1 Department of Urology and 3 General Clinical Research Center, State University of New York at Stony Brook, Stony Brook NY 11794-8093, USA
2 To whom correspondence should be addressed at: Department of Urology, SUNY at Stony Brook, HSC level 9 room 040, Stony Brook NY 11794-8093, USA. Email: ysheynkin{at}notes.cc.sunysb.edu
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Testicular function is temperature dependent and requires a temperature 24°C below body temperature (Thonneau et al., 1998). Elevated testicular temperature is a well-documented mechanism of abnormal spermatogenesis in common diseases associated with male infertility, e.g. varicocele, undescended testis (Mieusset et al., 1985
; Goldstein and Eid, 1989
; Lerchl et al., 1993
; Wright et al., 1997
).
Numerous factors can elevate scrotal temperature either by whole body or local scrotal heating. Elevated scrotal temperature was found in men with febrile illness, retractile testes, occupations associated with high temperature exposure, hot bath and sauna users, men wearing tight jockey shorts and suspensories, car drivers (Mills, 1919; MacLeod, 1951
; Kapadia and Phadke, 1955
; Robinson and Rock, 1967
; Brindley, 1982
; Brown-Woodman et al., 1984
; Nistal and Paniagua, 1984
; Rubben et al., 1986; Figa-Talamanca et al., 1992
; Saikhun et al., 1999
; Bujan et al., 2000
). Multiple human studies have confirmed deleterious effects of scrotal hyperthermia on spermatogenesis (Rock and Robinson, 1965
; Robinson et al., 1968
; Mieusset and Bujan, 1995
; Kandeel and Swerdloff, 1988
).
Local scrotal hyperthermia can be achieved by direct heat exposure or effect of body temperature and blunted physiological testicular cooling mechanism (Kapadia and Phadke, 1955; Robinson and Rock, 1967
; Brindley, 1982
).These factors have been experimentally studied by various methods including local scrotal hot water bath, direct heating with a 150 Wt electric light bulb, sitting position with thighs approximated to the scrotum, and scrotal insulation (Rock and Robinson, 1965
; Robinson et al., 1968
; Brindley, 1982
). Recently potential exposure of male reproductive function to certain lifestyle factors (sedentary work position, prolonged car driving, wearing plastic lined diapers by children) has been linked to increased scrotal temperature and delayed conception (Bujan et al., 2000
; Hjollund et al., 2000
, 2002a
; Partsch et al., 2000
).
Continued improvements in power, size and price of LC have favored their increased use in a younger population of reproductive age. However, LC actively generate heat and can reach internal operating temperature >70°C. Frequently positioned close to the scrotum, this device is capable of producing direct local heat exposure. In addition, the use of a LC requires a special body position in order to balance the computer on a lap when the scrotum is trapped between closely approximated thighs.
With the exception of an anecdotal report of penile and scrotal burns after LC use (Ostenson, 2002), the effect of portable computers in a laptop position on scrotal temperature is not known. We performed the first study to investigate scrotal temperature changes in LC users.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Body temperature was taken orally prior to each session. Each participant spent 15 min standing in the room to adjust to the room temperature before being seated in the chair. Two cutaneous thermocouples (5SRTC-TT J type Teflon insulated wire, Omega Engineering Inc., Stamford, CT; maximum service temperature of 260°C) were attached to the unshaved scrotal skin anteriorly corresponding to the right and left testis using thin transparent tape to cover the sensor end of the thermocouple. Nonworking LC was positioned on the lap. After the participant adopted the position with approximated thighs necessary to comfortably balance the LC on the lap, the LC was removed. This position was maintained throughout the complete session. The thermocouples were connected to digital thermometer/datalogger HH84 (Omega Engineering Inc., Stamford, CT). Separate measurements of scrotal temperature on the right and left side were recorded in 3 min intervals. The datalogger was calibrated daily.
