Chem1a PDF

chem1a Transcribed by TurboScribe.ai. Go Unlimited to remove this message. If I can share the presentation. Okay, are you able to see the slideshow? I can't see the slideshow. Okay, so we are starting a bit later, but it's really a very short introduction to chemicals as a risk factor this afternoo...

chem1a Transcribed by TurboScribe.ai. Go Unlimited to remove this message. If I can share the presentation. Okay, are you able to see the slideshow? I can't see the slideshow. Okay, so we are starting a bit later, but it's really a very short introduction to chemicals as a risk factor this afternoon, and then we'll go into the different aspects related to chemical hazards at work in more detail in the coming weeks. And hopefully we'll get in one or two experts in the field to provide some practical examples of how they manage chemical hazards at work in their respective environments. Okay, so why is chemical risk factors in the workplace a concern? It's estimated that globally over one billion workers are exposed to chemical hazardous substances. Not very good data from the Sub-Saharan African region, but on the WHO website, and this is data from 2017, they don't even have more up-to-date information. They estimated that over 280 million tonnes of industrial chemicals were produced in that year, and of this amount, 28% of 75 million tonnes were hazardous to the environment, and even though at about three-quarters, over 200 million tonnes were hazardous to health. And what we do know is that workers in low and middle-income countries are particularly exposed due to less stringent health and safety regulations, and also inadequate enforcement. Chemical hazards is a very big module, it's a very big block, and it's definitely a real concern in the workplace, especially in our setting. So let's begin by exploring what a chemical is, and just cover a few basics. A chemical is any substance composed of matter that has a definite chemical composition and distinct properties. In essence, chemicals are all around us, and they are the building blocks of matter. Chemicals can exist in various forms, in elements, compounds, or mixtures. So elements are the pure substances consisting of only one type of atom. Examples include hydrogen, oxygen, iron, and elements cannot be broken down into more basic substances by chemical means. Compounds are substances formed when two or more elements are combined or chemically bonded in fixed proportions. So an example of a compound would be water, or H2O, carbon dioxide, CO2, and sodium chloride, table salt. These are very common examples of elements. And compounds have properties that are different from the individual elements that compose them. And mixtures are combinations of two or more substances, where each retains its individual chemical properties. So an example could include air or seawater. So air is a mixture of gases, predominantly nitrogen and oxygen, and seawater is water with dissolved salts. And mixtures can often be separated into their respective components by physical means. When we talk about chemicals, we broadly classify chemicals into two distinct categories, organic chemicals and inorganic chemicals. And this is quite important when doing the risk assessment. So organic chemicals are compounds mainly comprised of carbon atoms bonded with hydrogen, oxygen, nitrogen, and other elements. Examples would include methane and benzene. And organic chemicals are widely found in industry. So examples would include fuels, plastics, pharmaceuticals, and various other chemical compounds. Inorganic chemicals are compounds that are not based on carbon-hydrogen bonds. An example would include ammonia, sodium chloride. And inorganic chemicals in industry are using fertilisers, catalysts, and various other industrial processes. And the next step is to understand the properties of chemicals. And understanding the properties of chemicals is important for safe handling and use of chemicals. So we consider both the physical properties and the chemical properties. Physical properties are characteristics observed without changing the chemical's identity. So an example would include the melting point, the boiling point, the state of matters, whether it's a solid, liquid, or gas, and density of the chemical, the colour. So these physical properties help us understand how a chemical behaves under different conditions. The other hand, chemical properties describe the substance's ability to undergo different chemical changes. So examples would include an acid or base reactivity, flammability of a chemical, and toxicity. The chemical properties help us understand how a chemical interacts with other substances, and the potential hazards that the chemical may pose. So why are we concerned about chemicals? Because chemicals play a very important and different roles across different domains. So in nature, chemicals constitute all of matter. They involve various natural processes. And in the workplace, chemicals are essentially every manufacturing process. You can think of pharmaceuticals, agriculture. Think of some of the workplaces we visited during the contact week. And if you didn't come across any chemical hazards in your risk assessment, in your visit, then make a note in the chat and let us know. But I suspect that everyone came across at least one chemical hazard during their visit. And then in daily life, try and go through your day and be mindful for the rest of the day. Look out for how many chemicals you use around the house and at work. So cleaning