Intraocular melanoma linked to occupations and chemical exposures

Our plain-English summary of Intraocular melanoma linked to occupations and chemical exposures, by E.A. Holly, D.A. Aston, D.K. Ahn, et al (Epidemiology, 1996).

The study

• Authors: E.A. Holly, D.A. Aston, D.K. Ahn, A.H. Smith
• Journal: Epidemiology
• Published: 1996;7(1):55-61
• Cited by: 69 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We conducted a case-control study in the western United States to determine the relation between occupations or chemical exposures and increased risk of uveal melanoma. Among men (221 patients, 447 controls), we found increased risks for occupational groups who had intense exposure to ultraviolet light [odds ratio (OR) = 3.0; 95% confidence interval (CI) = 1.2-7.8], welding exposure (OR = 2.2; 95% CI = 1.3-3.5), and asbestos exposure (OR = 2.4; 95% CI = 1.5-3.9 for most likely exposed). The highest odds ratio was for the small number of men (nine cases, three controls) who were chemists, chemical engineers, and chemical technicians (OR = 5.9; 95% CI = 1.6-22.7). Odds ratios also were elevated for exposures to antifreeze, formaldehyde, pesticides, and carbon tetrachloride, but these findings, based on recall of specific chemical exposures, are more subject to recall bias than the findings based on occupational groups.

In plain English

This case-control study asked whether jobs or chemical exposures were linked to uveal melanoma, an eye cancer, in white men in the western United States. The authors compared 221 men diagnosed at, or referred to, a University of California San Francisco eye cancer unit in 1978 to 1987 with 447 men found by random telephone dialing. One author graded each man's likely asbestos exposure from job and industry descriptions, without knowing who was a patient. Men in the highest grade, labeled in the table as "moderately or highly likely, and yes" (43 patients, 43 controls), had an odds ratio of 2.4 (95% CI 1.5 to 3.9), and risk rose across grades. Raised odds ratios were also found for welding exposure (2.2; 95% CI 1.3 to 3.5), sailors, ship officers or fishermen (3.0; 1.2 to 7.8), and chemists, chemical engineers and chemical technicians (5.9; 1.6 to 22.7; nine patients, three controls). The authors cautioned that findings based on recalled chemical exposures are more open to recall bias, and that some groups were small. No asbestos fiber type was named.

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 (patients compared with population controls chosen by random digit dialing; telephone questionnaire; unconditional logistic regression)
• Who was studied: 221 white men aged 20 to 74 with uveal melanoma, diagnosed at or referred to the Ocular Oncology Unit at the University of California San Francisco between January 1978 and February 1987, living in 11 western US states (93% of eligible patients took part). They were compared with 447 white male controls from the same geographic area and 5-year age group, found by random digit dialing (77% of eligible controls were interviewed).
• Exposure: Occupations (the six jobs held longest) and self-reported chemical exposures (at least 3 hours per week for at least 6 months), including antifreeze, formaldehyde, pesticides, carbon tetrachloride and other cleaning fluids, radar or microwaves, and asbestos. Welding exposure was also studied. Asbestos was assessed two ways: by questionnaire answer, and by one author's expert grading (unlikely, somewhat likely, or moderately or highly likely) based on job and industry descriptions, done without knowing case or control status. No asbestos fiber type is specified.
• Main results:
  • Asbestos, expert-graded: men in the highest grade, which the table labels "Moderately or highly likely, and yes" (43 patients, 19%; 43 controls, 10%), had an odds ratio of 2.4 (95% CI 1.5 to 3.9) compared with men graded unlikely to have been exposed.
  • The graded asbestos exposure showed a trend of increasing risk from no exposure to moderately or highly likely exposure (P for trend = 0.01).
  • Asbestos, by questionnaire answer: 31 patients (14%) and 36 controls (8%) reported ever being exposed. The table shows odds ratios of 1.9 and 1.8, both with a lower confidence limit of 1.1. The scanned table does not make clear which figure is unadjusted and which is adjusted.
  • Welding exposure (40 patients, 18%; 47 controls, 11%): odds ratio 2.2 (95% CI 1.3 to 3.5).
  • Sailors, ship officers, or fishermen, grouped as occupations with intense ultraviolet light exposure (12 patients, 8 controls): odds ratio 3.0 (95% CI 1.2 to 7.8).
  • Chemists, chemical engineers, and chemical technicians (9 patients, 3 controls) had the highest odds ratio: 5.9 (95% CI 1.6 to 22.7).
  • Odds ratios were also raised for reported exposure to antifreeze, formaldehyde, pesticides, and carbon tetrachloride, but these findings rest on recall of specific chemicals.
• The authors' conclusion: The authors concluded that they found an increased risk of uveal melanoma for four occupational groups, some related to chemical exposures and others to ultraviolet light, and that intense ultraviolet light exposure to the eye is associated with increased risk. They suspected that the raised risk for health-related occupations may reflect referral bias.
• Limitations the authors state:
  • Findings for specific chemical exposures are based on recall and are more subject to recall bias than the findings based on occupational groups.
  • Numbers of subjects in the duration-of-exposure categories were quite small.
  • The raised odds ratio for health-related occupations may have resulted from referral bias, since these patients had better access to specialists.
  • The men were not asked whether they wore protective face masks when welding.
  • Short, intense exposures in work periods of under 6 months may have been missed.

Topics

Medical terms in this study, explained in our Lexicon: Case-Control Study, Odds Ratio, confidence interval, Asbestos Exposure, Recall Bias.

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