The Carcinogenic Potency Project (CPDB)

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 that is important in the interpretation of bioassays: species, strain, and sex of test animal; features of experimental protocol such as route of administration, duration of dosing, average daily dose-rate in mg/kg body weight/day, and duration of experiment; 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. The TD₅₀, our numerical description of carcinogenic potency, is the daily dose-rate in mg/kg/body weight/day for life to induce tumors in half of test animals that would have remained tumor-free at zero dose. 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.

A description of methods used in the CPDB to standardize the diverse literature of animal cancer tests is presented for:

The boxes above link to several formats of the CPDB that are suitable for (1) screen viewing, (2) printing or (3) reading the data into statistical packages and spreadsheets. Codes used in the CPDB are defined in appendices. The Web site is fully searchable by all fields and includes SMILES, InChI codes and structures for all chemicals.

A summary table by chemical reports a one-line summary of positivity, potency and target sites for each chemical, whether positive or negative for carcinogenicity. A compendium of CPDB results organized by target organ reports all chemicals that induce tumors in each of 35 target organs.

A single Web page on each chemical gives all results in the CPDB.

Together, the plot of the CPDB, the bibliography of papers included in the database, and the summary tables provide a guide to the literature of chronic, long-term animal cancer tests, as well as an accessible research resource.

Several formats of the CPDB are available on this Web site:

A separate Web page of results for each of the 1547 chemicals in the CPDB.
A plot, or graphic display, of the CPDB presents results of each experiment in an easily readable format that has been used in publications of the CPDB.
A Screen version plot that can be easily read on a single computer screen. Data are the same as in the published format.
Excel version of the same data.
Tab-separated versions of the same data, which can be easily read into statistical databases.
Summary Table by Chemical
Summary Table by Target Organ

Estimates of the lower confidence on TD₁₀ are provided in an Excel spreadsheet.

The Web site provides a single Web page on each individual chemical in the CPDB, which is accessible from a list of chemicals. These Web pages of individual chemicals provide both summary and complete information about each chemical in the CPDB. Each page reports a summary of results for that chemical in each sex-species tested, including positivity, target sites and TD₅₀ values. Detailed results from each experiment on that particular chemical are given in a plot format suitable for screen viewing. Chemical structure, InChI and SMILES codes are reported.

A new web page presents a graphic that uses a Margin of Exposure Index to provide a broad perspective on possible cancer hazards from human exposures to chemicals that cause cancer in high dose rodent cancer tests. Exposures include high historical exposures to workers, pharmaceuticals, natural chemicals in the average diet, air pollutants, food additives, and pesticide residues. Human exposure levels range from close to the rodent carcinogenic dose for a few historical exposures in the workplace to a billion times less the rodent carcinogenic dose for some pesticide residues. Human consumption of the background of natural chemicals in food is usually closer to the rodent carcinogenic dose than pesticide residues or pollutants, and half the natural chemicals tested are carcinogenic in high dose tests. Recent risk assessment methods indicate that for some chemicals the mechanism of carcinogenesis in rodents at high dose is not relevant to humans.

Our publications are provided as PDF files on this Web site, listed by year and by topic. Broad research areas include: methodological analyses of bioassay results; species comparisons in carcinogenicity and potency; target organs of chemical carcinogens; mechanisms of carcinogenesis and the interpretation of the high proportion of chemicals that test positive; risk assessment techniques; the background of naturally-occurring chemicals that are rodent carcinogens; setting priorities among possible cancer hazards from natural and synthetic rodent carcinogens; occupational exposures and possible cancer hazards; disparities in cancer risk estimates for pesticide residues in food; and misconceptions about the causes of cancer.

The CPDB was developed between 1980 and 2005 by the following people:

Lois Swirsky Gold, Bruce N. Ames, Leslie Bernstein, Mark Blumenthal, Kenneth Chow, Maria Da Costa, Margarita de Veciana, Susan Eisenberg, Georganne Backman Garfinkel, Thomas Haggin, William R. Havender, N. Kim Hooper, Robert Levinson, Peggy Lopipero, Renae Magaw, Neela B. Manley, Peter M. MacLeod, Richard Peto, Malcolm C. Pike, Lars Rohrbach, Charles B. Sawyer, Thomas H. Slone, Mark Smith, Bonnie R. Stern, Michael Wong.