PUBH6011 Final Prep

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School

George Washington University *

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Course

6011

Subject

Biology

Date

Dec 6, 2023

Type

pdf

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Uploaded by ConstableSteel12915

Outline from Week 6 to Week 10 1. Understand the major functions of cells and the difference between viruses and bacteria. Answer: The cells is the basic unit of all living tissue. Bacteria are layered; they are multilayered gram-negative bacteria have a peptidoglycan layer and a lipid layer. Viruses are either naked or enveloped. viruses are microbes that are not alive. They do not respirate on their own. They take over a cell molecular machinery and make it do things that it would not do naturally. Viruses are smaller than bacteria. 2. Explain protein synthesis and the role of DNA, mRNA, tRNA, ribosomes. Answer: DNA: (deoxyribonucleic acid) DNA is found in the nucleus of the cell. DNA is The building block of the chromosome. DNA has 3 main components; nucleotide bases (ATGC), phosphate backbone (PO4-), sugar. Each cells has 6 feet of DNA. DNA are wrapped up in histones. A gene is DNA that encode the sequence for protein. DNA possesses introns that makes some DNA non coding. DNA gene sequence acts as a template for mRNA. mRNA leaves the nucleus and goes to the cytoplasm, in the ribosome to be exact. tRNA are in the ribosome. tRNA are sequence for a specific amino acid. tRNA carries the amino acid to the ribosome. 3. Explain how biology and genetic factors can influence our response to environmental hazards. Answer: infectious agents, oxygen deprivation, trauma, chemicals, nutritional imbalances, inflammation can lead to cell death. 4. Explain the role of the microbiome and its role in disease prevention. Answer: microbiome is more medically accessible and manipulable than the human genome. 5. Explain how environmental factors influence genetic expression (i.e., epigenetics) Answer: DNA is the same in all cells in our body. epigenetics determines which gene are expressed. Epigenetic changes are passed down from family to family. Epigenetics change over time due to the environment. Epigenetic modifications can be transferred from generation to generation. Three mechanism of epigenetics: DNA methylation, Histone modification and micro-RNAs. DNA methylation is adding a methyl group to the DNA code. It suppresses gene expression by inhibiting transcription. DNA methylation may mediate the relationship between air pollution exposure and cardiovascular disease. DNA is wrapped around histones and inhibits replication and transcription to happen. Acethyl groups is attached to the DNA so that histones can be released and promote transcription. 6. Explain various types of genetic mutations that can occur Answer: insertion is a replication error where a base is mismatch with another one. Proofreading and repair enzymes -frameshift mutation changes 7. Explain the difference between genotoxic versus non-genotoxic carcinogens (i.e., initiator/promoter)

Answer: all cancer is believed to result from the mutation of specific genes. carcinogens require cells that can be divide. Red blood cells cannot be divided because they do not have nucleus. genotoxic carcinogens: also called mutagens are able to directly, or with metabolic activation, alter DNA. They cause point mutation(change the DNA sequences), Chromosomal aberrations(damage the structure of chromosomes). Non-genotoxic carcinogens: do not directly alter DNA but may not increase cancer risk. Increase chance of replication errors, increase number of cells at risk. 8. Know the three cancer types in the US that cause the highest mortality. Answer: liver, corpus and uterus, thyroid 9. Explain the difference innate vs adaptive immunity. Answer: innate immunity: it does not care what the invader is. It take a couple of hours to act. Physical barrier helps prevent entry (skin, mucous membranes, stomach acid). Specific cells attack invaders. Adaptive immunity: helps fight something that your immune system already knows. It takes days to act. The immune system being able to distinguish self from non self is key. Detect molecules (usually proteins) on the surface of cells. 10. Explain the antibody/antigen reactions and the types of defense reactions they trigger. Answer: antibody: proteins that are coded in genes. Recognize specific antigen within great specificity. T cells (killer cells) and B cells makes antibodies to fights a specific antigen. Antigen: substance that can provoke an immune response. 11. Explain how vaccines use the body’s natural immune system to protect from diseases. Answer: create antibodies and memory. 12. Explain the importance of herd immunity in protecting a population from the spread of disease. Answer: Herd immunity is adding people who are immune to a disease that would not be able to transmit the disease in a population. Herd immunity is gotten by people being vaccinated. 5The transmission rate decrease when people are vaccinated. 12. Explain the biological mechanism of digestion and the first pass effect Answer: Food is breaking down mechanically, by chewing the particles and chemically using enzymes, salivary amylase breaks down the starch and sugar. The food molecules move through the esophagus that contracts and relaxes (peristalsis) to allow the food to move to the stomach. The stomach has chemicals to further break down the molecules (protein, fat and sugar) and smooth muscles that contract and relax to allow food molecules to move to the small intestine. In the small intestine, food continues to break down by enzymes, bile, and hormones and nutrients are absorbed into the bloodstream. The villi and microvilli of the small intestine increase surface area to absorb more nutrients. Once the nutrients are in the bloodstream, the circulatory system transport them to all the cells in the body. Large intestine absorbs excess water from undigested food. Waste from cells are excreted from the excretory system (urine). Undigested material is eliminated from the body as solid material by the digestive system. First pass

