Toxic agents asphyxiates

Toxic agents cause injuries in different ways and have been categorized into seven types (see Figure 5-1) asphyxiates, irritants, systemic poisons, anesthetics, neurotics, corrosives, and carcinogens. 

Chemical asphyxiates are toxic agents which enter into reactions to cause histotoxic hypoxia. These chemicals prevent the red blood cells from carrying oxygen. Some more familiar chemical asphyxiates are carbon monoxide, nitrites, hydrogen sulhde, and aniline. 

LPG is considered to be non-toxic witli no chronic effects, but the vapour is slightly anaesthetic. In sufficiently high concentrations, resulting in oxygen deficiency, it will result in physical asphyxiation. The gases are colourless and odourless but an odorant or stenching agent (e.g. methyl mercaptan or dimethyl sulphide) is normally added to facilitate detection by smell down to approximately 0.4% by volume in air, i.e. one-fifth of the lower flammable limit. The odorant is not added for specific applications, e.g. cosmetic aerosol propellant. 

To a large extent, therefore, the toxicities of esters tend to be those of their hydrolysis products. Two physical characteristics of many esters that affect their toxicities are relatively high volatility, which promotes exposure by the pulmonary route, and good solvent action, which affects penetration and tends to dissolve body lipids. Many volatile esters exhibit asphyxiant and narcotic action. As expected for compounds that occur naturally in foods, some esters are nontoxic (in reasonable doses). However, some of the synthetic esters, such as allyl acetate, have relatively high toxicities. As an example of a specific toxic effect, vinyl acetate acts as a skin defatting agent. 

These agents interfere with the ability of the blood to transport oxygen. Consider all blood agents as toxic at high concentrations. Exposure can lead to rapid asphyxiation and death. Symptoms can include respiratory distress, vomiting, diarrhea, vertigo, and headaches. Fresh air and respiratory therapy may help some victims. Cyanide would be an example of a blood agent. 

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