Two different brand name Pentium 4 LC were used randomly. The LC was turned on for 15 min before being positioned on the lap. Thermocouples were attached the same way and at the same place on the right and left side of the scrotum. Then the LC was comfortably positioned on the lap and the participant adopted and maintained the same sitting posture as at the previous session without the LC. Temperature measurements were performed at 3 min intervals. Measurements of the external bottom surface temperature of the working LC were taken randomly at the same time intervals.
Statistical analysis
Statistical analysis was carried out in SAS version 8.2 (SAS Institute Inc, Cary, NC). Data are summarized with medians and ranges (min and max) in centigrade units. Wilcoxon signed-ranks tests for two related samples were used to test for differences between scrotal temperatures for each side separately with P<0.05 considered statistically significant.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Heat remains one of the most critical and unresolved issues in computer design. Frequent use of LC in a laptop position directly exposes the scrotum to the dissipated high internal operating temperature of the machine.
Maintenance of a proper testicular temperature is essential for normal spermatogenesis. Our study demonstrates statistically significant elevation of scrotal temperature in LC users. Since scrotal skin temperature strongly correlates with testicular temperature, such elevation corresponds to a testicular hyperthermia (Kitayama, 1965; Kurz and Goldstein, 1986
; Hjollund et al., 2002a
). Portable computers in a laptop position produce scrotal hyperthermia by both the direct heating effect of the computer and the sitting position necessary to balance computer on the lap with the scrotum trapped tightly between the thighs. Increased scrotal temperature in a sitting position with thighs together has been reported in previous studies (Rock and Robinson, 1965
; Brindley, 1982
; Bujan et al., 2000
). However, the thermal impact of working LC in a laptop position is significantly higher than positional scrotal hyperthermia itself.
In our study, median left and right side scrotal temperature increase in the group with working LC was 2.6°C and 2.8°C, respectively. The magnitude of scrotal hyperthermia associated with abnormal spermatogenesis is unclear. While an increase in scrotal temperature of 1°C was sufficient to suppress spermatogenesis in some studies, others did not confirm those findings when scrotal temperature rose by 0.81°C (Rock and Robinson, 1965; Wang et al., 1997
). Higher testicular or scrotal temperature elevation between 1 and 2.9°C was more consistently associated with a sustained and considerable negative effect on spermatogenesis and fertility (Robinson et al., 1968
; Zorgniotti and MacLeod, 1973
; Mieusset et al., 1985
; Shafik, 1991
). Therefore, a scrotal temperature increase of more than 1°C above baseline has been suggested as a possible minimal thermal gradient capable of inhibiting spermatogenesis (Wang et al., 1997
; Partsch, 2000
). A strong negative association was found between high scrotal temperature and sperm count as well as Inhibin B, which is considered a biochemical marker of spermatogenesis. Sperm concentration decreased by 40% per 1°C increment of median daytime scrotal temperature (Hjollund et al., 2002b
). In one animal study, an increase in scrotal temperature resulted in impaired fertility even without any detectable changes in semen analysis (Mieusset et al., 1992
).
The frequency and time of heat exposure capable of producing reversible or irreversible changes in human spermatogenesis are not known. Studies of frequency of heat exposure and durability of inhibition of spermatogenesis revealed significant but reversible (within weeks or months) changes after single or multiple short-term scrotal heating (Robinson et al., 1968; Kandeel and Swerdloff, 1988
) and total body heating (Procope, 1965
; Brown-Woodman et al., 1984
). However, LC may produce significant repetitive transient scrotal hyperthermia for years. Insufficient recovery time between heat exposures may cause irreversible or partially reversible changes in male reproductive function. In one study, men exposed to high temperature for 57 years were found to have oligoasthenoteratozoospermia, while those exposed for 1215 years had azoospermia (Dada et al., 2003
). Another study of 449 male partners of infertile couples revealed that patients with idiopathic oligoasthenoteratozoospermia are more exposed to genital heat stress than normozoospermic men (Jung et al., 2002
).
