The comet assay with multiple mouse organs: comparison of comet assay results and carcinogenicity with 208 chemicals selected from the IARC monographs and U.S. NTP Carcinogenicity Database

Genotoxic and cytotoxic effects of polystyrene nanoplastics on human lymphocytes: A comprehensive analysis

A growing amount of plastic waste is finding its way into natural ecosystems as a result of the widespread usage of plastics in modern society. These wastes degrade physically and biologically over time, transforming into microplastics (MPs) and nanoplastics (NPs). MPs and NPs emissions from the terrestrial environment then mix with rivers and eventually the seas, forming garbage. The cytotoxic and genotoxic effects of 50 nm polystyrene nanoplastics (PsNP) on human lymphocytes were assessed using the in vitro mitotic index (MI), micronucleus (MN), and comet assays. Both 24 and 48-h applications were performed for MI, and it was determined that 50 nm PsNP provided a statistically significant decrease in MI compared to the control at all concentrations and application times (except 0.001 and 0.1 μg/mL at 24 h). According to the MN test results, the MN frequency increased significantly at all concentrations when compared to the negative control. In the comet test, a statistically significant increase of comet tail length was observed at 0.001, 10 and 100 μg/mL concentration with 50 nm PsNP exposure. Tail moment also showed a statistically significant increase at the lowest concentration of 0.001 μg/mL and the highest concentration of 1, 10, 100 μg/mL compared to the negative control. All test results show that PsNP has both genotoxic and cytotoxic potential.

Chemical and genotoxic characterization of bioaccessible fractions as a comprehensive in vitro tool in assessing the health risk due to dust-bound contaminant ingestion

In the last two decades, awareness grew on the matter of the impact of environment on human health. Contaminants sorbed onto soil and settled dust can be ingested and thus represent a hazard, particularly to young children, who play on the ground and bring their hands and objects to their mouth. Metal(loid)s and polycyclic aromatic hydrocarbons (PAHs) are of concern as they are both carcinogenic to humans and ubiquitous in outdoor environments. The present study aims to assess the total and bioaccessible fractions of PAHs and metal(loid)s present in settled dust of four preschools located in industrial, urban, and suburban areas. On the one hand, children's incremental life cancer risks (ILCR) were calculated according to ingestion pathway. On the other hand, the genotoxicities of the bioaccessible dust-bonded contaminants were determined on gastric cells. PAH concentrations ranged from 50.9 to 2267.3 ng/g, and the bioaccessible fraction represented 10.7% of the total in average. Metal(loid) concentration ranged from 12,430 to 38,941 µg/g, and the mean bioaccessibility was of 40.1%. Cancer risk ranged from 2.8.105 to 8.6.105, indicating that there is a potential cancer risk for children linked to the ingestion of settled dust. The inorganic bioaccessible fraction induced little DNA (< 20%TailDNA) and chromosomal damages (30% increase in micronuclei), whereas the organic bioaccessible fraction induced higher DNA (17-63%TailDNA) and chromosomal damages (88% increase in micronuclei). Such experimental approach needs to be deepen, as a tool complementary to cancer risk calculation, since the latter only lays on a set of targeted contaminants with known toxicity values.

Harnessing Efficient ROS Generation in Carbon Dots Derived from Methyl Red for Antimicrobial Photodynamic Therapy

The emergence of drug-resistant pathogenic microorganisms has become a public health concern, with demand for strategies to suppress their proliferation in healthcare facilities. The present study investigates the physicochemical and antimicrobial properties of carbon dots (CD-MR) derived from the methyl red azo dye. The morphological and structural analyses reveal that such carbon dots present a significant fraction of graphitic nitrogen in their structures, providing a wide emission range. Based on their low cytotoxicity against mammalian cells and tunable photoluminescence, these carbon dots are applied to bioimaging in vitro living cells. The possibility of using CD-MR to generate reactive oxygen species (ROS) is also analyzed, and a high singlet oxygen quantum efficiency is verified. Moreover, the antimicrobial activity of CD-MR is analyzed against pathogenic microorganisms Staphylococcus aureus, Candida albicans, and Cryptococcus neoformans. Kirby-Bauer susceptibility tests show that carbon dots synthesized from methyl red possess antimicrobial activity upon photoexcitation at 532 nm. The growth inhibition of C. neoformans from CD-MR photosensitization is investigated. Our results show that N-doped carbon dots synthesized from methyl red efficiently generate ROS and possess a strong antimicrobial activity against healthcare-relevant pathogens.

Evaluation of the cytotoxicity and genotoxicity potential of synthetic diacetyl food flavoring in silico, in vivo, and in vitro

Diacetyl is a common ingredient that creates a buttery flavor in baked goods and other food products. The cytotoxic impact of diacetyl on a normal human liver cell line (THLE2) indicated an IC50 value of 41.29 mg/ml through MTT assay and a cell cycle arrest in the G0/G1 phase relative to the control. Administration of diacetyl at two-time points (acute-chronic) led to a significant increase in DNA damage indicated by the increase in tail length, tail DNA%, and tail moment. The mRNA and protein expression levels of genes in the rats' livers were then measured using real-time PCR and western blotting. The results showed an activation of the apoptotic and necrosis mechanism, with an upregulation of p53, Caspase 3, and RIP1 and a downregulation of Bcl-2 at the mRNA level. The ingestion of diacetyl disrupted the liver's oxidant/antioxidant balance, as evidenced by alterations in levels of GSH, SOD, CAT, GPx, GR, MDA, NO, and peroxynitrite. Additionally, heightened levels of inflammatory cytokines were shown. Histopathological examinations revealed necrotic foci and congested portal areas in the rats' liver cells after treatment with diacetyl. Diacetyl may interact moderately with Caspase, RIP1, and p53 core domain through In-silico, possibly resulting in upregulated gene expression.

Measuring DNA modifications with the comet assay: a compendium of protocols

The comet assay is a versatile method to detect nuclear DNA damage in individual eukaryotic cells, from yeast to human. The types of damage detected encompass DNA strand breaks and alkali-labile sites (e.g., apurinic/apyrimidinic sites), alkylated and oxidized nucleobases, DNA-DNA crosslinks, UV-induced cyclobutane pyrimidine dimers and some chemically induced DNA adducts. Depending on the specimen type, there are important modifications to the comet assay protocol to avoid the formation of additional DNA damage during the processing of samples and to ensure sufficient sensitivity to detect differences in damage levels between sample groups. Various applications of the comet assay have been validated by research groups in academia, industry and regulatory agencies, and its strengths are highlighted by the adoption of the comet assay as an in vivo test for genotoxicity in animal organs by the Organisation for Economic Co-operation and Development. The present document includes a series of consensus protocols that describe the application of the comet assay to a wide variety of cell types, species and types of DNA damage, thereby demonstrating its versatility.

