Introduction Flashcards
what is toxiology
science of poisons (toxicants)
toxicology can be defined as
the science of toxicants, their physical and chemica properties, sources, biologic effects, mechanisms of action, clinical signs, lesions, analysis, diagnosis, differential diagonosis and treatment(or prevention) of diseases caused by toxicants
main aspects of clinical toxicology
diagnosis
treatment
T/F drugs can be poisons and poisons can be drugs
True
the dose is the difference
drugs and poisons are both
xenobiotics
foreign chemicals that the body does not produce
poison (toxicant)
any substance (solid, liquid, or gas) when applied or introduced into the body may interfere with life processes or biological functions
sources of poisons
natural (plant, animal, mineral, fungi or bacteria)
synthetic (organophostphates, insecticides, herbicides etc)
toxin (biotoxin)
poison from a biologic process
e.g. zootoxins or animal toxins, phytotoxins or plant toxins, bacterial toxins and mycotoxins
toxic
used to describe the deleterious or undesireable effects or poisons
toxicosis (poisoning or intoxication)
disease caused by exposure to a poison
toxicity
amount of a poison that under certain circumstances will cause toxic effects
toxicity is usually expressed as
mammals: LD50 in mg/kg of body weight
birds: LC50 (lethal concentration 50) in mg/kg feed
fish: LC50 in mg/liter water
acute toxicity
effect of single or multiple doses during a 24 hour period
subacute toxicity
effect prodiced by daily exposure from 1-30 days
subchronic toxicity
effect of exposure from 30-90 days
chronic toxicity
effect produced by daily exposure for a period of 3 months or more
chronicity factor
ratio between acute LD50 and chronic LD50
ex: warfarin: acute LD50 = 1.6, chronic LD50 = 0.077
1. 6/0.077 = 21.0
T/F counpounds with cumulative effect have a high chronicity factor
True
chronicity factor >2.0 indicates a relatively cumulative toxicant
toxicity values are influenced by
species, breed, individual, sex, age, dosage of poison, duration of exposure, and other factors
extremely toxic
1 mg/kg or less
highly toxic
>1-50 mg/kg
moderately toxic
> 50-500 mg/kg
slightly toxic
0.5-5 g/kg
practically nontoxic
>5-15 g/kg
relatively harmless
> 15 g/kg
highest nontoxic dose (HNTD)
highest or largest dose which does not result in undesirable or toxic alterations
maximum tolerated dose or minimal toxic dose (MTD)
similar to the highest nontoxic dose
toxic dose low (TDL)
lowest dose which prodices toxic alterations and administering twice this dose will not cause death
toxic dose high (TDH)
dose which produces toxic alterations and administering twice this dose will result in death
no-effect level (maximum nontoxic level)
amount of a chemical that can be ingested without causing any deaths, illness or toxic alterations in any of the animals for the stated period (usually 90 days to 2+ years depending on species)
lethal dose
dose that causes death in any animal during the peroid of observation
LD0
highest does that does not cause any death
LD50
the dose that kills 50% of animals in the group
LD 100
loest dose that kills all the animals in the group
hazard
danger from the possibility of exposure
T/F a poison may be highly toxic but not hazardous
True
risk ratio
calculated as the ratio between toxicity and use level
ex. urea: toxicity = 300mg/kg, use level = 100mg/kg; risk ratio= 3:1
monensin: toxicity = 20mg/kg, use level = 1mg/kg; risk ratio= 20:1
monensin is much more toxic than urea but the risk of urea toxicosis is much higher than monensin toxicosis
