Chemical mutagenesis testing in Drosophila. V. Results of 53 coded compounds tested for the National Toxicology Program

Acetaldehyde as a Food Flavoring Substance: Aspects of Risk Assessment

The Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) has reviewed the currently available data in order to assess the health risks associated with the use of acetaldehyde as a flavoring substance in foods. Acetaldehyde is genotoxic in vitro. Following oral intake of ethanol or inhalation exposure to acetaldehyde, systemic genotoxic effects of acetaldehyde in vivo cannot be ruled out (induction of DNA adducts and micronuclei). At present, the key question of whether acetaldehyde is genotoxic and mutagenic in vivo after oral exposure cannot be answered conclusively. There is also insufficient data on human exposure. Consequently, it is currently not possible to reliably assess the health risk associated with the use of acetaldehyde as a flavoring substance. However, considering the genotoxic potential of acetaldehyde as well as numerous data gaps that need to be filled to allow a comprehensive risk assessment, the SKLM considers that the use of acetaldehyde as a flavoring may pose a safety concern. For reasons of precautionary consumer protection, the SKLM recommends that the scientific base for approval of the intentional addition of acetaldehyde to foods as a flavoring substance should be reassessed.

Systematic review of the human health hazards of propylene dichloride

Propylene dichloride (PDC) is a chlorinated substance used primarily as an intermediate in basic organic chemical manufacturing. The United States Environmental Protection Agency (EPA) is currently evaluating PDC as a high-priority substance under the Toxic Substances Control Act (TSCA). We conducted a systematic review of the non-cancer and cancer hazards of PDC using the EPA TSCA and Integrated Risk Information System (IRIS) frameworks. We identified 12 epidemiological, 16 toxicokinetic, 34 experimental animal, and 49 mechanistic studies. Point-of-contact respiratory effects are the most sensitive non-cancer effects after inhalation exposure, and PDC is neither a reproductive nor a developmental toxicant. PDC is not mutagenic in vivo, and while in vitro evidence is mixed, DNA strand breaks consistently occur. Nasal tumors in rats and lung tumors in mice occurred after lifetime high-level inhalation exposure. Cholangiocarcinoma (CCA) was observed in Japanese print workers exposed to high concentrations of PDC. However, co-exposures, as well as liver parasites, hepatitis, and other risk factors, may also have contributed. The cancer mode of action (MOA) analysis revealed that PDC may act through multiple biological pathways occurring sequentially and/or simultaneously, although chronic tissue damage and inflammation likely dominate. Critically, health benchmarks protective of non-cancer effects are expected to protect against cancer in humans.

Stellungnahme zu Acetaldehyd als Aromastoff: Aspekte der Risikobewertung

Opinion on acetaldehyde as a flavouring substance: considerations for risk assessment

Acetaldehyde occurs naturally in many foods and is also used as a flavouring due to its fruity aroma. The International Agency for Research on Cancer (IARC) classified acetaldehyde as possibly carcinogenic to humans and, in combination with oral intake via alcoholic beverages, as carcinogenic to humans. Therefore, the question arises whether the use of acetaldehyde as a flavouring agent is still justifiable. The Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) reviewed the scientific basis for health risk assessment of the use of acetaldehyde as a flavouring substance and adopted an opinion. Based on the available data, it is at present not possible to conclude if acetaldehyde is genotoxic and mutagenic in vivo after oral exposure. There is also uncertainty regarding the contribution of acetaldehyde as a flavouring substance to the overall exposure to acetaldehyde. Therefore, a science-based assessment on health risk related to the use of acetaldehyde as a flavouring is not possible at present. Considering the genotoxic potential as well as numerous data gaps that need to be closed for a full risk assessment, the SKLM is concerned about the safety of acetaldehyde as a flavouring substance. For reasons of precautionary consumer protection, the SKLM considers that the use of acetaldehyde as a food additive should be re-evaluated.

