Chapter 14 Environmetal Health And Toxicology Flashcards

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1
Q

What is toxicology?

A

The study of chemical hazards and the effects of poisonous substances on humans and other organisms.

Toxicologists assess and compare substances to determine their toxicity.

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2
Q

What is a toxicant?

A

A toxic substance, or poison, that can inflict harm if ingested or exposed to in sufficient quantities.

Any chemical substance may exert negative impacts if the quantity is large enough.

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3
Q

Complete the phrase: ‘The dose makes the _______’

A

poison

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4
Q

What does environmental toxicology focus on?

A

Toxic substances that come from or are discharged into the environment.

Toxicologists generally focus on human health, using other organisms as models.

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5
Q

What are the leading indoor hazards that contribute to lung cancer?

A

Cigarette smoke and radon.

These are the top two causes of lung cancer in developed nations.

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6
Q

What is radon?

A

A highly toxic radioactive gas that is colorless and undetectable without specialized kits.

Radon seeps up from the ground in certain areas and can accumulate indoors.

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7
Q

What health issues can result from long-term exposure to asbestos?

A

Scarring of lung tissue, impaired lung function, and asbestosis.

Asbestos is dangerous when inhaled.

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8
Q

What are the effects of lead poisoning?

A

Damage to the brain, liver, kidney, and stomach; learning problems; anemia; hearing loss; and even death.

Lead poisoning among U.S. children has greatly declined due to educational campaigns.

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9
Q

What are PBDEs?

A

Polybrominated diphenyl ethers, chemicals used as fire retardants in various consumer products.

PBDEs persist and accumulate in living tissue and have been linked to health issues.

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10
Q

What concerns are associated with PBDEs?

A

They act as hormone disruptors and may affect thyroid hormones, brain development, and potentially cause cancer.

Studies have shown increasing concentrations of PBDEs in breast milk.

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11
Q

True or False: The European Union banned PBDEs in 2003.

A

True

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12
Q

What has been the trend of PBDE concentrations in the United States compared to Europe?

A

Rising concentrations in the U.S. with little movement to address the issue, unlike Europe where concentrations have fallen substantially.

The dangers posed by PBDEs have raised questions about flammability standards.

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13
Q

FAQ

A
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14
Q

Do individual organisms

A
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15
Q

survive exposure to a toxic

A
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16
Q

chemical because they are

A
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17
Q

“mutated” by the chemical

A
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18
Q

and develop defenses to the

A
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19
Q

toxicant?

A
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20
Q

When a population of organisms

A
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21
Q

is exposed to a toxicant

A

such as

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22
Q

a pesticide

A

a few individuals often

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23
Q

survive while the vast majority

A
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24
Q

of the population is killed. These

A
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25
Q

individuals survive because they

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26
Q

already possess genes (which

A
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27
Q

others in the population do

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28
Q

not) that code for enzymes that

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29
Q

counteract the toxic properties of

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30
Q

the toxicant. Because the effects

A
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31
Q

of these genes are expressed only

A
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32
Q

when the pesticide is applied

A
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33
Q

many people think the toxicant

A
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34
Q

“creates” detoxification genes by

A
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35
Q

mutating the DNA of a small num-

A
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36
Q

ber of individuals. This is not the

A
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37
Q

case. The genes for detoxifying

A
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38
Q

enzymes were present in the DNA

A
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39
Q

of resistant individuals from birth

A
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40
Q

but their effects were seen only

A
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41
Q

when pesticide exposure caused

A
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42
Q

selective pressure (p. 50) for

A
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43
Q

resistance to the toxic substance.

A
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44
Q

Sensitivity also can vary with sex

A

age

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45
Q

of their smaller size and rapidly developing organ systems

A
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46
Q

younger organisms (for example

A

fetuses

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47
Q

children tend to be much more

A
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48
Q

sensitive to toxicants than are

A
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49
Q

adults. Regulatory agencies such

A
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50
Q

as the U.S. Environmental Pro-

A
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51
Q

tection Agency (EPA) typically

A
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52
Q

set human chemical exposure

A
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53
Q

standards for adults and extrapo-

A
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54
Q

late downward for infants and

A
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55
Q

children. However

A

many sci-

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56
Q

entists contend that these linear

A
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57
Q

extrapolations often do not offer

A
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58
Q

adequate protection to fetuses

A
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59
Q

infants

A

and children.

