Tox 1

BOS 4201, Toxicology 1

Course Learning Outcomes for Unit I Upon completion of this unit, students should be able to:

1. Summarize important foundational aspects of toxicology. 1.1 Define common terms used in toxicology. 1.2 Identify the types of epidemiological studies used in toxicology. 1.3 Describe the advances that were made in toxicology by its early contributors.

Course/Unit Learning Outcomes

Learning Activity

1.1 Unit Lesson, Unit Reading

1.2 Unit Lesson, Unit Reading

1.3 Unit Lesson, Unit Reading

Reading Assignment Chapter 1: Toxicology and Its Roots as a Science

Unit Lesson This unit introduces the basic concepts, the history, and the terminology used in toxicology. Toxicology and Its Roots as a Science This unit introduces the dose-response relationship and a history of toxicology, including early contributors. In addition, it explains the common terms used in toxicology and identifies the types of epidemiological studies used to determine if a given chemical has the potential for changes in human health. Toxicology is considered as a borrowed science and is defined as the study of the adverse effects of chemicals in biological systems. Some common terms used in toxicology include toxic chemical, toxic substance, toxicant, toxin, poison, toxic agent, and xenobiotic. You need to understand these terms to grasp the concepts in this course. A toxin is a chemical produced by a living organism. A toxicant is a chemical that can cause harm. An example of a toxin produced by the puffer fish is tetrodotoxin. A xenobiotic is a substance that is not normally found in or produced by the body. Examples of xenobiotics include n-hexane (a solvent that affects the nervous system) and paraquat (a herbicide that affects the lungs). A poison is a more general term used to describe a substance, and when it is ingested or absorbed in small amounts, it may cause injury or death (Richards & Bourgeois, 2014). The origins of toxicology go back to 1500 BC with the use of heavy metals. One of the first physicians to apply principles of toxicology was Hippocrates. Additionally, Paracelsus is known as the father of toxicology and recognized for the concept that “the dose makes the poison” (Richards & Bourgeois, 2014, p. 10). Dr. Bernardino Ramazzini wrote the first comprehensive work on occupational medicine (Richards & Bourgeois, 2014). He was followed by Dr. Alice Hamilton, the founder of American occupational toxicology, who wrote the book Exploring the Dangerous Trades. Another physician, Dr. Percival Pott, made a link between chimney sweeps and scrotal cancer. Intentional poisonings also played a role in the history of toxicology. In the 17th century, Madame Giulia Toffana developed a poisonous mixture containing arsenic that she sold with instructions for its use (Richards & Bourgeois, 2014).

UNIT I STUDY GUIDE

The History and Basic Concepts of Toxicology

BOS 4201, Toxicology 2

UNIT x STUDY GUIDE

Title

Dose-response relationships have been demonstrated and well-documented throughout history. The study of toxicology involves many types of substances, including drugs, food additives, chemicals, environmental exposures, household substances, and natural toxins. Both dose and routes of exposure are important considerations when studying toxicology. There are many examples of substances that were initially thought to be harmless, but epidemiological studies proved them to be harmful to human health. In the absence of data from epidemiology studies, where the long-term health effects of substances are unknown, practitioners can use the precautionary principle for controlling exposures to workers and the environment. The dose-response concept will be explored in detail in other units. There are several well-known examples

