Stereological analysis of thyroid mast cells in rats after exposure to extremely low frequency electromagnetic field and the following "off" field period.

Abstract

Influence of extremely low frequency electromagnetic field (ELF-EMF) on thyroid gland mast cells was investigated on male Mill Hill rats. Animals were exposed to EMF (50 Hz, 50 microT to 500 microT, 10 V/m) from 24 hours after birth, 7 hours/day, 5 days/week for three months when a part of animals (group I) was sacrificed, while the rest of them were subjected to recovery evaluation and sacrificed after one (group II), two (group II) and three (group IV) weeks following the exposure. Stereological analysis on toluidine blue-stained paraffin sections showed increased volume density of degranulated mast cells in all groups and, except in group III, and numerical density as well, implicating the sensitivity of thyroidal mast cells to power frequency EMFs. Since in our previous investigations, morphofunctional alterations of thyroid gland in rats exposed to ELF-EMF were found the contribution of released mast cell mediators to these changes could be presumed.

AI evidence extraction

Main findings

Stereological analysis of thyroid sections showed increased volume density of degranulated mast cells in all groups after ELF-EMF exposure and during the off-field period. Numerical density was also increased in all groups except group III.

Outcomes measured

• Thyroid gland mast cells (degranulated mast cells volume density)
• Thyroid gland mast cells (numerical density)

Limitations

• Sample size not reported in abstract
• No quantitative effect sizes or statistical details reported in abstract
• Animal model; relevance to humans not established in abstract

Suggested hubs

• occupational-exposure (0.25)
  Power-frequency (50 Hz) ELF exposure parameters may be relevant to occupational/environmental ELF discussions, though this is an animal study.

{
    "study_type": "animal",
    "exposure": {
        "band": "ELF",
        "source": "other",
        "frequency_mhz": 0.05000000000000000277555756156289135105907917022705078125,
        "sar_wkg": null,
        "duration": "From 24 hours after birth; 7 hours/day, 5 days/week for 3 months; followed by 1–3 weeks off-field period"
    },
    "population": "Male Mill Hill rats",
    "sample_size": null,
    "outcomes": [
        "Thyroid gland mast cells (degranulated mast cells volume density)",
        "Thyroid gland mast cells (numerical density)"
    ],
    "main_findings": "Stereological analysis of thyroid sections showed increased volume density of degranulated mast cells in all groups after ELF-EMF exposure and during the off-field period. Numerical density was also increased in all groups except group III.",
    "effect_direction": "harm",
    "limitations": [
        "Sample size not reported in abstract",
        "No quantitative effect sizes or statistical details reported in abstract",
        "Animal model; relevance to humans not established in abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "ELF-EMF",
        "50 Hz",
        "microtesla",
        "thyroid",
        "mast cells",
        "degranulation",
        "stereology",
        "rats",
        "off-field period",
        "power frequency"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.25,
            "reason": "Power-frequency (50 Hz) ELF exposure parameters may be relevant to occupational/environmental ELF discussions, though this is an animal study."
        }
    ]
}

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