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Cellulose nanofibril (CNF)-based materials are increasingly used in industrial and commercial applications. However, the impacts of CNF on aquatic life are poorly understood, and there are concerns regarding their potential toxicity. Using a combination of standard ecotoxicological tests and feeding experiments, we assessed the effects of CNF exposure (0.206-20.6 mg/L) on the feeding (food uptake and gut residence time) and life-history traits (growth and reproduction) in the cladoceran Daphnia magna. No mortality was observed in a 48 h acute exposure at 2060 mg/L. Moreover, a 21-day exposure at low food and moderate CNF levels induced a stimulatory effect on growth, likely driven by increased filtration efficiency, and, possibly, partial assimilation of the CNF by the animals. However, at low food levels and the highest CNF concentrations, growth and reproduction were negatively affected. These responses were linked to caloric restriction caused by dilution of the food source, but not an obstruction of the alimentary canal. Finally, no apparent translocation of CNF past the alimentary canal was detected. We conclude that CNF displays a low toxic potential to filter-feeding organisms and the expected environmental risks are low.

Sediments contaminated by human activities usually contain a mixture of chemicals that produce unforeseen combined toxic effects in organisms. Thus, traditional risk assessments based on the concen ...

Luning., K. G., Lake, S. and Linde, M. 1984. Genetics of inbred Drosophila melanogaster XII. Effects of an X-chromosome inversion on primary and secondary non-disjunction.—-Hereditas 100: 247–257. Lund, Sweden. ISSN 0018–0661. Received August 1, 1983 In an inbred line of Drosophila melanogaster. Oregon (code 2), an inversion covering the proximal half of the X-chromosome was induced (symbol: In(l) Lu-l y wd cxvf-2). It has been shown that inversion homozygotes have low frequencies of primary nun-disjunction. in the same manner as equilinear females with regular gene order of the 2–line. Intra-strain structural heterozygotes gave an excess of XO exceptionals but also a 5–fold increase of true primary non-disjunction (XXY) as compared to structural hornozygotes. Inter-strain crosses with mothers from line “K” revealed an influence both by the maternal genome and by the origin of the cytoplasm. Tests of secondary non-disjunction in structural heterozygous XXY females from both intra- and inter-strain crosses indicated highly complicated relations. When the mothers were of “2” origin the first brood showed lower frequencies of XXY exceptionals than in successive broods. whereas when the mother was of “K” origin there was a decrease after the 3rd brood (7th day). The “K”-line showed a dominance effect which was manifested by higher frequencies of XXY exceptionals. In regular daughters the Y-chromosome followed preferentially the proximal part of the X-chromosome of “K”. origin. There was no preference in the Y-chromosome distribution in intra-strain hybrids. There was a pronounced low frequency of recombinants among exceptionals. This indicates that the high frequencies of exceptionals from inversion heterozygous XXY females occur by another mechanism than in equilinear XXY females with the same genetic background.

The toxicity of nine effluents from Swedish kraft-pulp mills using conventional, elemental chlorine-free (ECF) and totally chlorine-free (TCF) bleaching processes was studied. Effluents represented six different processes: conventional-softwood 30% ClO2; ECF-softwood; TCF-hardwood, for which all the samples were taken before and after secondary treatment; conventional-softwood 8% ClO2; TCF-softwood O3/H2O2; and TCF-softwood H2O2. Comparison of effluents, which had not undergone secondary treatment, suggested that those from mills using conventional bleached pulp were the most toxic, with toxic emission factors (TEF) ≈ 1,000 according to the Microtox® test (AZUR Environmental, Carlsbad, CA, USA). In the acute Nitocra spinipes test, the conventional-softwood 8% ClO2 and the ECF-softwood effluents before secondary treatment were the most toxic, with TEF ≈ 700. In the reproduction test, N. spinipes was two to three times more sensitive than in the lethal test. The species most sensitive to the effluents investigated was the macroalga Ceramium strictum, with TEF values up to 3,000. The conventional effluent using a substitution of 8% ClO2 was the most toxic, and the TCF effluents were the least toxic. Degradation treatment of the ECF and TCF effluents for 28 d in the laboratory did not eliminate acute lethal effects on N. spinipes and the Microtox bacterium.

Ash from incinerated waste consists mainly of a complex mixture of metals and other inorganic elements and should be classified based on its inherent hazardous effects according to EUs Waste Framework Directive. In a previous study, we classified eight eluates from ash materials from Swedish incineration plants, both chemically and ecotoxicologically (using bacteria, algae, crustacean and fish). Based on measured concentrations in the eluates together with literature acute toxicity data on the crustacean Nitocra spinipes we identified six elements (i.e. Zn, Cu, Pb, Al, K and Ca) potentially responsible for the observed ecotoxicity. However, comparing the used test methods with N. spinipes, the acute test was relatively insensitive to the eluates, whereas the (sub)chronic test (i.e. a partial life cycle test, investigating larval development ratio) was very sensitive. The overall aim of this follow-up study was to verify if the pinpointed elements could be responsible for the observed (sub)chronic toxicity of the eluates. Individual effect levels (i.e. NOEC values) for these six elements were therefore generated using the (sub)chronic test. Our results show that for six of the eight eluates, the observed ecotoxicity can be explained by individual elements not classified as ecotoxic (Al, K and Ca) according to chemical legislation. These elements will not be considered using summation models on elements classified as ecotoxic in solid material for the classification of H-14, but will have significant implications using ecotoxicological test methods for this purpose.

The carbonic anhydrase isozymes (CA I and CA II) of the pig-tailed macaque, Macaca nemestrina , have been chosen to study the regulation of enzyme levels in red blood cells. Two quantitative variants of CA I that are ideal for studies of enzyme regulation exist in this species. One variant is one of four known electrophoretic types of CA I, designated CA Ia, which is present at levels about 30% of those of the other electrophoretic types. The other is a deficiency variant of CA I which, in homozygotes, reduces the product of the CA I locus about 5000-fold and reduces the product of the CA II locus by about 60%. l -[ 14 C]Serine was used to study the biosynthesis of CA I and CA II isozymes in the reticulocytes of animals carrying these CA I variants. Specific radioactivity and total incorporation data from bone marrow erythroid cells, and peripheral blood reticulocytes indicate that the reduced CA Ia concentration is probably the result of degradation. This degradation appears to occur for only a short time before the reticulocytes enter the peripheral blood. It was not possible to determine whether the 5000-fold reduction of CA I in the CA I-deficient animals is due to reduced transcription, reduced translation, or degradation. The effect of the CA I-deficiency mutation on the synthesis of CA II was also studied. For each dose of CA I-deficiency gene, there appears to be a 30% reduction in the rate of l -[ 14 C]serine incorporation into CA II, thereby accounting for the reduced CA II concentration in CA I-deficient animals.