Pathogens & Contaminants 1 Corinne Waelti, seecon international gmbh.

Pathogens & Contaminants


1

Corinne Waelti, seecon international gmbh


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Contents

1. Introduction

2. Characteristics of Pathogens and Contaminants

3. Pathogens

4. Contaminants

5. References

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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.

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1. Introduction



Types of Pathogens and Contaminants

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Pathogens

•Bacteria• e.g. Salmonella,

Escherichia coli, Campylobacter

•Viruses• e.g. Rotavirus,

Hepatitis•Parasitic protozoa

• e.g. Giardia•Helminths (worms)

• e.g. Trichuris trichiura

Microorganisms

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



Sources of Pathogens and Contaminants

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Source: CONSERVATION ONTARIO (2009)

•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: BUCHANAN et al. (2010)



Dispersion of Pathogens and Contaminants

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Source: WAL (2010)

Migration of contaminants in an unconfined (left) and a confined (right) aquifer.

Adapted from FREEZE et al. (n.y.)

Movement of insoluble contaminants in ground water:

Oil spills (lighter than water) accumulate on the water table and spread horizontally.



General Effects of Pathogens and Contaminants

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Drinking water contamination:

•Poor drinking water quality

•Loss of community’s drinking water supplies

•High costs for restoration and alternative drinking water supplies

•Health problems

Impacts on the environmental system by contaminants:

•Loss of ecosystem functions

Examples for related economic effects:

•Less revenue by fisheries

•Less revenue from tourism

Examples for related economic effects:

•Higher health expenses

•Restricted work force



Transmission & Health Risks of Disease

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3. Pathogens

Source: HESPERIAN & UNDP (2004)

Faecal-oral transmission routes:•Fingers•Flies and other insects•Fields (agriculture)•Food•Fluids

Health risks:Gastrointestinal symptoms such as diarrhoea, vomiting and stomach cramps



Probability of Causing Infections

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3. Pathogens

Amount and variability of pathogens

Long latency periods

Persistence in the environmentLow minimal infective doses

Little or no human immunity

SHUVAL et al. (1986)



Probability of Causing Infections

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3. Pathogens

Sanitation system

Amount and variability of pathogens

Long latency periods

Persistence in the environmentLow minimal infective doses

Little or no human immunity

Source: http://2.bp.blogspot.com/-2yIT8xt_stM/TwtB4J9sBqI/AAAAAAAACmY/s_6-9HHksUA/s1600/Istanbul%20Toilet.gif [Accessed: 05.06.2012]

SHUVAL et al. (1986)



Health Risks related to contaminated Groundwater

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4. Contaminants

Possible health risks:

•Cancer

•Liver, kidney and nerve problems

•Birth defects

•Learning disabilities in children

Source: WALLIN (1997)

Source: http://www.thewaterchannel.tv/tutorial/section_4/6.html



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5. ReferencesBUCHANAN, 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-developing-countries-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].

Pathogens & Contaminants 14

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