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A mortality study was carried out among workers employed in the Arcelor and GTS Industries plants in Dunkerque. It was aimed at assessing the possible association between iron oxide exposures and lung cancer risk. The cohort comprised 16,742 males and 959 females. Among males, the observed mortality was lower than expected for all causes. No significant lung cancer excess was observed for exposure to iron oxides and no dose-response relationship with intensity and duration of exposure.

With exponentially growing EMT6 mouse tumour cells in vitro, we have compared the effects of a dose of ionizing radiation and different temperature-time combinations on the lengths of the cell cycle and of mitosis using time-lapse cinematography on individual cells. The radiation dose and various temperature-time combinations all produced 50 per cent lethality. The hyperthermia treatments between 42 and 45°C all caused a mitosis delay (MD) which was greater than that induced by ionizing radiation. The MD was greater with increasing temperature.In contrast, hyperthermia also induced a mitosis lengthening (ML) but this was only of the same order of magnitude as radioinduced ML. The results argue in favour of different mechanisms underlying thermoinduced MD and ML.

Exponentially growing cultures of EMT 6 cells were irradiated in vitro with neon ions, helium ions or 60Co γ-rays. Time-lapse cinematography allowed the determination, for individual cells, of cycle duration, success of the mitotic division and the age of the cell at the moment of irradiation. Irradiation induced a significant mitotic delay increasing proportionally with the delivered dose. Using mitotic delay as an endpoint, the r.b.e. for neon ions with respect to 60Co γ-rays was 3·3 ± 0·2 while for helium ions it was 1·2 ± 0·1. Mitotic delay was greatest in those cells that had progressed furthest in their cycle at the time of irradiation. No significant mitotic delay was observed in the post-irradiation generation. Division probability was significantly reduced by irradiation both in the irradiated and in the post-irradiated generation. The reduction in division probability obtained with 3 Gy of neon ions was similar to that obtained after irradiation with 6 Gy of helium ions or 60Co γ-rays.

The effects of handling antineoplastic drugs were examined in 17 nurses working in a pneumology department in a hospital in the Paris area. Twenty-five others in the same department who were not handling such drugs acted as controls. Exposure to antineoplastic drugs was evaluated by questionnaire and by assessment of urine mutagenicity. The cytogenetic repercussions of exposure were assessed by examining sister chromatid exchanges and chromosomal abnormalities in circulating lymphocytes. The urine of the exposed nurses was significantly more mutagenic than that of the controls. No cytogenetic abnormalities were revealed in the exposed subjects since both these and the control nurses exhibited similar frequencies of chromosomal abnormalities and similar average numbers of sister chromatid exchanges in circulating lymphocytes. However, in smokers, the urine was significantly more mutagenic compared to that of nonsmokers, chromosomal abnormalities were twice as frequent, and the number of sister chromatid exchanges was significantly larger. Comparison of these results with the findings of other authors suggests that the moderate exposure to antineoplastic drugs prevailing in this pneumology department (i.e., an average of about 11 infusions per week) does not cause detectable cytogenetic abnormalities even though it significantly increases urine mutagenicity.

The in situ spatial distribution of nucleolus-organizing-region (NOR) bearing chromosomes in relation to the inactive X chromosome was studied during interphase in human fibroblasts. The respective positions of these chromosomes were examined in 30 growing and 32 resting fibroblasts from reconstructed nuclei, using nucleoli and the Barr body as ultrastructural markers. Experimental values for the distance between the nucleoli and the Barr body were estimated by their coefficient of closeness and compared to the uniform distribution. The following results were obtained: (1) the distribution patterns for the two populations of nuclei were similar, (2) the distribution of the NOR-bearing chromosomes in relation to the inactive X chromosome varied and differed significantly from a uniform distribution, and (3) in many cases the Barr body was observed to be in a juxta-nucleolar position. The internal distribution revealed by this study is compared with the data in the literature, especially with the conflicting data obtained by other methods used to determine the interphase arrangement of chromosomes. The relationship between interphase and metaphase arrangements such as can be deduced with these methods, is discussed in relation to the mechanisms of the formation of metaphase plates or chromatid translocations.

