Mutagenicity Assessment of Homologous Series of Methyl Ester Sulphonates (MES) Using the Bacterial Reverse Mutation (Ames) Test

Methyl ester sulphonate (MES) is an anionic surfactant that is suitable to be used as an active ingredient in household products. Four palm-based MES compounds with various carbon chains, namely C12, C14, C16 and C16/18 MES, were assayed by the in vitro bacterial reverse mutation (Ames) test in the Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and the Escherichia coli strain WP2 uvrA, with the aim of establishing the safety data of the compounds, specifically their mutagenicity. The test was also carried out on linear alkylbenzene sulphonate (LAS) for comparison. The plate incorporation method was conducted according to the Organization for Economic Cooperation and Development (OECD) Test Guideline 471. All compounds were tested at five analysable non-cytotoxic concentrations, varying from .001 mg/plate to 5 mg/plate, with and without S-9 metabolic activation. All tested concentrations showed no significant increase in the number of revertant colonies compared to revertant colonies of the negative control. The Ames test indicated that each concentration of C12, C14, C16, C16/18 MES, and LAS used in this study induced neither base-pair substitutions nor frame-shift mutations in the S. typhimurium strains TA98, TA100, TA1535, and TA1537 and the E. coli strain WP2 uvrA. The results showed that C12, C14, C16 and C16/18 MES have no potential mutagenic properties in the presence and absence of S-9 metabolic activation, similarly to LAS. Therefore, the MES is safe to be used as an alternative to petroleum-based surfactants for household cleaning products.

Food safety considerations and research priorities for the cultured meat and seafood industry

Cell-cultured meat and seafood offer a sustainable opportunity to meet the world's increasing demand for protein in a climate-changed world. A responsible, data-driven approach to assess and demonstrate safety of cell-cultured meat and seafood can support consumer acceptance and help fully realize the potential of these products. As an initial step toward a thorough demonstration of safety, this review identifies hazards that could be introduced during manufacturing, evaluates applicability of existing safety assessment approaches, and highlights research priorities that could support safe commercialization. Input was gathered from members of the cultured meat and seafood industry, researchers, regulators, and food safety experts. A series of workshops were held with 87 industry representatives and researchers to create a modular manufacturing process diagram, which served as a framework to identify potential chemical and biological hazards along the steps of the manufacturing process that could affect the safety of a final food product. Interviews and feedback on draft documents validated the process diagram and supported hazard identification and evaluation of applicable safety methods. Most hazards are not expected to be novel; therefore, safety assessment methods from a range of fields, such as conventional and novel foods, foods produced from biotechnology, pharmaceuticals, and so forth, are likely to be applicable. However, additional assessment of novel inputs or products with significant differences from existing foods may be necessary. Further research on the safety of the inputs and associated residues, potential for contamination, and development of standardized safety assessment approaches (particularly animal-free methods) is recommended.

Modifications of the bacterial reverse mutation test reveals mutagenicity of TiO(2) nanoparticles and byproducts from a sunscreen TiO(2)-based nanocomposite

The bacterial reverse mutation test, recommended by the Organization for Economic Co-operation and Development (OECD) to determine genotoxicity of chemical compounds, has been recently used by several authors to investigate nanoparticles. Surprisingly, test results have been negative, whereas in vitro mammalian cell tests often give positive genotoxic responses. In the present study, we used the fluctuation test procedure with the Salmonella typhimurium strains TA97a, TA98, TA100 and TA102 to determine the mutagenic potential of TiO(2) nanoparticles (NP-TiO(2)) and showed that, when it is used conventionally, this test is not suitable for nanoparticle genotoxicity assessment. Indeed, the medium used during exposure prevents electrostatic interactions between bacterial cells and nanoparticles, leading to false-negative responses. We showed that a simple pre-exposure of bacteria to NP-TiO(2) in a low ionic strength solution (NaCl 10mM) at a pH below the nanoparticle isoelectric points (pH 5.5) can strongly improve the accuracy of the test. Thus, based on these improvements, we have demonstrated the genotoxicity of the engineered NP-TiO(2) tested and a NP-TiO(2) byproduct from a sunscreen nanocomposite. It was also shown that strain TA102 is more sensitive than the other strains, suggesting an oxidative stress-mediated mechanism of genotoxicity.

The mutagenicity of edible mushrooms in a histidine-independent bacterial test system

In mutagenicity screening of 40 edible mushroom species, special attention was paid to the selection of the test system, since complex mixtures such as mushroom extracts may interfere with the genetic endpoint of the assay. This paper shows that the weak mutagenicity of some mushrooms in the Ames test, as reported by several authors, is actually an artefact due to the presence of free histidine in the mushroom extracts, which apparently increases the reversion of bacteria from histidine auxotrophy to prototrophy. To avoid amino-acid interaction, a combination of the forward mutation assay to 8-azaguanine resistance in Salmonella typhimurium TM677 and a liquid test was used. Out of 35 wild and commercially grown mushrooms tested, 13 species exhibited mutagenic activity. In the case of the five samples of dried mushrooms, weak mutagenicity could be detected for Auricularia sp. The presence of microsomal enzymes (S-9) reduced the mutagenic effects of all the mushrooms, with the exception of Agaricus abruptibulbus and Cantharellus cibarius, where metabolic activation enhanced the mutagenic activity.

Antimutagenic effects of mushrooms

A heat-resistant factor in ethanol extracts of the fungus Craterellus cornucopioides completely inhibited the mutagenicity of aflatoxin B1, benzo[a]pyrene, the acridine half mustard ICR-191 and 2-nitrofluorene in a forward-mutation system using Salmonella typhimurium TM677 (screening for 8-azaguanine resistance). There was no inhibitory effect on the mutagenic activity of 4-nitroquinoline-N-oxide, methyl methanesulfonate or N-methyl-N'-nitro-N-nitrosoguanidine. Experiments performed to elucidate the mechanism of the antimutagenic effect showed that neither an alteration of cell viability nor an interference with the excision-repair and the inducible SOS-repair system was involved. The conceivable mechanisms for the antimutagenicity of the ethanol extract include direct chemical interaction with the mutagen and/or inhibition of the activation process in the case of the promutagens. The antimutagenic activity of Craterellus cornucopioides is not unique among mushroom species. The ethanol extracts of 6 other mushrooms showed a similar antimutagenic activity.

Comparison of the mutagenic activity of various brands of food grade beef extracts

The mutagenic activity of 9 brands of commercial meat extracts were compared using Ames tester strain TA 98 with hepatic S-9 activation prior to concentration by solvent extraction. In a preincubation test system where 20 mg of intact meat extract preparations were tested per plate, about half of the brands were non-mutagenic whereas the other half increased the spontaneous revertant number by a factor of 2.5-3 (MF). The mutagenic principals could be extracted into methylene chloride under alkaline conditions and the mutagenic activity of these basic organic extracts ranged in potency from a mutation factor of 7-40 (280-1600 revertants) per 2 g equivalents of intact meat extracts in the standard Ames test. A quantitative correlation was obtained between the two trials (intact and extracted samples). The commercial meat extract with the greatest activity contained approximately 70 ng/g of total amino-imidazoquinoline and amino-imidazoquinoxaline compounds while the weakest brand of meat extract contained less than 10 ng/g of these heterocyclic aromatic amines. The human intake of these heterocyclic amines from meat extract in bouillon soups was estimated at maximally 100 ng/day and is approximately 10(3) times less than the estimated total daily intake of all heterocyclic amines which are known to be formed in protein-rich heated foods.