Module 6 Flashcards
1
Q
define environmental toxicant
A
a chemical that is released into the environment and that can produce adverse health effects on living organisms
2
Q
Acute Toxicity
A
a single exposure to a chemical and often large dose of the chemical (ex. spill)
3
Q
chronic toxicity
A
generally associated with repeated exposure to a small doses of a chemical over a long period of time (contaminated food)
4
Q
Toxic Effects of Aflatoxin B1
A
-acute and chronic present different
-actue can result in liver necrosis, failure and death
-chronic can cause liver cancer
5
Q
common food contaminant in southeast asia and central africa
A
Aflatoxin B1
6
Q
foods containing Aflatoxin B1
A
corn, peanuts, groundnuts
7
Q
three common sources of toxiants
A
- Air pollution
- Tobacco smoke
- Pesticides
8
Q
Air pollution
A
-divided into 2 main categories
1. particulate matter
2. gaseous air
**attributed to both natural and anthropogenic sources
9
Q
air pollution in 1273
A
first air pollution law established by Edward I, King of England. He made it illegal to burn coal while parliament was in session, punishment was decapitation
10
Q
air pollution in 1900s
A
-first automobiles were manufactured, & within decades, millions of vehicles
-gasoline internal combustion engines became (& still are) a major source of air pollution
11
Q
air pollution in 1952
A
-“killer smog” in London responsible for an estimated 4000 deaths
-main causes of death were bronchitis, pneumonia, and other respiratory illness
-demonstrated lethality of air pollution and led to the Clean Air Act
12
Q
History of Air Pollution in 1956
A
-the clean air act introduced a number of measures to reduce air pollution
-one was to shift source of home-heated towards cleaner coals, eletiricity, and gas, reducing smoke from fireplaces
13
Q
two general categories of air pollutants
A
-particulate matter
-gaseous air pollutants
14
Q
particulate matter
A
mixture of tiny particles composed of non-gaseous pollutants (biological materials)
**can be solid or liquid
15
Q
gaseous air pollutants
A
some major ones are CO2, carbon monoxide, nitrogen oxides, sulfur oxides, hyfrogen sulfide and ozone
16
Q
Natural air pollutants
A
volcanoes, forrest and prarie fires and dust storms
17
Q
Anthropogenic air pollutants
A
-man made air pollutants
-three main sources:
1. Heating and power
2. automobiles
3. Industrial processes
18
Q
heating and power
A
combusting fossil fuels releases CO2, CO, Sulfur oxides, and nitrogen oxides
**coal is largest contributor to human-made increase of CO2 in air
19
Q
Automobiles
A
-exhaust releases smoke ,lead particles, CO and Nitrogen oxides
-in late 20th century, governmental regulations forced decrease of emissions with use of low or unleaded gas
-recently, emission testing and green vehicles gave helped reduce impact of emissions
20
Q
INdustrial processes
A
-types depend on manufacturing process
-ex. acids, solvents, chlorine and ammonia gas, and metals
21
Q
Human health and air pollutants
A
- predominant health effect is chemical irritation of the respiratory tract
22
Q
populations susceptible health effects of air pollution
A
young children, older adults, people with cardiorespiratory disease (asthma)
23
Q
health problems of air pollution are due to
A
combined action of particulates and sulfur oxides, but no signle pollutant seems to be responsible
24
Q
environmental/second hand tobacco smoke is
A
the combination of mainstream smoke (exhaled) and sidestream smoke (burning end)
25
Research on second hand smoke exposure
-in 2002 international agency for research cancer concluded the exposure to second hand smoke can cause lung cancer
26
Health risks of second hand smoke
-exposure to evironmental smoke carries same risk as directly smoking
-bylaws try to deter this
27
Pesticides
-unique because used to intentiaionally kill organisms
-two major classes:
1. Insecticides
2. Herbicides
28
Insecticides
-chemicals used to kill isects/make it so they are unable to reproduce or develop normally
29
organochlorine insecticides
-work by increasing sensitivity of neurons, resulting in increased CNS stimulation that manifests as death
-cna present long term problems in humans that are not fully understood
ex. DDT
30
DDT
- introduced in 1945 to control malaria-containing mosquitoes
-effective and used until 1970
- stopped use b/c insecs developing resistance, bird and fish decreased, soil and water DDT levels increasing and amnt in food was increasing
31
organophosphorus insecticides
-first synthesized during world war II to be used as potential warfare agents
-selectively developed that requires metabolic activation to work
-occurs rapidly in insects
-relatively unstable and break down environment
