Exposure assessment new

From QMRAwiki
Jump to: navigation, search

Introduction

Exposure at the simplest level is the dose of the pathogen that an individual ingests (eg. number of noroviruses), inhales (eg. numbers of bacteria cells of Legionella), or comes in contact with (eg. numbers of skin bacterial pathogens such as Staphylococcus). This number feeds into the dose-response models to predict the probability of infection. However exposure assessment is very complex and involves a combination of addressing the methods used to measure the microbes and the concentrations in the water or air for example, as well as the timing of the exposure. In most cases exposure can be viewed as a pathway from the source of the pathogen (eg shedding of pathogens by infected individuals, or concentrations in sewage) to the actual exposure (swimming at the beach). This also involves understanding the transport and survival of the microbe.


Exposure is often venue or media specific. Federal agencies such as EPA and FDA have developed long term programs to collect and accrue large amounts of data on populations exposures to drinking water and types of food often separated by age. EPA Exposure Factors Handbook


This section will begin to collect and present the parameters which are associated with exposures for water and fomites and will include pathogen specific parameters.

  • Pathogen excretion from infected individuals or populations
  • Pathogen occurrence and concentrations in various sources
  • Pathogen inactivation over time on various surfaces, in water
  • Amount of air inhaled, water ingested


1. Pathogen Specific

1.1. Excretion

Table 1: Fecal Output for Different Populations
Population Age Number of Subjects Mean Standard Deviation References
Healthy people
Healthy Nigerian Children 6 months to 5 years 410 109.3 mL/day 54.07 Akinbami et al. 1995
Healthy Nigerian Adult 23-28 years 37 143.3 g/day 48.5 Ogunbiyi 1978
Healthy British Children and Adult 11-56 years 17 153 g/day 79 Davies et al. 1986
Healthy American Adult Adult 115 123.6 g/day 40.2 Rendtorff et al. 1967
Ill people
Indian Children with diarrheaa 3 to 24 months 70 126 g/kilogram of body weight/hour
during initial 24 hours and rehydration period
33.6 Dutta et al. 2000
Tunisian Adult with acute diarrheab over 18 years 70 499 g/day 284 Hamza et al. 1999
American Adult infected with Enteropathogenic Escherichia coli 18-40 years 11 406 g/day 300 Donnenberg 1993

a In this study, a high isolation rate of different enteropathogens, e.g. Shigella flexneri, Shigella boydii,Salmonella typhimurium, Enteroagrregative E. coli, Enteropathogenic E. coli, Aeromonus sp. and rotavirus was observed.
b Shigella, E. coli, Proteus, Pseudomonas aeruginosa were identified from the subjects.

Akinbami, F., Erinoso, O. and Akinwolere, O. (1995) Defaecation pattern and intestinal transit in nigerian children. African Journal of Medicine and Medical Sciences 24, 337-341. Abstract

Dutta, P., Dutta, S., Manna, B., Chatterjee, M. and De, A. (2000) Hypo-osmolar oral rehydration salts solution in dehydrating persistent diarrhoea in children: Double-blind, randomized, controlled clinical trial. Acta Paediatrica 89, 411-416. Full text

Hamza, H., Ben Khalifa, H., Baumer, P., Berard, H. and Lecomte, J.M. (1999) Racecadotril versus placebo in the treatment of acute diarrhoea in adults. Alimentary Pharmacology and Therapeutics 13, 15-19. Full text

Ogunbiyi, T.A. (1978) Whole-gut transit rates and wet stool weight in an urban Nigerian population. World Journal of Surgery 2(3), 387-392. [1]

Table 2. Concentration of microbes in stools of an infected person and incidence of microbes in the United States
Organism Concentration in stool per gram Reference Incidence(%) Notes Reference
Giardia 1-5*106 Jakubowski, 1984 3.8 All age groups Howell and Waldron, 1978
18-26 Children in day care centers Sealy and Shuman, 1983
29-54 Developed countries Black et al, 1977
Cryptosporidium 106-107 Robertson, 1994 0.6-20 Children in day care centers Soave and Weikel, 1990
27-50 Ungar, 1990
Hepatitis A 108 Coulepis, 1980 0.0097 Reported cases of clinical illness MMWR, 1988
8.2 Occurrence of virus in stools of healthy person DeFilippes et al, 1987
Rotavirus 1010-1012 Flewett, 1982 10.4 Annual rates of clinical infection Monto et al, 1983
29 Children under 2 years of age Champsaur et al, 1984
Poliovirus 103-106.5 Melnick and Rennick, 1980
Coxsackie and echo virus 102-105.5(max. 107.2) Melnick and Rennick, 1980
Fecal coliform 107-109 Feachem et al, 1983
Enterovirus 10 Occurrence in fecally soiled diapers Peterson, 1972; 1974
30-40 During the summer months Fox and Hall, 1980

Black R.E., Dykes A.C, Sinclair S.A., and Wells J.G. (1977) Giardiasis in day-care centers: evidence of person to person transmission. Pediatrics. 60: 193-197. Full text

Champsaur H. Questiaux E., Prevot J. et al. (1984) Rotavirus carriage, asymptomatic infection, and disease in the first years of life. I. Virus shedding. J Infect Dis. 149: 667-674. Full text

Coulepis A.G., Locarnini S.A., Westway E.G., Tannock G.A., Gust I.D. Biophysical and biochemical characterization of hepatitis A virus. J Infect Dis 141: 151-156. Summary

Feachem R.G., Bradley D.J., Garelick H. , Mara D.D.. 1983. Sanitation and disease (John Wiley and Sons, Inc. NY)

Flewett T.H.. Clinical features of rotavirus infections, in virus infections of the gastrointestinal tract, edited by D.A.J. Tyrell, A.Z. Kapikian (Marcel Dekker Inc. NY, 1982). 125-146.

