Two types of cell death
apoptosis: programmed cell death
necrosis: cell damage and death<\/p>\n\n\n\n
Virus vs bacteria
virus: only active within host cells which they need to reproduce
bacteria: single-celled organisms that produce own energy and can reproduce on their own<\/p>\n\n\n\n
DNA base pairing
A-T
G-C<\/p>\n\n\n\n
DNA strands held together by\u2026
hydrogen bonds<\/p>\n\n\n\n
DNA to protein
DNA encodes the sequence of proteins carried in DNA<\/p>\n\n\n\n
Gene
DNA coding (for protein, for trait)<\/p>\n\n\n\n
Protein functions
structural support, storage, transport, cellular communications, movement, and defense against foreign substances<\/p>\n\n\n\n
Protein sequence
determines how protein will fold<\/p>\n\n\n\n
Protein structure
determines function<\/p>\n\n\n\n
Enzyme
enhances rate of chemical reaction in body; catalysts, so not used up in reaction<\/p>\n\n\n\n
Process of DNA to protein
DNA > transcription > RNA > transcription > protein<\/p>\n\n\n\n
Genome
all of an organism’s genetic material<\/p>\n\n\n\n
Epigenetics
the study of influences on gene expression that occur without a DNA change<\/p>\n\n\n\n
determines which genes are expressed<\/p>\n\n\n\n
Epigenetics results in
heritable changes in the phenotype without changes to DNA sequence\/structure (genotype)<\/p>\n\n\n\n
Can epigenetic modifications be transferred from generation to generation?
YES<\/p>\n\n\n\n
Three mechanisms of epigenetics<\/p>\n\n\n\n
DNA methylation
adding a methyl group to DNA to switch off the gene<\/p>\n\n\n\n
possible connection between DNA methylation of 5 genes and PM 2.5<\/p>\n\n\n\n
Histone
protein molecule around which DNA is tightly coiled in chromatin<\/p>\n\n\n\n
Histone modification
changes in the structure of histones that make it more or less likely that a segment of DNA will be transcribed<\/p>\n\n\n\n
acetyl group allows for transcription<\/p>\n\n\n\n
Epigenetic factor that binds to histone tail
acetyl group; allows for transcription<\/p>\n\n\n\n
Micro-RNAs
bind to complementary RNA to prevent translation<\/p>\n\n\n\n
Mutation
heritable changes in genetic information
genotype change<\/p>\n\n\n\n
Microlesions
base pair substitution<\/p>\n\n\n\n
2 types of microlesions
change in DNA sequence
change in codon (if coding region)<\/p>\n\n\n\n
Change in codon – 3 outcomes
no effect = degenerate code<\/p>\n\n\n\n
missense mutation = change amino acid, sometimes function<\/p>\n\n\n\n
nonsense mutation = premature termination or splice change<\/p>\n\n\n\n
Types of genetic mutations in lecture
microlesions
frameshift mutations
macro lesions<\/p>\n\n\n\n
Types of genetic mutations<\/p>\n\n\n\n
frameshift mutation
mutation that shifts the “reading” frame of the genetic message by inserting or deleting a nucleotide<\/p>\n\n\n\n
consequences: altered protein, often non-functional<\/p>\n\n\n\n
macrolesions
chromosomal aberrations<\/p>\n\n\n\n
change in chromosomal structure<\/p>\n\n\n\n
change in chromosome number<\/p>\n\n\n\n
Cause of chromosomal aberration
effects on mitotic machinery, not DNA<\/p>\n\n\n\n
Macrolesion mutation: change in chromosome structure
deletion, duplication, inversion, translocation — usually cell death<\/p>\n\n\n\n
Macrolesion mutation: change in chromosome number
aneuploidy: increase number of one+ chromosomes<\/p>\n\n\n\n
polyploidy: increase in whole set<\/p>\n\n\n\n
Aneuploidy
A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.<\/p>\n\n\n\n
Polyploidy
condition in which an organism has extra sets of chromosomes<\/p>\n\n\n\n
polymorphism
the individual differences of form among the members of a species<\/p>\n\n\n\n
can change function of proteins<\/p>\n\n\n\n
Health effects of mutation
germ cells\/ova: point mutations may be lethal
somatic cells: source of variability (polymorphism); concern = carcinogenesis<\/p>\n\n\n\n
How does cancer arise?
DNA mutations in cells
uncontrolled proliferation<\/p>\n\n\n\n
Proto-oncogene mutation
leads to altered forms of normal cellular genes<\/p>\n\n\n\n
tumor supressor gene
mutation
can promote apoptosis
can act as “brake” to regulate proliferation of normal cells<\/p>\n\n\n\n
Genotoxic compounds
directly alter DNA
point mutations
chromosomal aberrations<\/p>\n\n\n\n
point mutation
gene mutation in which a single base pair in DNA has been changed<\/p>\n\n\n\n
nongenotoxic compound
do not directly alter DNA but can increase cancer risk<\/p>\n\n\n\n
increase chance of replication errors and increase number of cells at risk<\/p>\n\n\n\n
cancer types with highest mortality in US
women: lung, breast, colon<\/p>\n\n\n\n
men: lung, prostate, colon<\/p>\n\n\n\n
innate immunity<\/p>\n\n\n\n
physical barriers help prevent entry<\/p>\n\n\n\n
0-12 hours after infection — immediate<\/p>\n\n\n\n
adaptive immunity<\/p>\n\n\n\n
detects molecules (usually proteins) on surface of cells and learns to ignore self proteins<\/p>\n\n\n\n
delayed<\/p>\n\n\n\n
non-self proteins
antigens, substance that can promote immune response<\/p>\n\n\n\n
what type of cell makes antibodies?
B lymphocytes<\/p>\n\n\n\n
can there be multiple antigens on one pathogen?
YES<\/p>\n\n\n\n
antigen
a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies<\/p>\n\n\n\n
antibody
a substance produced by the body that destroys or inactivates an antigen that has entered the body<\/p>\n\n\n\n
Antigen reaction<\/p>\n\n\n\n
basophils and mast cells
release chemicals that mediate inflammation and allergic responses<\/p>\n\n\n\n
neutrophils
ingest and destroy invaders<\/p>\n\n\n\n
eosinophils
destroy invaders, especially antibody coated parasites<\/p>\n\n\n\n
monocytes and macrophages
ingest and destroy invaders, antigen presentation<\/p>\n\n\n\n
dendritic cells
recognize pathogen and activate other immune cells by antigen presentation<\/p>\n\n\n\n
antigen-presenting cells<\/p>\n\n\n\n
natural killer cells (NK cells)
pursue diseased cells<\/p>\n\n\n\n
How vaccines work<\/p>\n\n\n\n
goal of immunization
produce memory of vaccine antigen via large population of memory cells<\/p>\n\n\n\n
first-pass effect (hepatic first pass)
some drugs dont enter systemic circulation immediately following oral absorption but pass from the intestinal lumen to the liver by the portal vein<\/p>\n\n\n\n
drug goes to liver first<\/p>\n\n\n\n
Role of liver in digestion
regulates metabolism of the macronutrients, stores some nutrients (glycogen), and produces bile<\/p>\n\n\n\n
response to toxicant influenced by\u2026
differences in pharmacokinetics and pharmacodynamics due to species\/strain, sex, age, disease, and enzyme induction (prior exposure)<\/p>\n\n\n\n
enzyme induction
the increase in hepatic enzyme activity that results in greater metabolism of drugs<\/p>\n\n\n\n
2 basic functions of toxicology<\/p>\n\n\n\n
mechanistic study
answers “How does this system work?”<\/p>\n\n\n\n
study of potential modes of action in lab animals (in vivo) or tissues, cells, etc (in vitro)<\/p>\n\n\n\n
in vivo studies in tox
ADME studies
effect of different dosing levels<\/p>\n\n\n\n
in vitro studies in tox
mutagenic potential
molecular mechanisms of action<\/p>\n\n\n\n
strengths and weaknesses of mechanistic studies
strengths: compound-specific information, cross-species extrapolation, dose extrapolation<\/p>\n\n\n\n
weaknesses: difficult to rule out alt theories; often lack data for humans<\/p>\n\n\n\n
dose-effect relationship
the relationship between drug dose and blood, or other biological fluid concentrations<\/p>\n\n\n\n
dose-response relationship
the relationship between the different doses and the responses they generate<\/p>\n\n\n\n
how is toxicity quantified?
