Return to audio interviewPrevious episodeNext episode | Explore UC Science Radio
Molly Magid: Welcome to UC Science Radio, where we conduct interviews with a range of scientists to learn about the big issues facing our world and what science is doing to help. I'm Molly Magid, a master’s student in the School of Biological Sciences.
Today I’m talking with Dr. Sally Gaw. She’s an environmental chemist, Associate Professor in chemistry, and the Director of Environmental Science at UC. Her research focuses on contaminants in the environment. Sally is passionate about creating evidence-based policy to protect the health of the environment, organisms, and people of New Zealand.
Kia ora Sally, thanks for coming on UC Science Radio! I'm interested in what your role is at UC and what your research is on.
Sally Gaw: Thank you for the invitation. I'm an environmental chemist, and I'm employed in the College of Science. I teach in the Chemistry programme which is in my home school, the School of Physical and Chemical Sciences. But I'm am also the Director of Environmental Science, which is run out of the School of Earth and Environment. So I work across the university. I have taught programs in Engineering, I have taught in programs across Science: Chemistry courses, some of the Antarctic courses, the Water Resource Management courses, the Environmental Science courses. My expertise and interest is in understanding where chemicals come from and where they might go, and what kind of impacts they might have.
I'm particularly interested in understanding how our everyday lives contribute to environmental contamination. We sort of have that idea that there is contamination in the environment and it's got nothing to do with us. You know, it's industry, it's farming, it's someone else. But in actual fact, many of the reasons that we have environmental contamination is because of goods or activities occurring, that benefit our everyday lives. So I'm interested in that space.
So where are these chemicals coming from and how are they getting into water streams?
:We have resources come into our cities and we use them in some way. That can be water coming in, that can be energy coming in to keep our houses warm and keep our lights on, it's the clothing and things that we import. So we have a whole lot of resources and things that we need to lead the lives that we lead. As we use them and as we do things with them, either during the processing and the manufacturing of those resources, or the gathering of those resources, or as we use them, or at the end of their life, environmental contamination will occur.
If you think about, for example, something that probably everybody's used today, is soap. There will have been contaminants or environmental issues created during the production of that soap. We then use it in our house. Depending on what's in that soap, we then use it on our clothes or we might use it on our bodies, we wash something with it, and residues then end up in wastewater, which ends up in the sewers, which then ends up in a wastewater treatment plant. If there's something in that soap that the wastewater treatment plant is not able to process or remove, then that will end up either in the biosolids, the solids that are left over after wastewater treatment, which is often used as a resource somewhere else in the environment, or in the water that is released from the wastewater treatment plant. If along the way, we actually use that soap outside and we use it to wash our cars, then that could then run off the car and onto the road and then end up in storm water and here in Christchurch end up in one of our streams and ultimately out in the ocean, out in the estuaries, out in the harbor, somewhere like that. Or if we have something that is collected and ends up in a wastewater treatment plant, or should end up in a wastewater treatment plant, but there's a break somewhere in the pipes, then that can also be released into the environment.
What sorts of issues happen when chemicals like that end up in the ocean or in streams?
:Well, there's a range of different issues that can happen. I'm interested in a class that's called emerging contaminants, so that's contaminants that we're starting to think "hmmm, we need to think about those." Sometimes it means we can actually measure them in the environment, or we know something about their toxicity. I'm interested in the contaminants that we don't know very much about, and so we may not know the effects that they might have. Or we know that they might impact on aquatic organisms in some way, that they may be toxic, they may accumulate in sediments, some of the chemicals that they break down into may be more toxic than where we even started from. One of the other contaminants that I'm working on in that space is microplastics, from when we release plastic out into the environment. And that often can be used in personal care products, though that is increasingly being controlled.
Are there things that individuals can do to limit the chemicals that they put out, or is it a thing that industries or the government has to change in terms of banning the use of certain chemicals?
:I think it's a multiple approach. So if you think of something like microbeads, which were in personal care products, they were used as skin exfoliants, they've been removed. Now, they were ultimately removed because the government brought in some legislation to say we wouldn't have them anymore, but there was consumer pressure. There was some good research done in universities that said we have these here. Some of the work we've been doing found microbeads out in the environment, which is very exciting, for us, not for the environment. So there were people saying we're not happy about this, we're not comfortable about this, and then the government picks it up as an issue and says: "Well actually we're not going to do that anymore." It's sort of a two-way thing, you have regulation but often you need the science and the information to say there might be a problem, you need enough of a community concern or a reason to say: "Hey we'd actually really like this to be re-looked at, so we'd like our regulatory agencies to have another look at it." Ultimately you need the government to make the rules to say we aren't going to do that anymore.
