This Is Big News from the BBC: Herring Lung? Are They Kidding?
By Paula McGrath and Cathy Edwards
Health Check, BBC World Service
A healthy and delicious dish, but modern herring processing may cause health problems in some workers
Fish
has been a key source of protein for humans throughout recorded
history, but getting it to the dinner table can be a dangerous business.
Modern techniques have addressed many of the hazards of old,
like flesh wounds from the knives used for filleting. But they have also
introduced new ones.
Now Swedish researchers are warning about the risks to workers in the herring industry of asthma and allergies.
Their study, published in the Annals of Occupational Hygiene,
found high levels of fish protein in the air close to fish filleting
machines, thrown out by the machines and by the high-pressure hoses used
for cleaning.
These tiny particles can be inhaled deep into the lungs, triggering health problems in some workers.
Oily fish: good for the heart, not the lungs?
Herring is a popular dish in Scandinavian countries like
Sweden, especially at Easter and Midsummer. In the north they prefer it
with a mustard-based dressing, whereas in Stockholm pickled herring is
popular.
It is an oily fish, high in omega-3 fatty acids, and known to be good for the heart - when you eat it.
Breathing it in is a different matter.
Dr Anna Dahlman-Hoglund is one of the study's authors and an
occupational hygienist at Sahlgrenska University Hospital in Gothenburg.
She told Health Check
that over the past decade some of her patients who worked in the
fishing industry had developed breathing problems, including asthma.
So she and her team decided to look at their working
conditions, measuring the quantity of herring protein in the air at
various locations inside a fish processing factory. Smaller monitors
were worn by some of the workers.
She found workers had high exposure to the fish particles,
and attributes this to the filleting machines and high-pressure cleaning
jets casting particles into the air.
“Start Quote
When these patients aren't at work they feel much better, so it's very related to their work situation.”
Dr Dahlman-Höglund
Occupational Hygienist, Sahlgrenska University Hospital, Gothenburg
Previous research has shown that
inhaling these particles causes breathing problems, either because the
tiny particles irritate the lungs and airways, or because of an allergic
reaction to the protein.
This phase of the study just measured protein levels in the
air, without looking for a correlation between these levels and workers'
breathing problems. But Dr Dahlman-Hoglund says there is a clear link
between the illnesses of some of her patients and where they work.
"When these patients aren't at work or are on vacation, they feel much better, so it's very related to their work situation."
From tennis elbow to herring lung
Certain jobs have specific health risks attached to them, and
"herring lung" could be added to a long list including tennis elbow and
writer's cramp.
Like the herring workers' condition, many other occupational
diseases are respiratory. Hair salons, bakeries and metal factories are
some of the other places where workers are at risk from breathing
particles into their lungs.
Occupational asthma is now the most common work-related lung
disease in the UK and accounts for an estimated 20% of cases of new
adult asthma.
Proteins in the air, like those from fish and flour, are more
likely to cause problems because they are allergenic, says Dr Joanna
Szram, a Consultant in occupational lung disease at the Royal Brompton
Hospital.
"Fish processing workers are a known at-risk occupation, seen
in population studies and reported to registries in many countries
including the UK."
Occupational health hazards
Any kind of dusty environment can cause breathing problems.
However, most clinicians agree that asthma has more specific causes.
An estimated 90% or more of occupational asthma is down to breathing in particles known to cause allergies.
People most at risk include bakers, food workers and those working with animals.
Other causes include inhaling certain chemicals released in processes such as paint spraying and platinum refining.
But only a minority of people will suffer from asthma after breathing in fish proteins, Dr Szram says.
"In a factory population, occupational asthma generally
affects a minority of the workforce, unless exposure levels are very
high. In the UK, about a third of people have increased susceptibility
to allergies, and their risk of developing asthma will be higher."
New machines, old factories
Sweden only has a small fish processing industry, but the new
research has implications for the millions of fish processing workers
all over the world.
If people have occupational asthma, they may need to find
other work. However, there are ways to lower the risks by minimising
exposure.
Part of the problem for the fish processing industry is that
new machines are being used in old factories with poor ventilation, says
Dr Dahlman-Hoglund.
The research team advised factories to improve their
ventilation and use traditional methods to clean their floors instead of
high pressure hoses.
In addition, the air monitors worn by the workers in the
study allowed them to see when and where they were most at risk, and
change how they worked accordingly.
Michaela Archer from Seafish, a UK fish industry body, says there are a number of things companies do to protect workers.
"Where people are prone to such issues, companies can provide
a range of safeguards such as breathing apparatus, guards over
machines, protective clothing and health and safety training," she
explains.
Just knowing the problem exists is an important first step, says Dr Dahlman-Hoglund.
"Today when factories buy new machines they are not aware
that they can produce so many particles. When we told the factory about
it, it helped them to improve their working conditions."
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