Assessing testicular germ cell DNA damage in the comet assay; introduction of a proof-of-concept

The in vivo comet assay is widely used to measure genotoxicity; however, the current OECD test guideline (TG 489) does not recommend using the assay to assess testicular germ cells, due to the presence of testicular somatic cells. An adapted approach to specifically assess testicular germ cells within the comet assay is certainly warranted, considering regulatory needs for germ cell-specific genotoxicity data in relation to the increasing global production of and exposure to potentially hazardous chemicals. Here, we provide a proof-of-concept to selectively analyze round spermatids and primary spermatocytes, distinguishing them from other cells of the testicle. Utilizing the comet assay recordings of DNA content (total fluorescence intensity) and DNA damage (% tail intensity) of individual comets, we developed a framework to distinguish testicular cell populations based on differences in DNA content/ploidy and appearance. Haploid round spermatid comets are identified through (1) visual inspection of DNA content distributions, (2) setting DNA content thresholds, and (3) modeling DNA content distributions using a normal mixture distribution function. We also describe an approach to distinguish primary spermatocytes during comet scoring, based on their high DNA content and large physical size. Our concept allows both somatic and germ cells to be analyzed in the same animal, adding a versatile, sensitive, rapid, and resource-efficient assay to the limited genotoxicity assessment toolbox for germ cells. An adaptation of TG 489 facilitates accumulation of valuable information regarding distribution of substances to germ cells and their potential for inducing germ cell gene mutations and structural chromosomal aberrations.

The Comparative Pharmaco- and Histokinetics of the Therapeutic Dose of Estradiol Valerate and Bromocriptine in Common Quails

The current study is aimed at examining the overall effects of steroids on the tissues of organisms and pharmacotherapeutics and pharmaco-histokinetics of several steroids, including Bromocriptine as mesylate and estradiol valerate in common quails (Coturnix coturnix). A total of 100 birds were used for pharmaco-histokinetics. The research was carried out in two separate trials, one during the fall season and the other during the spring season. Each experiment lasted for five, ten, fifteen, and twenty days. Each study group used 20 birds while basing their experiments on a control group of 5. At the stretch of five, ten, fifteen, and twenty days in each season, therapeutic dosages were administered to a sum of two groups representing two separate steroid trial groups. Each steroid was administered to each bird in a therapeutic dose, which was three drops administered twice daily. Clinical symptoms include despondency, sluggishness, and variations in weight and temperature that almost all treated birds display. However, only in trials conducted in the fall was a sizable degree of body enlargement in one treated bird noticed. The winter testing showed a mortality rate. Four birds have died in the twenty-day group. One bird died when treated with estradiol valerate, and three birds died treated with Bromocriptine as mesylate. Both the male and female birds showed signs of having lost some of their body weight. The treated birds' kidney, stomach, hearts, and livers exhibited some edema. In comparison, almost all birds show enteritis, which indicates that steroids mainly affect the intestine. There were apparent differences in the histological analysis of heart and skeletal muscle and some treated birds with the control group. The kidney, liver, and intestine show the major histopathological change in all treated birds.

High anesthetic (isoflurane) indoor pollution is associated with genetic instability, cytotoxicity, and proliferative alterations in professionals working in a veterinary hospital

This is the first study to monitor anesthetic pollution in veterinary operating rooms (VOR) and assess the toxicological impact of the inhalational anesthetic isoflurane (exposed group) compared to matched volunteers (control group). DNA damage was evaluated in mononuclear cells by the comet assay while genetic instability (including micronucleus-MN), cell proliferation, and cell death markers were assessed by the buccal MN cytome assay. Residual isoflurane concentrations in VOR (air monitoring) lacking the scavenging system were assessed by infrared spectrophotometry; the mean concentration was 11 ppm (≥ 5 times above the international recommended threshold). Comet assay results did not differ between groups; however, both younger exposed professionals (with higher week workload) compared to older individuals exposed for the same period and older professionals with greater time of exposure (years) compared to those in the same age group with fewer years of exposure presented higher DNA damage. The exposed group had a higher frequency of MN, nuclear buds, binucleated cells, karyorrhexis, and karyolysis and a lower frequency of basal cells than the control group. Exposed women were more vulnerable to genetic instability and proliferative index; exposed men presented more cytotoxicity. High WAG exposure has deleterious effects on exposed professionals.

Search for the optimal genotoxicity assay for routine testing of chemicals: Sensitivity and specificity of conventional and new test systems

Many conventional in vitro tests that are currently widely used for routine screening of chemicals have a sensitivity/specificity in the range between 60 % and 80 % for the detection of carcinogens. Most procedures were developed 30-40 years ago. In the last decades several assays became available which are based on the use of metabolically competent cell lines, improvement of the cultivation conditions and development of new endpoints. Validation studies indicate that some of these models may be more reliable for the detection of genotoxicants (i.e. many of them have sensitivity and specificity values between 80 % and 95 %). Therefore, they could replace conventional tests in the future. The bone marrow micronucleus (MN) assay with rodents is at present the most widely used in vivo test. The majority of studies indicate that it detects only 5-6 out of 10 carcinogens while experiments with transgenic rodents and comet assays seem to have a higher predictive value and detect genotoxic carcinogens that are negative in MN experiments. Alternatives to rodent experiments could be MN experiments with hen eggs or their replacement by combinations of new in vitro tests. Examples for promising candidates are ToxTracker, TGx-DDI, multiplex flow cytometry, γH2AX experiments, measurement of p53 activation and MN experiments with metabolically competent human derived liver cells. However, the realization of multicentric collaborative validation studies is mandatory to identify the most reliable tests.