RIFM fragrance ingredient safety assessment, p-tolualdehyde, CAS Registry Number 104-87-0

The existing information supports the use of this material as described in this safety assessment. p-Tolualdehyde was evaluated for genotoxicity, repeated dose toxicity, developmental and reproductive toxicity, local respiratory toxicity, phototoxicity, skin sensitization potential, and environmental safety. Data from read-across analog benzaldehyde (CAS # 100-52-7) show that p-tolualdehyde is not expected to be genotoxic. Data from read-across analog cuminaldehyde (CAS # 122-03-2) provided p-tolualdehyde a No Expected Sensitization Induction Level (NESIL) of 1100 μg/cm² for the skin sensitization endpoint. The repeated dose toxicity, developmental and reproductive toxicity, and local respiratory toxicity endpoints were completed using the threshold of toxicological concern (TTC) for a Cramer Class I material, and the exposure to p-tolualdehyde is below the TTC (0.03 mg/kg/day, 0.03 mg/kg/day, and 1.4 mg/day, respectively). The phototoxicity/photoallergenicity endpoints were evaluated based on data from read-across analog 4-ethylbenzaldehyde (CAS # 4748-78-1); p-tolualdehyde is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; p-tolualdehyde was found not to be persistent, bioaccumulative, and toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards, and its risk quotients, based on its current volume of use in Europe and North America (i.e., Predicted Environmental Concentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.

Deriving hazardous concentrations of phenol in soil ecosystems using a species sensitivity distribution approach

Phenol is widely used in many industries, and chemical accidents involving phenol have frequently occurred around the world, resulting in the investigation of phenol toxicity in humans, mammals, and aquatic organisms. However, very few studies have investigated phenol toxicity in terrestrial ecosystems. Therefore, we investigated the acute and chronic toxicity of phenol using various soil organisms, including Chlamydomonas reinhardtii, Chlorococcum infusionum, Folsomia candida, Oryza sativa, Raphanus sativus, Pinus densiflora, and Eisenia fetida. The data obtained were used to calculate hazardous concentrations for 5% of species (HC₅) for phenol based on a species sensitivity distribution approach. The acute and chronic soil HC₅ values for phenol were estimated to be 18.4 and 0.3 mg kg^-1, respectively. To the best of our knowledge, this is the first study to conduct battery testing and calculate hazardous concentrations to assess the risk posed by phenol in terrestrial ecosystems. The results can be used to establish standards or strategies to protect terrestrial environments against unintended phenol contamination.

Final Report On the Safety Assessment of Hc Yellow No. 4

HC Yellow No. 4 is a colorant for use mostly in hair dyes and colors, but also in a few hair tints. Concentrations at which the ingredient is used range from 0.1 % to 1.0%. Confusion has existed regarding the proper structure for this ingredient, but was resolved through additional analysis; the correct CAS number is 59820-43-8. Commercially available HC Yellow No. 4 may contain a nitroaniline impurity. Percutaneous absorption studies using commercial products containing 1% HC Yellow No. 4 found little absorption. Body weight decreases were noted in short-term oral toxicity studies and in a subchronic oral toxicity study. HC Yellow No. 4 did not produce irritation, sensitization, or photosensitization in animal tests (primarily using guinea pigs). In some feeding studies, fetal toxicity was observed, but no such effect was found in other feeding studies. HC Yellow No. 4 was mutagenic in several assays, but no evidence of carcinogenesis was found in oral or dermal studies. Two repeated insult patch tests, totalling over 200 human volunteers, found no sensitization reactions. While there was concern expressed over the reproduction and developmental toxicity found in feeding studies, such adverse responses would not be expected from the use of this ingredient in hair coloring products because so little HC Yellow No. 4 is absorbed. The presence of a low level of nitroaniline derivative impurity (0.3 to 7%) is not considered to present a human health risk because the products containing HC Yellow No. 4 are used in a brief and discontinuous manner, followed by rinsing. On the basis of the available data, therefore, it is concluded that HC Yellow No. 4 is safe as a hair colorant in the present practices of use.

