Effect of cadmium on reproduction of daphnids in a small aquatic microcosm.

Chlorella vulgaris colonies were grown as nutrient agar for one week, followed by addition of Daphnia magna in overlying water for a second week. A range of concentrations of cadmium were added to the Chlorella or to the Chlorella followed by higher cadmium concentrations in the overlying fluid. A dose-dependent reduction in reproduction was observed with increased cadmium. When parent daphnids were first exposed to a lower cadmium concentration, and their offspring of preconditioned juvenile daphnids then exposed to a higher concentration, cadmium tolerance in new-born daphnids was observed.

Acrolein toxicity: comparative in vitro study with lung slices and pneumocytes type II cell line from rats.

Toxicological effects of acrolein have been studied in precision-cut rat lung slices and in L2 cells, a rat pneumocyte II cell line. These two models were cultured for 24 h with or without acrolein (0-100 microM in L2 cells; 0-200 microM in lung slices). Treatment with this pneumotoxicant produced a concentration dependent decrease in intracellular ATP levels. Acrolein concentrations higher than 50 microM induced ATP decrease in slices, while this decrease occurred from 10 microM acrolein in L2 cells. Detoxification marker evaluations showed that mostly the glutathione pathway was altered after acrolein treatment in both models. Intracellular glutathione (GSH) levels were drastically increased with an acrolein concentration of 10 microM. This increase was concomitant with glutathione-S-transferase (GST) and glutathione reductase (GRED) activities in L2 cells. After this strong increase, these enzymatic activities as well as GSH levels were quickly decreased. In precision-cut rat lung slices, the induction of the glutathione pathway was less clear-cut. A bell-shaped dose response curve was observed with a maximum for 5 microM acrolein for GST and GRED activities. These differences between acrolein toxic ranges could be explained by the presence of an active detoxification pathway in slices compared to its relative lack in L2 cells.

Characterization of Precision-cut Rat Lung Slices in a Biphasic Gas/Liquid Exposure System: Effect of O(2).

Influence of oxygen on lung cell differentiation has been studied in precision-cut rat lung slice cultures. Rat lung slices were positioned on rolling inserts placed into vials with opened caps to allow free access to the gaseous phase. This system was placed into a continuous-flow rotating chamber with controlled pO(2), pCO(2) and hygrometry. Slices were cultured in a serum-free medium up to 3 days under an atmosphere of 21 or 70% oxygen. Cellular antioxidant markers demonstrated an oxygen concentration-dependent response. Slices cultured with 70% oxygen exhibited the highest specific activity of catalase, NADPH cytochrome c reductase and gamma-glutamyl transpeptidase (GGT) as well as the highest levels of intracellular glutathione after 48 or 72 hours of incubation. Moreover, hyperoxic exposure altered the expression of lung manganese-containing superoxide dismutase mRNA. Hyperoxia had little or no effect on intracellular ATP levels, which remained high in lung slices compared with freshly isolated tissue. The study of the pulmonary specific functions allowed to confirm maintenance of the in vitro cellular differentiation of lung slices incubated with 21% oxygen: (i) polyamine transport is preserved and exhibited kinetic properties similar to those observed in lung in vivo; (ii) ATP levels remained constant throughout the time course of incubation. This in vitro model proves to be a useful tool to study mechanisms involved after oxygen exposure and will probably be useful for the study of other environmental gaseous contaminants. Further developments in this method are under development.

Environment and human health.

The great French surgeon Leriche once said, "To be in good health is to live in the silence of one's organs." For Nature it is exactly the contrary, but one must not forget that the environment may strike in silence, as demonstrated by the accidents at Jintsu and Minamata in Japan. Close to 10 years were necessary to understand the mechanisms of deadly cadmium and mercury intoxications in humans. Two kinds of stresses to humans may come from the environment: (i) infectious disease, and (ii) unexpected, more-or-less complex chemical reactions.

Study of the interactions between copper, cadmium, and ferbam using the protozoan Colpidium campylum bioassay.

The toxicity of a copper-cadmium-ferbam mixture has been studied using the protozoan Colpidium campylum bioassay. The assays were designed according to the factorial experiments method, associated with multiple regression analysis. The results show that, at the concentrations tested, a synergy occurs between cadmium and ferbam, whereas the copper is only oligodynamic.

