Toxicity, threshold

Use of dry chemical, alcohol foam, or carbon dioxide is recommended for cycloahphatic amine fire fighting. Water spray is recommended only to flush spills away to prevent exposures. In the aquatic environment, cyclohexylamine has a high (420 mg/L) toxicity threshold for bacteria (Pseudomonasputida) (68), and is considered biodegradable, that is, rnineralizable to CO2 and H2O, by acclimatized bacteria. 

Cook DL, Atkins WM. Enhanced detoxication due to distributive catalysis and toxic thresholds a kinetic analysis. Biochemistry 1997 36 10802-6. 

Physical methods for the control of microbial biofilms, although often effective, are in many situations impractical. In this context it is notable that an almost universal feature of the biofilm mode of growth is their profound resistance to antibacterial compounds. Conventional chemical control methods, developed for use against fastgrowing planktonic cultures are only poorly effective against biofilm bacteria. Large doses of biocide or antibiotics, which are either environmentally undesirable or above toxic thresholds respectively, are required to eradicate biofilms in industry and medicine. 

Nonpregnant ewes given 6 mg Pb/kg BW daily Toxic threshold 4... 

In aquatic environments, Spear (1981) spotlights three research needs (1) development of analytical procedures for measurement of individual dissolved zinc species, notably the aquo ion and zinc chloride, and for nondissolved species that occur in natural waters (2) separation of natural from anthropogenic influences of sediment-water interactions on flux rates, with emphasis on anoxic conditions, the role of microorganisms, and the stability of organozinc complexes and (3) establishment of toxicity thresholds for aquatic organisms based on bioaccumulation and survival to determine the critical dose and the critical dose rate, with emphasis on aquatic communities inhabiting locales where zinc is deposited in sediments. These research needs are still valid. 

Current research needs include the development of protocols to (1) separate, quantitate, and verify the different chemical species of zinc (2) identify natural from anthropogenic sources of zinc (3) establish toxicity thresholds based on accumulation (4) evaluate the significance of tissue concentrations in target organs as indicators of zinc stress and (5) measure the long term consequences of zinc interactions with other nutrients using animals of various age and nutrient status. 

Peterson, J.A. and A.V. Nebeker. 1992. Estimation of waterborne selenium concentrations that are toxicity thresholds for wildlife. Arch. Environ. Contamin. Toxicol. 23 154-162. 

LOAEL), and the highest dose at which no effects are observed, the no adverse effect level (NOAEL). In the interest of prudence, the NOAEL is generally considered as a conservative estimate of the toxicity threshold. 

Bringmann. G. and Ktihn. G. Comparison of the toxicity thresholds of water pollntants to bacteria, algae and protozoa in the cell multiplication inhibition test. Water Res., 14(3) 231-241. 1980. 

For these reasons, TDM can serve several roles when using clomipramine. First, it can be used to determine whether clomipramine or its demethlylated metabolite constitutes the majority of the circulating drug. Second, TDM can be used to guide dose adjustment to ensure plasma concentrations equivalent to those seen in adults whose OCD is successfully treated. This approach also ensures that concentration levels do not approach or exceed the toxic threshold for TCAs (i.e., greater than 450 ng/mL). Like adults, children and adolescents demonstrate a wide variability in their capacity to metabolize TCAs. As mentioned earlier, children are usually faster metabolizers of these drugs than adults, so they typically need doses of approximately 2.5 to 3.5 mg/kg. Once puberty has been reached, the required doses can be reduced by as much as 50%. 

In chemical toxicology, since it has been long known that the acute toxic threshold (LDjo) of a chemical is approximately the same in different species if the dose is expressed as a finction of body weight, this fraction has become the conventional unit in which to express the doses of different chemicals (Dedrick, 1973). The relationship is not precise, however for some chemicals, the LD50 values, even when expressed in these units, can differ by orders of magnitude. 

Bromocriptine and the ergot analogues suppress prolactin activity and amiodarone can cause iodine-induced hypo- or hyperthyroidism. Lithium, which has a low toxicity threshold, passes freely into milk and significant plasma concentrations may occur in nursing infants. 

Important to the determination of risk is the threshold dose of a toxicant. Threshold is the amount of a material below which you will see no toxic effect. See Figure 19. For most drugs and some pollutants there are lower limits to the... 

Thus, the inhibition of cholinesterase enzymes by organophosphorus compounds may last for several days or weeks, and repeated dosing at shorter intervals than the half-life of regeneration of the enzyme leads to accumulation of the inhibition until the toxic threshold of around 50% is reached. 

CA 86, 51210 (1977) [The toxic effect of PVC combstn products on the human organism was evaluated and the Toxic Threshold Level is reported as 0.3g of PVC products/M3 of air] 2) M. Bert et al, Reduction of Smoke Generation in Poly (Vinyl Chloride) Combustion , FireRes (4-5), 301-11 (1978) CA 90,72796 (1979) [The authors report that the most efficient (toxic) smoke suppressors for PVC are those which show catalytic activity in oxidation reactions, such as Cu, Fe, or V compds. These suppressors cause incandescence and complete combstn of the solid residue without excessive smoke prodn. They conclude that their efficiency is not very dependent on the anion bound to the metal, but may depend on the temp] 3) E A. Harrison, Toxicity of Vinyl... 

According to Sax (Ref 5) the toxic threshold level of the trisulfide vap, which is primarily H2S, is 15mg/m3 of air. Exposure to 800— lOOOppm of the vap in 30 mins may be fatal. Exposure to a v high concn of the vap (H2S) results in immediate death. The vap is av strong irritant to the mucous membranes (Ref 3). The liq trisulfide forms a caustic (Na2S) when in contact with the skin because of the alkali present in moist skin. This explains the strong irritant action of both the liq and vap (Refs 2,... 

It is possible that a toxicity threshold is not achieved at lower severities, reducing the inhibition from these conditions. The corn stover samples were consistently less inhibitory than the aspen wood samples. This is likely owing to the fact that fewer acids are inherent in the corn stover biomass than in the aspen wood biomass. For example, it was found that the pH of the corn stover hydrolysates was higher than the pH of aspen hydrolysates. Further testing is warranted to investigate the difference in the inhibition of the substrates and also to determine whether scatter is to blame for the appearance of a difference between pretreatments with and without carbonic acid when assessing the percent inhibition from Fig. 3. Pretreatment severity showed a marked effect on the degree of inhibition suffered by yeast cultures, but the presence or absence of carbonic acid appears to have had no influence on inhibition. Between the aspen wood and corn stover samples, there appeared to be a difference in inhibition rates. 

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