University of California Berkeley seal E. O. Lawrence Berkeley National Laboratory seal
The Carcinogenic Potency Project

3,3′-Dimethoxybenzidine.2HCl (CAS 20325-40-0)
SMILES, InChI and Structure are below.
Rats and Mice: Cancer Test Summary
Rat Target Sites Mouse Target Sites TD50 (mg/kg/day)
Male Female Male Female Rat Mouse
ezy lgi liv orc per pre ski smi cli ezy lgi liv mgl orc ski ute liv no positive 1.04m 73.8n

Key to the Table Above

Positivity: For each chemical with a positive (carcinogenic) experiment in the Carcinogenic Potency Database (CPDB), results are included on carcinogenic potency (TD50) in each species and target sites in males and females. Positivity is determined by an author’s opinion in a published paper. If all experimental results in the CDPB are negative in a sex-species group, “no positive” appears. If the CPDB has no experiments in the sex-species group, “no test” appears. The summary presents the strongest evidence of carcinogenicity in each group. If there are both positive and negative experiments in a sex-species, the negative results are ignored in this Summary Table.
Target Site Codes:   cli = clitoral gland. ezy = ear/Zymbal’s gland. lgi = large intestine. liv = liver. mgl = mammary gland. orc = oral cavity (includes tissues of the mouth, oropharynx, pharynx, and larynx). per = peritoneal cavity. pre = preputial gland. ski = skin. smi = small intestine. ute = uterus. Target sites are listed if any author of published experimental results concluded that tumors were induced in that organ by the test agent. If there is more than one positive experiment in a sex-species, target sites listed may be from more than one experiment, e.g. if liver and lung are both listed, then liver may have been a target in one experiment and lung in another.
TD50: Our standardized measure of carcinogenic potency, TD50, is the daily dose rate in mg/kg body weight/day to induce tumors in half of test animals that would have remained tumor-free at zero dose. Whenever there is more than one positive experiment in a species, the reported TD50 value is a Harmonic Mean calculated using the TD50 value from the most potent target site in each positive experiment.
Superscripts:   m = There is more than one positive experiment in the species, and TD50 values from each positive experiment are used in the calculation of the reported Harmonic mean of TD50. n = No positive results in this species in the CPDB are statistically significant (p<.1).

The Carcinogenic Potency Database (CPDB) is a unique and widely used international resource of the results of 6540 chronic, long-term animal cancer tests on 1547 chemicals. The CPDB provides easy access to the bioassay literature, with qualitative and quantitative analyses of both positive and negative experiments that have been published over the past 50 years in the general literature through 2001 and by the National Cancer Institute/National Toxicology Program through 2004. The CPDB standardizes the diverse literature of cancer bioassays that vary widely in protocol, histopathological examination and nomenclature, and in the published author’s choices of what information to provide in their papers. Results are reported in the CPDB for tests in rats, mice, hamsters, dogs, and nonhuman primates.

For each experiment, information is included on species, strain, and sex of test animal; features of experimental protocol such as route of administration, duration of dosing, dose level(s) in mg/kg body weight/day, and duration of experiment; experimental results are provided on target organ, tumor type, and tumor incidence; carcinogenic potency (TD50) and its statistical significance; shape of the dose-response, author’s opinion as to carcinogenicity, and literature citation.

Only tests with dosing for at least ¼ the standard lifespan of the species and experiment length at least ½ the lifespan are included in the CPDB. Only routes of administration with whole body exposure are included. Doses are standardized, average dose rates in mg/kg/day. A description of methods used in the CPDB to standardize the diverse literature of animal cancer tests is presented for: 1) Criteria for inclusion of experiments 2) Standardization of average daily dose levels and 3) TD50 estimation for a standard lifespan. See Methods for other details.

TD50 provides a standardized quantitative measure that can be used for comparisons and analyses of many issues in carcinogenesis. The range of TD50 values across chemicals that are rodent carcinogens is more than 100 million-fold. More than half the chemicals tested are positive in at least one experiment.

A plot of all results on each experiment in the CPDB for this chemical is presented below. These results are the source information for the Cancer Test Summary table above.

