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

Evaluation of Genotoxic Effects in Human Fibroblasts after Intermittent Exposure to 50 Hz Electromagnetic Fields: A Confirmatory Study

The aim of this investigation was to confirm the main results reported in recent studies on the induction of genotoxic effects in human fibroblasts exposed to 50 Hz intermittent (5 min field on/10 min field off) sinusoidal electromagnetic fields. For this purpose, the induction of DNA single-strand breaks was evaluated by applying the alkaline single-cell gel electrophoresis (SCGE)/comet assay. To extend the study and validate the results, in the same experimental conditions, the potential genotoxicity was also tested by exposing the cells to a 50 Hz powerline signal (50 Hz frequency plus its harmonics). The cytokinesis-block micronucleus assay was applied after 24 h intermittent exposure to both sinusoidal and powerline signals to obtain information on cell cycle kinetics. The experiments were carried out on human diploid fibroblasts (ES-1). For each experimental run, exposed and sham-exposed samples were set up; positive controls were also provided by treating cells with hydrogen peroxide or mitomycin C for the comet or micronucleus assay, respectively. No statistically significant difference was detected in exposed compared to sham-exposed samples in any of the experimental conditions tested (P > 0.05). In contrast, the positive controls showed a statistically significant increase in DNA damage in all cases, as expected. Accordingly, our findings do not confirm the results reported previously for either comet induction or an increase in micronucleus frequency.

Protective effect of apigenin on radiation-induced chromosomal damage in human lymphocytes

The potential use of flavonoids as a radioprotector is of increasing interest because of their high antioxidant activity and abundance in the diet. The aim of this study is to examine genotoxic and radioprotective effects of one of the most common flavonoids, apigenin, on radiation-induced chromosome aberrations in human lymphocytes. The cytokinesis-block micronucleus (CBMN) assay was used to evaluate such effects of apigenin. Blood samples were collected from two non-smoking healthy male volunteers who had no history of previous exposure to other clastogenic agents. Isolated lymphocytes were cultured. There were two tubes per concentration for all treatments. To evaluate the genotoxicity of apigenin, cells were first treated with different concentrations of apigenin (0, 2.5, 5, 10 and 25 microg/mL) at 24 h after culture initiation, followed by cytochalasin-B (Cyt-B) treatment (3 microg/mL) and cell harvest at 44 and 72 h, respectively. Secondly, to investigate the radioprotective effect, cell cultures were exposed to different concentrations of apigenin as described above for 30 min before being irradiated to 2 Gy of 137Cs gamma rays (at a dose rate of 0.75 Gy/min). In all instances, the frequency of MN was scored in binucleated (BN) cells. The nuclear proliferation index also was calculated. We did not detect an increase in the frequency of MN in non-irradiated human lymphocyte cultures treated with 2.5, 5.0 or 10 microg/mL apigenin; although, we did observe an increase in cultures treated with 25 microg/mL apigenin (the highest concentration of apigenin used in our study). We also observed a significant increase in the frequency of MN in irradiated cells overall; however, the frequency was decreased as the concentration of apigenin increased, suggesting a radioprotective effect. These findings provide a basis for additional studies to help clarify the potential use and benefit of apigenin as a radioprotector.

Evaluation of cytogenetic effects of lambda-cyhalothrin on Wistar rat bone marrow by gavage administration

In this study, a synthetic pyrethroid insecticide, lambda-cyhalothrin (LCT), was administered to adult female albino rats (Wistar rats) by gavage dose of 6.12, 3.06, 0.8 mg/kg b.w. repeated for 13 days at 48 h intervals. The cytotoxic and genotoxic effects of LCT were investigated in bone marrow cells, using the structural chromosomal aberration (SCA) and micronucleus (MN) test systems. Mitomycin C (MMC) was also used as positive control (2mg/kg b.w.). All the doses of LCT increased the number of SCAs and the frequency of micronucleated erythrocytes, with respect to the control group. Only the highest dose of LCT significantly increased the MN frequency compared with control (P < 0.01). It was also observed that LCT caused a significant decrease in the number of polychromatic erythrocytes compared with controls (p < 0.001). These observations indicate the in vivo suspectibility of mammals to the genetic toxicity and cytotoxicity potential of LCT.

Induction of micronuclei by lambda-cyhalothrin in Wistar rat bone marrow and gut epithelial cells

We have investigated the genotoxicity of lambda-cyhalothrin (LCT) (CAS registry No. 91465-08-06), a pyrethroid insecticide, in bone marrow cells and in colonic crypt epithelial cells of groups of four rats per dose treated in vivo by gavage at doses of 0.8, 3.06 and 6.12 mg/kg body weight (body wt). We measured genotoxicity using the micronucleus (MN) assay, scoring 2000 polychromatic erythrocytes (PCEs) per animal for bone marrow and 1000 colonic crypt epithelial cells per animal for the colon. We assessed cytotoxicity in bone marrow by calculating the ratio of PCEs to normochromatic erythrocytes, and in the colonic crypt epithelium by observing the frequency of binucleate cells and the mitotic index in 1000 cells. Apoptosis in colonic crypt epithelial cells was measured by observing the frequency of karyorrhexis and karyolysis in 1000 cells. We found that LCT induced a statistically significant dose-related increase in MN formation in the bone marrow and the colonic crypt. The colonic epithelium was more sensitive to the clastogenic effects of LCT than the bone marrow as judged by the significantly higher frequencies of MN in the colon than in the bone marrow at doses of 3.06 and 6.12 mg/kg body wt.

Oestradiol potentiates the effects of certain pyrethroid compounds in the MCF7 human breast carcinoma cell line

Pyrethroids are the most widely used insecticides for indoor pest control, so human exposure to them is common. The main target of pyrethroids is the nervous system, but their endocrine disrupting capabilities may also be of toxicological concern. In the present study, the proliferation of the breast cancer cell line, MCF7, was studied after a 7-day exposure to various concentrations of pyrethrin, permethrin and cypermethrin. The effects of oestradiol and the combined effects of oestradiol (0.10 nM) and pyrethroids (0.1-100 microM) on MCF7 cell proliferation were also evaluated. Proliferation and cell toxicity were studied by measuring the ATP content with a luminescence method, and mitochondrial metabolic enzyme activity with the WST-1 test. In the ATP test, low concentrations (0.1-1 microM) of pyrethroids in co-exposure with oestradiol caused a clear statistically significant increase in the proliferation of MCF7 cells. This was evident when compared to the proliferative effect caused by 0.1 nM oestradiol alone. High concentrations were cytotoxic, and the greatest cell toxicity was that of cypermethrin, which has a cyano group in its molecular structure.

Genotoxicity studies on the antimicrobial drug sulfamethoxazole in cultured human lymphocytes

The genotoxicity of the antimicrobial drug sulfamethoxazole was evaluated in cultured human peripheral blood lymphocytes. The frequencies of sister-chromatid exchange (SCE) and micronuclei (MN) were scored as genetic endpoints. Both tests cover a wide range of induced genetic damage such as primary DNA damage, clastogenicity and aneugenicity. Cultures were set up with blood samples from two healthy donors and the treatment was done with different sulfamethoxazole concentrations ranging from 10 to 500 microg/ml. From the results obtained it appears that this drug is able to induce weak genotoxic effects, as revealed by the slight increase in the SCE and MN frequencies, at least at one of the two highest concentrations tested. However, the results of the SCE assay should be interpreted with caution because the increase is just significant. In addition, cyotoxic/cytostatic effects of sulfamethoxazole were revealed by a decrease in the proliferative rate index (PRI) and in the cytokinesis block proliferation index (CBPI).

