Children's exposure assessment of radiofrequency fields: Comparison between spot and personal measurements

Abstract

Children's exposure assessment of radiofrequency fields: Comparison between spot and personal measurements Gallastegi M, Huss A, Santa-Marina L, Aurrekoetxea JJ, Guxens M, Birks LE, Ibarluzea J, Guerra D, Röösli M. Children's exposure assessment of radiofrequency fields: Comparison between spot and personal measurements. Environment International. 118:60-69. Sep 2018. Highlights • Children's radiofrequency field levels and contribution of sources were assessed. • We contrasted exposure assessment based on spot and personal measurements. • Median exposures range: 29.73-236.31 μW/m2; broadcast and downlink contributed most. • Proportional bias between assessment based on spot and personal measurements. • No systematic differences when classifying subjects in exposure-dependent groups. Abstract Introduction Radiofrequency (RF) fields are widely used and, while it is still unknown whether children are more vulnerable to this type of exposure, it is essential to explore their level of exposure in order to conduct adequate epidemiological studies. Personal measurements provide individualized information, but they are costly in terms of time and resources, especially in large epidemiological studies. Other approaches, such as estimation of time- weighted averages (TWAs) based on spot measurements could simplify the work. Objectives The aims of this study were to assess RF exposure in the Spanish INMA birth cohort by spot measurements and by personal measurements in the settings where children tend to spend most of their time, i.e., homes, schools and parks; to identify the settings and sources that contribute most to that exposure; and to explore if exposure assessment based on spot measurements is a valid proxy for personal exposure. Methods When children were 8 years old, spot measurements were conducted in the principal settings of 104 participants: homes (104), schools and their playgrounds (26) and parks (79). At the same time, personal measurements were taken for a subsample of 50 children during 3 days. Exposure assessment based on personal and on spot measurements were compared both in terms of mean exposures and in exposure- dependent categories by means of Bland-Altman plots, Cohen's kappa and McNemar test. Results Median exposure levels ranged from 29.73 (in children's bedrooms) to 200.10 μW/m2 (in school playgrounds) for spot measurements and were higher outdoors than indoors. Median personal exposure was 52.13 μW/m2 and median levels of assessments based on spot measurements ranged from 25.46 to 123.21 μW/m2. Based on spot measurements, the sources that contributed most to the exposure were FM radio, mobile phone downlink and Digital Video Broadcasting-Terrestrial, while indoor and personal sources contributed very little (altogether <20%). Similar distribution was observed with personal measurements. There was a bias proportional to power density between personal measurements and estimates based on spot measurements, with the latter providing higher exposure estimates. Nevertheless, there were no systematic differences between those methodologies when classifying subjects into exposure categories. Personal measurements of total RF exposure showed low to moderate agreement with home and bedroom spot measurements and agreed better, though moderately, with TWA based on spot measurements in the main settings where children spend time (homes, schools and parks; Kappa = 0.46). Conclusions Exposure assessment based on spot measurements could be a feasible proxy to rank personal RF exposure in children population, providing that all relevant locations are being measured. sciencedirect.com

AI evidence extraction

Main findings

In 104 children (age 8), median spot-measured RF exposure ranged from 29.73 μW/m2 (bedrooms) to 200.10 μW/m2 (school playgrounds), with higher outdoor than indoor levels; median personal exposure (n=50) was 52.13 μW/m2. Broadcast (FM radio, DVB-T) and mobile phone downlink contributed most, while indoor/personal sources contributed <20%. Spot-based estimates showed proportional bias (tending to higher estimates than personal measurements), but no systematic differences in classifying children into exposure categories; agreement was low–moderate for home/bedroom spot measures and moderate for time-weighted averages across main settings (Kappa=0.46).

Outcomes measured

• RF power density exposure levels (μW/m2) in bedrooms, homes, schools/playgrounds, parks
• Source contributions to RF exposure (e.g., FM radio, mobile phone downlink, DVB-T)
• Agreement/bias between spot-based estimates and personal measurements (Bland-Altman, Cohen’s kappa, McNemar)
• Exposure-category classification agreement between methods

Limitations

• Personal measurements were conducted only in a subsample (50 children)
• Potential proportional bias between spot-based estimates and personal measurements (spot estimates higher)
• Validity of spot measurements as proxy depends on measuring all relevant locations (as noted by authors)

Suggested hubs

• school-wi-fi (0.22)
  Includes RF exposure measurements in schools and school playgrounds (though main sources reported are broadcast and downlink, not specifically Wi‑Fi).

{
    "study_type": "exposure_assessment",
    "exposure": {
        "band": "RF",
        "source": "environmental (homes, schools, parks); broadcast and mobile downlink",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "spot measurements in main settings; personal measurements for 3 days (subsample)"
    },
    "population": "Children (Spanish INMA birth cohort), age 8",
    "sample_size": 104,
    "outcomes": [
        "RF power density exposure levels (μW/m2) in bedrooms, homes, schools/playgrounds, parks",
        "Source contributions to RF exposure (e.g., FM radio, mobile phone downlink, DVB-T)",
        "Agreement/bias between spot-based estimates and personal measurements (Bland-Altman, Cohen’s kappa, McNemar)",
        "Exposure-category classification agreement between methods"
    ],
    "main_findings": "In 104 children (age 8), median spot-measured RF exposure ranged from 29.73 μW/m2 (bedrooms) to 200.10 μW/m2 (school playgrounds), with higher outdoor than indoor levels; median personal exposure (n=50) was 52.13 μW/m2. Broadcast (FM radio, DVB-T) and mobile phone downlink contributed most, while indoor/personal sources contributed <20%. Spot-based estimates showed proportional bias (tending to higher estimates than personal measurements), but no systematic differences in classifying children into exposure categories; agreement was low–moderate for home/bedroom spot measures and moderate for time-weighted averages across main settings (Kappa=0.46).",
    "effect_direction": "unclear",
    "limitations": [
        "Personal measurements were conducted only in a subsample (50 children)",
        "Potential proportional bias between spot-based estimates and personal measurements (spot estimates higher)",
        "Validity of spot measurements as proxy depends on measuring all relevant locations (as noted by authors)"
    ],
    "evidence_strength": "moderate",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "radiofrequency",
        "RF exposure",
        "children",
        "personal measurements",
        "spot measurements",
        "time-weighted average",
        "power density",
        "homes",
        "schools",
        "parks",
        "FM radio",
        "mobile downlink",
        "DVB-T",
        "INMA cohort"
    ],
    "suggested_hubs": [
        {
            "slug": "school-wi-fi",
            "weight": 0.2200000000000000011102230246251565404236316680908203125,
            "reason": "Includes RF exposure measurements in schools and school playgrounds (though main sources reported are broadcast and downlink, not specifically Wi‑Fi)."
        }
    ]
}

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