-overall considered to have small impact on environment
32
organophosphoprus toxicity
- very toxic to humans
- absorbed through skin and leading cause of poisoning in agricultural sector
33
mechanism of action organophosphorus
irreversibly inhibit AchE, that is responsible for breaking dow AcH in the synaptic cleft
34
effects of organophosphorus toxicity
-if AchE is inhibited, AcH in the tissue increases
-this results in increased neuronal firing resulting in decreased HR, difficulty breathing, fecal and urinary incontinence, and blurred vision or death from respiratory failure
35
Herbicides
-chemicals capable of killing or injuring plants
-two examples: agent orange and paraquat
36
Agent orange
-used in vietnam war as defoliant to spot targets hidden by tree cover
-acts by mimicking plant growth hormones, causing uncontrolled growth leading to plant death
37
major concern of agent orange
presence of a chemical called TCDD, introduced during manufacturing
38
Agent orange (TCDD ) toxicity
-TCDD bonds aryl hydrocarbon receptor, involved in expression of genes for cell fucntioning
-TCDD toxicity manifests as chloracne
-impairment of liver and CNS function too
-associated with increased occurrence of certain cancers and may cause birth defecits/stillbirths
39
Chloracne
skin disorder that is severe form of acne, can resolve in years or be permanent
40
when did YTCDD poisoning make the news
-in 2004 after ukranian president became ill
-he was jaundiced, bloated and has chloracne
-blood serum levels 50,000 times more than general population
-poisoned at a dinner after controversial election
41
Paraquat
-one of most widely used
-highly toxic when ingested
-causes cellular damage and when ingested, causes immediate burns to mouth and stomach
42
where does paraquat target
-the lungs
-cellular damage results in developmetn of fibrous tissue that inhibits ability to breathe
-two teaspoons can cause death due to lung damage
43
3 common specific chemicals that produce toxic effects
1. Lead
2. Mercury
3. Bisphenol A
44
Lead
- ubiquitous, naturally ocurring element found in the environemnt and many diff chemical compounds
45
two main compounds containing lead
1. lead oxide
2. Tetraethyl lead
46
Lead exposure sources
1. old paint
2. Industry
3. Leaded gasoline
47
lead in old paint
-lead used to make paint dry quicker in 1950's
-problematic for young children
48
ingested lead in children vs adults
adults absorb 10% ingested, children absorb 35-50% ingested
49
Lead exposure in industry
-lead-acid car batteries account for most significant proportion of global lead consumption
-industries that use lead release lead emissions into air
-some can end up in soil adn contaminate food
50
Leaded gasloine exposure
-until 1970 tetraethyl lead was used as additive to gas to increase engine compression
-during combustion lead was oxidized and released to atmosphere
-even tho gas is now mainly unleaded, this is still persistent as lead is used in aviation of fuel
51
Lead toxicity symptoms
-CNS
-PNS
-Kidneys
-Blood
52
CNS lead toxicity
-initial symptoms present as decrease in appetite, irritability, and fatigue
-lead to permanent brain damage, resutling learning defivits, epilepsy, and blindness
53
PNS lead toxicity
-degeneration of motor nerves
-loss of coordination and appearance of clumsy
54
Lead toxicity in kidneys
- impairment of energy metabolism involving mitochondria within kidney
-effects are reversible if exposure stops
55
blood lead toxicity
-decreases biosynthesis of heme, an iron-containing component of hemoglobin, leading to decreased lifespam of RBC
-anemia
-effect is reversible if source removed
56
where can mercury be found
water or air
57
main contamination source of mercury
industry, where it is used in preparation of chlorine and sodium hydroxide as electrode
58
mercury exposure
in the air where it exists as water vapour or in food
59
main source of mercury exposure
humans ingesting fish from mercury contaminated waterand is concentrated through the food chain
60
two toxic forms of mercury
mercuric mercury and methyl mercury
61
mercuric mercury
-exposure occurs through inhalation of vapours containing mercury
-only 15% of mercuric mercury is absorbed but it accumulates is kidneys
62
Methyl Mercury
-converted via bacteria and fish
-most toxic form
-90% absorbed from food
-targets CNS, blinds nerve cell proteins and leads to nerve cell death
-acute toxicity results in irritability, numbness, tingling, vision and hearing loss and paralyiss
-chronic toxicity can lead to coma and death
63
Treatment for Mercury toxicity
-chelating agents not effective for methyl mercury poisoning but are for mercuric mercury poisoning
