COVID-19 is an emerging, rapidly evolving situation.

Get the latest public health information from CDC and research information from NIH.

U.S. flag

An official website of the United States government

Dot gov

The .gov means it's official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Share This:
Study Information
Study Attribute Value
CEBS Accession Number: 002-01694-0003-0000-5
Chemical Name: Benzidine dihydrochloride
CASRN: 531-85-1
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 445801_SCE
Study Result: Positive

Study Result: Positive
Activation Trial Trial Call
No Activation  1  Positive 
No Activation  2  Positive 
Induced Rat Liver S9  1_S9  Positive 

Trial #: 1    Activation: No Activation    Date: 01/14/1987    Trial Call: Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Negative (Not Specified) 
0         
 50 1044 415 0.398 8.30 26.0 0.000
Test Chemical Benzidine dihydrochloride 
 0.5       
 50 1047 467 0.446 9.34 26.0 12.208 
1.6       
 50 1049 475 0.453 9.50 26.0 13.912 
5         
 50 1047 508 0.485 10.16 26.0 22.059 
16         
 50 1051 580 0.552 11.60 26.0 38.828 
50         
 0 0 0 0.000 0.00 26.0 N/A
Positive Control Mitomycin-C 
 0.0E-4    
 50 1042 572 0.549 11.44 26.0 38.096
Mitomycin-C 
 0.005     
 10 210 328 1.562 32.80 26.0 292.923
Trend: 5.213        
Probability: 0.000        

Trial #: 2    Activation: No Activation    Date: 03/31/1987    Trial Call: Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Negative (Not Specified) 
0         
 50 1049 406 0.387 8.12 26.0 0.000
Test Chemical Benzidine dihydrochloride 
1.6       
 50 1050 440 0.419 8.80 26.0 8.271 
5         
 50 1049 530 0.505 10.60 26.0 30.542 
16         
 50 1051 598 0.569 11.96 26.0 47.010 
50         
 50 1050 1142 1.088 22.84 31.0 181.013
Positive Control Mitomycin-C 
 0.0E-4    
 50 1050 561 0.534 11.22 26.0 38.046
Mitomycin-C 
 0.005     
 10 211 254 1.204 25.40 26.0 211.029
Trend: 20.618        
Probability: 0.000        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 01/14/1987    Trial Call: Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Negative (Not Specified) 
0         
 50 1045 441 0.422 8.82 26.0 0.000
Test Chemical Benzidine dihydrochloride 
5         
 50 1048 476 0.454 9.52 26.0 7.628 
16         
 50 1046 551 0.527 11.02 26.0 24.824 
50         
 50 1046 559 0.534 11.18 26.0 26.636 
100         
 50 1047 594 0.567 11.88 26.0 34.437
Positive Control Cyclophosphamide 
 0.1       
 50 1047 625 0.597 12.50 26.0 41.453
Cyclophosphamide 
 0.6       
 10 209 205 0.981 20.50 26.0 132.426
Trend: 5.387        
Probability: 0.000