Abbreviation:AGM absorbent gelling material
During the past two decades, use of disposable diapers has grown substantially. At present, more than 90% of diapers used in developed nations are disposable (Procter & Gamble, Unpublished data). Diaper technology has advanced significantly during the last decade, and efforts continue to focus on eliminating leaking and skin irritation associated with diaper use. The impact that technological innovations have had on the frequency and severity of diaper dermatitis has not been yet been studied systematically, but ample data relate to the safety of the newer agents used in these diapers to increase absorbancy and decrease irritation and leaking. An historical perspective supports the premise that innovations in disposable diaper design and materials have played an important role in reducing leaking with its concommittant infectious risk. It also appears that the prevalence of the more severe forms of irritant contact dermatitis in the diaper area have decreased concurrent with the increased utilization of disposable diapers.
It was initially postulated that fecal microflora in the diaper area converted urea to ammonia, which then provoked diaper dermatitis . Leyden et al. refuted this ammonia hypothesis and triggered a vigorous re-examination of the diaper-associated variables that play an etiological role in this condition. Berg [3,4] and others [5,6] were instrumental in the development of a model that convincingly explains how diapers can interact with skin to cause diaper dermatitis. Specifically, this model proposed that irritant diaper dermatitis is the result of a cascade of events that occur when the skin is exposed to overhydration, frictional damage, and the increased pH of the urine and feces mixture (with resulting enhanced activity of fecal enzymes). Acting in concert, these variables weaken the barrier function of the stratum corneum, facilitate irritant penetration, and trigger the inflammatory and repair mechanisms that ultimately bring about the erythema, papules, erosions, and scale characteristic of this condition .
A lasting influence of this diaper dermatitis model has been the road map it provided to guide innovations in disposable diaper design (Fig. 1) . In particular, efforts were focused toward achieving material and design innovations to reduce skin hydration, maintain a lower skin pH in the diaper covered area, and incorporate materials with lower potential to cause abrasion and frictional damage. The significant advances in absorption and containment also yielded other important collateral benefits. Prominent among them was the recognition that these improved diapers reduced fecal and bacterial contamination in day care centers [9,10]. Such environmental contamination in child care settings is directly associated with the incidence of diarrhea in such environments . These documented advantages of disposable diapers, coupled with the significant convenience factor they offer have made them the preferred mode of waste containment in early childhood in Western nations and, increasingly, in the developing world as well.
Superabsorbent disposable diapers
One of the most significant developments in disposable diaper technology was the advent of cross-linked sodium polyacrylate polymers (absorbent gelling materials, AGM) as the main absorbent component in the diaper core. These materials have the capacity to absorb many times their weight in fluid, and, when hydrated, form a gel that keeps the fluid stored away from the skin, within the diaper core. These superabsorbant polymers constitute the single most important advance in reducing skin overhydration under the diaper. Initial clinical evaluations of AGM materials showed improvements in diaper-dependent variables known to play a key etiological role in diaper dermatitis such as skin overhydration, pH, and friction . Consistent with Berg’s  diaper dermatitis model, clinical trials conducted in North America [13,14] and Western Europe [15–17] also documented statistically significant reductions in frequency and severity of diaper dermatitis in users of AGM diapers compared with either cloth or cellulose-only disposable diapers.
Healthcare providers have suspected that there is a temporal association between the introduction of superabsorbent diapers and a reduction in incidence of the more severe forms of diaper dermatitis. A retrospective evaluation of numerous clinical trials was performed to determine whether the incidence and severity of diaper dermatitis changed following the widespread use of AGM diapers became commonplace. Specifically, 12 clinical trials (Procter & Gamble, Unpublished data) were reviewed, six of which were conducted before and six after the advent of superabsorbent polymers. Data from the initial examination of each child was obtained while he or she was wearing his routine diaper. These baseline results were compiled across the six studies conducted in each of the two periods of interest (ie, pre-and post-AGM diapers) to increase the overall base size for the comparison and to reduce the risk of biases caused by seasonal, geographic, or other possible confounding variables. Clearly, this approach does not constitute a rigorously controlled epidemiological study. However, it does provide a broad snapshot view of diaper area skin spanning multiple years and geographic areas, and a total of nearly 4000 children. As such, it offers a data-based perspective to evaluate the proposition that the severity of diaper dermatitis declined after the introduction of super absorbent diapers.
