Two types of cell death
apoptosis: programmed cell death
necrosis: cell damage and death
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
DNA base pairing
A-T
G-C
DNA strands held together by…
hydrogen bonds
DNA to protein
DNA encodes the sequence of proteins carried in DNA
Gene
DNA coding (for protein, for trait)
Protein functions
structural support, storage, transport, cellular communications, movement, and defense against foreign substances
Protein sequence
determines how protein will fold
Protein structure
determines function
Enzyme
enhances rate of chemical reaction in body; catalysts, so not used up in reaction
Process of DNA to protein
DNA > transcription > RNA > transcription > protein
Genome
all of an organism’s genetic material
Epigenetics
the study of influences on gene expression that occur without a DNA change
determines which genes are expressed
Epigenetics results in
heritable changes in the phenotype without changes to DNA sequence/structure (genotype)
Can epigenetic modifications be transferred from generation to generation?
YES
Three mechanisms of epigenetics
- DNA methylation
- histone modification
- micro-RNAs
DNA methylation
adding a methyl group to DNA to switch off the gene
possible connection between DNA methylation of 5 genes and PM 2.5
Histone
protein molecule around which DNA is tightly coiled in chromatin
Histone modification
changes in the structure of histones that make it more or less likely that a segment of DNA will be transcribed
acetyl group allows for transcription
Epigenetic factor that binds to histone tail
acetyl group; allows for transcription
Micro-RNAs
bind to complementary RNA to prevent translation
Mutation
heritable changes in genetic information
genotype change
Microlesions
base pair substitution
2 types of microlesions
change in DNA sequence
change in codon (if coding region)
Change in codon – 3 outcomes
no effect = degenerate code
missense mutation = change amino acid, sometimes function
nonsense mutation = premature termination or splice change
Types of genetic mutations in lecture
microlesions
frameshift mutations
macro lesions
Types of genetic mutations
- Deletion
- Duplication
- Inversion
- Insertion
- Translocation
frameshift mutation
mutation that shifts the “reading” frame of the genetic message by inserting or deleting a nucleotide
consequences: altered protein, often non-functional
macrolesions
chromosomal aberrations
change in chromosomal structure
change in chromosome number
Cause of chromosomal aberration
effects on mitotic machinery, not DNA
Macrolesion mutation: change in chromosome structure
deletion, duplication, inversion, translocation — usually cell death
Macrolesion mutation: change in chromosome number
aneuploidy: increase number of one+ chromosomes
polyploidy: increase in whole set
Aneuploidy
A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number.
Polyploidy
condition in which an organism has extra sets of chromosomes
polymorphism
the individual differences of form among the members of a species
can change function of proteins
Health effects of mutation
germ cells/ova: point mutations may be lethal
somatic cells: source of variability (polymorphism); concern = carcinogenesis
How does cancer arise?
DNA mutations in cells
uncontrolled proliferation
Proto-oncogene mutation
leads to altered forms of normal cellular genes
tumor supressor gene
mutation
can promote apoptosis
can act as “brake” to regulate proliferation of normal cells
Genotoxic compounds
directly alter DNA
point mutations
chromosomal aberrations
point mutation
gene mutation in which a single base pair in DNA has been changed
nongenotoxic compound
do not directly alter DNA but can increase cancer risk
increase chance of replication errors and increase number of cells at risk
cancer types with highest mortality in US
women: lung, breast, colon
men: lung, prostate, colon
innate immunity
- immunity that is present before exposure and effective from birth
- responds to a broad range of pathogens
physical barriers help prevent entry
0-12 hours after infection — immediate
adaptive immunity
- the ability to recognize and remember specific antigens and mount an attack on them
detects molecules (usually proteins) on surface of cells and learns to ignore self proteins
delayed
non-self proteins
antigens, substance that can promote immune response
what type of cell makes antibodies?
B lymphocytes
can there be multiple antigens on one pathogen?
YES
antigen
a toxin or other foreign substance that induces an immune response in the body, especially the production of antibodies
antibody
a substance produced by the body that destroys or inactivates an antigen that has entered the body
Antigen reaction
- a decrease in BP
- a release of epinephrine and norepinephrine from the adrenal medulla
- an increase in the Heart Rate and vasoconstriction occurs
- an increase in the BP
basophils and mast cells
release chemicals that mediate inflammation and allergic responses
neutrophils
ingest and destroy invaders
eosinophils
destroy invaders, especially antibody coated parasites
monocytes and macrophages
ingest and destroy invaders, antigen presentation
dendritic cells
recognize pathogen and activate other immune cells by antigen presentation
antigen-presenting cells
natural killer cells (NK cells)
pursue diseased cells
How vaccines work
- mimic natural infection, teach your immune system how to recognize a particular pathogen
- develop Memory T and B cells
goal of immunization
produce memory of vaccine antigen via large population of memory cells
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
drug goes to liver first
Role of liver in digestion
regulates metabolism of the macronutrients, stores some nutrients (glycogen), and produces bile
response to toxicant influenced by…
differences in pharmacokinetics and pharmacodynamics due to species/strain, sex, age, disease, and enzyme induction (prior exposure)
enzyme induction
the increase in hepatic enzyme activity that results in greater metabolism of drugs
2 basic functions of toxicology
- assess likelihood of adverse effects
- study the nature and mechanics of adverse effects
mechanistic study
answers “How does this system work?”
study of potential modes of action in lab animals (in vivo) or tissues, cells, etc (in vitro)
in vivo studies in tox
ADME studies
effect of different dosing levels
in vitro studies in tox
mutagenic potential
molecular mechanisms of action
strengths and weaknesses of mechanistic studies
strengths: compound-specific information, cross-species extrapolation, dose extrapolation
weaknesses: difficult to rule out alt theories; often lack data for humans
dose-effect relationship
the relationship between drug dose and blood, or other biological fluid concentrations
dose-response relationship
the relationship between the different doses and the responses they generate
how is toxicity quantified?