dose-effect and dose-response relationships<\/p>\n\n\n\n
LD50
the point at which 50 percent of the test organisms die from a toxin<\/p>\n\n\n\n
lethal dose in mg\/kg<\/p>\n\n\n\n
used to compare relative acute toxicity<\/p>\n\n\n\n
LC50
concentration of a substance needed to kill 50% of the organisms within a specified period of time<\/p>\n\n\n\n
lethal concentration in ppm or mass\/volume<\/p>\n\n\n\n
ADD
average daily dose<\/p>\n\n\n\n
ADD formula
C x IR \/ BW = average daily dose in mg\/kg\/day<\/p>\n\n\n\n
C= concentration
IR= intake rate
BW= body weight<\/p>\n\n\n\n
NOAEL and LOAEL
No Observed Adverse Effect Level
Lowest Observed Adverse Effect Level<\/p>\n\n\n\n
CSF
cancer slope factor<\/p>\n\n\n\n
0.10\/LED10<\/p>\n\n\n\n
provides estimate of increase in cancer risk per mg\/kg\/day of ADD<\/p>\n\n\n\n
rise and run in CSF
rise: 10% increase in risk
run: dose associated with that risk increase<\/p>\n\n\n\n
interpretation of CSF
if CSF = 1.5 x 10^-3<\/p>\n\n\n\n
if I have exposure to chemical at 1mg\/kg\/day ADD for a lifetime, my risk of cancer increases by 0.001 from background risk<\/p>\n\n\n\n
acute toxicity and exposure pattern\/level
adverse effects that occur within a short period after exposure to a toxicant<\/p>\n\n\n\n
rapid effects, usually after one dose, including death, CNS effects, irritation<\/p>\n\n\n\n
\n\nvery high on dose\/effect relationship<\/p>\n<\/blockquote>\n<\/blockquote>\n\n\n\n
chronic toxicity and exposure pattern\/level
adverse effects that occur some time after exposure to a toxicant or after extended exposure to the toxicant<\/p>\n\n\n\nresult of prolonged exposure, usually lower dose than acute, can lead to organ damage, cancer\u2026<\/p>\n\n\n\n
local toxicity vs systemic toxicity
local: toxic effect occurs at site of exposure
systemic: requires absorption of toxicant into body, then distribution (usually via bloodstream) to organs where toxic effect occurs<\/p>\n\n\n\ncharacterizing toxicity
TIME: acute vs. chronic
LOCATION: local vs. systemic<\/p>\n\n\n\nADME
absorption, distribution, metabolism, excretion<\/p>\n\n\n\n3 ways to cross a membrane
passive diffusion
facilitated diffusion
active transport<\/p>\n\n\n\npassive diffusion + examples
the movement of drugs from an area of higher concentration to lower concentration; no energy needed; follows [gradient]<\/p>\n\n\n\n3 key determinants: size, hydrophobicity, ionization\/charge<\/p>\n\n\n\n
examples: lipids, many drugs, ethanol, benzene<\/p>\n\n\n\n
hydrophobicity
the tendency to repel water; substances that are hydrophobic are nonpolar<\/p>\n\n\n\nnonpolar amino acids avoid water<\/p>\n\n\n\n
no charge + don’t dissolve in water<\/p>\n\n\n\n
facilitated diffusion + examples
molecules pass across the membrane through proteins channels; direction determined by [gradient]<\/p>\n\n\n\nexamples: fructose, glucose, sodium, potassium<\/p>\n\n\n\n
active transport + examples
the movement of materials through a cell membrane using energy; usually against [gradient]<\/p>\n\n\n\nexamples: amino acids, methyl mercury<\/p>\n\n\n\n
solubility and tox
different pollutants have different levels of solubility in polar and non-polar materials, so info about a pollutant’s relative solubility in polar\/non-polar media can help understand distribution in body<\/p>\n\n\n\nlike dissolves like<\/p>\n\n\n\n
distribution (ADME) + 3 things that influence it
is the process by which the drug becomes available to body fluids and tissues.<\/p>\n\n\n\ndirectly influenced by:<\/p>\n\n\n\n
blood flow<\/p>\n\n\n\n
drug affinity to tissue<\/p>\n\n\n\n
protein binding effect.<\/p>\n\n\n\n
metabolism (ADME)
enzymatic alteration of the chemical structure of a molecule, usually to make them easier to excrete<\/p>\n\n\n\ntwo primary systems for elimination
phase I reactions and phase II reactions<\/p>\n\n\n\nPhase I reactions + result
oxidation, reduction, or hydrolysis of drug<\/p>\n\n\n\n\n
- add polar groups<\/li>\n\n\n\n
- overlapping specificity of Phase I enzymes<\/li>\n<\/ul>\n\n\n\n
result: converts to more polar molecule and is more reactive<\/p>\n\n\n\n
Phase II reactions + results
conjugation reactions make molecules bigger by adding on other large molecules<\/p>\n\n\n\n\n
- increase water solubility >>> increase biliary or urinary excretion<\/li>\n\n\n\n
- enzymes inducible<\/li>\n<\/ul>\n\n\n\n
reactions that increase water solubility by conjugation of the drug molecule<\/p>\n\n\n\n
4 reasons we care about metabolism in tox<\/p>\n\n\n\n
\n
- it changes amount of chemical present in body<\/li>\n\n\n\n
- influences rate of excretion<\/li>\n\n\n\n
- can make a molecule more or less toxic<\/li>\n\n\n\n
- rates can vary between individuals and populations<\/li>\n<\/ol>\n\n\n\n
Excretion (ADME)
process in which drug elimination, mainly through the kidneys(urine).<\/p>\n\n\n\nother routes include bile, feces, lungs, saliva, sweat, breast milk. (Protein bound drugs cannot be filtered through the kidney once)<\/p>\n\n\n\n
Half-life of a drug
a measure of excretion; t 1\/2<\/p>\n\n\n\ntime it takes for a drug to decrease in amount by half<\/p>\n\n\n\n
body burden
amount of concentration of a toxic chemical in an individual<\/p>\n\n\n\nrisk assessment paradigm: env risk assessment steps (4)<\/p>\n\n\n\n
\n
- hazard identification<\/li>\n\n\n\n
- dose-response eval<\/li>\n\n\n\n
- exposure assessment<\/li>\n\n\n\n
- risk characterization<\/li>\n\n\n\n
- Hazard Identification
which adverse effects? at what doses?<\/li>\n\n\n\n- Dose-Response Eval
what is the relationship between amount of exposure (dose) and seriousness of adverse health effect?<\/li>\n\n\n\n- Exposure Assessment
how much, how often, and how long are humans exposed to substance in question?<\/li>\n\n\n\n- Risk Characterization
what is probability of individual or population having adverse health effect?<\/li>\n<\/ol>\n\n\n\nrisk characterization evaluates data from dose-response assessment and exposure assessment<\/p>\n\n\n\n
two primary approaches to human health risk assessment<\/p>\n\n\n\n
\n
- uncertainty factor (safety factor): assumes threshold; US EPA non-cancer endpoints<\/li>\n\n\n\n
- probabilistic modeling: assumes no threshold; US EPA carcinogens<\/li>\n<\/ol>\n\n\n\n
nonthreshold dose-response model
type of dose response curve, any dosage of a toxic chemical causes harm that increases with the dose size<\/p>\n\n\n\nnonthreshold
long latency<\/p>\n\n\n\nirreversible<\/p>\n\n\n\n
lesions become dependent of dose<\/p>\n\n\n\n
cancer = NONTHRESHOLD<\/p>\n\n\n\n
example: more exposure to benzene does not mean the cancer you may get will be worse, it just increases your chances of getting the cancer in the first place<\/p>\n\n\n\n
threshold dose response model
a threshold dosage must be reached before any detectable harmful effects occur<\/p>\n\n\n\nthreshold
often short latency<\/p>\n\n\n\noften reversible<\/p>\n\n\n\n
lesions may be dependent of dose<\/p>\n\n\n\n
severity depends on dose<\/p>\n\n\n\n
assumption for non-cancer = THRESHOLD<\/p>\n\n\n\n
2 types of exposure assessments<\/p>\n\n\n\n
\n
- measured: more precise, $$$$, source must be present<\/li>\n\n\n\n
- modeled: rely on models, require assumptions, allow better incorporation of time in exposure estimates<\/li>\n<\/ol>\n\n\n\n
exposure pathway examples
ingestion of soil, water, food, or particles; inhalation of air or particles; dermal contact with soil, sediment, water, or air<\/p>\n\n\n\nIARC Carcinogen Classification
1: carcinogenic to humans
2A: probably carcinogenic to humans
2B: possibly carcinogenic to humans
3: not classifiable
4: probably not carcinogenic<\/p>\n\n\n\nNon-cancer risk assessment<\/p>\n\n\n\n
\n
- identify available data<\/li>\n\n\n\n
- evaluate endpoints and dose-response relationships<\/li>\n\n\n\n
- choose critical effect in critical study (one sex, one species, one outcome; usually most sensitive)<\/li>\n\n\n\n
- identify POD for critical effect<\/li>\n<\/ol>\n\n\n\n
Point of Departure (POD)
non-cancer risk estimates build from POD on dose-response curve<\/p>\n\n\n\ndose-response point that marks the beginning of a low-dose extrapolation<\/p>\n\n\n\n
non-cancer risk estimates build from a \u2026..
point of departure on the dose-response curve<\/p>\n\n\n\n2 approaches to setting POD<\/p>\n\n\n\n
\n
- NOAEL<\/li>\n\n\n\n
- benchmark dose<\/li>\n<\/ol>\n\n\n\n
Benchmark Dose Approach
begins with dose at “benchmark” levels of response instead of NOAEL<\/p>\n\n\n\nuses dose-response modeling to try to estimate a place to start non-cancer risk assessment<\/p>\n\n\n\n
process: identify dose at “benchmark” response and apply appropriate uncertainty factors to benchmark dose<\/p>\n\n\n\n
LED10 – lowest effective dose causing response in 10% of animals<\/p>\n\n\n\n
ED10 – effective dose causing response in 10% of animals<\/p>\n\n\n\n
uncertainty factor approach
trying to figure out which dose is safe for humans; used to derive RfD; usually a factor of 10 as “usual uncertainty factor”<\/p>\n\n\n\ntake POD (NOAEL or BMDL10) and divide by appropriate UF<\/p>\n\n\n\n
\n\n\nusual UF = 10<\/p>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n\n\n\n
cancer-dose response
assumption that there is NO threshold<\/p>\n\n\n\nstochastic events
random events<\/p>\n\n\n\nfor all individuals, higher doses cause a higher random chance of being “hit”; random events increase with dose and risk does not go away until zero exposure<\/p>\n\n\n\n
can take a dose-response relationship in animals and predict it linearly, down to zero, to estimate cancer risk<\/p>\n\n\n\n
current EPA approach to cancer risk estimates
model data in observed range
assume low-dose linear below observed
estimate cancer slope factor (CSF) from POD<\/p>\n\n\n\ntwo methods of interpreting hazard severity<\/p>\n\n\n\n
\n
- cancer slope<\/li>\n\n\n\n
- RfDs<\/li>\n<\/ol>\n\n\n\n
RfD
Reference Dose; estimate of daily exposure to humans that is likely to be without risks during a lifetime<\/p>\n\n\n\ncompare actual dose to RfD to see if we have human toxicity. implication is that below RfD there is no appreciable risk.<\/p>\n\n\n\n
RfD= NOAEL(or LOAEL)\/(UF)(MF)<\/p>\n\n\n\n
NOAEL= No observable adverse effect level<\/p>\n\n\n\n
UF= Uncertainty Factor<\/p>\n\n\n\n
MF=Modifying Factors<\/p>\n\n\n\n
SDGs (Sustainable Development Goals)
the 2030 agenda is a set of 17 interrelated goals to end poverty, protect the planet and ensure that all people enjoy peace and prosperity.<\/p>\n\n\n\nSDG goal 6
ensure availability and sustainable mgmt of water and sanitation for all<\/p>\n\n\n\nfreshwater
does not contain any saltwater and can be rivers, lakes, streams,ponds, and wetlands<\/p>\n\n\n\ngroundwater
water that fills the cracks and spaces in underground soil and rock layers<\/p>\n\n\n\nSurface water flow
runoff stays above ground when surface is not porous or precipitation falls fast<\/p>\n\n\n\nClean Water Act (CWA)
1972; set maximum permissible amounts of water pollutants that can be discharged into waterways; aims to make surface waters swimmable and fishable<\/p>\n\n\n\nNPDES (National Pollutant Discharge Elimination System)
set water quality standards for surface waters<\/p>\n\n\n\npoint source pollution
pollution that comes from a specific site<\/p>\n\n\n\nprimarily from industrial sources and WWT plants<\/p>\n\n\n\n
CSO
Combined Sewer Overflow<\/p>\n\n\n\nwhen volume of wastewater overwhelms plant, water may be discharged directly via CSO untreated<\/p>\n\n\n\n
how are point sources regulated?
