Exam 1 Flashcards
What is a hazard?
An agent that has a negative impact on human health or the surrounding environment
What is the water cycle?
The continuous movement of water where the sun is the source of energy that drives the cycle
As water moves through the environment, it is subject to contamination from the environment through the water cycle
Describe how surface water can be contaminated
Surface water generally becomes contaminated through the surrounding environment
Range of hazards rather than one type of hazard due to environmental variability
Describe groundwater
Fills the spaces between particles and fractured bedrock contained in an aquifer; 50% of people in US (rural areas) use groundwater as their water source
How is groundwater replenished? How is it contaminated?
Groundwater is replenished through rain and snowmelt
Can be contaminated through landfills, septic tank leaks, hazardous waste dumping, leaching underground gas tanks, and overuse of pesticides and fertilizers
Describe a vulnerability assessment. Give an example of when a vulnerability assessment would be used.
A vulnerability assessment is an assessment of a water source based on the surrounding environment
Ex. A farming community would have concerns about animal waste and pesticides being in their water source
Ex. An urban community would be concerned about the nearby manufacturing plants and storm water runoff
What is a point source? Give an example.
Pollution comes from a single point of origin
Ex. A refinery pumping CO2 into the air
Ex. A pipe draining hazardous waster into a water source
What is a non-point source? Give an example
Pollution is diffused; facilitated by rainfall and snowmelt
Ex. Pesticides from agricultural runoff leaching into the ground or flowing into a water source
Ex. Pollution from urban surfaces creating runoff into water systems
Describe how Nitrate contaminates water sources. How are Nitrate and Chloride similar?
Agricultural practices or sewages
They do not absorb readily onto soil materials and can be transported over long distances
How does salt (Na) get into water sources
Salt in groundwater may be the result of the upwelling of sea water in coastal areas or road deicing
What two inorganic chemicals occur naturally in areas containing sediments derived from igneous rocks?
Flouride
Inorganic arsenic - inorganic carcinogens (skin and internal cancers)
Chlorine-containing man-made organic compounds can remain in groundwater for many years. Why is this a concern?
Most cause severe health problems and have been linked to birth defects and cancer
Contact with high concentrations of toxic metal is most likely to occur where? Name some toxic metals.
In a workplace setting
Mining activities
Cadmium, copper, arsenic, lead
What controls the transport of metals in water?
The transport of metals in water is controlled by their solubility
The solubility of metals is dependent on pH
and the pH of water can be affected by acid drainage from mining activities
Dissolved metals can be absorbed on large organic molecules in water and be transported by them
Describe the Flint water crisis
To save money, the government changed the town’s water source from Lake Huron to the Flint River. The highly corrosive water interacted with the iron and lead pipes, those chemicals entered tap water.
Describe microorganism pathogens. Name the three waterborne pathogens focused on in the water field.
Pathogens are capable of causing disease
Can cause acute and chronic health effects
DO NOT exhibit a cumulative effect
Bacteria, Protozoan parasites, and Enteric viruses
What are the diameters for viruses, bacteria, and helminths?
Viruses in nm = 10^-9 m
Bacteria in um = 10^-6 m
Helminths in mm = 10^-3 m
How are bacteria classified?
Shape and how they respond to the Gram stain (positive or negative) which distinguished chemical and physical properties of the cell wall
Campylobacter spp.
BACTERIA
Most commonly diagnosed cause of gastroenteritis in the U.S. -1 mill illnesses each year
Commonly linked to undercooked poultry but can also be through contaminated water
Pseudomonas spp.
BACTERIA
Can grow in unusual environments
soap residue, pipes, tubing
associated with waterborne outbreaks linked to hot tubs
Escherichia coli (E. Coli)
BACTERIA
Causative agent in food and waterborne outbreaks
Associated with undercooked ground beef
Legionella spp.
BACTERIA
Legionnaire’s disease (lung infection)
Pontiac fever (mild flu)
inhalation of contaminated water droplets
What bacterial pathogen causes Cholera?
Vibrio Spp.
What is indicator bacteria? When could examining this be useful?
Indicator bacteria are not pathogens but can indicate contamination of water
Ex. During Harvey people were concerned about quality of flood water - can test for vibrio in water because only a specific strain causes cholera
Enteric Viruses
Waterborne pathogens
size and shape are determined by amount of nucleic acid and proteins they contain
Rotavirus
ENTERIC VIRUS
“Day care diarrhea”
attacks children under the age of 5
Norovirus
ENTERIC VIRUS
“Winter vomiting disease”
has caused outbreaks on cruise ships
Hep A and Hep E
ENTERIC VIRUS
cause diarrhea
Hep A - foodborne; contaminated water used in food prep
Hep E - same but has a high mortality rate among pregnant women (prevalent in Asia, Africa, India, and Mexico)
Adenovirus
ENTERIC VIRUS
commonly associated with recreational waterborne outbreak
can cause a range of health outcomes including gastroenteritis, eye and ear infections, and obesity
water quality issue at 2016 summer Olympics in Rio
Coxsackievirus
ENTERIC VIRUS
More adverse health outcomes than any other waterborne agent
Gastroenteritis, heart disease, and diabetes
Describe Protozoan Parasites
Microscopic one-celled organisms that can be free-living or parasitic in nature
Environmental stage that is highly resistant to water treatment, making it a strategic focus of water utilities
Giardia spp.