dose-effect and dose-response relationships
LD50
the point at which 50 percent of the test organisms die from a toxin
lethal dose in mg/kg
used to compare relative acute toxicity
LC50
concentration of a substance needed to kill 50% of the organisms within a specified period of time
lethal concentration in ppm or mass/volume
ADD
average daily dose
ADD formula
C x IR / BW = average daily dose in mg/kg/day
C= concentration
IR= intake rate
BW= body weight
NOAEL and LOAEL
No Observed Adverse Effect Level
Lowest Observed Adverse Effect Level
CSF
cancer slope factor
0.10/LED10
provides estimate of increase in cancer risk per mg/kg/day of ADD
rise and run in CSF
rise: 10% increase in risk
run: dose associated with that risk increase
interpretation of CSF
if CSF = 1.5 x 10^-3
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
acute toxicity and exposure pattern/level
adverse effects that occur within a short period after exposure to a toxicant
rapid effects, usually after one dose, including death, CNS effects, irritation
very high on dose/effect relationship
chronic toxicity and exposure pattern/level
adverse effects that occur some time after exposure to a toxicant or after extended exposure to the toxicant
result of prolonged exposure, usually lower dose than acute, can lead to organ damage, cancer…
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
characterizing toxicity
TIME: acute vs. chronic
LOCATION: local vs. systemic
ADME
absorption, distribution, metabolism, excretion
3 ways to cross a membrane
passive diffusion
facilitated diffusion
active transport
passive diffusion + examples
the movement of drugs from an area of higher concentration to lower concentration; no energy needed; follows [gradient]
3 key determinants: size, hydrophobicity, ionization/charge
examples: lipids, many drugs, ethanol, benzene
hydrophobicity
the tendency to repel water; substances that are hydrophobic are nonpolar
nonpolar amino acids avoid water
no charge + don’t dissolve in water
facilitated diffusion + examples
molecules pass across the membrane through proteins channels; direction determined by [gradient]
examples: fructose, glucose, sodium, potassium
active transport + examples
the movement of materials through a cell membrane using energy; usually against [gradient]
examples: amino acids, methyl mercury
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
like dissolves like
distribution (ADME) + 3 things that influence it
is the process by which the drug becomes available to body fluids and tissues.
directly influenced by:
blood flow
drug affinity to tissue
protein binding effect.
metabolism (ADME)
enzymatic alteration of the chemical structure of a molecule, usually to make them easier to excrete
two primary systems for elimination
phase I reactions and phase II reactions
Phase I reactions + result
oxidation, reduction, or hydrolysis of drug
- add polar groups
- overlapping specificity of Phase I enzymes
result: converts to more polar molecule and is more reactive
Phase II reactions + results
conjugation reactions make molecules bigger by adding on other large molecules
- increase water solubility >>> increase biliary or urinary excretion
- enzymes inducible
reactions that increase water solubility by conjugation of the drug molecule
4 reasons we care about metabolism in tox
- it changes amount of chemical present in body
- influences rate of excretion
- can make a molecule more or less toxic
- rates can vary between individuals and populations
Excretion (ADME)
process in which drug elimination, mainly through the kidneys(urine).
other routes include bile, feces, lungs, saliva, sweat, breast milk. (Protein bound drugs cannot be filtered through the kidney once)
Half-life of a drug
a measure of excretion; t 1/2
time it takes for a drug to decrease in amount by half
body burden
amount of concentration of a toxic chemical in an individual
risk assessment paradigm: env risk assessment steps (4)
- hazard identification
- dose-response eval
- exposure assessment
- risk characterization
- Hazard Identification
which adverse effects? at what doses? - Dose-Response Eval
what is the relationship between amount of exposure (dose) and seriousness of adverse health effect? - Exposure Assessment
how much, how often, and how long are humans exposed to substance in question? - Risk Characterization
what is probability of individual or population having adverse health effect?
risk characterization evaluates data from dose-response assessment and exposure assessment
two primary approaches to human health risk assessment
- uncertainty factor (safety factor): assumes threshold; US EPA non-cancer endpoints
- probabilistic modeling: assumes no threshold; US EPA carcinogens
nonthreshold dose-response model
type of dose response curve, any dosage of a toxic chemical causes harm that increases with the dose size
nonthreshold
long latency
irreversible
lesions become dependent of dose
cancer = NONTHRESHOLD
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
threshold dose response model
a threshold dosage must be reached before any detectable harmful effects occur
threshold
often short latency
often reversible
lesions may be dependent of dose
severity depends on dose
assumption for non-cancer = THRESHOLD
2 types of exposure assessments
- measured: more precise, $$$$, source must be present
- modeled: rely on models, require assumptions, allow better incorporation of time in exposure estimates
exposure pathway examples
ingestion of soil, water, food, or particles; inhalation of air or particles; dermal contact with soil, sediment, water, or air
IARC Carcinogen Classification
1: carcinogenic to humans
2A: probably carcinogenic to humans
2B: possibly carcinogenic to humans
3: not classifiable
4: probably not carcinogenic
Non-cancer risk assessment
- identify available data
- evaluate endpoints and dose-response relationships
- choose critical effect in critical study (one sex, one species, one outcome; usually most sensitive)
- identify POD for critical effect
Point of Departure (POD)
non-cancer risk estimates build from POD on dose-response curve
dose-response point that marks the beginning of a low-dose extrapolation
non-cancer risk estimates build from a …..
point of departure on the dose-response curve
2 approaches to setting POD
- NOAEL
- benchmark dose
Benchmark Dose Approach
begins with dose at “benchmark” levels of response instead of NOAEL
uses dose-response modeling to try to estimate a place to start non-cancer risk assessment
process: identify dose at “benchmark” response and apply appropriate uncertainty factors to benchmark dose
LED10 – lowest effective dose causing response in 10% of animals
ED10 – effective dose causing response in 10% of animals
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”
take POD (NOAEL or BMDL10) and divide by appropriate UF
usual UF = 10
cancer-dose response
assumption that there is NO threshold
stochastic events
random events
for 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
can take a dose-response relationship in animals and predict it linearly, down to zero, to estimate cancer risk
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
two methods of interpreting hazard severity
- cancer slope
- RfDs
RfD
Reference Dose; estimate of daily exposure to humans that is likely to be without risks during a lifetime
compare actual dose to RfD to see if we have human toxicity. implication is that below RfD there is no appreciable risk.