The results of this evaluation are summarized in Figure 2. The frequency of moderate to severe diaper dermatitis declined by 50% in the post-AGM period. In addition, the number of normal diaper skin exams nearly doubled following the introduction of AGM diapers. In our view, this base of evidence supports the proposition that the reduction in skin overhydration made possible with the advent of super absorbent polymers is associated with a reduction in prevalence of the more severe forms of diaper dermatitis.
Because children spend several years in close contact with diaper materials, the safety of absorbent gelling materials has been thoroughly evaluated in more than 400 studies . These studies confirm that AGM does not produce skin irritation or allergies, and is nonmutagenic and nongenotoxic . Absorbent gelling material is also safe if accidentally swallowed. Animal studies have shown that AGM passes harmlessly through the gastrointestinal tract with few effects noted other than mild diarrhea. In addition, AGM in diapers does not generate breathable particles and therefore does not pose a risk for respiratory irritation .
Recent developments in disposable diapers and diaper area care
Advances in the plastics and fabrics industries have made available new polymeric covers or films which allow a moisture vapor flux while remaining virtually impermeable to liquid water. These materials are being applied as disposable diaper backsheets (the outermost cover of the diaper) to enable moisture vapor to flow from the inside (higher moisture) to the outside (lower moisture) of the diaper, rather than remaining trapped within the absorbent core. These novel outer covers, usually called breathable backsheets constitute another important development in diaper technology that is helping reduce skin overhydration. As use of these newer materials becomes widespread, superabsorbent diaper cores and breathable backsheets can be expected to reduce to a minimum the problem of skin overhydration in the diaper area.
A more recent, significant development has been the introduction of disposable diapers with an inner liner designed to deliver a petrolatum-based formulation to the child’s skin continuously during use. The petrolatum formulation is applied to the liner in such a way that absorbency is not compromised. The diaper therefore retains its primary function, while taking advantage of the continuous, close contact between liner and skin as a means to deliver an active ingredient (petrolatum) known to protect against hydration and irritation [20–22]. Recent reports have documented the feasibility of achieving continuous topical delivery of petrolatum by this means  and demonstrated the advantages of this novel diaper in terms of improving the condition of diapered skin .
The first reported evaluation of this petrolatum-containing diaper  was conducted among children who had no particular propensity for diaper dermatitis (all comers). A second clinical trial (Procter & Gamble, Unpublished data) was subsequently conducted which evaluated this diaper among a cohort of children deemed by their parents to be especially susceptible to diaper dermatitis (ie, rash prone). Using a double blind, randomized design, the children were assigned to use the petrolatum-containing diaper or an identical control product lacking the formulation for 6 weeks, and were evaluated twice weekly for presence and severity of dermatitis. As shown by the results summarized in Figure 3, use of the petrolatum-containing diaper was associated with statistically significant, sustained reductions in the severity of dermatitis, compared with the control product. The accumulated results offer strong evidence that delivery of dermatological formulations via the inner liner of disposable diapers constitutes a significant technological advance towards the goal of maintaining normal, healthy skin under the diaper.
Developments in disposable wipes
It has long been held that disposable wipes can contribute to skin irritation and induction or exacerbation or diaper dermatitis. This was a particular concern when wipes contained alcohol and other irritating agents. There is only one published evaluation of the safety of disposable wipes . The authors conducted a 10-week safety-in-use comparison of four brands of disposable wipes among a cohort of 317 children age 4 to 12 months. Their findings confirmed the suitability of each of the four products for daily infant care. Comparatively, the primary difference among test wipes that they observed were changes in skin pH. Wipe brands of low pH tended to reduce skin pH somewhat, whereas those that had skin-neutral pH (5.5 approx.) had no effect on this variable. In general, though, as the authors themselves assert, these pH effects were not accompanied by changes in skin health condition.