Now that's something that I think we need to improve on in New Zealand, is understanding what chemicals come into New سԹin products. We're very good at regulating and managing chemicals that come in as a chemical. If it comes in a drum or comes in a bucket and is labelled as a chemical, then it is well-regulated. We don't have so much information about what comes into New سԹas something that is manufactured. If you think about your sofa or your car or your computer, there's actually quite a lot of chemicals in there that are used to produce that, and we don't have a good handle on what they are or what quantities there are.
You mentioned a little bit about microplastics, could you explain what microplastics are and how they form?
SG: Sure, microplastics are small items of plastic that are less than, we'll say 5 mm, there's some variation in what different definitions are. So they're less than 5 mm in diameter. They can be primary microplastics, those are microplastics that are produced as microplastics. They might have been exfoliants that may be used in skin care products, they might be used in air blasting or spray blasting for sort of industrial applications, or they may even be the pellets that are used. Most of the plastic that comes into New سԹcome in these small plastic pellets, small plastic beads, and they get melted down and then they get made into lunch boxes and drink bottles, and whatever we make into plastic. So those are the primary microplastics. Those are easier to control.
Then we have the secondary microplastics and these will be a nightmare to control. These are the small pieces of plastic that are produced from the breakdown of larger plastic items. Tyres on the road will produce microplastics. Litter that gets released into the environment will break down and form microplastics. Another form of these are the microfibers that are produced when we wash clothing made of synthetic materials, so, nylon, polyester, polypropolene. These are produced in the environment either by physical breaking down processes, or sunlight. If you think you've got something sitting on the beach being dragged up and down the beach in the sand, then that will also cause more bits to shave off.
I think people are used to thinking of like trash in the ocean as big pieces of plastic that maybe get stuck around an animal's neck or in their nostril or something like that, and that's clearly harmful, but what do these microplastics do when wildlife interact with them?
SG: You're right, there's a very lot of plastic there that's not easy to see until you start looking for it. And you can be surprised. I've looked at the beach and then you think well I've seen a couple bits, and then my students process them and you find out there's actually a lot more there than you thought. One of the problems is that for many organisms these can look like food. Or for organisms that are filter feeders, so the way they feed is they suck water through and they take out the big bits and they break them down. When they get these plastic bits inside them, it can do them some damage. They might be a bit abrasive, or they might cut them in some way or do something. The other problem is they give a false feeling of being full because their stomachs or their gastrointestinal tracts are now lined chockablock with these small bits of plastic, so then they're not feeding. Then they lose body condition, they're not getting nutrients, they can't grow, they can't reproduce, so that's one of the concerns.
The other problem is that plastics aren't always very benign. When we make a lot of plastic items, we often have chemical additives added to them. There is some concern that those chemical additives may be toxic. So not all plastic is like what you'd expect in your lunchbox and it's food safe, there are other things in there. I've got my computer sitting on my knee while I'm talking to you. There's going to be a whole lot of flame retardants, there's going be other additives in there that are going stop the plastic breaking down and my computer staying like a computer. There is concern about when those plastics get out in the environment, then those chemicals leach out into the organisms. Finally, there's starting being concern about the really, really small plastics and whether they can cross barriers across cell lines and move around inside an organism, causing damage as they do so.
Is there a human health concern around eating those creatures that may have ingested plastic?
:At the moment, I think that's a big question mark and people are still working through, and I'm involved in a couple of projects that will be looking at that space. We are exposed to so much plastic in our everyday lives: most people use a plastic toothbrush, we drink out of plastic containers, people probably chew on their pens while they're thinking. There's so much plastic, it's really hard to tell. There's an interesting Irish study where they created meals that had seafood in them and they compared the microplastics that were just in the meal versus if you left the meal out in the time that someone would be eating, what came out of the house and added to it. And they found that there was a much, much bigger exposure from sort of the dust and things in the house while you were eating the meal than there was just from the seafood component. So this is really a space where there's a big question mark.
You were talking about all the products that are made of plastic or have plastic in them, why is plastic used so much in our products?
