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Episode 5- Kate Cole, Silica - Part 1 1
3M Transcript for the following interview: Ep-5-Kate Cole, Silica Part 1
Mark Reggers (R) Kate Cole (C)
Introduction: The 3M Science of Safety podcast is a free publication. The
information presented in this podcast is general only, and you should always seek
the advice of a licensed or certified professional in relation to your specific work or
task.
Welcome to the 3M Science of Safety podcast presented by 3M Australia and
New Zealand Personal Safety Division. This is a podcast that is curious about the
signs and systems of all things work, health and safety, that keep workers safe and
protect their health. I am Mark Reggers, an occupational hygienist, who likes to
ask the questions Why, How, and Please Explain. Whether you are a safety
professional, occupational hygienist, or someone with any level of WHS
responsibility in the workplace, maybe you are a user of safety products or maybe
you are a bit of a safety nerd who finds this stuff really interesting, then this is a
podcast for you.
(R) Today we are talking all things silica with Kate Cole. We had a fantastic
conversation with Kate and it went for quite a while because it is a fair bit of
information, so we have decided to split it into two parts, and this is part 1 of that
conversation with Kate Cole. Enjoy!
Today we have Kate Cole from Ventia talking all things silica. How are you, Kate?
(C) I’m great, Mark, how are you?
(R) It’s a fantastic day today, I get to talk to you all things silica which, for you
know, a safety nerd and occupational hygienist that sounds interesting. Kate is a
certified occupational hygienist who has worked in the construction industry for
Episode 5- Kate Cole, Silica - Part 1 2
almost two decades on projects in Australia, Hong Kong, and the USA. She holds
degrees in Science, Engineering, and Occupational Hygiene, and works on major
projects involving complex contaminant land remediation and large scale
underground tunnelling. She is currently the manager of occupational health and
hygiene with Ventia. Kate works across most tunnels under construction in
Sydney. She is currently supporting transport for New South Wales on Australia’s
largest public transport infrastructure project, the Sydney Metro, as the
occupational health and hygiene manager. So, you’re the manager of two things,
Kate, is that right? Am I reading that right?
(C) Yes, very capable, very busy.
(R) Very busy, I can only imagine. One last thing about Kate which I think is
interesting, so I am going to ask her a little bit later about it. In 2016 Kate was
awarded a Winston Churchill fellowship where she visited numerous tunnel
constructions projections in Norway, Switzerland, the UK, and the USA to
investigate best practice to prevent illness and disease in tunnel construction
workers. How was that trip, that would have been a fairly big one?
(C) Oh, the Churchill Fellowship was absolutely amazing. It was great to go and
see how other countries and other organisations tackled the key issue of silica dust
control in the really high-risk cohort that we have.
(R) I have a couple of questions a little bit later once when we get to it, what are
your learnings from there, but [K: Don’t get too excited] I won’t get too excited, we
are talking about silica, and I know it is a very exciting topic. So, let’s start right
with the basics. What is silica?
(C) Well, silica is the term commonly used to describe respirable crystalline silica.
And when we talk about silica or silica dust, we are referring to that really, really
Episode 5- Kate Cole, Silica - Part 1 3
fine dust that is generated from many different types of activities, and it is called
silica dust because it mainly consists of quartz or has quartz in that really fine
respirable dust.
(R) So different types of rocks. Are there different amounts of silica, or it is always
a set percentage of silica…?
(C) Definitely, different types, so in Sydney particularly is quite pertinent, where we
are today, so Sydney sits on a bedrock of Hawksbury sandstone and there is shale
on top of that, and shale typically has around 30 percent quartz in it, so if you cut
or rip into shale then you’re going to generate silica dust, but more concerning is
Hawksbury sandstone, because Hawksbury sandstone has over 75 percent quartz,
and in some cases, it is closer to the higher 90 percent, so any type of disturbance
of that rock, whether it is tunnelling or cutting or ripping or crushing the sandstone
you are going to be generating quite significant proportions or concentrations of
silica dust.
(R) So, all those tunnelling projects that you’re working on and around, that is going
to that Hawksbury sandstone, that 70 to 90 percent sandstone? Or …
(C) Yeah, it is, and that is why it is a key area focus for the tunnel construction
industry. But that’s not the only industry where you come across silica dust, so
kitchen benchtop manufacture is quite pertinent, because especially with
countertops and engineered stone, they will have quite high proportions of quartz,
as opposed to I guess your traditional marble which has a really low proportion of
quartz, you might only have like 2 percent in marble, whereas engineered
countertop benchtops might have over 90 percent, so it is a really big difference.