RfD= NOAEL(or LOAEL)/(UF)(MF)
NOAEL= No observable adverse effect level
UF= Uncertainty Factor
MF=Modifying Factors
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.
SDG goal 6
ensure availability and sustainable mgmt of water and sanitation for all
freshwater
does not contain any saltwater and can be rivers, lakes, streams,ponds, and wetlands
groundwater
water that fills the cracks and spaces in underground soil and rock layers
Surface water flow
runoff stays above ground when surface is not porous or precipitation falls fast
Clean 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
NPDES (National Pollutant Discharge Elimination System)
set water quality standards for surface waters
point source pollution
pollution that comes from a specific site
primarily from industrial sources and WWT plants
CSO
Combined Sewer Overflow
when volume of wastewater overwhelms plant, water may be discharged directly via CSO untreated
how are point sources regulated?
CWA requires permit from NPDES
Safe Drinking Water Act (SDWA)
1974; set maximum contaminant levels for pollutants in drinking water tha may have adverse effects on human health
National Primary Drinking Water Regulations (NPDWR)
legally enforceable health standards for public drinking water supplies that are implemented uniformly
primary standards
National Secondary Drinking Water Regulations (NSCWR)
nonenforceable guidelines that include cosmetic and aesthetic effects, incl. taste
secondary standards
CCL
contaminant concern list
EPA required to publish
must also review at least 5 contaminants each year
3 things EPA must show to regulate:
- contaminant adversely affects human health
- contaminant is known or substantially likely to occur in public water systems with frequency and levels of public health concern
- regulation of contaminant presents a meaningful opportunity for health risk reduction
MCL
Maximum Contaminate Level, legally enforceable public health goal
as close to MCLG as possible
if no reliable method to measure containment at low enough level, EPA may set TT (treatment technique) instead of MCL — still legally enforceable!
MCLG (Maximum Contaminant Level Goal)
level of a contaminant below which there is no known or expected health risk
water treatment process
sedimentation, flocculation, and filtration
Water disinfection
treat water to protect against microbial pathogens at plant and in distribution system (residual)
disinfection by-products (DBPs)
compounds formed when chlorine or other disinfectants react with naturally occurring chemicals in water
4 types of disinfectants
- chlorine — cheap, effective except cryptosporidium
- ozone — expensive, incl. cryptosporidium
- chlorine dioxide — generated on-site, explosive and costly, incl. cryptosporidium
- chloramines — usually used w/ another disinfectant, often to provide residual
wastewater treatment
the process of removing contaminants from wastewater to make it safe enough to release into the environment
household water treatment options (4)
- chlorination-Safe Water Systems (SWS)
- combined flocculent/ disinfectant
- ceramic and biosand filtration
- solar/SODIS, boiling
WASH
water, sanitation, hygiene
MDG (Millennium Development Goals) Goal 7
ensure environmental sustainability, incl. halving proportion of people w/o sustainable access to drinking water and basic sanitation
improved drinking water source
piped water, public tap, protected dug well, protected spring, rainwater
improved sanitation
flush or pour-flush to piped sewer system, septic tank, pit latrine
how does availability of water affect health?
significant increase in illness risk in people living far from water source
non-point source pollution
water pollution that does not have a specific point of origin
not regulated under NPDES
ex: bacteria, virus
primary nutrients of concern in NPS pollution
nitrogen and phosphorus
help plants grow, but if too high can lead to eutrophication (algae bloom) >> ANOXIA/DEAD ZONE
Biological Oxygen Demand (BOD)
tests nutrients in water
- water quality indicator
- the amount of oxygen used by microorganisms in aerobic oxidation
- lower is better; raw sewage = 800 mg/L; river usually below 1 mg/L
- can lead to hypoxia or anoxia/dead zones
why do marine dead zones develop?
NPS pollution
wastewater treatment stages
Primary treatment, Secondary Treatment, Tertiary (Advanced) Treatment
primary treatment of wastewater
the removal of large particles and organic materials (up to 60% of solids) from the wastewater by using a screening process
secondary treatment of wastewater
removes up to 90% of the oxygen-demanding wastewater, by degrading the waste aerobically using oxygen and bacteria
Tertiary treatment of wastewater
removal of inorganic minerals and plant nutrients (nitrates) after primary and secondary treatment of sewage (expensive process, but increasingly necessary)
Key Waterborne Disease Agents
protozoa — can exist as cysts, resistant to disinfection; ex = giardia
bacteria — mostly from sewage; ex = typhoid, cholera, e. coli
virus — norovirus, polio, viral hep A
other — arsenic, nitrate, pesticides, DBPs
fecal-oral route
feces > fluids, fingers, flies, fields, floors > food > ingested by human
preventative measures for fecal-oral transmission
sanitation, clean water supply, hygiene/hand washing
effectiveness
point of use water treatment: 30-50% reduction in child DD
safe storage: 21% reduction
hand washing with soap: 43% reduction
sanitation: 30% or more reduction
federal regulatory agencies responsible for food safety
USDA’s FSIS (food safety and inspection services)
meat, poultry, all forms of egg
FDA’s CFSAN (center for food safety and applied nutrition)
everything else
EPA’s OPPTS (office of prevention, pesticides, and toxic substances)
pesticides
CDC’s food safety office
food borne infections
role of state and local gov’t in food safety
on-the-ground inspections, esp. in restaurants and food prep sites
Food 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
HACCP (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
types 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)
food borne illness risk factors — defined by CDC, ex = food from non-approved sources, inadequate cooking temps/holding temps, etc
salmonella
bacteria spread through indirect or direct contact with intestinal contents or excrement of animals
- often associated with eggs, poultry, raw sprouts
- bacteria destroyed by cooking to 160*F; do not grow but DO survive in fridge/freezer
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
- grows best in reduced-oxygen environment and inhibited by salt, acid and drying
- will not multiply at temps below 85*F
sources of Campylobacteriosis
raw/inadequately cooked foods of animal origin
non-chlorinated water
preventative measures for Campylobacteriosis
pasteurize milk
cook raw meat
prevent cross contamination
infection vs intoxication
Infection caused by growth of pathogen – incubation 12hrs-2wks
Intoxication caused by ingestion of toxin – symptoms appear 1-48 hrs after infection
basic food safety practices
clean, separate, cook, chill
municipal solid waste (MSW)
refuse collected by municipalities from households, small businesses, and institutions
solid waste
any discarded solid material
non-liquid, non-soluble materials ranging from municipal garbage to sewage sludge; agricultural refuse; and mining residues
RCRA (Resource Conservation and Recovery Act)
pollution control; treatment (recover energy and reduce hazard)
- goal of this federal law is to prevent unsafe and illegal disposal of hazardous wastes on land
- enacted in 1976 to give EPA “Cradle to Grave” authority over hazardous waste
RCRA historical events
Times Beach — Russel Bliss sprayed waste oil onto dusty roads
CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) 1980
pollution control; disposal (permitted and proper)
- for poorly managed/abandoned waste sites
- gov’t or responsible party must clean up
- very tough law
We have an expert-written solution to this problem!