Fox J.P., Hall, C.E. Viruses in families(PSG Publishing Company, Inc. Littleton, MA. 1980).

Howell R.T.k, Waldron B.S.. Intestinal parasites in Arkansas. J Arkansas Med Soc. 75: 212-214.

Jakubowski W. Detection of Giardia cysts in drinking water: State-of-the-art, in Giardia and Giardiasis, Biology, Pathogenesis and Epidemiology, (Plenum Press, NY, 1984). 263-285.

Melnick J.L. (1957) Special publication of the New York Acad of Science. 5: 365-381.

Melnick J.L., Rennick V. (1980) Infectivity of enterovirus as found in human stools. J Med Virology. 5: 205-220. Full text

Monto A.S., Koopman J.S. Longini I.M., Isaacson R.E.. (1983) The Tecumseh study XII. Enteric agents in the community, 1976-1981. J Infect Dis. 148: 284-291. Full text

MMWR. (1988) Morbidity and mortality weekly, summary-cases of specific notifiable diseases, United States. MMWR. 36: 840

Peterson M.L. (1972) The ocurrence and survival of viruses in municipal solid waste. Dissertation abstracts. 33/3, 2232-B-2233-B. Ann Arbor, MI.

Peterson M.L. (1974) Soiled disposable diapers: A potential source of viruses. Amer J Public Hlth. 64: 912-914. Full text

Robertson L.J., Smith H.V., Paton C.A.. Occurrence of Giardia and Cryptospordidium oocysts in sewage effluent in six sewage plants in Scotland and the prevalence of cryptosporidiosis and giardiasis diagnosed in the communities served by those plants, in Protozoan Parasites in Water.. 45-49

Sealy D.P, Shuman S.H. (1983) Endemic giardiasis and day care. Pediatrics. 72: 154-158. Full text

Soave R., Weikel C.S.. Cryptosporidum and other protozoa including Isospora, Sacryocysts, Blantidium coli and Blastocysts, in Principles and Practice of Infectious Disease. (Churchill Livingstone Inc., NY, 1990) 2122-2130

Ungar B.L. Cryptosporidiosis in humans (homo sapiens), in Cryptosporidiosis in man and animals. (CRC Press, Boca Raton, FL, 1990). 59-82

1.2. Occurrence

1.2.1. Water

Table 3. Pathogens in Groundwater
Pathogen Location Presence/Absence Concentration a Note References
Total Cultural Enteric Viruses
(BGM b)
Missoula, MT
Eight Wells from Unconfined Aquifer
n = 7
 % positive = 0
Min: < 0.67
Max: < 4.05
Avg: < 1.74
Std: < 1.43
Unit: MPN/1000L
Water samples from wells beneath and adjacent to the
drainfield of the septic tanks were collected.
Please see the virus data in septic tanks in Table Y.
DeBorde et al, 1998
Total Cultural Enteric Viruses
(BGM b)
Nottingham and Birmingham, UK
Two Sandstone Aquifers
n = 107
 % positive = 10
Detection limit: 1000
Min: 5000
Max: 10,000
Avg: 1382
Std: 1670
Unit: PFU/1000L
Only two quantifiable samples were found. Powell et al, 2003
Six virus groups c
(qRT-PCR)
Madison, WI
Six municipal water-supply wells from sandstone aquifer
n = 147
 % positive = 47
Max: 6.27
Avg: 0.65
Unit: Gene Copies/L
Virus levels in Lake Mendota and sewage influent were also analyzed. Bradbury et al, 2010
Five virus groups d
(RT-PCR)
La Crosse, WI
Six drinking-water supply wells
n = 48
 % positive = 50
Occurrence of virus in river samples was also analyzed. Borchardt et al, 2004
Five virus groups d
(RT-PCR)
Madison, WI
Three wells from confined bedrock aquifer
n = 30
 % positive = 23
One well is located in a suburban area from which no positive sample was found.
The other two wells located in highly urbanized areas from which 7 positives were found.
Borchardt et al, 2007
Five virus groups d
(RT-PCR)
Wisconsin
Fifty private household wells
n = 194
 % positive = 2.6
All samples were negative for culturable viruses. Borchardt et al, 2003
Four virus groups e
(RT-PCR)
United States
n = 448
 % positive = 31.5
Groundwater were collected from 448 sites in 35 states in US.
 % positive for each specific virus was also reported.
Abbaszadegan et al, 2003
Total Cultural Enteric Viruses
(BGM b)
United States
n = 442
 % positive = 4.8
Min: 0.9
Max: 18.6
Unit: MPN/1000L
Total Cultural Enteric Viruses
(MA-104)
Quebec, Canada
Twelve municipalities
n = 113
 % positive = 8
Min: 3
Max: 589
Unit: MPN/1000L
Municipalities were divided into 3 groups: group A with no known microbial contamination;
group B with groundwater sporadically contaminated by total coliform;
group C were historic and continuous contaminated by total coliforms and fecal coliforms.
No virus was found in A. Virus was found in one sample in B and 8 samples in C.
Locas et al, 2007
Total Cultural Enteric Viruses
(BGM b)
Quebec, Ontario, and Alberta of Canada
25 sites
n = 130
 % positive = 0.8
10 MPN/1000L One sample was positive in Quebec site.
None was positive in other two sites.
Locas et al, 2008
Total Cultural Enteric Viruses
(BGM b)
Long Island
Three wells
n = 30
 % positive = 20
Min: 343
Max: 2800
Avg: 1030
Std: 898
Unit: PFU/1000L
The recovery of viruses from groundwater established the ability of virus particles to penetrate these shallower basins (18 to 34 feet) from wastewater treatment plant. Vaughn et al, 1978

