Exposure of humans and other

At certain times of the day, sunlight can be of such intensity that it has effects on the bodies of humans and other animals. Exposure to UV in sunlight can have both beneficial and detrimental side effects for humans, o UV-C is light below 290 nm, UV-B, light between 290 and 320 nm and UV-A 320 00 nm light. 

The hazard assessment identifies the adverse effects that a chemical may cause and investigates the relationship between their magnitude and the dose to which an organism is exposed. A major source of uncertainty is the use of data from tests on laboratory animals (or plants) to investigate toxicity to other species (including humans). There are at least four reasons why there is uncertainty in the application of test data to exposures of humans and wild animals (RCEP, 2003, pp21—22 Rodricks, 1992, ppl58-179) ... 

Azo-based dyes, known to be carcinogenic, contain easily hydrolyzed azo bonds. In the GI tract, these bonds are cleaved to yield the free aromatic amine(s) [20]. Azo reduction may also take place in the liver of humans and other mammals by reductase enzymes, but it is likely that hydrolysis in the GI tract is predominant [21]. The resultant aromatic amines are easily absorbed in the intestines. It was found that inclusion of sulfonate moieties on the aromatic amine feedstocks mitigates the toxicity, as illustrated with the azo dye Brilliant Black BN (Cl Food Black 1) in Figure 13.6. The sulfonate moieties are highly ionized in the GI tract and at environmental pHs (5-9), and their reduction products cannot penetrate the GI endothelial membranes following oral exposure. Consequently, the chemicals are poorly absorbed, and any portion that is absorbed is rapidly excreted in the urine [22, 23]. 

Exposure assessment. Determination of the level, frequency, and duration of exposure of human or other organisms to the hazardous substance. 

The toxic effects associated with PCN exposures in humans and wildlife are, in general, characteristic of effects due to chlorinated hydrocarbons such as 2,3,7,8-TCDD. For instance, chloracne, vitamin A depletion, edema and liver damage have been observed in animals exposed to TCDD. The human toxicity and mechanistic relationship of PCNs to TCDD may be useful in understanding these classes of compounds. Particularly, acute and subacute exposures of humans and cattle to PCNs may provide important clues to the toxic effects at high levels for other dioxin-like compounds. 

Humans have several variants of BuChE, and as many as 11 forms of serum BuChEs have been described. One of these forms is associated with unusual clinical responses to succinylcholin, which is used as a muscle relaxant during surgery. Low-rate exposure of humans or other organisms to organophosphates or carbamates may cause an inhibition of the BuChE, without any sign of poisoning. 

Follw-up Studies. The results of the Tarrant and Allard study (9), combined with an incident in which several dead snowshoe hares with elevated levels of As (more than 100 ppm in various tissues) were found in a treated area, prompted an intensive effort to further elucidate patterns of applicator exposure and to evaluate means of reducing exposure to humans and other animals. 

The short-term exposure of humans, animals, and plants to gaseous pollutants is more severe than that for pollutants in other matrices. Since the composition of atmospheric gases can show a substantial variation over a time, the continuous monitoring of atmospheric gases such as O3, CO, SO2, NH3, H2O2, and NO2 by in situ sampling is important. 

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