3,3′-Dimethoxybenzidine.2HCl: All Experiments and Citations in CPDB

The definition of each code in the plot below will appear in a pop-up window when the field name in the header line is clicked, e.g., Strain, Site, Path. Each numbered line starts a new experiment and reports protocol information in black. Average daily dose-rates per kg body weight per day are in green. Remaining lines report experimental results in blue.

Abbreviations of fields in header line: # = the line number in the plot of all CPDB chemicals; Xpo = duration of dosing; Xpt = duration of experiment; Site = tissue; Path = tumor type; DR = dose-response; AuOp = author’s opinion about carcinogenicity; LoConf, UpConf = confidence limits (99%) on TD50; Inc = tumor incidence for each dose group.

See Guide to reading the plot for details on each field, using an example of one experiment.

See Help to improve readability, or to fit the plot onto the screen or a printed page.

Chemical (Synonym) CAS
# Species Sex Strain Route Xpo+Xpt PaperNum        0 Dose  1 Dose 2 Dose  3 Dose          Literature Reference or NCI/NTP:Site Path
Site Path Notes   TD50  DR Pval    AuOp LoConf UpConf   Cntrl   1 Inc  2 Inc   3 Inc                                                        Brkly Code

3,3'-DIMETHOXYBENZIDINE.2HCl 20325-40-0 2260 M f bcn wat 78w78 1919m 0 4.00mg 8.00mg 16.0mg 32.0mg 63.0mg Schieferstein;jact,9,71-77; 1990/pers.comm. hag ade kr no dre P=1. - n.s.s. 4/24 3/21 1/19 6/24 0/20 2/21 2/22 hag car kr no dre P=1. - n.s.s. 0/24 1/21 0/19 0/24 0/20 0/21 0/22 2261 M f bcn wat 26m26 1919n 0 4.00mg 8.00mg 16.0mg 32.0mg 63.0mg hag ade r no dre P=1. - n.s.s. 1/25 3/27 3/26 3/22 6/28 3/24 2/26 2262 M m bcn wat 78w78 1919m 0 3.33mg 6.67mg 13.3mg 26.7mg 52.5mg hag ade kr 3.56gm * P<.9 - n.s.s. 2/20 3/22 2/21 3/19 0/23 1/20 3/20 2263 M m bcn wat 26m26 1919n 0 3.33mg 6.67mg 13.3mg 26.7mg 52.5mg hag ade r no dre P=1. - n.s.s. 2/26 4/25 4/25 3/27 4/26 4/30 0/28 2264 M m icr eat 65w65 2594 : 0 Osanai;jsol,52,179-201;1976 liv hpt 73.8mg P<.3 + 21.4mg n.s.s. 7/34 11/17 2265 R f f34 wat 91w93 TR372 : 0 4.57mg 9.71mg 18.9mg MXB MXB 1.19mg * P<.0005 .844mg 1.72mg 9/60 37/45 67/75 53/60 cli:ade,anb,car,cnb; cvu:car,ppa; dsc:adc,adp; liv:hpc,nnd; mgl:adc; pal:sqc,sqp; phr:sqp; rec:adc,adp; ski:bca,bcc; ton:sqc,sqp; ute:ade,car; zym: ade,car,cnb. C cli MXA 1.60mg * P<.0005 c 1.12mg 2.39mg 7/60 27/45 48/75 41/60 cli:ade,anb,car,cnb. cli MXA 2.62mg * P<.0005 1.73mg 4.02mg 2/60 17/45 41/75 30/60 cli:car,cnb. S mgl MXA 3.24mg Z P<.0005 1.93mg 6.12mg 15/60 13/45 21/75 22/60 mgl:adc,ade,fba. S cli MXA 3.84mg * P<.0005 2.26mg 7.35mg 5/60 15/45 13/75 16/60 cli:ade,anb. S mgl MXA 6.22mg * P<.0005 