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60
Q

The type of

A
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61
Q

exposure can

A
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62
Q

affect the

A
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63
Q

response

A
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64
Q

The risk posed by a hazard often

A
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65
Q

varies according to whether a per-

A
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66
Q

son experiences high exposure for

A
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67
Q

short periods of time

A

known as

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68
Q

acute exposure

A

or low exposure

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69
Q

over long periods of time

A

known

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70
Q

as chronic exposure. Incidences

A
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71
Q

of acute exposure are easier to

A
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72
Q

recognize

A

because they often

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73
Q

stem from discrete events

A

such as

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74
Q

accidental ingestion

A

an oil spill

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75
Q

chemical spill

A

or a nuclear acci-

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76
Q

dent. Toxicity tests in laboratories

A
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77
Q

generally reflect acute toxicity

A
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78
Q

effects. However

A

chronic expo-

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79
Q

sure is more common-and more difficult to detect and diag-

A
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80
Q

nose. Chronic exposure often affects organs gradually

A

as when

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81
Q

smoking causes lung cancer or when alcohol abuse leads to

A
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82
Q

liver or kidney damage. Arsenic in drinking water or pesticide

A
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83
Q

residues on food also pose chronic risk. Because of the long

A
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84
Q

time periods involved

A

relationships between cause and effect

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85
Q

may not be readily apparent.

A
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86
Q

species

A

however

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87
Q

abundant. Cascading impacts can cause changes in the composi:.

A
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88
Q

bunof the biological community (p. 53g) and threaten ecosystem.

A
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89
Q

functioning. There are many ways toxicants can concentrate and

A
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90
Q

persist in ecosystems and affect ecosystem services.

A
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91
Q

Airborne substances can travel widely

A
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92
Q

Toxic substances are released around the world from agricul.

A
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93
Q

tural

A

industrial

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94
Q

be redistributed by air currents (Chapter 17)

A

exerting impacts

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95
Q

on ecosystems far from their site of release.

A
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96
Q

Because so many substances are carried by the wind

A
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97
Q

synthetic chemicals are ubiquitous worldwide

A

even in seem.

98
Q

ingly pristine areas. Scientists who travel to the most remote

A
99
Q

alpine lakes in the wilderness of British Columbia find them

A
100
Q

contaminated with industrial toxicants

A

such as polychlorinated

101
Q

biphenyls (PCBs)

A

which are by-products of chemicals used in

102
Q

transformers and other electrical equipment and as hydraulic

A
103
Q

fluids. These chemicals enter the air

A

soil

104
Q

equipment in which they are housed burns

A

leaks

105
Q

Earth’s polar regions are particularly contaminated

A

because

106
Q

natural patterns of global atmospheric circulation (p. 451) tend

A
107
Q

to move airborne chemicals toward the poles (FIGURE 14.12).

A
108
Q

Thus

A

although we manufacture and apply synthetic substances

109
Q

At high latitudes

A
110
Q

deposition of pollutants

A
111
Q

exceeds evaporation

A
112
Q

2 Pollutants are

A
113
Q

transported by

A
114
Q

atmosphere and

A
115
Q

ocean currents

A
116
Q

Atmospheric currents

A
117
Q

Evaporation

A
118
Q

Pollutants enter

A
119
Q

the polar food

A
120
Q

web and

A
121
Q

accumulate in

A
122
Q

biota

A
123
Q

Deposition

A
124
Q

— North Pole

A
125
Q

Evaporation

A
126
Q

Deposition

A
127
Q

At low

A
128
Q

latitudes

A
129
Q

evapora-

A
130
Q

tion of

A
131
Q

pollutants

A
132
Q

exceeds

A
133
Q

deposition

A
134
Q

Oceanic currents

A
135
Q

Toxic Substances and Their

A
136
Q

Effects on Ecosystems

A
137
Q

When toxicants concentrate in environments and harm the health

A
138
Q

of many individuals

A

populations (p. 48) of the affected spe-

139
Q

cies become smaller. This decline in population can then affect

A
140
Q

other species. For instance

A

species that are prey of the organ-

141
Q

ism affected by toxicants could experience population growth

A
142
Q

because predation levels are lower. Predators of the poisoned

A
143
Q

Equator

A
144
Q

FIGURE 14.12 Air and water currents direct pollutants to the

A
145
Q

poles

A

In the process of “global distillation

146
Q

What are the main categories of products that can introduce toxicants into the environment?

