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Current and emerging occupational lung diseases

Presented by Associate Professor Deborah Yates

Despite the widespread belief that occupational lung disorders have been largely prevented, there are disturbing trends worldwide about the re-emergence of traditional dust diseases and description of new lung diseases from new exposures.

In this presentation, recorded at the Healthy Lungs Forum in November 2019, Deborah explores current issues relevant to occupational lung diseases, which emphasise the need for vigilance and the dangers of complacency.

Note: From 1 July 2020 in Queensland the new national workplace exposure standard for respirable crystalline silica was revised from a time weighted average of 0.1 milligrams per cubic metre (mg/m3) down to 0.05mg/m3. This means that, from 1 July 2020, the reference to the workplace exposure standard for respirable crystalline silica in this presentation should be understood as a reference to the new standard of 0.05mg/m3.

About Deborah

Associate Professor Deborah Yates trained in Medicine at Cambridge University and completed her medical training at several London teaching hospitals. Later, she joined the Central Pneumoconiosis Panel in London and gained experience in a broad spectrum of occupational lung diseases including coal workers pneumoconiosis, silicosis, asbestos-related disorders and occupational asthma.

Since permanently moving to Australia in 1995, Deborah has continued her research and clinical interest in occupational and obstructive lung diseases. She is a Senior Staff Specialist at St Vincent’s Hospital, Sydney, Conjoint Associate Professor at UNSW and Co-Chair of the Coal Mine Dust Lung Disease (CMDLD) Collaborative Group and is active in the Thoracic Society of Australia and New Zealand (TSANZ) and Royal Australasian College of Physicians (RACP).

Run time: 29 minutes 03 seconds

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Associate Professor Deborah Yates: My name is Deborah, and I'm a thoracic physician working in Sydney. And I'd like to thank everybody for inviting me to talk here about a subject, which I'm passionately committed towards.

I have a background in both occupational medicine, and also in respiratory medicine. And I currently practice as a thoracic physician, and actually I'm working in the hospital as I talk, because I'm on call. So I have turned off my phone just for this talk, you'll be pleased to hear.

I'm also a member of the Black Lung Center of Excellence in University of Illinois, in America, and have a number of different conflicts of interest. But I should add that I don't usually get very much paid for some of these things. So I hope there's no obvious complex, and I'm not paid by any industry. And I'm really here for the patients, and hopefully, also, for the workers.

So I'm going to give you a quick run through, okay? This is not going to be an extensive description of all the different occupational lung diseases, because, fascinating as there are, we don't have enough time for this. But what I'm going to do is give you a really conducted tour of the sort of problems with occupational lung, which have been re-emerging in the last, well, actually probably about the last five or 10 years.

I'm going to talk about how easy it is to have complacency, and how we have all been caught napping, really, on this particular problem in Australia in the last 10 years or so. And I'm going to also talk about possibilities of how we can change for the future, and how we can all contribute to making our patients and our workers have a safer and more useful future.

Just to start, with the spectrum of occupational lung diseases, I've put a little diagram here of all the different parts of the lung that can be affected. You'll notice, that you, when you breathe in air, it actually goes down through your nose, and your nose is very good for trapping a lot of those particles.

But then, when it gets down into the trachea or the windpipe, it can have effects there, but I'm not going to talk about those, but they do include things like laryngeal cancer, which is a well acknowledged secondary effect of asbestos. And then you can go down into the large railways of the lungs, and as you go further down, you'll get down to what we call the alveoli, which are these sort of grape seed things that you can see here.

I don't know if I can make it ... Oh, sorry, I can't. Anyway ... I'll go forward again.

Really, if you look at the occupational lung diseases, they can affect any part of the respiratory tract, but the place that they affect depends pretty much on where the dust is actually inhaled to. So the things to remember about with the inhaled agents is that they're really, really common in the workplace.

And you as occupational hygienists and as workers will be more aware of that than I am. And there's really every variety of possible hazard that's there. And the thing to remember is that it's probably the particles that you can't see that are actually more important, the fumes and the vapors, and the really, really tiny inhalable agents, because these are the small ones that get down into the peripheral airways. And they're the ones where you can actually have an acute inflammatory response.