Evaluation of micronucleus induction in a Chilean population environmentally exposed to arsenic

In the present study we have evaluated whether or not environmental exposure to arsenic in ground drinking-water results in a significant increase in the frequency of micronuclei (MN) in peripheral blood lymphocytes. Thus, 106 individuals from the Antofagasta region (North Chile), together with 111 individuals from the area of Concepción, were used in this investigation. In the Antofagasta area, arsenic levels in drinking-water as high as 0.750 mg/L were measured. In Concepción, located about 2500 km towards the south and used as reference area, arsenic levels in tap water were as low as 0.002 mg/L. The total content of arsenic in fingernails was determined as a biomarker of individual exposure. The cytogenetic results obtained in this study indicate that in the exposed group the overall frequency of binucleated micronucleated cells (BNMN) is higher than in the reference group, the difference being statistically significant. In addition, no differences were found between the exposed and the reference groups, regarding the cytokinesis-block proliferation index (CBPI). No association was observed between BNMN and arsenic content in water or arsenic in fingernails. On the other hand, when the exposed group was divided according to their Atacameno or Caucasian ethnicity, no significant differences were observed between them. In addition, as usually found in other human biomonitoring studies, sex and age are factors that modulate the frequency of MN in both exposed and reference populations.

Effects of pesticides on human peripheral lymphocytes in vitro: induction of DNA damage

Because of the widespread use of pesticides for domestic and industrial applications the evaluation of their genotoxic effects is of major concern to public health. Although various experimental data have provided evidence that pesticides can possess genotoxic properties in animals and in in vitro test systems after acute and chronic exposure, the information on the genotoxic effects of some of pesticides is limited and inconsistent. In the present study, the genotoxic potential of commonly used pesticides (i.e., dimethoate and methyl parathion from the organophosphate class, propoxur and pirimicarb from carbamates, and cypermethrin and permethrin from pyrethroids) have been evaluated. The genotoxic effects of these substances were examined using the single cell gel electrophoresis (comet) assay in freshly isolated human peripheral lymphocytes. The cells were incubated with 10, 50, 100 and 200 microg/ml concentrations of the test substances for 0.5 h at 37 degrees C and DNA damage was compared with that obtained in lymphocytes from the same donor not treated with substances. Hydrogen peroxide, 100 microM, was used as a positive control. Within the concentration ranges studied, no significant cytotoxic effects were observed. Dimethoate and methyl parathion at 100 and 200 microg/ml; propoxur at 50, 100 and 200 microg/ml, and pirimicarb, cypermethrin and permethrin at 200 microg/ml significantly increased DNA damage in human lymphocytes.

Genotoxic evaluation of the antimalarial drug, fansidar, in cultured human lymphocytes

Fansidar (pyrimethamine-sulfadoxine) has been used extensively worldwide for the treatment of chloroquine resistant Plasmodium falciparum malaria, toxoplasmosis and Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome. Because of the wide usage of pyrimethamine-sulfadoxine in developing countries and the lake of information from open literature and reports from manufacturers about the genotoxicity of such antimalarial drug, the present work was suggested. The possible genetic toxicity of fansidar has been evaluated in human peripheral blood lymphocyte cultures. The frequencies of sister-chromatid exchanges (SCE) and micronuclei (MN) were scored as genetic endpoints. Both tests covering a wide range of induced genetic damage as primary DNA damage, clastogenicity and aneugenicity. Cultures were set up by using blood samples from two healthy donors and the treatment was done using different fansidar concentrations ranging from 1:20 to 10:200 microg/ml. From our results, it appears that this drug is able to induce moderate genotoxic effects, as revealed by the increases found in SCE and MN frequencies in cultures from the two donors at the two highest concentrations tested (5:100 and 10:200 microg/ml). In addition, cyotoxic/cytostatic effects of fansidar were revealed by a decrease in the proliferative rate index (PRI) and in the cytokinesis block proliferation index (CBPI). Our findings suggest that the use of this drug should be restricted to situations where other antimalarial drugs cannot be used. The drug should never be given to pregnant women.

Functional consequences of ATM sequence variants for chromosomal radiosensitivity

The ATM [for ataxia-telangiectasia (A-T) mutated] protein plays a key role in the detection and cellular response to DNA double-strand breaks. Several single-nucleotide polymorphisms (SNPs) have been described in the ATM gene; however, their association with cancer risk or radiosensitivity remains to be fully established. In this study, the functional consequences of specific ATM SNPs on in vitro radiosensitivity, as assessed by micronuclei (MN) formation, were measured in lymphoblastoid cell lines established from 10 breast cancer (BC) patients carrying different ATM missense SNPs, six A-T patients, six A-T heterozygotes (A-T het), and six normal individuals. The BC, A-T het, and A-T cell line groups showed significantly higher mean levels of MN formation after exposure to ionizing radiation (IR) than did the group containing normal cell lines, with similar levels in the BC and A-T het groups. Within the BC lines studied, the group composed of the six carrying the linked 2572T>C (858F>L) and 3161C>G (1054P>R) variants had a higher level of MN after IR exposure compared to that observed in the remaining four BC or in the normal cell lines. This increase was not related to the constitutive ATM mRNA level, which was similar in these BC and the normal cell lines. Our results indicate that alterations in the ATM gene, including the presence of heterozygous mutations and the 2572C and 3161G variant alleles, are associated with increased in vitro chromosomal radiosensitivity, perhaps by interfering with ATM function in a dominant-negative manner.

In vitro antigenotoxic potential of acitretin in human lymphocytes treated with the antineoplastic alkylating agent ASE (NSC-71964)

Acitretin is widely used in the systemic treatment of severe forms of psoriasis and other skin disorders. ASE, namely 3beta-hydroxy-13alpha-amino-13,17-seco-5alpha-androstan-17-oic-13,17-lactam-p-bis(2-chloro-ethyl)amino phenylacetate (AzaSteroidalEster, NSC-71964), is an alkylating agent with antineoplastic activity and mutagenic properties. The aim of this study was to investigate the possible genotoxic and/or antigenotoxic effects of acitretin in human lymphocyte cultures in vitro, using sister chromatid exchange (SCE) and cytokinesis-blocked micronucleus (CBMN) assays. Micronucleus (MN) analysis was achieved in combination with fluorescence in situ hybridization (FISH), using an alpha-satellite DNA pancentromeric probe. It was found that acitretin alone demonstrated no clastogenic or aneugenic activity. However, simultaneous incubation of lymphocyte cultures with ASE and acitretin resulted in a reduction of ASE-induced SCEs. For MN analysis lymphocytes were treated with ASE and acitretin at 21 and 41 h after culture initiation, corresponding to G1 and G2 phases, respectively, and lasted until cell harvest. Acitretin caused a decrease in ASE-induced MN when treatment of cells started at 41 h, but exerted no effect on them when treatment started at 21 h. These findings suggest that acitretin exerts antigenotoxic effects in human lymphocyte cultures, the expression of which may be related to the cycle phase of the cells upon onset and duration of the treatment, at least as far as MN frequency is concerned.

