EXPERT REACTION: Do mobile phones on Wi-Fi impact sperm?

The conference abstract that Chou and colleagues have presented does not provide evidence for their claim that Wi-Fi is harmful in terms of sperm function.

It is difficult to know whether the lack of evidence is simply due to the premature nature of the report (it is being presented in a form that is too brief to allow evaluation, and that has not yet undergone peer review), or whether it is due to limitations within the study itself.

Perhaps further detail will emerge during the development of the report and subsequent peer-review process, but at present a number of key questions raise serious doubts regarding the veracity of the authors’ claims:

1. There is insufficient statistical detail to determine whether the results are more than mere chance;

2. There is no indication that the samples were in fact exposed to higher radiofrequency electromagnetic emissions (RF EMFs) during the Wi-Fi than control conditions;

3. There is no indication of which conditions were being compared to which, which is particularly important for interpretation;

4. There does not appear to be any experimental manipulation that would enable the authors to differentiate between a heating effect (e.g. from the battery) and an effect due directly to the RF EMF, which makes the authors’ conclusion that there was an effect that was due to a combination of heating and RF EMF unsupported;

5. There are important inconsistencies in their results, such as the authors’ claim that RF EMF had an effect, whereas it was only the condition with the lowest RF EMF (Wi-Fi) that they claim had an effect;

6. There is no demonstration that the reported effect (if real) would be harmful, rather than merely a normal heat-related biological change (e.g. due to the phone’s battery rather than a Wi-Fi signal).

The RF EMF due to Wi-Fi is extremely small relative to not only talking on your phone, but also to traditional AM and RM radio emissions (circa 1,000 to 10,000 times smaller than the safe levels specified in the ICNIRP 2020 RF EMF guidelines).

At present, there is no substantiated evidence in the scientific literature showing that such low levels of RF EMF can have any adverse effects on people, including sperm function. We will of course need to wait for Chou and colleagues’ full study to be published to determine what can be concluded from it, but there is no indication that RF EMF from Wi-Fi is harmful from what they have presented so far.

A number of previous studies have investigated exposure to radiofrequency (RF) electromagnetic fields and the effects on male fertility. A particular topic of interest is males keeping a mobile phone in their pocket and the possible effects on sperm quality. There have been a number of in vitro experiments investigating oxidative stress as a possible link between RF exposure and adverse bio-effects. To date, the link between the low RF exposure produced by mobile phones and effects on sperm quality remains tenuous with most of the studies having a number of methodological limitations.

 
Based on the conference abstract of the study by Chu et al, the authors do not seem to have improved on the methodological limitations of previous studies, and in fact, their methodology seems to be somewhat worse in terms of the dosimetry employed in the study. The RF exposure does not seem to be well controlled as the study seems to employ various wireless devices as the sources of exposure. There seems to be no dosimetric assessment in terms of the RF specific absorption rate in the sperm samples investigated. Although the authors mention that exposure was measured using a calibrated RF detection meter this is of little value in assessing RF exposure in in vitro (or ex vivo) experiments. It is therefore very difficult to discern whether any reported effects are due to the RF exposure or other factors such as heat from the device. The authors do state that heat emanating from the devices may have contributed to the reported effects but this is understating the role of artifact in their experiment given the limitations of exposure assessment.
 
Unfortunately, the study by Chu et al does not seem to add anything to the knowledge base on this subject, and it remains that there is no substantiated evidence that keeping a mobile phone in the pocket affects male fertility.

Based on the abstract, it seems to be a good study with a reasonable conclusion. Studies like this have been performed before, predominantly with older technology mobile networks, so there is some novelty with their use of Wi-Fi, although this mode has also been investigated by other groups.

 
There is some controversy in the field about what is called ‘dosimetry’ in experimental design. This is the science of understanding accurately the level and type of energy that is actually absorbed by the body/tissue/cells from electromagnetic energy sources. Some suggest that the use of a mobile phone unit in these types of experiments, without incorporating accurate field measurements, provide less certainty about the energy that is absorbed by a sample. Again, based on the abstract alone, it’s difficult to understand if this was addressed. The heating of sperm samples is also a very important aspect to stringently control, as we do know that even modest heating of spermatozoa will precipitate motility losses then cell death, independent of any other chemical or physical factor.
 
In any case, sperm motility loss after non-ionising EMR, in-vitro exposure has been well characterised by a number of groups (including our own group), and under a range of electromagnetic energy modes and frequencies. In this regard the groups finding is nothing new and perhaps unsurprising. However, the observation that Wi-Fi EMR impact spermatozoa more than other modes is certainly interesting.
 
Our own research team currently use direct irradiation, or in-vitro exposure type experiments on spermatozoa to investigate the deeper biology of how wireless communication EMR interacts with biology. The caveat with this mode of investigation is that one can not extrapolate the isolated findings to the real world, or to providing commentary on health risk. Nonetheless, it is an important piece of the larger puzzle, and I look forward to seeing the data from this study and further work from the group.

It is impossible to say if this result is caused by the radiofrequency (RF) effects, as the researchers don’t appear to have used strict internationally-recognised protocols for ensuring consistent, measurable and monitored RF doses.

I am one of about 14 experts conducting a WHO systematic review of the effects of RF on male fertility, pregnancy and birth outcomes, including a review of human sperm exposed in vitro. We are about to submit our final report for publication, but we previously published our protocol in Environment International at https://doi.org/10.1016/j.envint.2021.106806. This upcoming review considered several tens of studies on sperm quality and integrity biomarkers and used commonly-accepted Risk of Bias protocols followed by meta-analyses.