The other thing that's really important to remember is that this is not like the ordinary industrial accident. You don't see an effect immediately. These take 10, 20, 30, and with mesothelioma, now up to 50 years to actually become manifest. So it's really, really easy for all of us to forget that they actually exist.

And as a person, as a human being, you cannot forget the occupational exposures that happened 20 or 30 years ago, which is one of the reasons I think it's really important to document things at the time and keep those records. And it has to be for a long time. And I recommend keeping them in paper, not electronic form for the moment, because we don't know how long the electronic things will actually survive.

The occupational component, as well, is really easy to forget. Because the diseases that will manifest have the same symptoms as those that come from non-occupational diseases. So, for example, a cough or a cold is often dismissed by most people as something you picked up from the children or something, which is something caused by smoking. But that may not necessarily be the case.

You may have more than one disease happening at the same time. And we're all very aware of, certainly at the moment, of the fact that there are a lot of environmental exposures that will also contribute. And the smoke haze in Sydney and here is really a wonderful example of how environmental factors can really make a big difference to people who have pre-existing problems.

I put up a couple of pictures of the sort of exposures that you and I, and probably you more than I, see almost every day. And then that's a picture of what Sydney was like just before I left, not a good look.

How common are occupational lung disorders in Australia? Well, I'm embarrassed, really, to say that we have no good data. There's no centralized collection system. There's very patchy collection. Industrial accidents and injuries and compensation claims are the main ways of actually keeping any sort of data. And they're really pretty poor.

Whereas if you look at other places, particularly Northern Europe, where they've had really probably sort of nanny states, as you'd call it, for a long time, you have much better information. And I'm sad to say that Australia is one of the leading places in the world with regard to occupational lung disorders, even on the very scanty figures that we have.

If you look at this graph here, you can see that Australia is the green diamonds. So the green diamonds are not quite up there at the very top, but they're pretty near, so high up in the league table.

But unfortunately, it's not really well recognized, either by the community or by politicians, though I think this is changing now. And the burden of disease is probably vastly underestimated. So for every case that you see or that you hear about, you could probably at least quadruple it.

There were very many common untrue assumptions, and we all make these. The first one is that someone who has no complaints with regard to their lungs has no disease. Well, that's actually not true at all, because you only start showing the effects of lung disease when you've got quite bad lung disease.

This is something I see every day when the people who smoke, they come and they said, "Well, I've been fine for 30 years. Why am I suddenly feeling sick?" And the answer is because we have a lot of reserve.

We have been given two lungs, we've been given two wonderful lungs, which worked really, really well. So you have to get really, really low in terms of your functioning status before you start noticing anything.

The second assumption that we all make, myself included, is that when anybody smokes, we tend to always attribute all those symptoms to smoking. Well, that may well be true in some cases.

But as I said on one of the earlier slides, there are many, many factors that may well be coming into play. And we are just being unsophisticated, by assuming it's just due to one exposure.

The other thing is that we have to remember that even if the dust levels, when they've been measured, have been within the exposure limits, that doesn't mean that there's no disease. Because the dust exposure limits have been set intentionally with producing a small lump amount of disease. And there are lots of individual disease variations.

It's like throwing seeds on a field. Some will grow, some will hit the stony ground, and some people will be much more susceptible with the effects of dust and fumes and vapors than others. And we're only just beginning to learn about that in medicine, and what are the actual genetic factors, and maybe acquired factors of the causation for this.

The other thing you remember is that workers, on the whole, do not come and complain about symptoms early. They come and complain late. They're not, on the whole, whingers. They're actually trying to keep working. They're trying to keep their practice up, trying to actually pay for their families.

They're the ones who are the last ones who actually, really, moan unnecessarily. Although there is a prevailing ideology, that's not the case. That's not actually true.

The other thing is that these diseases are incurable. Now, this is the beginning, I think, of a change in the whole idea about occupational lung diseases.

A, we can prevent them, and B, the vast majority of occupational lung disease, which are not actually the ones that we know most about, but the ones that are under-recognized, like COPD and asthma, we have very good treatments for them now. So prevention is much, much, much better than cure. And you are the ones who can do all of this. I can't do the cure bit, but I'm trying.

