"...chemicals in disposables and the heat they generate for boys around their bits which can result in infertility..."
Disposables generate heat??? Doubt it. Is she claiming an exothermic reaction between urine and nappy material? I dare say that sounds a bit far fetched.
Sorry, Ewila but the orginal poster was correct! 
This is from the Archives of disease in childhood. (But do note that whilst some studies support thsi research, there is other research which disputes the testicular cancer link).
Other implications of disposable nappies
HEAL, C; COOPER, C Consultant Paediatricians
Royal Albert Edward Infirmary, Wigan Lane, Wigan WW1 2NN, UK
Editor,—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 superabsorbent 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 WHO's 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 superabsorbent 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, along with other chemical constituents that increase absorbency, 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 with washable nappies. The description of such 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 from 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 postnatal 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.