GC/MS confirmatory method for etorphine in horse urine.

A highly sensitive procedure for GC/MS determination of etorphine in horse urine is described. This assay provides both specificity and reliability and is particularly well suited for the confirmation of radioimmunoassay screening procedures usually used for etorphine. After solvent extraction and purifications, the etorphine is characterized as a pentafluoroacetic derivative (PFAA) by using mass fragmentography. The detection limit is 0.1 ng/mL in urine; the coefficient of variation of the estimations is 10.9%. The procedure has been validated after on-field administration of 5 to 90 micrograms of etorphine to five thoroughbred horses (10 to 180 ng/kg).

Low prevalence of byssinotic symptoms in 12 flax scutching mills in Normandy, France.

The concentrations of airborne dust and bacteria were determined in 12 flax scutching mills and in two milk processing plants in Normandy, France. A total of 308 of 340 flax workers and 111 of 113 milk processors volunteered to answer a respiratory questionnaire. Personal exposure to airborne dust in the scutching mills varied from 22.2 mg/m3 to 144 mg/m3 and areal concentrations from 8.92 mg/m3 to 47.1 mg/m3. The concentration of Gram negative bacteria ranged from 3970 (colony forming units) cfu/m3 to 67,900 cfu/m3 and that of total bacteria from 12,900 cfu/m3 to more than 600,000 cfu/m3. In all, 20% of the flax scutchers were found, on the basis of the questionnaire, to suffer from persistent cough and 25% from chronic phlegm production. The corresponding figures among milk processors were 3.6% and 4.5%. Unexpectedly, only 12.5% of the scutchers appeared to suffer from byssinotic symptoms even though they were heavily exposed to airborne dust and bacteria. The low prevalence of byssinosis might be due to self selection of the workforce or a relatively low concentration of the causative agent despite high airborne contamination.

An example of interaction between environmental pollutants: modification of thiram toxicity to freshwater organisms by nitrites or nitrates in relation to nitrosamine synthesis.

Thiram, a dithiocarbamate fungicide, is known to evolve to dimethylnitrosamine (DMNA) when associated with nitrites. Conditions of appearance of that carcinogenic compound have been studied in short-term experiments by association of the fungicide, nitrates or nitrites, and species representative of freshwater biota. DMNA has been estimated by GLC equipped with a specific detector. Chlorella vulgaris can rapidly produce nitrites from nitrates and DMNA is obtained in presence of thiram. Daphnia magna can also synthesize DMNA but nitrites have to be added to the medium. Increased toxicity of thiram is observed. The same results are obtained on Cyprinus carpio and for a part on Brachydanio rerio. When the species are associated in a 15-day experimental food chain, and intoxicated algae feed the two other levels, no significant transfer is observed. Nevertheless, some DMNA hazard may exist for particular species exposed to thiram associated with nitrites or even nitrates if algae are present.

[Study model of the mid-range ecotoxicity of chemical substances]. / Modèle d'étude de l'écotoxicité à moyen terme des substances chimiques.

Semi-chronic ecotoxic effects are measured by studying mortality and reproduction of daphnids, grown in toxic medium and fed with toxic chlorellae during 4 weeks. Toxic biosorption is controlled analytically. Toxicity of Cd++ at a concentration of an order of magnitude of by liter is revealed after 14 days. Cr6+ appears non toxic at concentrations under 25 micrograms/l.

Interest of dynamic tests in acute ecotoxicity assessment in algae.

Sorption of toxics by algae may be important and occurs very early. Thus, a decrease of the experimental toxic concentrations in the medium results in understating toxicity when tests are conducted under static conditions. In this work, two different methods of exposure of algae (Chlorella vulgaris) are studied, the static test and the pseudodynamic test. Acute effects (biological and analytical effects) of inorganic compounds (Cu2+, Cd2+, Pb2+, Cr6+) have been evaluated for 96 hr of exposure; in each case, IC50 is much lower in the dynamic condition than in the static one. The percentage of reduction varies from 55 to 75% after 96 hr. Accumulation of metal by chlorellae is greater when testing by the pseudodynamic way, with Cu2+ and Pb2+. But in the case of Cd2+ and Cr6+, the concentration factors are similar in the two kinds of exposure. These results point out the advantage of the pseudodynamic test, of which the methodology is very easy, for a more realistic assessment of acute ecotoxicity in these organisms.

