Babies use diapers until approximately age 3, and the Boston Children's Hospital estimates that translates into between 2,000 and 3,000 annual diaper changes for every child. Nobody knows the exact number of disposable diapers used every year, but the Oregon State University College of Engineering estimated in 2004 that 20 billion diapers went into landfills. Parents and community members both have an interest in identifying the materials used to make disposable diapers for correct use and safe disposal.
Disposable diapers have an exterior that incorporates a plastic-covered fabric called PUL to keep moisture from seeping out of the knitted interior lining of cotton, bamboo or synthetics. Polyurethane-laminated fabric has a thin coat of plastic attached to a fiber-and-paper mix to make the exterior waterproof. Manufacturers attach small Velcro straps, self-attaching synthetic fabric, or plastic adhesive to secure the back of the diaper to the front. Many diapers add thin elastic strings or woven plastic fibers around each diaper leg to tighten the opening to reduce the chance for leaks.
The interior cotton and paper fabric used in disposable diapers embeds sodium polyacrylate crystals, a type of super-absorbent polymer that holds up to 300 times the material weight in liquid, between layers. The fabric partially absorbs the moisture and uses SAP to store the rest of the liquid as a gel in the bottom of the diaper.
Disposables have chemical traces from the manufacturing process and chemical additives to create a pleasant fragrance. Early studies of disposables done by the Anderson Laboratories in 1999 link processing to asthma-like respiratory symptoms in babies, including runny noses, sore throats and eye irritation. Diaper companies use bleach on recycled paper and fibers, and also add deodorant to scent the diapers. Studies found trace amounts of dioxin, a byproduct of the bleaching process, in the disposables, according to GreenAmerica.org. The Environmental Protection Agency links dioxin with cancer in laboratory tests. Other chemicals found in disposables include xylene, ethylbenzene, styrene and ispropylene, all chemicals related to petrochemicals. The high-tech chemical compounds create diapers with increased durability compared with other paper and fabric materials.
Biodegradable diapers use some of the same fabric components as disposable diapers, but also use patented biodegradable and compostable biopolymers made with renewal materials. Patented non-woven fabrics feature polylactic acid, a product made from plants. Diapers use the materials to make the diaper leg cuffs and the top and back sheet of the main body of the disposables.