Evaluation of contaminated drinking water and male breast cancer at Marine Corps Base Camp Lejeune, North Carolina: a case control study

Our plain-English summary of Evaluation of contaminated drinking water and male breast cancer at Marine Corps Base Camp Lejeune, North Carolina: a case control study, by P.Z. Ruckart, F.J. Bove, E. Shanley, et al (Environmental Health, 2015).

The study

• Authors: P.Z. Ruckart, F.J. Bove, E. Shanley, M. Maslia
• Journal: Environmental Health
• Published: 2015;14:74
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Solvents contaminated drinking water supplies at Marine Corps Base Camp Lejeune during 1950s-1985.

Methods: We conducted a case-control study among Marines to evaluate associations between residential exposure to contaminated drinking water at Camp Lejeune and male breast cancer risk. The study included 71 male breast cancer cases and 373 controls identified from the Department of Veteran's Affairs (VA) cancer registry whose military personnel records were available. Controls were selected from cancers not known to be associated with solvent exposure and included 270 skin cancers, 71 mesotheliomas, and 32 bone cancers. Base assignment and risk factor information came from military personnel and VA records. Groundwater contaminant fate/transport and distribution system models provided monthly estimated residential contaminant levels. We conducted exact logistic regression using the 50th percentile level among exposed controls to create low and high exposure categories. We calculated 95% confidence intervals (CIs) to indicate precision of effect estimates. Exploratory analyses used proportional hazards methods to evaluate associations between exposures and age at diagnosis.

Results: After adjusting for age at diagnosis, race, and service in Vietnam, the odds ratio (OR) for ever stationed at Camp Lejeune was 1.14 (95% CI: 0.65, 1.97). Adjusted ORs for high residential cumulative exposures to tetrachloroethylene (PCE), t-1,2 dichloroethylene (DCE), and vinyl chloride were 1.20 [95% CI: 0.16-5.89], 1.50 [95% CI: 0.30-6.11], 1.19 [95% CI: 0.16-5.89], respectively, with a monotonic exposure response relationship for PCE only. However these results were based on two or three cases in the high cumulative exposure categories. Ever stationed at Camp Lejeune and high cumulative exposures to trichloroethylene (TCE), PCE, DCE and vinyl chloride were associated with earlier age at onset for male breast cancer; hazard ratios ranged from 1.4-2.7 with wide confidence intervals for cumulative exposure variables.

Conclusion: Findings suggested possible associations between male breast cancer and being stationed at Camp Lejeune and cumulative exposure to PCE, DCE, and vinyl chloride. TCE, PCE, DCE and vinyl chloride cumulative exposures showed possible associations with earlier age at onset of male breast cancer. However, this study was limited by small numbers of cases in high exposure categories.

In plain English

This case-control study asked whether residential exposure to contaminated drinking water at Marine Corps Base Camp Lejeune, North Carolina, was associated with male breast cancer. Solvents contaminated the water from the 1950s until 1985. It is not a study of asbestos. Pleural and peritoneal mesothelioma appeared only among the controls, which were chosen as cancers not known to be linked to solvents. From the Veterans Affairs cancer registry, the authors compared 71 Marines with male breast cancer to 373 with skin cancer, mesothelioma or bone cancer. For men stationed there, water models of the base's supply gave estimated residential exposure to tetrachloroethylene (PCE), trichloroethylene (TCE), t-1,2 dichloroethylene (DCE), vinyl chloride and benzene. For ever being stationed at Camp Lejeune, the adjusted odds ratio was 1.14 (95% CI 0.65 to 1.97). Compared with no residential exposure, adjusted odds ratios for high cumulative exposure were 1.20 (95% CI 0.16 to 5.89) for PCE, 1.50 (0.30 to 6.11) for DCE and 1.19 (0.16 to 5.89) for vinyl chloride. Each rested on two or three cases. Exploratory analyses linked several exposures to earlier age at diagnosis. The authors concluded the findings suggested possible associations but were limited by small numbers.

