Introduction to Environmental and Occupational Health

Describe environmental policies designed to protect vulnerable groups:

One method for controlling and intervening in children's exposures to environmental hazards is known as the lifecycle approach to identifying exposure pathways. (See Figure 4-6.) Environmental policies can be directed toward the various lifestyle exposure pathways shown in the figure (e.g., prevention of children's oral, dermal, and inhalations exposures to toxicants in the home and outdoor environments). (pg 77)

Discuss the steps involved in risk assessment:

Risk assessment generally takes place in four steps: (1) hazard identification (2) dose-response assessment (3) exposure assessment, and (4) risk characterization. (pg 59) Refer to Figure 3-6 for an illustration. The term risk management shown in the figure is discussed in Chapter 4.

Identify types of associations found between environmental hazards and health outcomes:

The measure of association between exposure and out-come used in case-control studies is known as the odds ratio (OR). (pg 38) The measure of association used in cohort studies is called relative risk (RR) , the ratio of the incidence rate of a disease or health outcome in an exposed group to the incidence rate of the disease or condition in a non-exposed group. (pg 39) Ecologic studies have examined the association between water quality and both stroke and coronary diseases. A group of studies has demonstrated that hardness of the domestic water supply is associated inversely with risk of cerebrovascular mortality and cardiovascular diseases. However, a Japanese investigation did not support a relationship between water hardness and cerebrovascular diseases. In the latter ecologic study, the unit of analysis was municipalities (population sub-divisions in Japan that consisted of from 6,000 to 3 million inhabitants). In analyzing the 1995 death rates from strokes in relationship to the values of water hardness, the researchers did not find statistically significant associations across municipalities. (pg 39) Other ecologic studies have examined the possible as-sociation between use of agricultural pesticides and child-hood cancer incidence. For example, a total of 7,143 incident cases of invasive cancer diagnosed among children younger than age 15 were reported to the California Cancer Registry during the years 1988-1994. In this ecologic study, the unit of analysis was census blocks, with average annual pesticide exposure estimated per square mile. The study showed no overall association between pesticide exposure determined by this method and childhood cancer incidence rates. However, a significant increase of childhood leukemia rates was linked to census block groups that had the highest use of one form of pesticide, called propagate. (pg 37) A case-control study among female residents of Long Island, New York, examined the possible association between exposure to EMFs and breast cancer. 24 Eligible subjects were those who were younger than 75 years of age and who had lived in the study area for 15 years or longer. Cases (n = 576) consisted of women diagnosed with in situ or invasive breast cancer. Controls (n = 585) were selected from the same community by random digit dialing procedures. Several types of measurement of EMFs were taken in the subjects' homes and by mapping overhead power lines. The investigators reported that the odds ratio between EMF exposure and breast cancer was not statistically significantly different from 1; thus, the results suggested that there was no association between breast cancer and residential EMF exposure. (pg 38) In environmental health, agent factors can include (but are not limited to) particulate matter from pollution, toxic chemicals and pesticides, and microbes. Examples of agent factors covered in this text are:Microbial agents responsible for zoonotic diseases • Microbial agents linked to food-borne illness • Toxic chemicals including pesticides • Toxic metals • Airborne particulates and gases • Radiation: ionizing and non-ionizing • These agents are relevant to many of the environmental problems discussed in this text, including hazardous waste disposal, zoonotic illnesses, food-borne illnesses, accidents, occupational illnesses, and adverse health outcomes associated with water and air pollution. (pg 41) Hill's Criteria of Causality Strength Consistency Specificity Temporality Biological gradient Plausibility Coherence (41)

List three human diseases transmitted by arthropod vectors and three caused by zoonoses:

Vector-borne diseases Names of diseases in this group are malaria, leishmaniasis, plague, Lyme disease, and Rocky Mountain spotted fever. Malaria is a disease of great significance for environmental health, even though it does not usually occur in developed regions such as North America, Europe, and Australia. Leish-maniasis affects residents of Middle Eastern countries, where it is endemic, and has been a particular concern of US military personnel stationed in endemic areas. The plague remains a serious threat to the world's population; during the Middle Ages, the "black death" (caused by plague) wiped out millions of people in Europe. Lyme disease, with an epidemic focus in the eastern and upper Midwest United States and an expanding focus in the western United States, also occurs in other parts of the world. (pg 96) See Table 5-2 (pg 97) Zoonoses The hantavirus pulmonary syndrome (HPS) represents a highly fatal condition that is transmitted by rodent vectors. 24 The causative agent is the hantavirus, part of the viral family known as Bunyaviridae. (pg 110) As shown in Figure 5-25, the primary locations for dengue fever are the tropical and subtropical areas of the world, for example, Southeast Asia, tropical Africa, and South America. The virus is thought to have existed among monkeys, and several centuries ago moved to humans in Africa and Asia. Dengue was uncommon until after the mid-20th century, with outbreaks occurring in the Philippines and Thailand in the 1950s and later in the Caribbean and Latin America. (pg 116) According to the CDC, "Monkeypox is a rare viral disease that occurs mostly in central and western Africa. It is called 'monkeypox' because it was first found in 1958 in laboratory monkeys. The disease is caused by Monkeypox virus. It belongs to a group of viruses that includes the smallpox virus (variola), the virus used in the smallpox vaccine (vaccinia), and the cowpox virus. (119) Also known as rabbit fever, tularemia is a bacterial disease associated with Francisella tularensis. The disease is broadly distributed in the United States, and occurs in all states except Hawaii. It is a disease found in rural areas and is linked with wild animals such as rodents, rabbits, and hares. The bacterium may be transmitted in several ways, including the bite of an arthropod (e.g., tick or deer fly), coming into contact with infected animal carcasses, consuming food or water that has been contaminated with the bacterium, or even breathing in the bacterium. (pg 119) Rabies is an acute and highly fatal disease of the central nervous system caused by a virus transmitted most often through saliva from the bites of infected animals; globally, dog bites are the principal source of transmission of rabies to humans. (pg 120)

Name three commonly used insecticides and one commonly used herbicide:

A pyrethrin is an insecticide derived from natural sources, namely certain varieties of chrysanthemum flowers. Pesticides from this group have great ability to paralyze and kill flying insects, although some insects may recover because of their own defensive detoxifying enzymes. (pg 162) Farmers use carbamate-based pesticides as insecticides, fungicides, and herbicides. Some varieties are also in use around the home, an example being the carbamate insecticide carbyl (trade name Sevin), which is used to control garden pests (e.g., wasps, hornets, and snails) and is an ingredient in some products applied to furry pets to control ticks and fleas. (pg 159) DDT; DDT, p, p' (DDT, p, p' is one of the synonyms for • DDT)—Used as an insecticide. (DDT no longer is used as an insecticide in the United States.) (pg 153) Consider the first herbicide in the foregoing list, atrazine, which is one of the most widely used weed killers in the United States. When atrazine is applied as a weed killer on field crops such as corn, runoff from irrigation and rainfall may carry this herbicide into waterways.

