Toxic dose level

Vapors of both benzal chloride and benzotrichloride are strongly irritating and lacrimatory. Reported toxicides appear in Table 3. Also, for benzotnchlonde, the lowest pubflshed lethal dose (frog) is 2150 mg/kg (69) and the toxic dose level (inhalation rats) is 125 ppm/4 h (69). 

Toxicity and Hazards. The odor cf ozone can be detected in concn as low as several parts per hundred million by vol (pphm). The threshold limit value (TLV) is O.lppmor 0.2mg/m3 its toxic dose level (TDL), 50% kill concn is 2ppm (Ref 6) Pure 100% liq ozone may be kept safely at 90°K (cooled by liq oxygen) for indefinite periods of time, but the smallest provocation, such as a spark or fast warming, even only up to bp (161°K), causes detonation. The evapn of liq ozone, for example, in the process of the prepn of pure gaseous ozone is, therefore, a dangerous procedure (Ref 3, p 224)... 

Treatment of rats with cypermethrin up to 8 mg/kg/day produced no malformations [140]. Maternally toxic dose level of bifenthrin did not produce adverse effects on embryonic development in rats [141], A rabbit teratology study with 30 or 90 mg/kg/day tetramethrin during fetal organogenesis demonstrated no adverse effects on skeletal or external development [137]. 

The trypsinized cultures are counted and a sample is assessed for survival as for the cytotoxicity assay. In addition, an appropriate number of cells are reseeded for estimation of mutation frequency at the day 8 expression time. The cells are transferred to roller bottles (usually 490 cm2) for this stage. The bottles are gassed with pure CO2, the tops are tightened and the bottles are incubated at 37°C on a roller machine (approximate speed 0.5-1.0 rev min-1). Usually 106 7 8 9 viable cells are reseeded in 50 ml of Eagle s medium containing serum, but more cells are required at the toxic dose levels. 

It is important to use different doses of a chemical or drug to evaluate chemical safety vis-a-vis skin toxicity. Dose levels to be tested for acute dermal toxicity in animals should be sufficient in number, (e.g., three or more and spaced appropriately to produce test groups with a range of toxic effects and mortality rates). The data should permit an acceptable determination of LD50. 

Phase I Initial Pharmacological Evaluation. Determines the safe dosage level for humans. The medication is given to volunteers at gradual doses. The first sign of toxicity is noted. Dosage levels below the toxic dose level are considered safe. 

Sitosterol 3-(5-D-glucoside Ficus religiosa 0/ Moraceae Bark It reportedly showed hypoglycemic activity in rabbits, which reached a maximum after 4 hours when the compound was administered orally at 25 mg/kg and after 2 hour when the compound was administered i.v. at 5 and 7.5 mg/kg. It produced CNS stimulation, convulsions and reversal of reserpine depression in mice at toxic dose levels. I.D50 was found to be 62 mg/ kg in mice [45],... 

The toxic dose levels of silver and silver compounds have been determined in animal toxicity studies (Sweet 1989). In mice, orally administered silver nitrate had an LD50 of 50 mg kg (the LD50 is the dose required to kill 50% of the test group), whilst silver sulfadiazene had an LD50 of 5000 mg kg. In occupational medicine, the MAK-value (maximum allowable concentration at the workplace) has been set at 0.1 mg m for metallic silver and 0.01 mg m for silver salts as Ag (DFG 2002). The same values were set as TLV (Threshold Limit Values) in the USA (ACGIH 2002). 

Thorium nitrate [Th(N03)4.4H20] was used, together with Mg powd, in early illuminating flashes for photography it was also patented for use in a pyrot flare formulation (Ref 4, pp 115 340). Ref 7 states that contact of Th nitrate with easily oxidizable substances may easily flash or cause violent combustion or expln. In addition, toxic nitrogen oxide gas is generated in the event of a fire. Its toxic dose level (TDL) is LDjo abd-rat, 68mg/kg... 

Its centrally potent actions are used in various conditions, namely postencephphalitic parkinsonism, paralysis agitans, respiratory stimulation, some types of spastic and rigid states and rarely in schizophrenia at its toxic dose level). 

Conversely the least concern might be attributed to a chemical which, after multiple species tests, is found to only enhance the incidence of common tumors, in one site, in one sex and species, and only following long exposure at high and toxic dose levels. 

Experiences gained by such studies have often shown wide differences in toxic dose levels from species to species. These variations are usually attributed to two major (and overlapping) causes variations in enzyme systems which result in different metabolic transformation (or in wide variations in the rates of such transformations), and species variations in pharmacokinetic properties such as rates of absorption, distribution, and elimination of the drug or its metabolites. 

Porfiromycin (LXVc), the iV-methyl analogue of mitomycin C, is also a metabolite of Streptomyces verticillatus and has a wide spectrum antitumour activity [300]. It has a therapeutic index of ten against Walker 256, and two against L 1210. In mice it has a LD50 value of 44 mg/kg (i.p.), and in rats 68 mg/kg (oral), which are about four times that of mitomycin C. It has a lower antitumour activity than mitomycin C at comparable toxic dose levels except for ascitic forms of Ehrlich carcinoma in mice [300, 301]. 

Toxicity is usually expressed as an LD50 value and is typically expressed in mg of material per kg of subject-body weight. The LD50 values are usually derived from populations of mice and then extrapolated in humans to calculate the toxic dose levels. A toxin with an LD50 of <0.025 xg/kg is regarded as being among the... 

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