SG: Well it is a bit of a wonder material-- it's very strong, it's lightweight, there are some advantages in using it as a packaging material because it's waterproof, in some cases it will keep food safer for longer. By having lighter packaging compared to having glass bottles for milk, there's some gains in terms of energy, in terms of transport because it's not as heavy. There are many, many advantages to plastic. But one of the problems is we're quite often using a very permanent material for very short-term uses. These single-use plastics I think are one of the first things we need to think about. We're talking about very permanent materials that will last for a very, very long time and we often use them for less than half an hour.
I think that part of our problem is that we are using plastic so indiscriminately and we're using so much of it. We've done this with all sorts of other materials and other products through time, of working out, well this is a really great material but we're only going to use it for these uses. When we do that, we're going to use it in certain ways so we can recycle it or reuse it more easily. One of the things that limits recycling at the moment is that some plastics are more difficult than others to recycle, and it's definitely difficult to recycle things when plastic items are made out of two or three different kinds of plastic. If you look at a drink bottle or many, many other things that are made out of plastic, you'll actually see that there's actually two or three different kinds of plastic there. And that becomes a problem for recycling because sometimes you just can't melt the whole lot down, because when you try to do that you're only going to make a mess because those three plastics are not going melt together.
I know there was a plastic bag ban that started in July of last year - do you think things like that are helping to reduce plastic use?
SG: I think so, and they're also getting people to think about: "Do I really need something that's single-use?" It’s been quite useful to actually think about what is an appropriate use. Plastic was making up quite a significant proportion of our landfills. It's a very lightweight material, and it's very tricky to manage in a landfill setting, because particularly plastic bags and things like that because they can blow away. Anything where people start thinking about single-use plastics and designing them out, is a really good idea. There's also other benefits: the amount of energy that goes into making plastics, then you've got to deal with them when you throw them out, and you got to deal with them forever.
I'm also thinking about plastic novelty items and plastic giveaways and things. You know, plastic Happy Meal toys and those sorts of things. Really thinking about whether that is an appropriate use, and I think it's going to come down to some conversations as a community of what is a good use of plastic, what is a frivolous use of plastic, and what is an appropriate use of this material. Because it is a valuable and useful material. I'm quite happy that whenever I have a medical procedure, that the syringes that are used on me are single-use plastic. That I think is an important use. Whether having a plastic lid on a takeaway coffee cup is a good use or not is something that we need to talk about.
Something I've been thinking about during this time is the use of things like anti-microbial or anti-bacterial soap which people may be using potentially at a higher rate during a time of pandemic. First of all, what harm can antibacterials or anti-microbials do if they end up in the rivers or in the ocean? And then second, how is there a balance between people trying to think about their health and preserving the environment?
:The first thing I want to say is that the available evidence is that in controlling disease at home, ordinary soap and water is as good as anti-microbial compounds. That's the evidence that is out there. Now whether that applies for the particular virus we're talking about now, I don't think anybody knows. But the evidence says good washing and drying your hands properly, and the drying is really important, is as good. There have been some studies done looking at in non-clinical settings, at home, how well do they work.
Antimicrobial compounds are problematic for a few reasons. One, when they go out into the environment, they're anti-microbial so they work on microbial things. Anti-microbials such as triclosan and some others have been shown to impact on algae, which are the primary producers. They are the little engines at the bottom of the food chain that collect all the energy from the sun, they are photosynthetic organisms. They produce the food for everybody else.
They're the harvesters of the energy and they are the primary producers. There is evidence anti-microbial compounds would change how much you have, which organisms you have, and so could potentially have a lot of impacts on food chains.
The other problem with anti-microbial compounds is that we're getting problems with anti-microbial resistance. That’s bacteria becoming resistant to pharmaceuticals that we'd really rather they didn't. It's been shown that some of the anti-microbial compounds that we can use and that we can use at home would contribute to the development of anti-microbial resistance. So by not using anti-microbial compounds when you don't need to use them actually contributes to protecting your health.
Now the problem with anti-microbial resistance is that one group of bacteria can learn how to develop defense mechanisms for anti-microbials. But what happens is that bacteria have a really nifty trick. And I wish someone could do this for me with calculus, in that they can share genetic material they have. Once they've figured out how to work around an anti-microbial compound, and often that mechanism will be the same they'd use to work around an antibiotic, they can then give that information over to a bacteria that might be able to make us sick, so a pathogenic bacteria. We need to be a little bit careful about anti-microbials that we're using them in the right way, and we're not making things worse for ourselves.