Recent efforts have focused on evaluating the suitability of infant wipes for use on dermatitic skin. Because of ethical and logistic constraints, we have conducted this work relying on adult models of epidermal damage. A tape-stripping model has been used in which sites on the volar forearm of volunteers are tape-stripped until a stable increment in transepidermal water loss (TEWL) rates is achieved of approximately 30 g/m2/h above basal rates. On the basis of unpublished observations, this increase in TEWL rates corresponds to that observed on the skin of children who are experiencing a moderate-to-severe diaper dermatitis reaction. The time course for resolution of the associated erythematous reaction is then compared between sites that are left undisturbed after damage (control) and sites that are wiped with disposable baby wipes, four times a day for 4 days, following a regimen intended to mimic the amount of wiping a child’s skin might experience in a normal day (total daily wiping time = 135 s). In these studies, erythema scoring is done by a single trained skin grader who is blinded as to the treatment assignment of each skin site. Figure 4 summarizes the results obtained with one of our premium quality disposable baby wipes. As shown in the figure, the decline in erythema scores occurs at a relatively uniform rate during the course of the 4 days of the study at both control and wipe-treated sites. Most importantly, scores remain comparable between sites throughout the entire study and by the last evaluation on day 4, erythema resolution is nearly complete at control and test sites. Clearly, differences exist between the adult model and the situation encountered in the diaper area of a child experiencing a contact dermatitis reaction. Nonetheless, in both instances, a critical consideration is the impact of wipe application and rubbing against epidermis that is highly labile and susceptible to abrasion or frictional damage. The results thus far accumulated support the belief that high quality infant wipes are do not interfere with the normal process of skin repair.
In summary, technological advances in the development of disposable diapers have led to a better product which decreases skin overhydration and frictional damage to skin in the diaper area. The significant decrease in diaper dermatitis that has occurred in the last decade appears to correlate with the introduction of absorbent gelling materials and products designed to wick moisture away from the skin underneath diapers containing such components. Numerous toxicity and irritation studies have confirmed the safety of the new gelling products. The sparse data currently available on disposable wipes is also reassuring regarding the nonirritating characteristics of the most recently developed wipes. These and more recent advances, including the development of diapers that deliver therapeutic agents to the skin, promise to continue the trend observed in recent years toward sustained reductions in the prevalence of dermatological problems in the diaper area.
References and recommended reading
Papers of particular interest, published within the annual period of review, have been highlighted as:
• Of special interest
•• Of outstanding interest
1. Burgoon CF, Urbach F, Grover WD: Diaper dermatitis. Pediatr Clin North Am 1961, 18:835–856.
2. Leyden JJ, Katz S, Stewart R, et al.: Urinary ammonia and ammonia-producing microorganisms in infants with and without diaper dermatitis. Arch Dermatol 1997, 113:1678–1680.
3. Berg RW, Buckingham KW, Stewart RL: Etiologic factors in diaper dermatitis: the role of urine. Pediatr Dermatol 1986, 3:102–106.
4. Buckingham KW, Berg RW: Etiologic factors in diaper dermatitis: the role of feces. Pediatr Dermatol 1986, 3:107–112.
5. Campbell RL, Bartlett AV, Sarbaugh FC, et al.: Effects of diaper types on diaper dermatitis associate with diarrhea and antibiotic use in children in day care centers. Pediatr Dermatol 1988, 5:83–87.
