EHS590 Midterm Study Flashcards

These are the flashcards for Module 1 EHS90 Midterm Exam. Date: October 5 2023

Disability Adjusted Life Years (DALYs)

Sum of years of life lost due to premature death + years with disability

Approximately what percentage of DALYs are attributable to environmental factors?

20%

3 MULTIPLE CHOICE OPTIONS

3 Ps - Major Determinants of Environmental Health

(1) Population

(2) Poverty

(3) Pollution

Toxicology

The study of adverse effects of chemical, physical or biological agents on people, animals and the environment. Identify at what level of exposure and through what exposure route they may become hazardous.

Environmental Health

the branch of public health that addresses physical, chemical, biological, social and psychosocial factors in the environment

Which of the following factors has been the most significant contributor to this population growth?

Improved nutrition & basic sanitation

3 MULTIPLE CHOICE OPTIONS

Demographic transition model (DTM)

a model that describes population change over time

DTM Stage 1

High stationary stage:

-high birth & death rates (young population)

-population stable/slow growth (~1%)

DTM Stage 2

Early Expanding Stage:

-high birth & decreasing mortality rates (young population)

-population growing rapidly

DTM Stage 3

Late Expanding Stage:

-decreasing birth & mortality rates (more uniform age distribution)

-population still grows b/c birth rates are higher than death rates

DTM Stages 4-5

Low stationary & Declining Stages:

-low birth & mortality rates, population remains stable/declining

demographic transition

Shift from high birth and mortality rates in underdeveloped societies to lower fertility and lower mortality rates as a result of development

world population growth is currently...

growing population, decreasing growth rate

3 MULTIPLE CHOICE OPTIONS

limitation of DTM

Model does not consider migration and how it may effect population

3 MULTIPLE CHOICE OPTIONS

which is most strongly associated with total fertility rate (TFR)?

avg. female education

3 MULTIPLE CHOICE OPTIONS

epidemiologic transition

a shift in morbidity and mortality patterns from communicable diseases (CD) to non-communicable diseases (NCD)

environmental health effects of urbanization

-increases exposures to pollutants & pathogens

environmental risk transition

the process by which traditional communities with associated environmental health issues become more economically developed and experience new health issues

World Health Organization (WHO)

Organization: Mission is to advocate and catalyze global and country actions to resolve the human resources for health crisis

3 MULTIPLE CHOICE OPTIONS

U.S. Environmental Protection Agency (EPA)

Organization: Mission is to protect human health and the environment.

3 MULTIPLE CHOICE OPTIONS

National Center for Environmental Health(NCEH)/Agency for Toxic Substances & Disease Registry (ATSDR) - U.S. CDC

plans, directs, and coordinates a program to protect the American people from environmental hazards.

3 MULTIPLE CHOICE OPTIONS

National Institute for Environmental Health Sciences(NIEHS) - U.S. NIH

Mission is to discover how the environment affects people, in order to promote healthier lives.

3 MULTIPLE CHOICE OPTIONS

4 Principles of Developing Environmental Health Policies

1. Precautionary principle

2. Environmental justice

3. Environmental sustainability

4. Polluter-Pays principle

Polluter-Pays principle

Polluters bear the expense of carrying out pollution prevention & control & necessary remediation measures to ensure that the environment is in an acceptable state

Environmental justice goal

everyone enjoys:

-the same degree of protection from environmental and health hazards

-equal access to the decision making process to have a healthy environment in which to live, learn, and work.

precautionary principle

preventive, anticipatory measures applied when weight of evidence suggests possibility of adverse health consequences

poison

any agent capable of producing a deleterious response in a biological system

3 MULTIPLE CHOICE OPTIONS

Toxic agent

Material or factor that can be harmful to biological systems

3 MULTIPLE CHOICE OPTIONS

Toxin

Toxic substance made by living organisms including reptiles, insects, plants and microorganisms

3 MULTIPLE CHOICE OPTIONS

Toxicant

Toxic substances that are man-made or result from human activity

3 MULTIPLE CHOICE OPTIONS

Toxicity

Degree to which an agent is poisonous

3 MULTIPLE CHOICE OPTIONS

Areas of Toxicology

-Regulatory

-Forensic

-Clinical

-Reproductive

-Developmental

-Genetic

-Environmental

Ebers Papyrus (1500 BC)

Egyptian 20 m scroll with 700 drugs in 900 formulas

Paracelsus

Known as the "Father of Toxicology"

-Formulated many revolutionary views that remain an integral part of Toxicology and Pharmacology today

Mathieu Orfila

Known as the "Father of Forensic Toxicology"

-the 1st toxicologist to use autopsy material and chemical analysis systematically as legal proof of poisoning

exposure dose

the amount of a substance encountered in the environment

external dose

a dose acquired by contact w/ contaminated environmental sources

absorbed dose

the amount of a substance that is available to internal organs of the body

internal dose

the portion of a substance that becomes internalized in the body through ingestion, absorption, and other means

administered dose

the quantity of a substance that is administered

biologically effective dose

the portion of the internal dose that is required to cause a health outcome

total dose

the dosage acquired by adding together all the individual doses

how is dose often expressed?

- μg/ml of blood

- mg/kg of body weight

3 MULTIPLE CHOICE OPTIONS

LD50

The lethal dose of a substance that kills 50% of the exposed population (mg/kg body weight). Determines based on a single acute exposure in test animals

LD50/30

the dose that kills 50% within 30 days

LD50/60

the dose that kills 50% within 60 days

true or false. All substances can be toxic

true

1 MULTIPLE CHOICE OPTION

LD50 uses

➢ compare the acute toxicities of chemicals

➢ classify chemicals by poisoning potential

➢ identify target organs

➢ provide dose-ranging guidance for other studies

LD50 limitations

does not reflect the full spectrum of toxicity of the substance or predict delayed effects

dose-response relationship

Quantitatively describes the association between exposure to a compound and the effects produced by that exposure

A pharmaceutical is non-toxic if...

