[MUSIC] Good day. My name is Patrick Breysse. I'm a professor in the Department of Environmental Health Sciences at the Johns Hopkins Bloomberg School of Public Health. And I'd like to spend the next 15 minutes or so Ttalking to you about nanotechnology and worker health. Let's start with some definitions, so we're all on the same page. So nanosized particles can either be engineered purposefully or they can occur in the ambient environment either due to some pollution process or some natural process. What they all have in common is that they have a dimension at least one dimension that's less than 100 nanometers in size. And we'll talk about size in more detail in the next couple slides. But we distinguish between particles that are engineered to be nanoscale purposefully, and we call those engineered nanoparticles. And the nanosized particles are specifically engineered, like I said, either in a lab or in a manufacturing environment to have specific properties and these properties take advantage of their nanoscale to enhance mechanical, electrical, optical, catalytic, biological or other activities. So, these are partials that are purposely made small and they're made purposely with some sort of enhanced property that they can take advantage of at the nanoscale. Examples are metal oxides, carbon nanotubes, quantum dots. We'll talk more about some of these nanoparticles and what some of their applications are in subsequent slides. But we distinguish between particles that occur in the environment that are not purposefully made and these are usually called, if you look at the environmental literature, they'll be called ultrafine particles. So in the ambient air, we talk about coarse particles, fine particles, and ultrafine particles. Ultrafine particles are also nanoscale particles. But they're not produced in a controlled, engineered way. An example of these are diesel particles have nanoparticles, other combustion environment, so cigarette smoke gives off particles in the nanosize range. And so the literature talks about ultrafine particles and they distinguish them between engineered nanoparticles and because it is just how they're made. And the engineered particles have very specific properties that are tailored to the application that they're made. And sometimes that can lead to very specific potential toxicities that would be of concern to us in a workplace environment. So let's talk about size. So size on this scale is often hard for people to think about. And so, what we have in the top panel of this graph, is a example of a nanoparticle called the, single-walled carbon nanotube. And it has this one dimension, the diameter of the particle is one nanometer in diameter, so it's very, very small. And it could be hundreds of nanometers long, but that one dimension is really makes it kind of special. And so just to kind of put it in contrast, so if we multiply that carbon nanotube by 100,000, we get something that's about the size of a human hair and a human hair is a 100 micrometers in diameter. If we multiply the human hair by 100,000 we get something that's about the size of a house about ten meters wide. So now you kind of see, that's a pretty narrow house maybe that's a row house here in Baltimore, but now you kind of see the scale of things. So we're really talking about stuff that's very, very small. And to place it in perspective for something that's not a long thin fiber, we have a nanoparticle, the bottom that's cuboid shaped. It's four micrometers in diameter. If we multiply that by a million, we get the size of an ant. If we multiply that by a million, we get the size of the Indianapolis Motor Speedway. So, we're talking about things to scale here, it's almost hard to comprehend. And it's really the advent of modern technology that allows us now to make things this small, and manipulate properties of matter at this scale. Now, it's very exciting, because these properties may have us do things with nanoparticles that can enhance our ability to treat disease, it could enhance our ability to clean up the environment, it could make bulletproof vests. But now we have to think about also, are we introducing unique toxicities with all these unique properties that we're taking advantage of? So nanoparticles as I've alluded to have many uses. And I just list some of them here. There are websites that pages and pages, hundreds of pages of nanoparticles and their different uses. And it's expanding, it's getting more and more every day. So some things we're probably pretty familiar with but you don't think about are metal oxides. So nano metal oxides are used in something that probably everybody is familiar with, sunscreens. So they have zinc oxide in them. Now in the old days when they'd make sunscreen with zinc oxide and they used particles that were micron sized, not nano sized. When you put it on the nose, where everybody remembers seeing the lifeguard with the big white nose, right? That's because those particles were big. Once they made them nano sized, it became clear. And so now when people put zinc oxide or sunscreens with zinc oxide and they're not all white. And so obviously people like that better. But nano metal oxides are in many consumer products including cosmetics, sunscreen I mentioned, it's used for electronics, there's bio-medical examples, there's nano metal oxides used for catalysts for environmental remediation, so there's lots of applications. Carbon nanotubes are also very exciting, because they can be woven into textiles, they can be used in bullet-proof vests and other kind of structurally resistant clothing. So there's lots of products that take advantage of the unique properties of carbon nanotubes. Quantum dots are