Exposure to 50-Hz electric field and incidence of leukemia, brain tumors, and other cancers among French electric utility workers.

American journal of epidemiology · 1996 · Mixed · Low evidence

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MixedLow evidencePaper 4180

Study snapshot

PublicationAmerican journal of epidemiology · 1996

Study typecase_control

Reported directionMixed

Evidence ratingLow

Abstract

Recent studies on the association between exposure to 50- to 60-Hz fields and cancer carried out among electric utility workers have focused mainly on the magnetic field component of exposure. The authors have investigated tumor risks specifically associated with electric fields, as this exposure is distinct from magnetic fields. The study design is a case-control study nested within a cohort of 170,000 workers employed at Electricité de France-Gaz de France (EDF) between 1978 and 1989. All incident cases of cancer and benign tumor of the brain diagnosed in 1978-1989 among workers before the age of retirement were included. Four randomly selected controls were individually matched to each case by year of birth. The exposure to electric fields was assessed from measurements collected in 850 EDF workers for a full work week. Arithmetic and geometric mean exposures were included in a job-exposure matrix to determine the cumulative exposure of the cases and the controls. Exposures to potentially carcinogenic chemicals found at the workplace were also evaluated through expert judgment. The analysis by site of tumor did not show any increased risk for leukemia (72 cases). An odds ratio of 3.08 (95% confidence interval 1.08-8.74) was observed for all brain tumors (69 cases) for exposure above the 90th percentile (> or = 387 V/m-year), and there was some indication of a dose-response relation, although the risk did not increase monotonically with exposure. No confounding from magnetic fields or from other potentially carcinogenic hazards was apparent. The observed association was somewhat stronger after allowing a 5-year latency period before diagnosis (odds ratio = 3.69, 95% confidence interval 1.10-12.43) for exposure above the 90th percentile. However, the risk of brain tumor could not be linked to a specific type of tumor. An unexpected association was also observed for colon cancer, using geometric indexes of exposure, but no other association was seen for any other type of cancer. Our study indicates that electric fields may have a specific effect on the risk of brain tumor, and that this should be taken into account in future analyses on the carcinogenic effects of 50- to 60-Hz fields.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typecase_control

Effect directionmixed

PopulationFrench electric utility workers (Electricité de France-Gaz de France, EDF) employed 1978–1989, before retirement age

Sample size170000

ExposureELF · Cumulative exposure estimated for 1978–1989; measurements collected for a full work week in 850 workers

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

In this nested case-control study within a cohort of 170,000 EDF workers (1978–1989), no increased risk was found for leukemia (72 cases). For all brain tumors (69 cases), exposure above the 90th percentile (≥387 V/m-year) was associated with increased risk (OR 3.08, 95% CI 1.08–8.74), with some indication of dose-response but not monotonic. The association was somewhat stronger with a 5-year latency (OR 3.69, 95% CI 1.10–12.43); no apparent confounding from magnetic fields or other workplace carcinogenic hazards was observed; an unexpected association was also reported for colon cancer using geometric exposure indexes.

Outcomes measured

Leukemia incidence
Brain tumors (all) incidence
Benign tumor of the brain incidence
Colon cancer incidence
Other cancers incidence

Limitations

Risk for brain tumor did not increase monotonically with exposure.
Brain tumor risk could not be linked to a specific tumor type.
Colon cancer association described as unexpected (suggesting potential chance finding).

View raw extracted JSON

{
  "study_type": "case_control",
  "exposure": {
    "band": "ELF",
    "source": "occupational",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "Cumulative exposure estimated for 1978–1989; measurements collected for a full work week in 850 workers"
  },
  "population": "French electric utility workers (Electricité de France-Gaz de France, EDF) employed 1978–1989, before retirement age",
  "sample_size": 170000,
  "outcomes": [
    "Leukemia incidence",
    "Brain tumors (all) incidence",
    "Benign tumor of the brain incidence",
    "Colon cancer incidence",
    "Other cancers incidence"
  ],
  "main_findings": "In this nested case-control study within a cohort of 170,000 EDF workers (1978–1989), no increased risk was found for leukemia (72 cases). For all brain tumors (69 cases), exposure above the 90th percentile (≥387 V/m-year) was associated with increased risk (OR 3.08, 95% CI 1.08–8.74), with some indication of dose-response but not monotonic. The association was somewhat stronger with a 5-year latency (OR 3.69, 95% CI 1.10–12.43); no apparent confounding from magnetic fields or other workplace carcinogenic hazards was observed; an unexpected association was also reported for colon cancer using geometric exposure indexes.",
  "effect_direction": "mixed",
  "limitations": [
    "Risk for brain tumor did not increase monotonically with exposure.",
    "Brain tumor risk could not be linked to a specific tumor type.",
    "Colon cancer association described as unexpected (suggesting potential chance finding)."
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "50-Hz",
    "ELF electric fields",
    "occupational exposure",
    "electric utility workers",
    "job-exposure matrix",
    "nested case-control",
    "brain tumors",
    "leukemia",
    "colon cancer"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.9,
      "reason": "Study population is electric utility workers with workplace ELF electric-field exposure assessment."
    }
  ]
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1093/oxfordjournals.aje.a008889
PubMed: 8956623

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