Mortality experience of amosite asbestos factory workers: dose-response relationships 5 to 40 years after onset of short-term work exposure

Our plain-English summary of Mortality experience of amosite asbestos factory workers: dose-response relationships 5 to 40 years after onset of short-term work exposure, by H. Seidman, I.J. Selikoff, S.K. Gelb (American Journal of Industrial Medicine, 1986).

The study

• Authors: H. Seidman, I.J. Selikoff, S.K. Gelb
• Journal: American Journal of Industrial Medicine
• Published: 1986;10(5-6):479-514
• Cited by: 119 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000434).

Abstract

A cohort of 820 men in a Paterson, New Jersey, amosite asbestos factory which began work during 1941-1945 was observed from 5 to 40 years after start of work. Most of the cohort had limited duration of work experience (days, weeks, months), though some men worked for several years until the factory closed in 1954. With white males of New Jersey as the control population, Standardized Mortality Ratios (SMRs) of 500 are evident for the cohort for lung cancer and for noninfectious pulmonary diseases (including asbestosis), while being almost 300 for total cancer and about 170 for all causes of death. A statistically significant SMR of almost 200 is seen for colon-rectum cancer. Mesothelioma incidence initially shows a strong relationship with advancing time since onset of exposure and then tails off. The main concern of the study is with dose-response patterns. Response is measured by the mortality for relevant causes of death, while the direct asbestos dosage was measured in two ways. One way was the length of time worked in the factory and the other was the individual's accumulated fiber exposure, calculated by multiplying the aforementioned length of time worked by the estimated fiber exposures associated with the particular job that the worker had in the factory. Whichever measure of dosage is used, it was found that, in general, the lower the dose, the longer it took for adverse mortality to become evident and, also, the smaller the magnitude of that adverse mortality.

In plain English

This study followed 820 men who began work between 1941 and 1945 at an amosite asbestos factory in Paterson, New Jersey. Many worked there only days, weeks or months. The authors compared the men's deaths from 5 to 40 years after they started work, through 1982, with death rates of New Jersey white men. By the end of follow-up, 593 men had died, against 355.87 deaths expected (standardized mortality ratio 167). Lung cancer deaths were about five times the expected number (111 observed, 20.51 expected), as were deaths from noninfectious lung diseases including asbestosis. Deaths from all cancers were almost three times the expected number. There were 8 pleural and 9 peritoneal mesothelioma deaths. Dose was measured two ways: as time worked, and as estimated fiber-years. No fiber counts existed for this factory, so the estimates used counts taken in 1967, 1970 and 1971 at two sister plants. Among longer-term workers, marked lung cancer excesses appeared within 15 years; for shorter-term workers it could take 25 years or more. The authors concluded that, by either measure, lower doses were followed by later and smaller excesses in deaths.