Genotoxicity of Particles From Grinded Plastic Items in Caco-2 and HepG2 Cells

Large plastic litters degrade in the environment to micro- and nanoplastics, which may then enter the food chain and lead to human exposure by ingestion. The present study explored ways to obtain nanoplastic particles from real-life food containers. The first set of experiments gave rise to polypropylene nanoplastic suspensions with a hydrodynamic particle size range between 100 and 600 nm, whereas the same grinding process of polyethylene terephthalate (PET) produced suspensions of particles with a primary size between 100 and 300 nm. The exposure did not cause cytotoxicity measured by the lactate dehydrogenase (LDH) and water soluble tetrazolium 1 (WST-1) assays in Caco-2 and HepG2 cells. Nanoplastics of transparent PET food containers produced a modest concentration-dependent increase in DNA strand breaks, measured by the alkaline comet assay [net induction of 0.28 lesions/10⁶ bp at the highest concentration (95% CI: 0.04; 0.51 lesions/10⁶ base pair)]. The exposure to nanoplastics from transparent polypropylene food containers was also positively associated with DNA strand breaks [i.e., net induction of 0.10 lesions/10⁶ base pair (95% CI: −0.04; 0.23 lesions/10⁶ base pair)] at the highest concentration. Nanoplastics from grinding of black colored PET food containers demonstrated no effect on HepG2 and Caco-2 cells in terms of cytotoxicity, reactive oxygen species production or changes in cell cycle distribution. The net induction of DNA strand breaks was 0.43 lesions/10⁶ bp (95% CI: 0.09; 0.78 lesions/10⁶ bp) at the highest concentration of nanoplastics from black PET food containers. Collectively, the results indicate that exposure to nanoplastics from real-life consumer products can cause genotoxicity in cell cultures.

Systematic review on primary and secondary genotoxicity of carbon black nanoparticles in mammalian cells and animals

Carbon black exposure causes oxidative stress, inflammation and genotoxicity. The objective of this systematic review was to assess the contributions of primary (i.e. direct formation of DNA damage) and secondary genotoxicity (i.e., DNA lesions produced indirectly by inflammation) to the overall level of DNA damage by carbon black. The database is dominated by studies that have measured DNA damage by the comet assay. Cell culture studies indicate a genotoxic action of carbon black, which might be mediated by oxidative stress. Many in vivo studies originate from one laboratory that has investigated the genotoxic effects of Printex 90 in mice by intra-tracheal instillation. Meta-analysis and pooled analysis of these results demonstrate that Printex 90 exposure is associated with a slightly increased level of DNA strand breaks in bronchoalveolar lavage cells and lung tissue. Other types of genotoxic damage have not been investigated as thoroughly as DNA strand breaks, although there is evidence to suggest that carbon black exposure might increase the mutation frequency and cytogenetic endpoints. Stratification of studies according to concurrent inflammation and DNA damage does not indicate that carbon black exposure gives rise to secondary genotoxicity. Even substantial pulmonary inflammation is at best only associated with a weak genotoxic response in lung tissue. In conclusion, the review indicates that nanosized carbon black is a weak genotoxic agent and this effect is more likely to originate from a primary genotoxic mechanism of action, mediated by e.g., oxidative stress, than inflammation-driven (secondary) genotoxicity.

In vivo effects of 1,4-dioxane on genotoxic parameters and behavioral alterations in Drosophila melanogaster

1,4-Dioxane (DXN) is used as solvent in different consumer products including cosmetics, paints, surfactants, and waxes. In addition, DXN is released as an unwanted contaminating by-product as a result of some reactions including ethoxylation of alcohols, which occurs with in personal care products. Consequently, DXN pollution was detected in drinking water and is considered as an environmental problem. At present, the genotoxicity effects attributed to DXN are controversial. The present study using an in vivo model organism Drosophila melanogaster aimed to determine the toxic/genotoxic, mutagenic/recombinogenic, oxidative damage as evidenced by ROS production, phenotypic alterations as well as behavioral and developmental alterations that are closely related to neuronal functions. Data demonstrated that nontoxic DXN concentration (0.1, 0.25, 0.5, or 1%) induced mutagenic (1%) and recombinogenic (0.1, 0.25, or 0.5%) effects in wing spot test and genotoxicity in hemocytes using comet assay. The nontoxic concentrations of DXN (0.1, 0.25, 0.5, or 1%) significantly increased oxidative stress, climbing behavior, thermal sensivity and abnormal phenotypic alterations. Our findings show that in contrast to in vitro exposure, DXN using an in vivo model Drosophila melanogaster this compound exerts toxic and genotoxic effects. Data suggest that additional studies using other in vivo models are thus warranted.

RIFM fragrance ingredient safety assessment, 3-phenylpropyl acetate, CAS Registry Number 122-72-5

Therefore, the phenethyl formate MOE for the fertility endpoint can be calculated by dividing the phenethyl alcohol NOAEL in mg/kg/day by the total systemic exposure to phenethyl formate, 1000/0.00062 or 1612903.

Evaluation of the Liver and Blood Micronucleus, and Comet Assay Endpoints in a 14-Day Repeated Dose Study with Methyl Carbamate and 1, 3-Propane Sultone

The repeated-dose liver micronucleus (RDLMN) assay is a novel method for detecting genotoxic chemicals. Two carcinogens methyl carbamate (MC) and 1, 3-propane sultone (PS) were evaluated for the liver micronucleus in a 14-day repeated-dose study with Sprague Dawley rats. Additionally, micronucleated reticulocytes (MN-RET) in peripheral blood and DNA damage (alkaline comet assay) in the liver were also assessed in the same animals. Ten groups of 5 male Sprague Dawley rats were treated once daily with MC (300, 600, or 1200 mg/kg/day), PS (37.5, 75, or 150 mg/kg/day), negative control, or 3 positive controls by oral gavage for 15 days. Blood samples were collected at 3 hours after the last administration for determining MN-RET frequencies (%MN-RET), and the livers were sampled for determining the frequency of micronuclei and DNA damage. MC was negative in the comet assay, liver micronucleus assay, and reticulocyte micronucleus assay, while PS was positive in all three assays. These results are consistent with the previous genotoxic findings of MC and PS. Therefore, the liver micronucleus assay can be effectively integrated into repeated dose studies in animals. Moreover, integration of multiple genotoxicity endpoints into one study can reduce the number of animals, boost the experimental efficiency, and provides a comprehensive evaluation of the genotoxic potential of chemicals.