effect leads to high concentration of materials absorbed through the GI tract in passing through the liver. 13. Explain the role of liver in breaking down food, microbes and chemical toxicants Answer: The liver has extensive metabolic capacity that may alter form and activity of ingested molecules. 14. Explain how different people may handle toxicants differently based on enzymatic makeup Answer: variability in enzyme levels and activity between people can affect the activity of drugs. Different type of people have different metabolic rates from ultrarapid (rapid rate of metabolism), extensive (normal rate), intermediate (reduced rate), and poor (slow rate). Variability can be due to gene, nutrition, health status, etc. 15. Discuss pros and cons of toxicology and epidemiology in determining toxicity Answer: epidemiology can discover a statistical association between exposure and disease. On the other hand, rarely can establish causal relationship or mechanism of disease causation. Cannot tell how exposure can cause a disease. Toxicology studies the adverse responses caused in biological systems caused by physical or chemical reagents. Pros Cons Epidemiology ● Study species of interest (study human being in their natural habitat) ● Free ranging subjects in their natural environment ● Nonexperimental (cannot chose who to expose) ● Often qualitative ● Usually retrospective (something bad already happened) ● Often high dose occupational studies (usually focus in 1 population) ● Subject to confounding and bias Toxicology ● Well controlled experiments (controlled dose, no cofounding exposure) ● Prospective (can be tested before exposure) ● Generalization across species ● High dose to low dose extrapolation ● Definition of response

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16. Define key toxicology terms and concepts (e.g.,NOAEL, LOAEL, LD50, RfD, slope factor, etc.) Answer: NOAEL: no observed adverse effect level: the highest dose administered that does not produce a statistically significant increase in an adverse effect. LOAEL: low observed adverse effect level.: the lowest dose tested that produces a statistically significant increase in an adverse effect. LD50: lethal dose to 50% of the population. It is used to compare relative acute toxicity of different substances. RfD: reference dose: an estimate of the daily exposure to the human population that is likely to be without an appreciable risk of deleterious effects during a lifetime Slope factor: give an estimate of increase in cancer risk per mg/kg/day of average daily dose. 17. Differentiate between acute and chronic toxicity Answer: acute toxicity is things that happened in a short period of time (poison). Acute toxicity is the sudden onset of toxic effect (hours or days), usually from a single dose, often reversible. sub-chronic toxicity might occur to human from weeks to months to a year of exposure. Chronic toxicity is a long time of exposure (more than 1 year). Chronic toxicity: toxic effect seen after a long term (years) exposure; results of prolonged exposure, usually lower dose than acute. 18. Describe absorption, distribution, metabolism and excretion Answer: the chemical is absorbed (through inhalation, dermal contact or ingestion). Glycolipids Molecules move through the cell membrane(lipid bilayer) of the cell. The movement of molecules is made through three different ways. Passive diffusion let some molecules transfer from high to low concentration with no energy needed. The molecules that move through the membrane depend on size, charge and hydrophobicity. Facilitated diffusion works via protein pores or carrier protein to help molecules get through the membrane that would not get through. Active transport require energy (ATP) to move molecules from the cell membrane against the concentration gradient. molecules distributed throughout the body by blood ( distribution ) and sometimes lymphatic system. During distribution, molecules may be processed by internal organs or they may pass through directly. As blood passes through organs and tissues, chemical may be transferred, depending on the property of the organ and the chemical. Metabolism will change the structure of the chemical and the elimination or excretion would get rid of the chemical. Two primary systems for elimination: phase I reaction-will react with different chemicals and add polar groups; Phase two reactions make conjugation to make molecules bigger and less reactive. . elimination happens through to GI tract or the bladder 19. Characterize the primary routes of human exposure (oral, inhalation, dermal) Answer: 20. Define the four steps of environmental risk assessment Answer: hazard identification: what are the adverse effects? What harmful effects is the agent capable of causing? At what dose are the effects seen? Dose-response evaluation: how much does it take for adverse effects?, quantity taken into the body.

