered exposure to asbestos in drinking water (12,13). The R2 values, which indicated that less than 25% of the variation between exposure groups was accounted for by the general census tract level factors considered, were similar to the R2 values of the other studies (11)(12)(13). Only the composite factor 4 showed a regression coefficient significantly different from zero for any sites (p < 0.05).…”

Section: Discussionmentioning

confidence: 99%

Epidemiology study of the use of asbestos-cement pipe for the distribution of drinking water in Escambia County, Florida.

Millette¹,

Craun²,

Stober³

et al. 1983

Cancer mortality for the population census tracts of Escambia County, FL, which use asbestos-cement (AC) pipe for public potable water distribution, was compared with cancer mortality data collected from census tracts in the same county where other types of piping materials are used. An analysis of covariance was run to test for differences in standard mortality ratios for seven cancer sites among three potential asbestos exposure groups based on AC pipe usage. Twelve variables representing nonexposure-related influences on disease rates were combined in four independent factors and used as covariates in these analyses. No evidence for an association between the use of AC pipe for carrying drinking water and deaths due to gastrointestinal and related cancers was found. The limitations on the sensitivity of the analysis are discussed.

“…Cancer incidence between 1969 and 1971 was analyzed in the initial study and has been reported by Kanarek et al (1). A second study of cancer incidence between 1969 and 1974 was carried out and published by Conforti et al (2). The present work is a reanalysis of the 6-yr data base (1969)(1970)(1971)(1972)(1973)(1974) to determine the effect of population density on the observation of an association between ingested asbestos and cancer.…”

Section: Introductionmentioning

confidence: 92%

Effect of population density on the results of the study of water supplies in five California counties.

Conforti¹

1983

Two previous studies (1969-1971 and 1969-1974) examined the association between cancer incidence and chrysotile asbestos ingested through drinking water in the San Francisco-Oakland Standard Metropolitan Statistical Area (SMSA). Population density, an important covariable in the association between cancer and environmental agents, was not included in the analyses of these studies. The present work determines the effect of this covariable on the results of the second San Francisco-Oakland SMSA study. The original and reanalyzed results are compared to reassess the association between cancer and asbestos. The only change in the regression procedures of the original studies was the addition of population density as an independent variable in the reanalysis. The results of the reanalysis showed that population density had little effect on the results of the second study. Slightly more significance was found for asbestos regression coefficients in the reanalysis, including population density, than in the original analysis. These regression coefficients for asbestos indicated a positive association between ingested chrysotile asbestos and some cancer body sites. The conclusion of the reanalysis was that population density was distributed across the San Francisco-Oakland SMSA in such a way that it had little effect on the observation of an association between ingested asbestos and cancer.