CWA requires permit from NPDES<\/p>\n\n\n\nSafe Drinking Water Act (SDWA)
1974; set maximum contaminant levels for pollutants in drinking water tha may have adverse effects on human health<\/p>\n\n\n\nNational Primary Drinking Water Regulations (NPDWR)
legally enforceable health standards for public drinking water supplies that are implemented uniformly<\/p>\n\n\n\nprimary standards<\/p>\n\n\n\n
National Secondary Drinking Water Regulations (NSCWR)
nonenforceable guidelines that include cosmetic and aesthetic effects, incl. taste<\/p>\n\n\n\nsecondary standards<\/p>\n\n\n\n
CCL
contaminant concern list
EPA required to publish
must also review at least 5 contaminants each year<\/p>\n\n\n\n3 things EPA must show to regulate:<\/p>\n\n\n\n
\n
- contaminant adversely affects human health<\/li>\n\n\n\n
- contaminant is known or substantially likely to occur in public water systems with frequency and levels of public health concern<\/li>\n\n\n\n
- regulation of contaminant presents a meaningful opportunity for health risk reduction<\/li>\n<\/ol>\n\n\n\n
MCL
Maximum Contaminate Level, legally enforceable public health goal<\/p>\n\n\n\nas close to MCLG as possible<\/p>\n\n\n\n
if no reliable method to measure containment at low enough level, EPA may set TT (treatment technique) instead of MCL — still legally enforceable!<\/p>\n\n\n\n
MCLG (Maximum Contaminant Level Goal)
level of a contaminant below which there is no known or expected health risk<\/p>\n\n\n\nwater treatment process
sedimentation, flocculation, and filtration<\/p>\n\n\n\nWater disinfection
treat water to protect against microbial pathogens at plant and in distribution system (residual)<\/p>\n\n\n\ndisinfection by-products (DBPs)
compounds formed when chlorine or other disinfectants react with naturally occurring chemicals in water<\/p>\n\n\n\n4 types of disinfectants<\/p>\n\n\n\n
\n
- chlorine — cheap, effective except cryptosporidium<\/li>\n\n\n\n
- ozone — expensive, incl. cryptosporidium<\/li>\n\n\n\n
- chlorine dioxide — generated on-site, explosive and costly, incl. cryptosporidium<\/li>\n\n\n\n
- chloramines — usually used w\/ another disinfectant, often to provide residual<\/li>\n<\/ol>\n\n\n\n
wastewater treatment
the process of removing contaminants from wastewater to make it safe enough to release into the environment<\/p>\n\n\n\nhousehold water treatment options (4)<\/p>\n\n\n\n
\n
- chlorination-Safe Water Systems (SWS)<\/li>\n\n\n\n
- combined flocculent\/ disinfectant<\/li>\n\n\n\n
- ceramic and biosand filtration<\/li>\n\n\n\n
- solar\/SODIS, boiling<\/li>\n<\/ul>\n\n\n\n
WASH
water, sanitation, hygiene<\/p>\n\n\n\nMDG (Millennium Development Goals) Goal 7
ensure environmental sustainability, incl. halving proportion of people w\/o sustainable access to drinking water and basic sanitation<\/p>\n\n\n\nimproved drinking water source
piped water, public tap, protected dug well, protected spring, rainwater<\/p>\n\n\n\nimproved sanitation
flush or pour-flush to piped sewer system, septic tank, pit latrine<\/p>\n\n\n\nhow does availability of water affect health?
significant increase in illness risk in people living far from water source<\/p>\n\n\n\nnon-point source pollution
water pollution that does not have a specific point of origin<\/p>\n\n\n\nnot regulated under NPDES<\/p>\n\n\n\n
ex: bacteria, virus<\/p>\n\n\n\n
primary nutrients of concern in NPS pollution
nitrogen and phosphorus<\/p>\n\n\n\nhelp plants grow, but if too high can lead to eutrophication (algae bloom) >> ANOXIA\/DEAD ZONE<\/p>\n\n\n\n
Biological Oxygen Demand (BOD)
tests nutrients in water<\/p>\n\n\n\n\n
- water quality indicator<\/li>\n\n\n\n
- the amount of oxygen used by microorganisms in aerobic oxidation<\/li>\n\n\n\n
- lower is better; raw sewage = 800 mg\/L; river usually below 1 mg\/L<\/li>\n\n\n\n
- can lead to hypoxia or anoxia\/dead zones<\/li>\n<\/ul>\n\n\n\n
why do marine dead zones develop?
NPS pollution<\/p>\n\n\n\nwastewater treatment stages
Primary treatment, Secondary Treatment, Tertiary (Advanced) Treatment<\/p>\n\n\n\nprimary treatment of wastewater
the removal of large particles and organic materials (up to 60% of solids) from the wastewater by using a screening process<\/p>\n\n\n\nsecondary treatment of wastewater
removes up to 90% of the oxygen-demanding wastewater, by degrading the waste aerobically using oxygen and bacteria<\/p>\n\n\n\nTertiary treatment of wastewater
removal of inorganic minerals and plant nutrients (nitrates) after primary and secondary treatment of sewage (expensive process, but increasingly necessary)<\/p>\n\n\n\nKey Waterborne Disease Agents
protozoa — can exist as cysts, resistant to disinfection; ex = giardia<\/p>\n\n\n\nbacteria — mostly from sewage; ex = typhoid, cholera, e. coli<\/p>\n\n\n\n
virus — norovirus, polio, viral hep A<\/p>\n\n\n\n
other — arsenic, nitrate, pesticides, DBPs<\/p>\n\n\n\n
fecal-oral route
feces > fluids, fingers, flies, fields, floors > food > ingested by human<\/p>\n\n\n\npreventative measures for fecal-oral transmission
sanitation, clean water supply, hygiene\/hand washing<\/p>\n\n\n\neffectiveness<\/p>\n\n\n\n
point of use water treatment: 30-50% reduction in child DD<\/p>\n\n\n\n
safe storage: 21% reduction<\/p>\n\n\n\n
hand washing with soap: 43% reduction<\/p>\n\n\n\n
sanitation: 30% or more reduction<\/p>\n\n\n\n
federal regulatory agencies responsible for food safety
USDA’s FSIS (food safety and inspection services)<\/p>\n\n\n\n\n\n\nmeat, poultry, all forms of egg<\/p>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n\n\n\n
FDA’s CFSAN (center for food safety and applied nutrition)<\/p>\n\n\n\n
\n\n\neverything else<\/p>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n\n\n\n
EPA’s OPPTS (office of prevention, pesticides, and toxic substances)<\/p>\n\n\n\n
\n\n\npesticides<\/p>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n\n\n\n
CDC’s food safety office<\/p>\n\n\n\n
\n\n\nfood borne infections<\/p>\n<\/blockquote>\n<\/blockquote>\n<\/blockquote>\n\n\n\n
role of state and local gov’t in food safety
on-the-ground inspections, esp. in restaurants and food prep sites<\/p>\n\n\n\nFood Safety Modernization Act of 2011
aims to ensure the US food supply is safe by shifting the focus from responding to contamination to preventing it<\/p>\n\n\n\nHACCP (Hazard Analysis Critical Control Point)
a systematic plan to identify and correct potential microbial hazards in the manufacturing, distribution, and commercial use of food products<\/p>\n\n\n\ntypes of violations in food safety inspection (2)
imminent health hazards — violations that are sig threat or danger to health and require immediate correction or closure (ex: no hot water, vermin)<\/p>\n\n\n\nfood borne illness risk factors — defined by CDC, ex = food from non-approved sources, inadequate cooking temps\/holding temps, etc<\/p>\n\n\n\n
salmonella
bacteria spread through indirect or direct contact with intestinal contents or excrement of animals<\/p>\n\n\n\n\n
- often associated with eggs, poultry, raw sprouts<\/li>\n\n\n\n
- bacteria destroyed by cooking to 160*F; do not grow but DO survive in fridge\/freezer<\/li>\n<\/ul>\n\n\n\n
Campylobacteriosis
caused by consuming food or water contaminated with bacteria campylobacter jejuni commonly found in GI tracts of healthy animals, esp chickens, and in untreated surface water<\/p>\n\n\n\n\n
- grows best in reduced-oxygen environment and inhibited by salt, acid and drying<\/li>\n\n\n\n
- will not multiply at temps below 85*F<\/li>\n<\/ul>\n\n\n\n
sources of Campylobacteriosis
raw\/inadequately cooked foods of animal origin
non-chlorinated water<\/p>\n\n\n\npreventative measures for Campylobacteriosis
pasteurize milk
cook raw meat
prevent cross contamination<\/p>\n\n\n\ninfection vs intoxication
Infection caused by growth of pathogen – incubation 12hrs-2wks<\/p>\n\n\n\nIntoxication caused by ingestion of toxin – symptoms appear 1-48 hrs after infection<\/p>\n\n\n\n
basic food safety practices
clean, separate, cook, chill<\/p>\n\n\n\nmunicipal solid waste (MSW)
refuse collected by municipalities from households, small businesses, and institutions<\/p>\n\n\n\nsolid waste
any discarded solid material<\/p>\n\n\n\nnon-liquid, non-soluble materials ranging from municipal garbage to sewage sludge; agricultural refuse; and mining residues<\/p>\n\n\n\n
RCRA (Resource Conservation and Recovery Act)
pollution control; treatment (recover energy and reduce hazard)<\/p>\n\n\n\n\n
- goal of this federal law is to prevent unsafe and illegal disposal of hazardous wastes on land<\/li>\n\n\n\n
- enacted in 1976 to give EPA “Cradle to Grave” authority over hazardous waste<\/li>\n<\/ul>\n\n\n\n
RCRA historical events
Times Beach — Russel Bliss sprayed waste oil onto dusty roads<\/p>\n\n\n\nCERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) 1980
pollution control; disposal (permitted and proper)<\/p>\n\n\n\n\n
- for poorly managed\/abandoned waste sites<\/li>\n\n\n\n
- gov’t or responsible party must clean up<\/li>\n\n\n\n
- very tough law<\/li>\n<\/ul>\n\n\n\n
We have an expert-written solution to this problem!
