Induction of micronuclei by five pyrethroid insecticides in whole-blood and isolated human lymphocyte cultures

In vitro genotoxicity of polycyclic musk fragrances in the micronucleus test

The synthetic polycyclic musk fragrance compounds galaxolide (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-b enzopyrane), tonalide (7-acetyl-1,1,3,4,4,6-hexamerthyltetraline), celestolide (4-acetyl-1,1-dimethyl-6-tert-butylindane), phantolide (6-acetyl-1,1,2,3,3,5-hexamethylindane), cashmeran (6,7-dihydro-1,1,2,3,3-pentamethyl-4-(5H) indanone) and traseolide (5-acetyl-1,1,2,6-tetramethyl-3-isopropylindane) were examined for their genotoxicity in the micronucleus test (MNT) with human lymphocytes in vitro in the presence and absence of an exogenous metabolizing system containing rat liver S9 and the metabolically competent human hepatoma cell line Hep G2. Compound concentrations were employed up to cytotoxic doses. Galaxolide, tonalide, celestolide, phantolide, cashmeran and traseolide revealed no genotoxicity in the micronucleus test with human lymphocytes and with the human hepatoma cell line Hep G2.

In vivo induction of sister chromatid exchange in mouse bone marrow following oral exposure to commercial formulations of alpha-cyano pyrethroids

In vivo genetic toxicity potential of cypermethrin and deltamethrin, two alpha-cyano pyrethroid insecticides was evaluated through induction of sister chromatid exchange in mouse bone marrow cells. Groups of four healthy, adult, male albino mice were each administered with a single oral dose of 10.6, 21.1 and 32 mg cypermethrin a.i./kg b.w. or 6.6, 13.2 and 20 mg deltamethrin a.i./kg b.w. in peanut oil. For reference, a peanut-oil vehicle control and cyclophosphamide (20 mg/kg, i.p.) positive control group of animals were run in parallel. Sister chromatid exchange (SCE) analysis in bone marrow metaphase chromosomes, 24 h post-treatment, revealed modest induction with statistical significance at the highest test dose of both insecticides as compared to the vehicle control group. Further, the SCE induction by cypermethrin was more prominent than by deltamethrin. Marked induction of SCE frequency by exposure to cyclophosphamide, an alkylating mutagen, lent authenticity to these observations which, together with earlier evidence of mitotic and chromosomal abnormalities by these pyrethroids, substantiated their genetic toxicity potential and susceptibility of mammals to consequent risks.

Assessment of DNA damage induced in vitro by etoposide and two fungicides (carbendazim and chlorothalonil) in human lymphocytes with the comet assay

The effects of two fungicides (carbendazim and chlorothalonil) on the induction of DNA damage in human peripheral blood lymphocytes (human PBL) have been investigated using the single cell gel electrophoresis assay (SCGE assay or comet assay) immediately after a 1-h treatment and after a 24-h post-treatment incubation. The assessment of etoposide (an effective antitumour agent) effects on human PBL in terms of cell viability and dose-DNA damage relationships was made and etoposide selected as a positive control. The results indicate that etoposide induces significant (p < 0.01) dose-dependent DNA damages for concentrations at which the loss of cell viability is low. After a 24-h recuperation period, all observed DNA damages has disappeared. With SCGE assay performed after a 1-h treatment, similar positive results were observed with chlorothalonil alone or in association with carbendazim, without any loss of cell viability. However, a dramatic loss of cell viability was measured after 24 h and was associated with a large proportion of highly damaged cells. In contrast, carbendazim was not cytotoxic on human PBL and did not induced DNA damage using the SCGE assay either immediately after treatment or after a 24-h post-treatment incubation. These results point to the necessity of an adequate evaluation of immediate and long-term cytotoxicity of compounds that are to be assessed by the SCGE assay.

Genotoxicity of nitro musks in the micronucleus test with human lymphocytes in vitro and the human hepatoma cell line Hep G2

The nitro musk compounds musk xylene (1-tert.-butyl-3,5-dimethyl-2,4,6-trinitrobenzene), musk ketone (4-tert.-butyl-3,5-dinitro-2,6-dimethylacetophenone), musk ambrette (1-tert.-butyl-4-methyl-6-methoxy-3,5-dinitrobenzene), musk moskene (1,1,3,3,5-pentamethyl-4,6-dinitroindane) and musk tibetene (1-tert.-butyl-3,4,5-trimethyl-2,6-dinitrobenzene) were tested for their genotoxic activity in the micronucleus test (MN) with human lymphocytes in vitro and the human hepatoma cell line Hep G2. Compound concentrations were employed up to cytotoxic doses. Musk xylene, musk ketone, musk ambrette, musk moskene and musk tibetene revealed no genotoxicity in the micronucleus test with human lymphocytes and with the human hepatoma cell line Hep G2.

