15/01/2005 Most people find
washing dishes at home a chore, but new evidence
has shown that it could have other more unpleasant
effects.
Scientific research carried out in the United
States have found that when dishwashing liquid
containing triclosan, an anti-bacterial agent,
was mixed with chlorinated tap water it produced
significant quantities of chloroform* .
Chloroform has been classed as a probable
human carcinogen by the US Environmental Protection
Agency, and according to the scientists at
Virginia Polytechnic, USA, who carried out
the research, "The presence of trihalomethanes
such as chloroform in drinking water has been
linked with human bladder cancers and miscarriages".
Triclosan has been on the market for more
than 30 years, used as an anti-bacterial agent
in cosmetics, personal care products (toothpastes,
acne creams, deodorants, lotions) and hand
and dishwashing soaps. It is also incorporated
into a wide range of plastic consumer goods,
including kitchenware and chopping boards.
Its popularity stems from the fact that it
stays on skin or surfaces, providing long-lasting
action against germs.
Unfortunately, it also stays in the human
body and the environment. Triclosan is bioaccumulative
and it has been found in human breast milk,
and one of its variations, Methyltriclosan
(formed by the biodegradation of triclosan
in sewage treatment works), has also been
accumulating in fish from Swiss Lakes.
While researchers had known that chlorine
could react with compounds like triclosan
to produce chloroform, noone had proved until
now that this could happen in a domestic setting.
By mimicking the conditions under which dishes
would be washed at home – such as water temperature
and concentration of chlorine -, it was found
that chloroform could be produced and absorbed
through the skin or inhaled.
It also appears that people who use moisturisers
or children who have used antimicrobial soap
containing triclosan who go swimming could
also be a potential source of chloroform and
other dioxins. As Peter Vikesland, one of
the scientists at Virginia Polytechnic pointed
out, "If someone who has a moisturiser
containing triclosan jumps into the swimming
pool….they’re a potential source for chloroform
and chlorinated dioxin formation".
Triclosan finding its way into rivers
However it is not just in domestic use that
triclosan is potentially harmful. Scientists
from the University of Minnesota** recently
demonstrated that triclosan in river water
can be converted by sunlight into dioxins.
This means that domestic products containing
triclosan that are flushed down domestic drains
into rivers could be converted into potentially
harmful dioxins. Because this water eventually
finds its way into wastewater treatment plants
scientists are calling for more research to
see whether these plants are releasing dioxins.
Dioxins are persistent and bioaccumulative
chemicals, meaning they do not degrade over
time, and can be accumulated in body tissues.
Therefore even low-level inputs in to the
environment can contribute to increasing concentrations
further up the food chain.
REACH doesn’t go far enough in treating mixtures
This recent research reveals the unintended
result of mixing triclosan with chlorinated
water and clearly demonstrates why WWF would
like all available data on everyday chemicals
to be provided through REACH.
Mixtures of a different kind are the focus
of another piece of interesting research from
the United States which highlights the kinds
of challenges presently facing toxicologists
and some shortcomings of the proposed EU chemicals
legislation, REACH.
Research from the Harvard School of Public
Health demonstrated that when two chemicals
– PCBs and phthalates - interact they affect
the human sperm’s ability to fertilise eggs
properly. As the HSPH researchers say, "an
understanding of how chemical classes interact
is essential to determining risk because humans
are concurrently exposed to numerous classes
of chemicals".
This research has ramifications for the scope
of REACH and chemical control in the European
Union. While chemical companies had complained
that REACH was too broad a proposal, it now
appears that in some respects it does not
go far enough. REACH as envisaged will evaluate
the potential harm of individual chemicals
but it does not stipulate that mixtures of
chemicals should be tested.
This new research demonstrates that while
individual chemicals could be tolerated in
small amounts, when they interact with others
they might have more serious consequences.
By omitting the possibility of evaluating
chemical mixtures, the legislation leaves
the door open for considerable sources of
chemical risk for wildlife and humans.
* Formation of chloroform and chlorinated
organics by free-chlorine mediated oxidation
of triclosan. Krista L.Rule, Virginia R.Ebbett
and Peter Vikesland, Envir.Sci.Technology;
2005
** Kristopher McNeill and William Arnold,
Envir.Toxicol.Chem. 2005, 24, 517-525