So just to emphasize, and because I can't resist this lovely slide. Yeah, smoking is one of the really, really bad things. And you will end up as a skeleton if you smoke, and it's hard.

But there are many other causes. And as you can see, this sort of dust exposure is hopefully something which is not occurring nowadays, that certainly has done historically. And I still have patients coming in showing me that they actually have the dust like this with the man with the mask, despite regulations.

Smoking and dust exposure is a property equivalent to each other, rather than cancelling out each other. So the effects are usually additive. With asbestos, some of them can be multiplicative, but usually it's additive, particularly with the mineral dust exposures. And the classical occupational lung diseases are, unfortunately, resurging in Australia.

There's coal workers' pneumoconiosis or black lung, which is easier to pronounce. There's silicosis, in particular, artificial stone silicosis, which I'm going to talk about a little bit now. We mustn't forget the roles of allergic sensitization, which I'm not going to really talk about, which is a fascinating new area. And in particular, things like thunderstorm asthma.

You may have heard about the thunderstorm asthma epidemic in Victoria, a couple of years ago, 2,000 people admitted to hospital within a very short period. That's actually relevant for occupational exposures, as well as pollution. Although you wouldn't think of it out of water intuitively. And then there are the lung cancers, asbestos, silica, diesel exhaust, and so on, and very under-recognized the occupational asthmas, the occupational lung cancers and the occupational interstitial lung diseases, which I don't really have time to talk about today.

This figure is just taken from the Queensland government figures on mineral dust, lung disease. And as you can see, despite the fact that there were thought to be no cases at all, there have been 120 cases reported as to 30th of September, 2019. So this is the coal miners. And those were totally missed in previous years.

You're all aware of the resurgence of coal workers' pneumoconiosis, of the black lung inquiry, for Black Lung, White Lies, which I actually went and gave evidence to. And really, I have to say, this is a catastrophic, this is being caught off guard.

These diseases were there, they were being missed. There was a sense of complacency. And I think the one good thing about this is that we have been woken up, and woken up really hard, in a hard way, to recognize that these diseases are actually still there.

We should not have a single case of this disease nowadays. This is a disease of the 19th century. It should not be here, not even in the 20th century.

Artificial stone silicosis is again another thing, which is really rapidly evolving, and which was touched on in the introduction. So artificial stone silicosis is a classical disease, which has now recently been described in association with the [inaudible 00:11:22] that you and I all love.

I have to say, they are really lovely. If you go into any hotel, if you go into any bar, you'll see these beautiful artificial stone ones. And the reason that they'd been used is they're cheap. Okay?

They're cheap, they're durable, they're the 21st century's answer in terms of modern technology. They're mainly produced in places like Israel or China or Vietnam, and they're an engineered stone. So they're actually an amalgam of very, very high levels of silica, in association with resins, and often metals.

The characteristics of these stones is that they're actually imported into Australia, they're not produced in Australia at all. And then they're moulded outside and cut to shape, and put into, for example, all the new apartment blocks and all the new hotels that are being built in Queensland. And they're cut locally, and they used to be dry cut.

They're not dry cut anymore, because of the fact that you actually have read legislation this now, and mandatory reporting of all the cases. But I can tell you that the dust levels in some of the measurements have been a thousand times over the permissible exposure limits. So very, very high exposures, and people are not necessarily using respiratory protection, or they haven't done historically. Let's hope they're all doing that now.

So the levels of exposure are really, really high. And what it does is, it produces a really rapidly progressive silicosis, a really nasty disease. This is an example. This is the first case of artificial stone-associated silicosis, which we actually found in New South Wales, even though it didn't exist, of course, because nobody knew it happened in Australia.

This is my patient who had artificial stone silicosis, who was transplanted. We described it in 2014. So there's been a bit of a gap, between when it was described, and when action has actually been taken. But you can see how severe his disease was with the slide on the left.

Then he actually had a lung transplant, and now he's doing relatively well. But this is a lung transplant for a totally preventable disorder. And he's not the only one.

I have quite a number of cases. One in particular is this young man. And I feel really sad about this. This is a young man who was 45, young, in my terms, because I'm a bit older than that. And he had been working out in Bankstown, which is Western Sydney, in artificial stone.

