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Flashcards in toxicology Deck (29)
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1
Q

What trends do we see in chemical production in the USA?

A

increase in chemical production

2
Q

toxicology

A

the study of the adverse effects of chemical, physical or biological agents on living organisms and the ecosystem, including the prevention and amelioration of such adverse effects.

3
Q

chemical hazard regulations

A

The Toxic Substances Control Act of 1976

4
Q

The Toxic Substances Control Act of 1976

A

authorized the EPA to both assess new chemicals before they enter the marketplace and to review chemicals already on the market.

When the law was enacted, thousands of chemicals already being used were grandfathered in and accepted as just being okay in commerce

EPA has taken actions to regulate exposure to about 3,500 of 32,000 new HPV (High Production Volume - >1,000,000 pounds produced each year) chemicals submitted for review since TSCA was enacted

5
Q

Xenobiotic

A

chemical substances foreign to the biologic system. Incl natural occurring substances, drugs, etc.

6
Q

toxin

A

a toxic substance made by living organisms

7
Q

toxicant

A

toxic substances that are man made

8
Q

Goal of toxicology

A

To understand the causal relationships between toxicant exposure and adverse human health effects

9
Q

Experimental Methods of toxicology

A

Highly controlled experiments, usually in a laboratory setting, typically using animals

10
Q

Epidemiological Methods of toxicology

A

Observations on uncontrolled populations, usually in the natural environment

11
Q

toxicology basic understanding:

A

Even innocuous (non-harmful) substances can become toxic in high doses

High O2 can lead to O2 intoxication

Too much water can cause osmotic imbalance or brain damage

12
Q

Dose-response relationship

A

Type of correlative relationship between “the characteristics of exposure to a chemical and the spectrum of effects caused by the chemical”

13
Q

Dose-response Curve

A

type of graph

Used to describe the effect of exposure to a chemical or toxic substance upon an organism such as an experimental animal

Different curves used for individuals v populations

14
Q

how do we measure toxicity

A

The classical measure of acute toxicity is the LD50

LD50: Lethal dose that kills 50% of the study population.
Dosage is measured in weight of toxicant per body weight of subject, often as mg toxicant/kg body weight.

Drug action is measured by the ED50

ED50: Effective dose that produces the desired effect in 50% of the population.

15
Q

problem with animal studies

A

Does Not stimulate the real world
What we learn is very specific
Does give us some ideas, inclinations, and directions to follow in the future studies
Usually high dose exposure requiring extrapolation

16
Q

acute toxicity

A

single exposure to a toxicant
poisoning
usually life threatening effect
diagnoses and treatments or antidotes available

17
Q

subacute/chronic toxcity

A

prolonged exposure to a toxicant
no immediate effect but could be life-threatening in the long term
organ system effects and cancer are endpoints
usually difficult to diagnose and treat
difficult to distinguish from other influences

18
Q

risk assessment paradigm

A

Hazard assessment
Exposure assessment
Risk assessment
Risk Management

19
Q

Hazard assessment

A

animal studies

20
Q

Exposure assessment

A

field studies

21
Q

Risk assessment

A

hazard x exposure, extrapolation to humans, safety factors

22
Q

Risk Management

A

depends on context, risk-benefit analysis

23
Q

what we know about chemical mixtures

A

We are not exposed to things in a vacuum

Most difficult challenge yet, most common situation

24
Q

3 joint interactions of chemical mixtures

A

antagonism
additivity
synergism

25
Q

antagonism chemical mixtures

A

response is less than expected
physiological –> severe drop in blood pressure resulting from barbituate overdose can be reversed by administering vasopressors

chemical –> reduce mercury toxicity by chelating ions with dimercaprol

disposition –> swallowed poison is absorbed by charcol in the stomach

receptor –> carbon monoxide poisoning is treated with oxygen to displace carbon monoxide hemoglobin receptors

26
Q

additivity chemical mixtures

A

the response as expected

dose(exposure) and response (effect)

27
Q

synergism chemical mixtures

A

the response is greater than expected

cosynergism –> two agents enhance the toxicity of each other

potentiation –> only one agent affects the toxicity of the other with no toxicity itself

coalitive –> two agents with no observable toxicity effect

28
Q

individual dose-response graph

A

demonstrates the response to a chemical as exposure increases –> assumes a one time exposure and a graded increasing response as a dose of the substance increases

29
Q

population dose-response graph

A

demonstrated observed outcomes in a population –> the relationship of observed responses or outcomes in a population to varying levels of beneficial or harmful agents