throughout history that demonstrate a dose-response relationship. The Hawks Nest Tunnel tragedy became a classic case of an occupational disease: silicosis from exposure to silica. Inhalation of silica dust caused fibrosis of the lungs, for which there is no cure. The tunnel was built to divert water, and the rock that was blasted was composed of mostly silica, which resulted in the dust exposure. Silica is also known to cause lung cancer and scleroderma. Another example where the toxicity of a substance became apparent occurred in Minamata Bay, Japan. Methylmercury was released into Minamata Bay by a chemical company. The mercury accumulated in the fish there, and the local population relied mostly on fish for their diet. Over 2,000 people suffered from a neurological syndrome as a result of ingesting the contaminated fish. Epidemiology is used to show a relationship between an exposure and an outcome. Richards and Bourgeois (2014) point out that the types of epidemiology studies include a cohort study, prospective cohort study, retrospective cohort study, case control study, cross-sectional study, and an ecology study. The end results of these studies include a statistical test that results in a relative risk or odds ratio. An example of a cohort study that led to a positive association in workers is a group of workers who were manufacturing a clear rubber known as pliofilm and then developed aplastic anemia. Another example of a positive association is smoking and lung cancer; however, initially, there were many epidemiological studies that showed no association with smoking and lung cancer. An example of a prospective cohort study is the Framingham Heart Study. This study involved over 5,000 residents of Framingham, Massachusetts, and the impact of several factors on incidents of cardiovascular health issues. Currently, there are ongoing studies on the health outcomes of cell phone use. In addition, there are epidemiological studies being published on the respiratory health outcomes of the World Trade Center disaster workers and on over 55,000 workers and volunteers involved in the BP Deepwater Horizon oil spill response. Many times, the epidemiological studies show no proof of an association between the exposure and the response. There are criteria that are used to describe the proof of causation. The descriptors include the strength of association, temporality, consistency, biological plausibility, coherence, specificity, dose-response relationship, experimental evidence, and analogy (Richards & Bourgeois, 2014). Epidemiological studies are not without their faults. The dose-response relationship should show a positive linear relationship between the exposure and outcome. A statistical analysis of the data can give false results, which can lead to a positive association when one does not exist or can lead to a negative association when one does exist. One must also locate a large enough cohort or choose an unexposed group for comparison to get accurate results.

The National Center for Toxicological Research (NCTR) is the U.S. Food & Drug Administration’s (FDA) internationally recognized research center. The unique scientific research expertise of NCTR is critical in supporting FDA product centers and their regulatory science roles. (FDA, 2008)

BOS 4201, Toxicology 3

UNIT x STUDY GUIDE

Title

Modern toxicology is multidisciplinary. There is still research being performed in the area of environmental and occupational diseases. One of the newer topics in toxicology is nanotechnology, which is the study and use of particles in the nanoscopic scale. The small-sized nanoparticles and nanomaterials have different properties, thus different health effects than the same material on a larger scale (e.g., silver nanoparticles react differently than larger silver particles). The long- term health effects of nanoparticles are unknown. An example of how nanoparticles are being used is clothing coated with silver nanoparticles, giving the material antibacterial properties. It does seem apparent that those working with and researching nanomaterials are working under controlled environments, and the risk of exposure is being managed. Similar to other professions, there is an organization for toxicologists. The Society of Toxicology was the first professional organization for toxicologists, and the official journal of the society is titled Toxicology and Applied Pharmacology.

References Richards, I. S., & Bourgeois, M. M. (2014). Principles and practice of toxicology in public health (2nd ed.).

Burlington, MA: Jones & Bartlett. U.S. Food and Drug Administration. (2008). Toxicology research at FDA (NCTR 1231) [Photograph].

Retrieved from https://www.flickr.com/photos/fdaphotos/6008495935/in/photolist-a9X7vv-ciQviW- a9X7Pc-a9X7Fe-a9X7JV-a9X7k4-a9X8jn-a9X7YD-a9ZVME-a9ZUZQ-a9ZW6y-abe4yW-ejCcHn- rcYAth-a9ZVYo-ciPJPh-abe3Vj-a9X7TP-abbcsz-abe45o-abe3Ny-ciRxw5-abbcSt-adg7m5-ciRxCy- addhF6-ciPJLb-ab

Zeiler, E. (2007). 02710007 [Photograph]. Retrieved from

https://www.flickr.com/photos/iaea_imagebank/8388691709/in/photolist-do1pQW-9r6YPw-dMnNE9- dMheMF

Suggested Reading Click here to access the Chapter 1 PowerPoint presentation. Click here to access a PDF version of the presentation.

Learning Activities (Non-Graded) Non-Graded Learning Activities are provided to aid students in their course of study. You do not have to submit them. If you have questions, contact your instructor for further guidance and information.

1. Click here to access the History and Basic Concepts of Toxicology crossword puzzle. Solve the puzzle by filling in the appropriate vertical and horizontal cells with the correct terms from the clues.

2. Once you have completed your puzzle, click here to view the answers to the crossword puzzle. Please try to solve the crossword puzzle without viewing the answers.

Villagers are being interviewed for the International Atomic Energy Agency (IAEA) epidemiological study during the International Chernobyl Assessment Project. (Zeiler, 2007)