Mortality among autoworkers manufacturing electronics in Huntsville, Alabama

Our plain-English summary of Mortality among autoworkers manufacturing electronics in Huntsville, Alabama, by N. DeBono, K. Kelly-Reif, D. Richardson, et al (American Journal of Industrial Medicine, 2019).

The study

• Authors: N. DeBono, K. Kelly-Reif, D. Richardson, A. Keil, W. Robinson, M. Troester, S. Marshall
• Journal: American Journal of Industrial Medicine
• Published: 2019;62(4):282-295
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Workers raised concerns over suspected excesses of mortality at automotive electronics manufacturing facilities in Huntsville, Alabama.

Methods: A study of 4396 UAW members ever-employed at Huntsville facilities between 1972 and 1993 was conducted with mortality follow-up through 2016. Standardized Mortality Ratios (SMRs) were estimated using U.S. and Alabama reference rates.

Results: Relative to U.S. rates, there was a modest excess of all-cause mortality among White female workers (SMR 1.08, 95%CI: 0.99-1.18) and among all workers hired <1977 at the original plant building (SMR 1.10, 95%CI: 0.99-1.22). There was excess nervous system disorder (SMR 1.24, 95%CI: 0.91-1.65) and brain and nervous system cancer (SMR 1.31, 95%CI: 0.67-2.28) mortality. Estimates for several causes of interest were imprecise.

Conclusions: All-cause mortality estimates were greater than anticipated based on results from other UAW cohorts. The excess of nervous system disease mortality is consistent with other studies of electronics workers exposed to lead-solder and chlorinated solvents.

© 2018 Wiley Periodicals, Inc.

In plain English

This study followed 4396 United Autoworkers (UAW) members who worked at Chrysler electronics plants in Huntsville, Alabama, between 1972 and 1993, with deaths counted through 2016. Former workers named lead, chlorinated solvents, fiberglass dust, conformal coatings and asbestos as exposures of concern. No exposure measurements were available. Deaths were compared with U.S. and Alabama population rates. All-cause deaths were similar to U.S. rates (SMR 1.01, 95% CI 0.95-1.07). Small excesses appeared among White female workers (SMR 1.08, 95% CI 0.99-1.18) and workers first hired before 1977 (SMR 1.10, 95% CI 0.99-1.22). Compared with U.S. rates, nervous system disorder deaths (46, SMR 1.24, 95% CI 0.91-1.65) were above expected, which the authors called close to statistical significance. Brain and nervous system cancer deaths (12, SMR 1.31, 95% CI 0.67-2.28) were also above expected, but this estimate was imprecise. Lung cancer deaths (96) were close to expected, and there was one asbestosis death. The authors concluded that the nervous system findings were consistent with studies of workers exposed to lead and chlorinated solvents. They also reported evidence of asbestos exposure of unknown prevalence and source.

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: Occupational cohort mortality study comparing observed deaths with deaths expected from U.S. and Alabama general population rates (standardized mortality ratio analysis)
• Who was studied: 4396 hourly and salaried UAW members employed for any length of time at Chrysler electronics facilities in Huntsville, Alabama, between 1972 and 1993. Vital status was followed to December 5, 2016. The cohort was 58% female and 80% White among those with known race. 1134 (26%) had died.
• Exposure: Work making automotive electronic circuit boards. Interviews with former workers identified these exposures of concern: lead (solder), chlorinated solvents (including TCE and 1,1,1-trichloroethane), fiberglass dust, conformal coatings, and asbestos (reported in plant walls; fiber type not stated). No quantitative exposure or industrial hygiene data, and no job- or department-specific work histories, were available.
• Main results:
  • Whole cohort, compared with U.S. rates: all-cause mortality was similar to expected (SMR 1.01, 95% CI 0.95-1.07).
  • White female workers, compared with U.S. rates: small excess of all-cause mortality (SMR 1.08, 95% CI 0.99-1.18).
  • Workers first hired before 1977 (n = 905), compared with U.S. rates: 379 deaths from all causes, SMR 1.10 (95% CI 0.99-1.22).
  • Whole cohort, compared with U.S. rates: excess of deaths from nervous system disorders (46 deaths, SMR 1.24, 95% CI 0.91-1.65).
  • The authors described the nervous system disorder estimate for the overall cohort as precise and close to statistical significance.
  • Whole cohort, compared with U.S. rates: deaths from cancer of the brain and nervous system were elevated but imprecise (12 deaths, SMR 1.31, 95% CI 0.67-2.28).
  • Whole cohort, compared with U.S. rates: 96 deaths from cancer of the trachea, bronchus and lung against 101.3 expected (SMR 0.95, 95% CI 0.77-1.16).
  • Whole cohort, compared with U.S. rates: 1 death from asbestosis against 0.2 expected (SMR 5.61, 95% CI 0.14-31.3).
  • The authors reported evidence of asbestos exposure in the cohort, but the prevalence and source of this exposure were unknown.
  • Whole cohort, compared with U.S. rates: excess of deaths from cardiac conduction disorders (66 deaths, SMR 3.74, 95% CI 2.89-4.76). This excess disappeared when Alabama rates were used (SMR 0.98, 95% CI 0.76-1.25).
  • The authors considered the cardiac conduction disorder excess likely to be the result of cause-of-death coding practices in Alabama.
  • Whole cohort, compared with Alabama rates: all-cause mortality was lower than expected (SMR 0.83, 95% CI 0.78-0.88).
  • The authors stated that the results suggest all-cause mortality in this cohort was greater than in other large UAW cohorts.
• The authors' conclusion: The authors concluded that the cohort had elevated mortality from brain and nervous system cancers and from nervous system disorders relative to U.S. rates. They considered this consistent with previous studies of workers occupationally exposed to lead and chlorinated solvents.
• Limitations the authors state:
  • There was no exposure assessment, so the prevalence and intensity of exposures were unknown.
  • Job- or department-specific work histories were not available, and hourly workers could not be separated from salaried workers.
  • Only deaths were studied, not disease incidence, so the burden of less often fatal diseases was underestimated.
  • Because the cohort was relatively small, estimates for several causes of interest were imprecise, especially in stratified analyses.
  • Some cause-specific estimates may have been biased downward by 'healthy worker' effects.
  • Misclassification of cause of death, particularly deaths possibly misclassified as cardiovascular in Alabama, may have biased estimates for other causes downward.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Auto mechanics and brake work, Throat and laryngeal cancer.

Medical terms in this study, explained in our Lexicon: standardized mortality ratio (SMR).

Related studies

• Employment characteristics and cause-specific mortality at automotive electronics manufacturing plants in Huntsville, Alabama — N. DeBono, D. Richardson, et al. (2019)
• Mortality from non-malignant respiratory disease in the fibreglass manufacturing industry — L. Chiazze, D.K. Watkins, et al. (2002)
• Cancer mortality in a population exposed to nephrite processing — H.Y. Yang, S.H. Huang, et al. (2016)
• Mortality patterns among electrical workers employed in the U.S. construction industry, 1982-1987 — C.F. Robinson, M. Petersen, et al. (1999)
• Extended Mortality Follow-up of a Cohort of 25,460 Workers Exposed to Acrylonitrile — S. Koutros, J.H. Lubin, et al. (2019)
• Mortality among workers at the Savannah River Site — D.B. Richardson, S. Wing, et al. (2007)

Browse more research in American Journal of Industrial Medicine, or return to medical research.