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: Case-control study using registry and military personnel records (data linkage, no interviews), with exploratory proportional hazards analyses of age at diagnosis
• Who was studied: Male Marines born before January 1, 1969, diagnosed with or treated for cancer at a VA medical facility from January 1, 1995 to May 5, 2013. There were 71 male breast cancer cases and 373 controls: 270 skin cancers, 67 mesotheliomas of the pleura, 32 bone cancers and 4 mesotheliomas of the peritoneum. Controls were drawn from cancers not known to be associated with solvent exposure.
• Exposure: Residential exposure to drinking water at Camp Lejeune contaminated with volatile organic compounds: TCE, PCE, t-1,2 dichloroethylene (DCE), vinyl chloride and benzene. Historical water modeling estimated monthly contamination levels in the base's water systems. These estimates were combined with personnel and housing records to assign residential exposure levels to cases and controls who were stationed at Camp Lejeune. Marines residing off-base, or in base housing with uncontaminated water, were counted as unexposed. Cumulative exposure was measured in ppb-months and split into low and high categories at the median among exposed controls. Being stationed at the base was analyzed separately. Asbestos was not studied.
• Main results:
  • Marines ever stationed at Camp Lejeune were compared with those never stationed there. The unadjusted OR was 1.45 (95% CI 0.86-2.44). The OR adjusted for age at diagnosis, race and service in Vietnam was 1.14 (95% CI 0.65-1.97 in the abstract and Table 3; the Results text gives 0.65-1.98). 30 of 71 cases and 125 of 373 controls had been stationed there.
  • Compared with no residential exposure to that contaminant, adjusted ORs for high cumulative exposure were 1.20 (95% CI 0.16-5.89) for PCE, 1.50 (95% CI 0.30-6.11) for DCE and 1.19 (95% CI 0.16-5.89) for vinyl chloride. A monotonic exposure-response relationship was seen for PCE only.
  • The high-exposure adjusted ORs for PCE and vinyl chloride were each based on two cases. The one for DCE was based on three cases.
  • For high cumulative exposure to TCE, benzene and TVOC (the sum of all contaminants), unadjusted ORs were above 1.00. The authors report that the adjusted results were not elevated.
  • For living 38 weeks or more in a residence receiving contaminated water, the adjusted OR was 0.89 (95% CI 0.38-1.93).
  • In the exploratory analyses of age at diagnosis, Marines ever stationed at Camp Lejeune had an adjusted hazard ratio of 1.51 (95% CI 0.78-2.95).
  • Adjusted hazard ratios for high cumulative exposure were 2.08 (95% CI 0.31-14.00) for PCE, 1.41 (0.58-3.46) for TCE, 2.72 (0.52-14.18) for DCE and 2.14 (0.31-14.81) for vinyl chloride.
  • The authors found no evidence suggesting associations with benzene or with the combined measure of all contaminants.
• The authors' conclusion: The authors concluded that the high-exposure ORs for PCE, DCE and vinyl chloride suggest possible associations with male breast cancer. In the exploratory analyses, these exposures and TCE possibly accelerated onset. The study was limited by small numbers of exposed cases, and the authors said additional research is needed.
• Limitations the authors state:
  • Small numbers of exposed cases, resulting in wide confidence intervals.
  • Seven cases could not be included because the authors had no information on where they were stationed.
  • Only a minority of veterans use VA care, so cases were likely undercounted and the sample size was limited.
  • Some contaminants were correlated (e.g., PCE, DCE and vinyl chloride), making their effects hard to separate.
  • Exposure was assigned by place of residence, without interviews about activities such as field training, so exposure misclassification was probable.
  • There was no information on some risk factors, so unmeasured confounding is possible.

Topics

Medical terms in this study, explained in our Lexicon: Case-Control Study, Cancer Registry, Mesothelioma, confidence interval, Odds Ratio, Cumulative Exposure, Hazard Ratio.

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