QMRA Exercises

1
QMRA Exercises
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QMRA for Beach Exposure

• Given)
• An effluent from a municipal wastewater plant,
  which has a secondary treatment system, is
  released into a near beach in a Lake and it is
  assumed that the initial dilution the is 1/100.
• A person at a beach may ingest 0.1 L of the beach
  water during swimming
• Assume parameters based on available data in the
  following table.

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QMRA for Beach Exposure
Raw Sewage (per L) 2ndary Treatment Removal (log10) Die-off in Fresh Water (log10/day) Dose-Response Equation
Microorganism Raw Sewage (per L) 2ndary Treatment Removal (log10) Die-off in Fresh Water (log10/day) Dose-Response Equation
Fecal coliforms 106 - 108 2.06 1.2 - 0.21_at_10-20ºC n/a
Fecal streptococci 105 - 107 n/a n/a n/a
Clostridium perfringens 104 - 106 n/a n/a n/a
Enteric viruses 104 - 105 1.7 0.59 - 0.17_at_4-20ºC n/a
Poliovirus I (minor) n/a n/a n/a 1-EXP(-0.0091dose)
Rotavirus n/a n/a n/a 1-(1(dose/6.17)(2(1/0.2531)-1))-0.2531
Hepatitis A virus n/a n/a n/a 1-EXP(-0.55dose)
Adenovirus n/a n/a n/a 1-EXP(-0.42dose)
Echovirus 12 n/a n/a n/a 1-EXP(-0.012771dose)
Campylobacter jejuni 103 - 106 n/a n/a 1-(1(dose/896)(2(1/0.145)-1))-0.145
Salmonella 103 - 105 n/a 1.2 - 0.12_at_10-20ºC 1-(1(dose/23600)(2(1/0.3126)-1))-0.3126
Shigella 10 - 104 n/a n/a 1-(1(dose/1124)(2(1/0.21)-1))-0.21
E.coli (pathogenic) n/a n/a 0.27 - 0.067_at_15ºC 1-(1(dose/8.6107)(2(1/0.178)-1))-0.178
Vibrio Cholera n/a n/a n/a 1-(1(dose/243)(2(1/0.25)-1))-0.25
Cryptosporidium parvum 103 - 106 1.14 0.024 - 0.006_at_15ºC 1-EXP(-0.0042dose)
Giardia lamblia 103 - 105 1.19 0.29 - 0.13_at_12-20ºC 1-EXP(-0.02dose)
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QMRA for Beach Exposure

• Find)
• Choose pathogens from a list of viruses,
  bacteria, and protozoan in the table and
  calculate point estimate risks for a swimmer at
  the beach.
• Does the treatment system remove enough pathogens
  to protect swimmers health? EPA acceptable risk
  for recreational fresh water is 0.008 (marine is
  0.019). How much removal at the treatment plant
  would be recommended?
• A sewage spill has occurred resulting in
  releasing untreated wastewater introduced in to
  the beach. How long a beach should close?

5
QMRA for Anthrax Exposure

• Given)
• Suspicious white powders were delivered to an
  office. All employee were evacuated in a short
  time but several employees in a small room were
  hospitalized.
• Assuming that the inhalation rates for adult
  males, adult females, and children are 0.0106,
  0.0078, and 0.0060 m3/min, respectively.
• The white powder was identified as Bacillus
  anthracis. The fatal risk for inhalation of B.
  anthracis base on animal tests (guinea pigs,
  rabbits, and rhesus monkey) was estimate by
• Risk (fatal) 1-(1(dose/62817)(2(1/0.97
  4)-1))-0.974

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QMRA for Anthrax Exposure

• Find)
• If the concentration is the same, who would be at
  most risk, adult males, females, or children?
• What concentrations could have been at the safe
  level for 15 min exposure? Assuming that an air
  exchange and particle settling and re-suspending
  were negligible. Assuming that the acceptable
  risk is 10-4.
• The room has been decontaminated. Does the room
  have to be completely spore free? If not, how
  many numbers of spores should not be available
  for further exposures in the room?