A

Consumer products, Workplace products, Medicines and materials

These categories highlight the various sources of potential environmental toxins.

147
Q

What are the primary environmental mediums through which toxicants travel?

A

Soil, Water (surface and groundwater), Air

These mediums are critical for understanding the distribution of toxic substances.

148
Q

Which groups are particularly sensitive to toxicants?

A

Developing fetuses, Babies

These groups are more vulnerable to the effects of toxic substances due to their developmental stages.

149
Q

What is pesticide drift?

A

The process by which pesticides are carried by air currents to sites far from agricultural fields

This phenomenon can have ecological impacts far from the source of pesticide application.

150
Q

What environmental effect is associated with pesticide drift in the Sierra Nevada?

A

Population declines in four species of frogs

This illustrates the ecological consequences of pesticide use and drift.

151
Q

How do toxic substances concentrate in water?

A

Water running off from land transports toxicants and concentrates them in small volumes of surface water

This process highlights the importance of runoff in water quality issues.

152
Q

What role do wastewater treatment plants play in water contamination?

A

They add toxins, pharmaceuticals, and detoxification products from humans to waterways

This contributes to the overall toxic load in aquatic systems.

153
Q

What happens to chemicals that persist in soil?

A

They can leach into groundwater and contaminate drinking water supplies

This emphasizes the long-term impacts of soil contamination on water quality.

154
Q

True or False: Contaminants are evenly distributed in the environment.

A

False

Toxic substances are not evenly distributed and may concentrate in specific areas.

155
Q

What is a significant concern regarding the concentration of contaminants in polar regions?

A

Contaminants are strikingly concentrated in the tissues of Arctic polar bears, Antarctic penguins, and people living in Greenland

This raises concerns about bioaccumulation and its effects on wildlife and human health.

156
Q

Fill in the blank: Humans receive small amounts of toxicants from many sources, including _______.

A

[Consumer products, Workplace exposure, Medical facilities, Drinking water, Air for breathing]

These sources contribute to the overall exposure of humans to toxic substances.

157
Q

What type of animals are effective indicators of pollution?

A

Aquatic animals such as fish, frogs, and stream invertebrates

These animals are sensitive to low concentrations of pollutants and reflect water quality.

158
Q

What factors influence the degradation rate of toxic substances in the environment?

A

Chemistry, temperature, moisture, and sun exposure

The degradation rate varies based on these environmental conditions.

159
Q

What is the persistence time of Bt toxin compared to DDT and PCBs?

A

Bt toxin has a very short persistence time, whereas DDT and PCBs persist for decades

Bt toxin is used in biocontrol and genetically modified crops.

160
Q

What is bioaccumulation?

A

The process where toxic substances accumulate in an organism’s body

This occurs when substances are absorbed and stored in tissues.

161
Q

Fill in the blank: Toxic substances that bioaccumulate may be transferred to other organisms through _______.

A

biomagnification

162
Q

What happens to the concentration of toxicants as they move up the food chain?

A

Concentrations become magnified

Each predator accumulates toxicants from multiple prey, increasing concentration.

163
Q

What was the effect of DDT on North American birds of prey from the 1950s to the 1970s?

A

Populations declined precipitously

DDT caused eggshells to grow thinner, leading to embryo death.

164
Q

What are breakdown products?

A

Simpler compounds into which most toxicants degrade

These may be less harmful or just as toxic as the original substance.

165
Q

True or False: Atrazine has a consistent persistence time regardless of environmental conditions.

A

False

Atrazine’s persistence is highly variable based on environmental factors.

166
Q

What is the relationship between fat-soluble substances and their storage in organisms?

A

They are absorbed and stored in fatty tissues

This includes organic compounds like DDT and DDE.

167
Q

What notable environmental success occurred after the ban of DDT in the United States?

A

Populations of birds of prey rebounded

Species like the peregrine falcon and bald eagle saw recovery after DDT was banned.

168
Q

What is the primary reason synthetic chemicals are designed to persist in the environment?

A

To resist breakdown

This characteristic is beneficial for materials like plastics.

169
Q

What is the impact of toxic substances entering the water supply?

A

They can affect human health and ecosystems

Contaminants enter drinking water and air, posing risks to all living organisms.

170
Q

Fill in the blank: DDT breaks down into ________, which is a highly persistent and toxic compound.

A

DDE

171
Q

What is the process of toxic substances accumulating in an individual’s tissues called?

A

Bioaccumulation

172
Q

What happens during biomagnification in a food web?

