Follow-up of radio and telegraph operators with exposure to electromagnetic fields and risk of breast cancer.

Abstract

It is still unclear whether exposure to electromagnetic fields (EMF) is associated with breast cancer. To further investigate the issue, we followed-up a cohort of Norwegian female radio and telegraph operators in the period 1 January 1961 to 31 May 2002, with 99 breast cancer cases. The standardized incidence ratio (SIR) for breast cancer was 1.30 (95% confidence intervals (CI) 1.05-1.58), compared with the total Norwegian female population. In a subsequent nested case-control study, exposure to radio frequency (405 kHz-25 MHz) and extremely low-frequency (50 Hz) fields due to stay in the radio room during day and night was cumulated by years of employment and workload according to ship type. The exposure was assessed in two age groups (<50, 50+) with regard to risk of breast cancer. The odds ratios in the group with the highest cumulative exposure were 1.78 (95% CI 0.59-5.41) and 2.37 (95% CI 0.88-6.36) in the younger and the older women, respectively. P-value for trend was 0.03 in both age groups. The results of the oestrogen receptor status analysis by exposure to EMF showed an increased risk of oestrogen receptor-positive breast cancer in the younger women, while the older age group had an elevated risk of oestrogen receptor-negative breast cancer. Thus, the present study contributes to the hypothesis of an association between occupational exposure to EMF and increased risk of breast cancer.

AI evidence extraction

Main findings

In a cohort follow-up (1961–2002) with 99 breast cancer cases, breast cancer incidence was elevated versus the total Norwegian female population (SIR 1.30, 95% CI 1.05–1.58). In a nested case-control analysis, the highest cumulative exposure group had ORs of 1.78 (95% CI 0.59–5.41) for women <50 and 2.37 (95% CI 0.88–6.36) for women 50+, with trend p=0.03 in both age groups. ER-status analyses suggested increased risk of ER-positive breast cancer in younger women and elevated risk of ER-negative breast cancer in older women.

Outcomes measured

• Breast cancer incidence
• Breast cancer risk by cumulative RF (405 kHz–25 MHz) and ELF (50 Hz) exposure
• Oestrogen receptor (ER) status-specific breast cancer risk

Limitations

• Sample size not reported in abstract (beyond 99 cases)
• Exposure assessment based on time in radio room and cumulative years/workload by ship type (potential exposure misclassification)
• Wide confidence intervals for odds ratios in highest exposure categories

Suggested hubs

• occupational-exposure (0.95)
  Study of occupational EMF exposure among radio and telegraph operators and breast cancer risk.

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    "study_type": "cohort",
    "exposure": {
        "band": "ELF/RF",
        "source": "occupational",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "Follow-up 1 January 1961 to 31 May 2002; exposure cumulated by years of employment and workload (nested case-control)"
    },
    "population": "Norwegian female radio and telegraph operators",
    "sample_size": null,
    "outcomes": [
        "Breast cancer incidence",
        "Breast cancer risk by cumulative RF (405 kHz–25 MHz) and ELF (50 Hz) exposure",
        "Oestrogen receptor (ER) status-specific breast cancer risk"
    ],
    "main_findings": "In a cohort follow-up (1961–2002) with 99 breast cancer cases, breast cancer incidence was elevated versus the total Norwegian female population (SIR 1.30, 95% CI 1.05–1.58). In a nested case-control analysis, the highest cumulative exposure group had ORs of 1.78 (95% CI 0.59–5.41) for women <50 and 2.37 (95% CI 0.88–6.36) for women 50+, with trend p=0.03 in both age groups. ER-status analyses suggested increased risk of ER-positive breast cancer in younger women and elevated risk of ER-negative breast cancer in older women.",
    "effect_direction": "harm",
    "limitations": [
        "Sample size not reported in abstract (beyond 99 cases)",
        "Exposure assessment based on time in radio room and cumulative years/workload by ship type (potential exposure misclassification)",
        "Wide confidence intervals for odds ratios in highest exposure categories"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "breast cancer",
        "occupational exposure",
        "radio operators",
        "telegraph operators",
        "radio frequency",
        "extremely low frequency",
        "50 Hz",
        "405 kHz-25 MHz",
        "standardized incidence ratio",
        "nested case-control",
        "oestrogen receptor status"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.9499999999999999555910790149937383830547332763671875,
            "reason": "Study of occupational EMF exposure among radio and telegraph operators and breast cancer risk."
        }
    ]
}

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