Toxicology responses

Noncarcinogenic elTects include all toxicological responses except tumors. Toxicological responses and iiicchanisins vary widely, and e.xamples of these include interference with normal cell processes by displacing elements out of the cell and binding with a cell to reduce membrane penneability. However,... 

The process of identifying chemical healtli liazards should also incorporate the near term (release into tlie environment) and long term fate of the chemical health hazard following entry into the human body. Non-carcinogcnic effects include all toxicological responses except tumors. Not all tumors are cancerous. Malignant tumors are cancerous and spread, or metastasize, to surrounding structures. 

Oevere toxicological responses have been associated with certain chloro- dibenzodioxins. One of these responses is chloracne, a folliculosis first associated with skin contamination by chlorohydrocarbons in 1899 (3). Serious outbreaks of chloracne-like lesions associated with runaway reactions in the production of 2,4,5-trichlorophenol occurred in Germany in the early 1950 s (5). 2,4,5-Trichlorophenol itself does not cause acne (S), but the contaminants which may be formed in the uncontrolled production of 2,4,5-trichlorophenol are extremely potent acnegens (5). 2,3,7,8-Tetrachlorodibenzo-p-dioxin and tri- and tetra-... 

Recently, the toxicological responses of CNTs in the intra-abdominal cavity have attraded significant attention. Studies have been carried out mainly in vivo, and only three in vitro models have been tested. The significance of these studies is unknown, however, since no evidence indicating that CNTs can reach the pleural space is currently available. 

The Chemical Incident Simulator simulates the dispersion of chemical warfare agents, detector responses, the effects of protective equipment, and die human toxicological responses for large numbers of scenarios. The possibilities and potentials offered by the Chemical Incident Simulator are illustrated best with an example. 

In contrast, in the pharmacological approach to toxicology, the potential targets of toxicity are first identified (Zbinden, 1986). Then criteria for relevant effects are established, usually based on experience with reference substances, and appropriate in vivo or in vitro experimental models are selected to assess the pertinent toxicological responses. 

Having identified information about the relationship between dose of a food additive and any toxicological response, and determined an ADI, it is necessary to investigate the levels of actual doses in the human population. Exposure analysis is used to find out if any individuals have potential intakes that might exceed the ADI for a particular additive and if so, by how much. Two pieces of information are vital for this ... 

The ultimate toxicological response following exposure to a chemical substance is most commonly the result of the action of this substance on a definite site or receptor. For a given concentration of the agent at the target site, the intensity of the response will depend on the quality of the action (the intrinsic activity) and the affinity of the compound for the receptor. 

Driver CJ, Ligotke MW, Van Voris P, McVeety BD, Greenspan BJ, Drown DB. 1991. Routes of uptake and their relative contribution to the toxicological response of northern bob-white (Colinus virginianus) to an organophosphate pesticide. Environ Toxicol Chem 10 21-33. 

As illustrated in the previous chapter, the human body can be exposed to a variety of toxicants that may be present in various environmental media such as air, soil, water, or food. However, just simply being exposed to these hazardous chemicals does not necessarily translate into a toxicological response. The mammalian body has several inherent defense mechanisms and membrane barriers that tend to prevent the entry or absorption and distribution of these toxicants once an exposure event has occurred. However, if the toxicant is readily absorbed into the body, there are still other anatomical and physiological barriers that may prevent distribution to the target tissue to elicit a toxic response. As the toxicological response is often related to the exposed dose, interactions between the toxicant and the body s barriers and defense mechanisms will have an effect on toxicant movement in the body, and ultimately modulate the rate and extent of toxicant absorption and distribution to the target tissue. 

The study protocol must, first and foremost, contain a clearly stated objective of the research activity to follow. It has not been unusual for studies to be conducted without all of the study team understanding the scope of the Investigation. For example, a study conducted to determine the Identity and relative quantity of a pesticide and Its metabolites 1n the edible portions of food-producing animals should be restricted to the activities necessary to provide this Information. Without a clearly stated objective, this type of study could Instead be manipulated Into an attempt to determine toxicological responses or pathological effects. The data obtained could be of questionable value because the protocol design would not contain the necessary elements to provide reliable data. This 1s not to say that combined studies are of no value, but 1f a study 1s multidisciplinary 1n nature, the study design should contain Input from staff qualified 1n the disciplines Involved. 

A novel approach using the sorbent phase directly (with no extraction) in contact with cell lines from rainbow trout liver was developed by Schirmer et al.114 and Bopp et al.115 The cell lines were used to detect EROD activity from specific PAHs. A modified ceramic dosimeter (Toximeter sampler containing Biosilon 160-300 pm diameter polystyrene beads as the sorbent phase) was deployed for extended periods in groundwater known to be contaminated by PAHs. The response obtained using the cell lines incubated with Biosilon beads correlated with the concentrations of PAHs known to have EROD-inducing activity. The system is versatile as other cell lines can be used depending on the toxicological response of interest. 

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