authors speculated that use of a wirelessly connected laptop
computer may decrease male fertility potential.
Experts’ comments:
The technological advancements that pervade modern socie-
ty, including cellular telephones, laptop computers, and wire-
less networks, have increased routine exposure of humans to
the electromagnetic fields that are generated by these devices.
In recent years, concerns have arisen over the safety of human
RF-EMW exposure, with investigations of the biological
effects of electromagnetic radiation generating much contro-
versy. Multiple in vitro studies have found significant
decreases in sperm motility and viability as well as increased
reactive oxygen species levels following exposure to RF-EMW
from cellular phones [1,2]. Given the widespread adoption of
Wi-Fi infrastructures in today’s society as well as the com-
paratively higher frequency ranges of RF-EMW that they use
[3]
, similar investigations involving Wi-Fi–connected laptops
are merited.
Avendan
˜o et al. should be commended for providing the
first of such studies. However, certain methodological
limitations within their study design should not be over-
looked. Foremost among these is the intrinsic lack of field
homogeneity underneath the laptop. Although the authors
position their array of specimens such that each is 3 cm
from the computer, the maintenance of a constant distance
from the laptop itself is not sufficient to ensure uniformity
of RF-EMW exposure for each specimen. An improved
approach would involve specifically controlling the dis-
tance from the laptop’s Wi-Fi antenna. Similarly, although
the authors reportedly control for temperature under the
laptop by using an air conditioning system, the nonhomo-
geneous temperature field makes it difficult to entirely
discount thermal effect on the study outcomes. Due to these
design inconsistencies, it might follow that the control
group’s incubation conditions were not precisely identical.
Perhaps a more appropriate control could be achieved by
using the same setup as the experimental group, with the
Wi-Fi signal turned off. As a final point of consideration, the
authors’ inclusion of three teratozoospermic semen sam-
ples within their cohort perhaps influenced the outcomes;
normozoospermic samples would seem to be a logical
starting point for such investigation. The use of more well-
defined exclusion criteria may have better served the study
in this regard.
Despite these apparent methodological shortcomings,
the work done by Avendan
˜o et al. represents the first
extension of RF-EMW investigations to laptops and Wi-Fi,
and its contribution should not be discounted. It is clear that
further, more conclusive studies are warranted in the
ongoing effort to bring clarity to this controversial public
health issue.
Conflicts of interest:
The authors have nothing to disclose.
References
[1] Agarwal A, Desai NR, Makker K, et al. Effects of radiofrequency
electromagnetic waves (RF-EMW) from cellular phones on human
ejaculated semen: an in vitro pilot study. Fertil Steril 2009;92:
1318–25.
[2] De Iuliis GN, Newey RJ, King BV, et al. Mobile phone radiation
induces reactive oxygen species production and DNA damage in
human spermatozoa in vitro. PLoS One 2009;4:e6446.
[3] Gye MC, Park CJ. Effect of electromagnetic ±eld exposure on the
reproductive system. Clin Exp Reprod Med 2012;39:1–9.
Jeremy T. Choy, Robert E. Brannigan
*
Department of Urology, Northwestern University,
Feinberg School of Medicine, Chicago, IL, USA
*Corresponding author.
E-mail address:
r-brannigan@northwestern.edu
(R.E. Brannigan).
Re: Human Semen Quality in the New Millennium:
A Prospective Cross-sectional Population-based Study of
4867 Men
Jørgensen N, Joensen UN, Jensen TK, et al.
BMJ Open 2012;2:e000990
Experts’ summary:
This15-yrprospective study evaluates semen parameters in a
cohort of 4867 Danish men representing the general popula-
tion in Denmark and compares these to two previously stud-
ied cohorts of Danish men. Over the 15-yr period, the authors
found an increase in sperm densities and total sperm counts
with no change in motility and morphology. However, the
authors argue that the contemporary cohort has more men
with suboptimal sperm concentrations, defined as
<
40 mil-
lion/ml, and fewer normal forms than the comparison cohort.
The authors opine that these data put these men at ‘‘high risk
of the need for fertility treatment to become biological
fathers.’’
Experts’ comments:
This work by Jørgensen et al. addresses a long-standing debate
on semen quality that began in 1992 with a meta-analysis in
which Carlsen et al. concluded that sperm counts had de-
creased since the early 1900s
[1]
. The Carlsen data were
subsequently reanalyzed independently using rigorous statis-
tical approaches and demonstrated either no changes or
increases in sperm counts over time
[2]
. Numerous other
studies evaluating temporal trends in semen parameters have
mostly agreed with these latter interpretations (unpubl. data,
A. Pastuszak). However, the majority of these subsequent stud-
ies, as well as the studies analyzed by Carlsen et al.
[1]
,
are retrospective; therefore, confounding factors, including
semen analysis methods, abstinence periods, and selection
biases, were poorly controlled. This current study, a prospective
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