Study type: Medical/biological study (observational study)

Biomonitoring of estrogen and melatonin metabolites among women residing near radio and television broadcasting transmitters med./bio.

By: Clark ML, Burch JB, Yost MG, Zhai Y, Bachand AM, Fitzpatrick CT, Ramaprasad J, Cragin LA, Reif JS
Published in: J Occup Environ Med 2007; 49 (10): 1149-1156
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Aim of study (acc. to author)

To test the hypothesis that radiofrequency or 60 Hz exposures reduce melatonin and increase estrogen production, the authors measured a urinary metabolite of each hormone among women living in a community with increased radiofrequency power densities from nearby radio and TV broadcasting antennae.

Background/further details

A total of 127 women aged 12 to 81 years participated. Each woman was studied for a 2.5-day period beginning in the evening on the initial day and ending in the morning on the final day. Each subject collected one overnight urine sample immediately after their first night of participation and a second overnight sample on their final participation night.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 0.1–3,000 MHz
Exposure 2: 60 Hz

General information

The study area, participant population, and RF exposure characteristics have been described in [Burch et al., 2006]. Exposure assessment included RF spot measurements inside and outside the home, and continuous personal monitoring for 60-Hz magnetic field and ambient light exposures. Participants were recruited from 161 residences with high (>4.0 µW/cm²), medium (0.5 to 4.0 µW/cm²), or low (<0.5 µW/cm²) RF exposures.

Exposure 1

Main characteristics
Frequency 0.1–3,000 MHz
Type
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
power density 0.04 µW/cm² mean measured - quartile 1
power density 0.2 µW/cm² mean measured - quartile 2
power density 0.4 µW/cm² mean measured - quartile 3
power density 1.4 µW/cm² mean measured - quartile 4
Measurement and calculation details

The average distance from each residence to 15 major transmitters in the study area, the home elevation, and the percentage of transmitters visible from each home were used for RF exposure assessment along with the house average power density. RF power densities were obtained from one exterior and five averaged interior locations using a survey meter with an isotropic E-field probe (flat response: 0.1 to 3000 MHz, detection limit: 0.2 V/m). Non-detectable measurements were assigned a value of one-half the detection limit (0.01 µW/cm²).

Exposure 2

Main characteristics
Frequency 60 Hz
Type
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 20 nT mean measured - quartile 1
magnetic flux density 30 nT mean measured - quartile 2
magnetic flux density 50 nT mean measured - quartile 3
magnetic flux density 130 nT mean measured - quartile 4
Measurement and calculation details

Personal exposure to 60-Hz magnetic fields and ambient light was logged continuously at 15-s intervals using EMDEX II meters adapted with a light sensor [Burch et al., 1998] worn at the waist during the day and placed bedside the waist during sleep. Time-weighted average MF exposure intensity (geometric mean) and temporal stability (standardized rate of change metric, RCMS) were calculated for the periods from sunset until bedtime and from sunrise until 4 hours later [Burch et al., 1998, 1999, and 2000].

Reference articles

  • Burch JB et al. (2006): Radio frequency nonionizing radiation in a community exposed to radio and television broadcasting
  • Burch JB et al. (2000): Melatonin metabolite levels in workers exposed to 60-Hz magnetic fields: work in substations and with 3-phase conductors
  • Burch JB et al. (1999): Reduced excretion of a melatonin metabolite in workers exposed to 60 Hz magnetic fields
  • Burch JB et al. (1998): Nocturnal excretion of a urinary melatonin metabolite among electric utility workers

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

An association between radiofrequency and 60 Hz exposures and increased estrone-3-glucuronide excretion was observed among postmenopausal but not premenopausal women. This association was strongest among postmenopausal women with low 6-hydroxymelatoninsulfate levels. Women with reduced nocturnal 6-hydroxymelatoninsulfate excretion may represent a sensitive subgroup.

Study character:

Study funded by

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