a: All averages included negative samples reported at detection limit
b: Cell culture line
c: Enteroviruses, adenoviruses, rotavirus, hepatitis A virus (HAV), and norovirus genogroups I and II
d: Enteroviruses, rotavirus, hepatitis A virus, and norovirus genogroups I and II
e: Enteroviruses, rotavirus, hepatitis A virus, and norwalk virus

1.2.2. Air

1.2.3. Fomite

1.2.4. Soil

1.3. Survival

1.3.1. Water

Table 4. Decay rates of viruses in groundwater
Viruses Location Temperature °C Decay rate -[(log10PFU)/day] Viruses Location Temperature °C Decay rate -[(log10PFU)/day] Viruses Location Temperature °C Decay rate -[(log10PFU)/day]
Echovirus 1 Wisconsin 4 ND a MS-2 bacteriophage Wisconsin 4 0.020 Poliovirus 1 Wisconsin 4 ND
12 0.066 12 0.093 12 0.060
23 ND 23 0.244 23 ND
Arizona 4 ND Arizona 4 0.064 Arizona 4 ND
12 ND 12 0.162 12 ND
23 0.188 23 0.578 23 0.357
North Carolina 4 ND North Carolina 4 0.013 North Carolina 4 ND
12 0.180 12 0.063 12 0.126
23 ND 23 0.225 23 ND
University of Arizona 4 ND University of Arizona 4 0.025 University of Arizona 4 ND
12 ND 12 0.040 12 ND
23 0.628 23 0.325 23 0.676
New York 12 0.053 New York 12 0.036 New York 12 0.043
Texas 13 0.109 Texas 13 0.096 Texas 13 0.087
California 17 0.091 California 17 0.075 California 17 0.081
18 0.151 18 0.082 18 0.185

a: ND, Not done
(Yates et al, 1985)

1.3.2. Air

1.3.3. Fomite

Fomites are any nonliving object such as books, desks, floors, clothing, paper, and phones that humans interact with and touch. These fomites can be contaminated with pathogens, which survive and may accumulate on the surface and these pathogens can be spread microbes from person to fomite to person. Fomites are experienced and encountered everyday and are more frequently touched (eg per day) than other exposure routes, such as swimming, food (three meals) or drinking water (eg. 4 glasses of water). When developing a QMRA around fomite exposures, there are a number of key pieces of information and data that need to be addressed. First how does the pathogen find its way to the fomite and what concentrations may be laid down on the fomite, second how well does the pathogen survival on fomites and finally how is the pathogen transferred from the fomite to the exposure individual. CAMRA investigators have begun to address some of these data needs. Survival of pathogens on fomites are summarized as decay rates (survival). Decay rates are given as first order loss rates since they are defined simply as a loss of pathogen viability over time, this also works well for stochastic modeling (i.e. Markov chain models).

Recovery efficiency is an area which is not well studied, and requires data on hand to fomite interactions and the % of microorganisms transferred to the hand or fingers and then the transfer of the microorganisms from the hand to the face, eye, mouth, and nose.

Recovery efficiency is made up of recovery, survival and percent that is transferred. The testing apparatus and method (i.e. swab or wipe with a broth) is used to evaluate the concentrations on the fomite and can be described as recovery. Recovery efficiencies from fomites to hands or fingers are specifically estimated based on the hosts touching contaminated fomites. In either case these efficiencies are unitless parameters, as they describe the percentage of pathogens contaminating a fomite, that are recovered from the fingers or hands.

The associated experiments, usually evaluate different fomite materials. The fomites are typically coated or otherwise inoculated with a known amount of pathogens and/or pathogen surrogates, then recovery can be addressed this can be performed through the use of swabs; transfer is evaluated via the touching of the contaminated fomite with human fingers or human finger surrogates. Table 1 shows the recovery efficiencies, reported as percent (%) of inoculated organisms recovered from the fomite via fingers.