agents, cosmetics, medications, fuel, all of these impact on health, hygiene, nutrition, and of course they impact employees in the workplace. So then it's very important to understand the safety considerations related to chemicals. We need to understand the regulations and standards governing chemical use and also the environmental impact associated with the chemical supply chain. So from the basic building blocks to chemical use to waste disposal. Let's focus on the workplace. The workplace chemical hazard is any chemical substance present in the work environment that has the potential to cause harm to workers' health or safety. These chemical hazards can pose physical, health, or environmental risks and they can be inhaled, ingested, or come into contact with the skin or eyes. Chemical hazards exist in various forms. Liquid, solid, gases, vapours, fumes, dust, and lint. And you need to be able to differentiate and define these forms and this will be asked in your exams. Okay, so let's go through the different definitions quickly. So a liquid is a state of matter characterised by a definite volume but no fixed shape. So we know liquid flows freely and takes the shape of the container. So in the workplace liquids can pose risks through spills, splashes onto skin or eyes, or inhalation of vapours they emit. Examples of liquids in the workplace could be our organic solvents like benzene or toluene, acids and bases, and then various oils and fuels. Solids are a state of matter with a definite shape and volume. Solids with particles are closely packed and have limited movement. In the work environment, solid chemicals can be hazardous if the chemical itself is inherently toxic, if it's reactive, if it's combustible, or importantly, if it can generate dust. Examples of solid hazardous chemicals could include metals such as lead or mercury, crystalline materials such as silica and asbestos, and pesticides if found in a solid formulation such as granules. Gases, gases are states of matter without a definite shape or volume. They expand to fill the container, which if they are confined into a container and can spread easily through air. So in the workplace, gases can be toxic, flammable, or they can have asphyxiant properties and they may impose inhalation risks. For example, could include our toxic gases that include carbon monoxide, chlorine gas, flammable gas, could be a gas such as hydrogen or methane, and asphyxiant would include nitrogen or helium. And confined spaces would be an important consideration when asphyxiating a potentially asphyxiant gas. So carbon, solids, liquids, and gases. Let's look at what happens when... So we'll start with vapours. So a vapour is when a solid or liquid exists, when a substance exists as a solid or liquid, it can also be found in a gaseous state. And the gaseous state is formed by evaporation or sublimation. Sublimation is the conversion of a substance from a solid to a gaseous state without its becoming liquid. And an example of sublimation could be elemental mercury when it's formed at room temperature. So in the workplace, the vapours are an inhalational hazard, they can be flammable, or they can pose an explosive risk. So some examples of solvent vapours are paints or degreasers, fuel vapours, and as I've mentioned, mercury vapour. Next we look at fumes. So fumes are fine, solid particles suspended in air and they're created when a solid material is vaporised. So it moves from a solid state to a gaseous state by high heat. In the work process, an example could be welding. And then it condenses into very, very tiny, small particles. So in the workplace, fumes can be toxic if inhaled, and commonly they contain metals. So an example could be welding fumes, soldering fumes, or metal casting fumes. Next, dust or solid particles generated by mechanical action, such as cutting, crushing, grinding, drilling, or sanding of solid materials. Dust is mainly an inhalational hazard, and it is responsible for many occupational respiratory diseases, but it can also cause skin irritation, and certain dust can be combustible. Examples include silica dust, wood dust, and coal dust. And then lastly, we consider mists. So mists are tiny liquid droplets suspended in air, and they're formed by condensation of vapour over the dispersion of the liquid through spraying, splashing, or buzzing. So mists are an inhalational risk. They can also come into contact with the skin and eyes, and possibly cause irritation, sensitisation, or other health effects. So examples could include acid mists, oil mists, and pesticide sprays. So it's very important to understand and be able to differentiate the different forms or states of matter, liquid, solid, gases, vapours, fumes, dust, and mists, in order to comprehensively identify and address chemical hazards in the workplace. And only by doing so can you implement appropriate control measures. Is there a question? Okay. Okay, so let me move on to hazardous characteristics of workplace chemical hazards. And we consider the toxicity of the hazard, so the ability of the chemical to cause harmful effects on living organisms. So we have the example of lead or benzene, which could cause poisoning or long-term health issues. The flammability of the chemical hazard, so the potential of the chemical to ignite and cause fire. An example would be solvents like ethanol or acetone, which can easily catch fire if exposed to the ignition source. Corrosiveness of the chemical, so the capacity of the chemical to destroy or damage living tissues or materials on contact. And here we consider