PROTOZOAN PARASITE
#1 identifiable waterborne agent
can survive outside the body over a long period of time in a cyst stage protected by an outer shell
Resistant to chlorine disinfection
Cryptosporidium spp.
PROTOZOAN PARASITE
Environmental stage called oocysts
highly resistant to chlorine disinfection
associated with the largest documented waterborne outbreak in the U.S.
What radioactive substances can groundwater contain?
Radons (radioactive gas)
What happened on September 25th, 2015?
Members of the United Nations adopted a set of goals aimed to end poverty and protect planet earth
Each goal set to meet targets by 2030
Define the 2030 agenda for sustainable development
Comprised of 17 sustainable development goals (SDG) targeting 169 environmental, social, and economical factors
Define SDG 6
Clean water and sanitation for all
Why is the goal of clean water and sanitation for all challenging on a global scale?
Many countries do not have the financial means to provide quality drinking water or establish and maintain sanitation infrastructure for the people who live there
It is estimated that 1/3 of Americans lack access to quality drinking water. What are some possible reasons for this?
- As the population continues to grow, water becomes a more limited resource
- Improper water treatment of the breakdown of water treatment at a point in time
- Limited financial resources or poor decision-making (i.e. trying to cut corners and save money by changing the water source)
Define basin sanitation.
Having access to facilities for the safe disposal of human waste as well as having the ability to maintain hygienic conditions, through services such as garbage collection, industrial/hazardous waste management, and wastewater treatment and disposal
Define water stress.
Water stress conditions are when a country’s annual supply of renewable fresh water is between 1000 and 1700 m3/ per person
Can expect temporary water shortages in these conditions
Define water scarcity.
A country faces water scarcity when its annual supply of renewable fresh water is less than 1000 m3 / person
Can expect to experience chronic and widespread water shortages in these conditions
What are the risks of people using one water source for multiple purposes (i.e. washing clothes, drinking, cooking, bathing) ?
The likelihood of health risks associated with exposure to pathogens and chemicals are increased
How are women disproportionately impacted by water stress and water scarcity?
- Women can suffer more sexual violence when there is a lack of privacy in sanitation (bathroom, bathing, etc.)
- Women spend a lot of time collecting water (30 minutes round trip in sub saharan Africa, 1 hour in yemen and somalia)
Both of these impact women and girl’s ability to recieve an education and spend time with family
Describe the public health issue regarding the Rio Olympics.
A risk assessment water done on the water being used in the 2016 Rio Summer Olympics and found that the water contained enteric viruses including Adenovirus on levels similar to sewage. After assessment, protection was suggestion to athletes for what they could do to protect themselves before and after being in the water.
Name some chemical hazards
Lead, mercury, sulfuric acid, asbestos, benzene, arsenic
How many people die a year from unsafe drinking water and inadequate sanitation?
Over 5 million
Define a waterborne outbreak
A waterborne outbreak occurs when at least two people have similar illnesses after ingesting water from the same source and epidemiology indicates water as the source of illness
How would surveillance of waterborne disease impact the understanding of waterborne outbreaks?
Surveillance would help us understand contributing factors to waterborne diseases and would help in the development of mitigation strategies. It would employ a preventative course of action rather that reactionary.
What system did the CDC initiate in 1971? What did the system turn into as of 2009?
In 1971, the CDC initiated the Wasterborne Disease and Outbreak Surveillance System. In 2009, this transition into the Electronic National Outbreak Reporting System where data was collected inclduing factors related to outbreaks (i.e. water system sizes, causative pathogens, disease burden)
Do people in the U.S. get sick from water that meets EPA guidelines?
Yes, experts estimate nearly 20 million illnesses occur each year in the US from drinking water that meets US EPA guidelines
Are immunocompromised populations disproportionately impacted by waterborne hazards?
Yes
Elderly, children, pregnant women, cancer patients, HIV patients
Now called “normal life stages” because most people will be immunocompromised at some point in their life
Why do waterborne illnesses occur despite the advancement in water treatment technology? Name 4.
