Static magnetic fields from earphones: Detailed measurements plus some open questions

Abstract

Static magnetic fields from earphones: Detailed measurements plus some open questions L. Makinistian, L. Zastko, A. Tvarožná, L.E. Días, I. Belyaev. Static magnetic fields from earphones: Detailed measurements plus some open questions. Environmental Research, 2022. doi: 10.1016/j.envres.2022.113907. Highlights • Experimental mapping of the static magnetic fields near 6 earphones. • Physical modeling of the measured fields allows extrapolation and simulation. • 3D simulations allow for visualization of field distribution in the ear. • Field intensity and gradients, plus their combination with RF/ELF should be studied. Abstract Earphones (EP) are a worldwide, massively adopted product, assumed to be innocuous provided the recommendations on sound doses limits are followed. Nevertheless, sound is not the only physical stimulus that derives from EP use, since they include a built-in permanent magnet from which a static magnetic field (SMF) originates. We performed 2D maps of the SMF at several distances from 6 models of in-ear EP, showing that they produce an exposure that spans from ca. 20 mT on their surface down to tens of μT in the inner ear. The numerous reports of bioeffects elicited by SMF in that range of intensities (applied both acutely and chronically), together with the fact that there is no scientific consensus over the possible mechanisms of interaction with living tissues, suggest that caution could be recommendable. In addition, more research is warranted on the possible effects of the combination of SMF with extremely low frequency and radiofrequency fields, which has so far been scarcely studied. Overall, while several open questions about bioeffects of SMF remain to be addressed by the scientific community, we find sensible to suggest that the use of air-tube earphones is probably the more conservative, cautious choice. Excerpt The International Commission on Non-Ionizing Radiation Protection recommends a 400 mT exposure limit for the general public (ICNIRP, 2009), which are way above the SMF reported here. It must be noted that the recommendation is based on the effects of nausea, vertigo, photo phosphenes and nerve stimulation, well associated to high and ultra-high magnetic fields (typical of MRI facilities). All the other reported biological effects, which are not directly proven to be a health hazard (but could be, such being the case of the increase of reactive oxygen species (Wang and Zhang, 2017)) are disregarded by the recommendation. sciencedirect.com

AI evidence extraction

Main findings

2D mapping of static magnetic fields around six in-ear earphone models found fields of about 20 mT at the earphone surface decreasing to tens of µT in the inner ear. The authors report that physical modeling and 3D simulations were used to extrapolate and visualize field distribution in the ear, and they note open questions about potential bioeffects and combined exposures with ELF/RF fields.

Outcomes measured

• Static magnetic field (SMF) intensity near in-ear earphones
• SMF spatial distribution (2D mapping) at several distances
• Estimated exposure levels in the inner ear (via modeling/simulation)

Limitations

• No health outcomes were measured; the work focuses on field measurements/modeling.
• Exposure duration and usage patterns are not described in the abstract.
• Only six in-ear earphone models were assessed.
• Statements about bioeffects and recommendations (e.g., air-tube earphones) are not supported by direct outcome data in the abstract.

Suggested hubs

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  Abstract excerpt discusses ICNIRP (2009) general public exposure limit for static magnetic fields.
• occupational-exposure (0.15)
  Mentions MRI-related high magnetic fields in context of guideline basis, but study itself is consumer earphones rather than occupational.

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