Accumulation of cadmium in a freshwater food chain experimental model.

The study of food chain contamination in nature or in the laboratory requires precise definitions of some terms. A simplified model of a freshwater food chain has been elaborated to try to point out hazards related to the presence of cadmium in the aquatic environment. Three different species belonging to various trophic levels, but to the same aquatic systems were used. The required biological and analytical criteria are described. The time course of the experiment was 34 days starting with a 10-day contamination of the first trophic level (algae). The algae were then separated, washed with fresh medium, and given to the second trophic level (daphnids) to eat for 20 days. The third trophic level (fish) was then introduced for 4 days as a scavenger. The methodology was designed to determine the accumulation of cadmium by daphnids and then fish from the algal source. The results show a high direct bioaccumulation of cadmium in algae. The indirect bioaccumulation of daphnids was of the same order of magnitude, but for fish it was smaller. Nevertheless the cadmium transfer from daphnids to fish was obvious.

[Interest of some biological criteria in studying daphnids contaminated by cadmium nitrate (author's transl)]. / Utilisation de quelques critères d'études biologiques dans les intoxications à moyen terme de daphnies par du nitrate de cadmium.

Three biological criteria were studied on daphnids after 28 days of contamination with three different concentrations of cadmium (5, 10, 15 micrograms/l), such as mortality, dry weight and reproduction rate relative to general metabolic state of the crustacea. The value of Cl50-28 exceed 15 micrograms/l for dry weight and mortality determinations, on the other hand it is only 10 micrograms/l for reproduction rate. The latter appears as the most sensible criteria.

[Effect of pyrolysis products of polypropylene plastic on the defence mechanisms of the respiratory system (author's transl)]. / Effet du pyrolysat de matière plastique polypropylénique sur les mécanismes de défense de l'appareil respiratoire.

Since the use of plastic materials, a change in the pathology of fire victims has been observed. We studied the effects of a single short-term inhalation (30 min) of a sub-lethal dose of polypropylene pyrolysis products (one LD-0). Including control and test animals, 66 rats and 112 mice were used. The exposure provoked disturbances in the antixenic defense mechanisms of the respiratory system, chiefly in tracheo-bronchial defenses, since we observed a lowering of ciliary activity of 35 to 78% in test animals exposed a few hours before, compared with the controls. These changes provoked a significant increase in death-rate of test animals, following experimental airborne infection by Klebsiella pneumoniae. The combustion products of polypropylene plastic materials did not contain hydrocyanic acid nor hydrochloric acid, and neither the temperature of the inhaled air, nor the concentration of carbon monoxide could explain these effects. On the contrary, we can suspect the well known irritative properties of aldehyde compounds formed during smoldering combustion of polypropylene.

[Effect of ethanol, acetazolamide, and cyclophosphamide on protein and lecithin concentrations in broncho-alveolar liquid film of mice]. / Action de l'éthanol, l'acétazolamide et le cyclophosphamide sur les concentrations en protéines et lécithines du film liquidien broncho-alvéolaire de souris.

An original approach to reveal in Mice, the impact of some xenobiotics and drugs on the alveolo-capillary barrier...(ethanol, acetazolamide, cyclophosphamide is described. Drugs are injected I.P. during five days in subacute dose size. Concentrations of lecithines and proteins are settled in bronchoalveolar lavage fluids from animals having or not undergone an important blood loss just before the lavage.

[Acute inhalation toxicity of ammonia in rabbits]. / Toxicité aiguë par voie aérienne du gaz ammoniac chez le Lapin.

The aggressivity of ammonia at the pulmonary alveole level (intoxications in controlled ventilation) leads to an acute pulmonary oedema and cardio-vascular disfunctioning. Bradycardia is an early symptome (2,500 X 10(-6) but the real syndrome appears at 5,000 X 10(-6). Arterial pressure variations and blood gases modifications are significant, acidosis is systematic.