three traits of CERCLA law
retroactive — past and current owners liable
strict — liable regardless if all laws of day were followed
joint and several — one small waste generator can be liable for all
CERCLA historical context
Love Canal, Niagara, NY: toxic waste dumped in 30s-50s, waste oozes decades later
“Valley of the Drums” Louisville, KY: 17,000 openly dumped drums removed
SARA (Superfund Amendments and Reauthorization Act of 1986)
- requires emergency planning for spills and releases
- establishes Toxic Release Inventory (TBI)
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
EPCRA
Emergency Planning and Community Right to Know Act of 1986
RCRA regulatory scope
- you have 90 days of on-site storage from when last drop is added
- cannot “treat” HW; one drop of HW and whole thing is HW
- generator owns waste FOREVER!
- landfill and gas station requirements
RCRA hazardous waste tracking
- listed or characteristic
- manifest tracking for all RCRA waste; manifest returns to generator
Medical waste management act
origins in RCRA
National Priorities List (NPL)
list of contaminated sites maintained by EPA that are eligible for cleanup funds
CERCLA
3 types of workplace hazards
chemical
physical
biological
1980 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”
how are workplace chemicals regulated?
PELs or TLVs set limits to protect workers exposed 40 hours/week for 40 years
PEL (OSHA)
Permissible Exposure Limit
8 hour time weighted average
STEL
Short Term Exposure Limit
OEL
Occupational Exposure Limit
TLV (ACGIH)
Threshold Limit Values
8 hour time weighted average
IDLH
Immediately Dangerous to Life and Health
limit to where death may occur within 30 minutes
BEI
Biological Exposure Indices
bio-indicator of exposure
concentrations of chemical in bio fluid/tissue
what do first responders’ air sampling instruments detect? (4)
combustible gas
O2 levels 19.5-30%
hydrogen sulfur (sewer gas)
carbon monoxide
what is a cascade impactor?
a “stack” of plates that separates particles into stages of interest to diff locations in human lungs
bigger particles deposit on earlier/top plates and smaller make it to the bottom
what is the 8 hour TWA limit? (ACGIH)
85 dB
hazardous range = 90-140 dB
Confined Space Entry Standard
OSHA standard that requires space-entry restrictions, rescue procedures, and a written safe-entry program
confined space entry standards address concerns… (3)
…over adequate oxygen content in the air, toxic substance exposure, and physical exposures for workers in confined spaces
Work/rest cycles (2)
heat stress
not legally enforceable
WBGT
Wet Bulb Globe Temperature
measures heat + humidity for work/rest cycles
clo factor
1 = naked
1.1 = t-shirt and shorts
(no correction necessary)
heavier clothing means you drop temps you can tolerate
if wearing body armor, add _ *F to WBGT in humid climates
5
if wearing NBC clothing (MOPP 4), add _ *F to WBGT
10
ACGIH
American Conference of Governmental Industrial Hygienists
private org
pre-dates OSHA
OSH Act of 1970
established OSHA and NIOSH
each 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
NIOSH
National Institute for Occupational Safety and Health
recommends ways to prevent workplace injury
research
OSHA
Occupational Safety and Health Administration
legal authority
hierarchy of hazard controls (5)
elimination
substitution
engineering
administrative
PPE
examples of hierarchy of hazard controls
elimination — controlling hazard at source
substitution — replacing one substance or activity with a less hazardous one
engineering — installing filters, scrubbers, guards
administrative — procedures to reduce opportunity for exposure
PPE — respirators, ear plugs
STEL — when used? time period?
Short Term Exposure Limit
used when a chemical can harm within a short period of time (ex: cyanide)
max concentration allowed during a 15min continuous period, allowed 4x/day, 60min between
ceiling limit
maximum concentration of a material in air that should not be exceeded, even instantaneously
air purifying respirators + examples
use filters or cartridges to remove air impurities before they can be inhaled
never use in low O2, highly hazardous, or unknown environments
ex: disposable mask, half mask, gas mask
supplied air respirators + examples
pressure inside mask is positive to keep outside air from coming inside mask
come with own air supply
ex: SCBA, airline respirator
conditions for mold/mildew formation indoors
wet building materials
68-90*F
60% relative humidity
no air movement
how to control mold/mildew
keep humidity between 30-60%
penetrable + alpha radiation defenses
penetrable radiation: gamma, x-ray
- more time
- more distance
- more shielding
alpha radiation: outer covering; pose problem only if inhaled
three industries with highest fatality rate
construction
transportation and warehousing
agriculture, forestry, fishing, and hunting
high % of migrant workers
3 control strategies for repetitive motion injuries
reduce repetition
reduce force/weight
maintain near-neutral position
Understand 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
Homeostasis 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
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
Necrosis- cell damage and death, passive and disorderly; produces cell debris
Bacteria vs Virus
bacteria
-prokaryotic cell
-most are free living
-relatively large
-antibiotics used to kill
Virus
-not a living cell (genes packaged in protein shell)
-intracellular parasite
-1/1000 size of a bacteria
-vaccine used to prevent
-antiviral treatment
protein synthesis
the formation of proteins by using information contained in DNA and carried by mRNA
DNA transcription RNA translation protein
Role of DNA
storing information, copying information, and transmitting information
Role 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.
