toxicology

Question 1

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

Answer 1

increase in chemical production

Question 2

toxicology

Answer 2

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.

Question 3

chemical hazard regulations

Answer 3

The Toxic Substances Control Act of 1976

Question 4

The Toxic Substances Control Act of 1976

Answer 4

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

Question 5

Xenobiotic

Answer 5

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

Question 6

toxin

Answer 6

a toxic substance made by living organisms

Question 7

toxicant

Answer 7

toxic substances that are man made

Question 8

Goal of toxicology

Answer 8

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

Question 9

Experimental Methods of toxicology

Answer 9

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

Question 10

Epidemiological Methods of toxicology

Answer 10

Observations on uncontrolled populations, usually in the natural environment

Question 11

toxicology basic understanding:

Answer 11

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

Question 12

Dose-response relationship

Answer 12

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

Question 13

Dose-response Curve

Answer 13

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

Question 14

how do we measure toxicity

Answer 14

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.

Question 15

problem with animal studies

Answer 15

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

Question 16

acute toxicity

Answer 16

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

Question 17

subacute/chronic toxcity

Answer 17

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

Question 18

risk assessment paradigm

Answer 18

Hazard assessment
Exposure assessment
Risk assessment
Risk Management

Question 19

Hazard assessment

Answer 19

animal studies

Question 20

Exposure assessment

Answer 20

field studies

Question 21

Risk assessment

Answer 21

hazard x exposure, extrapolation to humans, safety factors

Question 22

Risk Management

Answer 22

depends on context, risk-benefit analysis

Question 23

what we know about chemical mixtures

Answer 23

We are not exposed to things in a vacuum

Most difficult challenge yet, most common situation

Question 24

3 joint interactions of chemical mixtures

Answer 24

antagonism
additivity
synergism

Question 25

antagonism chemical mixtures

Answer 25

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

Question 26

additivity chemical mixtures

Answer 26

the response as expected

dose(exposure) and response (effect)

Question 27

synergism chemical mixtures

Answer 27

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

Question 28

individual dose-response graph

Answer 28

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

Question 29

population dose-response graph

Answer 29

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