Determination of two mercapturic acids related to crotonaldehyde in human urine: influence of smoking

Crotonaldehyde, an αβ-unsaturated aldehyde, and a potent alkylating agent, is present in many foods and beverages, ambient air and tobacco smoke. A previous study indicated that two metabolites, 3-hydroxy-1- methylpropylmercapturic acid (HMPMA) and 2-carboxy1-1-methylethylmercapturic acid (CMEMA), were excreted in rat urine after subcutaneous injection of crotonaldehyde. Herein, we report the development of a method based on liquid chromatography with tandem mass spectrometry (LC-MS/MS) and deuterated analytes as internal standards, for the determination of HMPMA and CMEMA in human urine. The limits of quantification of the method were 92 and 104 ng/mL for HMPMA and CMEMA, respectively. The calibration curves for both compounds were linear up to 7500 ng/mL with R2 >0.99. It was found that cigarette smokers excreted about three to five-fold more HMPMA, and only slightly elevated amounts of CMEMA, in their urine compared to non-smokers. In smokers, we also found significant correlations between the urinary excretion levels of HMPMA (but not CMEMA) and several markers of exposure for smoking, including the daily cigarette consumption, carbon monoxide in exhaled breath, salivary cotinine, and nicotine plus five of its major metabolites in urine. Smoking cessation or switching from smoking conventional cigarettes to experimental cigarettes with lower crotonaldehyde delivery led to significant reductions of urinary HMPMA excretion, but not CMEMA excretion. Alcohol consumption did not influence either urinary HMPMA or CMEMA excretion. We conclude that HMPMA is a potentially useful biomarker for smoking-related exposure to crotonaldehyde.

Determination of Hepatotoxicity and Its Underlying Metabolic Basis of 1,2-Dichloropropane in Male Syrian Hamsters and B6C3F1 Mice

1,2-Dichloropropane (1,2-DCP) has recently been reclassified from not classifiable as to its carcinogenicity to humans (Group 3) to carcinogenic to humans (Group 1) by the International Agency for Research on Cancer. This was based on the findings of epidemiological studies in Japan that occupational exposure to paint stripers containing 1,2-DCP was associated with increased cholangiocarcinomas. It is known that 1,2-DCP is negative for cholangiocarcinogenicity in rats and mice. However, its toxicity and carcinogenicity has not been examined in hamsters and little is known about the regulation of its metabolism in hamsters. The purpose of this study was to determine the hepatobiliary toxicity of 1,2-DCP in hamsters and to characterize and compare the altered patterns of hepatic xenometabolic enzymes in hamsters and mice. Male Syrian hamsters and male B6C3F1 mice were treated with various doses of 1,2-DCP for 4 h or 3 days or 4 weeks. These experiments demonstrated that a high dose of 1,2-DCP induced centrilobular hepatocellular necrosis in hamsters. CYP2E1 is possibly the key enzyme responsible for bioactivation and the consequent hepatocytotoxicity of 1,2-DCP, and GSH conjugation catalyzed by GST-T1 may exert a cytoprotective role in hamsters and mice. Notably, the expression pattern of GST-T1 in bile duct epithelial cells differed between hamsters and mice: GST-T1 was expressed in bile duct epithelial cells of mice but not hamsters. This indicates that responses to 1,2-DCP in the bile duct of hamsters might differ from that of mice, and suggests that long-term studies are necessary to clarify the chalangiocarcinogenicity of 1,2-DCP in hamsters, though no biliary toxicity was observed in the present short-term experiments.