three traits of CERCLA law
retroactive — past and current owners liable<\/p>\n\n\n\nstrict — liable regardless if all laws of day were followed<\/p>\n\n\n\n
joint and several — one small waste generator can be liable for all<\/p>\n\n\n\n
CERCLA historical context
Love Canal, Niagara, NY: toxic waste dumped in 30s-50s, waste oozes decades later<\/p>\n\n\n\n“Valley of the Drums” Louisville, KY: 17,000 openly dumped drums removed<\/p>\n\n\n\n
SARA (Superfund Amendments and Reauthorization Act of 1986)<\/p>\n\n\n\n
\n
- requires emergency planning for spills and releases<\/li>\n\n\n\n
- establishes Toxic Release Inventory (TBI)<\/li>\n<\/ul>\n\n\n\n
toxic release inventory (TRI)
a program created by the Superfund Amendments and Reauthorization Act of 1984 that requires manufacturing facilities and waste handling and disposal sites to report annually on releases of more than 300 toxic materials<\/p>\n\n\n\nEPCRA
Emergency Planning and Community Right to Know Act of 1986<\/p>\n\n\n\nRCRA regulatory scope<\/p>\n\n\n\n
\n
- you have 90 days of on-site storage from when last drop is added<\/li>\n\n\n\n
- cannot “treat” HW; one drop of HW and whole thing is HW<\/li>\n\n\n\n
- generator owns waste FOREVER!<\/li>\n\n\n\n
- landfill and gas station requirements<\/li>\n<\/ul>\n\n\n\n
RCRA hazardous waste tracking<\/p>\n\n\n\n
\n
- listed or characteristic<\/li>\n\n\n\n
- manifest tracking for all RCRA waste; manifest returns to generator<\/li>\n<\/ul>\n\n\n\n
Medical waste management act
origins in RCRA<\/p>\n\n\n\nNational Priorities List (NPL)
list of contaminated sites maintained by EPA that are eligible for cleanup funds<\/p>\n\n\n\nCERCLA<\/p>\n\n\n\n
3 types of workplace hazards
chemical
physical
biological<\/p>\n\n\n\n1980 Benzene decision
SCOTUS ruled that OSHA must find that toxicant in question poses sig. health risk in workplace and that a new, lower standard is “reasonably necessary”<\/p>\n\n\n\nhow are workplace chemicals regulated?
PELs or TLVs set limits to protect workers exposed 40 hours\/week for 40 years<\/p>\n\n\n\nPEL (OSHA)
Permissible Exposure Limit<\/p>\n\n\n\n8 hour time weighted average<\/p>\n\n\n\n
STEL
Short Term Exposure Limit<\/p>\n\n\n\nOEL
Occupational Exposure Limit<\/p>\n\n\n\nTLV (ACGIH)
Threshold Limit Values<\/p>\n\n\n\n8 hour time weighted average<\/p>\n\n\n\n
IDLH
Immediately Dangerous to Life and Health<\/p>\n\n\n\nlimit to where death may occur within 30 minutes<\/p>\n\n\n\n
BEI
Biological Exposure Indices<\/p>\n\n\n\nbio-indicator of exposure
concentrations of chemical in bio fluid\/tissue<\/p>\n\n\n\nwhat do first responders’ air sampling instruments detect? (4)
combustible gas
O2 levels 19.5-30%
hydrogen sulfur (sewer gas)
carbon monoxide<\/p>\n\n\n\nwhat is a cascade impactor?
a “stack” of plates that separates particles into stages of interest to diff locations in human lungs<\/p>\n\n\n\nbigger particles deposit on earlier\/top plates and smaller make it to the bottom<\/p>\n\n\n\n
what is the 8 hour TWA limit? (ACGIH)
85 dB<\/p>\n\n\n\nhazardous range = 90-140 dB<\/p>\n\n\n\n
Confined Space Entry Standard
OSHA standard that requires space-entry restrictions, rescue procedures, and a written safe-entry program<\/p>\n\n\n\nconfined space entry standards address concerns\u2026 (3)
\u2026over adequate oxygen content in the air, toxic substance exposure, and physical exposures for workers in confined spaces<\/p>\n\n\n\nWork\/rest cycles (2)
heat stress
not legally enforceable<\/p>\n\n\n\nWBGT
Wet Bulb Globe Temperature<\/p>\n\n\n\nmeasures heat + humidity for work\/rest cycles<\/p>\n\n\n\n
clo factor
1 = naked
1.1 = t-shirt and shorts
(no correction necessary)<\/p>\n\n\n\nheavier clothing means you drop temps you can tolerate<\/p>\n\n\n\n
if wearing body armor, add _<\/em> *F to WBGT in humid climates
5<\/p>\n\n\n\nif wearing NBC clothing (MOPP 4), add _<\/em> *F to WBGT
10<\/p>\n\n\n\nACGIH
American Conference of Governmental Industrial Hygienists<\/p>\n\n\n\nprivate org
pre-dates OSHA<\/p>\n\n\n\nOSH Act of 1970
established OSHA and NIOSH<\/p>\n\n\n\neach employer shall furnish to each employee employment and a place of employment which are free from recognized hazards thht are causing or are likely to cause death or serious physical harm to employees<\/p>\n\n\n\n
NIOSH
National Institute for Occupational Safety and Health<\/p>\n\n\n\nrecommends ways to prevent workplace injury<\/p>\n\n\n\n
research<\/p>\n\n\n\n
OSHA
Occupational Safety and Health Administration<\/p>\n\n\n\nlegal authority<\/p>\n\n\n\n
hierarchy of hazard controls (5)
elimination
substitution
engineering
administrative
PPE<\/p>\n\n\n\nexamples of hierarchy of hazard controls
elimination — controlling hazard at source<\/p>\n\n\n\nsubstitution — replacing one substance or activity with a less hazardous one<\/p>\n\n\n\n
engineering — installing filters, scrubbers, guards<\/p>\n\n\n\n
administrative — procedures to reduce opportunity for exposure<\/p>\n\n\n\n
PPE — respirators, ear plugs<\/p>\n\n\n\n
STEL — when used? time period?
Short Term Exposure Limit<\/p>\n\n\n\nused when a chemical can harm within a short period of time (ex: cyanide)<\/p>\n\n\n\n
max concentration allowed during a 15min continuous period, allowed 4x\/day, 60min between<\/p>\n\n\n\n
ceiling limit
maximum concentration of a material in air that should not be exceeded, even instantaneously<\/p>\n\n\n\nair purifying respirators + examples
use filters or cartridges to remove air impurities before they can be inhaled<\/p>\n\n\n\nnever use in low O2, highly hazardous, or unknown environments<\/p>\n\n\n\n
ex: disposable mask, half mask, gas mask<\/p>\n\n\n\n
supplied air respirators + examples
pressure inside mask is positive to keep outside air from coming inside mask<\/p>\n\n\n\ncome with own air supply<\/p>\n\n\n\n
ex: SCBA, airline respirator<\/p>\n\n\n\n
conditions for mold\/mildew formation indoors
wet building materials
68-90*F<\/p>\n\n\n\n\n60% relative humidity
no air movement<\/p>\n<\/blockquote>\n\n\n\nhow to control mold\/mildew
keep humidity between 30-60%<\/p>\n\n\n\npenetrable + alpha radiation defenses
penetrable radiation: gamma, x-ray<\/p>\n\n\n\n\n
- more time<\/li>\n\n\n\n
- more distance<\/li>\n\n\n\n
- more shielding<\/li>\n<\/ul>\n\n\n\n
alpha radiation: outer covering; pose problem only if inhaled<\/p>\n\n\n\n
three industries with highest fatality rate
construction<\/p>\n\n\n\ntransportation and warehousing<\/p>\n\n\n\n
agriculture, forestry, fishing, and hunting<\/p>\n\n\n\n
high % of migrant workers<\/p>\n\n\n\n
3 control strategies for repetitive motion injuries
reduce repetition
reduce force\/weight
maintain near-neutral position<\/p>\n\n\n\nUnderstand the major function of cells
Cell differentiation: in bone marrow, adult stem cell can reproduce and splits to either myeloid or lymphoid progenitor, which can then differentiate into many kinds of cells<\/p>\n\n\n\nHomeostasis and cell injury: many adverse biological effects occur when cells are damaged, damage can be to any part of the cell, causes can be infectious agents, oxygen deprivation, trauma, chemicals, nutritional imbalances<\/p>\n\n\n\n
Apoptosis vs. Necrosis
Apoptosis- programmed cell death, active, orderly and organized; requires energy a plan and enzymatic degradation of proteins\/dna; produces neatly packed cell fragments that are recycled<\/p>\n\n\n\nNecrosis- cell damage and death, passive and disorderly; produces cell debris<\/p>\n\n\n\n
Bacteria vs Virus
bacteria
-prokaryotic cell
-most are free living
-relatively large
-antibiotics used to kill<\/p>\n\n\n\nVirus
-not a living cell (genes packaged in protein shell)
-intracellular parasite
-1\/1000 size of a bacteria
-vaccine used to prevent
-antiviral treatment<\/p>\n\n\n\nprotein synthesis
the formation of proteins by using information contained in DNA and carried by mRNA<\/p>\n\n\n\nDNA transcription RNA translation protein<\/p>\n\n\n\n
Role of DNA
storing information, copying information, and transmitting information<\/p>\n\n\n\nRole of mRNA in protein synthesis (transcription)
single stranded messenger that carries the genetic information copied from DNA in the form of a series of a three base code of words.<\/p>\n\n\n\nRole of tRNA in protein synthesis (translation)
is the key to diciphering the code words from mRNA<\/p>\n\n\n\nRole of ribosomes in protein synthesis
ribosomes are complexes made of ribosomal RNA and protein
ribosomes carry out protein synthesis in two locations<\/p>\n\n\n\na minute particle consisting of RNA and associated proteins found in large numbers in the cytoplasm of living cells. They bind messenger RNA and transfer RNA to synthesize polypeptides and proteins.<\/p>\n\n\n\n
Explain how biological and genetic factors can influence our response to environmental hazards
mutagens- pollutants in the environment that can enter the body and directly change your DNA sequence (ex. the chemicals in cigarette smoke can cause cancer)<\/p>\n\n\n\nGene-gene interactions: \u25cb occur when pollutants in the environment do not change your DNA sequence, but rather cause a chain reaction that affects the functioning of one gene that then affects the functioning of another gene
\u25a0 Ex. Regularly drinking way too much alcohol can cause the gene TACE not to produce enough of its protein. TACE protein is supposed to help the MTHFR gene make enough of its protein. Too little MTHRF protein changes the level of folate in our blood, and low folate levels may cause depression.<\/p>\n\n\n\n\u25cb Transcription factors – pollutants in the environment can indirectly affect the DNA sequence by altering transcription factors, which are responsible for starting the process of using genes to make proteins that are needed for different functions in the body
\u25a0 Ex. stress can change the amount of proteins made by genes involved in your immune system and therefore, you may get sick more easily when you’re stressed
\u25cb Epigenetics – the environment can alter your health by affecting the proteins that turns genes on or off
\u25a0 Half the genes that cause familial or inherited cancer are turned off when pollutants in the environment affect these proteins. Because they are turned off, these genes cannot suppress tumor formation or repair DNA<\/p>\n\n\n\nExplain the role of the microbiome and its role in disease prevention
Microbiota \u2192 gut microbiota<\/p>\n\n\n\n\n
- Involved in basic human biological processes<\/li>\n\n\n\n
- Chronic disease have been associated with the human microbiota
Antibiotics can disrupt microbiota<\/li>\n<\/ul>\n\n\n\nThe bacteria in the microbiome help digest our food, regulate our immune system, protect against other bacteria that cause disease, and produce vitamins including B vitamins B12, thiamine and riboflavin, and Vitamin K, which is needed for blood coagulation.<\/p>\n\n\n\n
Epigenetics
the study of environmental influences on gene expression that occur without a DNA change<\/p>\n\n\n\nDNA methylation
The addition of methyl groups to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression.<\/p>\n\n\n\nhistone modification
adding chemical modifications to proteins called histones that are involved in packaging DNA<\/p>\n\n\n\nmicro-RNA (miRNA)
A small, single-stranded RNA molecule that binds to a complementary sequence in mRNA molecules and directs associated proteins to degrade or prevent translation of the target mRNA.<\/p>\n\n\n\nMicrolesions
change in 1 bp<\/p>\n\n\n\nsubstitution<\/p>\n\n\n\n
point mutation (silent, nonsense, missense)<\/p>\n\n\n\n
frameshift mutations<\/p>\n\n\n\n
Macrolesions
chromosome aberrations<\/p>\n\n\n\n\n
- Often caused by effects on mitotic machinery, not DNA<\/li>\n\n\n\n
- Change in chromosome structure<\/li>\n\n\n\n
- Deletion, duplication, inversion, translocation\u2014may be stable<\/li>\n\n\n\n
- Acentric fragments, dicentric chromosomes\u2014usually cell death
change in chromosome number<\/li>\n\n\n\n- aneuploidy<\/li>\n\n\n\n
- polyploidy<\/li>\n<\/ul>\n\n\n\n
Why do mutations matter?
