Document bRa26gB8JqzXpZo5zwYJ5596

TABLE 42-A COMBINED TABULATION OF TOXICITY CLASSES Commonly Used Term LDW Single Oral Dose for Bats (gmlkg) 4-hr Vapor Exposure Causing 2 to 4 Deaths tn 6-Rat Group (ppm) LD$o Skin for Rabbits (gmlkg) Probable Lethal Dose for Man Extremely toxic Highly toxic Moderately toxic Slightly toxic Practically nontoxic Relatively harmless 0 001 or less 0 001 to 0 05 0 05 to 0 5 0 5 to 5 0 5 0 to 15 0 More than 15 0 Less than 10 10 to 100 100 to 1,000 1,000 to 10,000 10,000 to 100,000 More than 100,000 0 005 or less 0 005 to 0 043 0 044 to 0 340 0 35 to 2 81 2 82 to 22 6 More than 22 6 Taste (1 grain) 1 tsp (4cc) 1 02 (30 gm) 1 pint (250 gm) 1 quart More than 1 quart Fwm Handbook of Toxcolog>, Vo/ J, Acute Toxictties ' W S Spector,ed Philadelphia, 1956 W B Sounder* Co axioms form the basis for experimental tox icology Although they appear self evident they are not susceptible to rigid proof 1 Any substance contacting or entering the body will be injurious at some degree of exposure and will be tolerated without effect at some lower exposure 2 The nature of the injuries which may de velop in men can be determined by the study of the reactions of experimental animals 3 It is possible to define an exposure to animals that has no effect upon its health Health and well-being, however, are not measurable It is the injury that is meas ured 4 From animal experiments, the degree of exposure that will not affect humans can be determined Experimental toxicology has done well for human safety by allowing regulation of ex posure m accord with the results of animal experiments The first attempts in estimating the toxicity of a substance are usually made on the basis of animal experiments Data from these ex periments is expressed as lethal doses (LD) in milligrams of substance per kilogram of body weight of the test animal The most commonly used expressions are these 1 MLD -- minimum lethal dose, the smallest dose which kills one of a group of test animals 2 LDm-- lethal dose for 50 per cent, the dose which kills one-half of a group of test ani mals (usually 10 or more) 3 LD,oo--lethal dose for 100 per cent, the dose which kills all of a group of test ani mals (usually 10 or more) These doses may also be expressed as lethal concentrations (LC) for airborne toxic substances Substances can then be rated according to their relative toxicity as shown in animal ex periments, and the probable lethal dose for humans can be estimated (See Table 42-A These ratings are based on the results of 1305