NOEC Values Research Articles

Spawning and multiple end points of the embryo-larval bioassay of the blue mussel Mytilus galloprovincialis (Lmk).

Since the 1960s, little has been done to improve and simulate the use of short-duration chronic bioassays of bivalve embryos, particularly in mussels. However, these test organisms offer great advantages in relation to other groups, due to the ease of obtaining breeders in cultivation systems, in the environment and any time, and due to their high sensitivity to chemicals or contaminants. To contribute some methodological aspects, this study uses techniques to stimulate spawning or improve the obtaining of gametes for use in bioassays with the mussel Mytilus galloprovincialis. It also evaluates different criteria for determining the effect on the larvae, for estimation of EC50 and NOEC values, based on morphological analysis of developmental delay and the biometrics of the larvae. KCl proved to be a reliable inducer of spawning, with positive responses in 10 of the 12 months of the year tested. Moreover, this chemical, in association with NH4Cl, demonstrated the capacity to activate immature oocytes obtained from extirpated gonads, enabling an improvement in fertilization rates. The different criteria adopted to determine the effects on the larvae in the assays with reference toxicants (SDS and K2Cr2O7) resulted in EC50 and NOEC values without significant differences, indicating reliability in the results and freedom in the choice of criteria of effect to be adopted in the trials.

Toxic effects of chemical dispersant Corexit 9500 on water flea Daphnia magna.

In 2010, approximately 2.1 million gallons of chemical dispersants, mainly Corexit 9500, were applied in the Gulf of Mexico to prevent the oil slick from reaching shorelines and to accelerate biodegradation of oil during the Deepwater Horizon oil spill. Recent studies have revealed toxic effects of Corexit 9500 on marine microzooplankton that play important roles in food chains in marine ecosystems. However, there is still little known about the toxic effects of Corexit 9500 on freshwater zooplankton, even though oil spills do occur in freshwater and chemical dispersants may be used in response to these spills. The cladoceran crustacean, water flea Daphnia magna, is a well-established model species for various toxicological tests, including detection of juvenile hormone-like activity in test compounds. In this study, we conducted laboratory experiments to investigate the acute and chronic toxicity of Corexit 9500 using D. magna. The acute toxicity test was conducted according to OECD TG202 and the 48 h EC50 was 1.31 ppm (CIs 0.99-1.64 ppm). The reproductive chronic toxicity test was performed following OECD TG211 ANNEX 7 and 21 days LOEC and NOEC values were 4.0 and 2.0 ppm, respectively. These results indicate that Corexit 9500 has toxic effects on daphnids, particularly during the neonatal developmental stage, which is consistent with marine zooplankton results, whereas juvenile hormone-like activity was not identified. Therefore, our findings of the adverse effects of Corexit 9500 on daphnids suggest that application of this type of chemical dispersant may have catastrophic impacts on freshwater ecosystems by disrupting the key food chain network. Copyright © 2016 John Wiley & Sons, Ltd.

Inhalation TTC values: A new integrative grouping approach considering structural, toxicological and mechanistic features

The present publication describes an integrative grouping concept to derive threshold values for inhalation exposure. The classification scheme starts with differences in toxicological potency and develops criteria to group compounds into two potency classes, namely toxic (T-group) or low toxic (L-group).The TTC concept for inhalation exposure is based on the TTC RepDose data set, consisting of 296 organic compounds with 608 repeated-dose inhalation studies. Initially, 21 structural features (SFs) were identified as being characteristic for compounds of either high or low NOEC values (Schüürmann et al., 2016). In subsequent analyses these SF groups were further refined by taking into account structural homogeneity, type of toxicological effect observed, differences in absorption, metabolism and mechanism of action (MoA), to better define their structural and toxicological boundaries. Differentiation of a local or systemic mode of action did not improve the classification scheme.Finally, 28 groups were discriminated: 19 T-groups and 9 L-groups. Clearly distinct thresholds were derived for the T- and L-toxicity groups, being 2 × 10−5 ppm (2 μg/person/day) and 0.05 ppm (4260 μg/person/day), respectively. The derived thresholds and the classification are compared to the initial mainly structure driven grouping (Schüürmann et al., 2016) and to the Cramer classification.