He was very nice, a very nice sensible chap, who'd actually initially ... He was very bright. He'd initially gotten a job as an engineer at Sydney Uni, but he later dropped out because he felt that he had family commitments and other things to do.

One of his friends was actually working in the artificial stone industry. He said, "Why don't you come and join us? There's lots of money to be made, where you can actually have a good job."

So he set up his own little company. And there were four of them, and they're all working in this company, but they had no knowledge. They had no checks. They had no information at all about silica.

He actually worked with daily exposure to artificial stone and developed acute, I'm sorry, progressive silicosis. And by the time he got to see us, he was actually so ashamed, because he was from an ethnic background.

He felt he had the need to support his family. He felt ashamed of not carrying on at work. And he actually went back to work. He refused not to, not to work. And he didn't turn up to his clinic appointments.

To cut a long story short, he actually died. He died of this at the age of 45, which is awful, absolutely awful, and totally preventable. So this is just an example, but there are many cases. And in Queensland, on the Gold Coast, there are now almost 200 cases of exactly in this sort of circumstance.

In addition to artificial stone silicosis, in addition to classical silicosis, there on a large number of other things that are associated with silica exposure, which we've pretty much forgotten about, but which I will mention here. Lung cancer, chronic obstructive pulmonary disease, interstitial pulmonary fibrosis, probably sarcoidosis, which is an unusual lung disease that we see at time to time, and a disease of the peripheral part of the airways, which is called obliterative bronchiolitis. And it's really insidious, because you can't pick it up early, either on lung function or on CT.

Then there are other things that occur. There's a type of arthritis which occurs, which we've recently just written up, and should be screened for already all the time, which gives you thickening, and painful fingers, and a phenomenon where you actually get cold blue fingers with the cold.

You don't notice that much in Queensland, because it's warm here, but it's called Raynaud's phenomenon. And this is actually probably pretty common in men who are exposed to silica worldwide.

You also get chronic kidney disease, and probably also other cancers. So we're now just beginning to recognize that silica exposure, crystalline free silica, is actually associated with a whole range of other diseases, not just with classical lung silicosis.

The asbestos-related diseases, as well, are really something which we shouldn't forget. We've known about these for many years, and we've known about the varied and many manifestations. Pleural plaques are probably the common asbestos-related disorders, and they're really relatively benign, but they're very, very common. They're just a marker of asbestos exposure.

As you can imagine, a lot of people get very worried about them. And as such, the main thing to be done with pleural plaques is to keep people reassured, and keep an eye on them, to make sure that they're not going to develop the really dreaded other types of diseases.

Asbestos-related pleural effusion is really rare, but often missed. And you can get a disease called diffuse pleural thickening, which affects both sides of the pleura, and gives you a very sort of insidious long, breathlessness again, mainly missed. And then, you can get actual fibrosis of the peripheral parts of the airways, the lung scarring, which is known as asbestosis.

Asbestosis is pretty unusual nowadays. And so, it should be, because it's dose-related. So the people who have asbestos exposure usually have to have a higher dose to get asbestosis, so we're seeing it less than this. We shouldn't be seeing it at all. And it occurs 30, 30, 40 years after the initial exposure.

Then there's asbestos-related lung cancer and the dreaded mesothelioma, which is a picture of here. You can see how the lung is surrounded by this horrible cancer, which is essentially still untreatable.

There's a lot of research being done into treatment for it. There are new treatments, but unfortunately, the treatments have not been in any way as effective in treating mesothelioma, as they have with lung cancer.

The other one that, again, is pretty much under-recognized is chronic obstructive pulmonary disease. Now you're probably all aware of this. You probably all have grandparents, parents who have COPD, because this is really, really common. And it's the commonest disease, due to cigarette smoking. So the little old lady who sits on the bus, coughing away, or the little old man, probably has this.

Basically what happens is that the toxin, often cigarette smoke, is inhaled. And the conducting airways, the tubes that lead down to the lungs, become very inflamed and sore. And that the peripheral part of the lung, this great light structure, which is involved in gas exchange, basically goes from being a nice series of grapes into a baggy sort of balloon, which doesn't really work.

