Extremely low frequency-magnetic fields (ELF-EMF) occupational exposure and natural killer activity in peripheral blood lymphocytes.

The Science of the total environment · 2009 · Harm · Low evidence

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HarmLow evidencePaper 4980

Study snapshot

PublicationThe Science of the total environment · 2009

Study typecohort

Reported directionHarm

Evidence ratingLow

Abstract

Extremely Low Frequency-Magnetic Fields (ELF-MF) are possible carcinogens to humans and some data suggest that they can act as promoters or progressors. Since NK cells play a major role in the control of cancer development, an adverse effect on ELF-MF on NK function has been hypothesized. We examined NK activity in 52 workers exposed to different levels of ELF-MF in various activities. Individual exposure was monitored during 3 complete work-shifts using personal dosimeters. Environmental exposure was also monitored. ELF-MF levels in the workers were expressed as Time-Weighted Average (TWA) values. NK activity was measured in peripheral blood lymphocytes (PBL). In the whole group the median occupational TWA was 0.21 microT. According to the TWA levels, workers were classified as low exposed (26 subjects, TWA < or =0.2 microT) and higher exposed workers (26 subjects; TWA >0.2 microT). In higher exposed workers, we observed a trend to reduce NK activity compared to low exposed, but the difference was not significant. Then we selected a subgroup of highest exposed workers (12 subjects; TWA >1 microT); no difference was observed between low and highest exposed subjects in the main personal variables. Considering both E:T ratios from 12:1 to 50:1 and Lytic Units, a significant reduction in NK activity was observed in the highest exposed workers compared to the low exposed. Multivariate analysis showed a significant negative correlation between exposure and LU, while no correlation was evidenced with other personal characteristics. ELF-MF are considered possible carcinogens, and existing data suggest that they can act as promoters. Due to the role of NK activity in host defence against cancer, the results obtained in this study in workers exposed to ELF-MF levels exceeding 1 microT are in agreement with this hypothesis, and support the need for further investigation in this field.

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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 typecohort

Effect directionharm

PopulationWorkers exposed to different levels of ELF-MF in various activities

Sample size52

ExposureELF · 3 complete work-shifts (personal dosimetry monitoring)

Evidence strengthLowConfidence: 78% · Peer reviewed: yes

Main findings

Among 52 workers, those with higher exposure (TWA >0.2 microT) showed a non-significant trend toward reduced NK activity versus low exposure (TWA ≤0.2 microT). In a subgroup of highest exposed workers (TWA >1 microT; n=12), NK activity was significantly reduced compared with low exposed workers across E:T ratios and in Lytic Units; multivariate analysis found a significant negative correlation between exposure and LU.

Outcomes measured

Natural killer (NK) cell activity in peripheral blood lymphocytes (PBL)
Lytic Units (LU)
NK activity at different effector:target (E:T) ratios (12:1 to 50:1)

Limitations

Observational design (workers grouped by exposure; no randomization)
Small highest-exposure subgroup (n=12)
Exposure monitoring limited to 3 work-shifts
Difference between low and higher exposure group (TWA >0.2 microT) was not statistically significant

View raw extracted JSON

{
  "study_type": "cohort",
  "exposure": {
    "band": "ELF",
    "source": "occupational",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": "3 complete work-shifts (personal dosimetry monitoring)"
  },
  "population": "Workers exposed to different levels of ELF-MF in various activities",
  "sample_size": 52,
  "outcomes": [
    "Natural killer (NK) cell activity in peripheral blood lymphocytes (PBL)",
    "Lytic Units (LU)",
    "NK activity at different effector:target (E:T) ratios (12:1 to 50:1)"
  ],
  "main_findings": "Among 52 workers, those with higher exposure (TWA >0.2 microT) showed a non-significant trend toward reduced NK activity versus low exposure (TWA ≤0.2 microT). In a subgroup of highest exposed workers (TWA >1 microT; n=12), NK activity was significantly reduced compared with low exposed workers across E:T ratios and in Lytic Units; multivariate analysis found a significant negative correlation between exposure and LU.",
  "effect_direction": "harm",
  "limitations": [
    "Observational design (workers grouped by exposure; no randomization)",
    "Small highest-exposure subgroup (n=12)",
    "Exposure monitoring limited to 3 work-shifts",
    "Difference between low and higher exposure group (TWA >0.2 microT) was not statistically significant"
  ],
  "evidence_strength": "low",
  "confidence": 0.78,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "ELF-MF",
    "ELF-EMF",
    "occupational exposure",
    "personal dosimetry",
    "time-weighted average",
    "microtesla",
    "natural killer cells",
    "NK activity",
    "peripheral blood lymphocytes",
    "lytic units"
  ],
  "suggested_hubs": [
    {
      "slug": "occupational-exposure",
      "weight": 0.9,
      "reason": "Study evaluates ELF magnetic-field exposure in workers using personal dosimeters and relates exposure to immune function outcomes."
    }
  ]
}

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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: 10.1016/j.scitotenv.2008.08.012
PubMed: 18804846

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