46 | New Scientist | 29 January 2022
what we could do 15 years ago.”
Meanwhile, other projects are looking
in a concerted way at how the things we are
exposed to affect our health. Many studies
focus on “barrier organs”, such as the skin,
lungs and gut, which are well-adapted to deal
with environmental assaults. Others concern
internal organs and systems, such as the lungs,
liver and gut and the cardiovascular, immune
and metabolic systems. These studies confirm
what has long been suspected: the barrier
organs are routinely breached, and our bodies
flooded full of chemicals. “Even though some
exposures may only be detected at the barrier
organ, the impact goes far beyond, say
changing our metabolic function,” says Peters.
As just one example of many, at a conference
held by EHEN in 2021, Doug Walker at the Icahn
School of Medicine at Mount Sinai in New York
reported how his team has linked various
chemical exposures to a liver disease called
primary sclerosing cholangitis, which was
previously of unknown origin. The research
also confirmed a long-standing hypothesis
that exposure to benzene – an intermediate in
the manufacture of many industrial chemicals
and a by-product of burning fossil fuels – can
cause leukaemia.On top of that, people in the same place
may not receive the same insults. “Two people
in the same room can have very different
exposures depending on where they are
sitting,” says Snyder.
Woychik worries that such complexities
could be the undoing of exposomics, a fatal
flaw that prevents it becoming environmental
health science’s answer to the Human Genome
Project. At the moment, it risks becoming
“everything about everything about
everything”, says Woychik. “I believe we need
to do a better job of defining precisely what
it [exposomics] is.” To be truly worthy of
becoming a new -omics, it needs to follow the
footsteps of genomics and produce a joined-up
understanding of all of the environmental
exposures that are out there and how they
influence our biology, says Gary Miller at
Columbia University in New York, the editor
of a new scientific journal called Exposome.
These are serious challenges, but researchers
are increasingly confident of rising to them.
Last year, Peters and her colleagues Andrea
Baccarelli at Columbia University and Tim
Nawrot at Hasselt University in Belgium
published what they hope will become a
landmark paper. Its title, “Hallmarks ofIn the paper “Hallmarks of environmental
insults” published last year, researchers
set out eight distinct ways in which
the things we are exposed to in our
environments can have effects on
our health.- OXIDATIVE STRESS
AND INFLAMMATION
Many environmental pollutants contain
extremely aggressive chemicals called
reactive oxygen species. These can
overwhelm our natural antioxidant
defences and cause inflammation,
cell death and organ damage. - GENOMIC ALTERATIONS
AND MUTATIONS
Mutagens in pollutants damage DNA and
trigger cancer and other chronic diseases. - EPIGENETIC ALTERATIONS
Air pollution, pesticides and heavy metals
have been shown to induce harmful
changes in gene expression during our
lifetimes through effects such as DNA
methylation and histone modification,
which are known to be linked to the
process of ageing.- MITOCHONDRIAL DYSFUNCTION
Mutagens and reactive oxygen species
can also damage the genome and
epigenome of mitochondria, our
cells’ power packs. Such damage
seems to increase the risk of
conditions such as type 2 diabetes
and breast cancer. - ENDOCRINE DISRUPTION
Many chemicals found in the
environment, food and consumer
products disrupt the regulation of
hormones, something that might be
associated with type 2 diabetes and
age-related thyroid dysfunction.
6. ALTERED CELL COMMUNICATION
Some pollutants directly interfere
with cell-to-cell communication, and
prematurely aged cells can become
dysfunctional communicators.
The result can be “inflammaging”,
or system-wide chronic inflammation
that is a hallmark of ageing.
7. ALTERED MICROBIOME COMMUNITIES
Toxic environmental substances
reaching the gut can alter its microbial
communities, increasing susceptibility
to allergies and infections.
8. IMPAIRED NERVOUS SYSTEM
FUNCTION
Noise pollution can disrupt the autonomic
nervous system, leading to hikes in blood
pressure and cardiovascular disease.
Microscopic particles in air pollution
reach the brain through the olfactory
nerve and interfere with cognition.
Eight ways the environment affects our bodies
And if we want to truly understand the
impact of the environment on our health as
individuals, we need to get to grips with the
enormous variation in our ability to deal with
toxic substances. These differences are mostly
down to the genes we inherit from our parents,
but can also be epigenetic, caused by changes
to our genetic make-up as a result of events
through our lives. Experiments in mice suggest
that the speed with which benzene is cleared
from the bloodstream varies between
individuals by as much as a factor of 10. “This
is probably true for most toxicities,” says Rick
Woychik, the director of NIEHS. “An exposure
that may be dangerous and detrimental to one
individual may not apply to someone else.”“ We need to get to grips
with an enormous
variation in our ability
to deal with toxic
substances in our
environment”