Validation of the 3D reconstructed human skin micronucleus (RSMN) assay: an animal-free alternative for following-up positive results from standard in vitro genotoxicity assays

In vitro test batteries have become the standard approach to determine the genotoxic potential of substances of interest across industry sectors. While useful for hazard identification, standard in vitro genotoxicity assays in 2D cell cultures have limited capability to predict in vivo outcomes and may trigger unnecessary follow-up animal studies or the loss of promising substances where animal tests are prohibited or not desired. To address this problem, a team of regulatory, academia and industry scientists was established to develop and validate 3D in vitro human skin-based genotoxicity assays for use in testing substances with primarily topical exposure. Validation of the reconstructed human skin micronucleus (RSMN) assay in MatTek Epi-200™ skin models involved testing 43 coded chemicals selected by independent experts, in four US/European laboratories. The results were analysed by an independent statistician according to predefined criteria. The RSMN assay showed a reproducibly low background micronucleus frequency and exhibited sufficient capacity to metabolise pro-mutagens. The overall RSMN accuracy when compared to in vivo genotoxicity outcomes was 80%, with a sensitivity of 75% and a specificity of 84%, and the between- and within-laboratory reproducibility was 77 and 84%, respectively. A protocol involving a 72-h exposure showed increased sensitivity in detecting true positive chemicals compared to a 48-h exposure. An analysis of a test strategy using the RSMN assay as a follow-up test for substances positive in standard in vitro clastogenicity/aneugenicity assays and a reconstructed skin Comet assay for substances with positive results in standard gene mutation assays results in a sensitivity of 89%. Based on these results, the RSMN assay is considered sufficiently validated to establish it as a ‘tier 2’ assay for dermally exposed compounds and was recently accepted into the OECD’s test guideline development program.

Lack of In Vivo Mutagenicity of Acetamide in a 13-Week Comprehensive Toxicity Study Using F344 gpt Delta Rats

Acetamide, a food contaminant, has been shown to induce hepatocellular tumors in rats. However, the mode of action underlying acetamide-induced hepatocarcinogenesis remains unclear. In the current study, we aimed to examine the possible involvement of in vivo mutagenicity in hepatocarcinogenesis of acetamide and evaluate its toxicological profile using a comprehensive medium-term toxicity study in gpt delta rats. Six-week-old male F344 gpt delta rats were given a basal diet containing 0%, 0.625%, 1.25%, or 2.5% acetamide for 13 weeks. In general toxicologic assessment, hepatotoxic parameters in serum, such as aspartate aminotransferase and alanine aminotransferase were significantly changed at the 1.25% group and higher. Histopathological examination of the liver revealed that various changes related to hepatic injury were observed at the 1.25% group and higher. Interestingly, Feulgen-positive cytoplasmic inclusion was frequently observed in hepatocytes in these groups. In the hematopoietic system, red blood cell parameters in plasma, such as mean corpuscular volume and mean corpuscular hemoglobin were significantly changed at the 1.25% group and higher, and decrease of erythroblast in the spleen was observed histopathologically in the 2.5% group. Thus, the no-observed-adverse-effect level of acetamide in this study was 0.625% (equivalent to 394 mg/kg body weight/day). In vivo mutation assays showed that acetamide induced no changes in gpt and red/gam gene mutant frequencies, even at the carcinogenic target site. In contrast, Ki67-positive hepatocytes were increased significantly at carcinogenic doses. Therefore, these results suggested that cell proliferation activity, but not mutagenicity, played crucial roles in acetamide-induced hepatocarcinogenesis in rats.

Genotoxicity of multi-walled carbon nanotube reference materials in mammalian cells and animals

Carbon nanotubes (CNTs) were the first nanomaterials to be evaluated by the International Agency for Research on Cancer (IARC). The categorization as possibly carcinogenic agent to humans was only applicable to multi-walled carbon nanotubes called MWCNT-7. Other types of CNTs were not classifiable because of missing data and it was not possible to pinpoint unique CNT characteristics that cause cancer. Importantly, the European Commission's Joint Research Centre (JRC) has established a repository of industrially manufactured nanomaterials that encompasses at least four well-characterized MWCNTs called NM-400 to NM-403 (original JRC code). This review summarizes the genotoxic effects of these JRC materials and MWCNT-7. The review consists of 36 publications with results on cell culture experiments (22 publications), animal models (9 publications) or both (5 publications). As compared to the publications in the IARC monograph on CNTs, the current database represents a significant increase as there is only an overlap of 8 publications. However, the results come mainly from cell cultures and/or measurements of DNA strand breaks by the comet assay and the micronucleus assay (82 out of 97 outcomes). A meta-analysis of cell culture studies on DNA strand breaks showed a genotoxic response by MWCNT-7, less consistent effect by NM-400 and NM-402, and least consistent effect by NM-401 and NM-403. Results from other in vitro tests indicate strongest evidence of genotoxicity for MWCNT-7. There are too few observations from animal models and humans to make general conclusions about genotoxicity.

No Increased DNA Damage Observed in the Brain, Liver, and Lung of Fetal Mice Treated With Ethylnitrosourea and Exposed to UMTS Radiofrequency Electromagnetic Fields

The widespread use of mobile phones and Wi-Fi-based communication devices makes exposure to radiofrequency electromagnetic fields (RF-EMF) unavoidable. Previous experiments have revealed the tumor-promoting effects of non-ionizing RF-EMF in adult carcinogen-treated mice in utero. To extend these investigations, we tested whether these effects are due to the co-carcinogenicity of RF-EMF which would manifest as elevated DNA damage. Similar to previous experiments, pregnant mice were exposed to RF-EMF (Universal Mobile Telecommunication System [UMTS] standard, approximately 1,960 MHz) from day 7 post-conception (p.c.) at 0 (sham), 0.04, and 0.4 W/kg SAR. At day 14 p.c., the mice were injected with the carcinogen ethylnitrosourea (ENU, 40 mg/kg). At three time-points specifically 24, 36, and 72 h later, the pregnant females were sacrificed and the fetuses (n = 24-57) were removed. A dye (cy3) specific for adenyl adducts was used to detect DNA damage by fluorescence microscopy in the brain, liver, and lung of each fetus. Compared to control (0 W/kg SAR), exposure to RF-EMF had no effect on the formation of DNA adducts in the inspected tissues. We conclude that increased adenyl formation of DNA by RF-EMF exposure is not a valid explanation for the previously reported tumor-promoting effects of RF-RMF. Our findings may help to gain a deeper insight into the biological effects of RF-EMF exposure in the context of malignancy. © 2020 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.