Our study demonstrates that working with a LC produces significant elevation of scrotal temperature. While scientific background suggests a negative impact of scrotal hyperthermia upon spermatogenesis, further studies of this particular type of thermal exposure with LC are warranted. Meanwhile, limited use of LC in a laptop position by teenage boys and young men in reproductive age may be considered, to avoid intermittent scrotal heat exposure.
![]() |
Acknowledgements |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Brown-Woodman PD, Post EJ, Glass GC and White IG (1984) The effect of a single sauna exposure on spermatozoa. Arch Androl 12, 915.[ISI][Medline]
Bujan L, Daudin M, Charlet JP, Thonneau P and Mieusset R (2000) Increase in scrotal temperature in car drivers. Hum Reprod 15, 13551357.
Carlsen E, Giwercman A, Keiding N and Skakkebæk NE (1992) Evidence for decreasing quality of semen during past 50 years. Br Med J 305, 609613.[ISI][Medline]
Dada R, Gupta NP and Kucheria K (2003) Spermatogenic arrest in men with testicular hyperthermia. Teratogen Carcinogen Mutagen (Suppl 1), 235243.
Figa-Talamanca I, Dell'Orco V, Pupi A et al. (1992) Fertility and semen quality of workers exposed to high temperatures in the ceramics industry. Reprod Toxicol 6, 517523.[CrossRef][ISI][Medline]
Fisch H, Goluboff ET, Olson JH, Feldshuh J, Broder SJ and Barad DH (1996) Semen analyses in 1,283 men from the United States over a 25-year period: no decline in quality. Fertil Steril 65, 10091014.[ISI][Medline]
Gilbaugh JH and Lipshultz LI (1994) Nonsurgical treatment of male infertility. Urol Clin N Amer 21, 531548.[ISI][Medline]
Goldstein M and Eid JF (1989) Elevation of Intratesticular and scrotal skin surface temperature in men with varicocele. J Urol 142, 743745.[ISI][Medline]
Hjollund NHI, Bonde JPE, Jensen TK and Olsen J (2000) Diurnal scrotal skin temperature and semen quality. Int J Androl 23, 309318.[CrossRef][ISI][Medline]
Hjollund NHI, Storgaard L, Ernst E, Bonde JP and Olsen J (2002a) The relationship between daily activities and scrotal temperature. Hum Reprod 16, 209214.[ISI]
Hjollund NHI, Storgaard L, Ernst E, Bonde JP and Olsen J (2002b) Impact of diurnal scrotal temperature on semen quality. Hum Reprod 16, 215221.[CrossRef][ISI]
Jegou B, Auger J, Multinger L et al. (1999) The saga of the sperm count decrease in humans, wild and farm animals. In Gagnon C (ed.) The Male Gamete, from Basic Science to Clinical Applications. Cache River Press, USA, pp. 445454.
Jung A, Schill WB and Schuppe HC (2002) Genital heat stress in men of barren couples:a prospective evaluation by means of a questionnaire. Andrologia 34, 349355.[CrossRef][ISI][Medline]
Kandeel FR and Swerdloff RS (1988) Role of temperature in regulation of spermatogenesis and the use of heating as a method for contraception. Fertil Steril 49, 149.[ISI][Medline]
Kapadia RM and Phadke AM (1955) Scrotal suspenders and subfertility. J Fam Welf 2, 27.
Kitayama T (1965) Study on testicular temperature in men. Hinjokika Kiyo 11, 435465.