Both of these are encompassed in chronic obstructive pulmonary disease. And you can get chronic bronchitis, where you cough up a lot of phlegm, or you can get emphysema, or you can get both, okay?

We now know that these are very well associated with occupational exposures. Dust, fumes, and vapors, all contribute. Even cleaning ladies will get COPD. So you don't have to have huge doses of this. And they're probably about, 10% to 15% of the population have COPD, which is solely related to occupational cause.

If you think of the number of cases of COPD that exists, this actually represents millions of people, and billions worldwide. So you can imagine it's a very, very important topic, which is very under-recognized.

You can't distinguish from occupational, from non-occupational causes, without taking a very, very good history. And you can't distinguish on a histologic, on a lung basis, unless you actually take some of the lung out, and do things like fiber counts on it. So it's a very difficult call to make, which is probably one of the reasons it's so underestimated.

And it is definitely caused by other things like welding fumes, like silica, cadmium exposure, and a number of different agents. So this is a very under-recognized disease, but there are standards of care that have been developed.

A colleague of mine called David Fishwick published on this hot topic in 2015. But this is probably the next, if you're thinking about next waves, this is probably going to be the next wave of occupational lung disease, when we actually start to understand and report some of these factors, but COPD is treatable. COPD is treatable.

We have very good treatments for it nowadays. We have, even more importantly, extremely good preventative measures. So we need to be diagnosing this in our patients early, and in our workers, and taking them away from any agents that could make it worse. And that's primarily cigarette smoking, but any dust, fumes, or vapors.

There are other lung diseases, many lung diseases. There's occupational asthma. More than 2,000 agents can be described. Again, potentially anybody can have occupational asthma, or more fancy things, like hypersensitive gene pneumonitis, and diffuse dust fibrosis, I don't have time to go into them at the moment, but very interesting.

There's also, pneumococcal pneumonia is something that you tend not to think about, but actually, it's, you get more of bacterial pneumococcal pneumonia in welders for some reason, probably due to the iron that they inhale. And in the UK, they actually vaccinate them against pneumococcal pneumonia, because it's a good preventative strategy.

There's other infections, things like tuberculosis, in people with silica exposure, not just silicosis, but silica exposure. And again, something which is eminently treatable, and particularly high in people who have come from an immigrant background, or who make frequent trips back to, say, Vietnam or China. And then there are some very rare lung diseases, which I love diagnosing, because they're great fun to find.

We mustn't forget about the occupational lung cancers. Again, very under thought of, have a large variety of different causes. Asbestos is something one tends to sort of think about.

One tends to forget radioactivity, nickel, chromium, salt, arsenic, mustard, well, mustard gas is much less common over here, printing inks, possibly, and the other thing is diesel exposure, which of course is a well known cause of occupational lung cancer.

The other thing about lung cancer is that we can pick this up early, and now we can treat it. If you find a lung cancer early, and you resect it, they have a 95% five- year survival. This is really important for people, but we don't screen for it. Perhaps we should be.

There's some novel exposures. I don't have time to go into all of these. But I would recommend, anybody who's interested, to just have a little look online.

Actually, the Center for Disease Control in America is a very good source of information about these is popcorn lung, which is an interesting bronchiolitis obliteran, which was associated with inhalation of a particular diacetyl agent from popcorn, working with popcorn in the States. So next time you go to the cinema, don't use too much popcorn, although it's probably not a problem here.

There's nylon flock lung, which again was an obliterative bronchiolitis, which was associated with the nylon flock from cutting nylon fibers. You know, the stuff that they use on those pretty Christmas cards with that? That can give you a lung disease.

There are large number of other different types of exposures that can give it to you. Gulf War Syndrome and World Trade Center disaster, again, very interesting, because these people who were actually exposed to dust fumes and vapors from those two particular exposures were very carefully followed up.

For example, with Gulf War Syndrome, they actually had baseline exercise tests on a lot of these soldiers, because of course, when you're a soldier, you get screened. You go off and you do a run round, however many kilometers it is, and you wear the backpack. And they can all do it, and I can't, but at least they know how far they can go.