  • Recovery Efficiency from Fomites to Hand
Table 5. Recovery Efficiencies from both porous and non-Porous Fomites
Porous and Non-Porous Fomites
Pathogen Relative Humidity Acrylic Ceramic Tile Cotton Glass Laminate Paper Money Polyester Stainless Steel
Bacillus thuringiensis
17% - 30%
  Min = 45.8
Max = 74.8
μ = 57.0
σ = 12
N = 6
Min = 0.09
Max = 0.31
μ = 0.15
σ = 0.08
N = 6
Min = 0.52
Max = 0.78
μ = 0.63
σ = 0.11
N = 6
Min = 0.32
Max = 0.91
μ = 0.54
σ = 0.25
N = 6
Min = 0.05
Max = 0.2
μ = 0.13
σ = 0.05
N = 6
Min = 0.02
Max = 0.17
μ = 0.06
σ = 0.06
N = 6
Min = 0.15
Max = 1.7
μ = 0.63
σ = 0.57
N = 6
Min = 0.39
Max = 1.0
μ = 0.52
σ = 0.24
N = 6
40% - 65%
  Min = 48.8
Max = 84.9
μ = 65.6
σ = 15.9
N = 6
Min = 1.3
Max = 76.4
μ = 21.2
σ = 28.2
N = 6
Min = 0.85
Max = 10
μ = 3.5
σ = 3.5
N = 6
Min = 4.3
Max = 65.9
μ = 33.8
σ = 24.0
N = 6
Min = 33.8
Max = 79.0
μ = 53.5
σ = 19.6
N = 6
Min = 0.01
Max = 0.07
μ = 0.04
σ = 0.02
N = 6
Min = 0.61
Max = 1.63
μ = 1.2
σ = 0.38
N = 5
Min = 47.5
Max = 71.4
μ = 57.0
σ = 9.7
N = 6
E. coli O15597
17% - 30%
  Min = 1.1
Max = 93.5
μ = 49.5
σ = 44.5
N = 6
Min = 0.1
Max = 5.2
μ = 12.5
σ = 2.19
N = 6
Min = 3.4
Max = 50
μ = 16.8
σ = 16.8
N = 6
Min = 0.7
Max = 15.1
μ = 5.4
σ = 5.6
N = 6
Min = 5.2
Max = 66.5
μ = 21.7
σ = 23.9
N = 6
Min = 0.017
Max = 0.12
μ = 0.046
σ = 0.04
N = 6
Min = 0.07
Max = 0.87
μ = 0.37
σ = 0.28
N = 6
Min = 1.5
Max = 100
μ = 19.6
σ = 39.5
N = 6
40% - 65%
  Min = 29
Max = 100
μ = 66.1
σ = 31.4
N = 6
Min = 3.28
Max = 100
μ = 71.9
σ = 37.5
N = 6
Min = 10
Max = 50
μ = 27.7
σ = 15.1
N = 6
Min = 0.25
Max = 100
μ = 58.5
σ = 38.2
N = 6
Min = 1.9
Max = 46.4
μ = 14.8
σ = 17.2
N = 6
Min = 0.065
Max = 0.65
μ = 0.14
σ = 0.25
N = 6
Min = 0.06
Max = 2.2
μ = 0.69
σ = 0.78
N = 6
Min = 48.9
Max = 98.9
μ = 68.6
σ = 21.4
N = 6
MS-2 bacteriophage
17% - 30%
  Min = 3.0
Max = 40.6
μ = 21.7
σ = 15
N = 6
Min = 3.78
Max = 15
μ = 7.10
σ = 4.03
N = 6
Min = 0.01
Max = 0.05
μ = 0.03
σ = 0.02
N = 6
Min = 2.90
Max = 40.5
μ = 19.3
σ = 13.2
N = 6
Min = 1
Max = 10
μ = 5.35
σ = 3.56
N = 6
Min = 0.13
Max = 0.95
μ = 0.42
σ = 0.38
N = 6
Min = 0.05
Max = 0.70
μ = 0.26
σ = 0.25
N = 5
Min = 4
Max = 40
μ = 13.7
σ = 13.5
N = 6
40% - 65%
  Min = 35.2
Max = 100
μ = 67.9
σ = 27.2
N = 6
Min = 16.8
Max = 74.7
μ = 33.4
σ = 22.5
N = 6
Min = 0.04
Max = 0.64
μ = 0.26
σ = 0.26
N = 6
Min = 37.4
Max = 96.9
μ = 67.3
σ = 25
N = 6
Min = 2.79
Max = 95.7
μ = 53.3
σ = 33.4
N = 6
Min = 0.09
Max = 1.45
μ = 0.66
σ = 0.53
N = 6
Min = 1.19
Max = 3.20
μ = 2.26
σ = 0.081
N = 5
Min = 19.5
Max = 62.4
μ = 37.4
σ = 16
N = 6
Staphylococcus aureus
17% - 30%
  Min = 0.36
Max = 3.1
μ = 1.5
σ = 1.1
N = 6
Min = 0.80
Max = 6.7
μ = 2.7
σ = 2.3
N = 6
Min = 0.44
Max = 1.9
μ = 0.96
σ = 0.60
N = 6
Min = 0.6
Max = 85.4
μ = 20.3
σ = 33.4
N = 6
Min = 1.3
Max = 7.4
μ = 4.2
σ = 2.4
N = 6
Min = 0.09
Max = 0.44
μ = 0.23
σ = 0.14
N = 6
Min = 0.04
Max = 0.13
μ = 0.37
σ = 0.48
N = 6
Min = 1.13
Max = 11.9
μ = 3.9
σ = 3.9
N = 6
40% - 65%
  Min = 24.4
Max = 67.3
μ = 47.2
σ = 17.9
N = 6
Min = 27.7
Max = 77.6
μ = 54.7
σ = 18.8
N = 6
Min = 0.07
Max = 1.32
μ = 0.50
σ = 0.46
N = 6
Min = 25.7
Max = 65.5
μ = 45.5
σ = 15.5
N = 6
Min = 30.9
Max = 89.9
μ = 61.9
σ = 24.7
N = 6
Min = 0.06
Max = 0.32
μ = 0.18
σ = 0.10
N = 6
Min = 0.07
Max = 15.46
μ = 5.04
σ = 6.86
N = 6
Min = 16.6
Max = 85.5
μ = 48.3
σ = 25.4
N = 6


