Dose-Response Relationship (Hubungan Dosis-Efek)

What is dose response relationship?
What is the purpose of dose response relationship?
What are the methods to determine dose response relationship?
What does it has something to do with acute and chronic test?
What is dose response curve?
Why is the curve very important?
What are variables of toxicity?

What is dose response relationship?
Its just ordinary relationship for a test or observation, for a given dose, what are responses of the object of study (animal or humans), what are the observed effect (organ structure changes, death, etc.) for a given dose.

What is the purpose of dose response relationship?
It helps to set safety levels of exposure for chemicals or toxicants in order to protect us from possible harmful effects.

What are the methods to determine dose response relationship? 
We can use epiemiological studies, chemical analogy and animal experimentation.

What does it has something to do with acute and chronic test?
Acute and chronic are types of observation for toxicity of a substance.

What is dose response curve?
It is a curve to visually recognize the relationship between increasing doses (horizontal axis) and increasing response or effects (vertical axis). Generally, as the dose increases, so does the number of indviduals exhibiting the measured response.

Why is the curve very important? 
Look at the picture above. It is important to set threshold value. Threshold is the dose below which no effect is detected or above which an effect is first observed. This is useful in extrapolating animal data to humns and calculating what may be considered a safe human dose for a given toxic substance.

Assuming that humans are as sensitive as the test animal used, Safe Human Dose (SHD) is ThD (Threshold Dose) multiplied by 70 kg, considered as average weight of a man.

SHD = (ThD x 70 kg)/SF

SF is safety factor (ranges from 10 to 1,000) depends on data and test used to obtain ThD.

SHD is only based upon a specific effect or measured effect as the test purpose. Usually only one effec is chosen as a measure of response, and therefore, threshold applies only to the response being measured.

What are variables of toxicity?
1. Dose Time relationship
2. Routes of exposure and physical-chemical factors
3. Interspecies and intraspecies variability

Reference:
Kent, C. 1998. Basics of Toxicology. John Wiley & Sons, Inc. New York
http://www.emcom.ca/science/dose.shtml
http://www.graphpad.com/curvefit/introduction89.htm

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