very specific particles that have optical properties that can be beneficial. And so they can be used in electrical applications, modern screens, LEDs, flexible screens, imaging devices can take advantage of quantum dots. Buckyballs are the small nanoparticles made up entirely of carbon that can be used as lubricants, superconductors, or used as solar cells. You know, something we've eluded to, that the properties in nanomaterials are special. And let's just kind of touch on them briefly. So nanomaterials can be made to be more chemically reactive. We know that their properties such as their solubility, their size and their charge can influence biological activity. Their unique sizes can also mimic biological molecules. So to make them interesting in biomedical applications. It could also make them problematic from a health standpoint. We know that their small size allows them to enter cells and cell organelles and they can be more readily transported in air and water. So all these things make us kind of happy about kind of their applications, but also makes us kind of concerned about what the potential health effects are. So we can engineer something to get into a cell for medical purposes, but maybe not all applications are medical. So we can get into a cell on one hand and be good. On the other hand, if it gets into a cell, it might have a health effect that we're worried about. So one of the areas that creates the most concern is that if you make particles smaller and smaller, and smaller you increase their surface area. And if there's a biological reactivity associated with the particle, the more surface area it has maybe the more biologically active it's going to be. And so, this cartoon here illustrates that just beautifully, so on the left hand side of the cartoon you see a cube that's one cm by one cm. So the total surface area of that cube is six square centimeters. Now imagine we take that cube and we break it up into cubes that are one millimeter on each side. And so now, if broke that up, and you see that in the picture, and we spread it all out, we would have 60 square centimeters. So we went from six square centimeters now to 60 square centimeters of surface area. With the same amount of material. Now imagine we made each size one nanometer. So now we went to 60 million square centimeters. So we took the same material, and the same mass of material, but we created 60 million square centimeters of surface area. Potentially to be interacting with biological molecules, or cells, or other systems that might perturb health or damage the environment. So if surface area's an important predictor, then one of the things that's special about nanometres is they have a huge surface area to mass ratio and that's illustrated nicely in this slide. Now unfortunately there's little information about the hazards of nanomaterials and the health effects of nanoparticles. But the concerns include people who use them and work with them may inhale them. They can ingest them or they can get them on their skin. In some cases, they're small enough to go through the skin or maybe if you have cuts and sores, they could enter your body through the cuts and sores. There's lots of agencies in the United States including OSHA, the Occupational Safety and Health Administration. NIOSH, the National Institute Of Safety and Health. The EPA, the Environmental Protection Agency. Are actively working on how to figure out how to protect workers in the environment for these materials. So there's a lot of concerns at regulatory and research agencies at national, international levels. OSHA for example, like I said, OSHA is the Occupational Safety Health Administration currently does not have any occupational exposure limits for nanomaterials. A lot of things you work with OSHA says how much you can be expose to at a safe level, they're not quite there yet with nanomaterials and that's because the evidence base there to set those standards does not exist. And of course the standards can vary depending on, not only whether it's a nanomaterial or not, but what the material's made out of. Right? So a carbon nanotube could have a different biological activity than a metal oxide, for example, a nano metal oxide. So the most common routes of exposure for anything in the environment, not just nanomaterials are inhalation, ingestion, and through the skin. And we know that for again, in generic sense, exposure factors that help us define kind of when we're concerned about something deal with the concentration or amount of stuff that's entering the body through one of these routes. The duration that it's entering the body or the frequency that you come in contact with it. So how much you're exposed to, how long you're exposed to it and how often you're exposed to, are all determinants of what it means to be exposed. And this applies to nanomaterials or anything actually in the workplace or the general environment. But the opportunities for exposure, for handling nanomaterials are varied, just like with any materials. The industrial processes have many different unit operations, and those unit operations have very specific opportunities for exposure. But in general, when we have to handle powders, dry materials things are more readily kind of aerosolized, you inhale them. When you work with liquid media, liquid media can be got on the skin, it can be ingested if it gets on your skin depending on how you're handling liquid media, you can create small particles out of the handling. We know that there are open systems in industrial processes that mix things, and when you mix things in open systems there's opportunity for these to get into the air. We also know that for any industrial