\u25cf Polymorphisms can change the function of proteins
\u25cf Many proteins (e.g., enzymes, receptors) associated with response to chemicals, drugs, and so on
\u25cf Effect may be silent, advantageous, or disadvantageous
\u25cb Example: Change in SNP can make people less drug dependent<\/p>\n\n\n\ngenotoxic carcinogens
Causes DNA replication errors, point mutations, Chromosomal abberations, also binds to DNA and is irreversible<\/p>\n\n\n\nNongenotoxic
carcinogens that modify gene expression but do not damage DNA<\/p>\n\n\n\ninduce cancer through hormonal effects, cell proliferation, increase change of replication errors, increase number of cells at risk<\/p>\n\n\n\n
mutations and cancer
Cancer-causing mutations typically occur in two categories of genes<\/p>\n\n\n\nproto-oncogenes: leading to altered forms of normal cellular genes usually involved in cell signaling and growth control<\/p>\n\n\n\n
tumor suppressor genes: whose protein products help regulate proliferation of normal cells- act as a “brake”- or promote programmed cell death (apoptosis)<\/p>\n\n\n\n
Three cancer types with highest mortality in the US<\/p>\n\n\n\n
\n
- lung\/ bronchus<\/li>\n\n\n\n
- colon\/ rectum<\/li>\n\n\n\n
- pancreas<\/li>\n<\/ol>\n\n\n\n
innate vs adaptive immunity
Innate immunity: An individual’s genetically predetermined resistance to certain diseases.<\/p>\n\n\n\nAdaptive immunity: Ability of the body to react to specific microbial infection. ANTIGEN SPECIFIC<\/p>\n\n\n\n
Antibody-Antigen Interactions
\u2022Complementary fit between antigen and antibody is needed
\u2022The better the fit the better the stimulation of the lymphocytes<\/p>\n\n\n\nCan be multiple antigens on one pathogen cell (can be proteins, sugars, etc), each recognized with a different antibody<\/p>\n\n\n\n
Vaccines
dose of a disabled or destroyed pathogen used to stimulate a long-term immune defense against the pathogen. A weakened form of the virus is given to the person so their immune system can build up immunity to the virus.<\/p>\n\n\n\nfirst pass effect
The initial metabolism in the liver of a drug absorbed from the gastrointestinal tract before the drug reaches systemic circulation through the bloodstream.<\/p>\n\n\n\nConcentration of the drug is greatly reduced before it reaches circulation<\/p>\n\n\n\n
role of liver in breaking down food, microbes, and chemical toxins
The largest gland in the body that breaks down nutrients and builds up body tissue. It acts as a storage site for minerals and vitamins. Red blood cells and Kupffer cells (cells that help eliminate harmful microorganisms as they move through the blood) are produced in the liver. Glycogen is also produced in the liver and it is regulated throughout the body. Vital when it comes to metabolic processes and disposal of toxins.<\/p>\n\n\n\nThe liver converts fat soluble toxins to water soluble substances that an be excreted.<\/p>\n\n\n\n
The enzymatic process to dispose of toxins happens in 2 phases: phase 1 (oxidation) and phase 2 (conjugation).
\u25a0 Phase 1: neutralizes toxins or changes the toxic chemical to form activated compounds that will be neutralized in stage 2. This makes toxic chemicals less harmful. Free radicals are produced (too many can damage the liver), the effects of which are reduced by antioxidants.
\u25a0 Phase 2: Conjugation pathway causes the liver cells to add another substance to the toxic chemical to make it less harmful. This makes the toxin water-soluble so it can be excreted as bile or urine.<\/p>\n\n\n\nVariability in metabolism
can affect the activity of drugs<\/p>\n\n\n\ndose-response relationship
Relationship between an administered dose and the effect on an organism<\/p>\n\n\n\nmajority of response are at mean<\/p>\n\n\n\n
\n
- Knowledge of the dose-response relationship establishes:
o Causality \u2014 that the chemical has induced the observed effects
o The threshold effect \u2014 the lowest dose where an induced effect occurs.
o The slope for the dose response \u2014 the rate at which injury builds up.
o Within a population, the majority of responses to a toxicant are similar; however, there are differences in how responses may be encountered – some individuals are susceptible and others resistant. As demonstrated in Animation 1, a graph of the individual responses can be depicted as a bell-shaped standard distribution curve. There is a wide variance in responses as demonstrated by the mild reaction in resistant individuals, the typical response in the majority of individuals, and the severe reaction in sensitive individuals.<\/li>\n<\/ul>\n\n\n\n\u25cb The variation can be due to genres, nutrition, health status, etc.