And the construction industry in general comes across silica dust quite a bit, with
concrete and cement containing anywhere from you know, 15 to 30 percent
Episode 5- Kate Cole, Silica - Part 1 4
quartz, so any type of concrete work for shotcrete, that is where you will find quite
a bit of silica dust in the air as well.
(R) You just think about concrete, I mean every building has a level of concrete,
driveways, homes, I guess that is a fairly standard activity across all industrial and
non-industrial places frequently.
(C) Definitely, and my main background is in construction, so as you can imagine,
for myself and other occupational hygienists in construction, silica dust exposures
form a key area of focus for us in this industry.
(R) I can imagine. So, you mentioned respirable crystalline silica, so the really fine
stuff, are there other different types of silica?
(C) There are, so silica also refers to amorphous silica. Amorphous silica is a lot less
toxic when we are looking from an occupational hygienist perspective, we are
looking at protecting worker health, we are really looking at the respirable
crystalline silica, so the quartz type of silica rather than amorphous silica.
(R) So, you mentioned construction. What about quarrying slate, are there are any
sort of other industries other than the ones you have mentioned so far that people
should be aware of if they are not aware of?
(C) Yeah, so in addition to those, so ceramic manufacture, brick and tile
manufacture, foundries, and just being in Sydney and walking through The Rocks or
walking through any beautiful heritage area, you will pretty quickly see just how
many of our buildings are constructed from that gorgeous sandstone, which is
beautiful to look at, however it can be quite hazardous to maintain, with tuck
pointing and cleaning of that type of sandstone. They represent really key tasks
Episode 5- Kate Cole, Silica - Part 1 5
that we would be looking at to make sure that we control those exposures as far as
reasonably practical as much as we can to protect the health of those workers.
(R) So, I guess it is not the, you can try to maintain some of those buildings, it’s not
like you can get up there with some Scotch Brite or something and just sort of wipe
it off [K: No] or scrub it off, we’re talking fairly…
(C) Preferably not
(R) ...abrasive…actions to maintain those, it is a fairly good point, not just the
construction but the maintenance of those particular buildings.
(C) Definitely.
(R) What are some of those activities. You mentioned some of the industries, what
about the actual activities, now we spoke about you know, maintaining, so maybe
blasting, what are some other activities that people should be aware of?
(C) Um, I think one of those most common ones we see is when we’ve got workers
who are doing any kind of hand-held polishing or hand-held grinding activities, and
also concrete saw cutting activities, whether that is in a road or a wall or any time
of hand-held tool that cuts rock or stone is a key risk area, and something that we
really need to focus on. How do we control the dust that comes out of those
activities, and recognising that it is not just dust, and you are probably used to
seeing dust in the construction industry, this is probably not something new, but
however the dust that is coming from concrete and sandstone and other sorts of
rocks does have really high proportions of silica in them. See we just have to be
conscious of that when we are looking at those types.
Episode 5- Kate Cole, Silica - Part 1 6
(R) So, you mentioned about dust and construction projects, and you know, you’re
driving along, and you see the dust, can you see the silica in those dust clouds? Is it
I see dust, that is absolutely going to have silica in it?
(C) Well technically no, you can’t see respirable crystalline silica because it is so
small, and I mean we are talking about dust that has a, not to get too technical, but
a median cut-off point of 4 microns, so this is very, very small. However, that sort
of dust isn’t just there by itself, it is normally co-located with big chunks of other
dust that you can see, so if you do see workers covered in a cloud of dust and the
dust is made up of sandstone dust, or concrete dust, then it is reasonable to assume
that that dust contains a pretty big proportion of respirable crystalline silica.
(R) As you said, you can’t see it, so it can’t be seen by the naked eye, so you’re not
going to rely on Oh, I’m pretty sure it’s not going to contain it, but I guess that is so
crucial I guess from a workplace point of view trying to identify, maybe we’re
cutting into that particular type of sandstone, what is going on there.
(C) Yeah, and that brings up a really good point about if you are a PCB or you are a
particular organisation that is doing or in charge of these particular activities, really
understanding what the inherent amount of quartz C is in the products that you are
using, so that is really from an occupational hygiene perspective, what we would
call hazard identification. So silica is difficult, I think, because you are not bringing
on a substance to your work site that has come in with a safety data sheet, you are
not bringing it on, you are actually generating it, and that in itself can be tricky
because the level of aware of, well, how much silica is in this product that then I am
cutting into, can be kind of mixed in construction. In some areas, there is a really
good level of awareness, and I will use tunnel construction as an example, a really
good level of awareness of the risks associated with crystalline silica and the level
of control that is needed. Then in other areas of construction, and particularly in
some, say, small businesses that may not have the funds or ability to have great
Episode 5- Kate Cole, Silica - Part 1 7
access to occupational hygienists and those types of technical experts, and the
level of awareness can be a bit less. So what those businesses can do is start to
have a look at, well, how much quartz do I have in the stuff that I am cutting into,
and what is in the cement that I am using, and what are some practical control
measures that I can put in place so that I don’t have to rely on the ability to see it to
actually control it.
