Variables of toxic effects

Long-Term Effects Etiologic Effects Variables of Toxic Effects Dose/Response Susceptible Target Organs Exposure Rate... 

The results demonstrated a wide range of toxic effects and loadings for textile effluents (Tab. 13). Inter-effluent toxicity differences could be attributed to factors such as type of industrial process, degree of waste treatment, variability of effluent composition and dilution by process waters. Toxic loads from industries 9 and 10 indicate they contribute the greatest toxic load to the receiving waters therefore based on PEEP results the first priority would be to reduce the toxic loading from industries 9 and 10. 

In vivo toxicity tests involve the direct exposure (via appropriate exposure routes) of hving animals to variable doses of toxins over time, followed by measurement of toxic effects or exposure indicators. Inhalation tests either expose the subject animals to known concentrations of particles in an airstream, or utihze direct intratracheal implantation of the particles in the subject animals (e.g., studies summarized in Johnson and... 

In many cases, at least for screening purposes and for preliminary comparisons of several compounds, approximate information on the intrinsic stability of a molecule, taken as an index of persistence potential that is independent of environmental variables, can be useful. In these cases the use of predictive approaches based on the molecular properties and structure (QSAR quantitative structure-activity relationships) could be very helpful in the absence of experimental information. Although the application of QSARs for the prediction of persistence has not yet been developed for screening as it has for other ecotoxicological aspects (e.g. prediction of toxic effects or bioaccumulation), in the last few years there has been some promising progress (Tremolada et al, 1991 Vasseur etal., 1993 Macalady and Schwarzenbach, 1993). 

E. Ganciclovir. All toxic reports have been after intravenous administration. The doses producing toxic effects after high chronic or inadvertent acute IV overdose have been variable. No toxic effects were noted in two adults who were given 3.5 g and 11 mg/kg for 7 doses over 3 days, respectively. However, single doses of 25 mg/kg and 6 g, or daily doses of 8 m g for 4 days or 3 g for 2 days, resulted in neutropenia, granulocytopenia, pancytopenia, and/or thrombocyctopenia. An adult and a 2-kg infant developed hepatitis after 10 mg/kg and 40-mg doses, respectively. An adult developed seizures after a 9-mg/kg dose, and others have had increased serum creatinine levels after 5-to 7-g doses. 

Animal experiments are usually done on groups of rats or mice, but other species are also used. The variability in toxic effect (concentration and time) between animal species can be substantial. No definitive correlation is available to relate hiunan and animal responses, for example, the relationship between species often depends on the substance to which the relevant species are exposed substance specific conversion models are sometimes required. Therefore, species-specific methods need to be defined for converting animal data to human effects or for using animal data directly. Anderson (1983) suggests that an equiv-... 

The classic description of histamine s pharmacological action consists of the triple reaction of Lewis, which has not yet received an incontrovertible explanation. The most striking feature is the variability of the effects of exogenous histamine in different species. The guinea-pig is asphyxiated from bronchoconstriction, the dog dies in circulatory collapse with constriction of the supra-hepatic veins, the cat dies in a state of abrupt hypotension, while the rabbit dies of a right-heart failure following constriction of the pulmonary arterioles. The toxicity of histamine... 

Laboratory experiments using rodents, or the use of gas analysis, tend to be confused by the dominant variable of fuel—air ratio as well as important effects of burning configuration, heat input, equipment design, and toxicity criteria used, ie, death vs incapacitation, time to death, lethal concentration, etc (154,155). Some comparisons of polyurethane foam combustion toxicity with and without phosphoms flame retardants show no consistent positive or negative effect. Moreover, data from small-scale tests have doubtful relevance to real fine ha2ards. 

The quantitative measurement of toxicity level is expressed by parameters like NOEL (no observed effect level), NOAEL (no observed adverse effect level), and ADI (acceptable daily intake). The NOEL values are divided by 100 to obtain ADI values. The 100 safety factor derives from 10 x 10, where the 10s represent the animal-to-human conversion rate and the human variability factor. Currently, the most useful index of safety is the ADI, expressed as milligrams of test substance per kilogram of body weight (ppm), with the recommendation not to eat more than the ADI per day. The FDA, EU, and WHO agree on the ADI principle. 

Monsanto. 1978. TSCA sect. 8(d) submission 40-7859047. A study of variables effecting the river die-away test. Special study 1978. Washington, D.C. Office of Toxic Substances, U.S. Environmental Protection Agency. EPA Doc Control No. OTS 84003A... 

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