Lufenuron induces reproductive toxicity and genotoxic effects in pregnant albino rats and their fetuses

Insecticides and other agrochemicals have become indispensable components of the agricultural system to ensure a notable increase in crop yield and food production. As a natural consequence, chemical residues result in significantly increased contamination of both terrestrial and aquatic ecosystems. The present study evaluated the teratogenic, genotoxic, and oxidative stress effects of residual-level lufenuron exposure on pregnant rats during the organogenesis gestational period of both mother and fetus. The tested dams were divided into three groups; control (untreated), low-dose group (orally administered with 0.4 mg/kg lufenuron) and high-dose group (orally administered with 0.8 mg/kg lufenuron). The dams of the two treatment groups showed teratogenic abnormalities represented by the asymmetrical distribution of fetuses in both uterine horns, accompanied by observed resorption sites and intensive bleeding in the uterine horns, whereas their fetuses suffered from growth retardation, morphologic malformations, and skeletal deformations. Histologic examination of the liver and kidney tissues obtained from mothers and fetuses after lufenuron exposure revealed multiple histopathologic changes. DNA fragmentation and cell cycle perturbation were also detected in the liver cells of lufenuron-treated pregnant dams and their fetuses through comet assay and flow cytometry, respectively. Moreover, lufenuron-induced oxidative stress in the liver of mothers and fetuses was confirmed by the increased malondialdehyde levels and decreased levels of enzymatic antioxidants (glutathione peroxidase and superoxide dismutase). Taken together, it can be concluded that lufenuron has a great potential in exerting teratogenic, genotoxic, and oxidative stresses on pregnant rats and their fetuses upon chronic exposure to residual levels during the organogenesis gestational period. The obtained results in the present study imply that women and their fetuses may have the same risk.

Genotoxic properties of materials used for endoprostheses: Experimental and human data

Approximately 2 million endoprostheses are implanted annually and metal ions as well as particles are released into the body from the materials which are used. This review describes the results of studies concerning genotoxic damage caused by artificial joints. DNA damage leads to various adverse long-term health effects in humans including cancer. Experiments with mammalian cells showed that metal ions and particles from orthopedic materials cause DNA damage. Induction of chromosomal aberrations (CA) was found in several in vitro experiments and in studies with rodents with metals from orthopedic materials. Human studies focused mainly on induction of CA (7 studies). Only few investigations (4) concerned sister chromatid exchanges, oxidative DNA damage (2) and micronucleus formation (1). CA are a reliable biomarker for increased cancer risks in humans) and were increased in all studies in patients with artificial joints. No firm conclusion can be drawn at present if the effects in humans are due to oxidative stress and if dissolved metal ions or release particles play a role. Our findings indicate that patients with artificial joints may have increased cancer risks due to damage of the genetic material. Future studies should be performed to identify safe materials and to study the molecular mechanisms in detail.

RIFM fragrance ingredient safety assessment, p-isopropylbenzyl alcohol, CAS Registry Number 536-60-7

The existing information supports the use of this material as described in this safety assessment. p-Isopropylbenzyl alcohol was evaluated for genotoxicity, repeated dose toxicity, developmental and reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data from the read-across analog benzyl alcohol (CAS # 100-51-6) show that p-isopropylbenzyl alcohol is not expected to be genotoxic. Data from the read-across analog benzyl alcohol (CAS # 100-51-6) provide a calculated MOE >100 for the repeated dose, developmental, and local respiratory toxicity endpoints. The reproductive toxicity endpoint was evaluated using the TTC for a Cramer Class I material, and the exposure is below the TTC (0.03 mg/kg/day). Data from read-across analog benzyl alcohol (CAS # 100-51-6) provided p-isopropylbenzyl alcohol a NESIL of 5900 μg/cm² for the skin sensitization endpoint. The phototoxicity and photoallergenicity endpoints were evaluated based on UV spectra; p-isopropylbenzyl alcohol is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; p-isopropylbenzyl alcohol was found not to be a PBT as per the IFRA Environmental Standards, and its risk quotients, based on its current volume of use in Europe and North America (i.e., PEC/PNEC) are <1.

The food contaminant acetamide is not an in vivo clastogen, aneugen, or mutagen in rodent hematopoietic tissue

Acetamide (CAS 60-35-5) is classified by IARC as a Group 2B, possible human carcinogen, based on the induction of hepatocellular carcinomas in rats following chronic exposure to high doses. Recently, acetamide was found to be present in a variety of human foods, warranting further investigation. The regulatory body JECFA has previously noted conflicting reports on acetamide's ability to induce micronuclei (MN) in mice in vivo. To better understand the potential in vivo genotoxicity of acetamide, we performed acute MN studies in rats and mice, and a subchronic study in rats, the target species for liver cancer. In the acute exposure, animals were gavaged with water vehicle control, 250, 1000, or 2000 mg/kg acetamide, or the positive control (1 mg/kg mitomycin C). In the subchronic assay, bone marrow of rats gavaged at 1000 mg/kg/day (limit dose) for 28 days was evaluated. Both acute and subchronic exposures showed no change in the ratio of polychromatic to total erythrocytes (P/E) at any dose, nor was there any increase in the incidence of micronucleated polychromatic erythrocytes (MN-PCE). Potential mutagenicity of acetamide was evaluated in male rats gavaged with vehicle control or 1500 mg/kg/day acetamide using the in vivoPig-a gene mutation assay. There was no increase in mutant red blood cells or reticulocytes in acetamide-treated animals. In both acute and sub-chronic studies, elevated blood plasma acetamide in treated animals provided evidence of systemic exposure. We conclude based on this study that acetamide is not clastogenic, aneugenic, or mutagenic in vivo in rodent hematopoietic tissue warranting a formal regulatory re-evaluation.

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In vivo micronucleus tests with acetamide in mice and rats.

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Acetamide blood plasma levels demonstrated evidence of exposure.

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Acetamide does not induce micronuclei in rats and mice.

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Acetamide does not increase mutations in the rat Pig-a gene mutation assay.

Garlic (Allium sativum L.): A Brief Review of Its Antigenotoxic Effects

Traditional Medicine/Complementary and Alternative Medicine is a practice that incorporates medicine based on plants, animals, and minerals for diagnosing, treating, and preventing certain diseases, including chronic degenerative diseases such as obesity, diabetes, hypertension, atherosclerosis, and cancer. Different factors generate its continued acceptance, highlighting its diversity, easy access, low cost, and the presence of relatively few adverse effects and, importantly, a high possibility of discovering antigenotoxic agents. In this regard, it is known that the use of different antigenotoxic agents is an efficient alternative to preventing human cancer and that, in general, these can act by means of a combination of various mechanisms of action and against one or various mutagens and/or carcinogens. Therefore, it is relevant to confirm its usefulness, efficacy, and its spectrum of action through different assays. With this in mind, the present manuscript has as its objective the compilation of different investigations carried out with garlic that have demonstrated its genoprotective capacity, and that have been evaluated by means of five of the most outstanding tests (Ames test, sister chromatid exchange, chromosomal aberrations, micronucleus, and comet assay). Thus, we intend to provide information and bibliographic support to investigators in order for them to broaden their studies on the antigenotoxic spectrum of action of this perennial plant.