Role of tRNA in protein synthesis (translation)
is the key to diciphering the code words from mRNA
Role of ribosomes in protein synthesis
ribosomes are complexes made of ribosomal RNA and protein
ribosomes carry out protein synthesis in two locations
a 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.
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)
Gene-gene interactions: ○ 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
■ 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.
○ 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
■ 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
○ Epigenetics – the environment can alter your health by affecting the proteins that turns genes on or off
■ 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
Explain the role of the microbiome and its role in disease prevention
Microbiota → gut microbiota
- Involved in basic human biological processes
- Chronic disease have been associated with the human microbiota
Antibiotics can disrupt microbiota
The 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.
Epigenetics
the study of environmental influences on gene expression that occur without a DNA change
DNA methylation
The addition of methyl groups to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression.
histone modification
adding chemical modifications to proteins called histones that are involved in packaging DNA
micro-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.
Microlesions
change in 1 bp
substitution
point mutation (silent, nonsense, missense)
frameshift mutations
Macrolesions
chromosome aberrations
- Often caused by effects on mitotic machinery, not DNA
- Change in chromosome structure
- Deletion, duplication, inversion, translocation—may be stable
- Acentric fragments, dicentric chromosomes—usually cell death
change in chromosome number - aneuploidy
- polyploidy
Why do mutations matter?
● Polymorphisms can change the function of proteins
● Many proteins (e.g., enzymes, receptors) associated with response to chemicals, drugs, and so on
● Effect may be silent, advantageous, or disadvantageous
○ Example: Change in SNP can make people less drug dependent
genotoxic carcinogens
Causes DNA replication errors, point mutations, Chromosomal abberations, also binds to DNA and is irreversible
Nongenotoxic
carcinogens that modify gene expression but do not damage DNA
induce cancer through hormonal effects, cell proliferation, increase change of replication errors, increase number of cells at risk
mutations and cancer
Cancer-causing mutations typically occur in two categories of genes
proto-oncogenes: leading to altered forms of normal cellular genes usually involved in cell signaling and growth control
tumor suppressor genes: whose protein products help regulate proliferation of normal cells- act as a “brake”- or promote programmed cell death (apoptosis)
Three cancer types with highest mortality in the US
- lung/ bronchus
- colon/ rectum
- pancreas
innate vs adaptive immunity
Innate immunity: An individual’s genetically predetermined resistance to certain diseases.
Adaptive immunity: Ability of the body to react to specific microbial infection. ANTIGEN SPECIFIC
Antibody-Antigen Interactions
•Complementary fit between antigen and antibody is needed
•The better the fit the better the stimulation of the lymphocytes
Can be multiple antigens on one pathogen cell (can be proteins, sugars, etc), each recognized with a different antibody
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.
first 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.
Concentration of the drug is greatly reduced before it reaches circulation
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.
The liver converts fat soluble toxins to water soluble substances that an be excreted.
The enzymatic process to dispose of toxins happens in 2 phases: phase 1 (oxidation) and phase 2 (conjugation).
■ 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.
■ 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.
Variability in metabolism
can affect the activity of drugs
dose-response relationship
Relationship between an administered dose and the effect on an organism
majority of response are at mean
- Knowledge of the dose-response relationship establishes:
o Causality — that the chemical has induced the observed effects
o The threshold effect — the lowest dose where an induced effect occurs.
o The slope for the dose response — 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.
○ The variation can be due to genres, nutrition, health status, etc.
● Measures proportion of the population responding at each dose level or level of response at each dose level in controlled settings
Individual vs. population dose relationship
Individual dose response relationship: change in severity of adverse effect with dose (also called dose-effect relationship)
○ Example: Aspirin therapeutic in low dose and super bad in high doses (dose makes the poison)…BUT different ppl are more sensitive to aspirin (or other chemicals) that make the dosage effects vary
Population dose response relationship: change in the proportion of the population responding with dose
○ Different relationships for different effects
○ Shape of curve gives information about population variability and toxicity of the compound
pros and cons of toxicology and epi in determining toxicity
○ Epidemiology:
■ Study of disease rates in human populations with and without exposure to chemical under study
■ Can discover a statistical association between exposure and disease
■ Rarely can establish causal relationship or mechanism of disease causation
○ Strengths
■ Study species of interest
■ Free ranging subjects in their natural environment
○ Limitations
■ Nonexperimental
■ Often qualitative
■ Usually retrospective
■ Often high-dose occupational studies
● Environmental exposures are usually much lower
● May miss diseases of women, the young, or the elderly (if we focus only on the workforce of interest)
■ Subject to confounding and bias
NOAEL and LOAEL
No Observed Adverse Effect Level: Highest dose at which there was not an observed toxic or adverse effect.
Lowest Observed Adverse Effect Level: Lowest dose at which there was an observed toxic or adverse effect.
LD50
the amount of a chemical that kills 50% of the animals in a test population
shows how lethal a dose is
RfD
Reference Dose: Estimated daily dose that is likely to have no appreciable adverse effects during a lifetime exposure
An 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.