Genotoxicity testing of the furylethylene derivative 1-(5-bromofur-2-yl)-2-bromo-2-nitroethene in cultured human lymphocytes

The genotoxic potential of the compound 1-(5-bromofur-2-yl)-2-bromo-2-nitroethene (G-1) was evaluated in peripheral blood lymphocytes cultured in vitro, at concentrations ranging from 1 to 20 microg/ml. Micronuclei (MN) and sister-chromatid exchanges (SCE) were scored as biomarkers of genotoxic effects. To detect the role of metabolic enzymes on the genotoxicity of this furylethylenic derivative, cultures for MN and SCE demonstrations were treated for 3 h with and without the S9 microsomal fraction as well as for 48 h without S9. Under the conditions of the study, the test agent did not induce significant increases in the frequency of micronucleated cells, irrespective of the presence/absence of the metabolic fraction. Nevertheless, a slight/moderate increase in the SCE frequency was observed in those cultures treated without the S9 mix. In addition, cytotoxic/cytostatic effects of the G-1 compound were observed mainly in cultures without S9 fraction, as indicated by the reduction of cell proliferation measured by the cytokinesis block proliferation index (CBPI) and the proliferative rate index (PRI).

GSTM1, GSTT1, and GSTP1 genotypes and the genotoxicity of hydroquinone in human lymphocytes

Hydroquinone is a myelotoxin that is found in many foods and is also formed through the metabolism of benzene. Human exposure to benzene is associated with the development of myelodysplastic syndrome and acute myelogenous leukemia. Hydroquinone is genotoxic in several in vitro and in vivo test systems, inducing micronuclei (MN), sister-chromatid exchange (SCE), and chromosomal aberrations. Glutathione S-transferases (GSTs) are a superfamily of polymorphic enzymes involved in the conjugation of reactive chemical intermediates to soluble forms. These enzymes play a key role in the detoxification of endogenous and exogenous compounds, and the polymorphic genes GSTM1, GSTT1, and GSTP1 have been associated with the differential metabolism of several genotoxicants. In the present study, we have evaluated the effect of GSTM1, GSTT1, and GSTP1 polymorphisms on the frequency of MN and SCE induced by hydroquinone in human lymphocytes. Lymphocytes were obtained from 15 healthy non-smoking donors, and their GSTM1, GSTT1, and GSTP1 genotypes determined. Treatment of cultures of the lymphocytes with hydroquinone significantly increased the overall frequencies of MN and SCE (P<0.0001). Individuals with the GSTM1 null genotype had a significantly higher frequency of MN compared with GSTM1-present individuals (P=0.013); in contrast, the GSTM1 genotype had no effect on hydroquinone-induced SCE frequency. The other polymorphisms did not significantly affect the frequencies of MN or SCE. These results suggest that GSTM1 is involved in the metabolic fate of hydroquinone and that polymorphisms in GSTM1 could be related to inter-individual differences in DNA damage arising from the exposure to this compound.

Report from the in vitro micronucleus assay working group

At the Washington "2nd International Workshop on Genotoxicity Testing" (25-26 March 1999) current methodologies and data for the in vitro micronucleus test were reviewed. As a result, guidelines for the conduct of specific aspects of the protocol were developed. Agreement was achieved on the following topics: choice of cells, slide preparation, analysis of micronuclei, toxicity, use of cytochalasin-B, number of doses, and treatment/harvest times [Environ. Mol. Mutagen. 35 (2000) 167]. Because there were a number of important in vitro micronucleus validation studies in progress, it was not possible to design a definitive, internationally harmonized protocol at that time. These studies have now been completed and the data were reviewed at the Plymouth "3rd International Workshop on Genotoxicity Testing" (28-29 June 2002). Data from studies coordinated by the French Society of Genetic Toxicology, Japanese collaborative studies, European pharmaceutical industry validation studies, along with data from Lilly Research Laboratories were used to prepare conclusions on the main aspects of the in vitro micronucleus protocol. In this paper, the consensus agreements on the protocol for performing the in vitro micronucleus assay are presented. The major recommendations concern: 1. Demonstration of cell proliferation: both cell lines and lymphocytes can be used, but demonstration of cell proliferation in both control and treated cells is compulsory for the acceptance of the test. 2. Assessment of toxicity and dose range finding: assessment of toxicity should be performed by determining cell proliferation, e.g. increased cell counts (CC) or population doubling (PD) without cytochalasin-B, or e.g. cytokinesis-block proliferation index with cytochalasin-B; and by determining other markers for cytotoxicity (confluency, apoptosis, necrosis) which can provide valuable additional information. 3. Treatment schedules for cell lines and lymphocytes. 4. Choice of positive controls: without S9-mix both a clastogen (e.g. mitomycin C or bleomycin) and an aneugen (e.g. colchicine) should be included as positive controls and a clastogen that requires S9 for activity when S9-mix is used (e.g. dimethylnitrosamine, or cyclophosphamide in those cell types that cannot activate this agent directly). 5. Duplicate cultures and number of cells to be scored. 6. Repeat experiments: in lymphocytes, for each experiment blood from 2 different healthy young and non-smoking donors should be compared. In cell lines, the experiments need only to be repeated if the first one is negative. 7.

STATISTICS

statistical significance should not be the sole factor for determining positive results. Biological meaning should serve as a guideline. Examples of statistical analyses are given.

Lack of genotoxic effects (micronucleus induction) in human lymphocytes exposed in vitro to 900 MHz electromagnetic fields

In the present study, we investigated the induction of genotoxic effects in human peripheral blood lymphocytes after exposure to electromagnetic fields used in mobile communication systems (frequency 900 MHz). For this purpose, the incidence of micronuclei was evaluated by applying the cytokinesis-block micronucleus assay. Cytotoxicity was also investigated using the cytokinesis-block proliferation index. The experiments were performed on peripheral blood from 20 healthy donors, and several conditions were tested by varying the duration of exposure, the specific absorption rate (SAR), and the signal [continuous-wave (CW) or GSM (Global System of Mobile Communication) modulated signal]. The following exposures were carried out: (1) CW intermittent exposure (SAR = 1.6 W/kg) for 6 min followed by a 3-h pause (14 on/off cycles); (2) GSM signal, intermittent exposure as described in (1); (3) GSM signal, intermittent exposure as described in (1) 24 h before stimulation with phytohemagglutinin (8 on/off cycles); (4) GSM signal, intermittent exposure (SAR = 0.2 W/kg) 1 h per day for 3 days. The SARs were estimated numerically. No statistically significant differences were detected in any case in terms of either micronucleus frequency or cell cycle kinetics.

Sister chromatid exchanges and micronuclei analysis in lymphocytes of men exposed to simazine through drinking water

In some cities of the autonomous community of Extremadura (south-west of Spain), levels of simazine from 10 to 30 ppm were detected in tap water. To analyse the possible effect of this herbicide, two biomarkers, sister chromatid exchanges (SCE) and micronuclei (MN), were used in peripheral blood lymphocytes from males exposed to simazine through drinking water. SCE and MN analysis failed to detect any statistically significant increase in the people exposed to simazine when compared with the controls. With respect to high frequency cells (HFC), a statistically significant difference was detected between exposed and control groups.

Mutagenic and genotoxic evaluation of bisphenol F diglycidyl ether (BFDGE) in prokaryotic and eukaryotic systems

The epoxy resin bisphenol F diglycidyl ether (BFDGE), was examined for its mutagenicity in prokaryotic assays (Salmonella typhimurium His(-) and Escherichia coli Trp(-) tests) and its genotoxicity in eukaryotic systems (sister chromatid exchange (SCE) and micronucleus tests in human lymphocytes), in the presence or absence of an exogenous metabolizing system (S9 from rat liver). In the prokaryotic tests, the concentrations of BFDGE ranged between 100 and 5000 micro g per plate, and in the eukaryotic assays from 12.5 to 62.5 micro g/ml. The compound is able to induce mutagenic effects in bacterial strains TA100, TA1535, WP2uvrA and IC3327, as revealed by the increase observed in the number of induced revertants. With respect to the genotoxicity assays, BFDGE induces an increase in the frequency of sister chromatid exchanges and micronuclei in human peripheral blood lymphocytes.