ED50 is lower than TD50

3 MULTIPLE CHOICE OPTIONS

dose-response models

-Linear Non-Threshold (LNT) model

-Threshold model

-Hormetic (U-Shaped) model

Hormesis

Adverse effects observed at very low doses (deficiency) or high doses (toxicity), while moderate doses are beneficial

Linear Non-Threshold (LNT)

dose response model

Threshold model

dose response model (non-carcinogens)

Hormetic model

U-shaped dose-response relationship in which cancer rates decline at very low doses of a carcinogen and then begin to rise as the dose is further increased

Reference Dose (RfD)

A dose that does not cause adverse effects.

Formula = NOAEL or LOAEL / UF(s) x MF

Factors influencing toxicity of an agent

-route of exposure

-absorption, distribution, metabolism, & excretion (ADME)

-duration of exposure

-interactions among chemicals

individual susceptibility

Major routes of exposure

inhalation, ingestion, dermal contact, intravenous injection (IV)

ADME

Absorption (A)

Distribution (D)

Metabolism (M)

Excretion (E)

Duration of exposure

Acute, subacute, subchronic, chronic

Acute exposure duration

usually a single exposure for less than 24h

Subacute exposure duration

exposure for 1 month or less

Subchronic exposure duration

exposure for 1-3 months

Chronic exposure duration

exposure for more than 3 months

Additive Effect

the combined effect of the two chemicals is equal to the sum of the effects of each agent given alone. (most common) 2+2=4

Hyponatremia

water intoxication

Synergistic Effect

occurs when the combined effects of two chemicals are much greater than the sum of the effects of each agent given alone. 2+2=20

Potentiation

occurs when one compound does not have a toxic effect on a certain organ or system but when added to another chemical makes that chemical much more toxic. 0+2=10

Antagonism

occurs when two chemicals administered together interfere with each other's action or one interferes with the action of the other. (4 types) (-2) + 2 =0

trace elements

elements required by an organism in only minute quantities

Cancer risk formula

Cancer = Cancer slope factor x exposure

Carcinogens Group 1

carcinogenic to humans

Carcinogens Group 2A

probably carcinogenic

Carcinogenic Group 2B

possibly carcinogenic to humans

Carcinogenic Group 3

not classifiable as to carcinogenicity to humans

UF

Uncertainty factor

MF

Modifying factor

NOAEL

No Observed Adverse Effect Level

LOAEL

Lowest Observed Adverse Effect Level

individual susceptibility

• Genetic polymorphisms: Single nucleotide polymorphisms (SNPs) in metabolism genes, DNA repair genes

Epigenetic changes:– Methylation (suppresses protein translation)– Acetylation (enhances protein translation)

• Health and Nutritional status:– Availability of amino acids/trace elements necessary for detoxification pathways

• Gender

• Age

Methods for testing for toxicity

- in vitro

- in vivo

-Ames Assay (in vitro)

Ames Assay

"Gold standard" method for determination of mutagenic activity of test agents (most widely used)

2 MULTIPLE CHOICE OPTIONS

In vivo testing

Animals exposed purposely. "Gold standard" method for determination of carcinogenic powers of test agents.

2 MULTIPLE CHOICE OPTIONS

In vitro testing

Cells derived from humans, animals, yeast or bacteria used to screen for different toxic properties of test agents

2 MULTIPLE CHOICE OPTIONS

risk assessment

A process of determining risks to health attributable to environmental and other hazards.

'Red Book'

1. Hazard identification

2. Dose-response assessment

3. Exposure assessment

4. Risk characterization

risk assessment objectives

1. Balance risk and benefits

2. Set target levels of risk

3. Set priorities for program activities

4. Estimate residual risk and extent of risk reduction after steps are taken to reduce risk

epidemiology

Study of distribution, patterns, and determinants of health and disease in human populations

disease measures of epidemiology

prevalence and incidence

environmental epidemiology

The study of environmental health effects from involuntary exposure to the human body

prevalence

# existing cases/total population (at a point in time)

- Important for: hypothesis generation, policy decisions, budget preparation, resource allocation

incidence

CI = # new cases/total population at risk (during span of time)

IR = # new cases/total person-time of observation

- Important for: Describing risk in a population, Necessary for establishing causality, Predicting future events

epidemiology study designs

- Descriptive studies

- Ecologic (correlational) studies

- Analytical (etiologic) studies

Descriptive studies

describe patterns in disease occurrence in terms of demographic and other variables

Ecologic studies

assesses overall frequency of disease in a series of populations and looks for a correlation with the average exposure in the populations.

Major limitation of ecologic studies

critically limited by ecological fallacy

Analytical studies

clinical trials (controlled experiments), observational studies (cohort studies, case-controlled studies, cross-sectional studies)

Cohort studies (analytical)

- Seek to replicate an experiment using observational data

- Provide risk/rate ratios to estimate associations between exposure and disease

*estimates true risk

Risk Ratio (P, CI, IR)

risk in exposed group/risk in unexposed group

Case-controlled studies (analytical)

*hypothesis-testing studies

- Provide odds ratios (OR) - odds for exposure

- Start with an diseased (cases) and non-diseased (controls) groups and look backwards in time to determine the odds of exposures in each group