Absorption
Bioavailability
biotransformation
a chemical can produce harmful effects to one living organism while not harming another (selective toxicology).
No two individuals are the same; therefore the responseto a dose varies considering age, lifestyle, and genetics (biological variation)
Toxicity phases:
- Exposure phase
- Processing phase
- Expression phase
When an organism is exposed to a toxic substance, it follows toxicity phases. The first phase is the exposure phase, which is when a toxicant is taken up by the organism’s system via the mouth (oral), lungs (inhalation), or skin (dermal). Next is the processing phase, where the toxicant is transported and stored inside the body. The rate at how it is processed varies from person to person. Lastly, the expression phase describes the resulting effects that appear in the organism (e.g. lesion or headache). Different substances result in different symptoms.
Determining the risk of exposure to a chemical substance is invaluable to
toxicologists. The process that is used to estimate this is called risk assessment. Risk assessment is an analysis that uses mathematical equations and scientific information (e.g. health and environmental) to determine the probability of an event occurring and the magnitude of the adverse effect over a specific time. It is used by governmental agencies to determine the unacceptable level of a chemical substance, the risk of exposure to a population at a contaminated site, and the appropriate cleanup method to safeguard human health. The risk assessment process consists of four
basic steps, which are the following:
- Hazard Identification – what are the health risks caused by the chemical substance?
- Exposure Assessment – what is the amount of the chemicals substance and how many people are exposed to it?
- Dose-‐Response Evaluation – what are the health problems associated with the exposure?
- Risk Characterization – what are the health risks caused by the chemical substance in the exposed population?
RESPONSE
On-‐line resources that contain relative information
www.toxedfoundation.org/video_pg.htm
www.youtube.com/watch?v=KbOPLBYGKs8&hd=1
www.learner.org/courses/envsci/unit/text.php?u nit=6&secNum=1
www.teachersdomain.org/resource/envh10.healt h.scleroderma/