Types of Toxic Response

Although many different agents may damage the lung, the patterns of cellular injury and repair are relatively constant, and most fall into one or more of the categories described below. 

Perhaps one of the most obvious and familiar chemical effects is irritation caused by volatile compounds such as ammonia or chlorine gas. Such irritation, especially 

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Toxicologists do not, however, have convincing evidence that every type of toxic response to a chemical observed in species of laboratory animals will also be expected to occur in similarly exposed human beings. To make matters more complicated, there are many examples of different species of laboratory animals exhibiting different responses to the same chemical exposure ... 

It is necessary to appreciate both for a mechanistic view of toxicology. The first of these includes the absorption, distribution, metabolism, and excretion of xenobiotics, which are all factors of importance in the toxic process and which have a biochemical basis in many instances. The mode of action of toxic compounds in the interaction with cellular components, and at the molecular level with structural proteins and other macromolecules, enzymes, and receptors, and the types of toxic response produced are included in the second category of interaction. However, a biological system is a dynamic one, and therefore a series of events may follow the initial response. For instance, a toxic compound may cause liver or kidney damage and thereby limit its own metabolism or excretion. 

It is currently uncertain if this phenomenon occurs across all chemical types, species of animal or cell, and type of toxic response. 

Thus, although all these toxic responses may have a biochemical basis, they have been categorized according to the manifestation of the toxic effect. Therefore, although there will be overlap between some of the types of toxic response, for the purposes of this discussion, it is convenient to divide them into the following ... 

There are various types of toxic response, which the liver sustains and which reflect its structure and function. Viewed simply, liver injury is usually due either to the metabolic capabilities of the hepatocyte or involves the secretion of bile. 

The types of toxic response shown by the lungs are briefly discussed below. 

List the different types of toxic response, which chemicals may cause. 

The liver shows the following types of toxic response steatosis (fatty liver), cytotoxic damage, cholestatic damage, cirrhosis, vascular lesions, liver tumors, and proliferation of peroxisomes. 

The other type of toxic response we shall discuss is the continuous one. In broadest terms we refer to responses in which not the incidence of effect but its severity increases with increasing dose. This is best illustrated with an example let s use the solvent carbon tetrachloride and data from a 90-day toxicity study (Figure 4). 

Toxicologists do not, however, have convincing evidence that every type of toxic response to a chemical observed in species of laboratory... 

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