Preface

This course is designed for the provider to develop a basic understanding of toxicology. The body can be exposed to a variety of toxins through skin exposure, breathing in toxic substances, and ingesting things that are toxic to them. There are medications that lead to toxicity in excessive amounts and many illicit drugs are actually toxic to the body. There are many environmental toxins people can be exposed to in the environment. Everyone is exposed to some extent to the adverse effects of things like ionizing radiation, workplace toxins, and toxic substances in the environment. At the end of this course, you will understand how and why these things can adversely affect the body.

The focus of chapter one in the course is to discuss the chemistry and toxicity of different inhaled hydrocarbons, including toluene and benzene—both of which are used as solvents in many industries. The inhalation of these substances is a public health crisis because they are found in commonplace items that young people inhale as part of “huffing”. Vinyl chloride is a gas used to make polyvinyl chloride in certain industries and is also toxic at high enough doses. Finally, phenol can be inhaled or ingested and has toxic properties when enough of it is taken in by humans.

Chapter two in the course is about drugs that have known hepatotoxicity and nephrotoxicity. The most commonly used hepatotoxic drug is acetaminophen, which can lead to acute or chronic liver toxicity. There are, on the other hand, many nephrotoxic drugs. The basics of drugs that are nephrotoxic are covered in general, outlining the different drugs and medications that can adversely affect the kidneys. Specific drugs that have known nephrotoxicity include things like lithium, cisplatin, cyclosporine, aminoglycosides, amphotericin B, and NSAIDs. How these drugs are nephrotoxic as well as how toxicities are treated are a part of this chapter.

The main topic of chapter three is heavy metal toxicity. There are several heavy metals that are discussed, including lead toxicity and mercury toxicity, which are relatively common. Toxicity can also exist with arsenic, cadmium, and chromium to a lesser degree. Both children and adults can be exposed to these heavy metals, with effects on

different body areas. The main treatments for heavy metal toxicity of different types are chelation and avoidance of further exposure to the toxic substance.

Chapter four in the course introduces the topic of neurotoxins, which can affect the central nervous system and the peripheral nervous system. The biochemistry of neurotoxins is covered, including the biochemistry of some things talked about in prior chapters as they apply to neurochemistry. Some known neurotoxins, such as shellfish toxins and tetrodotoxin, which comes from pufferfish, are discussed as well as curare, which is a peripheral nervous system neurotoxin that acts on the neuromuscular junction.

Chapter five looks into carcinogenesis and the mechanisms of carcinogenesis. There are many human carcinogens that are classified as being likely or probable carcinogens in the environment. The labeling of something as being carcinogenic depends on which organization is studying these environmental agents. The chapter also covers the different molecular mechanisms by which a given substance is carcinogenic. Tobacco is a common substance that contains many carcinogens within the smoke and tobacco product so this is looked at as a model of something that leads to many different types of cancer in humans.

The focus of chapter six in the course is teratogenesis and teratogens, which are substances, exposures, and infections that can cause birth defects. These include many medications that, if used during certain points in pregnancy, can cause injury or death to the fetus. There are certain drugs that stand out, such as isotretinoin, which is marketed as Accutane, and thalidomide, which led to numerous birth defects in the 1960s. The different categories used to determine risk in pregnancy and lactation are covered in this chapter as well, as these categories can be used by physicians and patients to decide which medications are safe or not safe to take in pregnancy.

Chapter seven in the course discusses the effects of chemicals in the environment that are used to treat things like weeds, agricultural pests, rodents, and even pests that infect humans, like head and body lice. These are chemicals that can be found in residual amounts on agricultural products and other foods that are eaten by the consumer. Individuals who work with these products are also particularly prone to the chemical

toxicity seen with them. The effects of organochlorides like Lindane, used to treat head and body lice, is also covered in this chapter.