  • Transfer Efficiencies from Hand-to-Mouth
Table 6. Transfer Efficiencies from Hand-to-Mouth for Humans, Summarized from Rusin et al. (2002)
Microorganisms
Number of Subjects Transfer Efficiency *
Micrococcus luteus
20
0.41
PRD-1 bacteriophage
0.34
Serratia rubidea
0.34
*: Defined as -- CFU on lip/sum(CFU on lip, CFU recovered from transfer finger)

Rusin, P. Maxwell, S., Gerba, C. (2002) Comparitive Surface-to-Hand and Fingertip-to-Mouth Transfer Efficiency of Gram-Positive Bacteria, Gram-Negative Bacteria, and Phage Journal of Applied Microbiology 93 585-592 Full Text via Google Scholar


Survival is typically defined as a ratio of the numbers of remaining cultivatible cells (CFU, PFU, MPN units) which are viable divided by the starting concentration at any given time point with a rate of reduction over time. First order decay rate is based on a set of something subject to decay (such as a microorganism) that decreases in population at a rate proportional to its original population size. First order decay is often described as a k value via log10 reduction/time (in hours or days).

The simple formula or concept is as follows for calculating k

M0 =microbe numbers at time zero, Mt = microbe numbers at time t, T is time t.

K.jpg


For example for a bacteria measured in CFU

K example.jpg


Experimental design for assessing survial varies greatly and are dependent on the date of publication (different techniques available in 1911 as compared to 2011). However the basic experimental plan is to have live pathogens exposed to air, in water, on surfaces and through monitoring and determine the remaining numbers at given time intervals. Thus addressing how much is inactivated in the matrix of interest (e.g air, water etc.). For decay rates on fomites, the chosen fomite(s) is(are) inoculated with a known amount of pathogens and then the survival of these pathogens are monitored again recording how the total number is degrading over time. Recovery is presumed to be constant at time zero as well as over time, and therefore does not impact the calculated rates (this assumption may or may not be correct).


  • Survival of Pathogens on Fomites and Environmental Matrices
Table 7. Survival Rates of Pathogens in Aerosols (Air)
Aerosols
Pathogen Strain or Surrogate Temperature (oC) Relative Humidity (%) Decay Rate (log10/hr) Source
Bacillus anthracis Not Reported Not Reported Not Reported 4.64 (10-7) Stuart et al. (2005)
Francisella tularensis Schu S5 -40 Ambient 0.97 Erlich and Miller (1995)
-29 Ambient 0.25
-7 Ambient 0.37
24 85 0.55
29 85 0.90
35 85 2.08
Live Vaccine Strain 90 Not Reported 0.03 Cox (1971)
Cox and Goldberg (1972)
80 Not Reported 1.20
70 Not Reported 2.09
60 Not Reported 8.00
50 Not Reported 9.59
40 Not Reported 9.39
30 Not Reported 9.20
20 Not Reported 3.97
0 Not Reported 3.95
Live Vaccine Strain
freexe dried in peptone broth
90 Not Reported 6.15 Cox (1971)
Cox and Goldberg (1972)
80 Not Reported 9.20
70 Not Reported 7.83
60 Not Reported 6.71
50 Not Reported 6.09
40 Not Reported 4.18
30 Not Reported 4.00
20 Not Reported 1.31
0 Not Reported 1.20
Yersinia pestis A-1122 26 87 3.49 Won and Ross (1966)
50 2.10
20 2.66
Variola major Vaccinia virus 10.5 - 11.5 20 0.00 Harper (1961)
10.5 - 11.6 50 0.00
10.5 - 11.7 80 0.02
21.0 - 23.0 20 0.03
21.0 - 23.1 50 0.03
21.0 - 23.2 80 0.13
31.0 - 33.5 20 0.03
31.0 - 33.6 50 0.11
Vaccinia virus McLlvaine buffer
1% horse serum
22 20 0.01 Harper (1963)
10 50 0.05
10 80 0.09
Arenaviridae
(Hemorrhagic Fever)
Venezuelan equine
encephalitis virus
9.0 - 9.5 19 0.00 Harper (1961)
48 0.02
86 0.05
21 - 23 19 - 23 0.04
50 0.10
81 - 86 0.12
20.5 - 23.5 19 0.09
48 0.22
81 - 85 0.86
Arenaviridae
(Hemorrhagic Fever)
Lassa virus Josiah strain 24 30 1.12 Stephenson et al. (1984)
55 1.08
80 1.41
32 30 0.68
55 0.60
80 0.55
38 30 0.59
Flaviviridae
(Hemorrhagic Fever)
Japanese encephalitis
virus Peking strain
24 30 0.17 Larsen et al. (1980)
55 0.24
80 0.33
Flaviviridae
(Hemorrhagic Fever)
St. Louis encephalitis
Parton strain
Not Reported 80 0.13 Rabey et al. (1969)
80 0.16
60 0.08
61 0.20
46 0.07
46 0.09
35 0.03
23 0.001
Flaviviridae
(Hemorrhagic Fever)
Marburg virus Not Reported Not Reported 3.00 Belanov et al. (1966)


