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16 Cards in this Set
- Front
- Back
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Definition of Toxicity.
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The relative potency of a toxicant.
Usually toxicants are compared on a mg (of toxicant) / kg of body weight basis. |
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Definition of Toxicosis.
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A pathologic condition that results from exposure to a toxicant. (poisoning=intoxication)
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Definition of Dose.
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Total amount of toxicant received by an animal.
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Definition of Dosage.
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Amount of toxicant per unit of animal weight.
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Definition of Quantal Response.
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Quantal response (population response)=a binary response, the effect happens or it does not happen
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Definition of Graded Response.
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Graded response (individual response)=the toxic effects become more severe as the dose increases
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Definition of LD50.
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Lethal Dose (LD) or Concentration (LC) LD50= dose likely to cause death in 50% of a given species/age/sex group under specified conditions
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Definition of Therapeutic Ratio.
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Therapeutic Index (Therapeutic Ratio) Ratio of LD50 to ED50 (units are %)
TI= LD50 \ ED50 |
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Definition of Acute Toxicant Exposure.
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Toxicity after single or multiple doses up to 24 hr following exposure
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Definition of Sub-Chronic Toxicant Exposure.
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Toxicity after 30 to 90 days of repeated or continuous exposure
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Definition of Chronic Toxicant Exposure.
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Toxicity over prolonged periods. 1 year for mice, 2 years for rats, 3 years for dogs (?)
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Describe first order kinetics.
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Most common reaction
Rate= k[A]^m M=1 for first order, therefore, rate is directly proportional to [A] Half life calculated as: t1/2 = 0.693 / k Rule of thumb: 10 half lives will virtually eliminate toxicant from body |
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Describe zero order kinetics.
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Saturated process proceeding at maximum amount the body can handle per unit time
Rate= k[A]m M=0 for zero order, therefore, any [A] = 1 (because any number to the zero exponent=1) and the reaction rate is independent of [A] Kinetics may change to first order after process is no longer saturated |
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List some Toxicity factors that are associated with the Toxicant.
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Solubility, Polarity, and Ionization
Vehicle and Formulation Effects: Water, propylene glycol, colloids Mixing/settling of powders and emulsions Impurities-dioxin contamination of 2,4,5-T Chemical Interactions Chemical combinations can form insoluble precipitates (e.g, sodium sulfate and lead) |
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List some Toxicity factors that are associated with the Host.
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Biotransformation and Bioactivation
Phase I-oxidation, reduction, hydrolysis Phase II-conjugation with endogenous molecules Influenced by: Parenchymal organ disease Toxicant localization in tissues with little PI/ PII activity Age and metabolic activity Species-specific variation, individual variation Gender and hormone differences |
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List some toxicity factors associated with the Environment.
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Season: ethylene glycol
Temperature:influence metabolism, food and water intake Light factors: biological rhythms influence susceptibility Housing: crowding, stress, ability to get away from a toxicant Construction materials: lead, formaldehyde Heating systems: malfunctions may release carbon monoxide Air circulation: ammonia gas Bedding: black walnut shavings > laminitis in horses |