2.91mg 24.8mg 14/60 11/45 9/75 6/60 mgl:ade,fba. S --- mnl 6.71mg * P<.003 2.98mg 51.2mg 21/60 15/45 12/75 4/60 S zym MXA 6.74mg * P<.0005 c 4.19mg 11.2mg 1/60 12/45 21/75 16/60 zym:ade,car,cnb. mgl fba 7.05mg * P<.002 3.09mg 44.0mg 14/60 11/45 9/75 4/60 S mgl adc 7.70mg Z P<.0005 c 4.23mg 14.0mg 1/60 2/45 14/75 20/60 zym MXA 8.41mg * P<.0005 4.92mg 15.3mg 1/60 10/45 17/75 13/60 zym:car,cnb. S pit MXA 8.84mg Z P<.002 3.83mg 47.8mg 15/60 9/45 5/75 8/60 pit:ade,pda. S pit MXA 9.40mg Z P<.003 3.97mg 66.1mg 17/60 9/45 5/75 8/60 pit:ade,pda,pdc. S ski MXA 10.2mg * P<.0005 c 4.47mg 29.6mg 0/60 4/45 3/75 2/60 ski:bca,bcc. ute esp 11.6mg * P<.002 4.90mg 62.8mg 6/60 8/45 7/75 5/60 S ski bca 12.3mg * P<.0005 5.10mg 38.6mg 0/60 3/45 3/75 2/60 S MXA MXA 13.8mg * P<.0005 c 5.69mg 50.3mg 2/60 2/45 6/75 5/60 pal:sqc,sqp; phr:sqp; ton:sqc,sqp. MXA MXA 14.0mg * P<.0005 c 5.69mg 47.3mg 0/60 4/45 2/75 2/60 cvu:car,ppa; ute:ade,car. MXA MXA 15.8mg * P<.0005 6.01mg 63.7mg 0/60 3/45 1/75 2/60 cvu:ppa; ute:ade. S MXA sqp 16.6mg * P<.002 6.07mg 2/60 2/45 3/75 3/60 pal:sqp; ton:sqp. S ton MXA 19.9mg * P<.0005 7.17mg 1/60 2/45 2/75 4/60 ton:sqc,sqp. S zym ade 27.5mg * P<.0005 11.6mg 94.6mg 0/60 3/45 4/75 3/60 S liv MXA 33.3mg Z P<.002 c 9.60mg 0/60 1/45 0/75 3/60 liv:hpc,nnd. MXA MXA 44.3mg * P<.003 c 10.7mg 0/60 1/45 1/75 3/60 dsc:adc,adp; rec:adc,adp. MXA sqc * P<.01 40.3mg 8.26gm 0/60 0/45 3/75 2/60 pal:sqc; ton:sqc. S pal MXA 45.3mg * P<.04 10.6mg n.s.s. 1/60 0/45 4/75 1/60 pal:sqc,sqp. S pal sqp 47.8mg * P<.04 10.8mg n.s.s. 1/60 0/45 3/75 1/60 S TBA MXB 1.09mg Z P<.0005 .764mg 1.64mg 48/60 42/45 73/75 57/60 liv MXB 33.3mg Z P<.002 9.60mg 0/60 1/45 0/75 3/60 liv:hpa,hpc,nnd. 2266 R m f34 wat 88w92 TR372 : 0 4.00mg 8.50mg 16.5mg tes MXA a .612mg Z P<.0005 .412mg .961mg 57/60 39/45 68/75 42/60 tes:iab,ica. S MXB MXB a .677mg * P<.0005 .461mg 1.03mg 22/60 41/45 71/75 60/60 ---:msb,msm; asc:adp; cec:muc; col:adc; dsc:adc, adp; duo:adc,muc; ilm:adc; jej:adc,muc; liv:hpc,nnd; pal:sqc; phr:sqp; pre:ade,anb,car,cnb; rec:adc, adp; ski:bca,bcc,sbr,sea,sqc,sqp; ton:sqc,sqp; zym:ade,anb,car,cnb. C ski MXA a .767mg * P<.0005 c .507mg 1.16mg 2/60 33/45 56/75 41/60 ski:bca,bcc,sbr,sea. ski MXA a .770mg * P<.0005 .508mg 1.17mg 2/60 32/45 54/75 40/60 ski:bca,bcc. S ski MXA a .785mg * P<.0005 .515mg 1.21mg 1/60 32/45 49/75 35/60 ski:bca,sea. S ski bca a .789mg * P<.0005 .516mg 1.22mg 1/60 31/45 47/75 35/60 S pre MXA a 1.78mg Z P<.0005 c 1.06mg 3.19mg 16/60 12/45 33/75 29/60 pre:ade,anb,car,cnb. ski MXA a 2.01mg * P<.0005 c 1.20mg 3.29mg 0/60 13/45 28/75 22/60 ski:sqc,sqp. amd MXA a 2.06mg * P<.0005 1.18mg 4.09mg 14/60 17/45 23/75 9/60 amd:pbb,pob. S amd MXA a 2.11mg * P<.0005 1.22mg 4.24mg 15/60 18/45 23/75 9/60 amd:pbb,phm,pob. S ski sqc a 2.35mg Z P<.0005 1.38mg 3.92mg 0/60 9/45 24/75 21/60 S --- mnl a 2.50mg * P<.0005 1.23mg 7.45mg 19/60 17/45 17/75 4/60 S zym MXA a 3.02mg * P<.0005 c 1.65mg 5.21mg 0/60 10/45 25/75 30/60 zym:ade,anb,car,cnb. pre MXA a 3.28mg Z P<.0005 1.67mg 7.70mg 14/60 6/45 19/75 12/60 pre:ade,anb. S MXA MXA a 4.22mg * P<.0005 c 2.04mg 9.43mg 1/60 8/45 10/75 11/60 pal:sqc; phr:sqp; ton:sqc,sqp. MXA sqp a 4.49mg * P<.0005 2.11mg 10.6mg 1/60 7/45 10/75 9/60 phr:sqp; ton:sqp. S pre MXA a 4.65mg * P<.0005 2.28mg 9.77mg 2/60 6/45 15/75 19/60 pre:car,cnb. S thy MXA a 4.70mg * P<.0005 2.01mg 17.8mg 6/60 7/45 7/75 2/60 thy:cca,ccr. S sub MXA a 5.19mg * P<.0005 2.13mg 14.9mg 0/60 6/45 6/75 4/60 sub:fib,nfm. S zym MXA a 5.84mg * P<.0005 2.51mg 13.8mg 0/60 4/45 11/75 9/60 zym:ade,anb. S sub MXA a 6.49mg * P<.0005 2.51mg 25.8mg 2/60 6/45 6/75 5/60 sub:fbs,fib,nfm,sar. S ski MXA a 6.50mg * P<.0005 3.44mg 11.5mg 1/60 4/45 18/75 18/60 ski:bcc,sbr. S ski bcc a 6.55mg * P<.0005 3.46mg 11.7mg 1/60 4/45 18/75 17/60 S ski sqp a 6.60mg * P<.0005 2.81mg 16.4mg 0/60 5/45 7/75 5/60 S zym MXA a 6.71mg * P<.0005 3.25mg 11.7mg 0/60 7/45 14/75 21/60 zym:car,cnb. S thy cca a 6.92mg * P<.003 2.61mg 57.2mg 6/60 6/45 5/75 1/60 S liv MXA a 7.80mg * P<.0005 c 3.05mg 21.9mg 1/60 4/45 7/75 8/60 liv:hpc,nnd. pal MXA a 8.21mg * P<.0005 3.05mg 25.6mg 0/60 4/45 5/75 4/60 pal:sqc,sqp. S ton MXA a 8.25mg * P<.0005 3.39mg 23.6mg 1/60 4/45 5/75 8/60 ton:sqc,sqp. S pal sqp a 8.35mg * P<.0005 3.06mg 27.2mg 0/60 4/45 5/75 3/60 S MXA MXA a 8.44mg * P<.0005 c 3.04mg 27.0mg 0/60 4/45 7/75 5/60 duo:adc,muc; ilm:adc; jej:adc,muc. ski ker a 9.13mg * P<.0005 3.33mg 42.4mg 1/60 5/45 7/75 1/60 S ton sqp a 9.16mg * P<.0005 3.57mg 28.6mg 1/60 3/45 5/75 7/60 S MXA MXA a 9.91mg * P<.0005 c 3.90mg 23.1mg 0/60 1/45 8/75 8/60 asc:adp; cec:muc; col:adc; dsc:adc,adp; rec:adc, adp. MXA asl a 10.9mg * P<.0005 e 3.35mg 57.4mg 0/60 2/45 3/75 1/60 bra:asl; clb:asl; crb:asl; crl:asl. liv nnd a 12.4mg * P<.0005 4.43mg 30.2mg 0/60 3/45 7/75 6/60 S MXA adp a 13.6mg * P<.0005 4.44mg 42.8mg 0/60 1/45 4/75 5/60 asc:adp; dsc:adp; rec:adp. S sub MXA a 13.6mg * P<.0005 4.44mg 50.4mg 0/60 4/45 4/75 3/60 sub:fbs,fib. S sub fib a 13.9mg * P<.0005 4.46mg 57.2mg 0/60 4/45 4/75 2/60 S ski MXA a 24.6mg * P<.009 5.01mg 1.67gm 0/60 2/45 3/75 2/60 ski:sbr,sea. S --- MXA a 27.4mg * P<.002 c 7.62mg 2/60 1/45 7/75 6/60 ---:msb,msm. MXA MXA a 38.0mg * P<.002 10.5mg 0/60 0/45 4/75 3/60 cec:muc; col:adc; dsc:adc; rec:adc. S TBA MXB a .565mg Z P<.0005 .386mg .868mg 59/60 45/45 75/75 60/60 liv MXB a 7.80mg * P<.0005 3.05mg 21.9mg 1/60 4/45 7/75 8/60 liv:hpa,hpc,nnd.