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.
mechanistic studies
■ In Vivo = ADME studies & effects of different dosing levels, durations, or patterns
■ In Vitro = Mutagenic potential, molecular mechanism of actions
■ Strengths:
● Compound-specific information
● Understanding biology should improves
○ Cross-species extrapolation
○ High-dose to low-dose extrapolation
■ Weakness
● Difficult to rule out alternative theories
● Often lack of necessary data for humans
● Scientific disagreement/uncertainty
acute toxicity
adverse effects that occur within a short period after exposure to a toxicant
chronic toxicity
adverse effects that occur some time after exposure to a toxicant or after extended exposure to the toxicant
Define absorption
movement of digested food molecules through the wall of the intestine into the blood
Define distribution
How the drug is transported by the blood to the site of action. It requires adequate cardiac output and tissue perfusion
Define 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.
Define excretion
Removal from organisms of toxic materials, the waste product of metabolism and substances in excess requirement
passive diffusion
movement of substances across a semipermeable membrane with the concentration gradient; this process does not require energy
hydrophobicity molecules can readily cross
facilitated diffusion
Movement of specific molecules across cell membranes through protein channels
active transport
Energy-requiring process that moves material across a cell membrane against a concentration difference
Primary routes of exposure
○ Oral: Leads to first exposure with organ absorption
○ Inhalation: air ways
○ Dermal: skin contact
Four steps of environmental risk assessment
- hazard identification
- Dose-response evaluation
- Exposure assessment
- Risk characterization
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
Dose-response evaluation
*an attempt to quantitatively determine the relationship between exposure to a toxicant and disease.
exposure 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
risk characterization
develops estimates of the number of excess unwarranted health events expected at different time intervals at each level of exposure
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.
world met MDG for improved drinking water, but not for sanitation
ground water quality
usually free of contaminants because the soil filters it and often available where needed at little cost
limited volume, essentially irreplaceable once depleted
wellhead protection areas protects groundwater by keeping any activity that can contaminate the groundwater out of the area where the aquafor is being accessed
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
Clean 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
NPDES
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.
Still require a permit to dump in navigable waterways, streams and intrastate lakes, coastal waterway, freshwater wetlands.
1987 amendment: attention to stormwater runoff “non-point” sources
Safe Water Drinking Act (1974)
set maximum contaminant levels for pollutants in drinking water that may have adverse effects on human health
requires the EPA to publish a list of unregulated contaminants of concern list (CCL)
Contaminants of concern
Specific contaminants that are of concern for human health for the exposure pathway
EPA must show:
- That the contaminant adversely affects human health
- that it is known or substantially likely to occur in public water systems with a frequency and at levels of public health concern
- that regulation of the contaminant presents a meaningful opportunity for health risk reduction
MCLGs
Maximum Contaminant Level Goals (nonenforceable): a nonenforceable publish health goal
- After reviewing health effects studies, the EPA sets a Maximum Contaminant Level Goal (MCLG)—a nonenforceable public health goal.
- At level where no adverse effect expected
- Drinking water consumption compared with an oral reference dose (RfD) and other potential sources of exposure to contaminant
- MCLG for suspect carcinogens set at zero
- Does not consider ability to measure or treatment technology
- Once the MCLG is established, the EPA sets an enforceable standard called a Maximum Contaminant Level (MCL).
- Based on technical feasibility and cost
- Set as close to the MCLG as possible
- 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—still enforceable.
- Technology or procedure (performance standard) that must be followed
- Example is the lead and copper rules that monitor tap water and compare it with an action level, rather than an MCL
MCLs
Maximum contaminant levels (enforceable): maximum amount of any water pollutant that might adversely affect human health
primary vs secondary drinking water standards
NPDWR: primary are legally enforceable standards (MCLs and treatment techniques)
NSDWR: unenforceable guidelines (cosmetic effects and aesthetic effects)
explain typical water treatment processes in developed countries including disinfection by-products
- Screen, usually surface water only
- Flocculation / coagulation: chemicals that are used to clump fine particles together. Particles stick and grow big enough and eventually settle out.
- Sedimentation: all the particles stuck to flock are removed through gravity
- filtration: activated charcoal takes chemicals and other things out of water by binding to them
- disinfection
- storage
- Distribution of water
Disinfection
Chlorine: cheap effective, produces a number of by-products
Ozone: expensive, no residual
Chlorine dioxide: no residual
Explain water availability and treatment challenges in developing countries
○ Arsenic in drinking water, need to dig deeper wells; filtration techniques; mark high arsenic wells
■ Bangladesh example of attempts to reduce surface waterborne disease…dug tube wells…lead to massive arsenic exposure in the population (Persons w/poor nutrition esp sensitive to arsenic effects)
■ 2/3rds of wells have high arsenic levels
○ 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.
○ Water availability –> proportion of population using an improved drinking water has improved but disparities exist especially between rural and urban.
○ Treatment challenges : Done at household level.
■ Chlorination – appropriate for use in areas where drinking water is taken from muddy ponds or rivers.
■ 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.
■ 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.
■ Boiling- potential for recontamination after boiling and prior to consumption is high. Water must be consumed in 24 hours.
point source vs. non-point source pollution
Point source pollution is when contaminants enter a water supply from a single identified source
non-point source pollution is when contaminants cannot not be traced to a source (example: animal manure/ stormwater)
Biological Oxygen Demand (BOD)
The amount of oxygen needed by microorganisms to decompose biological wastes into carbon dioxide, water, and minerals.
Higher 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.
apply systems thinking to explain why marine “dead zones” develop
○ Hypoxia – Low Oxygen.
○ Anoxia- no oxygen.
○ 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.
Explain the function of each stage of a wastewater treatment facility.
Coming out of your house—>connected to a larger sewer system & wastewater treatment facility.
- Primary: First step is to run it through coarse screens- capturing grit. Grits goes to landfill by truck
- 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
- 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
- Final settling Tank—>sludge again is collected and then get treated water.
- Sometimes can go to tertiary treatment where the water is disinfected. Tertiary treatment may be used to remove nutrients or reclaim water
- Sludge Disposal (8 million tons of sludge a yr) — 60% is used in fertilizer and soil amendments Landfill Incineration Ocean dumping—now banned in the United States
- 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
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.
Describe the types of interventions to address water, sanitation and hygiene (WASH) as it relates to the global burden of disease.