- Current protocols in municipal water treatement are effective at eliminating pathogens, but can be inadequate, interrupted, or intermitent treatment leading to waterborne disease outbreaks
- Contamination is not evenly distributed (number of pathogens, age of distibution system, quality of delivered water, climate related incidents)
- Private water supplies are not regulated by the US gov and are generally not treated or monitored
- Increasing number of immunocompromised consumers
Define a waterborne disease
A disease the occurs due to the ingestion of contaminated water
Define water-privation disease
A disease associated with illness that occurs due to the lack of water for hygiene purposes or consequences due to limited water
Define water-based disease
A disease associated with agents that require water as part of their life cyclce
Define water-dispersed disease
A disease contracted through inhalation of contaminated water (ex. legionella)
Define water-related disease
Mosquito borne illnesses since mosquitos thrive in standing water
Is secondary transmission of waterborne disease prevalent?
Yes, especially in recreational waters and water used for multiple purposes. Person-to-person transmission magnifies impact of microogranisms.
What is the etiology for most outbreaks? For most illnesses?
Based on a 2011-12 study, bacteria causes most outbreaks and enteric viruses cause the most cases of illness. Additionally, surface water had the most outbreaks and groundwater had the most cases of illness - this makes sense because bacteria is usually found in surface water while enteric viruses are often found in groundwater
What are the current prevention stragtegies for preventing waterborne disease (3)?
- Wash you hands
- Know your watershed
- Use only treated water
What was the largest waterborne outbreak in the US? Explain what, where, and how it happened.
Milwaukee 1993
Government was notified of an outbreak by anti-diarrheals flying off shelves and pharmacies being sold out
Stool samples returned negative for enteric viruses or bacteria
One scientist decided to test for protozoan parasties and foun cryptosporidium
There were $9.6 M in damages
403,000 cases of diarrhea
4,000 cases hospitalized and 100 deaths
The outbreak was caused by high rainfall that caused local flooding leading to a small outbreak of cryptosporidium. Oocysts increased in the sewage system and effluent (sewage discharge) flowed into Lake Michigan, their source of drinking water. Filter failures at the treatment plant did not take out cryptosporidium and led to intake into drinking water.
What are the current waterborne disease control measures (4)?
- Surveillance
- Know your watershed
- Water exposure
- Prevention
What is risk?
The probability of something to cause harm (i.e. infection or disease)
T or F: All environmental sources pose a risk, there is no such thing as zero risk
True
What is the purpose of a risk assessment? From a water utility perspective?
To assess the possibilities, probabilities, and outcomes/impacts of a hazard. Also used as a translation tool for environmental data to public health impact. Risk assessments can inform water treatment that should be administered to keep pathogens as low as possible and can develop standards and policies.
What are the three steps of risk analysis?
- Risk Assessment
- Risk Management
- Risk Communication
What are the four steps of risk assessment?
- Hazard Identification
- Dose-Response Assessment
- Exposure Assessment
- Risk Characterization
Define Hazard Identification.
Describes completely the range of human illness possibly created by a hazard and considers varying population it may effect.
Define dose-response. What are some challenges?
A dose-response assessment defines the relationship between dose of a hazard and the effect on an organism. Challenges include extrapolating animal data to human data and evaluating threshold vs nonthreshold hazards
Describe the dose-response assessment for chemicals
ADI = NOAEL or LOAEL / UF
Where ADI is acceptable daily intake
NOAEL or LOAEL is no /lowest observed adverse effect level
UF is uncertainty factor
What are the two models best fit for dose-response assessment of waterborne microogranisms? What are the equations?
- Exponential model: Pi = 1 - exp(-rN)
- Beta Poisson Model: Pi = 1 - (1 + N/beta) ^alpha
where r is number of microogranisms that survive and are capable of infection
N is the number of organisms ingested or inhaled
alpha and beta are parameters of host-microbe interaction
Equation for risk of illness
Pi x morbidity ratio
Equation for risk of death
Pi x morbidity ratio x case/fatality ratio
Equation for annual risk of infection
Pyear = 1 - (1 - Pi)^365
note that 365 can be changed to any number of days of exposure per year
Define exposure assessment
Exposure assessments define amount of water consumed or contacted, concentration of hazard, and survivability and resistance of hazard to inactivation
Exposure assessment for chemicals
Concentration x Time
Exposure assessment for microorganisms
Concentration / Volume
Explain how exposure-related variables relate to risk.
Most exposure-related variables such as water intake and number of pathogens increases with risk. However, immunity does not follow this - as immunity increases risk decreases; as immunity decreases risk increases
Define Risk characterization
Risk characterization interprets information learned through the first three steps
Lists uncertainties and assumptions
Estimated human health effects resulting from exposure - this can be both qualititative and quantitative analysis
What are some of the applications of risk assessment?
- Identifies information gaps
- Evaluates treatment efficiency
- Provides comparison for risk-risk trade offs
- Identifies prevalent hazards
- Evaluates different water sources and populations
- Identifies potential indicator microorganisms
- Identifies resistant microorganisms
What is considered acceptable risk for microorganisms in drinking water?
One infection per 10,000 individuals (1 / 10,000)
