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

Our plain-English summary of Epidemiology study of the use of asbestos-cement pipe for the distribution of drinking water in Escambia County, Florida, by J.R. Millette, G.F. Craun, J.A. Stober, et al (Environmental Health Perspectives, 1983).

The study

• Authors: J.R. Millette, G.F. Craun, J.A. Stober, D.F. Kraemer, H.G. Tousignant, E. Hildago, R.L. Duboise, J. Benedict
• Journal: Environmental Health Perspectives
• Published: 1983;53:91-8
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000632).

Abstract

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.

In plain English

This study compared cancer deaths in census tracts of Escambia County, Florida, where drinking water ran through asbestos-cement (AC) pipe, with tracts served by cast iron pipe or private wells. Some home water samples from AC-pipe areas contained asbestos fibers (amphibole and chrysotile), and dug-up pipe was releasing fibers. Changing water treatment meant past exposure could not be estimated from these measurements. Instead, 36 tracts were grouped into potential high, low and no exposure based on how much AC pipe they had and how long it had been used. Death certificates from 1963 to 1976 were reviewed, and death rates for seven cancer sites were compared after adjusting for socioeconomic and population factors. No cancer site differed significantly between the groups. The authors concluded that, within the study's limited sensitivity, they found no evidence of an association between AC pipe and gastrointestinal and related cancers. They noted that they could not account for smoking, occupation or alcohol, that about half the people had moved within five years, and that even a 300% increase in kidney, bladder or liver cancer would not have been detected.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Census-tract-level comparison of cancer death rates (standard mortality ratios from death certificates, 1963 to 1976) across three potential exposure groups, analysed by analysis of covariance with socioeconomic and population factors as covariates
• Who was studied: Residents of Escambia County, Florida (a little over 200,000 people in 40 census tracts). Four tracts (total population 20,936) were excluded. The remaining 36 tracts were grouped as potential high exposure (9 tracts, population 46,123), low exposure (13 tracts, 86,897) and no exposure (14 tracts, 51,378), using 1970 census populations.
• Exposure: Asbestos fibers released into drinking water from asbestos-cement distribution pipe (thought to be type II pipe). Tracts were grouped by amount and age of AC pipe. High exposure meant at least 90% of the population had been served by AC pipe for 25 years or more by 1976. Low exposure meant less coverage or younger pipe. No exposure meant cast iron pipe or private wells. Water samples were tested for amphibole and chrysotile fibers.
• Main results:
  • Some home water samples from census tracts using AC pipe showed measurable asbestos concentrations and others did not.
  • In the Montclair system, inspection of excavated pipe confirmed that the pipe was releasing fibers.
  • For none of the cancer sites studied did death rates differ significantly (p less than 0.05) between the high, low and no exposure tract groups.
  • The authors estimated that the study should have been able to detect a 70% increase in gastrointestinal cancer deaths in the high exposure group compared with the no exposure group.
  • For kidney, bladder or liver cancer, deaths were too few for even a 300% increase to have been identified as statistically significant.
• The authors' conclusion: The authors concluded that, to the level of sensitivity allowed by the study's limitations, they found no evidence for an association between the use of AC pipe for drinking water and deaths from gastrointestinal and related cancers in Escambia County.
• Limitations the authors state:
  • The study could not assess individual factors such as smoking, occupation and alcohol consumption.
  • Changing water treatment practices meant fiber measurements could not be used to estimate past exposures.
  • Some cancers, such as kidney cancer, had very few deaths. 75% of tracts had no kidney cancer deaths over the 14 years.
  • Exposure groups were grouped geographically, and whether this caused confounding could not be assessed.
  • About half the population had moved within five years, which casts doubt on this type of study for diseases with long latency periods.
  • The extra cancers predicted by an EPA water quality risk estimate would not have been detectable in this study.

Topics

Medical terms in this study, explained in our Lexicon: Epidemiology, Asbestos-Cement Pipe, Asbestos-Cement, Asbestos Exposure.

Related studies

• The use of asbestos-cement pipe for public water supply and the incidence of cancer in selected communities in Utah — T.D. Sadler, W.N. Rom, et al. (1984)
• Is there a risk to health in using asbestos--cement pipes for the carriage of drinking water? — S.F. McCullagh (1980)
• The San Francisco Bay epidemiology studies on asbestos in drinking water and cancer incidence: relationship to studies in other locations and pointers for further research — M.S. Kanarek (1983)
• An investigation of the use of asbestos cement pipe for public water supply and the incidence of gastrointestinal cancer in Connecticut, 1935-1973 — J.M. Harrington, G.F. Craun, et al. (1978)
• Cancer incidence in relation to asbestos in drinking water in the Puget Sound region — L. Polissar, R.K. Severson, et al. (1982)
• A case-control study of asbestos in drinking water and cancer risk — L. Polissar, R.K. Severson, et al. (1984)

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