Exposure assessment: how much people take in?What are the sources and pathways of exposure? Risk characterisation: estimate the magnitude of risk and uncertainty 21. Explain the difference in risk assessment logic for carcinogens and non-carcinogens Answer: non-carcinogens risk assessment: identify available data, evaluate endpoint and dose response relationship, choose critical effect in critical study, identify point of departure for critical effect. 22. Interpret hazard severity based on cancer slopes and RfDs Answer: 23. Familiarize with the philosophy of the UN Sustainable Development Goals (SDGs). Answer: the sustainable development goals agreed goals to transform the world by 2030. 24. Explain the difference in drinking water quality between ground and surface water sources. Answer: groundwater is free of contamination, bacteria, viruses, suspended solids, chemicals. It can be contaminated through human activity, source protection. Surface water is contaminated with pathogens (protozoa, bacteria, viruses, etc.). The pathogens are not due to human activity, they are from nature. 25. Describe the major features of the Clean Water Act (e.g., NPDES) and the Safe Drinking Water Act (e.g., MCLs, MCLGs). Answer: the national pollutant discharge elimination system (NPDES) permit program set water quality standards for surface water (chemicals, BOD, temperature, PH level). The maximum contaminant level goal (MCLG) is a unenforceable public health goal set by the EPA. At this level, no adverse effect is expected. MCLG for suspect carcinogens are set at 0. Once the MCLG is set, the EPA sets an enforceable standard called maximum contaminant level (MCL) based on feasibility and cost. If there are no reliable method to measure contaminant at a low enough level, the EPA may set an enforceable treatment technique (TT) instead of a MCL. 26. Explain the difference between a primary and secondary drinking water standards. Answer: the national primary drinking water regulation (NPDWR) or primary standards are legally enforceable standards (for example, maximum contaminant levels, treatment techniques). The national secondary drinking water regulation (NSDWR) or secondary standards are nonenforceable guidelines (cosmetic effects (skin or tooth discoloration), Aesthetic effects(taste, color, odor)). 27. Explain typical water treatment processes in developed countries including disinfection by-products Answer: surface water goes into a water plan (screen) to remove the debris from the water. Then moves to flocculation (aka coagulation) where chemicals (coagulants) are added to remove additional debris from the water. Next, the water moves to sedimentation stage where flocs is removed from the water. While moving into the sedimentation stage, gravity removes the big debris from the water. Then the water is processed through filtration where sand/ gravel or activated charcoal gets water clean. Last but not least, disinfection is the stage where chemicals are used to treat water to

