Toxicology

Question 1

Toxic effect criteria

Answer 1

Measurable or observable physiological change.
Duplicated from animal to animal.
Changed normal physiology which impairs a protective mechanism.
Reversible or attenuated when stimulus is removed.
Effect doesn’t occur without a stimulus.
Observation reproducible.
Change reduces efficiency of an organ or function and impairs physiological reserve that interferes with ability to resist or adapt to other normal stimuli.

Question 2

Routes of entry

Answer 2

Inhalation, Ingestion, skin absorption and injection.

Question 3

Inhalation amount of toxic compounds dependent on

Answer 3

concentration, duration or exposure and pulmonary ventilation volumes.

Question 4

Factors affecting rate of skin absorption

Answer 4

Anatomical region, temperature, condition of skin (any abrasions).

Question 5

Dose-response relationship

Answer 5

The relationship of health related effects to the dose administered or exposed to.

Question 6

Dose response relationship formula

Answer 6

Concentration (C) x Time (T) = Constant (K)

Question 7

Threshold effect

Answer 7

The lowest dose at which a measurable effect is observed.

Question 8

Acute, Prolonged and Chronic Toxicity tests

Answer 8

Acute <24hrs
Prolonged 2, 4 or6 weeks
Chronic >3 months

Question 9

Central nervous system depressants.

Answer 9

CNSD - anesthesia. Headache, dizziness, lack of coordination, confusion. Can lead to death. In life aliphatic alcohols, aliphatic ketones, aromatic hydrocarbons, ethers, halogenated hydrocarbons.

Question 10

Carcinogenesis

Answer 10

Substance that will induce a malignant tumor in humans. 80 - 90% caused by environmental factors.

Question 11

Mutagenesis

Answer 11

Agent that affects the genetic material of the exposed organism. May cause cancer, birth defects, etc in later generations.

Question 12

Teratogenesis

Answer 12

Congenital malformation resulting from the interference with normal embryonic development by a chemical, biological or physical agent.

Question 13

Examples of teratogens

Answer 13

Metals, infections (i.e. Rubella), PCB, ionizing radiation, antineoplastic / alkylating agents

Question 14

Types of epidemiological studies

Answer 14

Descriptive studies - ID change in prevalence of disease in sub populations.
Retrospective studies - relationship between substance and effect caused by exposure that occurred months or years before the initiation of data collection.
Prospective studies - define more precisely the time relationship and magnitude of risk. Present and future continuing studies that measure health effects as they occur.

Question 15

Synergistic or potentiating effects

Answer 15

Combined risk of illness from the exposure of two different agents which far exceeds the sum of their individual risks (i.e. Smoking and asbestos).

Question 16

Hydrogen cyanide toxicity

Answer 16

Chemical asphyxiant that inhibits enzyme systems, cytochrome oxydase, necessary for cellular oxygen use.