Mesothelioma incidence and community asbestos exposure

Our plain-English summary of Mesothelioma incidence and community asbestos exposure, by M. Berry (Environmental Research, 1997).

The study

• Author: M. Berry
• Journal: Environmental Research
• Published: 1997;75(1):34-40
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This study evaluates the environmental, nonoccupational component of mesothelioma incidence among persons living in Manville, Somerset County, New Jersey, the location of the largest asbestos manufacturing plant in North America. Prior to removal of occupational cases, residents of Manville had an average annual (1979-1990) mesothelioma rate of 636 male cases and 96 female cases per million population, about 25 times higher than average state rates. Somerset County had 143 diagnosed mesothelioma cases reported to the population-based. New Jersey State Cancer Registry from 1979 through 1990. Cases were removed from the analysis when their "usual employment" was reported as being at the asbestos plant, as evidenced through union lists or occupational information from either the Cancer Registry or mortality records. Standardized incidence ratios (SIRs) were computed for residents of Manville and Somerset County (less the Manville population) by sex. New Jersey mesothelioma rates less the Somerset County contribution, 1979-1990, were used to generate the expected number of cases. The SIRs for Manville males and females were respectively 10.1 [95% confidence interval (CI): 5.8-16.4] and 22.4 (95% CI: 9.7-44.2). Male and female Somerset County mesothelioma incidence rates were 1.9 (95% CI: 1.4-2.5) and 2.0 (95% CI: 1.0-3.6). This record-based approach demonstrates a strong relationship between past asbestos exposure from living in Manville and eventual development of mesothelioma. The use of methods in this study may be helpful in evaluating hazards of other known occupational carcinogens found in community settings.

In plain English

This study used the New Jersey State Cancer Registry to examine mesothelioma (pleural and peritoneal combined) diagnosed from 1979 through 1990 among residents of Somerset County, New Jersey. Manville, in that county, was the site from 1912 to 1980 of the largest asbestos products plant in North America, which used primarily chrysotile asbestos. Of 143 county cases, 61 were identified through death certificates, a union list or registry records as having worked at the plant and were removed, leaving 82. Compared with state rates excluding Somerset County, Manville residents not identified as plant workers had a standardized incidence ratio of 10.1 (95% CI 5.8–16.4) for males (16 observed, 1.6 expected) and 22.4 (9.7–44.2) for females (8 observed, 0.4 expected). In the rest of Somerset County the ratios were 1.9 (1.4–2.5) for males and 2.0 (1.0–3.6) for females. The author concluded that Manville residents had an extremely elevated risk. The author noted that full job histories were not collected, so some cases may have worked at the plant, and that cases from airborne contamination and household contact could not be separated.

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: Record-based incidence study using a population-based cancer registry, with standardized incidence ratios (observed versus expected cases) compared against state rates
• Who was studied: Residents of Somerset County, New Jersey, with newly diagnosed mesothelioma (pleural and peritoneal) reported to the New Jersey State Cancer Registry, 1979 through 1990. There were 143 county cases (122 males, 21 females), 55 of them Manville residents (46 males, 9 females). After removing 61 cases identified as plant workers, 82 cases remained (63 males, 19 females): 24 living in Manville and 58 elsewhere in the county. Comparison rates came from New Jersey minus Somerset County.
• Exposure: Living in Manville (the 'exposed' group) or elsewhere in Somerset County (the 'lower exposed' group) at the time of diagnosis. Manville was the site of an asbestos products plant (1912 to 1980) that used primarily chrysotile asbestos (approximately 95%). The routes considered were ambient air and household contact with plant employees. Exposure was not measured for individuals.
• Main results:
  • Before plant workers were removed, Manville's average annual adjusted mesothelioma rate was 636 male and 96 female cases per million (Table 1: 635.6 and 95.9, ratios to state 25.8 and 23.2). New Jersey's rates were 25 male and 4 female cases per million.
  • Of 143 Somerset County cases, 61 were identified as having worked at the Manville plant: 55 by death certificates (90.2%), 41 by the union list (67.2%) and 30 by the Cancer Registry (49.2%), with sources overlapping. 82 cases had no evidence of plant employment.
  • Manville males not identified as plant workers had an SIR of 10.1 (95% CI: 5.8–16.4), based on 16 observed versus 1.6 expected cases.
  • Manville females not identified as plant workers had an SIR of 22.4 (95% CI: 9.7–44.2), based on 8 observed versus 0.4 expected cases.
  • In Somerset County excluding Manville, after removal of plant workers, the SIR was 1.9 (95% CI: 1.4–2.5) for males (47 observed versus 25.1 expected) and 2.0 (95% CI: 1.0–3.6) for females (11 observed versus 5.5 expected). Both were marked statistically elevated (p less than 0.05).
• The authors' conclusion: The author concluded that residents of Manville had an extremely elevated risk of developing mesothelioma relative to average state incidence rates. The author also stated that the study suggests a major community impact from a facility using primarily chrysotile fibers.
• Limitations the authors state:
  • Full occupational histories were not collected, so some included cases may have worked at the plant. The author states this would overestimate the environmental component.
  • The study could not distinguish cases due to ambient airborne contamination from cases due to household contact with an asbestos worker.
  • Plant employees could not be removed from the census population figures, which the author states would underestimate the effect, especially for Manville.
  • In-migration of unexposed people and out-migration of cases before diagnosis would bias the Manville SIRs toward the null.
  • Information on other risk factors, such as the extent of occupational exposure or personal lifestyle habits, was unknown for the study population.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Asbestos Exposure, Cancer Registry, Standardized Incidence Ratio (SIR), confidence interval, Incidence.

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