[MUSIC] Hi, this is Michael Trush, I'm a Professor of Environmental Health Sciences, and I'm going to do a presentation where we look in to the World of Toxicology. This presentation will be divided into two sections. The first to just, the Introduction to Chemicals and Health. Give you perspective about chemical exposures. And then we'll move into some specific processes in section two. I mentioned that we're going to look into the World of Toxicology. You may have heard that word, but, don't know what it actually means in terms of science. Toxicology really means looking as the study of poisons. And in this presentation we're going to define. Poisons as chemical or physical substances, which produce adverse responses or toxicity in biological organisms. So we're all familiar with chemicals, you may not be familiar with physical substances, but these would include things like asbestos fibers, noise. Ultra violet radiation, those are physical substances which actually can produce adverse effects. Now these poisons that we're going to be discussing could actually be divided into two categories. What we call Toxicants and Toxins. Toxicants, are substances that either are made by man. Or come from man's activities such as mining, driving automobiles, things of that nature those of human activities which release things into our environment. Toxins, are substances that can be toxic, but, they're produced by living organisms. These can be reptiles. Such as rattlesnake on this slide, insects, plants and micro-organisms. So, one of the things I will point out to you that if you read the lay literature, that means newspapers or magazine articles, they'll often use the word Toxins. When they really mean Toxicants. So be aware of that. So this field of Toxicology really develop the time in human history, when really humans were using chemicals to poison their enemies. So, you can go back in history if you watch movies. You will see about the food tasters for kings and so forth. You may see movies where various cultures use poison arrows and so forth like that. So this field actually developed about of this, use of various agents to poison enemies. While this led to development of antidotes. So Toxicology really, it's preventive science, and that's why it's really important in the field of public health. So, in general, we start talking about poisons and so forth, coming from chemicals. We need to understand though, we are exposed to chemicals on a daily basis. We eat, we drink, we breathe, and there are chemicals in them. Now amongst these chemicals that we're exposed to on a daily basis, somewhere intended for human administration exposure, or use, that would be our pharmaceuticals. Others are not, those are the environmental chemicals. All chemicals are potentially Toxic. What makes something Toxic, is the dose. And really the father of Toxicology, really came up with the phrase the dose makes the poison. There are some chemicals out there that are extremely Toxic, that includes bocholinim toxic or Botox. Which is the most toxic molecule, on the planet. And then, we can even talk about sugar being toxic, but it's dose is very, very high. Where there's probably no chance of ever experiencing toxicity, from it. We also have appreciate that, there are variations in response to chemicals. So, if you take the human population given. Equal exposures to various chemicals. There will be variations we refer to this generally as susceptibility. These variations are in fact due to genetics. Because we're not all, genetically similar. And also the age of exposure. Whether you be a young child, or an adult. The age of exposure, in response to chemicals is very, very different. What we're starting learning now, that even, there's a lot of exposure to the fetus in utero, to chemicals which are potentially toxic. If you take a umbilical cord and you analyze it, you'll find anywhere from 200 to 300. Potentially toxic chemicals that that fetus has been exposed to during its development. So, those are some general concepts, so let's talk a little bit more about, Environmental Chemicals. So, mentioned originally Toxicology, came from this idea of poisoning enemies. As man developed, we went into the industrial revolution and as we went into the. Industrial Revolution. We started using chemicals more in manufacturing, and so forth. And really are concerned for Environmental Chemicals, originated from occupational exposures. We started seeing worker populations where there were high exposures, coming down with certain diseases. In fact, most of what we know about. Chemicals in cancer, originate from these occupational exposures. During mans' time, we've increased production of synthetic organic chemicals. The chemists have really been busy making all kinds of things, dyes, plastics, solvents, mostly for human use. There are approximately now 100,000 synthetic chemicals, on the global market. Many of these, we have very little information about their potential human toxicity. Many other chemicals are emitted as either the by-products, of their use or disposal. One of the biggest problems we have, is how do we dispose of industrial waste? And, that really leads to a lot of human exposure. Exposure can also occur as a result, of industrial accidents. One of the most famous accidents happened in Bhopal, India. Where a chemical plant had an explosion. A gas is released and there are 15,000 deaths that occurred there. So, there are number of ways we can, get exposed to chemicals from the environment. However, well we are concerned about, chemicals from industrial processes, studies have shown that we are exposed. To Many Potential Toxicants actually enter Homes, or many products within our homes which are potentially toxic. So, if you look for example in the living room. You have a sofa that has fabric on it. Often in those fabrics, they put a flame retardant. Flame retardant belonged to a chemical class called BDEs. And we found out that there was human exposure coming into people. This was actually highlighted, this study in Sweden, when they looked at breast milk of mothers and they found this class of chemicals. In their breast milk. This has now led to, reduction in this class of chemicals. We're concerned about them, we found, because we found out in animals they affect organ development. So, these PBDEs are found in foam mattresses, carpets, padding and electronics. If you move into the bathroom, for example, you may have a plastic shower curtain. On that plastic shower curtain, are a group of chemicals called Phthalates. They're added to the shower curtain, to make that plastic flexible. Or if you're take your shampoo bottle, and look on it. Make that plastic a little bit more flexible there may be Phthalates in it. We know that Phthalates cause developmental problems, in male reproductive track. And this can result in immunal exposures. Move to the kitchen, a food can as you open it, you may see that little white lining in there. That white lining contains what are called Bisphenols. And there's concern that over time Bisphenols, leak out of the can into the product. Way in we know that Bisphenols expose, affect responses to hormones. In fact chemicals which affect development, or hormone responses are often referred to as endocrine disruptors. Also within the house, depending upon if your house was built before 1958. You still may have lead paint in your house. Where if you built your house, in a certain areas of the country, the basement may have radon gas, which is a leading cause of lung cancer. So there are a lot of potential exposures, in our homes that we need to be aware of. Now, earlier I mentioned that there are chemicals where we develop for human use, and those are pharmaceutical agents. Pharmaceutical agents are not without toxicity. The one difference between pharmaceutical agents, and Environmental Chemicals. Is that pharmaceutical agents undergo much more, toxicity testing it includes in humans. Because they're intended for human use, so the original studies are done in animals just like Environmental Chemicals. But then pharmaceutical agents, drugs. Go through clinical trials. However, even after that drugs gone through these clinical trials, and has been approved for human use often times as the drug gets out into the population numbers increase, we often see toxicities incurring in the general population. It's estimated that there. There's something like 2 million patients affected yearly, by pharmaceutical aids leading to many many deaths. The most common cause of liver toxicity or failure in both the US and the UK, is acetaminophen or as we know it, Tylenol. Now, I will say that acetaminophen or Tylenol. Is a very safe drug. If you take it as recommended. However, many people don't take more of it than they should, and result in liver toxicity. That's really the cause of it. Also people will take after they have been drinking chronically. And there's an interaction between, acetaminophen and alcohol. The alcohol, exposure predisposes us to acetaminophen toxicity. Okay, so that concludes the first section where I've tried to give you a brief overview of Chemical exposures, someone with key principles of toxicology, what toxicology is. So, let's now move on to what process are involved in chemical toxicity.