The comet assay in animal models: From bugs to whales - (Part 2 Vertebrates)

The comet assay has become one of the methods of choice for the evaluation and measurement of DNA damage. It is sensitive, quick to perform and relatively affordable for the evaluation of DNA damage and repair at the level of individual cells. The comet assay can be applied to virtually any cell type derived from different organs and tissues. Even though the comet assay is predominantly used on human cells, the application of the assay for the evaluation of DNA damage in yeast, plant and animal cells is also quite high, especially in terms of biomonitoring. The present extensive overview on the usage of the comet assay in animal models will cover both terrestrial and water environments. The first part of the review was focused on studies describing the comet assay applied in invertebrates. The second part of the review, (Part 2) will discuss the application of the comet assay in vertebrates covering cyclostomata, fishes, amphibians, reptiles, birds and mammals, in addition to chordates that are regarded as a transitional form towards vertebrates. Besides numerous vertebrate species, the assay is also performed on a range of cells, which includes blood, liver, kidney, brain, gill, bone marrow and sperm cells. These cells are readily used for the evaluation of a wide spectrum of genotoxic agents both in vitro and in vivo. Moreover, the use of vertebrate models and their role in environmental biomonitoring will also be discussed as well as the comparison of the use of the comet assay in vertebrate and human models in line with ethical principles. Although the comet assay in vertebrates is most commonly used in laboratory animals such as mice, rats and lately zebrafish, this paper will only briefly review its use regarding laboratory animal models and rather give special emphasis to the increasing usage of the assay in domestic and wildlife animals as well as in various ecotoxicological studies.

A comparison of transgenic rodent mutation and in vivo comet assay responses for 91 chemicals

A database of 91 chemicals with published data from both transgenic rodent mutation (TGR) and rodent comet assays has been compiled. The objective was to compare the sensitivity of the two assays for detecting genotoxicity. Critical aspects of study design and results were tabulated for each dataset. There were fewer datasets from rats than mice, particularly for the TGR assay, and therefore, results from both species were combined for further analysis. TGR and comet responses were compared in liver and bone marrow (the most commonly studied tissues), and in stomach and colon evaluated either separately or in combination with other GI tract segments. Overall positive, negative, or equivocal test results were assessed for each chemical across the tissues examined in the TGR and comet assays using two approaches: 1) overall calls based on weight of evidence (WoE) and expert judgement, and 2) curation of the data based on a priori acceptability criteria prior to deriving final tissue specific calls. Since the database contains a high prevalence of positive results, overall agreement between the assays was determined using statistics adjusted for prevalence (using AC1 and PABAK). These coefficients showed fair or moderate to good agreement for liver and the GI tract (predominantly stomach and colon data) using WoE, reduced agreement for stomach and colon evaluated separately using data curation, and poor or no agreement for bone marrow using both the WoE and data curation approaches. Confidence in these results is higher for liver than for the other tissues, for which there were less data. Our analysis finds that comet and TGR generally identify the same compounds (mainly potent mutagens) as genotoxic in liver, stomach and colon, but not in bone marrow. However, the current database content precluded drawing assay concordance conclusions for weak mutagens and non-DNA reactive chemicals.

Assessment of the Pig-a, micronucleus, and comet assay endpoints in rats treated by acute or repeated dosing protocols with procarbazine hydrochloride and ethyl carbamate

The utility and sensitivity of the newly developed flow cytometric Pig-a gene mutation assay have become a great concern recently. In this study, we have examined the feasibility of integrating the Pig-a assay as well as micronucleus and Comet endpoints into acute and subchronic general toxicology studies. Male Sprague-Dawley rats were treated for 3 or 28 consecutive days by oral gavage with procarbazine hydrochloride (PCZ) or ethyl carbamate (EC) up to the maximum tolerated dose. The induction of CD59-negative reticulocytes and erythrocytes, micronucleated reticulocytes in peripheral blood, micronucleated polychromatic erythrocytes in bone marrow, and Comet responses in peripheral blood, liver, kidney, and lung were evaluated at one, two, or more timepoints. Both PCZ and EC produced positive responses at most analyzed timepoints in all tissue types, both with the 3-day and 28-day treatment regimens. Furthermore, comparison of the magnitude of the genotoxicity responses indicated that the micronucleus and Comet endpoints generally produced greater responses with the higher dose, short-term treatments in the 3-day study, while the Pig-a assay responded better to the cumulative effects of the lower dose, but repeated subchronic dosing in the 28-day study. Collectively, these results indicate that integration of several in vivo genotoxicity endpoints into a single routine toxicology study is feasible and that the Pig-a assay may be particularly suitable for integration into subchronic dose studies based on its ability to accumulate the mutations that result from repeated treatments. This characteristic may be especially important for assaying lower doses of relatively weak genotoxicants. Environ. Mol. Mutagen. 60:56-71, 2019. © 2018 Wiley Periodicals, Inc.

The Comet Assay: Assessment of In Vitro and In Vivo DNA Damage

Anthropogenic activities, indiscriminate and rapid industrialization as well as pursuance of a better life has led to an increase in the concentration of chemicals, like pesticides, automobile exhausts, and new chemical entities, in the environment, which have an adverse effect on all living organisms including humans. Sensitive and robust test systems are thus required for accurate hazard identification and risk assessment. The Comet assay has been used widely as a simple, rapid, and sensitive tool for assessment of DNA damage in single cell from both in vitro and in vivo sources as well as in humans. The advantages of the in vivo Comet assay are its ability to detect DNA damage in any tissues, despite having non-proliferating cells, and its sensitivity to detect genotoxicity. The recommendations from the international workshops held for the Comet assay have resulted in establishment of guidelines, and the OECD has adopted a guideline for the in vivo Comet assay as a test for assessing DNA damage in animals. The in vitro Comet assay conducted in cultured cells can be used for screening large number of compounds and at very low concentrations. The in vitro assay has also been automated to provide a high throughput screening method for new chemical entities, as well as in environmental samples. This chapter details the in vitro Comet assay using the 96-well plate and in vivo Comet assay in multiple organs of the mouse.

