No, mobile phones are not ‘cooking’ men’s sperm

Men who keep their mobile phone in their pockets are ‘cooking’ their sperm, lowering their gamete count and raising the risk of fertility problems, according to a study published in Reproductive BioMedicine.

Unfortunately, the claims are not borne out by the evidence (see our expert verdict below).

The researchers, from the Technion University in Israel, said that while 11 per cent of their study group were ‘seriously affected’ by fertility problems, this figure jumped to 47 per cent in men who kept their phones too close — which they defined as within 19 inches — to their testicles.

They also warned against speaking on the phone while it is charging, and leaving it on a bedside table overnight.

The researchers collected data from 106 men who attended a fertility clinic for at least one year. Semen quality was assessed by analysing volume, concentration, motility (ability to move properly) and morphology (the number of abnormally shaped spermatozoa). Participants also answered a questionnaire about their mobile phone usage. The study concluded that the effects they observed could lower sperm levels to the point that conception could become difficult.

Professor Martha Dirnfeld, one of the study’s authors, said: ‘We analysed the amount of active swimming sperm and the quality and found that it had been reduced. We think this is being caused by a heating of the sperm from the phone and by electromagnetic activity.

‘I think this is a warning to men to change their habits to improve their chances of having children. Women generally don’t carry their mobiles on them so maybe a mobile phone won’t affect their fertility. That’s not something we have looked at.’

Expert verdict
This is a bad piece of research for a number of reasons.

The sample size is small and does not reflect the general population — 100 guys who had all been referred to a fertility clinic (the study eventually only involved 80 people). The further ‘evidence’ the study cites shares the same problem. There isn’t anywhere near the statistical power here to make the numbers stand up.

No clear mechanisms for how this is supposed to work are postulated. Amusingly, one of the papers admits that ‘scrotal hyperthermia’ and ‘oxidative stress’ are the main mechanisms of damage, accepting that other, bigger explanations exist.

A lot of good research (for instance here) has been done on electromagnetic fields and health. No risk has been established so far.

The paper points out that sperm counts have nearly halved over 50 years and the rate of decline has been roughly steady. However, mobile phones have only widely been available since the mid-90s. There hasn’t been an appreciable dip in sperm count since then. This may be a result of the oral contraceptive pill leaching into the water supply and suppressing male hormone/sperm production. But that’s for another day.

Research score: 1/5.


  • red2black

    Women seem to prefer them raw.

    • Dave

      They also have the benefit of a testicle further away from the phone and one nearer also…

      • red2black

        I’ve been instructed to carry my phone in alternate pockets on alternate days, in order to achieve an even bake, which is arrived at in conjunction with the pot being brought to the boil.

  • sidor

    I wonder if the “expert” looked into the study he refers to. I did. This is what it says:

    “The Reflex project studied how low-energy EMF
    interacts directly with biological materials in the
    laboratory (in vitro). The researchers showed that
    exposing cells to ELF and RF electromagnetic
    fields could cause DNA to break apart and thus
    affect how cells develop. “

  • Dave

    Exactly. In Vitro – and if you read around that segment, you will see that they even say that the subject remains contentious, as there is variable evidence on whether this is relevant or not. DNA splitting occurs in a lot of everyday situations – sunlight, exposure to environmental factors, and so on. That isn’t clear evidence of concern; the body has a way of repairing this splitting – it is a laboratory finding where people wanted to prove a theory, and one of the reasons why “cancer clusters around power lines” continues to be discussed despite a lack of evidence to suggest they do contribute to the issue. Happy to wait and see what the in vivo epidemiology suggests on reasonably sized population data; not a couple of guys in a fertility clinic asked if they use mobiles. Considering the exposure to mobile phones, I’d say we’re all “screwed”, right? Interesting to see the data on mobile phones causing brain cancer is similarly lacking in conclusive evidence.

  • Janette

    I would say that it is rather fortunate that the claims are ‘untrue’, not, as your writer expresses it: ‘Unfortunately, the claims are not borne out by the evidence….’