Water- drinkable water
■ Intervention: piped water into dwelling, yard, or plot, public tap or standpipe, protected dug well (groundwater), rainwater collection, protected spring water.
Sanitation refers to getting rid/maintaining human waste.
■ Intervention: composting toilet, pit latrine with slab, ventilated improved pit (VIP) latrine, Flush or pour-flush to: –> piped sewer system, septic tank, pit latrine.
Hygiene – thorough handwashing before eating and after using the toilet
■ Intervention: Need Access to community water systems, Sanitation facilities, household-level and materials and technologies
■ Intervention: changes in behavior practices—> social marketing, school programs, community participation and mobilization.
■ Intervention: enabling environments—> Policy improvements, community organizations, Institutional strengthening, Financing and cost recovery, Public-private partnerships.
■ All interventions must occur to improve hygiene.
It 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.
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.
Explain 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
HACCP (Hazard Analysis and Critical Control Points)
■ Systematic approach to food safety through prevention, rather than inspection offinal product
■ Origins in systems analysis and NASA—now used worldwide for food safety
■ Map production process and identify “critical control points”
■ Thorough record keeping critical to verification and continuous improvement
■ FDA HACCP Guidance
Local Government Role in Food Safety
■ Inspections of food-producing establishments by local health departments is a key public health measure.
■ For example, the Washington, DC, Health Regulation and Licensing Administration includes the Food Safety and Hygiene Inspection Services Division.
● 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
● The staff for the program includes 17 sanitarians, two supervisors, a program manager, and a food technologist
DC Health Regulation and Licensing Administration
■ Inspect for proper handling and preparation and other food safety practices as well as potential health hazards
■ Violations can be corrected on site (COS) or within a specified period—inspected again to confirm
■ Understanding DC Food Safety Reports
Salmonella source
Raw and undercooked eggs, poultry, meat, fish; unpasteurized milk.
often 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.
Salmonella health effect
The bacteria are spread through indirect or direct contact with the intestinal contents or excrement of animals, including humans.
Salmonella 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.
Campylobacteriosis source
■ 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.
■ 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).
Campylobacteriosis symptoms
Fever, headache, myalgia –> severe abdominal pain –> bloody/watery diarrhea
3-7 day duration
Campylobacteriosis protective measures
■ 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.
■ 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.
infection vs intoxication
infection is microbes grown in GI tract and can become a systemic infection often causing fever
intoxication is microbes located in food that produce toxins and have rapid onset
○ Infection vs. intoxication
■ Salmonella, Campylobacter, E. coli, and Listeria bacteria in food cause food infection.
■ Staphylococcus and Clostridium botulinum bacteria produce a toxin (or poison) as a by-product of growth and multiplication in food and cause food intoxication.
○ Salmonella and Campylobacter are two of the most common sources of human foodborne disease found in CDC FoodNet program
● Explain issues/conditions that challenge food safety and some basic food safety practices
○ Types of Violation in Food Safety Inspection
■ 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
■ 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
■ 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
○ Learning About Local Practices
■ In Virginia, all restaurant inspections, including specific citations and reactions, posted online: Virginia Department of Health’s Inspection Database
■ DC has searchable database of food inspections: Health Regulation and Licensing Administration
■ Montgomery County, Maryland: Data Montgomery – Food Inspection
solid waste
any discarded material from industrial, commercial, govt, mining and agriculture; including solid, semi-solid, liquid, or contained gaseous material
hazardous waste
Any material that can be harmful to human health or the environment if it is not properly disposed of
Two types:
○ listed or characteristic
■ Listed
● Non-specified sources -> toluene, MEK, etc
● Specific sources -> sludge from steel making plant
■ Characteristic – toxicity, ignitable, reactive, corrosive
Municipal solid waste
the waste materials produced in homes, businesses, schools, and other places in a community
■ EPA does not manage at household level, but regulates landfills, etc
Resource Conservation and Recovery Act (RCRA, 1976) History
Times Beach, MO
● 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
● Waste oil contained dioxin, which is a toxin
● EPA realized this and declared a health emergency
● RCRA law passed in 1976
● 1982 flood hits Times Beach → CDC recommends to not re-inhabit
● Town is de-incorporated after incinerator burns 250,000 tons of soil in 1995
Resource Conservation and Recovery Act (RCRA, 1976) Scope
● Defined waste as a technical term (see definitions above)
● Main Intention of RCRA: to disincentivize companies from trying to handle their own hazardous waste; how do we prevent accumulation of hazardous waste?
○ 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
● Exclusions: domestic waste, fossil fuels, mining wastes, oil and gas refining waste, hydrofracking
● Subtitles A-J of the law classify various kinds of RCRA waste:
○ Subtitle C: Hazardous Waste “Cradle to Grave Tracking”
■ “Cradle to Grave” – making sure the hazardous waste from an industrial company actually gets dropped off at an EPA facility
■ Ex – following a truck that is carrying the waste from the factory to the facility to make sure the waste is properly disposed of
○ Subtitle D: Non-Hazardous Wastes (Municipal Landfills, etc)
○ Subtitle F: Fed Responsibilities (waived sovereign immunity)
○ Subtitle I: Underground Storage Tanks
○ Subtitle J: Medical Waste (now under Medical Waste Management Act)
● Other Important Details
○ RCRA waste is way more expensive to dispose of than regular municipal waste
○ Mixtures – if one drop of Hazardous waste in barrel, it’s all hazardous waste
○ Cannot store waste for more than 90 days on site
○ You cannot “treat” hazardous waste
Every container MUST be properly labeled for disposal with detail on the contents
Comprehensive Environmental Response Compensation and Liability Act (CERCLA) History
● Love Canal, City of Niagara, NY
○ 1930s-1950s – Hooker Chemicals dumps ~21,000 tons of Toxic waste into land
○ 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)
○ 1960s – homes and schools were built near site
○ 1978 – waste found oozing from the ground
○ President Carter declares Federal Health Emergency
○ 1980 – CERCLA Law Passed
● “Valley of the Drums” near Louisville, KY
○ Publicized Love Canal was suburban neighborhood; valley of the drums was more visual
○ 17,000 openly dumped drums were removed from 13 acres
○ 1966 – several barrels burned for weeks – still ignored
○ 1979 – EPA issues Emergency cleanup
○ 1980 – CERCLA Law Passed
We have an expert-written solution to this problem!