-methyl mercury cna be treated with charcoal if recently ingested but has no effect on already absorbed mercury
**can be irreversible
64
Minimata disease
name given to resulting sickness of mercury poisoning to those living in japan
-from contaminated water
-methyl mercury poisoning
65
Lead common exposure sources
- old paint
-car batteries
-exhaust fumes
66
mercury common exposure sources
- seafood
67
lead toxicity symptoms
-appetite loss
-coordination loss
-kidney damage
-anemia
68
mercury common toxicity sympotoms
-nerve cell death
-tingling
-vision/hearing loss
69
Lead treatment
chelating agents like EDTA
70
mercury treatment
-activated charcoal
-chelating agents
71
Bisphenol A
-industrial chemcial used to make hard, clear plastic known as polycarbonate
72
main source of exposure to BPA
-through diet where minute quantities can leach out of containers and into water or food, and this increases with heating
73
MoA BPA
has estrogen-like activity, meaning it can bind estrogen receptors and mimic some effects of estrogen. Synthetically derrived estrogen cmpds (BPA) could play a role in reproductive cancers, fertility problems and altered brain development in infants
74
Health Canada statement on BPA
current dietary exposure is not expected to pose a health risk to general population
75
BPA toxicity to children
-newborns and infants at greatest risk of exposure
-government banned sale of baby bottles containing BPA
76
environmental BPA toxicity
-BPA in bodies of water may harm fish, and other organisms
-as precautionary measure, environmental canada has proposed regulations to limit concentration of BPA that can be released
77
adverse effects of pharmaceuticals in the environement
-well known
78
predcting adverse effects of pharmaceuticals
possible to predict adverse effecrts of pharmacuticals in drinking water on humans but hard to predict the effects on aquatic animals and plants
79
Six ways pharmaceuticals enter the envrionement
1. Use in agriculture
2. treatment of pets
3. Disposal of medication
4. aquaculture
5. human prescription
6. manufacturing process
80
pharmaceutical use in agricultre
-primarily responsible for the increased levels of antibiotics in groundwater and soils
--used to treat animals, agent is excreted and resulting manure is spread as fertilizer
81
Pharmaceutical treatment of pets
peta metabolize and excrete pharmaceuticals as do humans and will find their way into surface and groundwater
82
disposal of medication
-25% of all unused drugs are washed down sink or flushed down toilet, finding way into sewage discharge
-30% all unused drugs are out into garbage/disposed in landfiill which can contaminate groundwater
83
aquaculture
anibiotics used to prevent disease and promote rapid growth and maturity and high local concentrations exist
84
Human prescriptions
-one of major sources of pharmaceuticals in environment
-a percent f drugs are excreted unchanged or as active metabolites & passed to municipal waste systems
-treatment may not remove pharmaceuticals prior to entry of sewage to environment
85
Manufacturing Process
-discharge from plants have major effect on local surface groundwater
-will increase over time as chemical facilities move to less developing countries with less standards
86
5 major classes of pharmaceuticals in the environement
1. Neuroactive Drugs
2. Steroid Hormones
3. Antibiotics
4. Antihypertensive Drugs
5. Analgesics
87
exmaples of Neruroactive Drugs
antiepileptics, antideprtessants, SSRIs, and antipsychotics
88
Neuroactive drugs prevalence
use has increase over 60% in last decade
89
where have neuroactive drugs been detected
water, groundwater , soils
90
sweage treatment plants and neuroactive drugs
reduce but do not effectively remove this group of drugs
91
exposure of neuroactive drugs in the environement
minimal, but SSRIs in waters have had deleterious effects on the reproduction and psychological development of fish
92
Steroid Hormones
-the ones of most concern are estrogenic compounds
-sources of estrogen include ethinyl estradiol from oral contraceptives and excretion of natural estrogens from plants and animals
93
current concentrations of steriod hormones n the environemnt
well below where effects would be observed
94
two major concerns wth steroid hormones in the environment
1. Additive effect
2. Reproduction and Maturation
95
additive effect of steriod hormones in the environment
additive effects of human exposure to estrogens and endocrine disrupting agents (BPA)
96
Reproductiona nd maturation concern with steriod hormone sin the environment
deleterious effect of low concentrations of steroid hormones on the reporductive capacity and sexual maturation of aquatic animals
97
why may use of antibitoics in agriculture be a concern to human health?
