Scientists are probing whether electromagnetic radiation emitted by mobile phones affects semen quality in a research project launched this year, after a study associated frequent cellphone use with a lower sperm count.
While various environmental and lifestyle factors have been proposed to explain the decline in semen quality observed over the past 50 years, the role of cellphones has yet to be demonstrated.
Although a major cross-sectional study on the subject by a team from the University of Geneva (UNIGE), in collaboration with the Swiss Tropical and Public Health Institute (Swiss TPH), linked frequent phone use with a lower sperm concentration and total sperm count, the researchers did not, however, find any association between mobile phone use and low sperm motility and morphology.
Their findings were published in Fertility & Sterility.
Semen quality is determined by the assessment of parameters such as sperm concentration, total sperm count, sperm motility and sperm morphology.
According to the values established by the WHO, a man will most probably take more than one year to conceive a child if his sperm concentration is below 15m per millilitre. In addition, the percentage chance of pregnancy will decrease if the sperm concentration is below 40m per millilitre.
Many studies have shown that semen quality has decreased over the past 50 years. Sperm count is reported to have dropped from an average of 99m sperm per millilitre to 47m per millilitre – thought to be the result of a combination of environmental factors (endocrine disruptors, pesticides, radiation) and lifestyle habits (diet, alcohol, stress, smoking).
Assessing the impact of phones
Is the mobile phone also to blame? After conducting the first national study (2019) on the semen quality of young men in Switzerland, a team from UNIGE undertook the largest ever cross-sectional study on this topic.
It is based on data from 2 886 Swiss men aged 18 to 22, recruited between 2005 and 2018 at six military conscription centres.
In collaboration with the TPH, the scientists studied the association between semen parameters of 2 886 men and their use of phones.
“Men completed a detailed questionnaire related to their lifestyle habits, their general health status and more specifically the frequency at which they used their phones, as well as where they placed it when not in use,” said Serge Nef, full professor in the Department of Genetic Medicine and Development at the UNIGE Faculty of Medicine and at the SCAHT – Swiss Centre for Applied Human Toxicology, who co-directed the study.
These data revealed an association between frequent use and lower sperm concentration. The median sperm concentration was significantly higher in the group of men who did not use their phone more than once a week (56.5 million/mL) compared with men who used their phone more than 20 times a day (44.5 million/mL).
This difference corresponds to a 21% decrease in sperm concentration for frequent users (>20 times/day) compared to rare users (<1 time>
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This inverse association was found to be more pronounced in the first study period (2005-2007) and gradually decreased with time (2008-2011 and 2012-2018).
“This trend corresponds to the transition from 2G to 3G, and then from 3G to 4G, that has led to a reduction in the transmitting power of phones,” said Martin RÖÖsli, associate professor at Swiss TPH.
“Previous studies evaluating the relationship between the use of phones and semen quality were performed on a relatively small number of individuals, rarely considering lifestyle information, and have been subject to selection bias, as they were recruited in fertility clinics.
“This has led to inconclusive results,” said Rita Rahban, senior researcher and teaching assistant in the Department of Genetic Medicine and Development in the Faculty of Medicine at the UNIGE and at the SCAHT, first author and co-leader of the study.
It doesn’t matter where you put your phone
Data analysis also seems to show that the position of the phone – for example, in a trouser pocket – was not associated with lower semen parameters.
“However, the number of people in this cohort who did not carry their phone close to their body was too small to draw a really robust conclusion on this specific point,” added Rahban.
This study, like most epidemiologic studies investigating the effects of cellphone use on semen quality, relied on self-reported data, which is a limitation. By doing so, the frequency of use reported by the individual was assumed to be an accurate estimate of exposure to electromagnetic radiation.
To address this limitation, a study funded by the Federal Office for the Environment (FOEN) was launched this year. Its aim is to directly and accurately measure exposure to electromagnetic waves, as well as the types of use – calls, web navigation, sending messages – and to assess their impact on male reproductive health and fertility potential.
The data will be collected using an application that each future participant will download to their mobile phone. The research team is actively recruiting participants for this study.
The aim is also to better describe the mechanism of action behind these observations.
“Do the microwaves emitted by phones have a direct or indirect effect? Do they cause a significant increase in temperature in the testes? Do they affect the hormonal regulation of sperm production? This all remains to be discovered,” said Rahban.
Study details
Association between self-reported mobile phone use and the semen quality of young men
Rita Rahban, Alfred Senn, Serge Nef, Martin Rӧӧsli.
Published in Fertility and Sterility on 31 October 2023
Objectives
To investigate the association between mobile phone exposure and semen parameters.
Design
A nationwide cross-sectional study.
Setting
Andrology laboratories in close proximity to six army recruitment centres.
Patients
In total, 2 886 men from the general Swiss population, 18–22 years old, were recruited between 2005 and 2018 during military conscription.
Intervention
Participants delivered a semen sample and completed a questionnaire on health and lifestyle, including the number of hours they spent using their mobile phones and where they placed them when not in use.
Main Outcome Measures
Using logistic and multiple linear regression models, adjusted odds ratios and β coefficients were determined, respectively. The association between mobile phone exposure and semen parameters such as volume, sperm concentration, total sperm count (TSC), motility, and morphology was then evaluated.
Results
A total of 2 759 men answered the question concerning their mobile phone use, and 2 764 gave details on the position of their mobile phone when not in use. In the adjusted linear model, a higher frequency of mobile phone use (>20 times per day) was associated with a lower sperm concentration (adjusted β: −0.152; 95% confidence interval: −0.316; 0.011) and a lower TSC (adjusted β: −0.271; 95% confidence interval: −0.515; −0.027). In the adjusted logistic regression model, this translates to a 30% and 21% increased risk for sperm concentration and TSC to be below the World Health Organization reference values for fertile men, respectively. This inverse association was found to be more pronounced in the first study period (2005–2007) and gradually decreased with time (2008–2011 and 2012–2018). No consistent associations were observed between mobile phone use and sperm motility or sperm morphology. Keeping a mobile phone in the pants pocket was not found to be associated with lower semen parameters.
Conclusion
This large population-based study suggests that higher mobile phone use is associated with lower sperm concentration and TSC. The observed time trend of decreasing association is in line with the transition to new technologies and the corresponding decrease in mobile phone output power. Prospective studies with improved exposure assessment are needed to confirm whether the observed associations are causal.
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