  • Survival of Pathogens on Various Fomite Materials
Table 8. Survival Rates of Pathogens on Fomites
Pathogen Strain Fomite Material Temperature (oC) Relative Humidity (%) Decay Rate (log10/hr) Source
Francisella tularensis Live Vaccine Strain Metal 25 100 0.13 Wilkinson (1966)
65 0.07
10 0.01
37 100 0.46
80 0.38
65 0.37
55 0.25
Yersinia pestis A1122 Metal 11 30 0.04 Wilkinson (1966)
100 30 0.20
52 30 16.90
52 22 0.69
Stainless Steel 18 - 22 55 0.98 Wilkinson (1966)
Polyurithane 0.21
Glass 1.13
Paper 0.07
Harbin Stainless Steel 18 - 22 55 1.24 Rose et al. (2003)
0.91
Polyurithane 0.85
0.25
Glass 0.06
0.06
Paper 0.07
0.04
Variola major Variola minor Scabs in Envelopes 15 - 30 35 - 98 2.79 (10-3) Wolf et al. (1968)
Vaccinia virus Glass Slides 25 96 6.43 (10-3) Mahl and Sadler (1975)
55 9.95 (10-3)
7 6.41 (10-3)
37 93 5.45 (10-3)
55 6.87(10-3
3 6.25 (10-3)


  • Survival of Pathogens in Water, and Specific Types of Water (i.e. Stormwater)
Table 9: Survival Rate of Pathogens in Water
Pathogen Strain Media Notes Temperature (oC) Decay Rate (log10/hr) Source
Bacillus anthracis Not Reported Freeze Dried in Glass
Bottles
100 0.27 Dearmon et al. (1956, 1962)
90 0.07
80 0.01
Pasteur pH 7 Buffer 70 0.52 Mentville et al. (2005)
80 7.06
9- 69.80
Pasteur Milk 70 0.29
80 3.82
90 60.00
Pasteur pH 4.5 Buffer 70 6.52
80 31.60
90 70.60
Pasteur Orange Juice 70 6.45
80 20.00
90 88.20
Vollum pH 7 Buffer 70 0.26
80 2.01
90 12.20
Vollum Milk 70 0.30
80 2.47
90 8.96
Vollum pH 4.5 Buffer 70 0.60
80 7.50
90 37.50
Vollum Orange Juice 70 0.73
80 7.89
90 30.00
Francisella tularensis Not Reported Tap Water 8 3.9 (10-3) Forsman (2000)
Cell Culture Media 37 1.73 (10-2) Dearmon et al. (1962)
26 1.18 (10-2
15 1.03 (10-4
3 3.02 (10-4
0 4.79 (10-4
Freeze Dried in
Peptone Broth
37 6.16 (10-3
27 1.56 (10-3)
15 2.55 (10-3
3 3.82 (10-5
-18 1.77 (10-5
Vaccinia virus Not Reported Storm Water 4.5 1.40 (10-3) Essbaur et al. (2007)
19 - 23 1.39 (10-2)
Storm water with
Fetal Calf Serum
4.5 1.40 (10-3)
19 - 23 3.00 (10-3)
Storm Water and Soil 4.5 8.00 (10-3)
19 - 23 3.47 (10-2)
Tap Water 9 1.00 (10-3) - 2.80 (10-3) Mandell et al. (2005)
15 4.00 (10-4)
River Water 9 1.00 (10-3) - 3.40 (10-3)
15 1.00 (10-3) - 2.60(10-3)
Seawater 11.5 3.56 (10-3) Balawat et al. (1976)
Phosphate Buffer
Solution
3.13 (10-3)
Flaviviridae
(Hemorrhagic)
Yellow Fever
Virus
0.9% Saline 37 1.40 (102-) Adebayo et al. (1998)
Adenovirus
(Hemorrhagic)
Not Reported Seawater 6 2.82 (10-3) Balawat et al. (1976)
Phosphate Buffer
Solution
11.5 1.21 (10-2)
Bunyaviridae hantavirus
(Hemorrhagic)
Not Reported Cell Free Media 4 1.70 (10-3) Hardestam et al. (2007)
20 2.50 (10-2)
37 3.47 (10-2)
Not Reported 23 6.40 (10-3 Kallio et al. (2006)
4 1.20 (10-3)
23 6.50 (10-2)
4 2.60 (10-3)
Bunyaviridae hantavirus
(Hemorrhagic)
Not Reported Cell Free Media 4 1.00 (10-4) Hardestam et al. (2007)
20 2.60 (10-3)
37 1.19 (10-2)