Development of three stable isotope dilution assays for the quantitation of (E)-2-butenal (crotonaldehyde) in heat-processed edible fats and oils as well as in food

Three stable isotope dilution assays (SIDAs) were developed for the quantitation of (E)-2-butenal (crotonaldehyde) in heat-processed edible fats and oils as well as in food using synthesized [¹³C₄]-crotonaldehyde as internal standard. First, a direct headspace GC-MS method, followed by two indirect methods on the basis of derivatization with either pentafluorophenylhydrazine (GC-MS) or 2,4-dinitrophenylhydrazine (LC-MS/MS), was developed. All methods are also suitable for the quantitation of acrolein using the standard [¹³C₃]-acrolein. Applying these three methods on five different types of fats and oils varying in their fatty acid compositions revealed significantly varying crotonaldehyde concentrations for the different samples, but nearly identical quantitative data for all methods. Formed amounts of crotonaldehyde were dependent not only on the type of oil, e.g., 0.29-0.32 mg/kg of coconut oil or 33.9-34.4 mg/kg of linseed oil after heat-processing for 24 h at 180 °C, but also on the applied temperature and time. The results indicated that the concentration of formed crotonaldehyde seemed to be correlated with the amount of linolenic acid in the oils. Furthermore, the formation of crotonaldehyde was compared to that of its homologue acrolein, demonstrating that acrolein was always present in higher amounts in heat-processed oils, e.g., 12.3 mg of crotonaldehyde/kg of rapeseed oil in comparison to 23.4 mg of acrolein/kg after 24 h at 180 °C. Finally, crotonaldehyde was also quantitated in fried food, revealing concentrations from 12 to 25 μg/kg for potato chips and from 8 to 19 μg/kg for donuts, depending on the oil used.

Assessment of cytotoxic and apoptotic effects of benzaldehyde using different assays

Benzaldehyde (BA) occurs naturally in a number of plants, including cherry, fig and peach fruit and carnation flowers at therapeutic doses. In addition, it is used in cosmetics, personal care products and food as a preservative. In this study, we aimed to determine the cytotoxic and apoptotic effects of different concentrations of BA on cultured human lymphocytes using lactate dehydrogenase assay, cell proliferation (water-soluble tetrazolium salts-1) assay and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) test (apoptotic test) as a group of cytotoxicity tests at 6th and 24th h on human lymphocyte cell culture. The cytotoxicity increased when cells were treated with 10, 25 and 50 μg/mL concentrations of BA ( p < 0.05). Moreover, treatment of the cells with the same concentrations significantly decreased the cell number at the 6th and 24th hours ( p < 0.05). TUNEL assay results also show that the concentration of BA at 10, 25 and 50 μg/mL caused DNA damage significantly ( p < 0.05). According to our results, the toxic and genotoxic effects of BA have to be further evaluated before using in cosmetic and food products.

Mutagenic/recombinogenic effects of four lipid peroxidation products in Drosophila

The human diet is an important factor in the development of different diseases. Lipid peroxidation during frying in edible vegetable liquid oils of food components is a mechanism leading to the formation of free radicals. Such radicals induce tissue damage and are implicated in diverse pathological conditions, including aging, atherosclerosis, brain disorders, cancer, lung disorders and various liver disorders. In the present study, we decided to investigate the genotoxic effects of four lipid peroxidation products in the in vivo Drosophila wing somatic mutation and recombination test. In this test, point mutation, chromosome breakage and mitotic recombination produce single spots; while twin spots are produced only by mitotic recombination. Drosophila is a suitable eukaryotic organism for mutagenicity studies and also its metabolism is quite similar to that of mammalians. Since conflicting data exist on the possible risk of several lipid peroxidation products for humans, we have selected four of them, namely acrolein, crotonaldehyde, 4-hydroxy-hexenal (4-HHE) and 4-oxo-2-nonenal (4-ONE). Especially at the highest concentrations tested all exert both mutagenic and recombinogenic effects in the Drosophila SMART assay, showing a direct dose-effect relationship. This is the first study reporting genotoxicity data in Drosophila for these compounds.