Evidence of Some Natural Products with Antigenotoxic Effects. Part 2: Plants, Vegetables, and Natural Resin

Cancer is one of the leading causes of death worldwide. The agents capable of causing damage to genetic material are known as genotoxins and, according to their mode of action, are classified into mutagens, carcinogens, or teratogens. Genotoxins are also involved in the pathogenesis of several chronic degenerative diseases, including hepatic, neurodegenerative, and cardiovascular disorders; diabetes; arthritis; cancer; chronic inflammation; and ageing. In recent decades, researchers have found novel bioactive phytocompounds able to counteract the effects of physical and chemical mutagens. Several studies have shown the antigenotoxic potential of different fruits and plants (Part 1). In this review (Part 2), we present a research overview conducted on some plants and vegetables (spirulina, broccoli, chamomile, cocoa, ginger, laurel, marigold, roselle, and rosemary), which are frequently consumed by humans. In addition, an analysis of some phytochemicals extracted from those vegetables and the analysis of a resin (propolis),whose antigenotoxic power has been demonstrated in various tests, including the Ames assay, sister chromatid exchange, chromosomal aberrations, micronucleus, and comet assay, was also performed.

The comet assay: ready for 30 more years

During the last 30 years, the comet assay has become widely used for the measurement of DNA damage and repair in cells and tissues. A landmark achievement was reached in 2016 when the Organization for Economic Co-operation and Development adopted a comet assay guideline for in vivo testing of DNA strand breaks in animals. However, the comet assay has much more to offer than being an assay for testing DNA strand breaks in animal organs. The use of repair enzymes increases the range of DNA lesions that can be detected with the assay. It can also be modified to measure DNA repair activity. Still, despite the long-term use of the assay, there is a need for studies that assess the impact of variation in specific steps of the procedure. This is particularly important for the on-going efforts to decrease the variation between experiments and laboratories. The articles in this Special Issue of Mutagenesis cover important technical issues of the comet assay procedure, nanogenotoxicity and ionising radiation sensitivity on plant cells. The included biomonitoring studies have assessed seasonal variation and certain predictors for the basal level of DNA damage in white blood cells. Lastly, the comet assay has been used in studies on genotoxicity of environmental and occupational exposures in human biomonitoring studies and animal models. Overall, the articles in this Special Issue demonstrate the versatility of the comet assay and they hold promise that the assay is ready for the next 30 years.

Comprehensive Review of Quality of Publications and Meta-analysis of Genetic Damage in Mammalian Cells Exposed to Non-Ionizing Radiofrequency Fields

There have been numerous published studies reporting on the extent of genetic damage observed in animal and human cells exposed in vitro and in vivo to non-ionizing radiofrequency fields (RF, electromagnetic waves that carry energy as they propagate in air and dense media). Overall, the data are inconsistent; while some studies have suggested significantly increased damage in cells exposed to RF energy compared to unexposed and/or sham-exposed control cells, others have not. Several variables in exposure conditions used in the experiments might have contributed to the controversy. In this comprehensive review, four specific quality control measures were used to determine the quality of 225 published studies in animal and human cells exposed in vitro and in vivo to RF energy, and the results from 2,160 tests with different sample sizes were analyzed. The four specific quality control measures were as follows: 1. "Blind" collection/analysis of the data to eliminate individual/observer "bias"; 2. Adequate description of "dosimetry" for independent replication/confirmation; 3. Inclusion of "positive controls" to confirm the outcomes; and 4. Inclusion of "sham-exposed controls" which are more appropriate to compare the data with those in RF exposure conditions. In addition, meta-analysis of the genetic damage in cells exposed to RF energy and control cells, thus far available in the RF literature database, was performed to obtain the "d" values, i.e., standardized mean difference between these two types of cells or the effect size. The relationship between d values and the above-mentioned quality control measures was ascertained. In addition, the correlation between the quality control measures and the conclusions reported in the publications (no significant difference between the cells exposed to RF energy and control cells; increased damage in former cells compared to the latter; increased, no significant difference and decreased damage in cells exposed to RF energy in the same experiment; or decreased damage in cells exposed to RF energy) was examined. The overall conclusions were as follows: 1. When all four quality control measures were mentioned in the publication, the d values were smaller compared to those when one or more quality control measures were not mentioned in the investigation; 2. Based on the inclusion of quality control measures, the weighted outcome in cells exposed to RF energy (d values) indicated a very small effect, if any; 3. The number of published studies reporting no significant difference in genetic damage of cells exposed to RF energy, compared to that of control cells, increased with increased number of quality control measures employed in investigations; 4. The number of published studies reporting increased genetic damage in cells exposed to RF energy decreased with increased number of quality control measures; and 5. There was a "bias" towards the publications reporting increased genetic damage in cells exposed to RF energy even with very small sample size. Overall, the results from this study underscore the importance of including quality control measures in investigations so that the resulting data are useful, nationally and internationally, in evaluating "potential" health risks from exposure to RF energy.

Impact of obesity and overweight on DNA stability: Few facts and many hypotheses

Health authorities are alarmed worldwide about the increase of obesity and overweight in the last decades which lead to adverse health effects including inflammation, cancer, accelerated aging and infertility. We evaluated the state of knowledge concerning the impact of elevated body mass on genomic instability. Results of investigations with humans (39 studies) in which DNA damage was monitored in lymphocytes and sperm cells, are conflicting and probably as a consequence of heterogeneous study designs and confounding factors (e.g. uncontrolled intake of vitamins and minerals and consumption of different food types). Results of animal studies with defined diets (23 studies) are more consistent and show that excess body fat causes DNA damage in multiple organs including brain, liver, colon and testes. Different molecular mechanisms may cause genetic instability in overweight/obese individuals. ROS formation and lipid peroxidation were found in several investigations and may be caused by increased insulin, fatty acid and glucose levels or indirectly via inflammation. Also reduced DNA repair and formation of advanced glycation end products may play a role but more data are required to draw firm conclusions. Reduction of telomere lengths and hormonal imbalances are characteristic for overweight/obesity but the former effects are delayed and moderate and hormonal effects were not investigated in regard to genomic instability in obese individuals. Increased BMI values affect also the activities of drug metabolizing enzymes which activate/detoxify genotoxic carcinogens, but no studies concerning the impact of these alterations of DNA damage in obese individuals are available. Overall, the knowledge concerning the impact of increased body weight and DNA damage is poor and further research is warranted to shed light on this important issue.

Assessment of DNA damages in lymphocytes of agricultural workers exposed to pesticides by comet assay in a cross-sectional study

PURPOSE

To assess the predictive power of the comet assay in the context of occupational exposure to pesticides.

