Section 1
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Stage 3 of Demographic Transition:
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Date created
Mar 1, 2020
Cards (146)
Section 1
(50 cards)
Stage 3 of Demographic Transition:
each subset of population is a similar percentage of total population
Subacute/Chronic Toxicity
Prolonged exposure to a toxicant → could be life threatening in long term organ system effects and cancer are endpoints → difficult to distinguish effects from other influences & to diagnose and treat
LD50:
Lethal dose that kills 50% of the study population → dosage is measured in weight of toxicant per body weight of subject (mg toxicant/kg body weight): used to measure/ assess toxicity
Environmental Risk Transition
Changes in the environmental risks that happen due to economic development in the less developed regions of the world
Dose-Repsonse Curve
Graph used to describe the effect of exposure to a chemical or toxic substance upon an organism such as an experimental animal. diff for indv/ pop.
Toxin
A toxic substance made by living organisms
Problem with Animal studies
Tend to not simulate real world → very specific information, gives us some ideas and direction to follow for future but usually high dose exposure requiring extrapolation
25% of all deaths/diseases can be attributed to
environmental factors
Epidemiologic transition
Shift in pattern of morbidity & mortality: Infectious diseases → chronic diseases
Cohort studies (Observational)
Classify participants based on exposure status and observe them over time, prospective & retrospective. +good for identifying multiple outcomes - poor for identifying multiple exposures
Clinical Trial (Experimental)
The investigator will assign people to treatment group or control group. Follow up to compare outcomes + for identifying outcomes based on one exposure + for controlling confounding
Healthy worker effect:
a type of selection bias; employed people tend to have lower mortality than general population → any excess mortality associated with a given occupational exposure is more difficult to detect when the healthy worker effect is operative → workers are more likely to be healthy than the general population
Incidence
# of NEW Cases of Disease / Total # of People at Risk during a given period of time: probability someone develops a disease, causality b/w exposure + disease demonstrated, and evaluate effectiveness of preventative disease programs.
Threshold on the dose-response curve:
Point where giving another dose results in nothing happening!
The Policy Cycle
def//formulation/reformulation -> agenda setting -> policy est. -> policy implementations -> assessment ->
Toxicology Experimental Methods
Highly controlled experiments, usually in lab setting using animals
Toxicant
Toxic substances that are manmade
Case Fatality Rate
Number of deaths due to a disease / number of cases of a disease
Recall Bias
People with a disease may be more likely to recall and exposure than ppl without
Prevalence
# of EXISTING cases of a disease / Total # of people in a population at a given point in time: assess variation in disease occurence
Synergism
Response is greater than expected: co-synergy (enhancing), potentiation (1 nontoxic causes a chemical to become more toxic), and coalitive (2 agents w/ no observed toxicity produce toxic effecT)
Descriptive epi
(SURVEILLANCE) track & compare disease rates in populations across place and time → describe disease cases by their demographic characteristics → looks for clustering (who/where/how a pop is affected by a disease) as evidence of an environmental exposure
Antagonism
Response is less than expected. Can be physiological, chemical, disposition, or receptor.
Environmental epi
focuses on the study of diseases linked to environmental exposures/hazards → focuses on factors beyond a person's control
Xenobiotic
Chemicals foreign to the biologic system, includes natural occurring subtances, drugs, etc.
Limitations of Epi STUDY
Long Latency Periods (lag time b/w exposre + dev. of disease), Low Incidence and Prevalence (w/ uncommon diseases, difficult to find associations w/ exposures: small n), Recall Bias (people with disease may be more likely to recall an exposure than ppl. w/o a disease), difficulties in Exposure Assessment
Epidemiology
The study of the distribution and determinants of disease frequency in human populations . . . and the application of this study to control health problems; "population medicine"
Case Series (Observational)
info about patients who share a disease in common is gathered over time → useful for developing hypotheses for future study → weakest type of study for making causal assertions
Polluter Pays Principle
Polluter should bear expenses of carrying out pollution prevention and control
Environmental justice
Low-income minorities should not be subjected to more toxins → children of color are exposed to more toxins
Environmental Sustainability:
Resources should not be depleted faster than regenerated and no permanent natural env. Changes
Analytic epi:
(Epi RESEARCH/Studies), Document link between exposure and disease. What/why are the reasons for distribution of disease?
Long Latency Periods
time lag b/w exposure and the development of a disease --> once the disease develops, it may be difficult or impossible to go back and measure the exposure.