Subacute oral and dermal toxicity of tert-butyl hydroperoxide in Fischer F344/N rats and B6C3F1 mice

Tert-butyl hydroperoxide (TBHP) is a catalyst frequently used in oxidation and sulfonation reactions in the plastics industry. Since the toxicological evaluation of TBHP remains unknown, the National Toxicology Program (NTP) designed studies to characterize and compare TBHP toxicity by the dermal and oral (gavage) routes in male and female Fischer 344 rats and B6C3F1 mice in 14-day exposures. Rats and mice were administered TBHP at 22, 44, 88, 176 or 352 mg/kg in 0.5% aqueous methylcellulose for the gavage studies. In the dermal studies, mice were administered the same doses as above, while rats were administered four doses (22, 44, 88, 176 mg/kg) in 50% aqueous acetone. Results from the gavage studies revealed treatment-related decreases in survival in male rats and body weights in both male and female rats in the 352 mg/kg group. Clinical signs included post-treatment lethargy, thinness, abnormal breathing, ruffled fur, and/or ataxia which occurred sporadically. The male mice showed a statistically significant decrease in body weight in the 44, 88, 176, and 352 mg/kg groups. The major target organs of toxicity were the forestomach in male and female rats and mice, and the esophagus in male and female rats and in male mice. In addition, there was an increase in the absolute and relative liver weight in female mice with hepatocellular hypertrophy in the top-dose group only. Results from spin trapping experiments revealed the presence of electron paramagnetic resonance signals from radical adducts in the blood and organic extracts of the liver and kidneys of rats treated by gavage with 176 mg/kg TBHP, suggesting the involvement of free- radical generation. The no observed adverse effect level (NOAEL) was considered to be 22 mg/kg in rats and male mice, and 44 mg/kg in female mice. In the dermal studies, there was no effect on survival, body weight, or organ weights in either rats or mice. TBHP administration at the site of application resulted in dermal irritation, hyperkeratosis, hyperplasia, and/or inflammation of the epidermis and inflammation of the dermis at 176 mg/kg and above in male and female rats. Dermal irritation at the site of application was noted in all the mice exposed to 352 mg/kg TBHP. Histopathological lesions in the epidermis and dermis were seen in the 88-352 mg/kg males and in the 176-352 mg/kg females. The NOAEL was found to be 88 mg/kg for male rats and female mice, and 44 mg/kg for female rats and male mice. In conclusion, these studies demonstrate that TBHP is metabolized to free radicals and is a contact irritant affecting skin by the dermal route of exposure, and forestomach and esophagus by oral administration. There was no evidence of systemic absorption by the dermal route of exposure based on lack of pathological findings (Supported by National Institute of Environmental Health Sciences Contract No. N01-ES-65406).

Genotoxicity of crotonaldehyde in the bone marrow and germ cells of laboratory mice

Genotoxicity of crotonaldehyde was evaluated by employing bone marrow and spermatocyte chromosomal aberration and dominant lethal mutation assays in Swiss albino mice. For bone marrow chromosomal aberration assay, animals were treated with 0.2ml olive oil containing 8, 16 and 32microl kg b.w. of crotonaldehyde for 6, 12 and 24h through single intraperitoneal injection. Treatment induced dose-dependent and statistically significant decrease in mitotic index and increase in chromosome aberrations per cell (CAs/cell excluding gaps and stickiness and pulverizations) and percent aberrant metaphase (excluding gaps) in the bone marrow cells at 6, 12 and 24h after treatment. For spermatocyte chromosomal aberration assay, male mice were treated with 8, 16 and 32microl/kg b.w. of crotonaldehyde for 24h through single intraperitoneal injection. The percentage of the induced chromosome aberrations in diakinesis-metaphase-I cells showed dose-dependent increase. For dominant lethal mutation assay, adult male mice were injected intraperitoneally with 0.2ml olive oil containing crotonaldehyde at the rate of 8, 16 and 32microl/kg b.w. for 5 consecutive days. The negative control animals received 0.2ml olive oil as above. In the dominant lethal mutation assay after the last dose, the treated males were allowed to mate with untreated virgin females. The mating continued for 5 consecutive weeks. At pregnancy days 14-16, the females were killed and uterine contents were examined for live and dead implants. Treatment of mice resulted in statistically significant decrease in the fertility indices and total number of implants per female. Statistically significant decrease in the number of live implants per female and increase in the number of dead implants per female were recorded in females mated with males during 8-14 and 15-21 and 22-28 days post-treatment mating. Crotonaldehyde treatment of males induced appreciably higher frequencies of dominant lethal mutation during 8-14, 15-21 and 22-28 days post-treatment mating periods. Percent dominant lethal mutation increased concomitantly with the dose. Dominant lethality was maximum in females mated with males treated with 5x32microl/kg b.w. during the 15-21 days post-treatment mating. The overall result suggests a positive dose-response relationship between treatment and induction of chromosomal aberrations in the somatic and germ cells and dominant lethal mutation in the germ cells.

