Otago scientist in international task force linking chemical mixtures
in the environment to cancer
Strictly embargoed until 4.05pm Tuesday 23 June 2015
Mixtures of common chemicals used in our environment may act in concert with each other
in the human body to cause the development of cancer. This is the overall finding of groundbreaking new research by an international task force that included New Zealand.
Dr Linda Gulliver, from the University of Otago’s Faculty of Medicine, was the only New
Zealand scientist selected to join an ‘Environmental Mixtures’ task force, one of two task
forces assembled by an NGO called “Getting to Know Cancer” in Halifax Nova Scotia in July
2013.
Amid worldwide concern on high rates of cancer, the task force brought together 174
scientists from prominent institutions in 28 countries to tackle longstanding concerns that
there are linkages between mixtures of commonly encountered chemicals and the
development of cancer.
From the thousands of chemicals to which the population is now routinely exposed, the
scientists selected 85 prototypic chemicals that were not considered to be carcinogenic to
humans, and they reviewed their effects against a long list of mechanisms that are important
for cancer development.
Working in teams that focused on various hallmarks (shared characteristics) of cancer, the
group found that 50 of those chemicals examined supported key cancer-related mechanisms at
environmentally relevant levels of exposure (i.e. levels at which humans are routinely
exposed).
This supports the idea that chemicals may be capable of acting in concert with one another to
cause cancer, even though low-level exposures to these chemicals individually might not be
carcinogenic.
“Since so many chemicals that are unavoidable in the environment can produce low-dose
effects that are directly related to carcinogenesis, the way we've been testing chemicals (one
at a time) is really quite out of date. Every day we are exposed to an environmental 'chemical
soup', so we need testing that evaluates the effects of our ongoing exposure to these chemical
mixtures,” says William Goodson III, a senior scientist at the California Pacific Medical
Center in San Francisco.
Goodson is the lead author of this synthesis of the findings, which is today published (along
with a seminal series of supporting reviews authored by each of the teams) in a special issue
of the top-tier journal Carcinogenesis.
Their published report says: “Cumulative risk assessment methods that are based on ‘common
mechanisms of toxicity’ or common ‘modes of action’ may be underestimating cancer-related
risks….
“And current regulations in many countries (that consider only the cumulative effects of
exposures to individual carcinogens that act via a common sequence of key events and
processes on a common target/tissue to produce cancer) should be revisited.”
In light of this evidence, the task force is calling for an increased emphasis and support for
research on low-dose exposures to mixtures of environmental chemicals.
This was the first time this large-scale problem has ever been considered by interdisciplinary
teams that could fully interpret the full spectrum of cancer biology and incorporate what is
now known about low-dose chemical effects.
Dr Linda Gulliver is a senior lecturer and reproductive biologist with an interest in oestrogenrelated cancer causation. She was recruited into the “The Halifax Project” initiative in late
December 2012.
Dr Gulliver was a member of the ‘Sustained Proliferative Signalling’ team, which looked at
one of the ten established hallmarks of cancer cells; their ability to grow and multiply in an
uncontrolled manner that is prevented in normally functioning cells.
She says her own team found that chemicals that act as environmental oestrogens and
androgens play important roles in the activation of the cancer hallmark of “Sustained
Proliferative Signalling,” as well as the cross-activation of several of the other cancer
hallmarks.
And Dr Gulliver agrees with her colleague Dr David Carpenter, project contributor and
Director of the Institute for Health and the Environment of the University at Albany in New
York, that research into the area of how low-dose mixtures of environmental chemicals may
facilitate cancer causation “merits considerable attention where interdisciplinary and
international collaboration is needed.”
Dr. Carpenter adds: “The science in this field is changing rapidly. Although we know a lot
about the individual effects of chemicals, we know very little about the combined and
additive effects of the many chemicals that we encounter every day in the air, in our water
and in our food.”
Current estimates suggest that as many as one in five cancers may be due to chemical
exposures in the environment that are not related to personal lifestyle choices. So the effects
of exposures to mixtures of commonly encountered chemicals needs to be better understood
to try and reduce the incidence of cancer.
Contact:
Dr. Linda Gulliver
Faculty of Medicine
University of Otago
Tel 64 3 470 4689
Mob 64 21 149 9047
linda.gulliver@otago.ac.nz