Difficulties in exposure assessment
Accuracy, misclassification, chemical mixture exposures, monitoring low-level env. exposures, lack of indv. exposure measurements
Low Incidence and Prevalence
when diseases are uncommon, it is difficult to find associations with exposures (small sample size)
Acute toxicity
Single exposure to a toxicant → poisoning/life-threatening event. Diagnosed & Treatments or Antidotes available.
Types of joint interactions of chemical mixtures:
Antagonism Additivity Synergism
Routes of absorption:
Ingestion in GI tract Inhalation through lungs Intravenous/dermal through blood and lymph
Stage 3 of Demographic Transition
Each subset of population is a similar percentage of total population
Additivity
Response is as expected: exposure (dose) and effect (response)
Ecological Studies (Observational)
Evaluated an association between disease and exposure on the population level. - Ecological Fallacy: unknown if people with disease are the same people that have been exposed. +Good for looking at ass. and generating hyp.'s.
Cross-sectional studies (Observational)
Assess both exposure and outcome at the same point in time --> -Unable to tell which came first & -not good for testing or generating hypotheses
Toxicology Epi Methods
Observations on uncontrolled populations, usually in the natural environment
ED50:
Effective dose that produces the desired effect in 50% of the population
Precautionary principle
Err on side of caution, even if cause-and-effect has not been established
Toxicology Goal
To understand the causal relationships between toxicant exposure (biological, chemical, physical, or biological) and adverse human health effects & ecosystem
Goal of Environmental Policy
Reduce human risks or env. damages resulting from pollution/ env. hazards
dose-response relationship
Type of corr. relationship b/w the "characteristics of exposure to a chemical and the spectrum of effects cause by the chemical"
For causality, look for:
-Association is observed consistently -A given disease results from a given exposure and not from other types of exposures -Must observe exposure before disease -Higher exposure means higher disease incidence Exposure → disease must be biologically plausible -Cause-and-effect should not conflict with generally known facts
Total fertility rate
Hypothetical amount of births a woman would have by end of her reproductive life
Section 2
(50 cards)
Organochlorines
Chlorinated / hydrocarbon-based. Includes DDT → binds to insects' nerve cells → accumulation of DDT inside birds' tissue results in fragile egg shells
Rodenticide
A chemical or agent used to destroy rats or other rodent pests, or to prevent them from damaging food, crops, etc.
The Rise of Superweeds
Weed species often become resistant to herbicides. Glysophate resistance rose after genetically engineered crops were introduced in the mid 1990's
Role of Environmental Health in Emergency Preparedness
To ensure that the vulnerable areas of our env. are protected from accidental or intentional contamination
Dipyridyl compounds
Type of herbicide → lead to skin/pulmonary effects and PD
Atrazine:
Most commonly detected pesticide in US drinking water → binds to ETC in chloroplassts →Pyrethrins: natural insecticidal extract a common weed killer → the amount of atrazine in drinking water spikes during the summer → plants die of starvation and oxidative damage
Agent Orange
A defoliant used during Vietnam War to prevent thick jungle foliage from concealing the enemy
Nonionizing radiation:
has enough energy to excite, but not eject, electrons → induces currents and excites electrons Ex.'s) AM/FM radio, microwave, infrared, visible light, electrical power lines, extremely low frequency (ELF) radiation
Sources of Lead
Lead was added to gasoline, paint, mining, used in commercial/industrial operations. Soil may have high levels. Enters dust or air in businesses and mines or smelters may contaminate nearby soil or water.
Settled dust from 9/11
Harmful compounds produced by the burning jet fuel Barium, dioxins, lead: (50% non fibrous material, 40% glass and fibers, 9.2% cellulose, and 0.8% abestos) & (61.5% larger than 53 microns: morel likely to become lodged in upper airways of lungs) Effects on responders, rescuers, office work: res. symptoms, sinus problems, asthma, loss of lung functions, sarcoidosis, heartburn, PTSD, acid reflux
Vector control:
Zika, WNV, post-disaster control (dog/snake bites) Zika transmission: a mosquito will often live in only a single home during its lifetime (pass disease between all people there) Zika virus can be passed from mom to fetus -> birth defects Sex, blood transfusions 80% of people with Zika will have no symptoms Conjunctivitis, joint/muscle pain, fever, rash, etc.