increase protection against pathogens (protozoa, bacteria, viruses) at water plants and in distribution. Reaction between disinfection agents and organic compound found in water results in disinfection by products(DBP). 28. Explain water availability and treatment challenges in developing countries Answer: 29. Describe the difference between point source and non-point sources of water pollution Answer: non point source is polluted runoff from land (pathogens, nutrient, toxics) brought to the surface water by rain water. It is not regulated by NPDES. Point source pollutant is regulated by NPDES. 30. Explain Biological Oxygen Demand (BOD) and how it’s used to characterize the quality of water Answer: the biological oxygen demand is commonly used to measure nutrients. Oxygen demand comes from microbes metabolizing nutrient. Compare dissolved oxygen levels in water as sampled and after 5 days(higher nutrient levels will mean more biological activity and more oxygen used. 31. Apply systems thinking to explain why marine “dead zones” develop. Answer: dead zones are areas where nutrients have led to eutrophication of water bodies. 32. Explain the function of each stage of a wastewater treatment facility. Answer: 33. Explain the challenges of wastewater management in developing countries. Answer: 34. Describe the types of interventions to address water, sanitation and hygiene (WASH) as it relates to the global burden of disease. Answer: The millennium development goal is a goal of 7 was set for WASH. Target 7C was set to decrease the proportion of people living without sustainable access to safe water and sanitation, by 2015. Point of use water treatment, safe storage, hand washing with soap, and sanitations. 35. Explain the fecal-oral route of disease transmission and preventative measures Answer: feces can be spread by fluids, hands, flies, fingers, floors, and it can be spread by food. water: safe and uncontaminated water Sanitation: provision of facilities and services for safe disposal of human urine and fecal matter Hygiene: hand washing before eating and after using the toilet. 36. Explain the role of the various regulatory agencies responsible for food safety Answer: 37. Identify the source, health effect and protective measures for Salmonella and Campylobacter Answer:

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38. Explain the difference between infection and intoxication Answer: 39. Explain issues/conditions that challenge food safety and some basic food safety practices Answer: 40. Explain terminology such as solid, hazardous, municipal waste Answer: solid: any discarded material from industrial, commercial, government, mining, and agriculture, including solid, liquid, semisolid, or contained gaseous material. Hazardous: Listed or Characteristics solid waste Listed: - nonspecific sources: toluene, MEK, and so on; specific sources: sludge from steel-making paint Characteristic: toxicity, reactive, ignitable, corrosive Municipal waste: domestic wastes; i.e.: banana peels, soda cans, apple cores, etc. 41. Describe the historical events leading to the RCRA, SARA and CERCLA waste management laws Answer: RCRA was preceded by time beach missouri. Time beach missouri was a town with a population of 2000 is now a ghost town. From 1972 to 1976, Russell Bliss was hired to spray waste oil into dusty roads. Waste oil was mixed with dioxin laden waste from pharmaceutical companies. EPA declared a health emergency. As a result, RCRA law passed in 1976. Love canal in the city of Niagara, New York. Hooker chemicals dumps 21,000 tons of toxin waste. The land is then sold to the city for $1. Hundreds of homes are built near the site. Then waste was found oozing from the site and everybody panics. President Carter declares a federal health emergency. Many other dump sites were discovered after this. Valley of the Drums near Louisville, Kentucky. 17,000 openly dumped drums are removed from 13 acres. Several barrels were burned for weeks and was ignored. EPA issued an emergency clean up. CERCLA was created in the result of the two incidents. 42. Explain the regulatory scope written into the RCRA, SARA and CERCLA Answer: RCRA: laws that regulates industrial waste (how to manage a waste from occurring). Gives EPA the authority to control hazardous waste from "cradle-to-grave." This includes the generation, transportation, treatment, storage, and disposal of hazardous waste. - Solid waste management program - Hazardous waste: have 90 days of onsite storage (from the last drop is added) - Cannot "treat" the waste - Mixtures: if one drop of hazardous waste in barrel, it's all hazardous waste - Every container must be labeled Exclusions to RCRA include domestic waste, fossil fuels, mining wastes, oil and gas refining waste, hydrofracking and coal ash (4000 tons/day/coal plant) SARA: Citizens have a right to know about chemicals in their community. It requires emergency planning for spills and their releases. Established the TRI (Toxic Release

