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33 Cards in this Set
- Front
- Back
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Poison
-defintion |
-substance that causes dose related adverse health effects at relatively small doses
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Toxicant
-definition |
-poison
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Toxin
-defintion |
-a poison of biological origin
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Toxicity
-definition |
-characterization of the potency and toxic effects associated with a poison
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Toxicosis
-definition |
-a disease/syndrome caused by a poison
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How does poisoning occur?
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-Exposure to a poison
-poison reaches tissues (tissue dose) -biological interaction that disrupts normal biological function -with higher doses, there are earlier cellular changes but the cells can return to normal biological function through adaptive stress responses -with even higher doses cell injury occurs resulting in morbidity and mortality |
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Toxicological Risk
-definition |
-what is the probability that an organism or population will suffer from an adverse effect
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Critical risk area
-defintion |
-vulnerable subpopulation to the hazard that gets exposed to the hazard
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Why is contact between the receptor population and the hazard important in toxicology?
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-if the receptor population and the hazard are not in contact, then there is no risk
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Central Concept of Toxicology
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-threshold-model
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NOAEL
-defintion |
-No Observable Adverse Effect Level
-able to assume that if an animal is exposed to a toxin below the level of NOAEL, there will be no adverse effects |
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LOAEL
-definition |
-Lowest Observable Adverse Effect Level
-some uncertainty as to what the dose is where the animal may get poisoned |
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Why do you need to be careful when interpreting the LD50?
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-it does not account for animals that were debilitated by poisoning but didn't die
-data isn't necessarily for the same route of exposure or species -No information concerning the slope or NOAEL (don't know at what level animals started having problems) |
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Model followed by carcinogen/radiation exposure?
-what does it mean? |
-linear model (non-threshold)
-induction can follow a single mutation event due to a single chemical-DNA interaction in a single cell that only requires one molecule/particle of a mutagen -with every exposure there is some increase in mutagenic exposure -there is no safe dose |
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Hormesis
-definition |
-a low dose response opposite to a high dose response
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Hormesis
-typically seen with |
-vitamins
-trace elements |
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-hormesis
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Hysteresis
-definition |
-a disconnect between stimulus/dose and effect over time
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Hysteresis
-can be due to |
-adaptive processes (increased ability to deal with the poison after the first dose)
-inability for an animal to adapt to a toxicant (liver failure) |
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-hysteresis
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Physical-Chemical properties associated with a toxin
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-environmental distribution
-persistence -biological activity |
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Can toxicity be based on physical-chemical properties?
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-some success with QSAR (Quantitative Structure Activity Relationship) but it can't be relied on to base a risk assessment off of
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QSAR
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-Quantitative Structure Activity Relationship
-define values based on chemical parameters and try to create an algorithm to predict what the toxicity will be |
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Mixture effects
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Alterations to the physical-chemical profile:
-chemical interactions -pharmacokinetic interactions -pharmacodynamic interactions |
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Chemical interactions due to mixture effects
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-precipitation
-chemical reaction (forms new compounds that may be more or less toxic) |
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Pharmacokinetic interactions due to mixture effects
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-change in rate of absorption (important w/ nutrient minerals)
-enzyme induction/suppression (CYT p450) |
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Pharmacodynamic interactions due to mixture effects
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-cumulative responses
-synergism -antagonism |
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Main points of concern for veterinarians in clinical toxicology
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-diagnosis
-treatment -prevention |
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Key questions to ask when making a diagnosis
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-what physical evidence of poison is available
-how could exposure have occurred -what syndromes are expected vs. observed -what tests are available to prove exposure/confirm poisoning |
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Tips for making a diagnosis
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-common things occur commonly
-get the big picture -use all of your senses -consider things that you may not see -consider changes over time -relate the current syndrome to possible mechanisms |
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Important steps to take in toxic lawyering
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-invest in and use a camera
-take as many samples as soon as possible to minimize the chain of custody -take all reasonable steps to confirm a diagnosis (multiple lines of evidence; accredited diagnostic services) |
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Steps to take in Treatment
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DOS:
-decontaminate -oppose -support |
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Toxin prevention
-steps |
-remove source or remove from source of exposure
-avoid vulnerable conditions |
