A plasticiser is a substance which when added to a material,
usually a plastic, produces a product which is flexible, resilient
and easier to handle. Since the dawn of civilisation, water has
been used to plasticise clay for the production of pottery and clay
tablets. Also, lime has been used to promote the easier working of
cements. Other early examples of plasticisers include the oils to
plasticise pitch for caulking prehistoric boats and neatsfoot oil
and sperm oil to soften leather. In modern applications
plasticisers must satisfy more demanding technical and economic
requirements. These requirements are best met by esters such as
phthalates, adipates and trimellitates. Phthalates, due to their
technical performance, versatility and cost effectiveness, are the
most widely used plasticisers.
There is no truth in this story whatsoever. The authors have
confused two chemicals, neither of which are used in the
manufacture of plastic bottles.
The story that has been circulating refers to diethyl
hydroxylamine (or DEHA) leaching out of the plastic on repeated
washing and rinsing. It warns people to discard such bottles after
a single use and not to refill them.
Diethyl hydroxylamine is indeed sometimes abbreviated as DEHA
but it has nothing to do with plastic water bottles. The author of
this story is probably confusing it with diethylhexyl
adipate (also abbreviated as DEHA) which is an approved
plasticiser often used to make plastics soft and pliable (more information on diethylhexyl adipate).
However, this is also not used to make plastic
water bottles which are most commonly made from polyethylene
terephthalate (PET).
Neither DEHA is classified as a carcinogen.
In an article published in the Montreal Gazette in November
2003, Joe Schwarcz, director of McGill University's Office for
Science and Society, explained where he believes the rumours may
have started from.
"As with many such Internet scares, there is a kernel of truth.
In this case, it is found in an abstract of a talk given by a
master's student from Idaho at a scientific conference. Such
abstracts are not subject to peer review and are not considered a
form of scientific publication. The intent is the information will
be submitted to a journal, where it will undergo review by experts.
As far as I can tell, that never happened, probably because the
study did not have the scientific rigour required.
"The student investigated contaminants in bottled water and
found a number of organic compounds, including diethylhexyladipate.
"Apparently unaware this is not used in polyester bottles, the
author assumed it was leaching out of the plastic. The student
examined a variety of other plastic bottles and found DEHA in the
water they contained, leading to the conclusion "migration of DEHA
was not limited to polyester bottles alone and other bottles may
also pose a health hazard." But a critical control experiment was
never done.
"Was there DEHA in water stored in glass bottles or in water
from the tap? Actually, there is. Because DEHA is a ubiquitous
plasticizer used in the manufacture of items ranging from toys to
shower curtains, it shows up in trace amounts everywhere. Water
samples that had never been in contact with a plastic bottle showed
traces of DEHA!
"Whether the samples came from plastic or glass bottles, they
contained the inconsequential amount of about 0.01 to 0.05 parts
per billion. The World Health Organization has set a maximum of 80
ppb for DEHA in drinking water so there is no issue with plastic
bottles. At least not as far as DEHA goes.
"There may be reasons not to refill water bottles, but that has
to do with possible bacterial contamination."