Pyrethroids used indoors--immune status of humans exposed to pyrethroids following a pest control operation--a one year follow-up study

A multiparametric analysis of immune components was performed in blood and serum of 61 voluntary persons before and after (1 day, 3 days, 4-6 months, 10-12 months) a professional pest control operation (PCO) using pyrethroids. Following parameters were included in the study (1) immunological parameters of the humoral defence, i.e. immunoglobulins of the classes A, G, M and E, complement components C3c and C4, acute phase proteins such as acid alpha 1-glycoprotein, haptoglobin, C-reactive protein; (2) mediators and receptors of immunity, i.e. neopterin, soluble interleukin-2 receptor (sIL-2R), soluble interleukin-6 receptor (sIL-6R), soluble tumor necrosis factor receptor (sTNF RII); (3) immunological markers of the cellular defence, i.e. white blood cell counts and lymphocyte (sub)populations such as total lymphocytes (CD2), mature lymphocytes (CD3), T-helper/inducer cells (CD4), T-suppressor/cytotoxic cells (CD8), B-cells (CD20), natural killer cells (CD56), as well as the ratio of CD4/CD8. The medians of all investigated immune components found before and for all time intervals after pyrethroid application were within the reference interval with respect to the total collective. Within this physiological range the investigated parameters showed a trend to lower values predominantly during the early phase (1 and 3 days) after PCO, partially being significant. Significant decreases were no more present in the late phase (6 to 12 month) after PCO indicating reversibility. Atopics did not differ in the immune response after PCO as compared to non-atopics. Obtained results suggest a modulation of immune components after a correct performed PCO within the physiological range towards lower values during the first days. However these immune changes are considered to be subtle and underlying compensatory mechanisms of immunoregulation.

Evaluation of the genotoxic potential of lambda-cyhalothrin using nuclear and nucleolar biomarkers on fish cells

Micronucleus formation in fish erythrocytes, as an indicator of chromosomal damage, has been increasingly used to detect the genotoxic potential of environmental contaminants. Nucleolar organizer regions (NORs) stained with colloidal silver techniques indicate sites of active RNA transcription. The number and size of NORs in interphase nuclei reflect cellular activities such as proliferation and differentiation of cells. In this study, nuclear (micronucleus frequency) and nucelolar (changes in quantitative characteristics of nucleoli) biomarkers were used to evaluate the functional and structural genotoxic effects of the pyrethroid insecticide lambda-cyhalothrin on Garra rufa (Pisces: Cyprinidae). The frequency of micronuclei was examined in blood smears obtained from fishes exposed to three different concentrations (0.005, 0.01, 0.05 microg/l) for a period of 36 h. Nucleolar parameters (the average number of nucleoli per cell; the volume of a single nucleolus; and the percentage of cells with heteromorphic paired nucleoli) were examined in epithelial cells obtained from the edge of caudal fins at the 90th and 180th minutes of exposure. Results of both tests demonstrated the genotoxic potential of pyrethroid lambda-cyhalothrin on G. rufa. The frequency of micronucleated erythrocytes was significantly increased while the nucleolar parameters were repressed by lambda-cyhalothrin treatment. Our results confirmed that the use of nucleolar biomarkers on fish fin cells, in addition to micronucleus test, could provide valuable information in aquatic genotoxicity studies.

Possible transient adaptive response to mitomycin C in peripheral lymphocytes from thyroid cancer patients after iodine-131 therapy

Our study attempted to assess the possible induction and persistence of an adaptive response in lymphocytes of thyroidectomized thyroid cancer patients treated with 131I (2,590 MBq, corresponding to whole body doses in the range of 200-300 mGy), to a testing dose of mitomycin C (MMC) in vitro. The cytogenetic endpoint studied was the induction of micronuclei in cytokinesis-blocked peripheral blood lymphocytes, immediately before treatment and 1, 6 and 24 months after therapy. One month after therapy, induction of micronucleated cytokinesis-blocked lymphocytes ( per thousand ) by MMC was lower (34.6 +/- 7.7) than before therapy (52.1 +/- 5.0). In 7 of 11 patients this reduction was significant. However, at 6 months, induction of micronuclei was markedly higher (133.1 +/- 13.6). This significant increase was observed regardless of the decrease at 1 month. At 24 months, the frequency of micronucleated cells decreased (84.8 +/- 5.5), but remained higher than before treatment. The results obtained 1 month after therapy could reflect adaptation due to radiation, or a higher rate of early apoptosis or cell death, with bone marrow suppression, visible as a lower response in vitro towards MMC. At 6 months, recovery of the lymphocyte population may occur, and higher responses to MMC in vitro could reflect higher chromosomal instability in the previously irradiated stem cells with a concomitant disappearance of adaptation, whereas at 24 months the results show a tendency to return to pretherapy values.

Assessment of cytogenetic damage in lymphocytes and in exfoliated nasal cells of dental laboratory technicians exposed to chromium, cobalt, and nickel

Dental laboratory technicians may be exposed to metal alloys that are used in the production of crowns, bridges and removable partial dentures. These alloys consist of 35-65% cobalt, 20-30% chromium, 0-30% nickel, and small amounts of molybdenum, silica, beryllium, boron and carbon. The aim of this study was to assess whether dental technicians are occupationally exposed to chromium, cobalt and nickel, by analyzing urinary excretion levels of these metals and to investigate the genotoxic effects of occupational exposure associated with dental prostheses production operations by analyzing cytokinesis-blocked micronucleus (CB-MN) frequencies in peripheral lymphocytes and micronucleus (MN) frequencies in exfoliated nasal cells from 27 dental laboratory technicians and 15 control subjects. The differences in the urinary excretion of metals between technicians and controls were statistically significant. The mean (+/-S.D.) CB-MN frequencies ( per thousand ) in peripheral lymphocytes were 4.00 (+/-2.98) among the dental technicians and 1.40 (+/-1.30) among the controls, a statistically significant difference (P<0.005). The mean (+/-S.D.) MN frequencies ( per thousand ) in nasal cells were 3.50 (+/-1.80) among the dental technicians and 1.19 (+/-0.53) among the controls, which was also a statistically significant difference (P<0.005). There was a significant correlation between duration of exposure and MN frequencies in lymphocytes (r=0.642, P<0.01), but not in nasal cells of technicians. Our data reveal that in vivo exposure to chromium, nickel and cobalt metals is evident and that this occupational exposure may contribute to the observed genotoxic damage in two types of cells, e.g. lymphocytes and exfoliated nasal cells. However, it cannot be determined which compound(s) are responsible for the genotoxic damage observed in this study.