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: Cohort mortality study (follow-up of a factory workforce). Observed deaths were compared with expected deaths using standardized mortality ratios (SMRs) and life-table methods. This report extends the authors' earlier report on the same cohort.
• Who was studied: 933 men were recruited from June 1941 through December 1945 to an amosite asbestos factory in Paterson, New Jersey. 113 were excluded (21 had prior asbestos work, 14 took up asbestos work elsewhere before the five-year point, 40 had died, and 38 were lost to follow-up), leaving 820 men. They were followed from 5 to 40 years after starting work, through December 31, 1982. The initial group was almost entirely white. Comparison group: general white male population of New Jersey.
• Exposure: Amosite asbestos, used virtually exclusively; no crocidolite and very little chrysotile. Products were pipe covering, sheets, mattresses, blocks and asbestos rope. There were no direct fiber counts in the factory. Job-specific estimates (5 to 120 fibers longer than 5 micrometers per cc; median 50) were assigned using U.S. Public Health Service counts from 1967, 1970 and 1971 at the company's Tyler, Texas, and Port Allegheny, Pennsylvania, plants. Dose was measured as length of time worked and as fiber-years per cc (range 0.1 to 1,170.0; median 21.0).
• Main results:
  • Whole cohort, 5 to 40 years after onset of work: all causes 593 observed vs 355.87 expected (SMR 167). All cancers 213 vs 74.19 (SMR 287). Lung cancer 111 vs 20.51 (SMR 541, best-evidence coding). Noninfectious pulmonary diseases 46 vs 9.40 (SMR 489). All p less than 0.001.
  • Colon-rectum cancer in the whole cohort: 22 observed vs 11.90 expected (SMR 185), statistically significant at p less than 0.05.
  • Mesothelioma (best-evidence coding): 8 pleural and 9 peritoneal deaths. Expected numbers were not available, so rates per million man-years were shown. Rates rose in the 20-24, 25-29 and 30-34 year periods after onset of work and fell off in the 35-39 year period, which the authors suggested was perhaps partly due to earlier deaths from other asbestos-associated diseases.
  • Lung cancer by length of time worked: marked excesses appeared within 15 years among longer-term workers, while for shorter-term workers it could take 25 years or more. Over 5 to 39 years, men who worked 2+ years had 43 lung cancer deaths vs 4.38 expected (SMR 983). Men who worked less than 1 month had 6 vs 2.38 (SMR 252, not marked as statistically significant).
  • By estimated fiber exposure, the patterns were generally similar to those for time worked. For lung cancer over 5 to 39 years: under 6.0 fiber-years per cc, 15 observed vs 5.31 expected (SMR 282); 250.0+ fiber-years per cc, 15 vs 0.94 (SMR 1,596).
  • Within the same fiber-exposure category, there was a very slight tendency toward higher lung cancer SMRs for men who worked longer at lower-exposure jobs than for men who worked shorter times at higher-exposure jobs.
• The authors' conclusion: The authors concluded that, whether dose was measured as length of time worked or as estimated fiber exposure, much the same dose-response pattern appeared: in general, the lower the dose, the longer adverse mortality took to become evident and the smaller it was. They stated that reducing exposure might delay adverse effects and lower their frequency. They also stated that, especially with lighter or shorter exposure, prolonged follow-up is necessary.
• Limitations the authors state:
  • There were no direct fiber count measurements in the Paterson factory. Exposures were estimated from counts at two other plants of the same company, where general conditions may have been somewhat better.
  • The fiber estimates may be somewhat high, because industrial hygienists tend to over-sample dustier areas. Any overestimate would also overstate the dose linked to the disease responses observed.
  • Shorter-term workers may have received a higher dose per unit of time than longer-term workers, because of apprenticeship periods doing dirtier work.
  • Whether the general population is a suitable comparison for factory workers is open to question. New Jersey cancer rates are among the highest in the United States.
  • Expected deaths could not be calculated for mesothelioma and asbestosis, because these are very uncommon in the general population.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Amosite.

Medical terms in this study, explained in our Lexicon: Amosite, Dose-response relationship, standardized mortality ratio (SMR), Lung Cancer, Mesothelioma.

Related studies

• Long term radiological effects of short term exposure to amosite asbestos among factory workers — R. Ehrlich, R. Lilis, et al. (1992)
• Short-term asbestos work exposure and long-term observation — H. Seidman, I.J. Selikoff, et al. (1979)
• Mortality experience of family contacts of asbestos factory workers — L. Joubert, H. Seidman, et al. (1991)
• Quantification of the pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite-asbestos following short-term inhalation exposure — D.M. Bernstein, R.A. Rogers, et al. (2011)
• The pathological response and fate in the lung and pleura of chrysotile in combination with fine particles compared to amosite asbestos following short-term inhalation exposure: interim results — D.M. Bernstein, R.A. Rogers, et al. (2010)
• Final results from a 90-day quantitative inhalation toxicology study evaluating the dose-response and fate in the lung and pleura of chrysotile-containing brake dust compared to TiO2, chrysotile, crocidolite or amosite asbestos: Histopathological examination, confocal microscopy and collagen quantification of the lung and pleural cavity — D.M. Bernstein, B. Toth, et al. (2021)

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