Environmental Toxicology Diary

In several previous posts, I have described a lot of things related to the epidemiological study. As matter as fact, I have explained various kind why in several factors, epidemiology can only build an association between a suspected etiological factor with an observed response. There are several elements make epidemiological study can not establish a solid and strong relationship,they are bias, observation bias and selection bias, confounding factor. In epidemiology study, the decision about association between the causative factor and the observed disease or illnese is aided by the indicator such as attributable risk and relative risk. I suggest you visit those pages to understand the idea behind them.

Now, since epidemiology study can only build an association, and also have a high degree of variability, of course a support study will be helpful to make relationship clearer. This in advance will help in establishing a safety threshold value in which individuals are allowed to get exposed within a specific period of time. This supportive study is done in a controllable environment by using animal as the object of experimentation. I think you all have already known this, its called toxicology study.

The controlled environment is made to be mimic like in the real environment. The animal, usually rats or mice, is fed by a suspected causative agent, toxic chemicals either in a single high dose (one time) to determine acute effect, or by continous and multiple times within a period of time. Toxicology study may be conducted within days (14 days), usually for acute study to months or years, for chronic study. The feeding may via injection, dermal contact, ingestion (by food through mouth) or by inhalation (gas).

Upon the study, the response is being watched, monitored and recorded. The observed effect may then be used to build relationship between a particular toxic agent to the disease or illness. It must be noted that since this study involved animal, there has to be a method to equalize the result of this study with human being anatomy. Its called extrapolation data, I’ll talk about that later. The most important thing is, this study is used to get the dose on which the response or effect is observed, and then set up the relationship between the suspected causative agent with the disease or illness (cause-effect relationship), and the last, try to extrapolate data in conjunction with epidemiological study. So both epidemiology study and toxicology study are complementing each other. I will cover more about the method later.

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