Infertility affects approximately one in six couples worldwide. More than half the time, it is the man's low sperm quality that is to blame. Over the last three decades, sperm quality seems to have declined for no clearly identifiable reason. Theories are running rampant without anyone having the proof to back them up.
Potential Causes
The environment, lifestyle, excess weight or obesity, smoking, alcohol consumption, and psychological stress have all been alternately offered up as potential causes, following low-quality epidemiological studies. Cellphones are not exempt from this list, due to their emission of high-frequency (800-2200 MHz) electromagnetic waves that can be absorbed by the body.
Clinical trials conducted in rats or mice suggest that these waves can affect sperm quality and lead to histological changes to the testicles, bearing in mind that the conditions met in these trials are very far from our day-to-day exposure to electromagnetic waves, mostly via our cellphones.
The same observation can be made about experiments conducted on human sperm in vitro, but changes to the latter caused by electromagnetic waves leave doubts. Observational studies are rare, carried out in small cohorts, and marred by largely conflicting results. Publication bias plays a major role, just as much as the abundance of potential confounding factors does.
Swiss Observational Study
An observational study carried out in Switzerland had the benefit of involving a large cohort of 2886 young men who were representative of the general population. The participants completed an online questionnaire describing their relationship with their cellphone in detail and in qualitative and quantitative terms.
The study was launched in 2005, before cellphone use became so widespread, and this timeline was considered when looking for a link between cellphone exposure and sperm quality. In addition, multiple adjustments were made in the multivariate analyses to account for as many potential confounding factors as possible.
The participants, aged between 18 and 22 years, were recruited during a 3-day period to assess their suitability for military service. Each year, this cohort makes up 97% of the male population in Switzerland in this age range, with the remaining 3% being excluded from the selection process due to disability or chronic illness.
Regardless of the review board's decision, subjects wishing to take part in the study were given a detailed description of what it involved, a consent form, and two questionnaires. The first focused on the individual directly, asking questions about his health and lifestyle. The second, intended for his parents, dealt with the period before conception.
This recruitment, which took place between September 2005 and November 2018, involved the researchers contacting 106,924 men. Ultimately, only 5.3% of subjects contacted returned the completed documentation. In the end, the study involved 2886 participants (3.1%) who provided all the necessary information, especially the laboratory testing (including a sperm analysis) needed to meet the study objectives. The number of hours spent on a smartphone and how it was used were routinely considered, as was sperm quality (volume, concentration, and total sperm count, as well as sperm mobility and morphology).
Significant Associations
A data analysis using an adjusted linear model revealed a significant association between frequent phone use (> 20 times per day) and lower sperm concentration (in mL) (adjusted β: -0.152, 95% CI -0.316 to 0.011). The same was found for their total concentration in ejaculate (adjusted β: -0.271, 95% CI -0.515 to -0.027).
An adjusted logistic regression analysis estimated that the risk for subnormal male fertility levels, as determined by the World Health Organization (WHO), was increased by at most 30%, when referring to the concentration of sperm per mL (21% in terms of total concentration). This inverse link was shown to be more pronounced during the first phase of the study (2005-2007), compared with the other two phases (2008-2011 and 2012-2018). Yet no links involving sperm mobility or morphology were found, and carrying a cellphone in a trouser pocket had no impact on the results.
This study certainly involves a large cohort of nearly 3000 young men. It is, nonetheless, retrospective, and its methodology, despite being better than that of previous studies, is still open to criticism. Its results can only fuel hypotheses, nothing more. Only prospective cohort studies will allow conclusions to be drawn and, in the meantime, no causal link can be found between exposure to the high-frequency electromagnetic waves emitted by cellphones and the risk of infertility.
This article was translated from JIM, which is part of the Medscape professional network.
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