1.3.4. Soil

1.4. Treatment

Table 10: Inactivation of Health-related Microbes in Water by Free Chlorine
Microbe Water Cl2 Residual (mg/l) Temp(°C) Time(min) Reduction(%) Estimate Cta References
Bacteria
pH = 7.0
E. coli BDFb, < 7umc 0.5 5 30 NDd 0.9 Berman et al, 1988
E. coli BDF, > 7ume 0.5 5 30 ND 2.7 Berman et al, 1988
M. chelonei BDF 0.3 25 60 40 >>60 Carson et al, 1978
M. chelonei 0.7 25 60 99.95 46 Carson et al, 1978
M. chelonei BDF 1 ? 60 96 ca.80 Pelletier and Du Moulin, 1987
M. fortuitum BDF 0.15 ? 60 0 >720 Pelletier and Du Moulin, 1987
M. fortuitum BDF 1 ? 30 99.4 ca.28 Pelletier and Du Moulin, 1987
M. intracellulare BDF 0.15 ? 60 70 >>480 Pelletier and Du Moulin, 1987
pH > 7.0
E. coli BDF 0.1 23 3.5 90 0.6 Hass et al, 1986
E. coli BDF 0.1M KNO3 0.1 23 0.8 90 0.15 Hass et al, 1986
Microbe Water Cl2 Residual (mg/l) Temp(°C) Time(min) Reduction(%) Estimate Cta References
Viruses
pH <= 7.0
Parvo- H-1 PBS 0.2 20 6 99.9 0.53 Churn et al,1984
Parvo- H-1 PBS 0.2 10 11 99.9 0.85 Churn et al,1984
Hepatitis A BDF 0.42-0.06 25 0.7 99.99 ca. 3.0 Grabow et al, 1983
Hepatitis A BDF 0.5 5 6.5 99.99 ca. 1.8 Sobsey et al, 1988
Coliphage MS2 BDF 0.5 5 1.2 99.99 ca. 0.25 Sobsey et al, 1988
pH > 7.0
SA11, disp. BDF ca. 0.5 5 1.1-1.65 99 0.63 Berman and Hoff, 1984
SA11, cell ass. BDF ca. 0.5 5 2.4-4.4 99 1.8 Berman and Hoff, 1984
Human rota effluent 1.1 15 15 40 >>15 Harekah and Butler, 1984
Human rota effluent 2.2 15 10 60 >>15 Harekah and Butler, 1984
Rota, SA11 BDF 0.1 4 0.5 99.9 0.03 Vaughn et al, 1986
Rota, Wa BDF 0.1 4 0.65 99.9 0.03 Vaughn et al, 1986
Rota, SA11 BDF 0.4-0.28 25 1.1 99.99 ca. 4.0 Grabow et al, 1983
Hepatitis A BDF 0.4-0.28 25 2.5 99.99 ca. 5.5 Grabow et al, 1983
Hepatitis A BDF 0.5 5 49.6 99.99 ca. 12.3 Sobsey et al, 1988
Coliphage MS2 BDF 0.5 5 26.5 99.99 ca. 6.9 Sobsey et al, 1988
Microbe Water Cl2 Residual (mg/l) Temp(°C) Time(min) Reduction(%) Estimate Cta References
Protozoan Cysts
pH <= 7.0
G. lamblia BDF 1.0-4.0 5 3.0-32 90 90-170 Jarroll et al, 1981
G. lamblia BDF 1.5 25 47 99 <15 Jarroll et al, 1981
G. lamblia BDF 2.5 5 19-26 90 ca. 120 Rice et al, 1982
G. lamblia BDF 0.2-3.0 5 99 54-87 Hibler et al, 1987
G. lamblia BDF 0.2-3.0 5 99 83-133 Hibler et al, 1987
G. muris BDF 2.5 5 30 90 >150 Hibler et al, 1987
G. muris BDF 23.8-78.5 f 5 5.7-42.6 99 449-1012 Leahey et al, 1987
G. muris BDF 2.8-7.1 g 25 3.6-16 99 25.5-44.8 Leahey et al, 1987
G. muris BDF 4.4 25 16.3 99 71 Leahey et al, 1987
N. gruberi BDF 2.64 25 2.8 99 7.3 Rubin et al, 1983
N. gruberi BDF 2.2 25 5.2 99 11.4 Rubin et al, 1983
Cryptosporidium gut homog. in PBS 30,000 f 4 18 hr <95 >>18 hrs Campbell et al, 1982
pH > 7.0
G. lamblia BDF 0.2-3.0 5 99 119-192 Hibler et al, 1987
G. muris BDF 2.5 5 48 90 >150 Rice et al, 1982
G. muris BDF 11.1 25 15.6 99 177 Leahey et al, 1987
Naegleria(2 species) 0.5-1.0 25 1-3 hr 99.99 12-18 de Jonckheere and van de voorde, 1976
Acanthamoeba(2 species) 4.0-8.0 25 24 hr 99.99 960-7200 de Jonckheere and van de voorde, 1976
N. gruberi BDF 15.4 25 15.4 99 177 Rubin et al, 1983

a: product of disinfectant concentration (C) in mg/l and contact time (t) in minutes for 99% inactivation
b: BDF: buffered demand free
c: <7um: with <7um particles
d: ND: Not done or no data
e: >7um: with >7um particles
f: Not to be used for Drinking water due to residual level greater than 2 mg/L as stipulated by EPA
g: Not recommended for Drinking water due to residual range being greater than 2 mg/L as stipulated by EPA
(Sobsey, 1989)

Table 11: Inactivation of Health-related Microbes in Water by Chloramines
Microbe Water Cl2 Residual (mg/l) Temp(°C) Time(min) Reduction(%) Estimate Cta References
Bacteria
pH <= 7.0
S. typhimurium & S. sonnei 1% sewage 0.4-1.5 20 NDb 90 8.5 Snead et al, 1980
M. fortuitum BDFc 3.25 20 50 90 2667 Engelbrecht et al, 1977
pH > 7.0
E. coli BDF 1.9-2.2 5 51-59 99 113 Scarpino, 1984
S. typhimurium & S. sonnei 1% sewage 0.4-1.5 20 ND 90 40 Snead et al, 1980
Viruses
pH > 7.0
Polio 1 BDF 5-22 5 170 99 1420 Scarpino, 1984
Polio 1 1° effl. 1-10 25 60-308 99 ca. 345 Fujioka et al, 1983
Hepatitis A BDF 10 5 117 99.99 ca. 592 Sobsey et al, 1988
Coliphage MS2 BDF 10 5 >>60 ca. 2100 Sobsey et al, 1988
Rotavirus SA11 dispersed BDF 10 5 366-402 99 4034 Berman and Hoff, 1984
Rotavirus SA11 cell-assoc. BDF 10 5 570-636 99 6124 Berman and Hoff, 1984
Protozoan Cysts
pH <= 7.0
G. muris BDF 1.5-2.6 3 188-296 99 430-580 Meyer, 1982
G. muris BDF 6.35 5 220 99 ca. 1400 Rubin, 1988
G. muris BDF 1.5-30 15 99 ca. 1000 Rubin, 1988
pH > 7.0
G. muris BDF 1.5-30 15 99 ca. 600 Rubin, 1988