Lethal and sub-lethal effects of five pesticides used in rice farming on the earthworm Eisenia fetida

The toxicity of five pesticides typically used in rice farming (trichlorfon, dimethoate, carbendazim, tebuconazole and prochloraz) was evaluated on different lethal and sub-lethal endpoints of the earthworm Eisenia fetida. The evaluated endpoints included: avoidance behaviour after an exposure period of 2 days; and mortality, weight loss, enzymatic activities (cholinesterase, lactate dehydrogenase and alkaline phosphatase) and histopathological effects after an exposure period of 14 days. Carbendazim was found to be highly toxic to E. fetida (LC50=2mg/kg d.w.), significantly reducing earthworm weight and showing an avoidance response at soil concentrations that are close to those predicted in rice-fields and in surrounding ecosystems. The insecticide dimethoate showed a moderate acute toxicity (LC50=28mg/kg d.w.), whereas the rest of tested pesticides showed low toxicity potential (LC50 values above 100mg/kg d.w.). For these pesticides, however, weight loss was identified as a sensitive endpoint, with NOEC values approximately 2 times or lower than the calculated LC10 values. The investigated effects on the enzymatic activities of E. fetida and the observed histopathological alterations (longitudinal and circular muscle lesions, edematous tissues, endothelial degeneration and necrosis) proved to be sensitive biomarkers to monitor pesticide contamination and are proposed as alternative measures to evaluate pesticide risks on agro-ecosystems.

Genotoxic and cytotoxic effects of ZnO nanoparticles for Dunaliella tertiolecta and comparison with SiO2 and TiO2 effects at population growth inhibition levels

The increasing use of oxide nanoparticles (NPs) in commercial products has intensified the potential release into the aquatic environment where algae represent the basis of the trophic chain. NP effects upon algae population growth were indeed already reported in literature, but the concurrent effects at cellular and genomic levels are still largely unexplored.Our work investigates the genotoxic (by COMET assay) and cytotoxic effects (by qualitative ROS production and cell viability) of ZnO nanoparticles toward marine microalgae Dunaliella tertiolecta. A comparison at defined population growth inhibition levels (i.e. 50% Effect Concentration, EC50, and No Observed Effect Concentration, NOEC) with SiO2 and TiO2 genotoxic effects and previously investigated cytotoxic effects (Manzo et al., 2015) was performed in order to elucidate the possible diverse mechanisms leading to algae growth inhibition.After 72h exposure, ZnO particles act firstly at the level of cell division inhibition (EC50: 2mg Zn/L) while the genotoxic action is evident only starting from 5mg Zn/L. This outcome could be ascribable mainly to the release of toxic ions from the aggregate of ZnO particle in the proximity of cell membrane.In the main, at EC50 and NOEC values for ZnO NPs showed the lowest cytotoxic and genotoxic effect with respect to TiO2 and SiO2. Based on Mutagenic Index (MI) the rank of toxicity is actually: TiO2>SiO2>ZnO with TiO2 and SiO2 that showed similar MI values at both NOEC and EC50 concentrations.The results presented herein suggest that up to TiO2 NOEC (7.5mg/L), the algae DNA repair mechanism is efficient and the DNA damage does not result in an evident algae population growth inhibition. A similar trend for SiO2, although at lower effect level with respect to TiO2, is observable.The comparison among all the tested nanomaterial toxicity patterns highlighted that the algae population growth inhibition occurred through pathways specific for each NP also related to their different physicochemical behaviors in seawater.

Review of the Ecotoxicological Properties of the Methylenedianiline Substances.