(R) That’s a great point, I mean the basis of any risk assessment, whether you’re a
hygienist or a …… professional - what are we doing, what have we got, and what
are those particular things we may be generating as well. Are there other things in
the workplaces that may be causing exposures? I mean obviously we know we’ve
got our concrete, we’re cutting it, but there are there things that other people may
not be on the actual saw who may be getting exposure that workplaces should be
maybe thinking of considering?
(C) We would classify it in two ways, as a hygienist we look at primary exposure
and secondary exposure. And we look at secondary exposure, that is where you
are not necessarily generating the dust, but you just happen to be in the location
where unfortunately you are being exposed. That is one of the most common
types of exposures in construction, and I guess a really good example would be
what is termed a spotter. So, a spotter is generally a worker spotting a piece of
plant doing something, so making sure that people don’t come into that area for
example, making sure that there is, you know, a good level of area of separation
between a piece of plant and another piece of plant, or may actually be holding
some form of dust suppression to suppress the dust. And by the very nature of
what they are doing typically, they are using hoses like a high-pressure hose or
garden hose or any time of hose that’s got big water droplets, generally they are
not actually reducing exposure to silica. Because silica is really, really fine, and so
you need a really, really fine water droplet size that matches that same size of dust
to knock it out, but unfortunately those spotters, if they are using a garden hose,
Episode 5- Kate Cole, Silica - Part 1 8
are really just being put in a location where they are being exposed to really high
concentrations of dust, even though they may feel or think that they are actually
suppressing it using the tools that they have been given. So that is a key area that
we see a lot where those spotters are actually exposed to very high concentrations
of silica because of the nature of where they need to stand to do that particular job.
(R) So, the effectiveness of their control, their water, is really controlling that
secondary exposure you mentioned for all other people, you may be a visitor on
that site, you may be someone working in the office, whatever it may be, so that is
another key control point there. So, you have all these dust clouds, with lots of
silica in it, how much silica will cause harm to a worker, or is it a one-off exposure,
are we talking it takes time to have this particular negative health effect that we’re
going to ask you about a little while?
(C) Well, it is a chronic acting health hazard, but is also a carcinogen, so to be
honest, exposure to carcinogenic agents should be controlled, so far is reasonably
practicable, we shouldn’t be relying on a workplace exposure standard, and I use
that term, it is a legal term, it is referred to in the Work Health and Safety
regulations. The Workplace Health and Safety regulation has a workplace
exposure standard for respirable crystalline silica, and that is 0.1 mg per cubic
metre which is over an eight-hour shift. That may not be much to listeners, but to
try to put it into a visual perspective, imagine you have a 5-cent coin in front of
you. 0.1 mg per cubic metre is around a small piece of dust, it is a really, really
small amount that workers shall not be exposed to above that limit over their
working day. However, that doesn’t mean that you’re allowed to expose them to
just a little bit less than that. Crystalline silica is carcinogenic. We need to make
sure that we are controlling exposure as far as reasonably practicable, as low as
possible, and it is a chronic acting health hazard. That means that the more you are
exposed to it over a longer period of time that the higher your risk is of developing
illnesses associated with silica dust, and these aren’t small illnesses, these are
Episode 5- Kate Cole, Silica - Part 1 9
irreversible occupational lung diseases which are absolutely debilitating, like
silicosis and lung cancer and in addition to other things like renal disease, etc, so
this is incredibly important. And you will probably say, well, I drive past lots of
construction sites and I see these dust clouds all the time, and I guess that is
something that we hear as occupational hygienists quite a lot, but just because it
might be quite common to see it does not mean that it is acceptable, and it doesn’t
mean that we can’t change and do something about it.
(R) So that 0.1 mg per cubic metre, that workplace exposure standard here in
Australia, now you’ve done a bit of traveling with your fellowship, is that consistent
with other levels around the world, as obviously every country has different
exposure standards?