our acids, such as sulphuric acid, and even some of the bases, like sodium hydroxide, which can cause severe skin burns. We consider the reactivity, the potency of the chemical to undergo chemical reactions. And as a result, these reactions could release energy or hazardous byproducts. An example could be peroxide. Kaspar Shalit, is that a question? Or is that just a... No, I think that was an accidental... Okay, all right. I just need the news. Thanks. Okay, so then we consider reactivity. So an example of reactive chemicals could be peroxides, which explode under certain conditions or certain metals, which might react with water. We have to consider the carcinogenicity of the chemical. So what is its potential to cause cancer? So it's stochastic effects, and here a classic example might be asbestos fibres, and a number of other chemicals for carcinogenicity or mutagenic effects. And then sensitisation. This is the ability of the chemical to cause allergic reactions. And an example could be isocyanates, which can lead to occupational asthma, and latex proteins, which could cause both either dermatitis or it could also cause occupational asthma. A way to refine chemicals in the workplace. Chemicals can originate from various sources in the work environment. We'll go through a few examples. These could include industrial chemicals, that chemicals could be used in manufacturing, cleaning, or maintenance processes. Pesticides. This could be very relevant to the West and Cape, which is a large employer of agricultural workers. Pesticides are related to anyone employed in an agricultural setting. Pest control. Metals and dust. Generated in mining, construction, and metalworking industries. And then also gases and vapours. So these may be released during chemical reactions or during combustion. So the International Labour Organisation published a review document a few years ago, looking at the global burden of hazardous chemicals in the workplace and the health effects. And they identified the top 10 chemical exposures that needs to be prioritised or concerned. And you can see them listed. I won't go through all of them, but ultimately you'll have to be familiar with each chemical on this list by the end of the module, definitely by graduating. So once we've identified the sources of the hazards, and before looking at the potential health effects, it's important to understand how chemicals enter the body or the routes of exposure. So we'll just recap. We've covered it before. Exposure can occur through inhalation. So breathing in air... Sorry to interrupt you. I just wanted... Someone just noted that we're not recording this session. Is it recording on your side? Because on my side... No, no, no. I haven't... I didn't start recording. Sorry. You can start, Kasper. Do you, Kasper, press record? I did. Thanks, Kasper. Thank you, Kasper. Okay, so we'll start with the routes of exposure. So first we consider inhalation. That's breathing in airborne contaminants, as mentioned. Essentially, all of our states of matter, except the solid chemicals, exposure can occur through inhalation. An example could be inhaling silica dust in construction work, or solvent vapours in painting. Our second route of exposure to consider skin absorption, and we'll cover the mechanism in more detail, in more detail presentation later on, but essentially the chemicals penetrate the skin and enter the systemic circulation. An example could be the absorption of solvents like benzene or pesticides during handling. Also, as you can see in the picture, if there's a break in the integrity of the skin, it can also lead to inadvertent exposure. And ingestion. Ingestion usually occurs accidentally. It's often the unintentional ingestion of chemicals in the work environment. So it could be that someone is working with the substance, they have lunch, and they don't wash their hands, or the eating area is contaminated. But it is an important route of exposure to look out for during the risk assessment process. So, for example, as I've mentioned, consuming food with contaminated hands, and then another consideration could be ingestion of lead particles. Next, we consider injection. We usually think of needlestick injuries in the context of the healthcare environment, but chemical exposure can also occur through puncture wounds. And this could be an accidental needlestick injury, for example, in a laboratory. So I tried to see if this actually happens, and I came across a really interesting case. So I've put the link in the slides, and you can read through the case in your own time. But essentially, it's a consultant in the laboratory who outlines a case where a student working in their lab accidentally injected himself with a few drops of dichloromethane, and it had quite serious consequences. So dichloromethane is a common organic solvent that's used in synthetic chemistry laboratories. So you can see there's the picture of the finger 10 to 15 minutes after the accident on the left. On the right, you can see a picture of the finger. You can see that the puncture had clearly demarcated two hours after the accident. So you can see I took an extract from the article, and the author notes that they left the building and headed to the hospital immediately, which fortunately wasn't in walking distance, and they had a hand trauma unit. And you can see a picture of the finger two hours after the incident with suspected necrosis in the area, and the student said the finger felt quite warm, and they couldn't move the finger at that stage. So I think I'll give