Fenvalerate-induced chromosome aberrations and sister chromatid exchanges in the bone marrow cells of mice in vivo

Fenvalerate, a synthetic pyrethroid insecticide, is commonly used in agriculture and other domestic applications due to its high insecticidal activity and low mammalian-, avian- and phyto-toxicities. However, the genotoxic effect of fenvalerate is highly equivocal. In the present study the genotoxic effects of fenvalerate was evaluated using structural chromosome aberration (CA) and sister chromatid exchange (SCE) assays in mice. Out of the three doses (5, 10 and 20 mg/kg) tested, statistically significant increase in CA was found following intra peritoneal (i.p.) treatment of 2 0 mg/kg of fenvalerate for 24 h (P<0.01) and 48 h (P<0.05) only. Neither the acute doses of 5 and 10 mg/kg, nor the sub-acute dose (5x4 mg/kg) of fenvalerate could induce any significant effect. All the three acute doses induced significant increase in the frequency of SCEs (P<0.01) in the bone marrow cells, which showed a significant dose-response correlation (r=0.9541, P<0.05). With certain reservations to possible impurities, from the present findings technical grade fenvalerate may be considered as a weak clastogen and a potent inducer of SCEs in mice.

Genotoxic evaluation of the furylethylene derivative 1-(5-bromofur-2-yl)-2-nitroethene in cultured human lymphocytes

The genotoxicity of the 2-furylethylene derivative 1-(5-bromofur-2-yl)-2-nitroethene (2-betaNF) has been evaluated in cultured human peripheral blood lymphocytes at concentrations ranging from 0.5 to 15microg/ml. The frequencies of micronuclei (MN) and sister-chromatid exchanges (SCEs) were used and scored as indicators of genetic damage. To asses the role of the metabolism mediated by the enzymes present in the S9 mix, over the possible genotoxic potential of the test agent, the cultures for MN and SCE demonstrations were treated for 3h in presence and in absence of rat liver microsomal fraction. The results indicate that, under the experimental conditions used, the test agent does not induce significant increases in the frequency of micronucleated cells, irrespective of the presence/absence of metabolic fraction. Nevertheless, a slight increase in the SCE frequency was observed in those cultures treated without the S9 mix; although this slight increase disappeared in the experiments carried out with the microsomal fraction. In addition, cytotoxic/cytostatic effects of (2-betaNF) were observed mainly in the cultures treated without the S9 fraction.

Carcinogenic and cocarcinogenic potential of cypermethrin on mouse skin

Cypermethrin (CYM), a synthetic pyrethroid insecticide, is used widely because of its high bio-efficacy and low mammalian toxicity. In the present set of investigations, CYM has been evaluated for it's carcinogenic and co-carcinogenic (tumour initiating and tumour promoting) potential in mouse skin model of carcinogenesis. The results revealed that CYM possess complete carcinogenic as well as tumour initiating and promoting potential in both the sexes of Swiss albino mice. At the end point, i.e. 32 weeks in a single dose (10 mg/kg body weight (wt.), once only), initiated mice, 9 out of 12 surviving males, and 10 out of 14 surviving females developed benign tumours, while a higher incidence of tumourigenesis was recorded in multiple dose-initiated (10 mg/kg body wt., total nine applications) group, where 7 out of 9 surviving male and 10 out of 13 surviving female mice developed tumours at the site of topical exposure. The application of CYM as a tumour promoter on 7,12-dimethylbenz(a)anthracene initiated animals induced tumour incidence in about 4 out of surviving 10 male and 5 out of surviving 13 female Swiss albino mice. CYM when tested for complete carcinogenic activity induced tumour formation in both male and female animals at all the three tested dose levels.

Micronuclei and sister chromatid exchanges induced by capsaicin in human lymphocytes

Capsaicin is the main pungent and irritating component of hot peppers (species Capsicum annuum and C. frutescens). Genotoxicity and carcinogenicity studies evaluating capsaicin effects are sparse and contradictory. In this study, we investigated the genotoxicity of capsaicin (10-200 microM) in human peripheral blood lymphocytes using the cytokinesis-block micronucleus (CBMN) assay and the sister chromatid exchange (SCE) assay in the presence or absence of external metabolic activation. Capsaicin induced the formation of micronuclei (MN) in a dose-dependent manner in the cytokinesis-blocked lymphocytes. This increase was more evident in the absence of metabolic activation, with a maximum of 3.4-fold increase above the background. Some inter-individual variability was observed. The results for the SCE assay also show that capsaicin is genotoxic and in this case with a more homogeneous response among donors. This end-point, however, has proven to be less sensitive than the CBMN assay for capsaicin.

Evaluation of genotoxic effects in a group of workers exposed to low levels of styrene

Occupational exposure to styrene was studied in a group of workers engaged in the production of fiberglass-reinforced plastics. Sister-chromatid exchanges (SCE), micronuclei (MN), and DNA damage (evaluated by means of comet assay) were measured in peripheral blood cells from the exposed workers and from a control population. Mandelic acid concentration, an indicator of styrene exposure level, was measured in urine samples collected at the end of the work shift. Average estimated values for styrene exposure were slightly below the threshold limit value (TLV) of 20 ppm recommended by the American Conference of Governmental Industrial Hygienists. Significant increases (P< or =0.01) have been found for SCE and MN frequencies and comet tail length among exposed individuals, as well as significant decreases (P< or =0.01) in the proliferation indices, as compared with control population. High correlation has been obtained between endpoints evaluated and exposure length, and increased values of SCE and MN frequencies and comet tail length have been found among smokers only in the exposed population. The high correlation obtained among SCE and MN frequencies and comet tail length, and the increase of these parameters in the exposed group with regard to control group justify the use of these three biomarkers in the evaluation of genotoxic effects in human populations exposed to styrene.

Occupational exposure to pesticides and cytogenetic damage: results of a Hungarian population study using the micronucleus assay in lymphocytes and buccal cells

The frequency of micronuclei (MN) in peripheral blood lymphocytes and in buccal epithelial cells was used as a biomarker of genotoxic effects resulting from occupational exposure to pesticides. In addition, the cytokinesis-block proliferation index (CBPI) was calculated to detect possible variations in the proliferative kinetics of lymphocytes due to pesticide exposure. This study was performed on 84 pesticide-exposed workers and 65 unexposed controls from Hungary. The pesticide-exposed workers, classified as moderately and highly exposed, were also evaluated separately. Statistical evaluation of the cytogenetic biomarkers indicated that there were no significant differences between pesticide-exposed workers and controls, nor between moderately and highly exposed workers. Nevertheless, the statistical analysis revealed that additional factors such as age, sex, ingestion of raw vegetables, and working as a pesticide applicator affected lymphocyte MN frequency. In addition, age, sex, and smoking affected the frequency of MN in buccal cells. Results from the CBPI analysis showed that the proliferation index decreased with pesticide exposure and that this parameter was also affected by smoking and by the gender of individuals. The results of this study indicate no significant increase in MN in this group of Hungarian workers; however, the reduced CBPI in the highly exposed population suggests a possible genotoxic effect of pesticide exposure.

Cytogenetic damage in human lymphocytes following GMSK phase modulated microwave exposure

The present study investigated, using in vitro experiments on human lymphocytes, whether exposure to a microwave frequency used for mobile communication, either unmodulated or in presence of phase only modulation, can cause modification of cell proliferation kinetics and/or genotoxic effects, by evaluating the cytokinesis block proliferation index and the micronucleus frequency. In the GSM 1800 mobile communication systems the field is both phase (Gaussian minimum shift keying, GMSK) and amplitude (time domain multiple access, TDMA) modulated. The present study investigated only the effects of phase modulation, and no amplitude modulation was applied. Human peripheral blood cultures were exposed to 1.748 GHz, either continuous wave (CW) or phase only modulated wave (GMSK), for 15 min. The maximum specific absorption rate (approximately 5 W/kg) was higher than that occurring in the head of mobile phone users; however, no changes were found in cell proliferation kinetics after exposure to either CW or GMSK fields. As far as genotoxicity is concerned, the micronucleus frequency result was not affected by CW exposure; however, a statistically significant micronucleus effect was found following exposure to phase modulated field. These results would suggest a genotoxic power of the phase modulation per se.