(C) Well interestingly no, it’s not. So, the US OSHA recently brought out their new
silica rule and what that did, amongst many other things, was reduce their
workplace exposure standard to essentially half of Australia’s workplace exposure,
to 0.05. Also, there are other groups in the US such as the American Conference
of Governmental Industrial Hygienists, the ACGH, so they have recommended the
threshold in a value or the equivalent of the workplace exposure standard to be
around a quarter of what we have in Australia. And, you know, some may say well
these are just numbers, what do these mean, and essentially it shows that other
countries internationally have really focused on the issue of respirable crystalline
silica and started to reduce the limit as more scientific evidence has become
available. However, in Australia our Work Health and Safety regulation doesn’t say
it is okay to expose people to 0.1, it really requires us to control exposure so far as
reasonably practicable and that is the maximum limit, so even though we might be
at 0.06 or 0.07 or 60 to 70 percent of our limit, it doesn’t necessarily mean that
that is okay if there are reasonably practical measures that can be put in place to
reduce it even further.
Episode 5- Kate Cole, Silica - Part 1 10
(R) Because those exposure standards are not lie in the sand, safe, and unsafe, and
that is because I guess people who are health and safety professionals would say
oh, we’re underneath that number, well, you could still get lower than that and that
is going to be a way better outcome for the workers than saying all right, we’re at
50 percent, that is acceptable, let’s go on to our next priority.
(C) And to put that into perspective, when OSHA did publish their silica rule, they
published a whole bunch of amazing documentation to support it, and one of those
involved a quantitative risk estimate of the actual new rule, and to summarise many
hundreds of pages into one key thing, it would be that the risk of developing this
incurable occupational lung disease silicosis at the current workplace exposure
standard in Australia has been quantitatively estimated to be anywhere between 12
to as high as 77 percent of workers if they are exposed to the current exposure
standard over their working life. That is a big variation, so I don’t think 77 percent
is acceptable, nor do I think that 12 percent is acceptable, but it just shows you that
wide degree of variation, and actually reducing exposures, all that will do is reduce
those numbers which is what we want to achieve.
(R) Do you think Australia will follow suit, so usually we sort of, when global trends
are happening, and not just in health and safety spaces, do you think Australia will
sort of lower that exposure standard sometime in the future?
(C) Well, I do know that Safe Work Australia are currently in the process of
reviewing the Australian Workplace Exposure Standards, which is great. However,
a standard, to be honest, is just a number if there is no compliance with that
number. And I think as an industry, and if I look at the construction industry
particularly, we would be better spent really pushing for better compliance with
our existing exposure standards rather than trying to lower a number that may not
even be able to be complied with.
Episode 5- Kate Cole, Silica - Part 1 11
(R) I think it is a fantastic point, you can lower the numbers as much as want, but
the focus has got to be genuinely controlling the hazard, and that can be done right
now irrespective of whatever number is out there in that workplace exposure
standard.
(C) Yes.
(R) You mentioned silicosis before, so I am assuming that is one of those health-
related diseases that silicosis cause, can you expand on what silicosis is, and any
other particular disease that may be caused by respirable crystallised silica.
(C) Well silicosis is an occupational lung disease. There are a few different types,
so there is chronic silicosis which you can get after about 20 years of exposure
also, or the latency period I should say is around 20 years after exposure. There is
accelerated silicosis, and that comes from very high exposures to silica dust, and
unfortunately in Australia we have actually seen some recent cases of accelerated
silicosis in kitchen stove top manufacture workers where they are exposed to really
high concentrations because of the high proportion of quartz in those benchtops.
And there are other diseases that are caused from exposure to silica such as
chronic obstructive pulmonary disease, commonly known as COPD, in addition to
lung cancer and also renal disease as well.
(R) Just going back to that silicosis, so essentially the amount of dust, the more that
you are breathing in the faster you are going to see those particularly health
effects, the shorter the latency period, so once again, coming back to doing as
much as you can to control it as low as reasonably practical. So, it seems that we
are saying, if I can summarise, the health risks I guess associated with crystalline
silica are significantly lowered, the lower the dust that people are breathing in, i.e.
the controls you are putting in.
Episode 5- Kate Cole, Silica - Part 1 12
(C) Yes, so the lower your exposure to silica dust, the less your risk of developing
disease associated with silica exposure. So, less silica dust exposure, less chance
of developing silicosis.
(R) That is part 1 of my conversation with Kate Cole around silica. Make sure you
download the next episode when that is released to listen to part 2 as well. If you
have any questions, comments, suggestions for any future topics or guests you
think we should get into the studio, you can send us an email to
[email protected]. You can also contact us via that email if you need
any help around RPE, respiratory protective equipment, around silica, or any other
PPE, we can come out to your workplace and give you a hand as well. Be sure to
subscribe to the podcast through ITunes or wherever you get this podcast from so
you don’t miss any future podcasts including part 2 of my chat with Kate. If you
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take a few moments to leave us a review as it really does help other people to find
this podcast as well. And, as Willie Nelson once said, “Once you replace negative
thoughts with positive ones you will start having positive results.” Thanks for
listening and have a safe day.