can result in the development of resistance strains of bacteria to human infections
**another concern is biomagnification of antibiotics in edible plants and animals leading to low level exposure of antibiotics to humans
98
Antihypertensive drugs
-30% of canadians take drugs for hypertension
-low level of concentration in surface water
-but are these biomagnified in the food chain???
99
what are analgesics
pain relieving medication
100
what are the most commonly found analgesics in the environment
ibprofen, naproxen & ASA due to high frequency of use
101
analgesics and human health
concentrations in drinking water do not pose risk to human health
102
analgesics and aquatic species
acute toxicity of analgesics in environment appears to be minimal on aquatic species
103
two potential sources of human exposure to pharmaceuticals in the environment
drinking water and bioaccumulation in food sources
104
the concentration of a pharmaceutical in the environment is a function of a number of factors such as:
-extent of use
-dose administered
-persistence
-ability of sewage treatment to remove agent
105
what is used for determining the risk of various concentrations of a pharmaceutical in the environemnt to humans?
minimal therapeutic dose
106
high fold difference between daily exposure and minimal therapeutic dose means
no effects on human health
107
what group of drugs does the minimum therapeutic dose risk assessment fail
anticancer drugs
108
ways to reduce potential of pharmaceuticals in the environment
- reduce dischage from factories
-drug licensing process
-destroy pharmaceuticals in wastewater prior to discharge
-expanding take back programs for proper disposal
109
what organisms is at greatese risk of pharmaceuticals in environment
fish
110
what is caner and what is the prevlanece of cancer
-a group of diseases that primarily affects Canadians 50+
-45% of males and 43% of females will develop cancer (1 in every 2.3 ppl)
-30% of all deaths due to cancer
111
common types of cancer in canada
lung, breast, colorectal, prostate (lung cancer leading cause)
112
cancer
a generic term for a large number of diseases that involve abnormal groups of cells
113
cell growth and division
the ability to proliferate indefinitely
114
Invasion
ability to invade surrounding normal tissue
115
Metastasis
ability to spread throughout the body
116
2 main interacting causes of cancer
genetics and environmental factors
117
genetics causing cancer
-genetic makeup cotributes to a variation in response to carcinogens
-ex speople with XP have genetically-based deficiency in DNA repair and prone to mutations (high incidence of cancer)
118
environmental factors causing cancer
-include non-genetic elements such as chemicals, diet, and infections
-these factors are modifiable meaning a person can decrease risk of exposure to detrimental environmental factors
119
four common environmental cancers that influence cancer risk
tobacco use, adult diet, occupational factors & viruses
120
tobacco use
-smoking may cause cancer
-whether smoking results in the development of cancer will depend upon the tar content, frequency, and duration
121
how much more likely is smokers to develop cancer than non smokers
eight times
122
is passsive smoking a risk factor for cancer
yes
123
adult diet and cancer
-saturated animal fat and red meat are strongly linked to cancer of colon, rectum and prostate
-high salt intake linked to stomach and other cancer
-thought that fruits and veggies contain constituents that block cancer-inducing chemicals produced in the body
124
Occupational factors contributing to cancer
exposure to carcinogens
125
common carcinogic hazards in the workplace
-asbestos
-benzene
-formaldehyde
-ionizing radiation
-soot
126
asbestos
-lung cancer
-workers: brane-lining, shipyard, insulation, demolitian
127
Benzene
-Leukemia
-workers: painters, furniture finishers, rubber workers, petrochemical workers
128
Formaldehyde
-nose cancer
-hospital/lab workers, manufacturers of wood products, paper and texiles
129
Ionizing radiation
-bone marrow
-nuclear material workers, medicinal product and procedure workers
130
Soot
-skin cancer
-workers: chimney sweeps, firefighters, bricklayers
131
Viruses & infection
-bacterial and viral infections linked to cancer
132
Bacteria & cancer
helicobacer pylori, a bacterium responsible for causing stomach ulcers, stongly associated with stomach cancer
133
viruses and cancer
-hep B & C can cause liver cancer
-estimated that globally up to 80% of liver cancer is caused by hepatitis
-HPV, which is sexually transmitted can cause cervical cancer
134
what are types and incidence of cancer differ depending on the country, why?
