109. Health effects of microbiological and chemical water pollutants, water quality testing

Natural ingredients of water
- Iodine, fluoride, calcium, magnesium, sodium, etc.
- The calcium and magnesium content of water determines its hardness
  - Hardness should be around 5 – 35 degrees
- High sodium intake increases risk for hypertension
- Fluoride in water
  - Protects against dental caries
  - Too high level gives dental fluorosis, fragile bones
  - Level should be 0,7 – 1,2 mg/L
  - Fluoridation of drinking water may be necessary to reach optimal level
Chemical water pollutants
- Toxins from algae
- Pesticides (mercury or chloroorganic)
  - Minamata disease – due to organic mercury
    - Causes neurological symptoms
- Fertilizers (nitrate)
  - Nitrate toxicity can lead to methaemoglobinaemia / blue baby syndrome
    - Especially in infants and those with methaemoglobin reductase deficiency
  - Nitrate inhibits iodide uptake -> endemic goiter
  - Prevention: addition of methylene blue to the water
- Arsenic
- Oil
- PAHs
- Detergents
Microbiological water pollutants
- Bacterial
  - Campylobacter jejuni, campylobacter coli
  - Pathogenic e. coli
  - Salmonella typhi
  - Shigella spp, yersinia enterocolitica
  - Pseudomonas aeruginosa
  - Legionella pneumophila
- Viruses
  - Adenovirus
  - Enterovirus
  - Hepatitis A
  - Norovirus
  - Rotavirus
- Protozoa
  - Entamoeba histolytica
  - Giardia lamblia
- Worms
  - Dracunculus medinensis
- Water-born outbreaks
  - Legionella is the major cause of water-born outbreaks
  - Criteria
    - Many cases at the same time in one distribution area
    - Pathogens detectable in water or biological sample
    - No new cases after closing the distribution system
    - No new cases after disinfection
Water quality testing
- Dissolved oxygen
- pH
- Nitrates
- Total dissolved solids
- Hardness
- Faecal coliform bacteria
  - These are not pathogens, but they indicate the presence of other pathogens
  - They are so-called indicator organisms
- Phosphorous