\u25cf Measures proportion of the population responding at each dose level or level of response at each dose level in controlled settings<\/p>\n\n\n\nIndividual vs. population dose relationship
Individual dose response relationship: change in severity of adverse effect with dose (also called dose-effect relationship)
\u25cb Example: Aspirin therapeutic in low dose and super bad in high doses (dose makes the poison)\u2026BUT different ppl are more sensitive to aspirin (or other chemicals) that make the dosage effects vary<\/p>\n\n\n\nPopulation dose response relationship: change in the proportion of the population responding with dose
\u25cb Different relationships for different effects
\u25cb Shape of curve gives information about population variability and toxicity of the compound<\/p>\n\n\n\npros and cons of toxicology and epi in determining toxicity
\u25cb Epidemiology:
\u25a0 Study of disease rates in human populations with and without exposure to chemical under study
\u25a0 Can discover a statistical association between exposure and disease
\u25a0 Rarely can establish causal relationship or mechanism of disease causation<\/p>\n\n\n\n\u25cb Strengths
\u25a0 Study species of interest
\u25a0 Free ranging subjects in their natural environment<\/p>\n\n\n\n\u25cb Limitations
\u25a0 Nonexperimental
\u25a0 Often qualitative
\u25a0 Usually retrospective
\u25a0 Often high-dose occupational studies
\u25cf Environmental exposures are usually much lower
\u25cf May miss diseases of women, the young, or the elderly (if we focus only on the workforce of interest)
\u25a0 Subject to confounding and bias<\/p>\n\n\n\nNOAEL and LOAEL
No Observed Adverse Effect Level: Highest dose at which there was not an observed toxic or adverse effect.<\/p>\n\n\n\nLowest Observed Adverse Effect Level: Lowest dose at which there was an observed toxic or adverse effect.<\/p>\n\n\n\n
LD50
the amount of a chemical that kills 50% of the animals in a test population<\/p>\n\n\n\nshows how lethal a dose is<\/p>\n\n\n\n
RfD
Reference Dose: Estimated daily dose that is likely to have no appreciable adverse effects during a lifetime exposure<\/p>\n\n\n\nAn estimate (with uncertainty spanning perhaps an order of magnitude) of a daily oral or dermal exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime.<\/p>\n\n\n\n
slope factor
Value, in inverse concentration or dose units, derived from the slope of a dose-response curve; in practice, limited to carcinogenic effects with the curve assumed to be linear at low concentrations or doses. The product of the slope factor and the exposure is taken to reflect the probability of producing the related effect.<\/p>\n\n\n\nmechanistic studies
\u25a0 In Vivo = ADME studies & effects of different dosing levels, durations, or patterns
\u25a0 In Vitro = Mutagenic potential, molecular mechanism of actions
\u25a0 Strengths:
\u25cf Compound-specific information
\u25cf Understanding biology should improves
\u25cb Cross-species extrapolation
\u25cb High-dose to low-dose extrapolation
\u25a0 Weakness
\u25cf Difficult to rule out alternative theories
\u25cf Often lack of necessary data for humans
\u25cf Scientific disagreement\/uncertainty<\/p>\n\n\n\nacute toxicity
adverse effects that occur within a short period after exposure to a toxicant<\/p>\n\n\n\nchronic toxicity
adverse effects that occur some time after exposure to a toxicant or after extended exposure to the toxicant<\/p>\n\n\n\nDefine absorption
movement of digested food molecules through the wall of the intestine into the blood<\/p>\n\n\n\nDefine distribution
How the drug is transported by the blood to the site of action. It requires adequate cardiac output and tissue perfusion<\/p>\n\n\n\nDefine metabolism
The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism.<\/p>\n\n\n\nDefine excretion
Removal from organisms of toxic materials, the waste product of metabolism and substances in excess requirement<\/p>\n\n\n\npassive diffusion
movement of substances across a semipermeable membrane with the concentration gradient; this process does not require energy<\/p>\n\n\n\nhydrophobicity molecules can readily cross<\/p>\n\n\n\n
facilitated diffusion
Movement of specific molecules across cell membranes through protein channels<\/p>\n\n\n\nactive transport
Energy-requiring process that moves material across a cell membrane against a concentration difference<\/p>\n\n\n\nPrimary routes of exposure
\u25cb Oral: Leads to first exposure with organ absorption
\u25cb Inhalation: air ways
\u25cb Dermal: skin contact<\/p>\n\n\n\nFour steps of environmental risk assessment<\/p>\n\n\n\n
\n
- hazard identification<\/li>\n\n\n\n
- Dose-response evaluation<\/li>\n\n\n\n
- Exposure assessment<\/li>\n\n\n\n
- Risk characterization<\/li>\n<\/ol>\n\n\n\n
hazard identification
examines the evidence that associates exposure to an agent with its toxicity and produces a qualitative judgment about the strength of that evidence<\/p>\n\n\n\nDose-response evaluation
*an attempt to quantitatively determine the relationship between exposure to a toxicant and disease.<\/p>\n\n\n\nexposure assessment
the procedure that identifies populations exposed to the toxicant, describes their composition and size, and examines the roots, magnitudes, frequencies, and durations of such exposures<\/p>\n\n\n\nrisk characterization
develops estimates of the number of excess unwarranted health events expected at different time intervals at each level of exposure<\/p>\n\n\n\nSDGs (Sustainable Development Goals)
the 2030 agenda is a set of 17 interrelated goals to end poverty, protect the planet and ensure that all people enjoy peace and prosperity.<\/p>\n\n\n\nworld met MDG for improved drinking water, but not for sanitation<\/p>\n\n\n\n
ground water quality
usually free of contaminants because the soil filters it and often available where needed at little cost<\/p>\n\n\n\nlimited volume, essentially irreplaceable once depleted<\/p>\n\n\n\n
wellhead protection areas protects groundwater by keeping any activity that can contaminate the groundwater out of the area where the aquafor is being accessed<\/p>\n\n\n\n
surface water quality
surface water requires extensive treatment before use, and drinking water often competes with other uses of surface water such as irrigation, industrial use, fisheries, and habitat<\/p>\n\n\n\nClean water act
(CWA, 1972) set maximum permissible amounts of water pollutants that can be discharged into waterways; aims to make surface waters swimmable and fishable<\/p>\n\n\n\nNPDES
Was created by the CWA. Sets water quality standards for surface water by governing what you can put in. It is against the law to discharge a pollutant from a point source without a permit.<\/p>\n\n\n\nStill require a permit to dump in navigable waterways, streams and intrastate lakes, coastal waterway, freshwater wetlands.<\/p>\n\n\n\n
1987 amendment: attention to stormwater runoff “non-point” sources<\/p>\n\n\n\n
Safe Water Drinking Act (1974)
set maximum contaminant levels for pollutants in drinking water that may have adverse effects on human health<\/p>\n\n\n\nrequires the EPA to publish a list of unregulated contaminants of concern list (CCL)<\/p>\n\n\n\n
Contaminants of concern
Specific contaminants that are of concern for human health for the exposure pathway<\/p>\n\n\n\nEPA must show:<\/p>\n\n\n\n
\n
- That the contaminant adversely affects human health<\/li>\n\n\n\n
- that it is known or substantially likely to occur in public water systems with a frequency and at levels of public health concern<\/li>\n\n\n\n
- that regulation of the contaminant presents a meaningful opportunity for health risk reduction<\/li>\n<\/ol>\n\n\n\n
MCLGs
Maximum Contaminant Level Goals (nonenforceable): a nonenforceable publish health goal<\/p>\n\n\n\n\n
- After reviewing health effects studies, the EPA sets a Maximum Contaminant Level Goal (MCLG)\u2014a nonenforceable public health goal.<\/li>\n\n\n\n
- At level where no adverse effect expected<\/li>\n\n\n\n
- Drinking water consumption compared with an oral reference dose (RfD) and other potential sources of exposure to contaminant<\/li>\n\n\n\n
- MCLG for suspect carcinogens set at zero<\/li>\n\n\n\n
- Does not consider ability to measure or treatment technology<\/li>\n\n\n\n
- Once the MCLG is established, the EPA sets an enforceable standard called a Maximum Contaminant Level (MCL).<\/li>\n\n\n\n
- Based on technical feasibility and cost<\/li>\n\n\n\n
- Set as close to the MCLG as possible<\/li>\n\n\n\n
- If there is no reliable method to measure contaminant at a low enough level, the EPA may set a treatment technique (TT) instead of an MCL\u2014still enforceable.<\/li>\n\n\n\n
- Technology or procedure (performance standard) that must be followed<\/li>\n\n\n\n
- Example is the lead and copper rules that monitor tap water and compare it with an action level, rather than an MCL<\/li>\n<\/ul>\n\n\n\n
MCLs
Maximum contaminant levels (enforceable): maximum amount of any water pollutant that might adversely affect human health<\/p>\n\n\n\nprimary vs secondary drinking water standards
NPDWR: primary are legally enforceable standards (MCLs and treatment techniques)<\/p>\n\n\n\nNSDWR: unenforceable guidelines (cosmetic effects and aesthetic effects)<\/p>\n\n\n\n
explain typical water treatment processes in developed countries including disinfection by-products<\/p>\n\n\n\n
\n
- Screen, usually surface water only<\/li>\n\n\n\n
- Flocculation \/ coagulation: chemicals that are used to clump fine particles together. Particles stick and grow big enough and eventually settle out.<\/li>\n\n\n\n
- Sedimentation: all the particles stuck to flock are removed through gravity<\/li>\n\n\n\n
- filtration: activated charcoal takes chemicals and other things out of water by binding to them<\/li>\n\n\n\n
- disinfection<\/li>\n\n\n\n
- storage<\/li>\n\n\n\n
- Distribution of water<\/li>\n<\/ol>\n\n\n\n
Disinfection
Chlorine: cheap effective, produces a number of by-products<\/p>\n\n\n\nOzone: expensive, no residual<\/p>\n\n\n\n
Chlorine dioxide: no residual<\/p>\n\n\n\n
Explain water availability and treatment challenges in developing countries
\u25cb Arsenic in drinking water, need to dig deeper wells; filtration techniques; mark high arsenic wells
\u25a0 Bangladesh example of attempts to reduce surface waterborne disease\u2026dug tube wells\u2026lead to massive arsenic exposure in the population (Persons w\/poor nutrition esp sensitive to arsenic effects)
\u25a0 2\/3rds of wells have high arsenic levels
\u25cb Water collection –> a good source if don’t live closer to drinking water. It influences hygiene practices. Less likely to practice hygiene the farther an individual is away.
\u25cb Water availability –> proportion of population using an improved drinking water has improved but disparities exist especially between rural and urban.
\u25cb Treatment challenges : Done at household level.
\u25a0 Chlorination – appropriate for use in areas where drinking water is taken from muddy ponds or rivers.
\u25a0 Ceramic and Biosand Filters – unknown effectiveness against viruses, lack of residual protection that can lead to recontamination, the need for user education to keep the filter and receptacle clean, and potential slow flow rates.
\u25a0 SODIS- the need for pretreatment of turbid water, limited volume of water that can be treated at once, length of time required to treat water, and the supply of plastic bottles required.
\u25a0 Boiling- potential for recontamination after boiling and prior to consumption is high. Water must be consumed in 24 hours.<\/p>\n\n\n\npoint source vs. non-point source pollution
Point source pollution is when contaminants enter a water supply from a single identified source<\/p>\n\n\n\nnon-point source pollution is when contaminants cannot not be traced to a source (example: animal manure\/ stormwater)<\/p>\n\n\n\n
Biological Oxygen Demand (BOD)
The amount of oxygen needed by microorganisms to decompose biological wastes into carbon dioxide, water, and minerals.<\/p>\n\n\n\nHigher BOD is associated with lower water quality because the nutrients present provide the ingredients for eutrophication and lowering of oxygen levels in a body of water. If oxygen levels get too low the water body can become hypoxic or even anoxic.<\/p>\n\n\n\n
apply systems thinking to explain why marine “dead zones” develop
\u25cb Hypoxia – Low Oxygen.
\u25cb Anoxia- no oxygen.
\u25cb Dead zones–> places where low oxygen is present. Occurs due to waste water treatment, runoffs from agriculture that results in high nutrients ( nitrogen and Phosphorous) in the water–> causes eutrophication—> bacteria breaks down algae and due to abundance of algae increases metabolization–> depletes the oxygen in the water.<\/p>\n\n\n\nExplain the function of each stage of a wastewater treatment facility.