A

Toxicants are passed up the food chain, increasing in concentration

Each predator accumulates toxins from multiple prey.

173
Q

Unfortunately

A

DDT continues to impair wildlife in parts

174
Q

of the world where it is still used. In addition

A

mercury bioac-

175
Q

cumulates in some commercially important fish species

A

such

176
Q

as tuna. Polar bears of Svalbard Island in Arctic Norway show

A
177
Q

extremely high levels of PCB contamination from biomag-

A
178
Q

nification as a result of the global distillation process shown

A
179
Q

in Figure 14.12. Polar bear cubs suffer immune suppression

A
180
Q

hormone disruption

A

and high mortality- and because the

181
Q

cubs receive PCBs in their mothers’ milk

A

contamination per-

182
Q

sists and accumulates across generations.

A
183
Q

In all these cases

A

biomagnification affects ecosystem

184
Q

composition and functioning. When populations of top preda-

A
185
Q

tors such as eagles or polar bears are reduced

A

species interac-

186
Q

tions (PP. 74-78) change

A

and effects cascade through food

187
Q

webs (p. 80).

A
188
Q

Toxic substances can threaten

A
189
Q

ecosystem services

A
190
Q

Toxicants can alter the biological composition of ecosystems

A
191
Q

and the manner in which organisms interact with one another

A
192
Q

and their environment. In so doing

A

harmful compounds can

193
Q

threaten the ecosystem services (pp. 4

A

116) provided by nature.

194
Q

For example

A

pesticide exposure has been implicated as a fac-

195
Q

tor in the recent declines in honeybee populations (pp. 245-

A
196
Q

246)

A

affecting the ecosystem service of pollination they

197
Q

provide to wild plants and agricultural crops.

A
198
Q

Nutrient cycling is one of the many services that healthy

A
199
Q

functioning ecosystems provide. Decomposers and detri-

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200
Q

tivores in the soil (p. 78) break down organic matter and

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201
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replenish soils with nutrients for plants to use. When soils are

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202
Q

exposed to pesticides or antifungal agents

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nutrient cycling

203
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rates are altered. This can make nutrients less available to

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204
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producers

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affecting their growth and causing impacts that

205
Q

cascade throughout the ecosystem.

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206
Q

Studying Effects of Hazards

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207
Q

Determining health effects of particular environmental haz-

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208
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ards is a challenging job

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especially because any given person

209
Q

or organism has a complex history of exposure to many haz-

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210
Q

ards throughout life. Scientists rely on several different meth-

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211
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ods with people and with wildlife

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ranging from correlative

212
Q

surveys to manipulative experiments (p. 13).

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213
Q

Wildlife studies integrate work

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214
Q

in the field and lab

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215
Q

Scientists study the impacts of environmental hazards on

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216
Q

wild animals to help conserve animal populations and also to

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217
Q

understand potential risks to people. Just as placing canaries

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218
Q

in coal mines helped miners determine whether the air was

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219
Q

safe for them to breathe

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studying how wild animals respond

220
Q

to pollution and other hazards can help us detect environmen-

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221
Q

tal health threats before they do us too much harm.

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222
Q

Often wildlife toxicologists work in the field with ani-

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223
Q

mals to take measurements

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document patterns

224
Q

hypotheses

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before heading to the laboratory to run con-

225
Q

trolled manipulative experiments to test their hypotheses.

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226
Q

The work of two of the pioneers in the study of endocrine

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227
Q

disruptors illustrates the approaches embraced in wildlife

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228
Q

Biologist Louis Guillette studied alligators in Florida

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229
Q

(FIGURE 14.15a) and discovered that many showed bizarre

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230
Q

reproductive problems. Females had trouble producing viable

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231
Q

eggs

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young alligators had abnormal gonads

232
Q

lings had too little of the male sex hormone testosterone while

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233
Q

female hatchlings had too much of the female sex hormone

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234
Q

(a) Louis Guillette taking blood sample from alligator

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235
Q

(b) Tyrone Hayes in lab with frog

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236
Q

FIGURE 14.15 Wildlife studies examine the effects of toxic substances in the environment. Researchers

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237
Q

Louis Guillette (a) and Tyrone Hayes (b) found that alligators and frogs

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respectively

238
Q

maities that they attribute to endocrine disruption by pesticides.

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239
Q

CHAPTER 14 Environmental Health and Toxicology

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240
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369

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