Defective transcription-coupled repair of oxidative base damage in Cockayne syndrome patients from XP group G

In normal human cells, damage due to ultraviolet light is preferentially removed from active genes by nucleotide excision repair (NER) in a transcription-coupled repair (TCR) process that requires the gene products defective in Cockayne syndrome (CS). Oxidative damage, including thymine glycols, is shown to be removed by TCR in cells from normal individuals and from xeroderma pigmentosum (XP)-A, XP-F, and XP-G patients who have NER defects but not from XP-G patients who have severe CS. Thus, TCR of oxidative damage requires an XPG function distinct from its NER endonuclease activity. These results raise the possibility that defective TCR of oxidative damage contributes to the developmental defects associated with CS.

Micronuclei induction by 131I exposure: study in hyperthyroidism patients

To evaluate the eventual genetic damage induced by therapeutic exposure to 131I, we have studied the presence of micronuclei (MN) in binucleated peripheral blood lymphocytes from a group of 28 hyperthyroidism patients who received 131I sodium iodide, via oral administration. The study was conducted over time and blood samples were obtained before the treatment, and 1 week, 1 month and 3 months after it. The results obtained indicate a positive relationship between dose and BNMN frequency as calculated by the linear regression coefficient, showing significant increases in the frequency of MN and BNMN (binucleated cells with MN) in the subgroup of patients that received more than 500 MBq. Taking into account that the patients studied were treated with relatively low doses of 131I, our positive results support the view that the MN assay is sensitive enough to monitor the chromosome damage resulting from the exposure.

Spontaneous and mitomycin-C-induced micronuclei in lymphocytes from subjects affected by Turner's syndrome

Peripheral blood lymphocytes from 15 subjects affected by Turner's syndrome (TS) and aged between 2 and 24 years (mean age 10.40 +/- 6.25) were tested to evaluate the spontaneous and Mitomycin-C-induced (MMC) micronucleus (MN) frequency. A group of 15 healthy subjects, in the same range of age (mean age 14.67 +/- 8.30), was also tested as control. As expected, statistically significant differences between spontaneous and MMC-induced MN were found either in TS and in healthy subjects. Unexpectedly, when the two groups of donors were compared, TS subjects showed a lower spontaneous and MMC-induced MN frequency, in comparison with healthy subjects. Cell proliferation kinetic and cytotoxicity were also measured applying the cytokinesis-block proliferation index (CBPI): the results show that MMC, at the employed concentration, does not induce cell cycle delay both in healthy and in TS donors. Whereas, when CBPI from TS and healthy donors were compared, a faster proliferation was found in TS patients in both untreated and MMC-treated cultures.

Lack of micronucleus induction by 'Sobatum' in bone marrow erythrocytes of Swiss mice

The plant Solanum trilobatum is mainly used for asthma, chronic febrile affections and difficult parturition. The active principle (Sobatum) obtained from the petroleum ether extract of the plant was proved as an anticancer agent by in vitro and in vivo experiments. Here, an effort was made to evaluate the induction of micronucleus by the Sobatum in the bone marrow of swiss mice. The micronucleus assay was conducted after 24 and 72 h of second administration of the Sobatum. The first set of experiments (24 h after second administration) consisted of 4 groups with 3 male Swiss albino mice each. The first group (as control) received only dimethyl sulfoxide, the second, third and fourth groups received different doses of the Sobatum (100, 200, 400 mg/kg body weight), and the fifth group (as positive control) received cyclophosphamide (100 mg/kg body weight) by i.p. injection. In the second set of experiment (72 h after the second administration) consisting of 5 groups, the first, as control, received dimethyl sulfoxide, the second, third and fourth groups received different concentrations of the Sobatum (100, 200, 400 mg/kg body weight), and the fifth group as positive control received cyclophosphamide (100 mg/kg body weight). All the animals of the first and second sets of experiment were killed 24 and 72 h after the second medication (2 consecutive days), and bone marrow smears were prepared, stained with May-Grunwald and Giemsa stain, and evaluated for the evidence of micronucleus. The study concluded that the Sobatum fails to influence the induction of micronuclei in bone marrow erythrocytes of mice 24 and 72 h after the second administration, thereby proving that Sobatum to has no cytogenetic toxic potential.

No increase in micronuclei frequency in cultured blood lymphocytes from a group of filling station attendants

Service station attendants are workers that are definitely exposed to petroleum derivatives. Taking into account that this exposure has been considered to possess genotoxic risk, here we present data on the biomonitoring of a group of 50 service station workers and 43 controls. Micronuclei (MN) from peripheral blood lymphocytes has been considered as the genetic endpoint to be studied and, in addition, data on the concentration of aromatic hydrocarbons at the workplace, urinary metabolites and differential white blood cell count have also been analysed. The results obtained indicate no significant differences between petrol station attendants and controls, when the effects of petrol exposure were investigated by differential white blood cell count and analysis of MN frequencies in phytohaemagglutinin-stimulated lymphocytes. Regarding the urinary metabolites, a significant increase in the phenol level was found in the exposed workers.