The Carcinogenic Potency Project

Isoprene (CAS 78-79-5)
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
kid mgl tes mgl hag hmo liv lun sto vsc hag pit vsc 313m 274m

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:   hag = harderian gland. hmo = hematopoietic system. kid = kidney. liv = liver. lun = lung. mgl = mammary gland. pit = pituitary gland. sto = stomach. tes = testes. vsc = vascular system. 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.

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.

Isoprene: 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



ISOPRENE  (2-methyl-1,3-butadiene) 78-79-5
3410 M f b6c inh 19m24 2258o                         0    8.89mg  62.3mg                                Placke;txcy,113,253-262;1996
 pit pda e      247.mg * P<.03   +  97.1mg n.s.s.   1/49    6/46    9/49
 hag ade e      319.mg * P<.03   +  122.mg n.s.s.   2/49    3/49    8/49
 spl hes eh     682.mg * P<.1    +  201.mg n.s.s.   1/50    1/49    4/50
 liv hpa e      no dre   P=1.       310.mg n.s.s.   4/50    6/50    3/50
 liv hpc e      no dre   P=1.       322.mg n.s.s.   2/50    4/50    2/50
 lun a/a e      no dre   P=1.       227.mg n.s.s.   5/50    6/50    5/50
3411 M m b6c inh 26w53 TX31 :                        0    24.9mg  78.6mg  250.mg  787.mg  2.51gm
 hag ade        96.8mg Z P<.003  c  45.4mg 603.mg   2/30    6/30    4/30   14/30  (13/30   12/30)
 hag MXA        96.8mg Z P<.003  c  45.4mg 603.mg   2/30    6/30    4/30   14/30  (13/30   12/30)                     hag:ade,car.
 liv hpa        150.mg Z P<.0005    82.0mg 425.mg   4/30    2/30    6/30   15/30   18/30  (16/30)                                  S
 liv MXA        183.mg Z P<.0005 c  92.0mg 753.mg   7/30    3/30    7/30   15/30   18/30  (17/30)                     liv:hpa,hpc.
 MXB MXB        355.mg Z P<.0005    176.mg 1.45gm  11/30   10/30   10/30   23/30   25/30   23/30    for:sqc,sqp; hag:ade,car; liv:
                                                                                                             hpa,hpc; lun:a/a,a/c. C
 lun MXA        752.mg * P<.0005 c  371.mg 2.96gm   2/30    2/30    1/30    5/30   10/30    9/30                      lun:a/a,a/c.
 lun a/a        836.mg * P<.0005    403.mg 3.79gm   2/30    2/30    1/30    4/30   10/30    8/30                                   S
 liv hpc        1.27gm * P<.006     523.mg 17.8gm   4/30    1/30    3/30    5/30    4/30    9/30                                   S
 for MXA        1.31gm * P<.0005 c  657.mg 3.48gm   0/30    0/30    0/30    1/30    4/30    6/30                      for:sqc,sqp.
 for sqp        1.86gm * P<.0005    838.mg 6.55gm   0/30    0/30    0/30    1/30    2/30    5/30                                   S
 lun a/c        2.79gm * P<.004     1.06gm 29.6gm   0/30    0/30    0/30    1/30    1/30    3/30                                   S
 for sqc        4.85gm * P<.04      1.47gm n.s.s.   0/30    0/30    0/30    0/30    2/30    1/30                                   S
 hag car        14.7gm * P<.4       2.39gm n.s.s.   0/30    0/30    0/30    0/30    1/30    0/30
 TBA MXB        348.mg Z P<.0005    175.mg 1.37gm  12/30   10/30   11/30   23/30   26/30   24/30