Genotoxic evaluation of the furylethylene derivative 2-furyl-1-nitroethene in cultured human lymphocytes

The compound 2-furyl-1-nitroethene (G-0) was evaluated for genotoxicity in cultured human peripheral blood lymphocytes, at concentrations ranging from 1 to 15microg/ml. Micronuclei (MN) and sister-chromatid exchanges (SCEs) were scored as genetic endpoints. In order to detect the role of metabolic enzymes on the genotoxicity of this furylethylenic derivative, the cultures for MN and SCE demonstrations were also treated with S9 microsomal fraction. The results indicate that, under the conditions of the study, the test agent does not seem to induce significant increases in the frequency of micronucleated cells, irrespective of the presence of metabolic activation. Nevertheless, a slight increase in the SCE frequency was observed in those cultures treated without the S9 mix; although this increase disappeared in presence of the microsomal fraction. In addition, cytostatic effects of 2-furyl-1-nitroethene were observed mainly in cultures without S9 fraction, as indicated by the reduction of cell proliferation.

Micronuclei in peripheral blood lymphocytes and buccal epithelial cells of Polish farmers exposed to pesticides

In this biomonitoring study, we investigated whether an occupational exposure to a complex mixture of chemical pesticides produced a significant increase of micronuclei (MN) in both peripheral blood lymphocytes and buccal cells. Forty-nine male workers exposed to pesticides, from an agricultural area of Malopolska Region in Southern Poland, together with 50 men from the same area without indication of exposure to pesticides that served as controls, were used in this investigation. No statistically significant differences in the frequencies of cytogenetic damage were detected between exposed and control individuals, for either type of cells. The multiple linear regression analysis in the case of lymphocytes indicated that the studied cytogenetic endpoints were inversely influenced by alcohol; whilst a negative binomial regression, in the case of buccal cells, indicated that the MN values were directly influenced by the ingestion of red meat. An inverse negative relationship between the cytokinesis-block proliferation index and age, and a significant increase of miscarriages due to the exposure to pesticides were also observed.

The protection of Vitamin E and selenium against carbon tetrachloride-induced genotoxicity in ovine peripheral blood lymphocytes

The protective effect of Vitamin E and selenium was studied for the possibility of decreasing the chromosome aberrations (CA), micronuclei (MN) and sister chromatid exchanges (SCE) induced by carbon tetrachloride (CCl(4)) in ovine peripheral lymphocytes cultured in vitro. The cultures of lymphocytes from two healthy lambs were treated with carbon tetrachloride at concentrations of 2, 4, 8, and 16 microg/ml for the last 48 h of cultivation and subsequently with the same doses of CCl(4) and Vitamin E and selenium. A possible metabolic modification in carbon tetrachloride genotoxicity was detected with the application of S9 fraction for 2h. No positive clastogenic effect of CCl(4), and subsequently no protective effect of either antioxidant was obtained in the CA assay. In the MN assay for 48 h, an increase and, respectively, a decrease in the frequency of MN was found in cultures treated with CCl(4) alone and in cultures treated concurrently with CCl(4), Vitamin E and selenium at concentrations of 8 and 16 microg/ml (P<0.001 and P<0.01). High statistical significance was achieved in SCE assay after the treatment of ovine peripheral lymphocytes with CCl(4) at all concentrations tested (P<0.001), except the lowest dose. A significant decrease in SCEs was obtained in cultures treated simultaneously with CCl(4), Vitamin E and selenium (P<0.001). The highest dose (16 microg/ml) was also shown to improve the cell-cycle kinetics in comparison with corresponding unprotected dose (P<0.01). Insufficient confirmation of the genotoxicity of CCl(4) and the protective effect of the antioxidants, respectively were seen in cultures with metabolic activation.

Genotoxic effects of styrene-7,8-oxide in human white blood cells: comet assay in relation to the induction of sister-chromatid exchanges and micronuclei

Styrene is used in the production of plastics, resins and rubber. The highest human exposures to styrene take place by inhalation during the production of fiberglass reinforced plastics. Styrene is metabolized mainly in the liver to styrene-7,8-oxide (SO), its principal in vivo mutagenic metabolite. In this study, human peripheral white blood cells were exposed to several SO concentrations (10-200 microM) in order to evaluate its genotoxic properties by means of comet assay, sister-chromatid exchanges (SCE) and cytokinesis-blocked micronucleus (MN) test, in addition to determine its clastogenic or aneugenic properties by combining MN with fluorescence in situ hybridization (FISH) procedures. Our results show that SO induces DNA damage, SCE and MN in human leukocytes in vitro at concentrations above 50 microM, and that there is a strong relationship between DNA damage, as measured by the comet assay, and cytogenetic damage induced by SO at the doses employed. SO shows preferentially a clastogenic activity and produces a cytostatic effect at high doses, reflected by the significant decrease of the calculated proliferation indices. A good dose-effect relationship is obtained in the three tests performed at the concentration range assayed.

No evidence of increased chromosomal aberrations and micronuclei in lymphocytes from nonfamilial thyroid cancer patients prior to radiotherapy

The relationship between the presence of high frequencies of chromosomal aberrations in peripheral lymphocytes and predisposition to cancer has been suggested for some cancer diseases. In nonfamilial thyroid cancer, the few reports available are equivocal. The aim of this study was to assess the possible chromosomal instability in peripheral blood lymphocytes from 22 patients suffering from nonfamilial thyroid cancer. For this purpose, 2 classic cytogenetic assays, the chromosomal aberrations assay and cytokinesis-blocked micronucleus assay, were chosen. The frequency of chromosomal aberrations excluding gaps (%) was 1.68 +/- 1.39 (mean value +/- SD) for the patients group versus 2.20 +/- 1.87 for the control group. The frequency of binucleated lymphocytes with micronuclei ( per thousand) was 5.41 +/- 3.51 (mean value +/- SD) for the patients group versus 5.37 +/- 3.21 for the control group. The results obtained revealed no significant differences between both groups. The present study reinforces the idea that constitutional chromosomal instability in peripheral blood lymphocytes is not visible in nonfamilial thyroid carcinomas.

Genotoxicity of the coating lacquer on food cans, bisphenol A diglycidyl ether (BADGE), its hydrolysis products and a chlorohydrin of BADGE

The epoxy resin bisphenol A diglycidyl ether (BADGE), its hydrolysis products and a chlorohydrin of BADGE (BADGE.2HCl), were examined for their genotoxicity in the micronucleus test (MNT) with human peripheral blood lymphocytes in vitro, in presence and in absence of an exogenous metabolizing system S9 rat liver. The treatment was done using different compound concentrations up to cytotoxic doses. The concentrations tested ranged between 12.5 to 62.5microg/ml of BADGE, 12.5 to 62.5microg/ml of first BADGE hydrolysis product (BADGE.H(2)O), 25.0 to 100.0microg/ml of second BADGE hydrolysis product (BADGE.2H(2)O) and 6.25 to 50.0microg/ml of BADGE.2HCl. These compounds are able to induce both cytotoxic and genotoxic effects, as revealed by the increases observed in cytokinesis block proliferation index (CBPI) and in micronuclei (MN) frequencies, respectively.

