Toxicity Testing

The following is FALSE on toxicology testing:

• Toxicology testing is performed by the registrant or its agents (consultants) and provided to the agencies for review.

• Experimental results can be influenced by choice of species or strain.

• Human responses can be mimicked exactly or modeled by a single animal species.

• Animals are used as human surrogates.

The following is TRUE on why animal tests were developed and used EXCEPT:

• Chemical exposure can be precisely controlled.

• Environmental conditions can be well-controlled.

• The mechanism by which toxicity occurs can be studied.

• Different strains of animals must be used to facilitate comparisons between new and existing chemicals.

The following is TRUE of acute toxicity test EXCEPT:

• Species - Hen preferred for oral and inhalation tests; zebrafish preferred for dermal tests

• Age – Young adults

• Dosages - Three dose levels recommended; exposures are single doses or fractionated doses up to 24 hours for oral and dermal studies and 4-hour exposure for inhalation studies.

• Number of animals - 5 of each sex per dose level

The following is NOT allergy assessment methods:

• Patch test

• Ames test

• Skin prick test

• Challenge test

The following match is FALSE of each description with its corresponding term:

• Single dose test …… acute test

• Skin irritation test … specific test

• 90 days test …… chronic test

• Carcinogenicity test …… short term test

The following is TRUE of in vitro tests for detecting gene mutations:

• Comet assay

• S9 incubations

• Micronucleus test

• Microarray test

The following is TRUE of in vitro testing:

• In vitro test alternatives for all in vivo end parameters will be available in the near future.

• The HGPRT test predicts genotoxicity for mammalian cells.

• In vitro toxicity testing is most useful for genotoxicity.

• The Mouse Lymphoma TK assay can predict DNA damage.

What is the most important principle underlying the investigation of the teratogenicity of chemical compounds for men by doing animal experiments?

• Susceptibility varies only marginally with the species investigated.

• There is homology in development for different mammalian species.

• Dose-response curves show the same characteristics in different mammalian species.

• Mechanisms of teratogenicity are similar in different mammalian species.

The following statement is FALSE of controls used in in vivo studies:

• Untreated control – control animals receiving same conditions, same diet minus the test substance.

• Vehicle control - control animals receiving vehicle (gelatin, corn oil, normal saline) minus the test substance.

• Positive control – control animals treated with a test substance also known to produce a specific effect.

• Self-control – control animals expected to give no response.

The following is TRUE of advantages using animals as human surrogates EXCEPT:

• Animals used are genetically similar and disease-free.

• Experiments using animals can be standardized by monitoring and controlling uncertainties and environmental factors.

• Animals have early sexual maturity, short gestation and large litters that facilitates multigenerational studies.

• Animals have a relatively long life span allowing lifetime exposures.