 liv MXB        183.mg Z P<.0005    92.0mg 753.mg   7/30    3/30    7/30   15/30   18/30  (17/30)                 liv:hpa,hpb,hpc.
 lun MXB        752.mg * P<.0005    371.mg 2.96gm   2/30    2/30    1/30    5/30   10/30    9/30                      lun:a/a,a/c.
3412 M m b6c inh  9m24 2258m                         0    25.9mg  51.9mg  892.mg                        Placke;txcy,113,253-262;1996
 hag ade e      739.mg * P<.0005 +  426.mg 1.59gm   4/47   13/48   12/50   31/49
 lun a/a e      908.mg * P<.0005 +  510.mg 2.12gm  11/50    8/50   10/50   29/49
 liv hpa e      1.07gm * P<.0005 +  530.mg 4.46gm  11/50   14/49   22/50   28/47
 lmr hcs e      4.43gm * P<.003  +  1.80gm 30.8gm   0/50    2/50    1/50    7/50
 liv hpc e      2.33gm * P<.02   +  958.mg n.s.s.   9/50   11/49   10/50   18/47
 lun a/c e      9.23gm * P<.03   +  2.82gm n.s.s.   0/50    0/50    1/50    3/49
 for sqp e      15.6gm * P<.03      3.85gm n.s.s.   0/50    0/47    0/49    2/47
 hea hes e      32.9gm * P<.2       5.36gm n.s.s.   0/49    0/49    0/50    1/49
 hag car e      no dre   P=1.       7.87gm n.s.s.   0/47    0/48    2/50    0/49
 spl hes e      no dre   P=1.       8.16gm n.s.s.   1/49    1/47    3/50    0/47
3413 M m b6c inh 80w96 2258n                         0    892.mg
 hag ade e      711.mg   P<.0005 +  423.mg 1.46gm   4/47   28/50
 lmr hcs e      3.45gm   P<.002  +  1.49gm 14.5gm   0/50    7/50
 liv hpa e      1.76gm   P<.04   +  739.mg n.s.s.  11/50   21/50
 lun a/c e      8.41gm   P<.04   +  2.55gm n.s.s.   0/50    3/50
 liv hpc e      3.29gm   P<.2    +  1.07gm n.s.s.   9/50   15/50
 lun a/a e      4.81gm   P<.4       1.17gm n.s.s.  11/50   15/50
 hag car e      12.8gm   P<.2       3.14gm n.s.s.   0/47    2/50
 for sqp e      25.8gm   P<.3       4.20gm n.s.s.   0/50    1/50
 for sqc e      25.8gm   P<.3       4.20gm n.s.s.   0/50    1/50
 hea hes e      25.8gm   P<.3       4.20gm n.s.s.   0/49    1/50
 spl hes e      25.8gm   P<.6       3.46gm n.s.s.   1/49    2/50
3414 M m b6c inh 19m24 2258o                         0    7.41mg  51.9mg  227.mg  568.mg  1.78gm
 hag ade e      881.mg * P<.0005 +  601.mg 1.43gm   4/47    4/49    9/50   17/50   26/49   35/50
 liv hpa e      1.57gm * P<.0005 +  891.mg 4.07gm  11/50   12/50   15/50   24/50   27/48   30/50
 lun a/a e      1.66gm * P<.0005 +  997.mg 3.62gm  11/50   16/50    4/50   13/50   23/50   30/50
 lun a/c e      6.68gm * P<.0005 +  4.02gm 28.8gm   0/50    1/50    2/50    1/50    7/50    7/50
 for sqc e      22.2gm * P<.008  +  7.68gm 740.gm   0/50    0/48    0/50    1/50    0/47    3/50
 liv hpc e      4.85gm * P<.03   +  2.00gm n.s.s.   9/50    6/50    9/50   16/50   17/48   16/50
 hag car e      15.0gm * P<.02   +  6.10gm n.s.s.   0/47    0/49    0/50    1/50    3/49    2/50
 for sqp e      45.0gm * P<.07      11.1gm n.s.s.   0/50    0/48    0/50    0/50    1/47    1/50
 hea hes eh     39.0gm * P<.4    +  8.07gm n.s.s.   0/49    0/50    0/50    2/50    1/50    1/50
 lmr hcs e      150.gm * P<.9       8.45gm n.s.s.   0/50    2/50    2/50    4/50    2/50    2/50
 spl hes e      no dre   P=1.       13.5gm n.s.s.   1/49    3/48    2/50    1/50    2/48    1/49