Pyrethrins
natural insecticidal extract
Carbamates
Salts or esters of carbamic acid
Dioxins
result from combustion/chemical manufacturing → bind tightly to soil → persistent organic pollutants that biomagnify in the food chain
RI lead lawsuit:
paint companies' paint poisoned thousands of RI kids
How Zika spreads
Mosquito bites and sexual transmission
Effects of Lead Exposure in adults:
could lead to reproductive/pregnancy issues, thyroid problems
Major Toxic Metals
not necessary to sustain life. Toxic at both acute/chronic levels. Ex.'s are Arsenic, beryllium, lead, mercury, nickel.
Fungicide
substance that kills fungi or inhibits their growth. acute dermatitis → chronic dermatitis/cancerPyrethrins: natural insecticidal extract
Pyrethroids
synthetic derivatives → used to control West Nile Virus and for aircraft "disinfection"
Metals and Medicine
Metals used for medical therapy. Ex.'s) Aluminum, Lithium, and Platinum
Lead is Released from teeth and bones into the bloodstream during times of bodily stress such as
pregnancy, breastfeeding, calcium deficiency, and osteoporosis
Organophosphates (anticholinesterases)
Organic esters of phosphoric acid
Human exposure to Metals: Soil/Dust
mining/smelting. Ingestion mainly by babies (lead paint chips)
Emergency Preparedness (vision of Fed. Emergency Management Agency FEMA)
Encouraging individuals, govt. entities, and public and private groups @ all levels to become informed of the risks they face, make decisions that help keep people, property, and institutions out of harm's way, and to possess the capability and knowledge needed to act when disasters occur.
Human exposure to metals: Air
mainly occupational, smelting/mining/blast furnaces
Avg. radiation exposure to radiation workers, fed a state limit
5000 millirem/ year
Fumigant
A pesticide vaporized to kill pests
ChE-inhibitors
Insecticides that block the normal breakdown of acetylcholine Cause nausea, diarrhea, sweating, wheezing, urination
Herbicides
chemicals to control or destroy plants, weeds, or grass
Hurricane Harvey
Plants leaking chemicals into floodwaters Mold exposures A dozen sewage overflows containing vibrio vulnificus/ flesh eating disease Inoperable wastewater facilities People subject to active boil water notices Vector control
Three ways to classify metals
Major Toxic Metals, Essential Metals, Metals and Medicine
Essential metals
Essential for life at trace amounts, but have the potential for toxicity at high concentrations. Ex.'s) Iron (accumulates in the body: little is excreted), Copper, Manganese, Zinc.
Herbicides/Defoliants
Mixed structure; often hormone derived
Ionizing radiation:
radiation with enough energy to eject electrons from atoms, creating ions → occurs naturally → damages DNA Ex.'s UV X Rays
Soil may have high lead content due to
Pre-1976 leaded gasoline
Gamma Ray or X-Ray (Ionizing Radiation)
High energy photon → have no mass or charge
Effects of Lead Exposure on young children
Learning disabilities, impaired hearing, anemia, decreased growth, lowered IQ
Lead Hazard Mitigation Law in RI (2002):
Tried to prevent childhood lead poisoning → safer rental housing → landlords complain about these additional expenses → say that there are no kids at their property, so why do they have to comply Low compliance because there is no enforcement of the law
Exposure to Lead
Ingestion in children, inhalation of lead dust → but, most kids are exposed to lead through inhalation
Insecticide
used to kill insects
Pesticides
Substances or mixtures intended for preventing, destroying, repelling or mitigating any pest. ALSO any substance or mixture intended for use as a plant, regulator, defoliant or desciant.
Flint Water Crisis: lead came from
Water treatment plant Corrosive pipes Lead in tap water Service lines (pipes connecting water mains and individual homes)
Alpha particle (Ionizing Radiation)
helium nucleus (2 protons and 2 neutrons)
Four routes of human exposure to metals
Air , Soil/dust , Water, rust from pipes, old pipes, Biota
Beta Particle (Ionizing Radiation)
An energetic electron → much less massive than an alpha particle
Avg. occupational radiation exposure to all personnel (not handling radioactive material) limit
< 100 millirem/ year
Classes of Pesticides
Organophosphates Carbamates Herbicides/defoliants Organochlorines
Human Exposure to Metals: Biota
biomagnification (mercury in fish), pesticides released into water and then enter fish
Human exposure to Metals: Water
well water (arsenic), rust from pipes (Iron), old pipes (Lead)
Section 3
(46 cards)