Coming out of your house\u2014>connected to a larger sewer system & wastewater treatment facility.<\/p>\n\n\n\n\n
- Primary: First step is to run it through coarse screens- capturing grit. Grits goes to landfill by truck<\/li>\n\n\n\n
- Primary sedimentation (aka Sedimentary tanks) – gravity + time works to separate larger products –> get sewage sludge out of it and liquid is passed on to the next stage<\/li>\n\n\n\n
- Secondary (aeration tanks): Bacteria are breaking down products- (aerobic bacteria) as a result compressed air is used. some of the sludge is also returned..hence SECONDARY TREATMENT<\/li>\n\n\n\n
- Final settling Tank\u2014>sludge again is collected and then get treated water.<\/li>\n\n\n\n
- Sometimes can go to tertiary treatment where the water is disinfected. Tertiary treatment may be used to remove nutrients or reclaim water<\/li>\n\n\n\n
- Sludge Disposal (8 million tons of sludge a yr) — 60% is used in fertilizer and soil amendments Landfill Incineration Ocean dumping\u2014now banned in the United States<\/li>\n\n\n\n
- Treated waste water: Discharged to receiving body (river, lake, etc.) back into environment Used for irrigation Farm land, municipal parks, golf courses, and so on Advantages Return nutrients to soil Cheap irrigation Recharge groundwater Concerns: bacteria, metals, and so on<\/li>\n<\/ol>\n\n\n\n
Explain the challenges of wastewater management in developing countries.
Challenges arise due to lack of infrastructure, and sanitation. The size of many countries and significant rural populations makes it difficult to implement a sewer system. In regards to sanitation, there needs to be intervention at community level (changing behavior), access to sanitation facilities not just in households, and resources such as money.<\/p>\n\n\n\nDescribe the types of interventions to address water, sanitation and hygiene (WASH) as it relates to the global burden of disease.
Water- drinkable water
\u25a0 Intervention: piped water into dwelling, yard, or plot, public tap or standpipe, protected dug well (groundwater), rainwater collection, protected spring water.<\/p>\n\n\n\nSanitation refers to getting rid\/maintaining human waste.
\u25a0 Intervention: composting toilet, pit latrine with slab, ventilated improved pit (VIP) latrine, Flush or pour-flush to: –> piped sewer system, septic tank, pit latrine.<\/p>\n\n\n\nHygiene – thorough handwashing before eating and after using the toilet
\u25a0 Intervention: Need Access to community water systems, Sanitation facilities, household-level and materials and technologies
\u25a0 Intervention: changes in behavior practices—> social marketing, school programs, community participation and mobilization.
\u25a0 Intervention: enabling environments—> Policy improvements, community organizations, Institutional strengthening, Financing and cost recovery, Public-private partnerships.
\u25a0 All interventions must occur to improve hygiene.<\/p>\n\n\n\nIt reduces Diarrhea among children as well as contamination of food and water. Diarrheal episode per child per year is highest among children who are 6-11 months.<\/p>\n\n\n\n
Explain the fecal-oral route of disease transmission and preventative measures.
Feces can spread through fluids, fingers, files, and Fields\/ Floors which can contaminate the food or directly sicken the child.
Sanitation can block fecal oral route. Transmission from fluid can be blocked via clean water supply. Transmission via Fingers, Files, Field\/floors, and from food to a child can be blocked hygiene\/ handwashing.<\/p>\n\n\n\nExplain the role of the various regulatory agencies responsible for food safety
o USDA’s Food Safety and Inspection Service (FSIS): meat, poultry; eggs
o FDA’s Center for Food Safety and Applied Nutrition (CFSAN): covers everything else
o EPA’s Office of Prevention, Pesticides and Toxic Substances (OPPTS): pesticides
o CDC’s Food Safety Office: foodborne infections<\/p>\n\n\n\nHACCP (Hazard Analysis and Critical Control Points)
\u25a0 Systematic approach to food safety through prevention, rather than inspection offinal product
\u25a0 Origins in systems analysis and NASA\u2014now used worldwide for food safety
\u25a0 Map production process and identify “critical control points”
\u25a0 Thorough record keeping critical to verification and continuous improvement
\u25a0 FDA HACCP Guidance<\/p>\n\n\n\nLocal Government Role in Food Safety
\u25a0 Inspections of food-producing establishments by local health departments is a key public health measure.
\u25a0 For example, the Washington, DC, Health Regulation and Licensing Administration includes the Food Safety and Hygiene Inspection Services Division.
\u25cf Responsible for inspection of the city’s 4,700 food establishments, including boarding homes, dairies, delicatessens, bakeries, candy manufacturers, grocery stores, retail markets, ice cream manufacturers, restaurants, wholesale markets, mobile vendors, and hotels
\u25cf The staff for the program includes 17 sanitarians, two supervisors, a program manager, and a food technologist<\/p>\n\n\n\nDC Health Regulation and Licensing Administration
\u25a0 Inspect for proper handling and preparation and other food safety practices as well as potential health hazards
\u25a0 Violations can be corrected on site (COS) or within a specified period\u2014inspected again to confirm
\u25a0 Understanding DC Food Safety Reports<\/p>\n\n\n\nSalmonella source
Raw and undercooked eggs, poultry, meat, fish; unpasteurized milk.<\/p>\n\n\n\noften associated with eggs or any egg-based food, salads (such as tuna, chicken or potato), poultry, beef, pork, processed meats, meat pies, fish, cream desserts and fillings, sandwich fillings, raw sprouts, and milk products.<\/p>\n\n\n\n
Salmonella health effect
The bacteria are spread through indirect or direct contact with the intestinal contents or excrement of animals, including humans.<\/p>\n\n\n\nSalmonella protective measures
bacteria grow at temperatures between 41-113F. They are readily destroyed by cooking to 160F and do not grow (but do survive) at refrigerator or freezer temperatures.<\/p>\n\n\n\nCampylobacteriosis source
\u25a0 caused by consuming food or water contaminated with the bacteria Campylobacter jejuni, which is commonly found in the intestinal tracts of healthy animals (especially chickens) and in untreated surface water.
\u25a0 Raw and inadequately cooked foods of animal origin and non-chlorinated water are the most common sources of human infection (e.g., raw milk, undercooked chicken, raw hamburger, raw shellfish).<\/p>\n\n\n\nCampylobacteriosis symptoms
Fever, headache, myalgia –> severe abdominal pain –> bloody\/watery diarrhea
3-7 day duration<\/p>\n\n\n\nCampylobacteriosis protective measures
\u25a0 The organism grows best in a reduced-oxygen environment; is easily killed by heat (120F); is inhibited by acid, salt, and drying; and will not multiply at temperatures below 85F.
\u25a0 Preventive measures for Campylobacter infections include pasteurizing milk; avoiding post-pasteurization contamination; cooking raw meat, poultry, and fish; and preventing cross-contamination between raw and cooked or ready-to-eat foods.<\/p>\n\n\n\ninfection vs intoxication
infection is microbes grown in GI tract and can become a systemic infection often causing fever<\/p>\n\n\n\nintoxication is microbes located in food that produce toxins and have rapid onset<\/p>\n\n\n\n
\u25cb Infection vs. intoxication
\u25a0 Salmonella, Campylobacter, E. coli, and Listeria bacteria in food cause food infection.
\u25a0 Staphylococcus and Clostridium botulinum bacteria produce a toxin (or poison) as a by-product of growth and multiplication in food and cause food intoxication.
\u25cb Salmonella and Campylobacter are two of the most common sources of human foodborne disease found in CDC FoodNet program<\/p>\n\n\n\n\u25cf Explain issues\/conditions that challenge food safety and some basic food safety practices
\u25cb Types of Violation in Food Safety Inspection
\u25a0 Imminent health hazards: violations that are a significant threat or danger to health; these violations require immediate correction or immediate closure of the establishment and can range from operating without hot water, severe temperature abuse of food, or severe vermin infestation, to the failure of a certified food manager to be on duty during hours of operation
\u25a0 Foodborne illness risk factors: defined by CDC and include food from non-approved sources, inadequate cooking temperatures, improper holding temperatures, cross-contamination, and poor personal hygiene
\u25a0 Good retail practices: systems to control basic operational and sanitation condition within a food establishment; some examples are pest control, equipment maintenance, plumbing, water, andphysical facilities
\u25cb Learning About Local Practices
\u25a0 In Virginia, all restaurant inspections, including specific citations and reactions, posted online: Virginia Department of Health’s Inspection Database
\u25a0 DC has searchable database of food inspections: Health Regulation and Licensing Administration
\u25a0 Montgomery County, Maryland: Data Montgomery – Food Inspection<\/p>\n\n\n\nsolid waste
any discarded material from industrial, commercial, govt, mining and agriculture; including solid, semi-solid, liquid, or contained gaseous material<\/p>\n\n\n\nhazardous waste
Any material that can be harmful to human health or the environment if it is not properly disposed of<\/p>\n\n\n\nTwo types:<\/p>\n\n\n\n
\u25cb listed or characteristic
\u25a0 Listed
\u25cf Non-specified sources -> toluene, MEK, etc
\u25cf Specific sources -> sludge from steel making plant
\u25a0 Characteristic – toxicity, ignitable, reactive, corrosive<\/p>\n\n\n\nMunicipal solid waste
the waste materials produced in homes, businesses, schools, and other places in a community<\/p>\n\n\n\n\u25a0 EPA does not manage at household level, but regulates landfills, etc<\/p>\n\n\n\n
Resource Conservation and Recovery Act (RCRA, 1976) History
Times Beach, MO
\u25cf Russel Bliss (farmer who was trying to tame the dust on his roads) sprayed waste oil from Pharma Company on ~23 miles of road in his town, Times Beach
\u25cf Waste oil contained dioxin, which is a toxin
\u25cf EPA realized this and declared a health emergency
\u25cf RCRA law passed in 1976
\u25cf 1982 flood hits Times Beach \u2192 CDC recommends to not re-inhabit
\u25cf Town is de-incorporated after incinerator burns 250,000 tons of soil in 1995<\/p>\n\n\n\nResource Conservation and Recovery Act (RCRA, 1976) Scope
\u25cf Defined waste as a technical term (see definitions above)
\u25cf Main Intention of RCRA: to disincentivize companies from trying to handle their own hazardous waste; how do we prevent accumulation of hazardous waste?