3415 R f f34 inh 24m24 TR486 :                       0    45.9mg  146.mg  1.46gm
 mgl fbm        206.mg Z P<.02   p  93.9mg n.s.s.   7/50   12/50   19/50  (17/50)
 mgl MXA        3.34gm Z P<.4    p  833.mg n.s.s.  19/50   35/50   32/50   32/50                                      mgl:fba,fbm.
 bra mag        30.8gm * P<.2    e  5.02gm n.s.s.   0/50    0/50    0/50    1/50
 brm grb        40.6gm * P<.5    e  4.69gm n.s.s.   0/50    1/50    0/50    1/50
 brm sar        50.8gm * P<.5    e  5.83gm n.s.s.   0/50    1/50    0/50    1/50
 bra mbm        52.8gm * P<.2    e  8.61gm n.s.s.   0/50    0/50    0/50    1/50
 bra asb        no dre   P=1.    e  6.35gm n.s.s.   0/50    0/50    1/50    0/50
 TBA MXB        6.94gm * P<.8       752.mg n.s.s.  49/50   48/50   49/50   48/50
 liv MXB        25.3gm * P<.4       3.90gm n.s.s.   0/50    0/50    1/50    1/50                                  liv:hpa,hpb,hpc.
3416 R m f34 inh 24m24 TR486 :                       0    32.1mg  102.mg  1.02gm
 mgl fba        655.mg * P<.0005 c  345.mg 1.70gm   2/50    4/50    6/50   21/50
 mgl MXA        655.mg * P<.0005 c  345.mg 1.70gm   2/50    4/50    6/50   21/50                                      mgl:fba,fbm.
 mgl MXA        670.mg * P<.0005 c  347.mg 1.86gm   2/50    5/50    7/50   21/50                                      mgl:car,fba.
 mgl fbm        2.22gm * P<.003  c  870.mg 15.0gm   1/50    1/50    0/50    7/50
 kid MXA        3.15gm * P<.02      1.10gm n.s.s.   0/50    2/50    2/50    6/50                                      kid:rua,ruc. S
 kid rua        3.15gm * P<.02   c  1.10gm n.s.s.   0/50    2/50    2/50    6/50
 tes MXA        914.mg * P<.2    c  299.mg n.s.s.  33/50   37/50   44/50   48/50                                      tes:iab,ica.
 MXB MXB        988.mg * P<.2       308.mg n.s.s.  33/50   39/50   44/50   48/50            kid:rua; mgl:car,fba,fbm; tes:iab,ica. C
 mgl car        7.88gm * P<.3    c  1.50gm n.s.s.   0/50    1/50    1/50    2/50
 TBA MXB        no dre   P=1.       541.mg n.s.s.  49/50   50/50   49/50   47/50
 liv MXB        no dre   P=1.       4.74gm n.s.s.   0/50    3/50    0/50    0/50                                  liv:hpa,hpb,hpc.
3417 R m f34 inh 26w52 TX31                          0    5.11mg  16.1mg  51.1mg  161.mg  511.mg
 tes ica        316.mg * P<.03   e  122.mg n.s.s.   3/30    3/30    4/30    7/30    8/30    9/30
 liv MXB        no dre   P=1.       5.41mg n.s.s.   0/30    0/30    0/30    0/30    0/30    0/30                      liv:hpa,hpc.
3418 R m f34 inh 24m24 TR486 with step               0    31.9mg  102.mg  1.01gm
 kid rua        2.29gm * P<.0005 c  1.10gm 9.34gm   2/50    4/50    8/50   15/50
 kid MXA        2.29gm * P<.0005    1.10gm 9.34gm   2/50    4/50    8/50   15/50                                      kid:rua,ruc. S
Mutagenicity in Salmonella: negative
SMILES Code for Isoprene: CC(=C)C=C
InChI Code for Isoprene: InChI=1/C5H8/c1-4-5(2)3/h4H,1-2H2,3H3
Source for SMILES and InChI: USEPA Distributed Structure-Searchable Toxicity (DSSTox) Database
Chemical Structure for Isoprene: 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.

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Last updated: October 3, 2007