A cohort study was conducted in a French battery factory in 1977–1982 to explore the relationship between occupational lead exposure and fertility. A total of 354 battery workers, divided into 229 lead-exposed subjects (corresponding with 886 person-years) and 125 non-lead-exposed subjects (corresponding with 598 person-years) were compared, in a person-year analysis, for the risk of infertilitiy. Lead exposure, at any level of absorption, did not appear significantly associated with a reduction in fertility after controlling for potential confounders: age, French origin, educational level, number of children at start of the period, cigarette smoking and exposure to heat. The apparent inconsistency between our results and those of several studies involving biological data and semen analysis is partially explained by recent knowledge relating to predictive value on the pregnancy of semen abnormalities.

In oocytes of Pleurodeles waltlii, the method of Miller and Beatty has been combined with a method of high-resolution autoradiography especially suitable for the study of isolated molecules. In vitro labeling of RNA by tritiated precursors was carried out with increasing incubation times (1, 4, 15, 24, 48, and 72 h). Silver grains were present over ribonucleoprotein fibrils in amounts sufficient for quantitative analysis of nucleolar DNA transcription. Statistical analysis of the data revealed that: (a) The units of any one nucleolus exhibited a large degree of heterogeneity in their number of grains. (b) There was a parallelism between the increasing grain number and the ribonucleoprotein-fibril lengthening as observed along the transcription unit.

The spatial organization of the two nucleolus-organizing region(NOR)-bearing chromosomes during interphase was studied in Aotus trivirgatus fibroblasts, using nucleoli as ultrastructural markers. Their distribution was examined by measuring the distances between them in 30 reconstructed nuclei, and comparing these experimental values with the theoretical ones obtained by simulation. Results were as follows: (1) the nucleoli are arranged in a polarized manner inside the nucleus; (2) the nucleoli are tightly bound to the nuclear envelope at two opposites sites; (3) the distance between the two nucleoli is variable, and is shorter than it would be if the two nucleoli were distributed at random. These findings indicate that the NOR-bearing chromosomes are fixed at the nuclear envelope in two opposite areas. They are also consistent with the hypothesis that each chromosome occupies a separate domain inside the nucleus. They can be interpreted according to the model in which chromosome arrangement within the interphase nucleus is based on the separation of the diploid complement into two independent haploid sets.

Une exposition précoce aux animaux de ferme pourrait protéger des leucémies de l’enfant, comme c’est le cas pour les allergies, par maturation effective du système immunitaire naïf. L’objectif de notre étude est d’étudier en France le lien entre les expositions précoces aux animaux, les allergies et le risque de leucémie de l’enfant.

The relationships between occupational risk factors in France and bladder cancer were assessed from a hospital-based case-control study conducted between 1984 and 1987 in five regions representing various industries, including mining, textile manufacture, metallurgy and the production of rubber and chemicals. The study concerned 765 cases (668 men and 107 women) and the same number of controls. Odds ratios (OR) adjusted for matching variables (age, place of residence and hospital), and tobacco smoking were estimated by unconditional logistic regression. A significantly in creased risk of bladder cancer was observed among men employed in coal mining (OR=2.42; 95% confidence interval (Cl): 1.25–4.67) and the chemicals industry (OR%2.36; 95% Cl: 1.23–4.53). Aircraft and ship's officers (OR%11.8; 95% Cl: 1.46–95.7), managers (OR%1.64; 95% Cl: 1.11–2.43) and street vendors (OR%3.60; 95% Cl: 1.15–11.3) also had an increased risk. Among women, employment in the clothing industry was associated with a high OR (%3.21; 95% Cl: 1.34–7.71). Assessment of individual exposures by a panel of industrial hygiene experts showed that significantly more cases than controls had been exposed to the following substances: chlorinated solvents (OR%1.86; 95% Cl: 1.19–2.90), industrial oils and greases (OR%1.44; 95% CI: 1.10–1.89), welding fumes (OR%1.40; 95% Cl: 0.98–2.01), coal dust (OR%1.71; 95% Cl: 1.02–2.89) and metallic oxide dust (OR%2.99; 95% Cl: 1.12–8.01). The high risks observed for coal mining, petroleum refining, the tool and die, glass and chemicals industries, steel foundries, car manufacture and car repair are consistent with the possibility that exposure to polycyclic aromatic hydrocarbons is a risk factor for bladder cancer.

The hypothesis of the existence of spatial variations of spontaneous abortion rates has two logical consequences on dizygotic twinning rates: they must be heterogeneously distributed and show a positive correlation with natality. French data available on dizygotic twinning rates from 1950 to 1974 are in agreement with both implications. Although alternative explanations are possible, these findings do reinforce the relevance of dizygotic twinning rate variations as a tool for the assessment of reproduction failures.