On October 20, 2011, the Siloxane D5 Board of Review
("Board") released a report3 concluding that
decamethylcyclopentasiloxane (D5), an odorless, colorless compound
used in a variety of dry-cleaning, personal care and cosmetic
products, did not pose a danger to the environment or its
biodiversity. This report generated interest not only because it
disagreed with Environment Canada's risk analysis and
conclusions with respect to D5, but because it was the first ever
report from a board of this kind.
In 2008, Environment Canada and Health Canada conducted a
screening assessment of D5 under the Canadian Environmental
Protection Act, 1999 (CEPA) which concluded that D5 was being
released into the environment in a quantity or concentration, or
under conditions, that may have an immediate or long-term harmful
effect on the environment or its biological diversity. The
conclusion relied heavily on the finding that D5 exceeded the
regulatory thresholds for "persistence"1 and
As a result, D5 was identified as a chemical to be added to
Schedule 1, the List of Toxic Substances, under CEPA. If that step
were taken, it would have required the government to institute
regulatory measures to mitigate or eliminate the risk, potentially
leading to, among other options, a complete ban on the use of the
Under CEPA anyone wishing to challenge a decision to list a
compound as toxic may file a Notice of Objection and request that a
board of review be convoked to reconsider the issue.
The Silicones Environmental, Health and Safety Council of North
America ("SEHSC") filed such a notice respecting D5 on
July 14, 2009, and for the first time in the eleven-year history of
CEPA the Minister of the Environment agreed, establishing the
Siloxane D5 Board of Review.
The Board, made up of three internationally renowned
toxicologists, received submissions from Environment Canada, the
SEHSC and two intervenors.3 It conducted a de novo risk
assessment to determine the nature and extent of the danger posed
by D5 to the environment or its biological diversity. After
assessing the submissions, all available scientific information
respecting D5 (including new information that was not available to
Environment Canada in 2008) and evidence from witnesses across the
globe over a two-week hearing, the Board concluded that D5 does not
pose such a risk. BLG was counsel to the three scientists
conducting the review.
The Board concluded that the screening assessment conducted by
government officials in 2008 was flawed, that it used
overly-conservative modeling and that it inaccurately characterized
the compound's fate in the environment. Further, the Board
found that Environment Canada failed to take into account the
intrinsic properties of D5 in reaching its conclusions with respect
to the persistence and bioaccumulation of the compound.
Furthermore, the Board concluded that, because the compound has
likely reached a "quasi-steady-state" within the
environment, D5 will not likely pose a danger to the environment or
its biodiversity in the foreseeable future.
The Board's Report contained a number of recommendations.
These included a recommendation that Environment Canada regularly
update its regulations establishing bioaccumulation and persistence
thresholds to reflect the current state of the science, and to
ensure that risk assessments and models used in screening
assessments are accurate, up to date, understandable and
transparent. The Board also urged industry to work with government
agencies "to fill data gaps and provide relevant commentary
Clients may wish to consider invoking a board of review in the
future. The Board process in this case, adopted with BLG's
assistance, was the first of its kind and will likely guide both
government and industry in respect of any future screening
assessments of potentially toxic chemicals and boards of review
that the Minister may choose to convoke.
1 The persistence of a chemical is an estimate of how
long it will remain in the environment or an organism.
2 The process by which chemicals accumulate in organisms
from the medium surrounding the organisms, including sources such
3 The Canadian Cosmetic, Toiletry and Fragrance
Association and the Coalition consisting of the Canadian
Environmental Law Association, The International Institute of
Concern for Public Health, Chemical Sensitivities Manitoba and the
Crooked Creek Conservancy Society of Athabasca were both granted
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