44 | New Scientist | 29 January 2022
Features
Our world
against us
The environment is making us sick – but exactly how is
devilishly complex to understand, says Graham Lawton
M
ICHAEL SNYDER wears four
watches, two on each wrist. A
geneticist at Stanford University,
California, he isn’t obsessed with time – only
with buying us all a little more of it. The
watches track his movements and vital signs
such as heart rate and body temperature. He
also carries round a walkie-talkie-sized device
to sample everything airborne he comes into
contact with, from chemicals to viruses.
Snyder is trying to help answer an age-old
conundrum: how does our environment affect
our health? Every time we breathe, eat, drink,
wash, exercise, get dressed, go to work or climb
into bed, we expose ourselves to potentially
harmful substances – air pollution, synthetic
chemicals, contaminated food and water,
radiation, pharmaceuticals, alcohol, noise
and microorganisms, to name but a few.
Every year, between 9 and 12 million people
die prematurely through the cumulative effect
of such exposures, mainly air and water
pollution, heavy metals, synthetic chemicals
and workplace carcinogens and particulates.
Yet our ignorance about what exactly is going
on is breathtaking. “For most exposures,
probably the things you’re breathing right
now, we’re not really sure what they’re doing,”
says Snyder.
Now he and others are attempting to
spearhead a revolution in understanding how
our environments make us sick. “It might
sound similar to what has been done in the
past, but now we’ve got this big concept,” says
Michelle Bennett at the US National Cancer
Institute Center for Research Strategy. Its name
is exposomics, and big it certainly is – it aims
to measure everything we are exposed to
throughout our lives and link this with
effects on our health. Can that ever succeed?
The notion that the environment can be badfor our health is nothing new. Cholera and
the black death were once blamed on noxious
gases emanating from rotting matter, and
malaria literally means “bad air”. We now
know that these are infectious diseases
caused by microorganisms. But in the past
century or so, it has become abundantly clear
that exposure to things such as dust, smog,
chemicals and radiation are a different,
insidious, long-term health hazard.
This was the birth of the discipline of
toxicology. For most of its existence, it
consisted of studies of short-term exposures
to individual toxic substances. Around the
turn of this century, however, it became clear
that this approach was lagging behind other
areas of health science. In particular, the
Human Genome Project moved genomics
on from sequencing genes to looking at the
complex interplays between many of them.
The project was declared complete in 2003,
but in 2005 Christopher Wild at the University
of Leeds, UK, who later became head of the
International Agency for Research on Cancer,
pointed out that despite this success, we
were still largely in the dark about the causes
of chronic illnesses.
For most of these – cancer, diabetes, asthma,
dementia, cardiovascular disease and so on –
genetic susceptibility was turning out to be
only a fraction of the explanation. By process
of elimination, things that happened during
our lives – environmental exposures – were
an overwhelmingly more influential factor in
mortality risk. But exposure to what, exactly?
To fill in this huge gap, Wild proposed
complementing the Human Genome Project
with an even more ambitious enterprise, one
that would ideally measure lifetime exposures
to everything in our environment and link
those to disease risks. Exposomics was born.KY
LE
ELLINGSONWild admitted that the goal was “extremely
challenging”. He wasn’t wrong. “The human
exposome is vast, it’s highly dynamic”, says
Snyder. “It’s a big ambition,” says Annette
Peters at the Helmholtz Centre in Munich,
Germany, “but I think it’s the right one.”
The alternative is that millions of people
continue to die preventable deaths. The upper
figure of 12 million deaths each year from
the cumulative effect of potentially harmful
environmental exposures, or “insults”,
represents around 20 per cent of all deaths