By injection or infusion - bypassing the usual route of ingestion or inhalation.\n
Lecture 1 3 ss-1
Entry and Fate of Chemicals
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)
The Lungs Primary function is to take in oxygen and transport it to :1. the skeletal system2. the digestive system3. the circulatory system4. the endocrine system
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.
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
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
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.
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.
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
Recognition of Human Hazard Exposures1. 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
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/
Recognition of Human Hazard Exposures3. Environmental exposure databases4. Sentinel (watching) event strategies5. 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
GIS remote sensing and graphical analysis http://nbii-nin.ciesin.columbia.edu/jamaicabay/maps.html Impervious Surfaces in the Jamaica Bay Estuary
Recognition of Human Hazard Exposures6. 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.
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.
Deposition of particulates in the respiratorytract depends on the _____, _____, and ____1. Lipid solubility, size, weight2. Water solubility, weight, shape3. Size, shape, density4. Shape, lipid solubility, water solubility
What is the #1 killer of inhaled material?► carbon monoxide► cigarette smoke► dust► pollen
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?