Define the term toxicology:

According to its traditional definition, toxicology is the science of poisons. A more complete definition is "the study of the adverse effects of chemicals on living organisms." 6 The science of toxicology is not confined to the study of humans, but can be applied to other species and organisms as well. Through in vivo (in living organisms) and in vitro (in "glass," e.g., cell culture) studies, toxicologists examine such health effects of chemical exposures as carcinogenesis (production of cancer), and damage to internal organs, to the developing fetus, and to the reproductive system. Several types of cancer have been tied to chemical exposure, including carcinoma of the lung, breast, and prostate gland, and some forms of skin cancer and leukemia. (pg 50)

List hazardous substances that may be found in drinking water:

Aluminum, arsenic, disinfection by-products, fluoride, lead, pesticides and radon. (pg 228) Some dramatic instances of waterborne diseases and the presence of lead and other heavy metals in water from the public water supply have been reported by the media. (pg 220)

Discuss the concept of global warming:

An increase in the near surface temperature of the Earth. Global warming has occurred in the distant past as the result of natural influ-ences, but the term is most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases. Sci-entists generally agree that the Earth's surface has warmed by about 1 degree Fahrenheit in the past 140 years. pg 267

Discuss methods used to control vector-borne and zoonotic disease:

Another means to control malaria is the use of bed nets that are impregnated with insecticides.In addition to the use of insecticides, other methods of malaria control include the regular use of suppressive drugs in endemic areas and the avoidance of blood from donors who reside in endemic areas. Sanitary improvements such as the filling and draining of swamps and removal of standing water help to reduce the breeding areas for malaria-carrying mosquitoes. More information on the topic of mosquito control is provided later in the chapter. (pg 101) One method to control mosquito-borne diseases is to monitor for the presence of viruses in sentinel chickens and birds. Some health departments position small flocks of chickens and other birds in strategic locations where mosquitoes may be active. These birds are tested periodically for the presence of viral antibodies. Examples of sentinel birds are shown in Figure 5-34. Mosquitoes are dependent upon water to lead and complete their life cycle. Accordingly, one method for mosquito control consists of removing standing sources of water in which mosquitoes can multiply. (pg 125) See Figure 5-35 for preventative methods.

Describe sources of potable water:

Aquifers are a common source of potable water in many communities. (pg 219) Potable water (drinking water) includes water from wells and runoff from the land's surface. (pg 220) Surface water and groundwater are used as the sources of potable water in the majority of the countries of the world. (pg 238)

Name one chemical used in the manufacture of plastics:

Benzene is a sweet-smelling, flammable, colorless liquid that evaporates rapidly. 66 Benzene is used as an intermediary chemical for the manufacture of plastics, resins, and synthetic fibers. It also is used as a solvent for waxes, paints, resins, oils, plastics, and rubber; it has been added as a component of fuels for motor vehicles. 67 Benzene occurs naturally in gasoline and crude oil, and as a component of cigarette smoke. (pg 169)

Discuss methods for prevention of exposure to toxic metals:

Careful hand washing, personal hygiene, and laundering of clothing will prevent heavy metal-bearing dusts from leaving the workplace and endangering the health of family members. (pg 141) Refer to "How might I be exposed to.." boxes to come up with prevention methods.

Discuss five major environmental laws that have been introduced within the past 10 years:

Clean Air Act (pg 84) Clean Water Act (pg 84) Safe Drinking Water Act (pg 85) National Environmental Policy Act (NEPA) (pg 86) Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) (pg 86) Toxic Substances Control Act (TSCA) (pg 87) Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA-Superfund) (pg 87) Resource Conservation and Recovery Act (RCRA) (pg 87) Occupational Safety and Health Act (pg 87) Endangered Species Act (pg 87)

State a definition of the term environmental health List at least five major events in the history of environmental health: (pg 16)

Comprises those aspects of human health, including quality of life, that are determined by physical, chemical, biological, social, and psychosocial factors in the environment. It also refers to the theory and practice of assessing, correcting, controlling, and preventing those factors in the environment that potentially can affect adversely the health of present and future generations. This section presents a brief review of environmental health history, categorized as follows: ancient history, occupational health (contributions from about 1500 to the mid-1800s), and environmental history post-1800.(pg 16) 1) Hippocrates, who lived between 460 and 370 BC, often is referred to as "the father of medicine." (See Figure 1-11.) Hippocrates emphasized the role of the environment as an influence on people's health and health status in his work titled On Airs, Waters, and Places (ca. 400 BC). The Greek philosopher proposed that environmental and climatic factors such as the weather, seasons, and prevailing winds; the quality of air, water, and food; and one's geographic location were influential in causing changes in human health. He espoused the doctrine of maintaining equilibrium among the body's four humors, known as yellow bile, black bile, phlegm, and blood; imbalance among the four humors caused by environmental influences led to the onset of infectious diseases. (pg 18) 2) The toxic properties of sulfur and zinc were pointed out by the Roman scholar Pliny the Elder (AD 29-79) during the first century AD; Pliny invented a mask constructed from the bladder of an animal for protection against dusts and metal fumes. (pg 18) 3) During the second century AD, the renowned Greek physician Galen (AD 129-200) outlined the pathological aspects of lead toxicity and suggested that mists from acids could endanger the health of copper miners.(pg18) 4) John Snow hypothesized that sew-age-contaminated water was associated with cholera and conducted a "natural experiment" to demonstrate the cause of an outbreak in the present Soho district of London. During Snow's time, one of the explanations for infectious diseases such as cholera was the miasmic theory of disease, which alleged that illnesses were caused by clouds of noxious matter. Snow rejected the miasmatic theory and showed the connection between polluted water and cholera.(pg 19) 5) Beginning in 1900, Walter Reed, who was a US Army medical officer, investigated the causes of yellow fever, which was a scourge of US troops in the Caribbean. He showed that yellow fever was a mosquito-borne affliction. Following this discovery, Major William Gorgas was dispatched to Havana, Cuba, where he implemented a highly successful mosquito eradication program. This action led to a drastic reduction in yellow fever cases in Havana; later Gorgas conducted a mosquito control program in the Panama Canal Zone, making possible the construction of the canal. (pg 20)

Describe three major historical events in environmental epidemiology:

Environmental epidemiology is one of the fields that research fundamental questions regarding the role of environmental exposures in human health. The discipline traces its history from the time of Hippocrates and from early studies of occupational cancer during the late 18th century. Also historically significant were Snow's investigations of cholera during the mid-19th century. (pg 44) Hippocrates In about 400 BC the ancient Greek authority Hippocrates expounded on the role of environmental factors such as water quality and the air in causing diseases. (pg 32) Sir Percival Pott Sir Percival Pott, a London surgeon, was significant to the history of environmental epidemiology because he is thought to be the first individual to describe an environmental cause of cancer. (pg 32) John Snow During the mid-1800s, English anesthesiologist John Snow (see Figure 2-3) linked a cholera outbreak in London to con-taminated water from the Thames River. His methodology for investigating the cholera outbreak of 1849 was known as a "natural experiment," a methodology used currently in the study of environmental health problems. Refer to the text box for more information. (pg 33)

Describe the potential impacts of population growth upon the environment:

Environmental factors that are likely to advance the spread of influenza viruses include intensive animal husbandry practices needed to sup-ply food to the world's growing population. (pg 5) Currently increasing at a geometric rate, the human population threatens to overwhelm available resources; some areas of the world face periodic food scarcity and famine. A number of factors have contributed to population growth, including increases in fertility and reductions in mortality. One of the consequences of population growth has been to encourage the conversion of large rural and forested areas of the earth into cities. Urbanization is linked to numerous adverse implications for the health of populations, including increasing rates of morbidity and mortality. (pg 7) Rapid growth of the world's population contributes to the deterioration of the environment through widespread depletion of natural resources and by causing the levels of air, water, and other forms of pollution to increase. Also, the resources avail-able per person decrease as the total number of individuals on the planet continues to increase geometrically. Consequently, population growth is a determinant of the number of persons who live in poverty. In already-crowded regions, an even larger population means that the size of most people's living spaces must decline and population density must increase. Population density and associated urban crowding are dimensions of environmental degradation associated with increases in the spread of infectious and communicable diseases. (pg 11) The effects of rapid growth of the world's population include: Urbanization Overtaxing carrying capacity (defined later in this chapter) Food insecurity Loss of biodiversity (pg 11)

Provide examples of epidemiologic tools used in environmental health:

Epidemiology aids the environmental health field through: Concern with populations For example, epidemiologic studies of lung disease may examine the occurrence of lung cancer mortality across counties or among regional geographic sub-divisions known as census tracts. Investigators may want to determine whether lung cancer mortality is higher in areas with higher concentrations of "smokestack" industries in comparison with areas that have lower levels of air pollution or are relatively free from air pollution. Use of observational data Studies of the population's health pres-ent a challenge that is partially met by epidemiology because epidemiology is primarily an observational science that takes advantage of naturally occurring situations in order to study the occurrence of disease. Methodology for study designs In the realm of environmental health, epidemiologic research generally aims to portray the frequency of disease occurrence in the population or to link disease outcomes to specific exposures. In order to research environmentally caused disease in the population, the field of environmental epidemiology uses characteristic study designs: cross-sectional, ecologic, case-control, and cohort. For example, these methods are useful in Descriptive and analytic studies In the field of occupational health—which in many respects is emblematic of the general field of environmental health—" Descriptive studies provide information for setting priorities, identifying hazards, and formulating hypotheses for new occupational risk." A historical example (discussed later in this chapter) is William Farr's work showing that Cornwall metal miners had higher mortality from all causes than the general population. One approach of analytic epidemiology is to take advantage of naturally occurring situations or events in order to test causal hypotheses. These naturally occurring events are referred to as natural experiments, defined as "Naturally occurring circumstances in which subsets of the population have different levels of exposure to a supposed causal factor, in a situation resembling an actual experiment where human subjects would be randomly allocated to groups."An example is the work of John Snow, discussed later in this chapter. Many past or ongoing natural experiments are relevant to environmental epidemiology. For example, in some regions of the United States, health legislation prohibits smoking in public areas in order to prevent exposure to secondhand smoke. At the same time, this activity may be considered a natural experiment that impacts human health and that can be studied by environmental epidemiologists. (pg 29 + 30)

List common substances that are included in the organophosphate group:

Examples of OP pesticides are diazinon, malathion, methyl parathion, and parathion. Pesticides from the organophosphate group appear in a wide variety of products: sprays, baits, indoor foggers and bombs, flea collars, pet shampoos, powders, animal dips, and granules. Some OP pesticides (e.g., malathion) are approved for direct application to food crops such as fruits (e.g., apples and grapes), row crops, and vegetables (e.g., tomatoes). A more extensive list of OP pesticides is provided in Table 7-4, with the trade names of some of the pesticides shown in brackets. (pg 157) Styrene (styrene monomer) is a clear, colorless liquid that has an aromatic odor. 71 It is commercially important for the manufacture of polystyrene resins (used for many types of plastics, such as packaging, disposable drinking glasses, and building insulation). Short-term inhalation of styrene can produce central nervous system effects such as muscle weakness, and problems concentrating on tasks; irritation of the respiratory tract also can result. According to the IARC, styrene has been listed as possibly carcinogenic, although the evidence supporting this effect among humans and in animal studies is limited. (pg 170) At room temperature, vinyl chloride (synonyms: chlo-roethene, chloroethylene, ethylene monochloride, monochlo-roethylene) is a colorless, flammable gas that has a distinctive sweet odor and is highly volatile. 72 When kept under pressure or at low temperatures, vinyl chloride becomes liquefied. In the United States, vinyl chloride is used mainly for the manufacture of polyvinyl chloride, which is an ingredient of a multitude of plastic products such as pipes, vinyl siding for houses, plastic coatings, and upholstery. (pg 170)

Describe methods for human exposure assessment:

Exposure assessment is defined as the procedure that "identifies populations exposed to the toxicant, describes their composition and size, and examines the roots, magnitudes, frequencies, and durations of such exposures." (pg 59) Available methods are unable to provide adequate quantitative information regarding how much humans are exposed to toxic substances as well as the specific kinds and patterns of exposure. The quality of exposure assessment data determines the accuracy of risk assessments and therefore is a limiting factor in the risk assessment process. (pg 61) Several methods of exposure assessment (e.g., personal exposure monitoring and use of biological markers) are used in toxicology, environmental epidemiology, and other environmental health disciplines. (pg 61) During a review of records to assess exposure, the investigator may select a study population from personnel records maintained by a company. If the records of former and retired workers are retained by the company, a complete data set spanning long time periods may be available. (pg 61) Some environmental studies use biomarkers that may be correlated with exposures to potential carcinogens and other chemicals. These biomarkers involve changes in genetic structure that are thought to be the consequence of an exposure. (pg 61) One marker is called a sister chromatid exchange (SCE). SCE's refer to reciprocal exchanges of DNA between pairs of DNA molecules. 33 In a study of exposure to styrene gas (involved in boat-building and plastics manufacture), researchers examined the utility of SCE's in comparison with environmental monitoring, and exhaled styrene levels as alternative measures of styrene exposure. The use of biomarkers such as SCE's is growing in the environmental health field. (pg 63)