Mutagenic evaluation of deltamethrin using rodent dominant lethal assay

The dominant lethal test was used to analyse the mutagenic potential of deltamethrin, a synthetic pyrethroid insecticide, in Swiss albino mice. In the treated series, the animals were exposed orally to three different doses (0.36, 0.72 and 1.08 mg/kg body weight) of deltamethrin dissolved in corn oil. Following the treatment, each male of control, as well as of the treated series, was mated with untreated females, every week for a period of 6 weeks. All mated females were sacrificed on the 13th day of separation and their ovaries and uterus were examined. The results revealed that deltamethrin treatment did not impair the mating capacity and fertility of Swiss albino mice. Mutagenic index, pre- and post-implantation losses were assessed. No significant pre-implantation losses were observed either weekly or averagely. Post-implantation losses were observed at medium and high doses of deltamethrin. A slight increase in dominant lethal mutation rate was observed by increasing doses of deltamethrin in early weeks but decreased in later weeks, so an apparent dose response was not observed.

Cytogenetic biomonitoring of Spanish greenhouse workers exposed to pesticides: micronuclei analysis in peripheral blood lymphocytes and buccal epithelial cells

In the present study, we evaluate whether or not occupational exposure to a complex mixture of pesticides results in a significant increase of micronuclei (MN) in both peripheral blood lymphocytes and buccal cells. Sixty four greenhouse workers from Almería (Southeastern Spain), together with 50 men from the same area, without indication of exposure to pesticides, that served as controls were used in this investigation. The results obtained indicate that there are no statistically significant differences in the MN frequencies between the two groups. Each donor was assessed for the presence or absence of glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1), to look for relationships between the genotypes and the cytogenetic reponses. According to the GSTT1 genotype, there is a difference between both groups only for the cytokinesis-block proliferation index (CBPI). Neither GSTM1 nor smoking habit and age showed any effect in the overall analysis.

Biomarkers of DNA damage in marine mammals

Certain environmental contaminants found in marine mammals have been shown to cause DNA damage and cancer. The micronuclei (MN), sister chromatid exchange (SCE) and/or chromosome aberration (CA) assays were used to assess baseline (spontaneous) levels of DNA damage in blood lymphocytes of individuals of the relatively healthy and lightly contaminated Arctic beluga whale (Delphinapterus leucas), Sarasota Bay, FL, bottlenose dolphin (Tursiops truncatus) and Northwestern Atlantic grey (Halichoerus grypus) and harp (Phoca groenlandicus) seal populations. MN cell (MNC) frequencies ranged between 2 and 14/1000 binucleated (BN) cells and were statistically similar between species. In bottlenose dolphins, MNC frequency was correlated with age and was significantly higher in females than in males. No intraspecific variation in MNC frequency was found in beluga whales. Intraspecific variation was not tested in seals due to the small sample size. Frequencies of SCEs and total CAs, excluding gaps, ranged, respectively, between 1 and 15 SCE(s)/per cell and 4-6 CAs/100 cells in beluga whales. SCE and CA frequencies did not vary with age or sex in beluga whales. The MN, SCE and CA assays were found to be practical tools for the detection of DNA damage in marine mammals and could be used in the future to compare DNA damage between relatively lightly and highly contaminated populations.

Excision repair of nitrogen mustard-DNA adducts in Saccharomyces cerevisiae

The bifunctional alkylating anticancer drug nitrogen mustard forms a variety of DNA lesions, including monoadducts and intrastrand and interstrand crosslinks. Although it is known that nucleotide excision repair (NER) is important in processing these adducts, the role of the other principal excision repair pathway, base excision repair (BER) is less well defined. Using isogenic Saccharomyces cerevisiae strains disrupted for a variety of NER and BER genes we have examined the relative importance of the two pathways in the repair of nitrogen mustard adducts. As expected, NER defective cells (rad4 and rad14 strains) are extremely sensitive to the drug. One of the BER mutants, a 3-methyladenine glycosylase defective (mag1) strain also shows significant hypersensitivity. Using a rad4/mag1 double mutant it is shown that the two excision repair pathways are epistatic to each other for nitrogen mustard sensitivity. Furthermore, both rad14 and mag1 disruptants show elevated levels of nitrogen mustard-induced forward mutation. Measurements of repair rates of nitrogen mustard N-alkylpurine adducts in the highly transcribed RPB2 gene demonstrate defects in the processing of mono-adducts in rad4, rad14 and mag1 strains. However, there are differences in the kinetics of adduct removal in the NER mutants compared to the mag1 strain. In the mag1 strain significant repair occurs within 1 h with evidence of enhanced repair on the transcribed strand. Adducts however accumulate at later times in this strain. In contrast, in the NER mutants repair is only evident at times greater than 1 h. In a mag1/rad4 double mutant damage accumulates with no evidence of repair. Comparison of the rates of repair in this gene with those in a different genomic region indicate that the contributions of NER and BER to the repair of nitrogen mustard adducts may not be the same genome wide.

Induction of mitotic cell division distrubances and mitotic arrest by pyrethroids in V79 cell cultures

Five pyrethroids (fenvalerate, deltamethrin, cypermethrin, permethrin, cyfluthrin) differing in their chemical purity were investigated on their cytotoxic effects, especially on their ability to induce mitotic cell division disturbances using Chinese hamster lung cells of line V79. The colony forming ability (CFA) resulted in distinct differences of the cytotoxic effect of the tested pyrethroids, whereby permethrin was found to be most toxic. With the exception of fenvalerate all tested pyrethroids gave rise to inhibition of cell cycle progression as shown by G2/M-arrest of synchronized V79 cells by flow cytometry as well as by the increase of the mitotic index as evaluated by light microscopy. The mitotic arresting activity could be attributed to the occurrence of abnormal mitotic figures such as initial and full C-metaphases. The results however indicate, that pyrethroids per se do not contribute to the cytotoxic effects but that other factors such as chemical impurities, source as well as manufacturing process and isomer composition may be responsible for the observed cytotoxic effects.

Pyrethroids and piperonyl-butoxide affect human T-lymphocytes in vitro

Synthetic pyrethroids are increasingly used as insecticides and are claimed to have a relatively low human toxicity. The aim of this study was to examine the in vitro effects of the synthetic pyrethroid S-bioallethrin alone and in combination with the common synergist piperonyl-butoxide (PBO) on human blood lymphocytes and basophils in atopic individuals and non-atopic control subjects. S-bioallethrin and PBO also caused inhibition of lymphocyte proliferation (MTT-test) after a 72-h culture period in a concentration dependent manner. In contrast to the MTT-measurements the combined agents are more effective in inhibiting interleukin-4 (IL-4)- and interferon-gamma (IFN-gamma)-production. The regulatory IL-4/IFN-gamma balance showed a significant difference between atopic and non-atopic subjects after a culture period of 24-48 h in the presence of micromolar S-bioallethrin (P < 0.001). Furthermore S-bioallethrin, PBO and the combined agents induced histamine release from human basophils. Although this effect was little compared to histamine liberators like FMLP and anti-IgE, the response to S-bioallethrin and PBO was significantly different in atopic donors compared with non-atopics (P < 0.01). In scratch test experiments 4 of 18 tested atopic volunteers showed positive reaction (wheals and flares) to S-bioallethrin and permethrin, whereas no reaction could be measured in the control group (age-matched). These findings demonstrate the immuno- and allergo-toxicological properties of the synthetic pyrethroid S-bioallethrin combined with the synergistic PBO using this in vitro approach with human lymphocytes and basophils.

