1. Entry and Fate of Chemicals

2. Inhalation Exposure
► Most important route of entry of many
biologic and chemical agents into the body.
► Inhalation exposure per event is estimated
based on:
 Duration of each event
 Inhalation rate of the exposed individual during
the event
 Concentration of the contaminant in the inspired
air.
► Airborne contaminants can be present in the:
 Gaseous phase (gases and vapors)
 Liquid phase (droplets)
 Solid phase (particulates and fibers)

3. The Lungs Primary function is to take in
oxygen and transport it to :
1. the skeletal system
2. the digestive system
3. the circulatory system
4. the endocrine system

4. Inhalation Exposure
► Uptake of gases and vapors depends on:
 Concentration and relative solubility of the
agent in water and lipids
► Depositionof particulates in the respiratory
tract depends on:
 Size, shape and density of the material
► Hostfactors influencing uptake of gases
and particulates include:
 Age, weight, sex, race, disease state,
respiratory rate.

5. Dermal Exposure
► Dermal Exposure is determined by:
 Concentration of hazardous substance in a contaminated
medium that is contacted
 Extent of contact
 Duration of such contact
► Factors influencing dermal absorption of chemicals
include:
 Molecular weight of the compound
 Solubility in water (polar) or lipids (non-polar)
 Presence of other compounds that might facilitate
passage of a chemical through skin
 Permeability of the skin
► Dermal exposure takes place during:
 Swimming or bathing in contaminated water
 Skin contact with the soil and various industrial
operations

6. Ingestion Exposure
► Exposure due to ingestion of contaminated food (&
drink) can be estimated as:
 the product of contaminant concentration in the
consumed food or drink.
 the amount of food consumed per day.
► Daily ingestion exposure estimates are calculated
in the same manner, regardless of the type of
ingested food.
► In adults, ingestion exposure is mainly due to
consumption of contaminated food and drinks
► In children, ingestion exposure is mainly due to:-
 consumption of soil
 contaminated toys

7. This includes exposure to pets…
► Last year over 50,000 calls involved the ingestion of human
medications such as painkiller medications,
antidepressants, and supplements. Your dog can snatch a
vial off a counter or gobble up pills that accidentally hit the
floor. So it is essential to keep this #1 hazard tucked away
properly.
► Also – veterinary medications, people food, pesticides,
rodenticides, insecticides, household cleaners, & garden
fertilizers.

8. Eye Exposure
► Eyeexposure results from accidental
contact of the eyes with:
 Biologic agents
 Chemical agents
 Physical agents
► Eyes
are very sensitive and affected by
minute amount of an agent.

9. Parenteral Exposure
► Parenteral exposure is usually encountered
as:
 Bites and stings by animals
 Occupational exposure among health
professionals and veterinarians from cuts and
pricks by sharp instruments (needles)
contaminated with blood pathogens.
 Illegal drug use – via needles

10. Recognition of Human Hazard Exposures
1. Measure of actual exposure
 Microenvironmental samplers
► e.g. passive samplers in homes or offices to
measure airborne lead or Carbon monoxides
 Personal monitor
► Active monitors worn by volunteers that
measure real-time concentration
 Biological measurements in human tissues
or fluids
► Determine concentration in blood, urine, hair,
saliva, sweat

11. Recognition of Human Hazard Exposures
2. Mathematical models
 Mathematical abstractions of physical reality;
create “models” based on mathematical analyses
of smaller numbers of measurements
 Three types of models used in Exposure
Assessment
1. Concentration model – estimate concentration of
pollutant in environmental media.
2. Contact model – estimate exposure or contact
between pollution and persons.
3. Dose model – estimate the internal or delivered dose,
or amount of pollutant that enters the body and that is
finally deposited in specific human tissues and fluids.
See World Health Organization: http://gamapserver.who.int/mapLibrary/

12. Recognition of Human Hazard Exposures
3. Environmental exposure databases
4. Sentinel (watching) event strategies
5. Geographic information system (GIS)
 Integrate diverse multimedia (air, soil,
water) data, geographic features, census
information, information about ecologic
regions and chemical toxicity information
into a common database with spatial
characteristics

13. GIS remote sensing and graphical
analysis
http://nbii-nin.ciesin.columbia.edu/jamaicabay/maps.html
Impervious Surfaces in the Jamaica Bay Estuary

14. Recognition of Human Hazard Exposures
6. Biologic markers
 Indicators of biological systems or
samples
 Once exposure has occurred, a
continuum of biological events can be
detected
 Serves as markers of initial exposure,
administered dose, biologically effective
dose, and altered structure or function.

15. Biological Markers
 Biological Markers can represent:-
►Marker of effect (ex. glucose)
 A change or rise in an internal substance that depending on
it’s magnitude can be seen as a potential problem or
disease
►Marker of susceptibility (presence of an allergen)
 Indication of some sort of limitation or reaction to an
external substance that is typically inherited
►Marker of exposure
 The amount of substance that is found to have interacted
with an organism.

16. Deposition of particulates in the respiratory
tract depends on the _____, _____, and ____
1. Lipid solubility, size, weight
2. Water solubility, weight, shape
3. Size, shape, density
4. Shape, lipid solubility, water solubility

17. What is the #1 killer of inhaled
material?
► carbon monoxide
► cigarette smoke
► dust
► pollen

18. Questions
► How are gases formed from landfills?
► What is the most common type of landfill?
► If you live near a landfill, is landfill gas
hazardous to your health? If so, in what
ways?
► What are the Federal regulations and laws
to protect people and how are they
enforced?