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Re: Decline in male gonadal health: nappies not to blame

Dear Editor:

Partsch and colleagues speculate that a rise in testicular temperature in infants and young children consequent to the wearing of modern plastic lined disposable nappies [diapers] may have contributed to both the fall in sperm counts and the increase in testicular cancer which have been reported in some countries.[1] In support of this hypothesis Partsche et al refer to reports of rising incidence rates in testicular cancer.[2-6] These studies report increased cancer risk in men born from before 1900 to 1988 diagnosed up to 1988, from 1916 to 1978, before 1970, from 1907 to 1981, and from 1865 to 1975, respectively. None reports incidence of testicular cancer in men who have had the opportunity to wear modern disposable nappies which have only been widely available since the late 1970s. There is some suggestion that the rise in testicular cancer may not be continuing.[7]

There are no data on testicular cancer incidence in men who are likely to have worn modern disposable nappies as the peak age for this disease is the late 20s and the men are simply too young. Similarly, the reports of a declining sperm count do not include any men born after 1975,[8-11] and even the most recent study from Denmark includes men born only before 1978.[12]

There is no way that modern disposable nappies could have contributed to the changes in male gonadal health reported in men observed to date since all studies are of men who were born before they were available.

Partsch et al[1] claim that the scrotal cooling mechanism was often completely abolished in boys wearing modern disposable nappies. This would appear to be over-interpretation of the data they had available, for two reasons. Firstly, they compared 24-hour mean scrotal temperature with spot rectal temperature and were unable to take into account the considerable circadian variation in core temperature in infants.[13] Secondly, they used measurement techniques validated in adults but not in nappy-wearing infants. They have not demonstrated that their methods, which included covering a considerable portion of the scrotal surface with adhesive tape, did not interfere with two aspects of scrotal cooling, ie, evaporation from the skin surface and contraction and relaxation of the scrotal sac. There is the very real possibility that the measurement process itself increased scrotal temperatures in all children.

There are several inconsistencies in the results table (table 1 in the paper by Partsch et al)[1]; for example, the mean temperatures and the calculated difference between temperatures measured with modern plastic lined disposable nappies and cotton nappies can not be reconciled, which the authors may wish to clarify.[1]

Further scientific research is clearly needed to establish the normal range of temperatures in infant testes and the extent to which they may be affected by different types of nappies and also the extent to which any changes may affect testicular health. However, it is clear that modern plastic lined disposable nappies can have played no role in the changes in male gonadal health reported worldwide to date.

References
1. Partsch C-J, Aukamp M and Sippell WG. Scrotal temperature is increased in disposable plastic lined nappies. Arch Dis Child 2000;83:364-8.

2. Adami H, Bergström R, Möhner M, et al. Testicular cancer in nine northern European countries. Int J Cancer 1994;59:33-8.

3. Forman D, Möller H. Testicular cancer. Cancer Surv 1994;19-20:323-41.

4. Hoff Wanderas E, Tretli S, Fossa SD. Trends in incidence of testicular cancer in Norway 1955-1992. Eur J Cancer 1995;31A:2044-8.

5. Weir HK, Marrett LD, Moravan V. Trends in the incidence of testicular germ cell cancer in Ontario by histologic subgroup, 1964-1996. CMAJ 1999;160:201-5.

6. Zheng T, Holford TR, Ma Z, Ward BA, Flannery J, Boyle P. Continuing increase in incidence of germ-cell testis cancer in young adults: experience from Connecticut, USA, 1035-1992. Int J Cancer 1996;65:723-9.

7. Andersen AG, Jensen TK, Carlsen E, et al. High frequency of sub-optimal semen quality in an unselected population of young men Hum Reprod 2000;15:366-72.

8. Auger J, Kunstmann JM, Czyglik F, Jouannet P. Decline in semen quality among fertile men in Paris during the past 20 years. N Engl J Med 1995;332:281-5.

9. Benshushan A, Shoshani O, Paltiel O, Schenker JG, Lewin A. Is there really a decrease in sperm parameters among healthy young men? A survey of sperm donations during 15 years. J Assist Reprod Genet 1997;14:347-53.

10. Carlsen E, Giwercman A, Keiding N, Skakkebaek NE. Evidence for decreasing quality of semen during past 50 years. BMJ 1992;305:609-13.

11. Irvine S, Cawood E, Richardson D, MacDonald E, Aitken J. Evidence of deteriorating semen quality in the United Kingdom: birth cohort study in 577 men in Scotland over 11 years. BMJ 1996;312:467-71.

12. Pharris-Ciurej ND. Cook LS. Weiss NS. Incidence of testicular cancer in the United States: has the epidemic begun to abate?. Am J Epidemiol 1999;150:45-6.

13. Wailoo MP. Petersen SA. Whittaker H. Goodenough P. Sleeping body temperatures in 3-4 month old infants. Arch Dis Child 1989;64:596-9.

