Are we falling for aniline, hook, line and sinker?
by James Carnahan, Head of Sustainability,
I can recall, in the late 1980s, the big
debate within the textile manufacturing industry regarding the
presence of formaldehyde on textiles.
In 1980, laboratory studies had shown that
exposure to formaldehyde could cause nasal cancer in rats,
questions were raised whether exposure could cause cancer in
humans and further studies were made.
As a result, in 1987, the U.S.
Environmental Protection Agency classified formaldehyde as a
probable human carcinogen under conditions of unusually high or
prolonged exposure. Test methods were devised, and the confusion
started as the test methods tested for different
"availabilities" of formaldehyde and gave significantly
To the scientist they were easy to
understand, to the other decision makers in the textile value
chain? Maybe a bit more complicated. Limits on textiles were
soon to follow and heated debates could be heard at textiles
symposia regarding whether formaldehyde was a risk at all, as it
was ubiquitous in nature and natural levels of formaldehyde in
apples were higher than the limits being imposed on textiles.
The major multinational textile chemical
manufacturers developed alternative, "low formaldehyde" and
"formaldehyde free" chemistries. The latter were not really
taken up by the industry in appreciable volumes as they were
more expensive alternatives, and the new "low formaldehyde"
variants could be "washed" to achieve the limits... sometimes.
Fast forward to 2014, and the United
Nations Global Harmonized System for Classification and Labeling
of Chemicals (GHS) classifies formaldehyde as a category 1B
carcinogen, previous to this it had been classified as a
category 2 carcinogen.
Now we see sales of these "formaldehyde
free" alternatives increasing. Surely, formaldehyde was always
hazardous. It seems that the precautionary principle was not
So what about
Aniline has been used as a precursor in
the synthesis of dyes since the late 1800s, BASF (Badische
Anilin und Soda Fabrik) was responsible for the first commercial
synthesis of indigo in 1897 using aniline as one of the starting
blocks. Aniline is also used for the synthesis of other dyes.
In the last few years we have seen
contamination levels of aniline in indigo rising. We also know
that for indigo in the denim manufacturing process, the amounts
of aniline remaining on the fabric are often disproportionate to
the amount of aniline entering the manufacturing system.
So where is it
We realized that a large proportion was
exiting the manufacturing chain in wastewater from textile
mills, and we could not be certain that effective effluent
treatment was in place in all textile manufacturing sites to
deal with the aniline before entering watercourses.
This, coupled with the fact that it is a
category 1 acute aquatic hazard, indicated that a hazardous risk
to the environment was present.
Although aniline is "only" a category 2
carcinogen (remember formaldehyde?) the industry in general does
not consider aniline as a risk from a consumer safety
perspective. Exposure levels at the garment stage, especially
those having undergone garment-washing processes, were low.
But interestingly, we have seen that
aniline has started to appear on restricted substance lists,
which would indicate that there is uncertainty over the
substance and the risk it may pose to the consumer.
However, the same risk certainly applies
to the workers involved in the various manufacturing stages,
often operating in regions where occupational health and safety
legislation was not commonly observed to be in practice, where
exposure levels are significantly higher than those of the
We decided to go into R&D to investigate
whether we could bring a pre-reduced indigo to the market with
markedly reduced amounts of aniline contamination. After almost
2 years we were able to find a solution. Yes, it would mean a
more expensive manufacturing process for us, but not "ramp up
costs" to those of pharmaceutical grade chemical levels.
We decided to take the precautionary
principle approach, because if we could offer a solution where
aniline was not present - and here we mean below the levels of
detection according to industry standard test methods - then
this would provide the opportunity, for concerned denim
manufacturers and brands, to take the uncertainty out of the
equation, surely a better way than maintaining the status quo?
Since the launch of Denisol® Indigo Pure,
we have seen a rise in demand, and thus it seems that common
sense has prevailed. At the same time, we acknowledge that at
the moment we cannot produce enough to replace all the current
indigo required by the market, but this should not deter us from
moving forward and allow those enlightened textile mills and
brands to make desirable, rather than regrettable,
nature, after all.