Kurz KR and Goldstein M (1986) Scrotal Temperature reflects Intratesticular temperature and is lowered by shaving. J Urol 135, 290292.[ISI][Medline]
Lerchl A and Nieschlag E (1996) Decreasing sperm counts? A critical review. Exp Clin Endocrinol Diabetes 104, 301307.[ISI][Medline]
Lerchl A, Keck C, Spiteri-Grech J and Nieschlag E (1993) Diurnal variations in scrotal temperature of normal men and patients with varicocele before and after treatment. Int J Androl 16, 195200.[ISI][Medline]
MacLeod J (1951) Effect of chicken pox and pneumonia on semen quality. Fertil Steril 2, 523533.[ISI]
Mieusset R and Bujan L (1995) Testicular heating and its possible contribution to male infertility: a review. Int J Androl 18, 169184.[ISI][Medline]
Mieusset R, Grandjean H, Mansat A and Pontonnier F (1985) Inhibiting effect of artificial cryptorchidism on spermatogenesis. Fertil Steril 43, 589594.[ISI][Medline]
Mieusset R, Quintana-Casares P, Sanchez-Partida LG et al. (1992) Effects of heating the testes and epididymides of rams by scrotal insulation on fertility and embryonic mortality in ewes inseminated with frozen semen. J Reprod Fert 94, 337343.[ISI][Medline]
Mills RG (1919) The pathological changes in the testes in epidemic pneumonia. J Exp Med 30, 505528.
Nistal M and Paniagua R (1984) Infertility in adult males with retractile testes. Fertil Steril 41, 395403.[ISI][Medline]
Olsen GW, Bodner KM and Ramlow JM (1995) Have sperm counts been reduced 50 percent in 50 years? A statistical model revisited. Fertil Steril 63, 887893.[ISI][Medline]
Ostenson C-G (2002) Lap burn due to laptop computer. Lancet 360, 1704.[Medline]
Partsch C-J, Aukamp M and Sippell WG (2000) Scrotal temperature is increased in disposable plastic lined nappies. Arch Dis Child 83, 364368.
Procope BJ (1965) Effect of repeated increase of body temperature on human sperm cells. Int J Fertil 10, 333339.[ISI][Medline]
Rozati R, Reddy PP, Reddanna P and Mujtaba R (2002) Role of environmental estrogens in the deterioration of male factor fertility. Fertil Steril 78, 11871194.[CrossRef][ISI][Medline]
Robinson D and Rock J (1967) Intrascrotal hyperthermia induced by scrotal insulation: effect on spermatogenesis. Obstet Gynecol 2, 217223.
Robinson D, Rock J and Menkin MF (1968) Control of Human Spermatogenesis by Induced Changes of Intrascrotal Temperature. JAMA 204, 8087.[CrossRef][Medline]
Rock J and Robinson D (1965) Effect of induced intrascrotal hyperthermia on testicular function in man. Am J Obstet Gynecol 93, 793801.[ISI][Medline]
Rübben H, Recker F and Lutzeyer W (1986) Exogene Wärmeexpositioneine Ursache der Subfertalität. Urologe 25, 6768.[ISI][Medline]
Saikhun J, Kitiyanant Y, Vanadurongwan V and Pavasuthipasit K (1999) Effects of sauna on sperm movement characteristics of normal men measured by computer-assisted sperm analysis. Int J Androl 6, 358363.
Shafik A (1991) Testicular suspension as a method of male contraception: technique and results. Adv Contrac Deliv Syst 7, 269279.
Swan SH, Elkin EP and Fenster L (1997) Have sperm densities declined? A reanalysis of global trend data. Env Health Perspect 105, 12281232.[ISI]
Thonneau P, Bujan L, Multingner L and Mieusset R (1998) Occupational heat exposure and male fertility: a review. Hum Reprod 13, 21222125.[Abstract]
Toppari J, Latsen JC, Christiansen P et al. (1996) Male reproductive function and environmental xenoestrogens. Environ Health Perspect 104, 741803.[ISI][Medline]
Wang C, McDonald V, Leung A et al. (1997) Effect of increased scrotal temperature on sperm production in normal men. Fertil Steril 68, 334339.[CrossRef][ISI][Medline]
Wright EJ, Young GPH and Goldstein M (1997) Reduction in testicular temperature after varicocelectomy in infertile men. Urology 2, 257259.
Zorgniotti AW and MacLeod J (1973) Studies in temperature, human semen quality and varicocele. Fertil Steril 24, 854863.[ISI][Medline]
Submitted on May 4, 2004; resubmitted on September 27, 2004; accepted on October 21, 2004.
|