Antioxidant enzyme activities and lipid peroxidation products in heart tissue of subacute and subchronic formaldehyde-exposed rats: a preliminary study

OBJECTIVE

The aim of this experimental study was to evaluate the oxidant/antioxidant status and lipid peroxidation in the heart of rats exposed to formaldehyde (FA) inhalation for four weeks (subacute) or 13 weeks (subchronic) continuously.

METHODS AND RESULTS

Sixty Wistar albino rats were divided into six groups randomly (ten in each group). The first and second groups were used as subacute and subchronic control groups. FA gas was generated from paraformaldehyde and pumped to a closed glass chamber. Rats were exposed to atmosphere containing 10 and 20 ppm FA (8 h/day, five days per week) during a four and 13 weeks period. After heart tissues were obtained and homogenized, thiobarbituric acid-reactant substances (TBARS) and nitric oxide (NO) levels, as well as superoxide dismutase (SOD) and catalase (CAT) activities, were measured. There were statistically significant findings in SOD and CAT activities in the study groups compared to the control group. Heart tissue SOD level was increased in the group exposed to subacute 10 and 20 ppm FA inhalation compared to the control group (P < 0.011 and <0.0001). In addition, heart tissue SOD level was increased in the group exposed to subchronic 10 and 20 ppm FA inhalation compared to the corresponding control group (P < 0.001). On the other hand, there were statistically significant decreases in CAT activity in subacute 10 and 20 ppm groups compared to the corresponding control group (P < 0.012 and < 0.039, respectively). Although not significant, TBARS levels were increased in both subacute 10 ppm (P = 0.100) and subchronic 20 ppm (P = 0.053) groups compared to their corresponding control groups. Tissue NO levels were unchanged upon FA inhalation. In the correlation analyses, a meaningful relationship between SOD and CAT activities in subchronic 10 ppm group (r = -0.685, P < 0.029); SOD activity and TBARS level in subchronic 20 ppm group (r = -0.675, P < 0.032); and CAT activity and NO level in subchronic 20 ppm group (r = -0.810, P < 0.005) were found.

CONCLUSION

From the findings of our study, it can be interpreted that subacute and subchronic FA inhalation may stimulate oxidative stress and thus, some secondary toxic effects in cardiac cells and tissue. This increase in the oxidative stress could not induce lipid peroxidation in the membranous structure of cardiac cells. An increased SOD enzyme activity was thought to be secondary to decreased CAT activity, as a compensation mechanism, preventing heart tissue from destruction induced by FA.

In vivo evaluation of induction of abnormal sperm morphology in mice by an unsaturated aldehyde crotonaldehyde

Crotonaldehyde, a highly reactive unsaturated aldehyde is used for the manufacture of sorbic acid, synthesis of butyl alcohol, butylaldehyde, quinaldine, thiophenes, pyridines, dyes, pesticides, pharmaceuticals, rubber antioxidants, chemical warfare agents, etc. and also occurs naturally in meat, fish, in many fruits and vegetables, bread, cheese, milk, beer, wine and liquors. Human exposure to crotonaldehyde occurs from both man-made and natural sources. No human data was located describing carcinogenicity associated with crotonaldehyde exposure. In the present study we have evaluated whether or not exposure to crotonaldehyde results in a significant increase in the frequency of abnormal sperm heads in male Swiss albino mice. Adult male mice were treated with 8, 16 and 32 microl/kg b.w. of crotonaldehyde as a single intraperitoneal injection. The animals were killed 1, 3 and 5 weeks after treatment. Five animals were sacrificed per dose and time tested. Crotonaldehyde induced dose related increase in the percentage of abnormal sperm heads. Statistically significant increase in percentage of abnormal sperm heads was recoded at 16 and 32 microl/kg b.w. after 1 and 3 weeks of treatment and only at 32 microl/kg b.w. after 5 weeks of treatment.