CERCLA Scope
● Details of Law
○ National Priorities List (NPL) – hazardous waste sites based on health hazard ranking system
○ Government responsible parties MUST cleanup
○ Very Tough Law – Polluter Pays
■ Retroactive – all past and current owners liable
■ Strict – liable regardless if all laws of the day were followed
■ Joint and several – one small waste generator can be liable for all
○ 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
● When a company no longer exists to be held responsible for its waste, EPA pays (so that means the taxpayers) → budget is ~$250 mil/year, but we need a LOT more to actticually make progress
Superfund Amendment Reauthorization Act (SARA) History
● Bhopal, India – 1984
○ Former DOW chemicals had a Carbide Pesticide plant in India
○ “Worst Industrial Accident” in history – at midnight, 42 tons of Methyl Isocyanate (MIC) reacts with water, over pressurized tank, released into the air
○ Thousands of people wake up with burning sensation in eyes, lungs, etc.
○ Death toll under dispute – anywhere from 4,000-25,000
○ 10,000+ with long term effects
● Outrage over Bhopal lead to SARA
Superfund Amendment Reauthorization Act (SARA) Scope
● Details of Law
○ Created Emergency Planning and Community “Right to Know Act” (EPCRA) – citizens have a right to know about chemicals in the community
○ Requires emergency spill and release response
○ Established the Toxic Release Inventory (TRI)
■ Must report all chemical releases, storage, usage, disposal, (above certain reportable thresholds)
■ Publically available – powerful incentive to reduce emissions
Describe the health impacts for the globalization of waste management (e.g. recycling overseas etc)
○ 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
○ These landfills abroad also can sometimes overflow into the surrounding bodies of water with enough rain/floods leading to water pollution
○ All of this pollution leads to large negative health impacts on citizens
● Other Helpful Graphics/slides for this Lecture
American 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.
OSHA (Occupational Safety and Health Administration)
■ To assure so far as possible every working man and woman safe and healthful working conditions … no employee will suffer diminished health, function or life expectancy from work
■ OSHA – Occupational Safety & Health Admin – legal authority – set rules
■ NIOSH – National Institute of OSH – research to help figure out standards. OSHA decides to pursue what NIOSH suggests
■ OSHA can be sued
○ 1970 – OSHA adopts 1968 ACGIH Exposure Standards
Match any control strategy into the hierarchy of hazard controls
Elimination: controlling the hazard at source
Substitution: replacing one substance or activity with a less hazardous one
Engineering: installing filters, scrubbers, guards
Administrative: procedures to reduce opportunity for exposure
Personal Protective Equipment: respirators, ear plugs
Explain the difference between 8-hour PELs/TLVs, STELs/Ceiling Limits and IDLH
○ We regulate workplace chemicals by setting PELs or TLVs – limit set to protect adult worker exposed 40 hours per week for 40 yrs
■ OSHA – PELs
■ ACGIH – TLVs
■ TLV: threshold limit values…ACGIH limit, so scientifically sound but not legally enforceable
■ PEL: permissible exposure limit: OSHA value
● Both TLVs and PELs use either ceiling limits (max concentration allowed…denoted by c next to number) or 8 hour time weighted average (used for most chemicals with long-term toxicities)
■ Most shifts are 8 hours, avg exposure is compared to standard. If below, you are OK
■ Ceiling limit: highest limit, can’t go over this limit ever!
Air Purifying Respirators vs. Supplied Air Respirators
○ Respiratory Fit Test Program is critical for worker education and assuring a proper seal
■ Air Purifying Respirators – must use the nearby air (never use in low oxygen, highly hazardous or unknown environments)
● Disposable Masks Half Mask Full Facepiece Gas Mask
■ Supplied Air Respirators – comes with their own air supply
● Airline Respirator, Self Contained Breathing Apparatus (SCBA)
● Emergency Escape Only when escape will take time – good for 5-10 min
○ Respirator only protects user and mask protects everyone else
○ Asbestos removal requires encapsulated area, suits with respirators and constant air sampling
Explain the conditions for molds/mildew formation indoors
Molds/Mildews love wet building materials, 68-90F, rel humidity >60%, no air movement
We basically control by keeping humidity between 30-60%
Measuring ventilation is a key aspect of controlling indoor air pollution, chemicals, mold etc
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
Confined Space Entry, Have standby worker, alarm horn, emergency SCBA, lifeline to safety harness, gas and fume extractor, Heat Stress, Radiation Workers
■ For penetrable radiation (gamma), your only defenses are: More Time, More Distance, More Shielding
■ Outer covering is mainly for alpha particles that pose a problem only if inhaled
Lasers: can even be used as weapons of mass destruction (Temperature: wet bulb global temperature (WBGT))
All Values in WBGT (wet bulb globe temperature), which takes humidity and solar radiation into account
Name the three industries with the highest fatality “rate”
Construction, transportation/warehousing, agriculture/forestry/fishing/hunting
Ergonomics
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.
○ Primary control methods are:
■ Reduce repetition (times/day)
■ Reduce force/weight
■ Position – maintain near neutral
Discuss the ethical impacts of poor occupational health programs in developing countries
○ Worldwide Worker Mortality
■ International Labour Organization (ILO) estimates 2.3 million people die from at work each year (6000/day)
■ ILO estimates 340 million occupational accidents per year (nearly 1M/day)
■ Record keeping is poor in many countries and there is a lot of underreporting (if it’s not measured, it will not be fixed)
○ 1129 garment workers killed in 2013 from collapse of the Rana Plaza in Bangladesh
■ Garment industry pays ~$1/hour and basically moves into poor countries
■ 80% were female aged 18-20
■ 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.
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