Inventory). The TRI says companies must report all chemical releases, storage, usage, disposal (above certain reportable thresholds). These reports are publicly available and serve as a powerful incentive for companies to reduce emissions. CERCLA: How to handle the mess that occurred. Also known as Superfund. For poorly managed or abandoned waste sites. Government says that the responsible party(s) have to clean up these sites, even if they are no longer in business, no longer located there, and followed all the current laws at the time. National Priorities List (NPL) - this locates hazardous waste sites. It is based on a health hazard ranking system. There are over 1600 NPL sites in the country. 43. Describe the health impacts for the globalization of waste management (e.g. recycling overseas etc) Answer: Hazardous waste workers often lack adequate PPE and training, which puts their health and safety at risk. Many may not be protects from exposure to lead, asbestos, polychlorinated biphenyls, mercury, and other hazardous materials during ship dismantling operation. 44. Explain the roles/responsibilities from the various organizations involved with occupational health Answer: 45. Match any control strategy into the hierarchy of hazard controls Answer: In order from most desirable to least desirable: - Elimination: controlling hazard at the source (chemical, noise, etc) - Substitution: replacing one substance or activity with a less hazardous one - Engineering: installing filters, scrubbers, guards, etc. - Administrative: procedures to reduce opportunity for exposure - PPE: respirator, ear plug, gloves, etc. 46. Explain the difference between 8-hour PELs/TLVs, STELs/Ceiling Limits and IDLH Answer: Permissible Exposure Limit (PEL): the maximum legal limits established by OSHA for regulated substances. These are based on employee exposure that is time weighted over an 8 hour work shift. When these limits are exceeded, employers must take proper steps to reduce employee exposure. Threshold Limit Value (TLV): Amount of a chemical substance is believed to be a level to which a worker can be exposed day after day for a working lifetime without adverse effects. Short Term Exposure Limit (STEL): Maximum concentration allows during a 15-min continuous period (allows 4 times per day, 60 minutes between) Ceiling Limits: Maximum concentration allowed at any length of time. Used when a chemical can harm within a short period of time. Immediately Dangerous to Life and Health (IDLH): Limit to where death may occur within 30 minutes. Mainly used in emergency response. 47. Explain the difference between the two types of respirators and when they should/should not be used Answer: Air Purifying Respirator (APR): Must use the nearby air (never use in low oxygen, highly hazardous or unknown environments) ex) Disposable mask, half mask, full face piece, gas mask

Supplied Air Respirator (SAR): Comes with their own air supply. ex) airline respirator, self-contained breathing apparatus (SCBA), emergency escape (only when escape will take time - good for 5-10 min) 48. Explain the conditions for molds/mildew formation indoors Answer: - wet building materials (carpet, drywall) - a temperature btw 68-90 degrees F - relative humidity > 60% - no air movement Mold/milder is controlled by keeping humidity between 30% and 60% 49. Discuss the various types of physical workplace hazards and approaches to protect workers Answer: Noise: - the 8-hour time-weighted average is 85 dBA according to ACFIH - Protective measures: use ear plugs or earmuffs. First step would be to see if it can reduce noise at the source. ex) quieter drill or engine Confine Space Entry: - a small location that slow down egress - your whole body doesn't have to be in the space, only your head to be considered a confined space ex) manhole, sewer line Protective measures: workers in space must be tethered, so they can be pulled out without outside worker entering the confined space. Additionally, there is two-way communication to be able to monitor the worker's speech to ensure no slurring which indicates chemical hazard. Before entering the confined space, air is sampled at various strata to ensure no chemical hazards present. Air is brought in through fresh air ventilation Radiation: Protective Measures: For penetrable radiation (gamma), your only defenses are:- Decrease the time of exposure; Increase distance from radioactive source, Increase shielding. Outer covering are more important for alpha radiation particles that pose a problem only if inhaled. 50. Name the three industries with the highest fatality “rate” Answer: Construction, Transportation and warehousing, Agriculture, forestry, fishing and hunting 51. Explain the three control strategies for repetitive motion injuries (ergonomics) Answer: - reduce repetition (times/day) - Reduce force/weight - Position - maintain near neutral 52. Discuss the ethical impacts of poor occupational health programs in developing countries Answer: - Terrible working conditions: Feature physical/verbal abuse, forced overtime, unsanitary conditions, denial of paid maternity leave, failure to pay, and long hours with no breaks - US industries (esp. Garment industry) contribute to this by going to countries with low costs, and hopping to new countries when costs rise. Ex. Rana Plaza incident in Bangladesh -1129 Garment workers killed in collapse - Additionally, workers often turn to be women and young, and the societal value of women is low. Additionally, managers tend to be men so gendered power dynamic

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