you two minutes to read through this very quickly. I'm not going to read through the whole paragraph, but essentially, it outlines the surgeon's assessment, the student's hand surgery, and the surgeon notes that he was concerned that he would have had to amputate at one stage, but they managed to save the finger. So take two minutes, read through the paragraph, and we'll go to the next slide. Okay, so that is included in the slides, and so you can appreciate he managed to save the finger, but he lost the ability to play guitar hero. So you can see the finger on the left at five days after the accident or surgery. The single needle stick injury, but quite a severe consequence, and then quite a good recovery one year after the accident. So it is a route of exposure to go through the injection. And then lastly, we consider eye contact, which would involve chemicals coming into contact with the eyes. This example could be splashes of acids, alkalis, or any other irritating chemical. And then, of course, there's the risk of not only irritation, but of long- term or permanent eye damage. So understanding the routes of exposure is an important part of the risk assessment, and also an important part of implementing effective control measures and preventing exposure. So once we've looked at the source of the chemical and the routes of exposure, we consider the potential health effects. So it says exposure to chemical hazards through the routes I've just outlined can lead to both acute health effects and chronic health effects. And we'll cover this in more detail in a separate lecture, but essentially acute health effects relate to the immediate health impacts, such as burns, irritation, acute asphyxiation. So an example could be a chemical burns from an acid, or possibly immediate loss of consciousness or poisoning from inhaling a toxic gas, or being in a confined space with a noxious gas. And then chronic effects on long-term health issues resulting from prolonged or repeated exposure. So here we consider examples such as silicosis, certain neurological disorders from heavy metal exposure, reproductive problems, and various occupational cancers. And a classic example would be mesothelioma from asbestos exposure. This part of the aisle overview I mentioned earlier, they provide a really nice diagram demonstrating just the different health effects that can occur following exposure to hazardous chemical agents. You can see we have our classic carcinogenic, mutagenic, reproductive toxicity, but essentially chemicals can impact any organ system in the body. So I'll put a link to the document in the bottom, and it's really quite a nice document to read through. And we'll add it to Sunday. It's important to be aware of many different health effects that can occur. Okay, so coming back to our module and sort of our roadmap for the coming week. So the chemical module, as I've mentioned, is a very big module. It's probably the biggest module that you'll complete as part of the diploma. So we're trying to present the work in a structured manner, and we'll be working sequentially through the different aspects related to chemical exposures in the coming weeks, probably until the end of the year. So I've placed this diagram in the WhatsApp group, and if it's useful, you could use it as a study guide, because essentially you will need to know all of the different things that are listed in the diagram. So we'll be covering international conventions. We'll be looking at South African legislation. It might be worthwhile, if you're not from South Africa, going to your own home country and looking at what legislation is in place, what international conventions and regulations have been adopted. We'll also consider standards. We're going to look at the chemical risk assessment process, because that is quite nuanced, and we will also cover principles relevant to toxicology and specific health effects. And if you've had a chance to look at SunLearn, you see that it's quite dense in terms of the coursework that's uploaded. So you'll have to spend some time working through the various chemical categories on SunLearn, FMHS Learn, and this will be self-directed learning. We won't be able to provide a full lecture on each and every type of chemical. We'll try and provide summary lectures, and all of this content will be in your tests and your exams. We will also look at medical surveillance for chemical exposures, and then lastly we'll look at environmental considerations and waste management. So I'm going to spend a few minutes providing a high-level overview of these first few topics of the legislation and standards and guidelines, briefly looking at the chemical hierarchy, and touching on toxicology, and then we'll end for today. Essentially all of these are standalone lectures, so it will be covered in more detail in the coming weeks. Today is just an introduction and a high-level overview. So when you talk about chemical conventions, there are several key international chemical conventions which we need to be aware of. The Baltimore Convention, the Rotterdam, the Stockholm, and the Minamata Convention. Each of these play a specific role in the global management of chemicals. Let's briefly touch on these. We will start with the Basel Convention. It was adopted in 1989 and officially entered into force in 1992. The main objective is to control transboundary movement of hazardous waste and prevent illegal trafficking of chemicals. This file is longer than 30 minutes. Go Unlimited at TurboScribe.ai to transcribe files up to 10 hours long.