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16 Cards in this Set

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Definition of Toxicity.
The relative potency of a toxicant.

Usually toxicants are compared on a mg (of toxicant) / kg of body weight basis.
Definition of Toxicosis.
A pathologic condition that results from exposure to a toxicant. (poisoning=intoxication)
Definition of Dose.
Total amount of toxicant received by an animal.
Definition of Dosage.
Amount of toxicant per unit of animal weight.
Definition of Quantal Response.
Quantal response (population response)=a binary response, the effect happens or it does not happen
Definition of Graded Response.
Graded response (individual response)=the toxic effects become more severe as the dose increases
Definition of LD50.
Lethal Dose (LD) or Concentration (LC) LD50= dose likely to cause death in 50% of a given species/age/sex group under specified conditions
Definition of Therapeutic Ratio.
Therapeutic Index (Therapeutic Ratio) Ratio of LD50 to ED50 (units are %)
TI= LD50 \ ED50
Definition of Acute Toxicant Exposure.
Toxicity after single or multiple doses up to 24 hr following exposure
Definition of Sub-Chronic Toxicant Exposure.
Toxicity after 30 to 90 days of repeated or continuous exposure
Definition of Chronic Toxicant Exposure.
Toxicity over prolonged periods. 1 year for mice, 2 years for rats, 3 years for dogs (?)
Describe first order kinetics.
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
Describe zero order kinetics.
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
List some Toxicity factors that are associated with the Toxicant.
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)
List some Toxicity factors that are associated with the Host.
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
List some toxicity factors associated with the Environment.
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