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Basics Arsenic

What is arsenic?

  • Arsenic is a so called half-metall; As (No 33 of perodic system)
  • As mainly occurs in minerals; 565 different compounds are known
  • As is available world wide (ubiquitous)  in soil, rocks, water, air
  • in animals, plants as well as also in human beings
  • Solvable arsenic oxids are very toxic which are prominent in groundwater ;  arsenic(III) = arsenite; arsenic(V) = arsenate
  • Arsenic poisening  is the second most important health hazard related to drinking water  / Pathogenic microorganisms are the No.1 health hazard

For what  arsenic is used?

  • Arsenic is used already since more than 2,000 years
  • Used as component of medicals e.g. malaria, tubercullosis, sleeping thickness;  up-to-date to treat special kinds of leukemia (Trisonex, USA)
  • Fungiicide in forrestry, pesticides in winegrowing, rat poison
  • Electronic industry  (semiconductor, !! wafer of solar panels, accumulators
  • From middle age until 19th century:  Arsenic was very important as poison to kill humans because the poison could not be indicated in this time

Arsenic risk for People World wide

More than 140 Mio People
  1. Bangladesh 30 up to 100 Mio
  2. Indien (Westbengal, Bihar) about 40 Mio
  3. Vietnam (Red river, Mekong) About 10 Mio
  4. Myanmar (Irrawady) About 3.4 Mio
  5. Nepal About 3 Mio
  6. Cambodia (Mekong Floodplian) Up to 300,000
  7. China 5 upto 14 Mio
  8. Argentinia (Chaco-Pampean) Up to 2 Mio

Arsenic affected countries world wide

• David Frederics, WHO consultant
• IARC International Agenca for Research of cancer (WHO), 2004
• Drinking water Engineer 2/29/2009
• Sandia Natioanl Laboratories; Handbook Arsenic Removal from Drinking Water, 2009


Arsenic and fluorider risk areas of Lao PDR

Arsenic risk areas in Lao PDR

Arsenic_NDlabel_newSources: OurWorld Rural Development Co., Ltd (Vientiane / Laos 2013)


Fluoride risk areas in Lao PDR
Fluoride_NDlabel_newSources: OurWorld Rural Development Co., Ltd (Vientiane / Laos 2013)


Sources of arsenic in groundwater

Geogenic rich and enriched minerals in alluvial river plains
  • E.g. the river plains (river basins)  of Ganges-Bramaputra (Nepal, India, Bangladesh), of Mekong (China, Lao PDR, Cambodia (!!), Vietnam), of Red River (Vietnam), of Irrawady (Myanmar)
  • Arsenic wash-out from wethering arsenic rich sulfide minerals of higher mountains (e.g. Himalaya) and transported arsenic adsorbed at iron-oxy-hydoxide and clay to the alluvial areas
  • Arsenic is deposed with the alluvial of the river plains and is available in the aquifers there e.g. adsorbed at iron-oxy-hydroxids and in sulfide minerals
  • The discharing mechanism into the groundwater are different (aerobic and anaerobic) anaerobic mechanism = higher content of As(III); aeraobic: lower content of As(III)
Geogenic rich and enriched minerals in volcanic areas
  • E.g. Attapeu area of Lao
  • e.g. discharging of arsenic from sulfide minerals by oxydation
Anthropogenic sources of arsenic
  • In connection with mining activities of e.g. copper, gold, lead
  • e.g. connected with inefficient water treatment and wash out of tailing disposals
  • affected area:  e.g. former copper mining in the area of Nakon Si Thamarat / South Thailand

Sources of arsenic in groundwater

 Health risks of arsenic contamination

 Health risks of arsenic contamination


Pathogenic Microorganisms (pathogens)

Pathogens caused deseases are the world wide first most important health hazard related to drinking water
  • Pathogens are microorganisms causing illness
  • Pathogens includes bacteria (e.g. Salmonella, Escherichia coli, Cholera), viruses (e.g.Hepatitis) and parasites  (protozoa and worms)
  • Fecals of human and animals are the most important sources of pathogens
  • Main deseases caused by water-based pathogens:
  1. Acute diarrhoea and gastroenteritis
  2. Cholera
  3. Hepatitis
4 billion cases of diarrhoea cause 2.2 million deaths, mainly among children under the age of five
Source: WHO (2000), The world health report: Making a difference


Pathogenic Microorganisms (pathogens)
Source: New Zealand, Min. of Health 2007; Pathogens and pathways and small Drinking water supplies..

Sources of pathogenic microorganisms in water

  • Most important sources are fecals of human and animals which are discharged to water sources like ground water, surface water, soil
  • Bacteria and viruses can survive in water for more than 100 days

Requirements to prevent pathogenic caused deseases 

  • Prevent to dicharge fecals  to surface and ground water
  • Check the pathogenic pollution of water sources of drinking water
  • Disinfect  pathogenic polluted drinking water or it you not sure whether the water is polluted or not
  • Regulary clean and disinfect bottles and tanks which are used to transport and/or store drinking water
  • Keep strong hygienically rules -> AWARENESS