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Studies in farmers suggest a possible role of pesticides in the occurrence of Central Nervous System (CNS) tumors but scientific evidence is still insufficient. Using data from the French prospective agricultural cohort AGRICAN (Agriculture & Cancer), we investigated the associations between exposure of farmers and pesticide users to various kinds of crops and animal farming and the incidence of CNS tumors, overall and by subtypes. Over the 2005-2007, 181,842 participants completed the enrollment questionnaire that collected a complete job calendar with lifetime history of farming types. Associations were estimated using proportional hazards models with age as underlying timescale. During a 5.2 years average follow-up, 273 incident cases of CNS tumors occurred, including 126 gliomas and 87 meningiomas. Analyses showed several increased risks of CNS tumors in farmers, especially in pesticide users (hazard ratio = 1.96; 95% confidence interval: 1.11-3.47). Associations varied with tumor subtypes and kinds of crop and animal farming. The main increases in risk were observed for meningiomas in pig farmers and in farmers growing sunflowers, beets and potatoes and for gliomas in farmers growing grasslands. In most cases, more pronounced risk excesses were observed among pesticide applicators. Even if we cannot completely rule out the contribution of other factors, pesticide exposures could be of primary concern to explain these findings.

Thiophene derivatives, a class of compounds widely used in products such as pharmaceuticals, agrochemicals or dyestuffs, represent chemicals of concern. Indeed, the thiophene ring is often considered as a structural moiety that may be involved in toxic effects in humans. We primarily focus on the genotoxic/mutagenic and carcinogenic potentials of the methyl 3-amino-4-methylthiophene-2-carboxylate (1), a precursor of the articaine local anesthetic (4) which falls within the scope of the European REACH (Registration, Evaluation, Authorisation and restriction of CHemicals) legislation. To discern some structure-toxicity relationships, we also studied two related compounds, namely the 3-amino 4-methylthiophene (2) and the 2-acetyl 4-chlorothiophene (3). Techniques employed to assess mutagenic and DNA-damaging effects involved the Salmonella mutagenicity assay (or Ames test) and the single-cell gel electrophoresis assay (or Comet assay). In the range of tested doses, none of these derivatives led to a positive response in the Ames tests and DNA damage was only observed in the Comet assay after high concentration exposure of 2. The study of their carcinogenic potential using the in vitro SHE (Syrian Hamster Embryo) cell transformation assay (CTA) highlighted the activity of compound 2. A combination of experimental data with in silico predictions of the reactivity of thiophene derivatives towards cytochrome P450 (CYP450), enabled us to hypothesize possible pathways leading to these toxicological profiles.

BCL-2/JH rearrangement has been proposed as a biomarker for evaluating the genotoxicity of occupational and environmental exposures. Available data on time-related modification of this rearrangement in peripheral blood lymphocytes in unexposed healthy individuals is scarce. We investigated the characteristics of BCL-2/JH rearrangements in 33 adults unexposed to genotoxins at 2 seasonal time points: winter and spring. BCL-2/JH rearrangement was detected in 79% of individuals (detection limit = 8.48 × 10−8). Its frequency ranged from

Acute myeloid leukaemia (AML) cases with different chromosomal abnormalities may reflect different aetiologies. Benzene exposure, from a number of sources including smoking, is one risk factor for AML. Individual susceptibility to benzene may depend on differences in expression of metabolizing enzymes. We tested the hypothesis that smoking as well as genetic polymorphisms in the microsomal epoxide hydrolase gene (HYL1), an enzyme involved in benzene metabolism, could be risk factors for AML with defined chromosomal abnormalities. Twenty-six AML cases with ?7/del(7q) and 24 cases with t(8;21), as well as 43 cases with normal karyotype and 155 age-, sex- and residence-matched controls, were drawn from a large case–control study on adult acute leukaemia. Current smoking was significantly associated with the cytogenetic abnormalities t(8;21) or ?7/del(7q) (OR = 4·9; 95%CI = 2·1–11·5) but not with a normal karyotype, relative to individuals who were not current smokers. A putative high activity HYL1 phenotype [exon 3, residue 113 (Tyr/Tyr) and exon 4, residue 139 (His/Arg or Arg/Arg)] was associated with a significantly increased AML risk in men with ?7/del(7q) or t(8;21) (OR = 4·4; 95%CI 1·1–17·0) but not with a normal karyotype. This suggests that AML cases with defined chromosomal abnormalities could be related to specific carcinogen exposures and, furthermore, suggests that smoking and genetic polymorphisms in HYL1 could be risk factors for AML with ?7/del(7q) or t(8;21).

Background: The ability of the comet assay to quantify DNA strand breaks and alkali labile sites has been widely demonstrated. In this study, this assay was tested for its ability to identify DNA fragmentation occurring during apoptosis in comparison with standard DNA flow cytometry analysis. Methods: Staurosporine-induced apoptosis in CHO cells is an adequate model to study a rapid time- and dose-dependent appearance of this process. Results: Nuclear staining with DAPI confirmed the induction of apoptosis with a typical chromatin condensation and fragmentation. Analysis of propidium-iodide- (PI) stained DNA by flow cytometry showed the presence of a pre-G1 peak, characteristic of apoptotic cells, 6 h after drug treatment. The detection of highly damaged cells (HDC) by the comet assay after 3 h treatment occurred earlier than the detection of apoptotic cells by flow cytometry. However, HDC were missed when the DNA fragmentation was too high, preventing accurate quantification of late apoptotic cells. Conclusions: The comet assay is more sensitive than standard DNA flow cytometry to detect early DNA fragmentation events occurring during apoptosis. However, the comet assay modified by omitting electrophoresis was necessary to quantify apoptotic fraction at later stages. Cytometry 36: 117–122, 1999. © 1999 Wiley-Liss, Inc.