Effect of microwave radiation on the biophysical properties of liposomes.

Abstract

Steadily growing use of electromagnetic fields, especially in conjunction with wireless communication systems, has led to increasing public concern about possible health effects of electromagnetic radiation. However, besides the well-known thermal effect of electromagnetic fields on biological tissue, there is no clear evidence of further athermal interaction mechanisms with biological systems. The present study was designed to determine the changes in bilayer permeability in egg lecithin multilamellar vesicles after exposure to 900 MHz microwave radiation for a period of 5 h. Specific absorption rate (SAR) of the radiation for the investigated liposome sample was found to be 12 +/- 1 W/kg. Liposomal changes in permeability were monitored using a light scattering technique. Optical anisotropy of the liposome sample decreased dramatically upon exposure to microwave radiation, indicating structural changes in acyl chain packing. IR and NMR ((1)H NMR) studies, which have been employed to reveal structural alterations in microwave, exposed vesicles showed an increased damage upon exposure to microwave. The changes observed in the (1)H NMR spectrum of the microwave exposed sample indicated hydrolysis of carboxylic and phosphoric esters. IR study showed conformational changes in the acyl chains of the lipids upon microwave exposure. However, both IR and (31)P NMR did not show any appreciable changes in the head group part of the lipids.

AI evidence extraction

Main findings

Egg lecithin multilamellar vesicles exposed to 900 MHz microwave radiation (SAR 12 ± 1 W/kg) for 5 h showed a dramatic decrease in optical anisotropy, interpreted as structural changes in acyl chain packing. IR and 1H NMR measurements indicated increased damage after exposure, including spectral changes consistent with hydrolysis of carboxylic and phosphoric esters and conformational changes in acyl chains, while IR and 31P NMR did not show appreciable changes in lipid head groups.

Outcomes measured

• bilayer permeability
• optical anisotropy (light scattering)
• acyl chain packing/structural changes
• IR spectroscopy changes
• 1H NMR changes (hydrolysis of esters)
• 31P NMR changes (head group)

Limitations

• In vitro liposome model; findings may not translate to intact biological tissues or health outcomes
• No sample size reported in abstract
• Thermal vs athermal contribution not resolved in abstract (SAR is high and heating is not described)
• Exposure conditions limited to a single frequency (900 MHz) and duration (5 h)

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "RF",
        "source": null,
        "frequency_mhz": 900,
        "sar_wkg": 12,
        "duration": "5 h"
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "bilayer permeability",
        "optical anisotropy (light scattering)",
        "acyl chain packing/structural changes",
        "IR spectroscopy changes",
        "1H NMR changes (hydrolysis of esters)",
        "31P NMR changes (head group)"
    ],
    "main_findings": "Egg lecithin multilamellar vesicles exposed to 900 MHz microwave radiation (SAR 12 ± 1 W/kg) for 5 h showed a dramatic decrease in optical anisotropy, interpreted as structural changes in acyl chain packing. IR and 1H NMR measurements indicated increased damage after exposure, including spectral changes consistent with hydrolysis of carboxylic and phosphoric esters and conformational changes in acyl chains, while IR and 31P NMR did not show appreciable changes in lipid head groups.",
    "effect_direction": "harm",
    "limitations": [
        "In vitro liposome model; findings may not translate to intact biological tissues or health outcomes",
        "No sample size reported in abstract",
        "Thermal vs athermal contribution not resolved in abstract (SAR is high and heating is not described)",
        "Exposure conditions limited to a single frequency (900 MHz) and duration (5 h)"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "microwave radiation",
        "900 MHz",
        "RF",
        "liposomes",
        "egg lecithin",
        "multilamellar vesicles",
        "SAR",
        "permeability",
        "light scattering",
        "optical anisotropy",
        "IR spectroscopy",
        "NMR",
        "1H NMR",
        "31P NMR",
        "acyl chain packing",
        "hydrolysis"
    ],
    "suggested_hubs": []
}

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