MATERIALS AND METHODS

The recruited subjects completed a structured questionnaire and gave a blood sample. Exposure to pesticides was measured by means of an algorithm based on Dosemeci's work (Agricultural Health Study). Approximately 50 images were analyzed for each sample via fluorescence microscopy. The extent of DNA damage was estimated by tail moment (TM) and is the product of tail DNA (%) and tail Length.

RESULTS

Crude significant risks (odds ratios, ORs) for values higher than the 75th percentile of TM were observed among the exposed subjects (score > 1). The frequency of some confounding factors (sex, age and smoking) was significantly higher among the exposed workers. A significant dose-effect relationship was observed between TM and exposure score. Significant high-risk estimates (ORs), adjusted by the studied confounding factors, among exposure to pesticides and TM, % tail DNA and tail length were confirmed using unconditional logistic regression models.

CONCLUSIONS

The adjusted associations (ORs) between the comet parameters and exposure to pesticides were significant. The sensitivity of the comet test was low (41%), the specificity (89%) and the predictive positive value (0.77) were found acceptable.

Clinical and genomic safety of treatment with Ginkgo biloba L. leaf extract (IDN 5933/Ginkgoselect®Plus) in elderly: a randomised placebo-controlled clinical trial [GiBiEx]

BACKGROUND

Numerous health benefits have been attributed to the Ginkgo biloba leaf extract (GBLE), one of the most extensively used phytopharmaceutical drugs worldwide. Recently, concerns of the safety of the extract have been raised after a report from US National Toxicology Program (NTP) claimed high doses of GBLE increased liver and thyroid cancer incidence in mice and rats. A safety study has been designed to assess, in a population of elderly residents in nursing homes, clinical and genomic risks associated to GBLE treatment.

METHODS

GiBiEx is a multicentre randomized clinical trial, placebo controlled, double blinded, which compared subjects randomized to twice-daily doses of either 120-mg of IDN 5933 (also known as Ginkgoselect®Plus) or to placebo for a 6-months period. IDN 5933 is extracted from dried leaves and contains 24.3% flavone glycosides and 6.1% of terpene lactones (2.9% bilobalide, 1.38% ginkgolide A, 0.66% ginkgolide B, 1.12% ginkgolide C) as determined by HPLC. The study was completed by 47 subjects, 20 in the placebo group and 27 in the treatment group. Clinical (adverse clinical effect and liver injury) and genomic (micronucleus frequency, comet assay, c-myc, p53, and ctnnb1 expression profile in lymphocytes) endpoints were assessed at the start and at the end of the study.

RESULTS

No adverse clinical effects or increase of liver injury markers were reported in the treatment group. The frequency of micronuclei [Mean Ratio (MR) = 1.01, 95% Confidence Intervals (95% CI) 0.86-1.18), and DNA breaks (comet assay) (MR = 0.91; 95% CI 0.58-1.43), did not differ in the two study groups. No significant difference was found in the expression profile of the three genes investigated.

CONCLUSIONS

None of the markers investigated revealed a higher risk in the treatment group, supporting the safety of IDN 5933 at doses prescribed and for duration of six months.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03004508 , December 20, 2016. Trial retrospectively registered.

Enhancement of Uterine Cancer Development after Oocyte Depletion by Juvenile Exposure to Gamma Radiation in Rats: - A Comparative Study on Sensitivity of Damage to Female Reproductive Organs by Radiation between Juvenile and Adulthood Using a Rat Model

To clarify sensitivities of juvenile exposure to radiation on uterine carcinogenesis, female Donryu rats, a high yield strain of uterine corpus cancer, were exposed to 0.2 and 1.0 Gy of gamma radiation at postnatal day 14. Sequential changes in their reproductive organs and hematology, and the effects on uterine tumor development were compared to those in adult rats exposed to the same doses. Half number of the rats in each group was treated with N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) after the radiation to accelerate the development of uterine cancer. Severe apoptosis and depletion of oocytes in the primordial/primary follicles were immediately induced after juvenile exposure at 1.0 Gy only. The ovaries in rats exposed to 1.0 Gy at juvenile showed severe atrophy characterized by the loss of all types of follicles and a lack of corpora lutea by 2 months of age, and all rats elicited an early onset of persistent estrus corresponding to the atrophy. At the termination of 9 months of age, juvenile 1.0 Gy exposure with ENNG treatment increased the incidence of endometrial adenocarcinoma and the multiplicities of combined endometrial adenocarcinomas and their precancerous lesions. Enhancement of uterine cancer development was not apparent at the same exposure without ENNG. In comet assays, neither 0.2 nor 1.0 Gy juvenile exposure induced direct DNA damage to uteri though the damage was found in the ovary at 1.0 Gy. The present results indicated that juvenile exposure to gamma radiation indirectly enhanced uterine cancer development in rats through direct damage to oocytes resulting in serious atrophy of the ovary accompanying early onset of persistent estrus. The damage to ovary was more sensitive at juvenile than adults. The result in comet assay suggested that direct DNA damage to the uterus by radiation was excluded.

Genetic Alterations in Pesticide Exposed Bolivian Farmers An evaluation by analysis of chromosomal aberrations and the comet assay

Background

Pesticides are of concern in Bolivia because of increasing use. Frequent intoxications have been demonstrated due to use of very toxic pesticides, insufficient control of distribution and sale and little knowledge among farmers of protective measures and hygienic procedures.

Method

Questionnaires were applied and blood tests taken from 81 volunteers from La Paz County, of whom 48 were pesticide exposed farmers and 33 non-exposed controls. Sixty males and 21 females participated with a mean age of 37.3 years (range 17–76). Data of exposure and possible genetic damage were collected and evaluated by well known statistical methods, controlling for relevant confounders. To measure genetic damage chromosomal aberrations and the comet assay analysis were performed.

Results

Pesticide exposed farmers had a higher degree of genetic damage compared to the control group. The number of chromosomal aberrations increased with the intensity of pesticide exposure. Females had a lower number of chromosomal aberrations than males, and people living at altitudes above 2500 metres seemed to exhibit more DNA damage measured by the comet assay.

Conclusions

Bolivian farmers showed signs of genotoxic damage, probably related to exposure to pesticides. Due to the potentially negative long term health effects of genetic damage on reproduction and the development of cancer, preventive measures are recommended. Effective control with imports and sales, banning of the most toxic pesticides, education and information are possible measures, which could help preventing the negative effects of pesticides on human health and the environment.