process, if you have maintenance activities, those are opportunities for exposure as well. So maintenance on equipment and processes use fabrication also presents important opportunities for exposure. So when you think broadly about kind of how people are using nano materials and what the opportunities for exposures are, and thinking about how do we characterize them. Now, the traditional occupational hygiene approach to assessing the worker's exposure is as follows. I would come into the workplace and I know something about the toxicity of the substance I'm interested in, and I collect an air sample. And for most things in the workplace, there's standard air sample methods that we could use. We collect the air sample, we bring it back, we analyze it for the contaminant of interest, we compare the concentration in it to an exposure limit and we make a judgement about whether it's too high or not. And based on whether it is too high or not, we design a control method to lower the exposure into something we consider acceptable. The challenge with nanomaterials is we don't have good error sampling methods. We don't have good analytical methods for these materials because they are new, right? And we don't have exposure limits. So there's a lot of gaps here in our ability to kind of protect the worker. And in fact, measuring and characterizing an exposure is something that's very difficult to do. Many of the occupational hygiene methods that we use are relatively straight forward. Lots of people trained on how to use them, that's not the case however for nanoparticles. So the problems with the traditional approach as I mentioned are that nanoparticles can vary greatly in terms of their composition, size, and physical chemical properties. So we're talking about nanoparticles in this course kind of simplistically as if it's all one thing but recognize it's thousands of things. There's no valid sampling and local methods for these nanoparticles, and occupational exposure standards or guidelines don't exist. So these create huge challenges now for protecting workers. So again, the traditional approach to controlling things in the workplace are, you see an inverted triangle here, and the first thing you want to do, and the invert tracker suggests that the things at the top are higher priority. And the things at the bottom are your last priority in terms of options for protecting workers. So, the first thing you'll like to do is, if possibly, you want to eliminate a hazardous substance from a working environment. And if there's a non-toxic alternate, you'd want to switch to that. If you can't eliminate or substitute it, you want to have engineering controls that stop the exposure from occurring. And if you can't do that, you want to have administrative controls, that kind of limit your exposure around the material. Or control how you use it so it do not release as much. And lastly, you want to put person protector equipment on the worker like a respirator. Now sometimes you use a combination of these things. But the philosophy here is that you want to start with things at the top of the triangle here at the base, the flat part, and your last options are the things towards the bottom. And this applies to nanomaterials or non-nanomaterials. What this really says is we need to think about engineering controls as the primary way to control the workplace when nanomaterials are present. What that means is we want to make sure that the sources are enclosed wherever it's possible. We need to make sure that local exhaust ventilation is used to collect the particles that they are being released. We make sure that high-efficiency particulate air filters are used to kind of collect the particles. We still want to rely on personal protective equipment in terms of gloves and lab coats to stop things from getting on our bodies. But would probably want to use respirator as a last resort if these injury controls are not sufficient. Now there are guidelines for disposal of hazardous materials that industries have to comply with. But just like with the guidelines for worker exposures, there are currently no specific EPA regulations or guidelines for the proper disposal of nanomaterials. But I think it's prudent to kind of treat them as hazardous materials nonetheless. And so that we suggest that contaminated materials, materials that are contaminated with nanoparticles or nanomaterials and waste products, should be collected in leak-tight polyethylene bags and treated as solid wastes. Pure nanomaterials in solid or powder form should be containerized and submitted as hazardous wastes. Nanomaterials dissolved in solvents or in formulations that are liquid media should be collected and submitted as hazardous wastes and mixtures. And so we think it's prudent to treat nanomaterials as if they're hazardous materials and dispose of them in the same manner. So in summary, we've talked about a variety of topics in this short discussion. But we wanted to emphasize that nanoparticles are very small. We talked about what it means to be small. So nanoscale particles, and they have unique properties that are special, or nanoscale, and that means they behave differently than more regular shaped particles, or particles that we more commonly encounter which are more in the micron scale, rather than nanometer scale. They're everywhere, they're in the ambient environment, and they're also in engineered nanoparticles are in many consumer products. We know very little about their health effects. And unfortunately there's little guidance about how to handle them safely. But, there are prudent approaches we can take, and we discussed some of them. So thank you very much for your time, cheers. [MUSIC]
