Fire Safety and Technology Editorial
Flammable Diapers
Note that not all flammability litigation is equally valid.
A TV station in Washington State has just posted a story about the flammability of adult diapers. It is likely to involve litigation claims. The claim, from a fire investigator, is that disposable diapers "proved to be very flammable," and that "the material dripped with the same consistency of plastic."
The claim continues, by stating that the "intensity
of the flames was due to the flammability of the adult diaper"
"along with [the victim's] synthetic clothing." Moreover,
the fire investigator called to the scene says the "drops of fire"
that fell from the victim's clothing were from the disposable adult
undergarment which, along with the victim's other clothing, had caught
fire and burned.
The investigator further states,: "I knew plastic
was going to do this…" "…just never thought about
the diapers" and "The undergarment is made of petroleum product.
It is a man-made synthetic material that burns with the heat and intensity
of flame. Take a pint of gasoline and strap it to you in a solid state.
That's what it is."
In order to understand the issue it is interesting to
think what disposable diapers are and what they are made of. Disposable
diapers consist of an absorbent pad sandwiched between two sheets of
nonwoven fabric. The pad is designed to absorb and retain body fluids,
and the nonwoven gives the diaper a comfortable shape and helps prevent
leakage.
The absorbent pad is attached to a permeable top sheet
and an impermeable bottom sheet, and all components are sealed together
(usually by heat). Elastic fibers are attached to the sheets to gather
the edges of the diaper into the proper shape so it fits snugly around
legs and crotch. When properly fitted, the disposable diaper will retain
body fluids which pass through the permeable top sheet and are absorbed
into the pad.
Early disposable diapers used wood pulp fluff, cellulose wadding, fluff
cellulose, or cotton fibers as the absorbent material, but these materials
did not absorb enough moisture per unit weight, resulting in bulky diapers.
Today's disposable diapers absorb 15 times their weight in water.
This absorption rate is due to the pad materials: a hydrophilic
polymer (i.e. one that absorbs water) and a fibrous cellulosic material,
such as wood pulp. The hydrophilic polymer is usually some type of an
acrylate (which is a thermoplastic) that has been designed with hydrophilic
portions (those that absorb water) and portions intended to become cross-linked
so that a gel is formed that retains the absorbed moisture. Nonwovens
are typically made from thermoplastics, such as nylon, polyester, polyethylene,
or polypropylene.
In summary, disposable diapers are mostly made of specially-designed
thermoplastic materials, because such materials are efficient in performing
the function of the diaper: absorbing large amounts of watery liquids,
while remaining relatively unobtrusive, especially when used by adults.
When thermoplastics are heated they will melt and drip.
If thermoplastics are exposed to open flame, in many cases they will
result in flaming drips. However, it is essential to consider that diapers
are intended to be filled with watery liquids and are intended to be
worn as clothing under other items of wearing apparel. Thus, the probability
of dry diapers coming into contact with open flames is very low, unless
the apparel itself is already burning.
Since 1953, wearing apparel in the US has had to meet
a fire test, now regulated as 16 CFR 1610 (originally CS-191-53 and
very similar to the test in ASTM D 1230, Standard Test Method for Flammability
of Apparel Textiles). This test was enacted by the US Congress and is
currently administered by the US Consumer Product Safety Commission
[CPSC].
In the test, samples tested are placed in a sample holder
at a 45º angle, and the igniter flame is imposed on the upper surface
of the sample. The test requires that samples of fabrics used in clothing
apparel comply with one of the following criteria: (a) no ignition when
subjected to a small gas diffusion flame emitted from a burner based
on a hypodermic needle during an exposure of 1.0 s, or (b) if the fabric
sample ignites, the flames shall not spread 5 inches [127 mm] in less
than 3.5 seconds. The regulation addresses the sensitivity of this test
method to fabric weight by providing that fabrics with areal densities
> 2.6 oz/yd2 [roughly 60 g/m2] be excluded from testing, as they
are considered too heavy to ignite under the test conditions.
However, US regulation does not require that apparel be
made without fabrics that ignite whenever a flame is applied to them,
nor should it. In fact, clothing rarely ignites while it is worn: in
the US there were an average of 520 fires ignited on clothing worn by
a person over the period 1999-2002, and such fires have been decreasing
in recent years.
However, when fires do occur while clothing is worn by
an individual, the results can be catastrophic! The apparel fires above
resulted in 120 yearly fire fatalities and 149 fire injuries, with a
ratio of fires to fire fatalities of 4.3, a ratio that is much worse
than the ratio for other textile consumer products frequently involved
in fires such as upholstered furniture (17.7), mattresses (42.3), floor
coverings (69.7), curtains and drapes (153.5) or clothing not on a person
(161.5). All these other items are much more likely to be involved in
fires than clothing fabrics.
A recent study showed clearly that, as areal density (weight)
of fabrics increase, their fire performance becomes better. The most
important consequence of this observation is that better fire performance
in heavier fabrics is largely, but not completely, independent of fabric
composition. However, no one should be forced into wearing only heavyweight
fabrics.
Therefore, it is my opinion that the flammability of adult diapers should be a non issue unless they are being worn without being covered by combustible clothing and/or by people with careless use of open flame sources near their bodies.
Marcelo M. Hirschler
