Pathogens & Contaminants
Corinne Waelti, seecon international gmbh
Pathogens & Contaminants
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Pathogens & Contaminants
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Contents
1. Introduction
2. Characteristics of Pathogens and Contaminants
3. Pathogens
4. Contaminants
5. References
Pathogens & Contaminants
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1. Introduction
The overall Problem
Substances such as pathogens (microorganisms) and contaminants
(chemicals and metals) in drinking water may harm both public health
and the environment. In developing countries, the contamination of
drinking water with pathogens is the major factor for prevalence of
diseases.
Most often, faeces infiltrating drinking water sources are responsible
for contamination with pathogens. Contaminants in drinking water may
originate from human activities and natural processes.
Pathogens & Contaminants
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2. Characteristics of Pathogens and Contaminants
Types of Pathogens and Contaminants
Pathogens
•Bacteria
• e.g. Salmonella,
Escherichia coli,
Campylobacter
•Viruses
• e.g. Rotavirus,
Hepatitis
•Parasitic protozoa
• e.g. Giardia
•Helminths (worms)
• e.g. Trichuris
trichiura
Contaminants
• Inorganic chemicals
• e.g. nitrate, arsenic,
fluoride, chloride
• Organic chemicals
• e.g. petro-chemicals
(oil, diesel), solvents,
drugs, pesticides
• (Heavy) metals
• e.g. cadmium,
copper, lead, mercury
 Microorganisms
Pathogens & Contaminants
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2. Characteristics of Pathogens and Contaminants
Sources of Pathogens and Contaminants
Source: BUCHANAN et al. (2010)
• Underground storage tanks
• Chemical storage
• Accidental spills of hazardous
materials
• Spreading of sewage treatment
sludge
• Septic systems
• Animal feedlots
• Storage and spreading of road
salt
• Underground pipelines or
sewers
• Use and spilling of fertilisers
and pesticides
• Landfills
• Private and abandoned wells
Source: CONSERVATION ONTARIO (2009)
Pathogens & Contaminants
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2. Characteristics of Pathogens and Contaminants
Dispersion of Pathogens and Contaminants
Migration of contaminants in an
unconfined (left) and a confined
(right) aquifer.
Movement of insoluble
contaminants in ground water:
Oil spills (lighter than water)
accumulate on the water table
and spread horizontally.
Source: WAL (2010)
Pathogens & Contaminants
Adapted from FREEZE et al. (n.y.)
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2. Characteristics of Pathogens and Contaminants
General Effects of Pathogens and Contaminants
Drinking water contamination:
•Poor drinking water quality
•Loss of community’s drinking
water supplies
Impacts on the environmental
system by contaminants:
• Loss of ecosystem functions
•High costs for restoration and
alternative drinking water
supplies
•Health problems
Examples for related economic
effects:
Examples for related economic
effects:
• Higher health expenses
• Less revenue by fisheries
• Restricted work force
• Less revenue from tourism
Pathogens & Contaminants
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3. Pathogens
Transmission & Health Risks of Disease
Faecal-oral transmission routes:
• Fingers
• Flies and other insects
• Fields (agriculture)
• Food
• Fluids
Health risks:
Gastrointestinal symptoms
such as diarrhoea, vomiting
and stomach cramps
Source: HESPERIAN & UNDP (2004)
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3. Pathogens
Probability of Causing Infections
Persistence in
the environment
Low minimal
infective doses
Little or no
human immunity
Amount and
variability of
pathogens
Long latency
periods
SHUVAL et al. (1986)
Pathogens & Contaminants
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3. Pathogens
Probability of Causing Infections
Sanitation
system
Persistence in
the environment
Low minimal
infective doses
Little or no
human immunity
Source: http://2.bp.blogspot.com/2yIT8xt_stM/TwtB4J9sBqI/AAAAAAAACmY
/s_69HHksUA/s1600/Istanbul%20Toilet.gif
[Accessed: 05.06.2012]
Amount and
variability of
pathogens
Long latency
periods
SHUVAL et al. (1986)
Pathogens & Contaminants
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4. Contaminants
Health Risks related to contaminated Groundwater
Possible health risks:
• Cancer
• Liver, kidney and nerve
problems
• Birth defects
• Learning disabilities in
children
Source: WALLIN (1997)
Source:
http://www.thewaterchannel.tv/tutorial/s
ection_4/6.html
Pathogens & Contaminants
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5. References
BUCHANAN, B., DE LA CRUZ, N, MACPHERSON, J., WILLIAMSON, K. (2010): Water Wells that Last for Generations. Edmonton:
Alberta Agriculture and Rural Development. URL: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/wwg404
[Accessed: 05.06.2012].
CONSERVATION ONTARIO (Editor) (2009): Wellhead Protection Areas. Newmarket: Conservation Ontario. URL:
www.conservationontario.ca/source_protection/files/ODWSP%202009%20Finals/ODWSP_FAQS_wellhead_EN_2009_02_27_WEB.pdf
[Accessed: 06.06.2012].
FREEZE, R.A., ATWATER, J., LIEBSCHER, H. (n.y.): Water Stewardship . Ground Water Resources of British Colombia. Victoria: The
Province of British Columbia. URL:
http://www.env.gov.bc.ca/wsd/plan_protect_sustain/groundwater/gwbc/C05_contamination.html [Accessed: 05.06.2012].
HESPERIAN FOUNDATION (Editor); UNDP (Editor) (2004): Sanitation and Cleanliness for a Healthy Environment. Berkeley: The
Hesperian Foundation. URL: www.unwater.org/downloads/EHB_Sanitation_EN_lowres.pdf [Accessed: 05.06.2012].
SHUVAL H.I., ADIN, A., FATTAL, B., RAWITZ, E., YEKUTIEL, P. (1986): Wastewater Irrigation in Developing Countries. Health
Effects and Technical Solutions. Washington, D.C.: The World Bank. URL:
http://documents.worldbank.org/curated/en/1986/05/440564/integrated-resource-recovery-wastewater-irrigation-developingcountries-health-effects-technical-solutions [Accessed: 05.06.2012].
WAL, A. van der (2010): Understanding Groundwater & Wells in Manual Drilling. Instruction Handbook for Manual Drilling Teams
on Hydro-geology for Well Drilling, Well Installation and Well Development. Papendrecht: Practica Foundation. URL:
www.unicef.org/wash/files/04.pdf [Accessed: 06.06.2012].
WALLIN, R. (1997): Wellhead Protection: A Guide for Arizona Communities. TUCSON: Arizona Department of Environmental
Quality, Water Quality Division. URL: http://www.unicef.org/wash/files/04.pdf [Accessed: 05.06.2012].
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Pathogens & Contaminants
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