1986 survey of genetic toxicology testing in industry, government contract, and academic laboratories.

Results of the 1986 Genetic Toxicology Association's survey of industrial, government, contract, and academic laboratories on the status of several assays in genetic toxicology are presented below. 1. The most commonly used assay was the Salmonella typhimurium/mammalian microsomal (Ames) assay, which was used by 83% of all respondents. 2. The next five (5) most commonly used assays were in vitro cytogenetics (72%), in vivo cytogenetics (59%), CHO HGPRT gene mutation (55%), the micronucleus assay (53%), and L517BY gene mutation (45%). 3. The assay showing the greatest percentage increase in routine use was the micronucleus assay which went from 14% in 1984 to 34% in 1986, an increase of 20%. 4. Other assays which increased in routine use were CHO HGPRT mutation (+18%); in vitro cytogenetics (+14%); L5178Y gene mutation (+9%), and the Ames assay (+5%). 5. Routine use of in vitro UDS assays declined by 6%; use of in vitro SCE assays declined by 12%. 6. There was no change in the rate of routine use of in vivo cytogenetics or in vivo SCE assays. 7. Assays routinely performed on contract included the Salmonella assay, CHO HGPRT gene mutation, in vitro cytogenetics, in vitro UDS, in vivo cytogenetics, the micronucleus assay, L5178Y gene mutation, and the Drosophila sex-linked recessive lethal assay. 8. Four assays were being developed by five or more laboratories. These included in vitro SCE (8); the micronucleus assay (7); in vivo SCE (6); and DNA adduct formation (5). 9. A total of 17 assays had been abandoned by one or more laboratories. However, since no assay had been given up by more than three laboratories no conclusions can be drawn about the overall robustness of any of the assays on the survey form.

1984 survey of genetic toxicology testing in industry, government and academic laboratories.

Compiled results of the 1984 Genetic Toxicology Association's survey representing a total of 72 responses from governmental, contract, industrial, or academic institutions regarding the status of 32 recognized genetic toxicology assays, were as follows: Most frequently performed on a routine or occasional basis: Ames (76% of all respondents routinely or occasionally perform the assay); in vitro cytogenetics (59%); in vivo Bone Marrow Cytogenetics (56%); in vitro Sister Chromatid Exchange (56%); in vitro Unscheduled DNA Synthesis (43%); Mutation in CHO HGPRT (42%); Micronucleus test (41%); Mutation in L5178Y (36%). Assay associated with in vivo and in vitro chromosomal end points (aberrations, SCE, micronucleus) constituted the major area of increased use since the 1982 survey. Assays of developmental interest included DNAS binding both in vitro and in vivo and UDS in vivo. Quantitative analysis of the data indicated: Industrial and contract laboratories processed the largest volumes of chemicals over the broadest spectrum of assays. Industrial laboratories showed a marked increased since 1982 in testing compounds in-house. The number of assays sponsored by governmental laboratories, both in-house or subcontracted, increased from 1982. Academic institutions ranked lowest in number of compounds examined.

A survey of genetic toxicology testing in industry, contract laboratories and government.

Genetic Toxicology Association members from governmental, contract and industrial laboratories were surveyed to determine the status of 28 recognized genetic toxicology assays in their laboratories. Compiled results of the 1982 questionnaire indicate that the Ames test, in vitro cytogenetics, in vitro sister chromatid exchange, unscheduled DNA synthesis, mutation in Chinese hamster ovary cells at the HGPRT locus, and in vivo bone marrow assays were the most frequently performed routine tests by the majority of laboratory affiliations. Investigation of the number of transformation assays performed indicated a high routine use. However, their use was largely confined to contract laboratories. Volume analysis of chemicals tested for 1982 indicated: (i) contract laboratories studied the largest number of compounds over the broadest spectrum of assays; (ii) industrial laboratories processed more compounds in the Ames test than any other laboratory group; and (iii) governmental laboratories ranked lowest in numbers of compounds evaluated both in-house and/or subcontracted .

An evaluation of the host-mediated assay and body fluid analysis. A report of the U.S. Environmental Protection Agency Gene-Tox Program.

The methodologies and status of the Host-Mediated Assay were reviewed using the published literature available up to June 1980. The Working Group reviewed 274 documents, including abstracts, research articles, review articles, and publicly available contracts and grant final reports. From this group, abstracts and reviews were rejected from critical evaluation. 77 documents were accepted and reviewed by the Working Group and the test results summarized. These selected documents yielded 208 chemicals that were evaluated in th host-mediated assay. Of these chemicals, 133 were mutagenic in this assay with one or more indicators. 76 chemicals, several of which are not considered to be carcinogenic, were not detected by any of the indicators. Of the 208 chemicals, 125 had been tested in carcinogenicity assay in rodents. 90, or 71%, of the carcinogens were detected as mutagens in the Host-Mediated Assay. In several cases, those carcinogens not detected may have been negative because of improper selection of the indicator. The Working Group concluded that the Host-Mediated Assay is an important test in mutagenicity/carcinogenicity research and that, by proper selection of protocols and indicators, valuable information can be gained that otherwise would be overlooked strict, in vitro assays.

The effect of plant growth substances and natural products on RNA and DNA synthesis in leukocytes.

The effect of auxins, cytokinins, gibberellins and phenolics on the incorporation of uridine and thymidine into the nucleic acids of human leukocytes was examined. Both the stimulation and inhibition of the incorporation of the precursors was noted. The auxins consistently promoted the incorporation of uridine.