a: product of disinfectant concentration (C) in mg/l and contact time (t) in minutes for 99% inactivation
b:ND: Not done or no data
c: BDF: buffered demand free
(Sobsey, 1989)

Table 12. Reduction Value (log10) by Filtration
Microbe Reduction Value (log10) Reference
Minimum a Maximum b
Porous ceramic filtration
Total Coliform 2 Lantagne 2001
E. coli 2 Brown 2007
Klebsiella terrigena 6 Sobsey 2002
Polioviruses 0.5 4 Sobsey 2002
Rotaviruses 0.5 4 Sobsey 2002
Cryptosporidium parvum 4 6 Lantagne 2001
Giardia lamblia 4 6 Lantagne 2001
Biosand filtration
E. coli 1 3 Hijnen 2004, Elliott 2008
Clostridia 1 3 Hijnen 2004, Elliott 2008
Echovirus 12 0.5 3 Hijnen 2004, Elliott 2008
MS2-bacteriophages 0.5 1.5 Hijnen 2004, Elliott 2008
PRD1-bacteriophages 0.5 2 Hijnen 2004, Elliott 2008
Cryptosporidium parvum 2 5 Hijnen 2004
Giardia lamblia 2 5 Hijnen 2004

a: expected in actual field practice when done by relatively unskilled persons who apply the treatment to waters of varying quality and where there are minimum facilities or supporting instruments;
b: by skilled operators who are supported with instrumentation and other tools to maintain the highest level of performance in waters of predictable and unchanging quality.

2. Human Environment Exposure Parameters

2.1. Ingestion

2.1.1. Drinking Water

Table 13: Estimated Combined Directa & Indirectb Community Water Ingestion via EPA Exposure Factors Handbook
Population Age Number of Subjects Mean (90% CI) c (mL/person/day) 95th (90% BI) d (mL/person/day)
United States People Birth to <1 month 91 184 (117-251) 839 (638-859)
1 to <3 months 253 227 (180-274) 896 (878-1022)
3 to <6 months 428 362 (322-401) 1056 (1043-1170)
6 to <12 months 714 360 (328-392) 1055 (1008-1254)
1 to <2 years 1040 271 (253-289) 837 (754-925)
2 to <3 years 1056 317 (298-337) 877 (828-939)
3 to <6 years 4391 380 (365-394) 1078 (1053-1109)
6 to <11 years 1670 447 (417-476) 1235 (1148-1317)
11 to <16 years 1005 606 (562-651) 1727 (1615-1780)
16 to <18 years 363 731 (633-828) 1983 (1843-2128)
18 to <21 years 389 826 (746-906) 2540 (1908-2934)
>21 years 9207 1104 (1074-1134) 2811 (2732-2924)
>65 years 2170 1127 (1073-1180) 2551 (2500-2637)
All ages 20,607 926 (903-949) 2544 (2500-2584)

a Direct water: water ingested directly as a beverage.
b Indirect water: water added in preparation of food or beverages.
c 90% CI: 90% confidence interval about the estimated means.
d 90% BI: 90% bootstrap interval about the estimated percentiles.
Source of data: 1994-1996 and 1998 USDA Continuing Survey of Food Intakes by Individuals (CSFII).
(Kahn H.D. and Stralka K., 2009)

2.1.2. Recreational Water

Table 14. Water Ingestion by selected groups of swimmers

Original survey data can be obtained by this link.

Population Age Number of Subjects Average water ingestion (mL/45 minute) Standard deviation
United States Adults Older than 18 years old 12 16 19
United States Non-adults 18 years old and younger 41 37 31

a: Non-parametric Wilcoxon Rank Sum test was applied for statistical analysis.
b: The comparison between adults and non-adults are significantly different at 5% level. The comparison between different gender groups was evaluated and not significant.

(Dufour et al, 2006)

References Dufour A, Evans O, Behymer T and Cantu R. (2006) Water ingestion during swimming activities in a pool: A pilot study. Journal of Water Health. 04.4: 425-430. Full text

2.2. Inhalation

2.3. Contact

Table 15: The numbers of hand contacts with the eyes, lips and nostrils observed during a continuous 3-hour period for ten subjects
Subject Eyes Lips Nostrils Total
1 0 0 3 3
2 4 2 1 7
3 2 12 4 18
4 1 1 20 22
5 10 22 15 47
6 13 33 8 54
7 17 15 27 59
8 6 31 28 65
9 9 52 30 91
10 12 72 20 104
Mean 7.4 24 16 47
Mean Rate (hr-1) 2.47 8.0 5.33 15.7
Standard Deviation 5.7 24 11 35
Standard Deviation Rate (hr-1) 1.9 8.0 3.7 11.7

(Mark Nicas, University of California Berkeley)

2.4. Transport Parameters