Effects of microwave radiation on anti-infective factors in human milk.

PAPER pubmed Pediatrics 1992 Other Effect: mixed Evidence: Low

Read original paper → PMID: 1557249 Evidence Lab

Abstract

In intensive care nurseries it has become common practice to use microwave thawing of frozen human milk for more rapid accessibility. Twenty-two freshly frozen human milk samples were tested for lysozyme activity, total IgA, and specific secretory IgA to Escherichia coli serotypes 01, 04, and 06. The samples were heated by microwave for 30 seconds at a low- or high-power setting and then reanalyzed. One-mL aliquots of 10 additional human milk samples were microwaved at low (20 degrees C to 25 degrees C), medium (60 degrees C to 70 degrees C), and high (greater than or equal to 98 degrees C) setting before the addition to each of 1 mL of diluted E coli suspension. E coli growth was determined after 3 1/2 hours of incubation at 37 degrees C. Microwaving at high temperatures (72 degrees C to 98 degrees C) caused a marked decrease in activity of all the tested antiinfective factors. E coli growth at greater than or equal to 98 degrees C was 18 times that of control human milk. Microwaving at low temperatures (20 degrees C to 53 degrees C) had no significant effect on total IgA, specific IgA to E coli serotypes 01 and 04, but did significantly decrease lysozyme and specific IgA to E coli serotype 06. Even at 20 degrees C to 25 degrees C, E coli growth was five times that of control human milk. Microwaving appears to be contraindicated at high temperatures, and questions regarding its safety exist even at low temperatures.

AI evidence extraction

At a glance

Study type

Other

Effect direction

mixed

Population

Human milk samples (freshly frozen)

Sample size

Exposure

microwave microwave thawing/heating of human milk · 30 seconds (low- or high-power setting); additional aliquots microwaved at low/medium/high temperature settings

Evidence strength

Low

Confidence: 78% · Peer-reviewed: yes

Main findings

High-temperature microwaving (reported 72°C to 98°C) caused a marked decrease in activity of all tested anti-infective factors, and E. coli growth at ≥98°C was 18 times that of control human milk. Low-temperature microwaving (20°C to 53°C) showed no significant effect on total IgA or specific IgA to E. coli O1 and O4, but significantly decreased lysozyme and specific IgA to E. coli O6; even at 20°C to 25°C, E. coli growth was five times that of control human milk.

Outcomes measured

Lysozyme activity
Total IgA
Specific secretory IgA to Escherichia coli serotypes O1, O4, O6
E. coli growth after incubation

Limitations

Frequency and exposure metrics (e.g., microwave frequency, SAR) not reported in abstract
Sample-based laboratory study; no clinical outcomes reported
Small sample sizes (22 samples for immune factors; 10 samples for bacterial growth assay)
Temperature ranges/settings described, but detailed heating uniformity or exact protocols not provided in abstract

Suggested hubs

other (0.2)
Microwave heating of human milk; not clearly tied to telecom RF/ELF exposure hubs.

View raw extracted JSON

{
    "study_type": "other",
    "exposure": {
        "band": "microwave",
        "source": "microwave thawing/heating of human milk",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "30 seconds (low- or high-power setting); additional aliquots microwaved at low/medium/high temperature settings"
    },
    "population": "Human milk samples (freshly frozen)",
    "sample_size": 32,
    "outcomes": [
        "Lysozyme activity",
        "Total IgA",
        "Specific secretory IgA to Escherichia coli serotypes O1, O4, O6",
        "E. coli growth after incubation"
    ],
    "main_findings": "High-temperature microwaving (reported 72°C to 98°C) caused a marked decrease in activity of all tested anti-infective factors, and E. coli growth at ≥98°C was 18 times that of control human milk. Low-temperature microwaving (20°C to 53°C) showed no significant effect on total IgA or specific IgA to E. coli O1 and O4, but significantly decreased lysozyme and specific IgA to E. coli O6; even at 20°C to 25°C, E. coli growth was five times that of control human milk.",
    "effect_direction": "mixed",
    "limitations": [
        "Frequency and exposure metrics (e.g., microwave frequency, SAR) not reported in abstract",
        "Sample-based laboratory study; no clinical outcomes reported",
        "Small sample sizes (22 samples for immune factors; 10 samples for bacterial growth assay)",
        "Temperature ranges/settings described, but detailed heating uniformity or exact protocols not provided in abstract"
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "microwave radiation",
        "human milk",
        "microwave thawing",
        "lysozyme",
        "IgA",
        "secretory IgA",
        "Escherichia coli",
        "anti-infective factors",
        "neonatal intensive care"
    ],
    "suggested_hubs": [
        {
            "slug": "other",
            "weight": 0.200000000000000011102230246251565404236316680908203125,
            "reason": "Microwave heating of human milk; not clearly tied to telecom RF/ELF exposure hubs."
        }
    ]
}

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

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