chapter 17 Flashcards
to study for the test (dec 4)
risk
measure of the likelihood of suffering harm from a hazard
- expressed in terms of probability
risk assessment
the scientific process of using statistical methods to estimate how much harm a particular hazard can cause to human health or to the environment.
- mathematical probability statement about how likely it is that harm will result from a hazard
risk management
deciding whether or how to
- reduce a particular risk to a certain level
- at what cost
four major types of hazards
biological, chemical, physical, cultural
biological hazards (examples)
pathogens, bacteria, viruses, parasites, protozoa, fungi
chemical hazards (examples)
harmful chemicals in air, water, soil, food
physical hazards (examples)
earthquakes, volcanic eruptions, flooding, tornado, hurricane
cultural hazards (examples)
smoking, poor diet, drugs, alcohol, driving, criminal assault, poverty, unsafe working conditions, unsafe sex
poison
a chemical that has an LD50 of 50mg or less per kg of body weight
median lethal dose
aka LD50
the amount of chemical received in one dose that kills exactly 50% of subjects in a test population
non-transmissible disease
aka noncommunicable disease
are not caused by living organisms, do not spread from person to person
e.g. cancer, diabetes, asthma, malnutrition
transmissible disease
aka communicable disease
caused by a living organism or a virus, can spread from one person to another
e.g. covid-19, flu virus, common cold
pathogen
infectious agents that spread through air, water, food, bodily fluids, insects, and vectors
bioterrorism
the deliberate release of disease-causing bacteria or viruses into the air, water, or food of concentrated urban populations
with the aim of eradication of the inhabitants
factors for antibiotic-resistant bacteria
- human travel/trade spreads resistant bacteria across the globe (pandemics)
- overuse of antibiotics; facilitated purchase of antibiotics w/o a perscription
- bacteria can transfer resistance to nonresistant bacteria
- widespread use of antibiotics in livestock and dairy animals
factors for tuberculosis
- many do not know they’ve been infected; lack of screening/control programmes
- people are close together; increased population growth & urbanisation; air travel
- genetically resistant strains of tb to almost all effective antibiotics
- spread of other diseases weakens the immune system & allows tb to spread more easily
flu
biggest killer of all transmissible diseases (except tuberculosis)
about 1mil deaths per year
combatting hiv/aids
2nd most deaths by transmissible disease
- reduce the number of new infections below the number of deaths.
- provide hiv testing for people in high-risk groups (truck drivers, sex workers, soldiers)
- concentrate on those most likely to spread the disease
malaria
- killed more people than all wars
- caused by a parasite spread by mosquitoes
- cases have been increasing due to mosquito species becoming genetically resistant to most insecticides; best prevention method is to control the spread
steps to reduce cases of infectious disease
- immunise people early on
- oral rehydration therapy to replace water in victims of diarrheal diseases (majority children under 5)
- invest more money into preventing infectious diseases in developing countries
factors for increased rates of infectious disease
- human activities: farming, air travel, urbanisation
- infectious diseases are transmitted from wild and domesticated animals to humans (e.g. avain flu, sars, west nile, lyme disease)
- clearing & fragmentation of forests exposes humans to new types of infectious disease
ecological/conservation medicine
new field of research devoted to tracking down infectious connections between wildlife and humans
hazardous chemicals
flammable, explosive, irritating/damaging to skin and lungs, interfere with oxygen uptake, induce allergic reactions
mutagens
cause or increase random mutations in dna
- no safe threshold for exposure to harmful mutagens
teratogens
literally “monster makers”
chemicals that cause harm to fetus/embryo; cause birth defects
e.g. alcohol, thalidomide
carcinogen
chemicals that cause/promote cancer
immune system
specialised cells & tissues that protect the body against disease & harmful substances
- forms antibodies that attack invading agents
nervous system
consists of the brain, spinal cord, peripheral nerves
neurotoxins
a poison that specifically attacks the nervous system
endocrine system
glandular system that releases hormones into the bloodstream
hormonally active agents (haa)
can mimic hormones
- can disrupt: human immune functions, endocrine/nervous systems, reproductive & growth/developmental processes, thyroid function (growth, weight, brain, behavioural disorders)
- promote cancer
bhopal, india
1984
- world’s worst industrial accident
- explosion of underground storage tank released highly toxic MIC gas
- MIC gas was converted to deadly hydrogen cyanide
factors determining harm caused by exposure to chemicals
- amount of exposure (dose)
- frequency of exposure
- affected person’s medical/biological processes (genetic makeup, effectiveness of body’s detox system)
toxicity
measures how harmful a substance is in causing injury, illness, or death
five major factors affecting the amount of harm caused by a substance
- solubility
- persistence
- bioaccumulation
- biomagnification
- chemical interactions/reactions
solubility
- affects the amount of harm caused by a substance
- high solubility means the chemical can move through the environment more easily
- fat- and oil-soluble toxins can accumulate in an organism
persistence
- affects the amount of harm caused by a substance
- chemicals may resist breakdown & remain in the environment for a long time
- may have long-lasting effects
bioaccumulation
- affects the amount of harm caused by a substance
- molecules that are absorbed can be stored in the body at higher levels with each dose
biomagnification
- affects the amount of harm caused by a substance
- toxins accumulate at greater levels as they move up tophic levels
chemical interactions/reactions
- affects the amount of harm caused by a substance
- antagonistic interaction: reduces harmful effects of toxins
- synergistic interaction: enhances harmful effects
acute vs chronic effect
- acute: immediate reaction to a toxin
- chronic: long-lasting consequence from exposure to a harmful substance
basic concept of toxicology
any synthetic or natural chemical can be harmful if ingested in a large enough quantity
three major bodily mechanisms for reducing harmful effects of chemicals
- break down, dilute, or excrete toxins; keeps them from reaching harmful levels
- enzymes can repair damaged dna & protein molecules
- cells can reproduce fast enough to replace damaged cells
poverty
- greatest risk, in terms of premature deaths per year & reduced life span
- reducing poverty would improve human rights, provide more people with income (stimulating economic development), reduce environmental degredation, reduce threat of terrorism
factors for difficulty in determining risk for complex tech
- unpredictability of human behaviour
- human error
- sabotage
- chance events
system reliability (equation)
% = [tech reliability] * [human reliability]
ionising radiation
- in the form of x-rays
- radiation from nuclear sources
- uv radiation from the sun/sun lamps
minamata disease
- neurological effects from mercury poisoning
- 1956, minamata, japan
- mercury from industrial wastewater bioaccumulated in fish & shellfish
epidemiological transition (phases 1-5)
- phase 1: high death rates due to epidemics, famine, war
- phase 2: less frequent epidemics, medical advances =dropping death rates
- phase 3: levelling off of death rate, nontransmissible disease associated with aging is majority of death toll
- phase 4: level death rate, imedical advances leads to increasing average life span
- phase 5: urbanisation & overuse of antibiotics/pesticides leads to increase in death rate due to re-emergence of new infectious diseases
factors that impact the sense of evaluating risk
- degree of control over situation
- fear of the unknown
- conditions of the situation; voluntary risks vs forced risks
- unfair distribution of risks
factors for poor risk evaluation
- misinformation
- denial; confirmation bias
- irrational fears/phobias