Then after the Gulf War, they had a number of people from all over the world. I mean, it wasn't just the Americans or the Australians. It was also the British and the French sometimes. And they were all complaining of breathlessness, which they could then document, because they actually could find how much less they were able to do on their runs.

To cut a long story short, when they actually did invasive tests and biopsied them, they had this bronchiolitis obliterans. And what that has done is it has opened our eyes about how unrecognized toxic exposures can produce quite unusual reactions in the body, which are very difficult to detect early on.

Therefore, really, the lesson from all of this is that the lungs are not designed to have anything inhale them other than air. If we inhale anything, wood smoke, cigarette smoke, fumes from gases, fumes from explosions, fumes from bombs, like in the Gulf War, then we're putting ourselves at risk, and we really need to work as hard as we can to avoid those.

With regard to the symptoms of occupational lung disease, you will hopefully, if they're occupational hygienists or workers, they are completely the same as any other symptoms. Okay?

You're not going to notice them. And they're very non-specific. Cough is the commonest, wheeze, breathlessness and chest pain. You don't get the bad symptoms until quite later on. Coughing up blood is something which hopefully will never happen to anybody here. And when it does happen, it's really a medical emergency, and it does need urgent review.

We assess lung disease, using a series of different investigations, which are not terribly sensitive. When I say sensitive, I mean the ones that will pick up early disease. We have a number of different occupational exposure questionnaires.

We have an examination which is useless, to be honest, except in very severe disease. So the normal examinations should be normal. There should be no abnormalities in the chest. We have very basic examinations, spirometry and chest X-ray. And then we have very fancy investigations, which are really being very much better.

Spirometry, I'm not going into, but you know this, you know about this, and this is a very basic investigation. It has to be performed properly. There's no point in doing it, unless you can perform it properly, but it's actually quite difficult to do properly.

We have set recommendations, and I have to say that a lot of people are unable to do this, or unable to do it properly. So, but they can, with proper training. And there are very good recommendations. Now we know worldwide how best to perform it.

There are more important tests, more sophisticated tests that can be done. We now know that that lung function is variable. It depends on what part of your life you're in. And that we have a different trajectory, depending on our underlying genetic and environmental and childhood exposures.

I hope, for example, I'm at the top of the list and I'll be having a good lung function, I won't get bad, and get breathlessness at the end. But some people who, for example, have had early childhood problems will end up with very bad lung function. And lung function itself is a predictor of death.

So you need to know which trajectory your particular worker is on. You need to do as many FEV1 spirometry readings as possible, the more, the better. It can't be overemphasized. [inaudible 00:26:42] is the next level of expert of finding disease.

Again, we use the same methods. We don't use anything very much different, but perhaps we should. We now have modern techniques that are improved. We know that CT scanning is better than chest X-ray. We know that sophisticated lung functions are better than just spirometry. And we can do these.

We have computerized techniques, we have portable machinery, but we have to take into account the disruption and the anxiety of costs that occur with our patients. Because naturally, they're very worried about any abnormality that is detected.

So just to conclude, with a rapid romp through the most important things that you will hopefully will ever hear, we have really good data now about preventative strategies, about the incidents, about what we need to do with occupational lung disease. And we do know that they're preventable.

We are under-recognizing them in Australia, but I think that we are getting some way towards actually documenting them. And I have to say, particularly in Queensland, I think Queensland is not only leading Australia, but actually leading the world, in terms of the response to silica. And I think you all need to be congratulated for this.

The old diseases are really making a reappearance, and we must be vigilant. We must remember that we have to keep pushing on these, and we'll need to keep pushing for 20-30 years, because this is the latency period of them. It's not something which is like a workplace accident.

And we need to look into new ways of actually making sure that we pick these cases up early. And if one does this, if we all work together to do this, we could save many lives.

And in addition, we could, also need to remember, that we should push for the traditional things, like stopping smoking. We can actually help with the patient's general health, and the patient's general attitude towards this, as well as actually detecting these diseases. And I think the press has actually really helped us a lot with regard to this, because the profile of this has gone very much further.

In conclusion, I'd like to encourage everybody to be vigilant, to be aware, and to remember that really, we shouldn't see any of these diseases at all, and that any respiratory symptoms are something which need to be taken seriously. So thanks very much for your attention.