\u25cb If you’re doing something that releases hazardous waste, by law, you’re not allowed to collect\/neutralize it on your own – you MUST send it to an EPA certified waste center so that they can do it
\u25cf Exclusions: domestic waste, fossil fuels, mining wastes, oil and gas refining waste, hydrofracking
\u25cf Subtitles A-J of the law classify various kinds of RCRA waste:
\u25cb Subtitle C: Hazardous Waste “Cradle to Grave Tracking”
\u25a0 “Cradle to Grave” – making sure the hazardous waste from an industrial company actually gets dropped off at an EPA facility
\u25a0 Ex – following a truck that is carrying the waste from the factory to the facility to make sure the waste is properly disposed of
\u25cb Subtitle D: Non-Hazardous Wastes (Municipal Landfills, etc)
\u25cb Subtitle F: Fed Responsibilities (waived sovereign immunity)
\u25cb Subtitle I: Underground Storage Tanks
\u25cb Subtitle J: Medical Waste (now under Medical Waste Management Act)
\u25cf Other Important Details
\u25cb RCRA waste is way more expensive to dispose of than regular municipal waste
\u25cb Mixtures – if one drop of Hazardous waste in barrel, it’s all hazardous waste
\u25cb Cannot store waste for more than 90 days on site
\u25cb You cannot “treat” hazardous waste
Every container MUST be properly labeled for disposal with detail on the contents<\/p>\n\n\n\nComprehensive Environmental Response Compensation and Liability Act (CERCLA) History
\u25cf Love Canal, City of Niagara, NY
\u25cb 1930s-1950s – Hooker Chemicals dumps ~21,000 tons of Toxic waste into land
\u25cb 1953 – City of Niagara buys land from Hooker Chemical for $1 (despite the company disclosing that there are tons of chemicals in that land and advising against the purchase); deed restriction (i.e. deed mentioned that the land was hazardous and restricted homes\/schools from being built there)
\u25cb 1960s – homes and schools were built near site
\u25cb 1978 – waste found oozing from the ground
\u25cb President Carter declares Federal Health Emergency
\u25cb 1980 – CERCLA Law Passed
\u25cf “Valley of the Drums” near Louisville, KY
\u25cb Publicized Love Canal was suburban neighborhood; valley of the drums was more visual
\u25cb 17,000 openly dumped drums were removed from 13 acres
\u25cb 1966 – several barrels burned for weeks – still ignored
\u25cb 1979 – EPA issues Emergency cleanup
\u25cb 1980 – CERCLA Law Passed<\/p>\n\n\n\nWe have an expert-written solution to this problem!
CERCLA Scope
\u25cf Details of Law
\u25cb National Priorities List (NPL) – hazardous waste sites based on health hazard ranking system
\u25cb Government responsible parties MUST cleanup
\u25cb Very Tough Law – Polluter Pays
\u25a0 Retroactive – all past and current owners liable
\u25a0 Strict – liable regardless if all laws of the day were followed
\u25a0 Joint and several – one small waste generator can be liable for all
\u25cb Main idea of CERCLA Law: “If you harm the environment and then the environment harms people, YOU will be held responsible for that”; how can we control\/manage the hazardous waste that exists and holding entities accountable for it; how do we clean this up
\u25cf When a company no longer exists to be held responsible for its waste, EPA pays (so that means the taxpayers) \u2192 budget is ~$250 mil\/year, but we need a LOT more to actticually make progress<\/p>\n\n\n\nSuperfund Amendment Reauthorization Act (SARA) History
\u25cf Bhopal, India – 1984
\u25cb Former DOW chemicals had a Carbide Pesticide plant in India
\u25cb “Worst Industrial Accident” in history – at midnight, 42 tons of Methyl Isocyanate (MIC) reacts with water, over pressurized tank, released into the air
\u25cb Thousands of people wake up with burning sensation in eyes, lungs, etc.
\u25cb Death toll under dispute – anywhere from 4,000-25,000
\u25cb 10,000+ with long term effects
\u25cf Outrage over Bhopal lead to SARA<\/p>\n\n\n\nSuperfund Amendment Reauthorization Act (SARA) Scope
\u25cf Details of Law
\u25cb Created Emergency Planning and Community “Right to Know Act” (EPCRA) – citizens have a right to know about chemicals in the community
\u25cb Requires emergency spill and release response
\u25cb Established the Toxic Release Inventory (TRI)
\u25a0 Must report all chemical releases, storage, usage, disposal, (above certain reportable thresholds)
\u25a0 Publically available – powerful incentive to reduce emissions<\/p>\n\n\n\nDescribe the health impacts for the globalization of waste management (e.g. recycling overseas etc)
\u25cb globalization of waste has detrimental health impacts on the population that lives there – poorly managed – often burned or thrown into a landfill – causes SEVERE pollution
\u25cb These landfills abroad also can sometimes overflow into the surrounding bodies of water with enough rain\/floods leading to water pollution
\u25cb All of this pollution leads to large negative health impacts on citizens
\u25cf Other Helpful Graphics\/slides for this Lecture<\/p>\n\n\n\nAmerican Conference of Governmental Industrial Hygienists (ACGIHA)
American Conference of Governmental Industrial Hygienists
private organization, existed long before OSHA. They can do whatever without being sued.<\/p>\n\n\n\nOSHA (Occupational Safety and Health Administration)
\u25a0 To assure so far as possible every working man and woman safe and healthful working conditions \u2026 no employee will suffer diminished health, function or life expectancy from work
\u25a0 OSHA – Occupational Safety & Health Admin – legal authority – set rules
\u25a0 NIOSH – National Institute of OSH – research to help figure out standards. OSHA decides to pursue what NIOSH suggests
\u25a0 OSHA can be sued<\/p>\n\n\n\n\u25cb 1970 – OSHA adopts 1968 ACGIH Exposure Standards<\/p>\n\n\n\n
Match any control strategy into the hierarchy of hazard controls
Elimination: controlling the hazard at source<\/p>\n\n\n\nSubstitution: replacing one substance or activity with a less hazardous one<\/p>\n\n\n\n
Engineering: installing filters, scrubbers, guards<\/p>\n\n\n\n
Administrative: procedures to reduce opportunity for exposure<\/p>\n\n\n\n
Personal Protective Equipment: respirators, ear plugs<\/p>\n\n\n\n
Explain the difference between 8-hour PELs\/TLVs, STELs\/Ceiling Limits and IDLH
\u25cb We regulate workplace chemicals by setting PELs or TLVs – limit set to protect adult worker exposed 40 hours per week for 40 yrs
\u25a0 OSHA – PELs
\u25a0 ACGIH – TLVs
\u25a0 TLV: threshold limit values\u2026ACGIH limit, so scientifically sound but not legally enforceable
\u25a0 PEL: permissible exposure limit: OSHA value
\u25cf Both TLVs and PELs use either ceiling limits (max concentration allowed\u2026denoted by c next to number) or 8 hour time weighted average (used for most chemicals with long-term toxicities)
\u25a0 Most shifts are 8 hours, avg exposure is compared to standard. If below, you are OK
\u25a0 Ceiling limit: highest limit, can’t go over this limit ever!<\/p>\n\n\n\nAir Purifying Respirators vs. Supplied Air Respirators
\u25cb Respiratory Fit Test Program is critical for worker education and assuring a proper seal
\u25a0 Air Purifying Respirators – must use the nearby air (never use in low oxygen, highly hazardous or unknown environments)
\u25cf Disposable Masks Half Mask Full Facepiece Gas Mask
\u25a0 Supplied Air Respirators – comes with their own air supply
\u25cf Airline Respirator, Self Contained Breathing Apparatus (SCBA)
\u25cf Emergency Escape Only when escape will take time – good for 5-10 min
\u25cb Respirator only protects user and mask protects everyone else
\u25cb Asbestos removal requires encapsulated area, suits with respirators and constant air sampling<\/p>\n\n\n\nExplain the conditions for molds\/mildew formation indoors
Molds\/Mildews love wet building materials, 68-90F, rel humidity >60%, no air movement<\/p>\n\n\n\nWe basically control by keeping humidity between 30-60%<\/p>\n\n\n\n
Measuring ventilation is a key aspect of controlling indoor air pollution, chemicals, mold etc<\/p>\n\n\n\n
Discuss the various types of physical workplace hazards and approaches to protect workers
Hazardous Noise: NOISE – 8-hr TWA limit is 85 dBA according to ACGIH, Once nerve endings are damaged from too much noise, we lose hearing, Use ear plugs\/helmets to protect, We attach a device near the ear to measure noise levels through an 8 hour shift<\/p>\n\n\n\nConfined Space Entry, Have standby worker, alarm horn, emergency SCBA, lifeline to safety harness, gas and fume extractor, Heat Stress, Radiation Workers
\u25a0 For penetrable radiation (gamma), your only defenses are: More Time, More Distance, More Shielding
\u25a0 Outer covering is mainly for alpha particles that pose a problem only if inhaled<\/p>\n\n\n\nLasers: can even be used as weapons of mass destruction (Temperature: wet bulb global temperature (WBGT))<\/p>\n\n\n\n
All Values in WBGT (wet bulb globe temperature), which takes humidity and solar radiation into account<\/p>\n\n\n\n
Name the three industries with the highest fatality “rate”
Construction, transportation\/warehousing, agriculture\/forestry\/fishing\/hunting<\/p>\n\n\n\nErgonomics
The study of workplace equipment design or how to arrange and design devices, machines, or workspace so that people and things interact safely and most efficiently.<\/p>\n\n\n\n\u25cb Primary control methods are:
\u25a0 Reduce repetition (times\/day)
\u25a0 Reduce force\/weight
\u25a0 Position – maintain near neutral<\/p>\n\n\n\nDiscuss the ethical impacts of poor occupational health programs in developing countries
\u25cb Worldwide Worker Mortality
\u25a0 International Labour Organization (ILO) estimates 2.3 million people die from at work each year (6000\/day)
\u25a0 ILO estimates 340 million occupational accidents per year (nearly 1M\/day)
\u25a0 Record keeping is poor in many countries and there is a lot of underreporting (if it’s not measured, it will not be fixed)
\u25cb 1129 garment workers killed in 2013 from collapse of the Rana Plaza in Bangladesh
\u25a0 Garment industry pays ~$1\/hour and basically moves into poor countries
\u25a0 80% were female aged 18-20
\u25a0 Working conditions are often poor – physical \/verbal abuse, forced overtime, unsanitary conditions, denial of paid maternity leave, and failure to pay, long hours\/no breaks.<\/p>\n\n\n\nPubh 6011 final latest exam questions and answers
pubh 6011 final exam
pubh 6011 midterm<\/p>\n","protected":false},"excerpt":{"rendered":"Two types of cell deathapoptosis: programmed cell deathnecrosis: cell damage and death Virus vs bacteriavirus: only active within host cells which they need to reproducebacteria: single-celled organisms that produce own energy and can reproduce on their own DNA base pairingA-TG-C DNA strands held together by\u2026hydrogen bonds DNA to proteinDNA encodes the sequence of proteins carried […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[],"tags":[],"class_list":["post-111114","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/111114","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=111114"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/111114\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=111114"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=111114"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=111114"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}