29 January 2022 | New Scientist |
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exposures risks ignoring a healthier side of the
exposome. “What are we missing? The good
stuff,” he says. “We always think of exposures
as bad, but there are probably a lot of good
health compounds out there. That’s a whole
blank area.” He speculates, for example, that
chemicals given out by natural environments,
for example by trees in forests, might account
for some of the health benefits we seem to
accrue by being in such environments.
Working out longer-term exposure effects
is something else that needs work and time.
“Long-term effects is one of the hardest
problems out there,” says Snyder. “But that is
no reason not to start now. We should start
studies now that will give us data 30 years from
now, 50 years from now, so that at least our
grandkids will get some benefit out of that.”
If we want to halt the pandemic of chronic
disease and premature ageing, then we can’t
start soon enough. “There is so much health
to gain and well-being to gain,” says Vrijheid.
“If we are serious, this will change our lives.”
❚
overcoming the challenge we currently have
with pollution,” she says.
Not only that, but as Martine Vrijheid at the
Barcelona Institute for Global Health in Spain
points out, many of the things we can do to
minimise our exposure to harmful pollutants
– reduce air pollution, switch to healthier diets
and choose active transportation such as
walking and cycling – intersect with actions
that can help the climate.
For many of us, minimising our exposure to
environmental pollutants is easier said than
done – and we aren’t far enough down the line
of teasing out the interplays between exposure
and genetics to make recommendations
beyond that. “It would be hard to say that,
based on this risk factor, you shouldn’t do
this,” says Snyder. But signs of actionable
results are starting to emerge, he adds:
we now know, for example, that certain
combinations of genes increase the risk of
pesticide exposure leading to Parkinson’s.
Even with the hallmarks framework in place,
there are still knowledge gaps. Peters and her
co-authors considered adding stem cell
dysfunction to their list, but didn’t have quite
enough evidence to do so. Other hallmarks
may well emerge, says Peters. Snyder also
points out that the relentless focus on harmful
Graham Lawton is a feature writer at
New Scientist and author of
Mustn’t
Grumble: The surprising science of
everyday ailments
environmental insults”, is a knowing nod to
two earlier ones that have had a transformative
impact. “The hallmarks of cancer” (2000) and
“The hallmarks of aging” (2013) both took big,
seemingly intractable biological problems and
boiled them down to underlying principles.
The ageing paper, for example, takes the fuzzy
idea that ageing is a general breakdown of
biological function and re-conceptualises it
as the accumulation of nine different classes of
cellular or molecular damage, many of which
are now targets for medical intervention.
It has been cited more than 7000 times.
In the new paper, Peters and her co-authors
break down the ways in which environmental
insults affect the human body, from oxidative
stress and inflammation to impaired nervous
system function (see “Eight ways the
environment affects our bodies”, below left).
The hope is that doing this could help develop
and focus prevention strategies and
treatments. “Every day we learn more about
how exposure to pollutants in air, water, soil
and food is harmful to human health,” says
Baccarelli. “Less understood, however, are the
specific biological pathways through which
these chemicals inflict damage on our bodies.”
It also begins to explain why some types
of exposure are so damaging. For example,
persistent exposure to air pollution, which has
been identified as the direct cause of about
4 million preventable deaths worldwide every
year, hits all eight hallmarks. Observational
studies show that fine particulates smaller
than 2.5 micrometres across are particularly
problematic for our health.
Another insight is the overlap between the
hallmarks of exposure and those of ageing.
Four of the eight – genomic alterations and
mutations, epigenetic alterations,
mitochondrial dysfunction and altered
intracellular communication – are hallmarks
of ageing. Another, oxidative stress and
inflammation, is a known cause of diseases
that hit us more as we grow older: things like
dementia, cancer, diabetes, heart and
respiratory conditions, Parkinson’s disease
and osteoarthritis. Exposure to environmental
insults is literally causing us to age more
rapidly, says Peters. “As our bodies age, we
accumulate changes at various sites. For
environmental exposures, it’s the same thing.”
The primary focus of exposomics is
improving human health, but it could have
a positive effect on planetary health generally,
too. Plants and non-human animals respond
to environmental insults in a similar way to
humans, says Peters. “So this underlying
framework can be a major contribution to
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