The present paper summarizes the data available in the literature concerning toxicity of the degradation products of 1,1,1,2-tetrahydrofluoroethane (HFC-134a), which is widely used worldwide as a refrigerant, and 2,3,3,3-tetrafluoropropene (HFO-1234yf), which is developed as a refrigerant for new generation. There are many studies available for toxic effects of carbon dioxide CO₂) and carbon monoxide (CO) in humans and animals. General toxicity of excessive CO₂ exposure in humans is well reported. However, information on reproductive and developmental toxicity of CO₂ in humans and animals is inadequate for risk assessment. As for CO, further studies are required to evaluate the adverse effects of chronic exposure to low and near ambient levels of CO on development of fetuses and newborn infants in marginal condition because of high susceptibility to hypoxic effect in fetuses and newborn infants. There is a lack of information on toxicity of trifluoroacetic acid, carbonyl fluoride, hydrogen fluoride, and formic acid in humans and animals. Animal studies remain necessary for risk assessment of chemicals because it is difficult to find alternative methods to determine the toxic effect of chemicals.

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Emerging nanotechnology has received great attention in recent years because of its widescale use in consumer products, healthcare, and medical applications, among others. Due to such rapid growth of nanomaterial manufacturing and use, these materials will inevitably be released into the environment. Currently little information exists on the fate and toxicological effects of nanoparticles in the environment including aquatic matrices. In this review, we discuss 1) possible ecological risks of silver nanomaterials as unbiodegradable and bioaccumulative contaminants, 2) environmental application of nanomaterials, 3) biological effects of nanomaterials to aquatic invertebrates and fishes, including biological fate and their indirect effects, 4) problems on nano-toxicity research, 5) regulatory science, and 6) nano-science and ecological risk. Here we highlight the need for further researches in order to understand the potential environmental/ecological hazard and risk of nanomaterials, with scientifically validated and environmentally relevant testing methods.

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Micronuclei (MN) and other nuclear abnormalities (NA) formation were confirmed in the peripheral erythrocytes of the red sea bream, Pagrus major, exposed to water- and diet-borne polycyclic aromatic hydrocarbons (PAHs). Their frequencies were significantly different from controls, with highest ∑MN&NA frequencies of 7.18 and 18.1 per 1000 erythrocytes in the water- and diet-borne exposures respectively, against highest water and dietary controls frequencies of 0.67 and 2.30 per 1000 erythrocytes respectively. ∑MN&NA persisted in the depuration period, and their frequencies varied directly with tissue ∑4PAH concentrations.
These biomarkers can be used in the red sea bream for PAH biomonitoring.

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Eleven organic compounds, including insecticides, herbicides, surfactants, and general organic compounds, and three metal ions were added to an aquatic model ecosystem (microcosm) comprising two photosynthetic organisms (Chlorella and Schizothrix), a protozoan (Cyclidium), two rotifers (Philodina and Lepadella), a worm (Aeolosoma), and at least 5 types of bacteria. The observed maximum concentrations of the substances having no effects on the respiration rate and the production rate in the microcosm at the mature stage (m-NOAECs) were determined. The m-NOAECs were compared with the predicted no-effect concentrations in the ecosystems (PNECs) that were estimated from the no-observed-effect concentrations of the substances in a single-species. There were significant differences in some of substances between the PNECs and the m-NOAECs. When the sensitivities to the substances were compared between the consumers and the producers, in the cases of the substances having higher sensitivity to the producers, the differences between the PNECs and the m-NOAECs were small; however, in the cases of the substances having higher sensitivity to the consumers, the PNECs were consistently lower than the m-NOAECs. The reason for the differences was discussed based on the calculated results using a mathematical model.

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To monitor monthly water quality in two Japanese rivers, we measured in situ hepatic and gill CYP1A activity in living see-through medaka by a method we had developed previously. The Sakura River is seasonally polluted by pesticides, and the Sakai River receives treated wastewaters from a waste disposal landfill site. Following exposure of the medaka for 24 h to water samples we determined hepatic and gill CYP1A activity by fluorescence microscopy. Exposure to river waters from both sites induced CYP1A activity in the liver and gills. This study confirms the practical usefulness of this method for monitoring environmental water quality.

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