The topics included in chapter eight include fungal exposures and the different foodborne toxins that can be gotten from intake of organisms in foods that release toxins. Aflatoxins come from fungal contamination by certain foods, causing various clinical syndromes. Botulism is a severe but uncommon illness that is found when foods are ineffectively preserved. For various reasons, humans can also get Clostridium difficile infections from contaminated food, leading to a toxic gastrointestinal disease. The same is true of some strains of Escherichia coli that produce toxins. Finally, aromatic amines can come from meat, leading to carcinogenicity in humans.

The focus of chapter nine in the course is alcohol toxicity. While in most cases, this refers to ethanol poisoning and ethanol toxicity, individuals can become toxic and at lower concentrations of alcohol with both methanol poisoning and isopropyl alcohol poisoning. Both of these can be toxic at lower concentrations than is seen with ethanol toxicity. Ethylene glycol is another “toxic alcohol” that is seen mostly with accidental ingestion of the substance. The presentation and management of these toxicities are explained in this chapter.

Chapter ten in the course introduces the topic of the toxicity of ionizing radiation in adults and children. Radiation exposure can be acute, as is seen in wartime situations with atomic bomb blasts or when there is a nuclear disaster. Another type of radiation exposure is more chronic and can be seen in situations like radon exposure in certain homes. Radiation can cause a variety of cancerous and non-cancerous changes in the body.

The focus of chapter eleven is the toxicity of certain illicit drugs. The toxicity of cocaine is covered, including what happens when a person takes in too much of the drug for whatever reason. Opiate toxicity is increasingly important as well as there has been a vast increase in the number of deaths due to opiates in recent years. Finally, the toxicity of methamphetamines is covered as this is also a common drug of abuse, carrying the risk of death when taken in high doses either intentionally or accidentally.

The subject of chapter twelve in the course is bioterrorism and the toxicological implications of this global problem. We discuss bioterrorism in general, including how to recognize it, what the emergency response should be, and the management of possible agents of terrorism. Some things used in terrorist attacks include anthrax, which is covered in this chapter, and ricin—a toxin that has terroristic potential. There is a risk also of terrorism that makes use of the different hemorrhagic viral infections, such as Ebola virus, which is also discussed in this chapter.

Chapter thirteen in the course covers the basics of occupational exposures. There are many things a worker can be exposed to as part of their job, most of them related to the inhalational exposure to various things in the work environment. Exposures can lead to occupational asthma, which can happen in individuals who do not normally have asthma. Other major lung exposures include those to asbestos, silica dust, and beryllium. While personal protective equipment can be used, it may not totally prevent exposure. Hypersensitivity pneumonitis is another lung disease also related to exposure to certain things in the workplace.

The focus of chapter fourteen is animal and plant toxins. There is significant toxicity associated with snake bites that depend on the type of snake that bites the affected individual. There is envenomation from jellyfish stings as from other marine animals. Ciguatera fish poisoning is a specific marine poisoning covered in this chapter. Many different plants can be ingested and are causative of toxicity in children who ingest them. People of all ages can consume harmful mushrooms that can lead to toxicity as well.

Chapter fifteen in the course discusses different forms of endocrine disrupters. Endocrine disrupters basically mean estrogen disrupters, which are chemicals that mimic or inhibit estrogen in the body. These can be found in several sources. Plastics are a major source of endocrine disrupters, containing both phthalates and bisphenol A, also referred to as BPA. There are foods that contain phytoestrogens. The chapter talks about both the theoretical pros and possible cons of taking in these types of foods as well as what they do chemically to mimic estrogen.

Chapter sixteen offers a wide range of topics related to water and air pollution. It focuses mainly on the water pollution that faces the earth and on what things can contribute to the pollution of water. When it comes to air pollution, the chapter talks mainly about things that can be toxic about indoor air pollution. Sick building syndrome is a unique situation in which people have toxic effects because of indoor air quality. Cyanide poisoning mainly comes from indoor domestic fires. Carbon monoxide poisoning is also covered, which is also seen indoors and can be lethal when inhaled for a prolonged period of time or in high doses.