chapter 17Review
In this chapter, we learned about human diseases and chemicals that can affect human health and how we analyze the risk of environmental hazards. Human diseases can be categorized as either acute or chronic and can be infectious or not. We reviewed many of the historically important infectious diseases and then discussed the modern problem of emerging infectious diseases. In addition to these biological risks, we also need to consider chemical risks to humans and other species. Chemical risks are assessed by experiments that determine the LD50 or ED50 for various species and by following a large sample of individuals using prospective and retrospective studies. Such risk assessments can be combined with data on risk tolerance to help in risk management, which weighs the assessed risk against social, economic, and political considerations. In conducting risk management, regulators in some regions of the world use the precautionary principle while regulators in other countries, including the United States, use the guilty-
Disease Infectious disease Acute disease Chronic disease Epidemic Pandemic Plague Malaria Tuberculosis Emergent infectious disease Acquired Immune Deficiency Syndrome (AIDS) Human Immunodeficiency Virus (HIV) Ebola hemorrhagic fever Mad cow disease Prion Swine flu Bird flu Severe acute respiratory syndrome (SARS) West Nile virus Neurotoxin Carcinogen Mutagen Teratogen Allergen Endocrine disruptor Dose-response study Acute study Chronic study LD50 Sublethal effect ED50 Retrospective study Prospective study Synergistic interaction Route of exposure Solubility Bioaccumulation Biomagnification Persistence Environmental hazard Innocent-until-proven-guilty principle Precautionary principle Stockholm Convention REACH | The way in which an individual might come into contact with an environmental hazard. An infectious disease with high death rates, caused by the Ebola virus. A disease in which prions mutate into deadly pathogens and slowly damage a cow’s nervous system. A principle based on the belief that a potential hazard should not be considered an actual hazard until the scientific data definitively demonstrate that it actually causes harm. A disease that rapidly impairs the functioning of an organism. How well a chemical dissolves in a liquid. Any impaired function of the body with a characteristic set of symptoms. A chemical that interferes with the normal functioning of hormones in an animal’s body. A 2007 agreement among the nations of the European Union about regulation of chemicals; the acronym stands for registration, evaluation, authorization, and restriction of chemicals. A highly contagious disease caused by the bacterium Mycobacterium tuberculosis that primarily infects the lungs. A 2001 agreement among 127 nations concerning 12 chemicals to be banned, phased out, or reduced. A type of virus that causes Acquired Immune Deficiency Syndrome (AIDS). A chemical that causes allergic reactions. A chemical that interferes with the normal development of embryos or fetuses. A type of flu caused by a coronavirus. A type of flu caused by the H5N1 virus. The length of time a chemical remains in the environment. A situation in which a pathogen causes a rapid increase in disease. A type of carcinogen that causes damage to the genetic material of a cell. The effective dose of a chemical that causes 50 percent of the individuals in a dose-response study to display a harmful, but nonlethal, effect. A situation in which two risks together cause more harm than expected based on the separate effects of each risk alone. An infectious disease caused by one of several species of protists in the genus Plasmodium. A study that monitors people who have been exposed to an environmental hazard at some time in the past. An infectious disease caused by the human immunodeficiency virus (HIV). The increase in chemical concentration in animal tissues as the chemical moves up the food chain. A disease that slowly impairs the functioning of an organism. A principle based on the belief that action should be taken against a plausible environmental hazard. An experiment that exposes organisms to an environmental hazard for a long duration. A virus that lives in hundreds of species of birds and is transmitted among birds by mosquitoes. A chemical that disrupts the nervous systems of animals. Anything in the environment that can potentially cause harm. A study that exposes organisms to different amounts of a chemical and then observes a variety of possible responses, including mortality or changes in behavior or reproduction. An infectious disease that has not been previously described or has not been common for at least 20 years. An epidemic that occurs over a large geographic region. An experiment that exposes organisms to an environmental hazard for a short duration. An infectious disease caused by a bacterium (Yersinia pestis) that is carried by fleas. A type of flu caused by the H1N1 virus. A study that monitors people who might become exposed to harmful chemicals in the future. An increased concentration of a chemical within an organism over time. A disease caused by a pathogen. A chemical that causes cancer. The lethal dose of a chemical that kills 50 percent of the individuals in a dose-response study. A small, beneficial protein that occasionally mutates into a pathogen. The effect of an environmental hazard that is not lethal, but which may impair an organism’s behavior, physiology, or reproduction. |
Module 56 Human Diseases
Identify the different types of human diseases.
Human diseases can be categorized as either infectious or noninfectious. Infectious diseases are caused by pathogens such as viruses, bacteria, fungi, protists, and helminths. Human diseases can also be categorized as either acute, which means they rapidly impair a body’s functions, or chronic, which means they slowly impair a body’s functions.
Understand the risk factors for human chronic diseases.
Risk factors for human health differ between low-
Discuss the historically important human diseases.
Among the historically important infectious diseases, plague is caused by a bacterium that is carried by fleas, malaria is caused by several different species of protists, and tuberculosis is caused by a bacterium that primarily infects the lungs.
Identify the major emergent infectious diseases.
Among the emerging infectious diseases, HIV/AIDS is caused by a virus that weakens the immune system, Ebola hemorrhagic fever is caused by a highly lethal virus, and mad cow disease is caused by a prion that damages the nervous system. In addition, the viruses that cause bird flu and swine flu are easily spread and sometimes lethal, SARS is a type of pneumonia caused by a virus, and West Nile virus normally infects birds but can be transmitted to humans by mosquitoes.
Discuss the future challenges for improving human health
The future challenges for improving human health including the improvement of nutrition and sanitation in low-
Module 57 Toxicology and Chemical Risks
Identify the major types of harmful chemicals.
The major types of harmful chemicals are neurotoxins, carcinogens, teratogens, allergens, and endocrine disruptors. Neurotoxins disrupt the nervous systems of animals and they include insecticides, lead, and mercury. Carcinogens are cancer-
Explain how scientists determine the concentrations of chemicals that harm organisms.
Scientists can conduct LD50 experiments to determine lethal effects of chemicals and ED50 experiments to determine sublethal effects of chemicals. They can also follow large groups of individuals backward in time using retrospective studies or forward in time using prospective studies. Once we know the chemical concentrations that can cause harm, we also need to determine the routes of exposure by which an individual may come in contact with the chemical as well as the chemical’s solubility and its potential to bioaccumulate and biomagnify.
Module 58 Risk Analysis
Explain the processes of qualitative versus quantitative risk assessment.
For a given environmental hazard, we can qualitatively categorize risks as relatively low, medium, or high. However, the actual risk of a given hazard may be quite different from our qualitative assessments. Quantitative assessments use actual data to determine the actual probability of various risks, either based on government death statistics or by calculating the probability of being exposed to a hazard multiplied by the probability of being harmed if exposed.
Understand how to determine the amount of risk that can be tolerated.
Individuals differ in how much risk they are willing to tolerate. For most environmental hazards, we often set risk tolerance at 1 in 1 million.
Discuss how risk management balances potential harm against other factors.
Understanding the level of risk is important, but we must also assess the effects of trying to reduce the risk. Such effects include economic, political, and social considerations that collectively can come to some compromise that balances all of these factors. Whereas risk assessment is conducted by environmental scientists, risk management is typically conducted by local, national, or international government agencies.
Contrast the innocent-
According to the innocent-