Mutagenicity in Salmonella: positive
SMILES Code for 3,3′-Dimethoxybenzidine.2HCl: NC1=CC=C(C2=CC=C(N)C(OC)=C2)C=C1OC.Cl.Cl
InChI Code for 3,3′-Dimethoxybenzidine.2HCl: InChI=1/C14H16N2O2.2ClH/c1-17-13-7-9(3-5-11(13)15)10-4-6-12(16)14(8-10)18-2;;/h3-8H,15-16H2,1-2H3;2*1H
Source for SMILES and InChI: USEPA Distributed Structure-Searchable Toxicity (DSSTox) Database
Chemical Structure for 3,3′-Dimethoxybenzidine.2HCl: Chemical Structure
Source for structure: National Library of Medicine ChemIDPlus

See full CPDB Summary Table on 1547 chemicals. See Full CPDB for all results on 6540 experiments of 1547 chemicals.

A complete list of CPDB chemicals, which is searchable by name or by CAS number, is available here.

For a compendium of CPDB results organized by target organ, which lists all chemicals in each species that induced tumors in each of 35 organs, see Summary Table by Target Organ.

The CPDB is available in several formats that permit printing and downloading into spreadsheets and statistical databases.

  1. A plot of the CPDB presents results of 1547 experiments on 6540 chemicals in an easily readable format that has been used in publications of the CPDB.
  2. A Screen version plot for use on a single computer screen, with the same data.
  3. Excel version of the same data.
  4. Tab-separated versions of the same data, which can be easily read into databases.

A Supplementary Dataset gives details on dosing and survival for each experiment.

Relatively precise estimates of the lower confidence limit on the TD10 (LTD10) are readily calculated from the TD50 and its lower confidence limit, which are reported in the CPDB. For researchers and regulatory agencies interested in LTD10 values, we provide them in an Excel spreadsheet.

PDF versions of our publications of analyses using the CPDB are available, organized by year and by research topic.

Carcinogenic Potency Database Project (CPDB) Home Page
For more information about this Web Page, contact Specialized Information Services (
Last updated: October 3, 2007

PDF documents are best viewed with the free Adobe® Reader
Excel documents are best viewed with the free Excel® Viewer