Genotoxic evaluation of the antimicrobial drug, trimethoprim, in cultured human lymphocytes

The antimicrobial drug, trimethoprim, was evaluated for genotoxicity in human peripheral blood lymphocyte cultures set-up from two healthy donors. Sister-chromatid exchanges (SCE) and micronuclei (MN) were scored as genetic endpoints. The treatment was done using different trimethoprim concentrations ranging from 1 to 100 microg/ml. From our results, we can conclude that this drug is able to induce both cytotoxic and moderate genotoxic effects, as revealed by the increases seen in SCE and MN frequencies in cultures from the two donors and, at least, at one of the concentrations tested.

Examination of various biomarkers measuring genotoxic endpoints from Barcelona airport personnel

Three different biomarkers: sister-chromatid exchanges (SCE), micronuclei (MN), and the Comet assay, were used to evaluate different kinds of genetic damage in peripheral blood lymphocytes from 34 male workers at Barcelona airport, exposed to low levels of hydrocarbons and jet fuel derivatives. The control group consisted of 11 unexposed men. We also investigated the ras p21 protein levels in plasma, in order to evaluate whether the ras gene could serve as a suitable potential marker of carcinogenic pollution in occupationally exposed cohorts. SCE and MN analyses failed to detect any statistically significant increase in the airport workers when compared with the controls, and in fact, the frequency of binucleated cells with MN in the exposed group was significantly lower than that obtained in the control. However, slight but significant differences in the mean comet length and genetic damage index were observed between the exposed and control groups when using the Comet assay. There were no statistically significant differences between both groups in p21 plasma levels. Smoking was shown to affect significantly both SCE and high frequency cells (HFC) in the exposed group.

Induction of micronuclei in vitro by organochlorine compounds in beluga whale skin fibroblasts

Beluga whales (Delphinapterus leucas) inhabiting the St. Lawrence estuary are highly contaminated with environmental pollutants and have a high incidence of cancer. Environmental contaminants may be partly responsible for the high cancer incidence observed in this population. DNA damage plays an important role in the development of cancer. The micronuclei (MN) assay was used to test the genotoxic potential of organochlorine (OC) pesticides with and without external metabolic factor in skin fibroblasts of an Arctic beluga whale. Toxaphene, chlordane and p,p'-DDT induced significant (p<0. 05) concentration-response increases of micronucleated cells (MNCs). Statistically significant increases in MNCs, ranging from 1.7- to 5-folds when compared to control cultures, were observed for 0.05, 0. 5, 5 and 10 microg/ml toxaphene, 2, 5 and 10 microg/ml chlordane and 10 and 15 microg/ml p,p'-DDT. Presence of exogeneous metabolic factor (S9) completely abolished the MN induction potency of chlordane and p,p'-DDT, and toxaphene induced MN formation at higher concentrations (0.5 microg/ml) than without S9 mix. The ecotoxicological significance of MN induction by low concentrations of toxaphene is unknown and do not imply that toxaphene is involved in the etiology of cancer in St. Lawrence beluga whales. However, because of the known genotoxicity of toxaphene and the long lifespan of beluga whales, it cannot be excluded that toxaphene may pose a long-term genetic hazard to the more contaminated whales of this population.

Genotoxic evaluation of the pyrethroid lambda-cyhalothrin using the micronucleus test in erythrocytes of the fish Cheirodon interruptus interruptus

In order to develop experimental models able to detect genotoxic effects of pollutants in aquatic organisms, the genotoxicity of the pyrethroid lambda-cyhalothrin was studied using the micronucleus test in erythrocytes of Cheirodon interruptus interruptus. The frequency of micronuclei was examined in blood smears obtained from fishes exposed in vivo to three different concentrations (0.05; 0. 01; 0.001 ug/l) of the compound and sacrificed at nine sampling times (24, 48, 72, 96 h and 8, 12, 15, 19 and 23 days). As a positive control fishes were exposed to 5 mg/l of cyclophosphamide. Results obtained demonstrated the genotoxic effects of the pyrethroid in the experimental model employed. The variation in the micronuclei frequencies in the different sampling times could be related to the blood cell kinetics and the erythrocyte replacement. The results could be considered as a validation of the MN test in fishes for the assessment of genotoxic pollutants.

In vitro effects of the pyrethroid S-bioallethrin on lymphocytes and basophils from atopic and nonatopic subjects

Synthetic pyrethroids are increasingly used as insecticides and marketed as having relatively low human toxicity. The aim of this study was to examine the in vitro effects of the synthetic pyrethroid S-bioallethrin on human blood lymphocytes and basophils in atopic individuals and nonatopic control subjects. S-bioallethrin caused inhibition of lymphocyte proliferation after a 72-h culture period in a concentration-dependent manner. The inhibition of the lymphocyte proliferation by S-bioallethrin at the concentration 6.5 microM correlated well with the total serum IgE values (r = -0.89, P < 0.001). Samples from atopic subjects were more sensitive to this inhibition than those from nonatopic volunteers. The regulatory interleukin-4/interferon-gamma (JL-4/IFN-gamma) balance showed a significant difference between atopic and nonatopic subjects after a short-term culture period (24 h) in the presence of the same concentration range of S-bioallethrin (P < 0.001). Additionally, IFN-gamma secretion was consistently lower in cells from the atopic donors. Furthermore, S-bioallethrin induced histamine release from human basophils in a concentration-dependent manner. Although the effect was small compared to histamine liberators such as N-formyl-Met-Leu-Phe and anti-IgE, the response to S-bioallethrin was significantly different in atopic donors from nonatopic (P = 0.0431). These findings are the first demonstration of the immunotoxicologic properties of the synthetic pyrethroid S-bioallethrin by this combined in vitro approach with human lymphocytes and basophils. Further studies will investigate the responses of lymphocytes from patients who are sensitive to these agents.

Lack of genotoxicity of the herbicide atrazine in cultured human lymphocytes

The widely used herbicide atrazine was evaluated for genotoxicity in cultured human peripheral blood lymphocytes. Sister-chromatid exchanges (SCE), chromosome aberrations (CA) and micronuclei (MN) were scored as genetic endpoints. To detect eventual metabolic modification in the genotoxicity of this herbicide, the cultures of SCE and MN demonstration were also treated with S9 microsomal fraction. From our results we can conclude that atrazine was able to exert a weak cytotoxic effect. However, the overall evaluation of the genotoxicity data indicate that this herbicide is not effective in the three assays conducted, irrespective of the presence of metabolic activation, which would mean a general lack of effectiveness of atrazine to induce clastogenic and aneugenic damage in cultured human lymphocytes.

Clinical, cytogenetic and toxicological studies in rural workers exposed to pesticides in Botucatu, São Paulo, Brazil

Pesticides can cause gene mutations and chromosomal aberrations in exposed individuals. We have investigated 24 workers exposed to pesticides. Clinical examinations and cytogenetic and toxicological tests were performed. Ten non-exposed individuals were used as controls. Toxicological dosages of copper, zinc and manganese (metals found in some pesticides), hepatic enzyme dosage (GOT, GPT, AR) and acetylcholinesterase activity were performed in 16 workers and 8 controls. In the exposed workers, the most relevant clinical symptoms were poor digestion with fullness sensation after meals, irritated eyes, headache and fasciculations. The exposed group showed significantly lower manganese dosage and acetylcholinesterase activity, and significantly higher levels of alkaline phosphatase. Cytogenetic studies showed significantly higher chromosomal aberrations in the exposed group compared to the control group. Although the workers used protection against the pesticide's fog, the results revealed that the workers were contaminated with the pesticides. Therefore, the cytogenetic, toxicological studies with clinical examination are necessary for monitoring workers who are exposed to pesticides in any situation.