Lethality equivalent

When the sterilization process temperature deviates from 121°C, the amount of time providing equivalent lethality can be determined by the following formula ... 

The exponential relationship between numbers of surviving microorganisms and lime of exposure at a particular temperature parallels first-order chemical kinetics. In these circumstances it should follow that equivalent lethalities at different temperatures of exposure should be predictable. When D-values have been determined for pure cultures of the same microorganism at different temperatures (Fig. 3), it has been shown that there is a linear relationship between the logarithm of the D-values and the temperatures at which they were determined (T, T-2, Ty etc). The term z is given to the slope of this line z is the number of degrees of temperature change necessary to alter the value of O by a... 

The move away from compendial cycles to overkill and SAL cycles w-ent hand in hand with an increasing interest in the concept of equivalent lethalities being obtainable from different temperature/time combinations—the Fq concept. 

At one time, the pharmacopoeias were specifying a standard Fq value of 8 min for steam sterilization regardless of load type, inesterilizaiion microbiological contamiiuition levels, or product stability. The last editions of the major pharmacopoeias in which an appeared were the 1980 USP andi the 1988 BP. An Fq of 8 means that the sterilizing cycle being used has an equivalent lethality to 8 min at 12rc. 

The Parenteral Drug Association equation, Eq. (4.5), for calculating equivalent lethalities is... 

The F-value concept which was developed for steam sterilization processes has an equivalent in dry heat sterilization although its application has been limited. The Fh designation describes the lethality of a dry heat process in terms of the equivalent number of minutes exposure at 170°C, and in this case a z value of 20°C has been found empirically to be appropriate for calculation purposes this contrast with the value of 10°C which is typically employed to describe moist heat resistance. 

Intake can be expressed either as a pollutant mass per unit time, as discussed above, or as a mass per kg of body weight per unit time. The latter expression facilitates comparison to health effects data, especially laboratory animal data, which are commonly reported in equivalent units. Similarly, depending on the route of exposure, intake may be estimated on an annual basis to address chronic effects, or on a smaller time scale for addressing acute effects including lethality, teratogenesis, reproductive and neurotoxic effects. 

Copper is lethal to mammals through a variety of routes (Table 3.7). Single oral doses of 6 to 637 mg Cu/kg BW are fatal to humans. A single oral dose of 200 mg/kg BW is usually fatal to cattle. Dietary copper is lethal when eaten for extended periods at more than 80 mg Cu/kg ration in sheep (equivalent to 5.1 to 10.7 mg Cu/kg BW daily), more than 238 mg/kg ration in pigs, and more than 4000 mg/kg ration in rats (equivalent to more than 133 mg Cu/kg BW daily Table 3.7). 

HUMANS, Homo sapiens 100 pg/L 25-50 mg/kg BW 100 mg/kg BW Suicidal female swallowed 6 g chlordane, equivalent to 104 mg/kg BW Reduced growth and altered cell morphology in human cell cultures (USEPA 1980) Acute lethal oral dose (WHO 1984) Fatal (IARC 1979) Death in 9 days (WHO 1984)... 

Sodium arsenite (used to Lethal dose of 923-2770 mg equivalent to about 34 mg/kg BW ... 

Ralls, K., Ballou, J.D. and Templeton, A. (1988) Estimates of lethal equivalents and the cost of inbreeding in mammals. Conserv. Biol. 2, 185-193. 

Phytosterol dealkylation can be harnessed in insects to release a fluoroacetate equivalent from a 29-fluorinated sterol. Moreover, the fluorocitrate which then results from the "lethal synthesis" can be isolated and chemically characterized. hope that the range of insects susceptible to the 29-fluorophytosterols and more commercially viable analogs will be further explored. Furthermore, we urge wider scrutiny of insect biochemical pathways in search of possible targets for suicide substrates or latent toxin release. 

The toxic effect produced by a chemical agent on a susceptible organism depends on the nature and magnitude of its interactions with the vital processes which it disrupts (which may be termed its intrinsic toxicity) and on the amounts which reach the sites of interaction. Both these determinants of toxic effect are expressions of biophysical and physico-chemical factors. The effectiveness of the lethal interaction which is equivalent to the intrinsic toxicity... 

Preparative Plates Were Spotted With Amounts of Crude Material Equivalent to the 100% Lethal s Determined in LD q Studies. Solvent Systems Used Were (A) CHCI3 CH3OH (6N)NH40H (90 9.5 0.5) and (B) CHCl3 CH30H H20 (60 35 8). 

FIG. 1. Douhletime mutations. The sequence of DBT and its mutations are shown. The DBT kinase domain (residues 1—292) was deduced by comparison to CKl (Gross Anderson, 1998). The kinase sub-domains are given in roman numerals, and dbfi mutants map to the catalytic domain, dco and dco are embryonic lethal mutations, dco is a pupal lethal associated with overgrowth of imaginal discs (Zilian et al 1999). The tau mutation, which arose in the Syrian hamster, affects the residue equivalent to 178 of DBT as shown. 

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