2/2/99

Public Health

 

Sewage p750-753

Water Purification

-disinfection and softening of water

 

Corrosion correction

-corrosion and oxidization of iron pipes which supplies water to homes and businesses can ruin water quality and can act as an area where bacteria can grow (i.e. Mycobacterium, TB, Haemophilus, Logionella pneumophilla)

-Bitumen--lining of iron pipes made of inert coal and tar product

-cement also has been used to line pipes, but it has a tendency to crack

-the best combo is cement and bitumen

 

Fluoridation--controversial

-accidentally discovered in areas where tooth decay was low

-significantly lowers dental caries

-kills strep mutans which cause dental caries

-fluorine is highly corrosive--in excess can destroy tooth enamel and respiratory lining in high quantities

-in low quantities, it is very helpful to prevent tooth decay

-have added fluorine to tooth paste

-dentists are hurt by fluorine b/c occurrence of cavities has decreased

-Hydrofluoric acid used in glass etching--highly corrosive

 

Chemical analysis of water--must be done and made available to public, radiation has been found in some water supplies

 

Microbial Analysis of Water

-p 7474-749

-must be done on a daily basis

-sample must sit 24 hours

-look mainly for E. coli--presence indicates fecal contamination

-methods using lactose broth tubes, EMB (eosin-methylene blue)

agar (E. coli will show green metalic sheen), filter paper

 methods # of colonies/100mL

-1 colonly/100mL water is said to be contaminated and must be rechlorinated and retreated before human consumption

 

fig 26.17

-water in our homes is not sterile

      -presumptive tests

      -confirmed tests

      -completed tests

 

Insecticides/Pesticides in Water, soil, Air

-once gets into water (eventually all does), affects the food chain

-essential evils

-DDT--chlorinated hydrocarbon

      -1948--Hans Muller got Nobel Prize for its development

      -no longer used in US since 1974

      -still seen as toxin in soil

      -has relatively long 1/2 life=15yrs

      -US imports DDT laced foods

      -most extensively studied insecticide

      -800 million tons dumped on American soil over time resulting in endangered species (penguins, falcons, seals, etc.)

 

Bioaccumulation

-increased concentration of insecticides as move up the food chain

-humans at the top of the food chain get exposed to increased concentrations

-animals w/more fat tend to retain more chemicals du to their fat solubility

 

Carbamates

-1/2 life of weeks

-liquid sevin

-more expensive, difficult to manage, must use more often

-biodegradable-better than chlorinated hydrocarbons

 

Oranophosphates

-1/2 life of months