Module 10 (Toxicology and Environmental Health Problems) Flashcards
What are Trihalomethanes?
Trihalomethanes (THMs) are the result of a reaction between the chlorine used for disinfecting tap water and natural organic matter in the water. At elevated levels, THMs have been associated with negative health effects such as cancer and adverse reproductive outcomes.
What activities are most likely to increase THM blood levels in humans?
Showering, bathing, and washing dishes
What is a toxic substance?
a substance that can cause adverse health effects
What is a toxin?
A toxic substance that is produced naturally
What is a toxicant?
A chemical that can harm humans, animals, or plants that is produced by (or is a byproduct of) human activities
What is toxicity?
the degree to which a substance is poisonous or can cause injury
What are toxic effects?
health effects that occur due to exposure to a toxic substance
What is potable water?
Drinkable water / water that is safe to drink
What does the adage “the dose makes the poison” mean?
“The dose makes the poison” is an adage intended to indicate a basic principle of toxicology (all substances can be poisonous at the “right” dose). It is credited to Paracelsus who expressed the classic toxicology maxim “All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison.”
What is a threshold dose?
a dose below which the effect does not occur.
In terms of threshold dose, what do NOAEL and LOAEL mean?
NOAEL: no observed adverse affect level (same as the threshold dose)
LOAEL: lowest observed adverse effect level
What are examples of diseases caused by environmental substances?
Coal dust & lung disease
DDT & Reproductive Issues
Ethanol (Alcohol) & Teratogenic Issues
Lead (Neurological Effects)
Beryllium (Hypersensitivity, Immunosuppression)
Formaldehyde (cancer)
What populations are most sensitive to environmental exposures?
low income
minorities
indigenous peoples
children
elderly
disabled
pregnant women
women of childbearing age
What individual factors affect susceptibility to environmental exposures?
nutrition
genetic factors
metabolism
low SES
geography
gender
age
What are endocrine disruptors?
Endocrine disruptors are natural or man-made chemicals that may mimic or interfere with the body’s hormones, known as the endocrine system.
Examples: pharmaceuticals, Dioxin, PCBs, certain pesticides, Bisphenol A (BPA), and PFAS
What is a carcinogen?
A carcinogen is a substance, organism or agent capable of causing cancer
What are some of the best ways to avoid excessive exposure to PFAS?
Avoid nonstick cookware
Eat organic
Avoid frozen produce
Avoid prepackaged foods
What natural study was conducted during the 1996 Olympics in Atlanta?
Reducing traffic and changing commuter behaviors also reduced pollution and asthma
What is selective toxicity?
“Selective toxicity” means that a chemical will produce injury to one kind of living matter without harming another form of life, even though the two may exist close together.
How does toxicity develop?
Before toxicity can develop, a substance must come into contact with a body surface such as skin, eye or mucosa of the digestive or respiratory tract. The dose of the chemical, or the amount one comes into contact with, is important when discussing how “toxic” an substance can be.
What is a dose?
The dose is the actual amount of a chemical that enters the body. The dose received may be due to either acute (short) or chronic (long-term) exposure. An acute exposure occurs over a very short period of time, usually 24 hours. Chronic exposures occur over long periods of time such as weeks, months, or years. The amount of exposure and the type of toxin will determine the toxic effect.
What is dose response?
Dose-response is a relationship between exposure and health effect, that can be established by measuring the response relative to an increasing dose. This relationship is important in determining the toxicity of a particular substance (2). It relies on the concept that a dose, or a time of exposure (to a chemical, drug, or toxic substance), will cause an effect (response) on the exposed organism. Usually, the larger or more intense the dose, the greater the response, or the effect. This is the meaning behind the statement “the dose makes the poison.”
What is a sensitive sub population?
A sensitive sub-population describes those persons who are more at risk from illness due to exposure to hazardous substances than the average, healthy person. These persons usually include the very young, the chronically ill, and the very old. It may also include pregnant women and women of childbearing age. Depending on the type of contaminant, other factors (e.g., age, weight, lifestyle, sex) could be used to describe the population.
What is meant by individual susceptibility?
This term describes the differences in types of responses to hazardous substances, between people. Each person is unique, and because of that, there may be great differences in the response to exposure. Exposure in one person may have no effect, while a second person may become seriously ill, and a third may develop cancer.
What is environmental toxicology?
is concerned with the study of chemicals that contaminate food, water, soil, or the atmosphere. It also deals with toxic substances that enter bodies of waters such as lakes, streams, rivers, and oceans. This sub-discipline addresses the question of how various plants, animals, and humans are affected by exposure to toxic substances.