So that's why I don't use anti-bacterial or anti-microbial soaps a home because I'm concerned about the human health impacts of some of those. I'm the one that shouts at the television at home when you see, you know, they have the stereotype of the mother cleaning the kitchen with an anti-microbial wipe and she's protecting her family. In actual fact, that may not be protecting her family that actually may be something that could in the long run cause more harm.
So backing up a bit, what was your path to this research?
:Well, from about the age of 16, I wanted to be an environmental chemist, so it's just as well that now I've grown up and I am one, that I really love it. I bounced backwards and forwards a wee bit between the University of Auckland and the University of Waikato, ending up with a Master's in Environmental Science and Chemistry, and so I did a project on stormwater. Then I did a little bit of work in consulting firms. I did a little bit of work in a wastewater treatment plant, in their lab, that was an interesting process. Then, I ended up working for the public health service in Aukland, where I was an environmental scientist in a team helping to protect people from environmental hazards. I didn't have the warranted kind of responsibilities that the public health officers did, but I did a lot of work around resource management processes.
At the same time, I was doing my PhD which was looking at contaminated land. I identified a new area of concern for New سԹwhich was our former horticultural land. That was an interesting project to do, it was challenging in many ways because many, many people were not at all happy with the results I was finding. I was very lucky because of where I was, that I got to work with some government agencies, I got to work with regional councils, and that helped sort of build towards the momentum we now have the National Environmental Standards for Contaminated Soil. After I finished my PhD, because of the experience that I'd had, I ended up working for ESR for a while in a similar kind of role, but on a more national role. I wanted to be research-active so I moved to the University about 13 years ago.
It sounds like you've had a lot of experience in different industries and then also in government. How have you found it applying science to people in government or people in industries who may not have the background in science but trying to communicate that and also persuade them that these things are important to think about?
SG: I've been lucky in that there's always been a group of us working on it. I think it's thinking very carefully about what the key messages are. You also need to think about not being necessarily alarmist. The most important part is actually taking some time to think about what it is you need to communicate and how you want to do it, being prepared to listen a lot, to accept that there may be different viewpoints. That is an interesting one and I work through with a lot my students. We provide information to decision makers, we are not necessarily the decision makers, and the decision makers will be balancing a range of interests.
You can see that at the moment with Covid-19, our Prime Minister Jacinda Ardern is trying to balance economic interests, health interests, international things, and there's a whole range of things that are going into some of those decisions. It's the same thing in the environmental science space: we bring in the information. You may have a very strong viewpoint about what’s the best thing to do, but the decision-maker may have to balance competing ideas.
You mentioned trying to keep your language not alarmist but it seems when you learn about these pretty alarming things - the amount of chemicals or plastic that's ending up in the ocean - and things that seem like a big deal. So how do you not engage in that sort of alarmist speak about things that are pretty alarming?
SG: I usually take this approach very carefully when I'm interviewed for media articles and things. There have been a couple of occasions where I have been concerned enough about something, some information that I have been given, that I will go back to the decision-maker or back to someone who's in control of the event if there's been a spill or something and say: "Ok I think you really need to know this piece of information." But I'm not going to go and scare the whole of New سԹor a whole range of communities with it.
There was one recently, there was a warehouse down South that was storing a waste from the smelter. Now that material, it's called ouvea, when that gets wet it generates ammonia. Now in that case, I did say in interviews that this can cause death, because the release of ammonia gas can cause death. In that case, I felt the community did need to know that if there was a gas leak, then they really did need to stay away. It depends on what it is and what the level of hazard is, where my language will be. I don't want to oversell or be the person who cried wolf over something that maybe if we've got longer to work through, we find there's no immediate threat to human health or the environment or ecological receptors, fish, eels.
My last question is, if you could say in one sentence why your work is so important?
:Because I believe in evidence-based policy. When we get treated in the hospital, we expect the doctors are practicing evidence-based medicine - that how they treat us and what they decide to do is based on strong evidence and strong science. I want to see the same for our policy. The decisions that we make about how we protect our environment and how we protect our people in New Zealand, I want to be based on strong science and so I want to contribute to that.
Thank you so much for talking with me!
SG: Well thank you for the opportunity to do this.
Return to audio interviewPrevious episodeNext episode | Explore UC Science Radio