6. Zimmerer RE, Lawson KD, Calvert CJ: The effects of wearing diapers on skin. Pediatr Dermatol 1986, 3:95–101.
7. Berg RW: Etiology and pathophysiology of diaper dermatitis. Adv Dermatol 1988, 3:75–98.
8. Berg RW: Etiologic factors in diaper dermatitis: a model for development of improved diapers. Pediatrician 1987, 14(Suppl 1):27–33.
9. Van R, Wun CC, Morrow AL, et al.: The effect of diaper type and overclothing on fecal contamination in day care centers. JAMA 1991, 265:1840–1844.
10. Kubial M, Kressner B, Raynor W, et al.: Comparison of stool containment in cloth and single-use diapers using a simulated infant feces. Pediatrics 1993, 91:632–636.
11. Van R, Morrow AL, Reves RR, et al.: Environmental contamination in child daycare centers. Am J Epidemiol 1991, 133:460–470.
12. Campbell RL: Clinical tests with improved disposable diapers. Pediatrician 1987, 14(Suppl 1):34–38.
13. Campbell RL, Seymour JL, Stone LC, et al.: Clinical studies with disposable diapers containing absorbent gelling materials: evaluation of effects on infant skin condition. J Am Acad Dermatol 1987, 17:978–987.
14. Lane AT, Rehder PA, Helm K: Evaluations of diapers containing absorbent gelling material with conventional disposable diapers in newborn infants. Am J Dis Child 1990, 144:315–318.
15. de Prost Y: Results of an efficacy clinical diaper study with superabsorbent panty diaper conducted in French day care centers. In Diaper Dermatitis: Later Insight Into Pathogenesis, Prophylaxis, and Therapy. Edited by Tronnier H, Schmitt GJ. Munich, Germany: Verlag Medical Concepts; 1987:111–114.
16. Oranje AP, Bilo AC, de Waard-vd S, et al.: Dutch clinical diaper study. In Diaper Dermatitis: Later Insight Into Pathogenesis, Prophylaxis, and Therapy. Edited by Tronnier H, Schmitt GJ. Munich, Germany: Verlag Medical Concepts; 1987:115–122.
17. Tronnier H: Tolerance and efficacy characteristics of panty diapers with highly absorbent pad. In Later Insight Into Pathogenesis, Prohylaxis and Therapy. Edited by Tronnier H, Schmitt GJ. Munich, Germany: Verlag Medical Concepts; 1987:123–126.
18. Spraker M, Krafchik B, Leyden J, et al.: Disposable diapers: effective and safe. Contemp Pediatr Suppl 2000:4–18.
19. Reference deleted by author.
20. Wigger-Alberti W, Elsner P: Petrolatum prevents irritation in an human cumulative exposure model in vivo. Dermatology 1997, 194:247–250.
21. Zhai H, Maibach HI: Effect of barrier creams: human skin in vivo. Contact Dermatitis 1996, 35:92–96.
22. Ghadially R, Halaker-Sorensen L, Elias PM: Effects of petrolatum on stratum corneum structure and function. J Am Acad Dermatol 1992, 26:387–396.
23. •• Odio MR, O’Connor RJ, Sarbaugh S, et al.: Continuous topical administration of a petroleum formulation by a novel disposable diaper: I: effect on skin surface microtopography. Dermatology 2000, 200:232–237. This series of two related articles (see also Ref. 24) describes a novel strategy being pursued to further improve the condition of skin under the diaper, namely, the addition of dermatological formulations intended for topical delivery during product use. The articles confirm the viability of using the inner liner of the diaper as a vehicle for formulation delivery as well as the benefits of this approach in terms of reduced irritation and frequency and severity of diaper dermititis.
24. Odio MR, O’Connor RJ, Sarbaugh S, et al.: Continuous topical administration of a petrolatum formulation by a novel disposable diaper: II: effect on skin condition. Dermatology 2000, 200:238–243.
25. Priestly GC, McVittie E, Aldridge RD: Changes in skin pH after the use of baby wipes. Ped Dermatol 1996, 13:14–17.
Edited by Lawrence F Eichenfield and Sheila Fallon Friedlander