What is industrial / occupational toxicology?
is concerned with health effects from exposure to chemicals in the workplace. This field grew out of a need to protect workers from toxic substances and to make their work environment safe. Occupational diseases caused by industrial chemicals account for an estimated 50,000 to 70,000 deaths, and 350,000 new cases of illness each year in the United States (1).
What is regulatory toxicology?
gathers and evaluates existing toxicological information to establish concentration-based standards of “safe” exposure. The standard is the level of a chemical that a person can be exposed to without any harmful health effects.
What is food toxicology?
is involved in delivering a safe and edible supply of food to the consumer. During processing, a number of substances may be added to food to make it look, taste, or smell better. Fats, oils, sugars, starches and other substances may be added to change the texture and taste of food. All of these additives are studied to determine if and at what amount, they may produce adverse effects. A second area of interest includes food allergies. Almost 30% of the American people have some food allergy. For example, many people have trouble digesting milk, and are lactose intolerant. In addition, toxic substances such as pesticides may be applied to a food crop in the field, while lead, arsenic, and cadmium are naturally present in soil and water, and may be absorbed by plants. Toxicologists must determine the acceptable daily intake level for those substances.
What is clinical toxicology?
is concerned with diseases and illnesses associated with short term or long term exposure to toxic chemicals. Clinical toxicologists include emergency room physicians who must be familiar with the symptoms associated with exposure to a wide variety of toxic substances in order to administer the appropriate treatment.
What is Descriptive Toxicology?
is concerned with gathering toxicological information from animal experimentation. These types of experiments are used to establish how much of a chemical would cause illness or death. The United States Environmental Protection Agency (EPA), the Occupational Safety and Health Administration (OSHA), and the Food and Drug Administration (FDA), use information from these studies to set regulatory exposure limits.
What is forensic toxicology?
is used to help establish cause and effect relationships between exposure to a drug or chemical and the toxic or lethal effects that result from that exposure.
What is analytical toxicology?
identifies the toxicant through analysis of body fluids, stomach content, excrement, or skin.
What is mechanistic toxicology?
makes observations on how toxic substances cause their effects. The effects of exposure can depend on a number of factors, including the size of the molecule, the specific tissue type or cellular components affected, whether the substance is easily dissolved in water or fatty tissues, all of which are important when trying to determine the way a toxic substance causes harm, and whether effects seen in animals can be expected in humans.
What are the classifications of toxic agents?
Heavy metals
Solvents and vapors
Radiation and Radioactive Materials
Dioxins / Furans
Pesticides
Plant Toxins
Animal Toxins
Sub Categories
General Classifications
What are heavy metals?
Metals differ from other toxic substances in that they are neither created nor destroyed by humans. Their use by humans plays an important role in determining their potential for health effects. Their effect on health could occur through at least two mechanisms: first, by increasing the presence of heavy metals in air, water, soil, and food, and second, by changing the structure of the chemical. For example, chromium III can be converted to or from chromium VI, the more toxic form of the metal.
What are solvents and vapors?
Nearly everyone is exposed to solvents. Occupational exposures can range from the use of “white-out” by administrative personnel, to the use of chemicals by technicians in a nail salon. When a solvent evaporates, the vapors may also pose a threat to the exposed population.
What is radiation / radioactive material?
Radiation is the release and propagation of energy in space or through a material medium in the form of waves, the transfer of heat or light by waves of energy, or the stream of particles from a nuclear reactor (3).
WHat are Dioxins / Furans?
Dioxin, (or TCDD) was originally discovered as a contaminant in the herbicide Agent Orange. Dioxin is also a by-product of chlorine processing in paper producing industries.
What are pesticides?
The EPA defines pesticide as any substance or mixture of substances intended to prevent, destroy, repel, or mitigate any pest. Pesticides may also be described as any physical, chemical, or biological agent that will kill an undesirable plant or animal pest (2).
Describe the Air Quality Index
Describe Atlanta Air Quality
Describe the system of environmental toxins and exposure routes
Describe environmental air exposures
Describe the structure of groundwater versus surface
Describe the general hazardous waste system / continuum
Describe the toxicological paradigm
Describe the toxicology triad
Describe common issues with wastewater (worldwide)
Describe common uses of water in the US
Describe US water use versus population size
Describe the topics covered by the Model Aquatic Health Code
What are Nitrogen Oxides?
Nitrogen Oxides are a family of poisonous, highly reactive gases. These gases form when fuel is burned at high temperatures. NOx pollution is emitted by automobiles, trucks and various non-road vehicles (e.g., construction equipment, boats, etc.)
Describe the EPA’s path to cleaner cars
Is water a limited resource?
However, it is a limited resource; fresh water makes up only about three percent of all water on Earth. Although fresh water is considered a renewable resource, the use of fresh water in some regions exceeds the ability of natural processes to replenish supplies.