Send letter to journal:
Re: Scrotal temperature: Clarification on methodology

Send letter to journal:
Re: Scrotal insulation

As someone with a long-standing interest in the effects of heat on the testes of farm and experimental animals, I was particularly interested to read the article by Partsch et al (Arch Dis Child 2000;83:364-8) and the accompanying Leading Article (2000;83:281-2) by Professor Hughes. The extent of the temperature elevation produced by the disposable plastic lined nappies is not much less than that of 1.5 to 2.5^oC which we observed in adult male sheep fitted with insulating bags around their scrota (Mieusset et al, Ann NY Acad Sci 1991;637:445-58, and unpublished observations).

This amount of temperature increase applied for as little as 8 hours per day for about 5 months caused appreciable deterioration in semen quality after about 40 days, without much change in sperm numbers, whereas when the bags were applied continuously, sperm motility fell to practically zero within 15 days and numbers fell slightly later. Recovery occurred about 70 days after the end of the insulation.

Furthermore, there was increased embryonic mortality in ewes inseminated with semen collected from insulated rams. Similar results have been reported by others in cattle (Setchell, J Reprod Fertil 1997;114:179-94). As far as I am aware, comparable studies have not been conducted on prepubertal animals, but it would not be difficult to do so.

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Re: Other implications of disposable nappies

Partsch, Aukamp and Sippell propose that increased testicular temperature in early childhood might affect later spermatogenesis. They suggest that 'disposable' nappies could contribute to this and demonstrate a significant difference between the scrotal skin temperature recorded in infants using 'disposable' nappies and washable cotton nappies. They mention in their introductory paragraph that other environmental factors may be important in the deterioration seen in male reproductive health over recent years, but do not relate any of these factors to disposable nappies.[1]

There are many concerns about the use of 'disposable' nappies in addition to increasing scrotal temperature that may impact on future fertility and general health. The 'disposable' nappy consists of a plastic outer layer, a layer of superabsorbant chemicals and inner liner. Nappies are not subject to government controls or independent testing and 'disposable' nappy manufacturers do not need to disclose the contents.[2][3]

Recently concern has been raised about the presence of Tributyl Tin (TBT) in 'disposable' nappies. Greenpeace and Women's Environmental Network have commissioned research which showed that there were significant levels of TBT in many brands of 'disposable' nappy, including those on sale in the UK.[4][5] Babies may be in contact with up to 3.6 times the WHOs estimated tolerable daily intake. TBT is an environmental pollutant which is used in anti-fouling ship paint. It is known to disrupt the endocrine and immune function of marine shellfish and there are international plans to phase out its use.

The superabsorbant chemicals used include sodium polyacrylate crystals which form a gel in contact with urine. This gel can be seen on the skin in contact with it and there are particular concerns about this entering the body through broken skin in the nappy area. Sodium polyacrylate has been removed from tampons as it was associated with the development of Toxic Shock Syndrome.[6] The inner liner has previously been shown to contain nonylphenyl ethoxylate, which acts as an oestrogen mimic, and dioxins.[3]

In addition the use of 'disposable' nappies has important environmental consequences which may impact on child health. Manufacture of 'disposable' nappies uses 3.5 times more energy, 8 times as many non- renewable resources and 90 times as many renewable resources when compared to washable nappies. The description of nappies as disposable is misleading. In this country nappies make up approximately 4% of household waste (800 000 tonnes per year) and every 'disposable' nappy and its contents ever used is still present in a landfill site.[2]

There are environmentally friendly and safe alternatives to the 'disposable' nappy. Modern washable nappies are very different to the traditional idea of buckets of terries. There are now shaped cotton nappies with velcro fastenings, alternatives to nappy pins, breathable covers and disposable paper inner liners. Concern that the incidence of nappy rash is higher with washable nappies is unfounded - it has been shown that it is the length of contact of urine with the skin that is most important in the development of nappy rash[7] and it may be that an infant in a 'disposable' has more chance of developing nappy rash as they are often changed less frequently than an infant in washable nappies. In addition there are cost savings both to individuals and organisations using washable nappies and there have been several successful hospital projects using washable nappies on post natal wards.[2][3]

As paediatricians committed to the health of children we should be aware of the issues raised by the use of 'disposable' nappies, the alternatives that exist and sources of information and support for parents who are concerned about ensuring a safe and sustainable future for their children.

Dr Carrie Heal
Dr Chris Cooper
Consultant Paediatricians, Royal Albert Edward Infirmary, Wigan, UK

References
(1) Partsch C-J, Aukamp, Sippell WG. Scrotal temperature is increased in disposable plastic lined nappies. Arch Dis Child 2000;83:364-8.

(2) Link A. Preventing Nappy Waste Women's Environmental Network 1996.

(3) Sustainable Wales. Dumping the Diaper! Reusable Nappy Report.

(4) Greenpeace. Greenpeace calls on parents to return contaminated nappies to producers: new tests show that TBT-free nappies are a rarity. Press Release 19th May 2000 www.greenpeace.org.

(5) Women's Environmental Network. Press Release 300700. 30th July 2000 www.realnappy.com.

(6) Reingold AL Toxic shock syndrome: an update. Am J Obstet Gynecol 1991;165(4pt2):1236-9.

Send letter to journal:
Re: Re: Scrotal temperature: Clarification on methodology

Dear Editor

Can the scrotal temperature be measured with a conventional thermometer?