After being busy with my theses now I am able to back to here again. Previous posts have explained the single time dose of a toxic chemical entering the ingestion tract. So this time, I would like to explain about the finite dose of barium that enters the body. As we know on the previous post, the single dose is described and the dose, and now the dose is continously enters the body or digestion organs. Read the rest of this entry »

This post relates to previous post about biotransfer factor in previous post. If you haven’t visited that post yet, I suggest you do so. I would like to provide an example on how to calculate the concentration of chemical A if not 100% is removed in the liver organ.

The keyproblem to this matter is whether BTF is dependent or independent for chemical removal in the liver or not. Depends or independent is determined by toxicology study. We can know only if the figure is confirmed as a linear function between concentration of chemical in the body with the dose as follows: Read the rest of this entry »

Bio Transfer Factor (BTF) is a constant to describe the relationship between chemical substance in a tissue and the rate of ingestion to body of particular toxic agent (chemical substance). Often, the concentration forms a linear or straight line as the rate of chemical ingestion inreases as well. Thus at this case, the BTF is constant. I will make this simpler, BTF is a ratio between the amount of chemical per amount of body weight (mg A/kg_tissue) and the rate of ingestion of chemical entering the body (mg A/day. If you do not follow previous post, you are probably unfamiliar with A, A is representing toxic chemicals. I suggest you read the example about physiologically based pharmacokinetics, part 1, part 2 and part 3, especially this example is related to those examples as well. Read the rest of this entry »

Last post we have already talked about physiologically based pharmacokinetics example part 1 and part 2. These two posts give example on how to calculate the concentration of a suspected toxic chemicals within our digestive tract inside our body. They include the scheme starting from stomach and flow blood and kidneys. Just to refresh memory, this chemical enters the body, goes passing stomach before actually absorbed by blood for metabolism and the rest is sent to kidneys to be urinated. Read the rest of this entry »

After simple calculation on previous post physiologicaly based pharmacokinetics part 1, we now try to compute the concentration of a chemical substance A in blood and in the kidney. Assume that 0.5 mg A is at equillibrium and distributed between the blood and the kidneys. Let us assume to total blood volume in rats is equal 500 ml. Under assumption that blood and water have approximately the same density (1 g/ml), 500 ml of blood is the same with 50 mg blood. Read the rest of this entry »

Stock and flow model is a practical method to predict and calculate chemical or substance concentration in a building with a simple model. However, more sophisticate approach has to be done to measure chemical concentration in human tissue, how it move and concentrated in the living thing organs, the body. Therefore physiologically based pharmacokinetic may be applied for this case. Read the rest of this entry »

We have practiced about reducing radon at controlable level with exchanging air within the building. The exercise about stock flow model in previous post can be applied to calculate the concentration on radon in our own house, of course if you have radon dosemeter. This post will drill you to understand more about stock model flow. Read the rest of this entry »

We have learned simple example to measure radon concentration in indoor building with several information known such as average annual indoor radon concentration and air change per hour. I suggest to review again the stock flow model and example part 1. Now we will practice to measure and calculate the flow rate of radon into a house that has average annual radon concentration of 20 pCi/L. How much additional airflow would be necessary to reduce the concentration in the house to become 2 pCi/L? Read the rest of this entry »

Now you have learned about a very simple example of stock model example which in the prevous post, it gave TCA example. The more advance example now is talking about radon. More information about radon can be read at Radon: risk around us. Read the rest of this entry »