The FEMA GRAS assessment of benzyl derivatives used as flavor ingredients

This publication is the eighth in a series of safety evaluations performed by the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA). In 1993, the panel initiated a comprehensive program to re-evaluate the safety of more than 1700 GRAS flavoring substances under conditions of intended use. Elements that are fundamental to the safety evaluation of flavor ingredients include exposure, structural analogy, metabolism, pharmacokinetics and toxicology. Flavor ingredients are evaluated individually and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of benzyl derivatives as flavoring ingredients is evaluated. The group of benzyl derivatives was reaffirmed as GRAS (GRASr) based, in part, on their self-limiting properties as flavoring substances in food; their rapid absorption, metabolic detoxication, and excretion in humans and other animals, their low level of flavor use, the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels determined from subchronic and chronic studies and the lack of significant genotoxic and mutagenic potential. This evidence of safety is supported by the fact that the intake of benzyl derivatives as natural components of traditional foods is greater than their intake as intentionally added flavoring substances.

Analysis of genotoxicity and the carcinogenic mode of action for ortho-phenylphenol

Ortho-phenylphenol (OPP) and its sodium salt (SOPP) are commercial products that have wide human exposure and have been shown in several studies to be rodent carcinogens. Genetic toxicology data were assessed in an attempt to understand the carcinogenic mode of action of OPP and SOPP. More than 130 studies were evaluated to determine if OPP, SOPP, or any of their enzymatic or nonenzymatic breakdown products react directly with DNA to induce mutation, changes in chromosome structure or number, DNA repair, or nonspecific DNA damage including strand breakage or covalent binding. The genotoxicity databases for OPP and SOPP are not only large but heterogeneous, requiring weight-of-evidence methods to arrive at a conclusion regarding their genotoxic properties and potential. Evidence derived from the available studies leads to the conclusion that study results showing OPP/SOPP directly interacting with DNA are equivocal. Clastogenicity was the most consistent type of genetic toxicity produced by OPP/SOPP (and their break-down products) and was consistently associated with other intracellular preneoplastic toxicity produced at super-threshold concentrations. The weight of evidence from the combined database supports the hypothesis that OPP/SOPP-induced DNA damage is a threshold-dependent response associated with target tissue toxicity, most likely induced by their breakdown products phenylhydroquinone and phenylbenzoquinone. It is possible that this threshold-dependent clastogenicity could contribute to the carcinogenic mode of action for OPP or SOPP.

Fragrance material review on cinnamaldehyde

A toxicologic and dermatologic review of cinnamaldehyde when used as a fragrance ingredient is presented.

Increased spontaneous DNA damage in Cu/Zn superoxide dismutase (SOD1) deficientDrosophila

The superoxide dismutases (SODs) protect oxygen-using cells against reactive oxygen species, the potentially toxic by-products of respiration, oxidative metabolism, and radiation. We have previously shown that genetic disruption of CuZn SOD (SOD1) in Drosophila imparts a recessive phenotype of reduced lifespan, infertility, and hypersensitivity to oxidative stress. We now show that the absence of SOD1 increases spontaneous genomic damage. The increase in spontaneous mutation rate occurs in SOD1-null mutants in somatic cells as well as in the germ line. Further, we show that specific DNA repair-defective mutations, which are easily tolerated in SOD1+flies, lead to high mortality when introduced into the SOD1-null homozygous mutant background.Key words: Drosophila melanogaster, superoxide dismutase, mutations, germ and somatic cells, lethal and somatic mutations, reactive oxygen.