based on food consumed, access to vaccines, and regulatory measures
135
measures that can be taken to reduce cancer risk
-avoid excessive sunlight
-monitor alcohol intake
-eliminate tobacco use
-eat healthy
-be active
-get vaccinated
136
avoiding excessive sunlight for preventing cancer
- decreases risk of skin cancer
137
Monitoring alcohol intake to prevent cancer
-alcohol is associated with a number of cancers including mouth, and liver
138
eliminating tobacco use to reduce risk of cancer
greatly decreases risk of developing lung cancer and other cancers
139
eating health to reduce cancer risk
maintaining adequate diet of fruit and veggies and moderating consumption of saturated fats and red meats
140
being active to reduce cancer risk
maintining healthy lifestyle will ensure your body is in its best form to combat the carcinogens exposed t on daily basis
141
getting vaccinated to reduce cancer risk
Hep B can cause liver cancer, while HPV can cause cervical cancer
142
Preventing cancer
this is the goal when treatment is given to prevent cancer cell growth to remove precancerous cells that could turn into cancer
143
Curing cancer
primary goal of treatment however a cure has only been acheived for few cancers (testicular, Hodgkins and childhood lukemia)
144
Controling the cancer
when cure is not possible, the goal is to stop it from growing and spreading and prolonging patient survival
145
Relieving symptoms of cancer
when curing or controlling is not possible, this can include medications for controlling symptoms like nausea & pain
146
treatment types of cancer
surgery, chemo, radiotherapy, and immunotherapy
147
what do chemotherapeutic drugs do
slwo the growth of rapidly dividing cells,by inhibiting DNA synthesis, protein synthesis or cell division
148
four classes of drugs used as chemotherapies
1. Alkylating agents
2. Mitotic inhibitors
3. Hormones & hormone antagonists
4. biologicals
149
Alkylating agents
bind to and interfere with DNA replication
150
Mitotic Inhibitors
affect microtubule function and the formation of the mitotic spindle, thereby preventing cell division
151
Hormones and hormone antagonists
used to treat hormone sensitive tumours by suppressing cell division
152
Biologicals
inhibit cell replication by blocking cytokines, which normally control cell growth (some drugs are also antibodies to these cytokines)
153
How do chemotherapeutics utilize the concept of selective toxicity to target cencer cells?
cancer cells divide continuously, whereas normal cells are in a nondividing state therefore one way to target cancer cells is to target continuously dividing cells
154
factors to consider when designing a cancer chemotherapy regimine
1. Benefit-risk assessment
2. Combination chemotherapy
155
Benefit risk assessment
-weigh benefits versus adverse effects
-ex. targeting continuously dividing cells will also harm hair cells, GI cells, resulting in nausea, vomiting, and ulceration
-each type of cancer is also associated with own toxicities
156
Combination chemotherapy
-chemotherapeutic drugs frequently used in combination b/c:
1. Development of resistance is lower
2. Occurence of toxicities; b/c chemotheraeutic drugs have LOW therapeutic indexes if a single one was used, it might not be possible to increase dose
157
what are modifiable factors that cause most cancer death
tobacco and nutrition