Describe employment opportunities in the environmental health field:

Hygienist (pg 22) Toxicologist (pg 22) Environmental Health Inspector (pg 22) Food inspector/Safety Specialist (pg 22)

Indicate how a disease may be transmitted from an animal reservoir to humans:

In some cases a zoonosis may be a disease-causing pathogen that maintains an infection cycle in a host that is independent from humans, who can become inadvertent hosts. Other definitions refer to organisms that can infect both humans and animals during their life cycles. Conceptions of zoonotic agents may also include pathogens that cause disease in a nonhuman host or situations in which an infected animal remains free from symptoms of the disease. Contact with the skin, the bite or scratch of an animal, direct inhalation or ingestion (e.g., eating contaminated foods such as infected meat), or the bite of an arthropod vector are some of the methods for transmission of zoonotic pathogens. Note that immunocompromised persons, infants, and children younger than five years old may be at increased risk of morbidity from zoonotic diseases (e.g., toxoplasmosis) transmitted by cats and dogs. Table 5-2 provides examples of zoonotic diseases and animals that are associated with those diseases. (pg 96)

Discuss the impact of human environmental change on emerging infectious diseases in animals and man:

In the late 1980s and early 1990s, Kenya experienced an upward movement of malaria cases, possibly due to small changes in climate that provided suitable conditions for malaria to survive. (pg 101) The environmental factors hypothesized to be responsible for increases in leishmaniasis include movement of the human population into endemic areas, increasing urbanization, extension of agricultural projects into endemic areas, and climate change due to global warming. (103) Among the most commonly identified factors associated with the rise of emerging zoonoses are ecological changes that result from agricultural practices (e.g., deforestation, conversion of grasslands, and irrigation). Other factors include changes in the human population and human behavior (e.g., wars, migration, and urbanization). Table 5-3 presents examples of emerging zoonoses and lists conditions that may be linked to their occurrence. In the following sections, some of these emerging zoonoses will be covered in more detail. (pg 110)

Describe potential hazards linked to indoor air:

Indoor air that is of poor quality can be a significant factor in the etiology of lung disease and exacerbation of existing conditions such as asthma and bronchitis....The indoor environment provides many opportunities for exposure to potentially irritating and harmful substances. Examples are aerosolized chemicals, fumes from gas appliances, components of building materials, and secondhand smoke from tobacco products. Adverse health outcomes that have been linked to indoor pollution include respiratory dis-eases such as asthma, Legionnaires' disease, the sick building syndrome, hypersensitivity pneumonitis, and multiple chemical sensitivity. presence of cockroaches, persistent dampness, wall-to-wall carpeting in children's bedrooms, exposure to environmental tobacco smoke, infestations with rodents, and pets that have fur. 47 Other factors that influence the quality of indoor air are effluents from gas stoves and the use of construction materials that contain formaldehyde. 60 Dust mites, molds, and bacteria, all of which are linked with asthma, also may be identified in indoor air. 61 Evidence suggests that children who become sensitized to allergenic indoor air pollutants such as molds and animal fur may incur an increased risk for the development of asthma. 61 Dwellings that have damp, odiferous interiors may be conducive to the growth of fungi, dust mites, and bacterial pathogens, all of which, in turn, tend to be related to respiratory symptoms.A frequent cause of indoor air pollution in developing coun-tries is the use of unventilated indoor cooking stoves that burn biomass fuels (wood, animal dung, or cuttings from crops).Often biomass fuels are combusted in crude stoves or pits that have been dug into the floor. Due to inefficient combustion and the lack of ventilation in household areas used for cook-ing, the house fills up with smoke. As a result, the persons who occupy the dwelling may be exposed to substantial amounts of pollutants: PM 10 , carbon monoxide, nitrous oxides, sulfur compounds, and polycyclic aromatic hydrocarbons pg 264

Describe sources and types of ionizing and non-ionizing radiation:

Ionizing radiation consists of either particulate energy (e.g., highly energetic protons, neutrons, and α and β par-ticles) or electromagnetic energy in the form of photons (e.g., γ rays and X-rays). Ionizing radiation is "radiation capable of producing ions or charged particles." 4 When ionization oc-curs, "[a]n orbital electron is stripped from a neutral atom, producing an ion pair (a negatively charged electron and a positively charged atom)." 4 Ionizing radiation may damage "living tissue in the human body. . . . The body attempts to repair the damage, but sometimes the damage is of a nature that cannot be repaired or it is too severe or widespread to be repaired. Also mistakes made in the natural repair process can lead to cancerous cells." pg 197

Name five heavy metals that pose health hazards to humans:

Major Toxic Metals Arsenic (As) Beryllium (Be) Cadmium (CD) Chromium (Cr) Lead (Pb) Mercury (Hg) Nickel (Ni) Metals with Toxic Potential Cobalt (Co) Trivalent chromium, Cr(III) Copper (Cu) Iron (Fe) Magnesium (Mg) Manganese (Mn) Molybdenum (Mo) Selenium (Se) Zinc (Zn) Minor Toxic metals Antimony (Sb) Barium (Ba) Germanium (Ge) Indium (In) Silver (Ag) Tellurium (Te) Thallium (Tl) Tin (Sn) Titanium (Ti) Uranium (U) Vanadium (V) (pg 131)

Describe historically important air pollution episodes:

Meuse Valley in Belgium One of the earliest modern episodes of hazardous air pollution occurred during the first week of December 1930, had a high concentration of steel industry operations (e.g., foundries, mills, coke ovens, and smelters). During an infamous episode of severe air pollution, sulfur dioxide, sulfuric acid mists, and fluoride gases rose to extremely high levels. This noxious mixture was thought to be associated with the deaths of more than 60 persons during the last two days of the incident. The resulting mortality was more than 10 times the normal mortality rate. Most of the fatalities occurred among the elderly who had preexisting heart and lung diseases. Donora, Pennsylvania October 27 to October 30, 1948,fog combined with particulate matter and industrial and other contaminants. The sources of the contaminants were iron and steel mills, coal-fired home stoves, factories that burned coal, coke ovens, and metal works. This episode caused some form of illness among approximately half of the town's 14,000 residents; about 400 of them were hospitalized, and 20 died before the smog finally lifted at the end of October. 7,8 Figures 10-3 and 10-4, respectively, show how the town was obscured by air pollution on various days around the time of the smog episode and the locations of people who died.Although the episode of late October affected a wide cross-section of age groups, those who were aged 55 years and older tended to be the most severely affected. During the incident, persons who were stricken reported respiratory symptoms (cough, sore throat, difficulty breathing) and gastrointestinal symptoms (nausea and vomiting). Previous histories of heart disease and lung disease were contributing factors to the adverse outcomes of smog exposure. The Lethal London Fog of 1952 Traditionally, London had been known for its foggy climate coupled with smoke caused by the use of coal and other fossil fuels to heat homes, run power plants, and operate factories. At least 1 million coal stoves spewed forth choking sulfurous smoke. As a result, so-called "pea-souper" fogs were well-known to the residents of the English metropolis. The consequence of the particularly lethal fog that occurred in December 1952 was a reported excess of 3,000 deaths above normal. Many environmental health experts consider the London fog of 1952 to be a landmark for the study of the health effects of air pollution and a catalyst that has led to research in this field. All on page pg 247

Describe occupational settings in which workers are exposed to toxic metals:

Occupational exposure to cadmium comes from the production of nickel cadmium batteries, zinc smelting, manufacture of paint pigments, soldering, and employment in metal factories. In occupational settings, the modes for entry of cadmium into the body are primarily through inhalation and, secondarily, through the gastrointestinal tract. (pg 137) Early in the 20th century, occupational health specialists observed that employees in the chromium ore industry in Germany had higher rates of lung cancer than the general population. (pg 138) A Spanish epidemiologic study investigated whether job-related exposure to lead or cadmium was associated with elevated blood pressure levels among two groups of workers in Barcelona. 39 One group was employees who were exposed to lead (e.g., welders); the second group consisted of workers who were exposed to cadmium in pigment and resin factories. Researchers found that workers exposed to lead showed a significant increase in blood pressure, whereas those exposed to high levels of cadmium did not show such an increase. Apparently, in this research, high levels of exposure to these two heavy metals had differential effects upon blood pressure. (pg 144) The occupational environment is a source for significant exposure to nickel. For example, some metal workers risk exposure to nickel and nickel compounds through inhalation or skin contact. One of the common reactions to skin contact with nickel is nickel allergy, manifested as contact dermatitis. Other effects of nickel exposure include cardiovascular related and renal diseases as well as fibrosis of the lungs. One of the concerns about nickel is its potential carcinogenic action. For example, epidemiologic studies have suggested that nickel miners have a higher incidence of nasal cancer as well as lung cancer than the non-exposed population. Other occupational exposures to nickel occur in the production of nickel through refining, as well as processing the metal via electroplating and welding. (pg 145) Workplace exposures to copper arise from breathing dust stirred up by mining and processing copper-rich ore. Other exposures result from inhalation of fumes and dust generated during the welding and grinding of copper metal. (pg 145)

Discuss the health effects of exposure to pesticides:

Organophosphate poisoning can produce both acute and long-term effects. In the former case, the anticholinesterase activity happens soon after exposure and causes impairment of the neural impulse transfer mechanism. A group of im-mediate symptoms may occur: Nerves and muscles may be-come uncoordinated, producing respiratory paralysis and weakness; neurological symptoms may include seizures and loss of consciousness; cramping of the abdominal area may occur; and in extreme cases, death may ensue. The effects of long-term exposure may include a condition known as organophosphate-induced delayed polyneuropathy, which is manifested by numbness, loss of sensory abilities, and weak-ness. Clinicians believe that in most cases this delayed form of polyneuropathy is irreversible. (pg 157) Methyl isocyanate (MIC) is an intermediate chemical used for the manufacture of carbamate pesticides. Also, MIC is created as metam sodium breaks down. When acute expo-sure occurs, MIC is extremely toxic to life-forms (e.g., human beings, aquatic organisms, and plants). A notorious incident that involved the pesticide was the accidental release of MIC during a 1984 industrial accident in Bhopal, India, that killed more than 3,800 people. (pg 160) Organochlorines pose a range of adverse human health risks and some are carcinogens.The various human health effects that have been linked to DDT include cancer, reproductive effects, impaired lactation, falling sperm counts, and impaired neurologic function. Among the forms of cancer associated with DDT in some studies are pancreatic cancer, non-Hodgkin's lymphoma, and breast cancer. DDT also causes nervous system abnormalities among pesticide workers; these symptoms include irritability, dizziness, and numbness. "Other than the long-recognized neurologic toxicity associated with DDT poisoning, and laboratory ab-normalities [e.g., abnormal results from blood tests] in DDT-exposed workers, human health effects of DDT exposure are not established." (pg 161) High levels of exposure to pyrethrin-based insecticides produce characteristic acute effects such as nausea, headache, dizziness, and neurologic symptoms. The following text box documents episodes of human illness due to exposure to pyrethrins and pyrethroids. (pg 162)

State five factors that affect responses to a toxic chemical:

Several factors determine whether an individual will respond to exposure to a toxic chemical and the type of response that occurs. (pg 55) The concentration and toxicity of the chemical are affected by the following: Route of entry into the body (pg 55) The most frequent sites of exposure to environmental (i.e., xenobiotic) chemicals include the gastrointestinal tract, the respiratory system, and the skin. (Refer to Table 3-2.) With respect to route of exposure, chemicals may enter the body intentionally (as in the example of medical interventions) or unintentionally (through accidents or environmental exposures). (pg 55) Received dose of the chemical (See dose-response on page 54) Duration of exposure Acute exposures may produce acute effects that disappear rapidly, although this outcome is not invariable. In comparison with short-term exposures, chronic exposures may allow for the buildup of effects over time with the resulting accumulation of biological damage. However, such accumulation may not occur if the chemical is excreted before the next exposure happens. (pg 56) Interactions that transpire among multiple chemicals When an organism is exposed to two or more chemicals, their combined effects may be additive, synergistic, antagonistic, or coalitive; some chemicals may cause potentiation. (pg 57) Individual sensitivity The responses of individuals to toxic substances can vary greatly, ranging from no apparent response to severe re-sponses. Responses may vary according to age, sex, race, and health status. Other influences include the person's genetic background, use of medications, consumption of alcohol, and pregnancy status. Some chemicals (e.g., bee venom) produce severe or life-threatening reactions in persons afflicted with allergies. (pg 57)

List study designs used in environmental epidemiology:

Study designs used in environmental epidemiology are similar to those developed for general epidemiologic research. Study designs can be arranged on a continuum ranging from hypothesis-generating designs that provide limited information to complex hypothesis-testing designs. Purely observational study designs include case series, cross-sectional, ecologic, case-control, and cohort studies. Non-observational and partly observational designs that are used include experimental and quasi-experimental designs. (pg 34)

State four principles that guide environmental policy development:

The Precautionary Principle States that "preventive, anticipatory measures should be taken when an activity raises threats of harm to the environment, wildlife, or human health, even if some cause-and-effect relationships are not fully established." The practice of risk assessment is a science of uncertainty, so environmental toxins often present risks that have not been ascertained completely. The precautionary principle suggests that policy makers should err on the side of "an ounce of prevention" and take protective measures even when full scientific certainty is lacking. (pg 69) Environmental Justice Denotes the equal treatment of all people in society irrespective of their racial background, country of origin, and socioeconomic status. The presence of an environmental hazard may be the end product of disparities of power and privilege within a community. Consequently, unequal toxic exposures of adults and children from different racial, ethnic, or socioeconomic groups may occur. Children of color may receive especially high exposures to environmental toxins. (pg 69) Environmental Sustainability As a goal of environmental policy, environmental sustainability adheres to the philosophical viewpoint "that a strong, just, and wealthy society can be consistent with a clean environment, healthy ecosystems, and a beautiful planet." The three components of sustainable development are materials and energy use, land use, and human development. Environmental sustainability means that resources should not be depleted faster than they can be regenerated; the concept also specifies that there should be no permanent change to the natural environment. Critics of sustainable development argue that the definition of the term is not entirely clear and is open to interpretation. (pg 69) The Polluter-Pays Principle "Means that the polluter should bear the expenses of carrying out the pollution prevention and control measures introduced by public authorities in Member countries, to ensure that the environment is in an acceptable state." 14 The principle, implemented by the OECD in November 1974, applies to pollution that originates from a variety of sources including accidental releases during manufacturing processes and from installations that handle hazardous materials. The costs of controlling pollution generated during manufacturing and consumption are to be incorporated into the prices of associated goods and services. (pg 70)

Describe key environmental health regulatory agencies at the international, national, state/provincial, and local levels:

The World Health Organization (WHO) A major international agency that is responsible for environmental health at the global level. WHO provides leadership in minimizing adverse environmental health outcomes associated with pollution, industrial development, and related issues. Although WHO's primary mission is to control and prevent disease, its reach extends to environmental health, which is closely related to disease prevention. More information about WHO is presented later in this chapter. (pg 79) (pg 83) Environmental Protection Agency EPA leads the nation's environmental science, research, education and assessment efforts. The mission of the Environmental Protection Agency is to protect human health and the environment. Since 1970, EPA has been working for a cleaner, healthier environment for the American people. In July of 1970, the White House and Congress worked together to establish the EPA in response to the growing public demand for cleaner water, air and land. Prior to the establishment of the EPA, the federal government was not structured to make a coordinated attack on the pollutants that harm human health and degrade the environment. (pg 80) The National Institute for Occupational Safety and Health (NIOSH) The federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. The mission of the NIOSH is to generate new knowledge in the field of occupational safety and health and to transfer that knowledge into practice for the betterment of workers. To accomplish this mission, NIOSH conducts scientific research, develops guidance and authoritative recommendations, disseminates information, and responds to requests for workplace health hazard evaluations. Occupational Safety and Health Administration (OSHA) is in the US Department of Labor and is responsible for developing and enforcing work-place safety and health regulations. NIOSH is part of the Centers for Disease Control and Prevention (CDC) . . . in the Department of Health and Human Services. . . . NIOSH is an agency established to help assure safe and healthful working conditions for working men and women by providing research, information, education, and training in the field of occupational safety and health. (pg 80) The Agency for Toxic Substances and Disease Registry (ATSDR) The nation's public health agency for chemical safety. The agency's mission is to use the best science, take responsive action, and provide trustworthy health information to prevent and mitigate harmful exposures to toxic substances and related disease. (pg 81) The National Institute of Environmental Health Sciences (NIEHS) One of 27 Institutes and Centers of the National Institutes of Health (NIH), which is a component of the US Department of Health and Human Services (HHS). The mission of the NIEHS is to reduce the burden of human illness and disability, by understanding how the environment influences the development and progression of human disease. NIEHS's broad focus on the environmental causes of disease makes the institute a unique part of the NIH. Federal and state regulatory, environmental, and public health agencies use NIEHS research to calculate new standards to protect health of people throughout the world. (pg 82) The European Environment Agency (EEA) Located in Copenhagen, Denmark, is an arm of the European Union. The EEA is tasked with the mission of supplying information to 32 member countries regarding the environment. This information is used for environmental policy development, adoption, implementation, and evaluation. Environmental Advocacy Organizations Although they are not components of government, environmental advocacy organizations constitute an important part of the fabric of environmental policy formulation and are a significant force in influencing public policy. (pg 83) Local government agencies Such as health departments also are closely connected with enforcement of environmental laws. For example, the City of Long Beach Department of Health and Human Services (DHHS), one of the city health departments in California, operates an environmental health division. This division is responsible for water quality, hazardous materials management, community sanitation, vector control, lead poisoning, food inspection, and housing quality (pg 79) See Table 4-5 on page 80

Describe how environmental health problems influence our lives:

The environment is intimately connected with human health, illness, and mortality: Some estimates place the toll of the world's deaths caused by environmental factors at 40%. Exposures to potentially hazardous agents such as microbes, toxic chemicals and metals, pesticides, and ionizing radiation account for many of the forms of environmentally associated morbidity (acute and chronic conditions, allergic responses, and disability) and mortality that occur in today's world. These environmentally related determinants are believed to be important for the development of chronic diseases such as cancer, although most chronic diseases are thought to be the result of complex interactions between environmental and genetic factors. All human beings are affected in some way by exposure to environmental hazards associated with life-style: at work, at home, during recreation, or while traveling on the expressway.(Page 5) Examples of physical environmental factors (as noted previously) that affect human health include toxic chemicals, metallic compounds, ioniz-ing and nonionizing radiation, and physical and mechanical energy. (pg 14)

Describe the potential health effects of exposure to household cleaning products:

The form known as 1,1,1-trichloroethane (synonym: methylchloroform) is a sol- vent found in degreasing compounds and household cleaners that has had many other uses. 60 Depending upon the level of exposure, symptoms range from dizziness to loss of consciousness. Although not presently classified as a carcinogen, its manufacture has been discontinued since January 1, 2002, because of potential to harm the ozone layer. (pg 169) Trichloroethylene (TCE) is a grease-dissolving solvent that evaporates readily. 62 In addition to its use as a solvent, TCE is added to some cleaning agents, paint removers, and adhesives. In the environment, TCE may persist in underground water supplies for long periods. Low exposure levels produce neurologic effects such as dizziness and headaches. Inhalation or ingestion of large amounts of TCE can cause unconsciousness and death. Acetone , a colorless liquid with a distinctive sweet odor, is used as an ingredient in nail polish, cleaners, and paints. 64 This highly volatile solvent is flammable and dissolves in water. Moderate levels of exposure to acetone can cause irritation of the eye (e.g., tearing) and the respiratory tract (e.g., nose, throat, and lungs). High levels are capable of causing headaches, vomiting, and loss of consciousness. (pg 169) See Table 7-6 on page 172

Define what is meant by the hydrological cycle:

The natural cycle by which water evaporates from oceans and other water bodies, accumulates as water vapor in clouds, and returns to oceans and other water bodies as precipitation. (pg 212) The hydrological cycle is akin to a pumping system, driven by the sun, which moves freshwater from the oceans to land-masses and then returns it to the ocean. This cycle describes the process by which the freshwater supply is continuously replenished. Refer to Figure 9-6.The United Nations Environment Program provides the following description of the hydrological cycle: Water is transported in different forms within the hydrological cycle or "water cycle." Each year about 502,800 km 3 of water evaporates over the oceans and seas, 90% of which (458,000 km 3 ) returns directly to the oceans through precipitation, while the remainder (44,800 km 3 ) falls over land. With evapotranspiration totaling about 74,200 km 3 , the total volume in the terrestrial hydrological cycle is about 119,000 km 3 . About 35% of this, or 44,800 km 3 , is returned to the oceans as run-off from rivers, groundwater and glaciers. A considerable portion of river flow and ground-water percolation never reaches the ocean, having evaporated in internal runoff areas or inland basins lacking an outlet to the ocean. However, some groundwater that bypasses the river systems reaches the oceans. Annually the hydrological cycle circulates nearly 577,000 km 3 of water. (pg 214)

List the steps in the policy-making process:

The policy cycle refers to the distinct phases involved in the policy-making process. (Refer to Figure 4-1.) The policy cycle comprises several stages: (1) problem definition, formulation, and reformulation; (2) agenda setting; (3) policy establishment (i.e., adoption and legislation); (4) policy implementation; (5) policy assessment. The terms subsumed under the policy cycle are illustrated in Table 4-1. Problem definition, formulation, and reformulation are terms that denote the processes of defining the problem for which the policy actors believe that policies are necessary. This early stage—problem definition and development of alternative solutions—often is regarded as the most crucial phase of the policy development process. Agenda setting refers to setting priorities, deciding at what time to deal with the environmental problem, and determining who will deal with the problem. Policy establishment involves the formal adoption of policies, programs, and procedures that are designed to protect the public from environmental hazards. (pg 70) Policy implementation is the phase of the policy cycle that "focuses on achieving the objectives set forth in the policy decision." Often this phase of the policy cycle is neglected in favor of the earlier phases of policy development. Assessment/evaluation, the final stage in the policy cycle, refers to assessment of the effectiveness of the policy. In order to facilitate assessment, environmental policies may incorporate environmental objectives , which "are statements of policy. Intended to be assessed using information from a monitoring program. (pg 71)

Enumerate the typical components of urban ambient air pollution:

The problem of urban air pollution is continuing to grow more acute in the developing world, where populations are expanding rapidly and fast-paced industrialization is coupled with increasing use of motor vehicles. In the developing areas, the use of fossil fuels has contributed to worsening air pollu-tion. pg245) Air pollution scientists attribute urban ozone, acid rain, and oxygen depletion of coastal waters to NO (pg 251) Residents (both children and adults) of urban areas may be exposed to diesel exhaust from motor vehicle traffic. exhaust causes cancer... pg 257

Discuss hazards to the aquatic environment (oceans,lakes, rivers) associated with environmental pollution:

The problem of water quality is especially acute for developing nations. In these countries up to 90% of the cities discharge their untreated sewage into rivers and streams. During heavy rains urban runoff into the oceans degrades the quality of ocean water by adding microbial agents, nutrients, and chemical toxins. The problem of urban runoff is compounded by developments that result in the loss of wetlands , which act as natural water-filtering mechanisms. Excessive amounts of nutrients that enter the oceans may cause harmful blooms of algae, resulting in reduced levels of oxygen in the water (anoxic conditions). An anoxic ocean environment can bring about fish kills and damage other forms of ocean life. Urban runoff and sewage contamination of the ocean expose swimmers to waterborne diseases—gastrointestinal, respiratory, skin, and eye infections. Storm water runoff is a leading cause of ocean pollution. Garbage that is discarded carelessly on the street may end up in the ocean or on beaches, as Figure 9-26 demonstrates. Following heavy rains, visitors to the beach are likely to find massive quantities of non-biodegradable plastics (e.g., Styrofoam cups, rings from beverage six-packs, and plastic bags) that are littering the shoreline. In addition to being offensive, these materials endanger birds and fish. Motor vehicle oil and automotive chemicals that are dumped carelessly into storm drains also eventually pollute the ocean. Increase in bacteria leads to shut down of beaches All on page 231

Identify current issues in the environmental health field:

The requirements of a growing world population need to be balanced against the demands for environmental preservation. Although developed countries such as the United States have made substantial progress in clearing the air and reducing air pollution, significant challenges to the environment and human health remain. For example, among the current and continuing threats to the environment in the United States are the following: trash that fouls our beaches, hazardous wastes (including radioactive wastes) leaching from disposal sites, continuing episodes of air pollution in some areas, exposures to toxic chemicals, and destruction of the land through deforestation. (Page 4) For example, one issue that commands our attention (and that has generated extensive coverage in the media) is the prospect of global climate change including global warming (and production of greenhouse gases). Among the outcomes believed to be associated with global warming are changes in the distribution of insect vectors that can carry diseases such as malaria and the West Nile virus. (Page 20) The impact of toxic pesticides and toxic chemicals is a major issue for environmental health. For example, toxic materials have been introduced into the drinking water supplies of some communities. (Page 20) A related issue concerns the runoff of rainwater that overtaxes sewage processing facilities, resulting in pollution of public beaches and groundwater. (pg 21) Still another issue is the impact of air quality on human health, including the role of air pollution in causing cancer and lung diseases as well as aggravating chronic conditions such as heart disease. (pg 21)

Distinguish between essential and toxic levels of trace metals:

The second group consists of metals that are considered to be essential for life when present in trace amounts; examples are iron, copper, manganese, and zinc. However, concentrations greater than trace amounts have the potential for toxicity. (pg 131) Copper, zinc, and iron, examples of metals that are essential for human nutrition, can be toxic if ingested in excessive amounts. An optimal range of these essential metals is necessary to maintain health. When insufficient amounts of these trace metals are consumed, dietary deficiencies can result. (pg 145)

Define the term environmental epidemiology:

The term environmental epidemiology refers to the study of diseases and health conditions (occurring in the population) that are linked to environmental factors. 3,4 The exposures, which most of the time are outside the control of the individual, usually may be considered involuntary and stem from ambient and occupational environments. (pg 28) Exposure of populations to secondhand cigarette smoke would be a concern because nonsmokers and vulnerable groups such as children cannot control whether they are exposed to environmental tobacco smoke. (pg 28)

Define the terms ionizing radiation and non-ionizing radiation:

The term ionizing radiation denotes radiation that "has enough energy to remove tightly bound electrons from atoms, thus creating ions. This is the type of radiation that people usually think of as 'radiation.'.. nonionizing radiation refers to "[r]adiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons. . . pg 177

List health effects associated with air pollution:

The term smog complex refers to "eye irritation, irritation of the respiratory tract, chest pains, cough, shortness of breath, nausea and headache" associated with smog. 3 In our homes, at work, and in other enclosed spaces, we may be exposed to secondhand cigarette smoke, allergens, potentially toxic molds, and hazardous chemicals.High levels of air pollution can endanger our health and can kill people as well, especially when reactive gases are discharged into the atmosphere and when vulnerable persons are exposed. Health effects associated with air pollution include some forms of cancer such as lung cancer and skin cancer (from possible depletion of the ozone layer), damage to vital tissues and organs such as the nervous sys-tem, and impairment of lung and breathing function. There have been numerous occasions of air pollution-caused mortality. (pg 241)

Define what is meant by a vector-borne disease and a zoonotic disease:

The term vector-borne infection refers to "several classes of vector-borne infections each with epidemiological features determined by the interaction between the infectious agent and the human host on the one hand and the vector on the other. Therefore, environmental factors, such as climatic and seasonal variations, influence the epidemiologic pattern by virtue of their effects on the vector and its habits." 2 Vector-borne infections spread by biological transmission, which refers to "transmission of the infectious agent to a susceptible host by bite of blood-feeding (arthropod) vector, as in malaria, or by other inoculation, as in Schistosoma infection." (pg 96) The term zoonosis refers to "An infection or infectious disease transmissible under natural conditions from vertebrate animals to humans." The definition of zoonosis varies to include several different situations. (pg 95) Vector-borne = Generally, insect to human Zoonotic = animal to animal OR animal to insect to human (vector-borne).

State mechanisms for exposure of humans to toxic metals:

There are several possible modes of exposure to metals, cor-responding to the human portals and sites of entry that come into contact with the metals. These portals and sites include the lungs (through inhalation of dusts, metal fumes, and vapors), skin (through contact with dusts), and the mouth (by ingestion). Contact with high concentrations of toxic metals is most likely to occur in an occupational setting (e.g., among persons who work with metals). Lower-level exposures may result from contact with the ambient environment. For example, children may ingest toxic metals that are present in paints in homes and playgrounds. Also, people may be exposed to levels of toxic metals in the foods that they eat. (pg 131) Four major types of media have potential for exposure of the population to heavy metals. As shown in Table 6-2, these media are air, soil/dust, water, and biota (animal and plant life)/food. Some media are more relevant to the transport of a given type of heavy metal than are other media. For example, water is a medium for exposure of the population to arsenic and lead. Food is a medium for exposure of the population to mercury. (pg 132)

Define three important terms used in the field of toxicology:

Toxicology contributes to the armamentarium of tools that are crucial to the description and characterization of environmental chemicals and the responses of living organisms to these chemicals. Related to the functions of toxicology are assessment of exposure, risk, and hazards. (pg 49) Exposure Exposure is defined as "proximity and/or contact with a source of a disease agent in such a manner that effective transmission of the agent or harmful effects of the agent may occur." (pg 49) Risk Assessment The term risk assessment refers to "a process for identifying adverse consequences and their associated probability." Risk assessment is " the process of determining risks to health attributable to environmental or other hazards." Risk assessment provides a qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (pg 59) Risk (Dreaded and Unknown) (See pg 59) Hazard A hazard is defined as the "inherent capability of an agent or a situation to have an adverse effect. A factor or expo-sure that may adversely affect health." 4 Hazards may originate from chemicals, biological agents, physical and mechanical energy and force, and psycho-social influences. (pg 59)

Describe how water is made safe for human consumption:

Water supplied to the public in the United States undergoes treatment in order to meet quality standards set by the EPA for safe levels of chemical contaminants and waterborne microorganisms. As noted previously, water sources include surface water (lakes and reservoirs) and water from aquifers. Processing of water takes place in water treatment plants, an example of which is shown in Figure 9-9. The four stages of water treatment in most plants are as follows: coagulation, sedimentation, filtration, and disinfection. These stages are presented in Figure 9-10. As shown in Figure 9-11, after untreated water flows from a storage area into the plant, it first undergoes coagulation to remove suspended material. Aluminum sulfate is used as the coagulating agent. After the coagulating agent has been mixed with the water, the mixture is transferred to sedimentation tanks similar to the ones shown in Figure 9-12. The water then is filtered to remove smaller impurities. The filter is made of progressively finer layers of sand and a layer of activated charcoal. Subsequently, the water is treated with a disinfectant such as chlorine to destroy pathogens. (pg 216) See pg 217 for chart

Discuss the health effects of exposure to ionizing and non-ionizing radiation:

ionizing ---The amount of radiation dose that is absorbed—expressed as either grays or rads—may or may not be associated with acute health effects, depending upon individual susceptibility and amount of exposure as determined by the foregoing factors. The health effects of radiation exposure are described as nonstochastic and stochastic (acute) effects. pg 183

State the differences between ionizing and non-ionizing radiation:

ionizing ---used to kill cancer cells, and in many manufacturing processes." 1 Sources of ionizing radiation include those decaying radioactive materials that emit alpha and beta particles and gamma rays, medical pro-cedures that employ radiopharmaceuticals and devices such as X-ray machines, and bodies in outer space that contribute to the earth's background radiation. non-ionzing radiation is used to ../Other examples include radio frequency energy (e.g., radiation from radio antennas), optical and ultraviolet radiation (e.g., from the sun), infrared (heat) radiation, and low-frequency radiation (e.g., radiation from electric power lines). Potential health effects of exposure to nonionizing radiation range from annoyance to acute symptoms such as pain and swelling to se-rious eye injury and long-term consequences such as cancer. pg 177