Concerning chronic toxicity, D. magna is the most sensitive species tested against MDA aquatic exposures, with a 21days-NOEC of 0.00525mg/L. Exposure of daphnids takes place via the aquatic phase. Other species of the same phylum (Arthropoda) appear to be less sensitive albeit with exposures via soil or sediment, with a 28days-NOEC of 562mg/kg d. w. soil (F. candida) and 41.3mg/kg d. w. sediment (Hyalella azteca), for reproductive and survival endpoints, respectively. Also for acute toxicity, D. magna is more sensitive than the other species, with an 48h-EC50 that spreads over two orders of magnitude, ranging from 0.019 to 2.7mg/L. Fish show a more uniform reaction to MDA, with 96h-LC50 ranging from about 20 to 60mg/L; chronic data for fish are not available. Acute toxicity data for algae and cyanobacteria are in the range of 1-10mg/L; based on growth rate, the 72h-NOECr or ErC10 of MDA to algae is 0.3-9.3mg/L.For sediment organisms, the black worm L. variegatus shows the highest sensitivity against MDA with a NOEC between ≤3.75mg/kg and 30mg/kgd. w., followed by the amphipod H. azteca. The lower sensitivity of L. variegatus in the second study compared to the first study is obviously attributable to the different feeding regimes (semi-continuous feeding against pre-spiked sediment). One argument might be that semi-continuous feeding allows the organisms to avoid the contaminated food. However, a change from semi-continuous feeding to sediment pre-spiked with nettle powder (Urtica sp.) results in an earlier and much stronger increase in ammonia concentration in the system. This became apparent after both studies on the blackworm were finalized. The ammonia 96h-EC50 for the blackworm is 0.69mg/L at pH = 8.2, and the 96h-EC10 at pH = 8.2 is 0.33mg/L (Hickey and Vickers, Arch Environ Contam Toxicol 26:292-298, 1994). As a result, the lower NOEC and LOEC in the second study with L. variegatus are probably attributable to interference by ammonia.MDA binds irreversibly to soil and sediment which may explain the general, but not uniform lower sensitivity of soil and sediment organisms against aquatic organisms. However, species with intense soil or sediment contact (L. variegatus and E. fetida) show in general lower NOEC values than those organisms with less direct contact (3.75 and 11.2mg/kg d. w., respectively). On the one hand it may be hypothesized that this intense contact to soil bound MDA is one reason for the higher sensitivity; on the other hand, metabolic capacity against MDA of the organisms tested is unknown at this point in time and might as well explain differences in species sensitivity. For plants there are only acute data available, and in respect to acute toxicity L. sativa is more sensitive to MDA than E. fetida.Limited aquatic data available so far do not indicate that the toxicity of pMDA is different to MDA. In addition, the limited set of data generated with the marine M. macrocopa (crustacean), N. fustulum (diatom) and V. fisheri (bacteria) do not indicate that sea water organisms are more sensitive to MDA than fresh water organisms.In mammals, MDA is unlikely to interact with the endocrine sexual system; interaction with the adrenergic system cannot be ruled out, and effects of MDA on the thyroid hormone system have been demonstrated. MDA inhibits the thyroid peroxidase which might contribute to the thyroid gland tumors observed in chronic studies with rats and mice. Some anti-androgenic activity in in vitro studies with yeast cell did not prevail in in vivo studies with rats and mice.

Outcome of the pesticides peer review meeting on general recurring issues in ecotoxicology

Outcome of the pesticides peer review meeting on general recurring issues in ecotoxicology

Comparison of NOEC values to EC10/EC20 values, including confidence intervals, in aquatic and terrestrial ecotoxicological risk assessment

Comparison of NOEC values to EC10/EC20 values, including confidence intervals, in aquatic and terrestrial ecotoxicological risk assessment

Isomerization Of Ethylhexyl Methoxycinnamate In Cosmetics Can Lead To Higher Probabilistic Risks

Ethylhexyl methoxycinnamate (EHMC, CAS: 5466-77-3) is one of the most widespread UV filter used in sunscreens to protect human skin from the harmful effects of UV radiation and also as the UV absorber to prevent light-induced product degradation in many personal care products (PCPs). EHMC occurs in normal condition as trans isomer, which isomerizes during sunlight exposure to the cis-EHMC. There is evidence about adverse toxicological effects of the trans-EHMC, while the data on the toxicity of the cis-EHMC are missing. The aim of this study was to fill the data gaps about the genotoxicity of the cis-EHMC and to compare genotoxicity response of both isomers. Using experimental data, we quantified human risks focusing on the female population, which can be exposed to higher concentration of trans/cis-EHMC via dermal route, inhalation or ingestion due to major use of PCPs. UmuC test on bacterial strain Salmonella Typhimurium was used for genotoxicity evaluation of trans- and cis-EHMC. The NOEC of both isomers, calculated and extrapolated according to Qivive approach (quantitative in vitro-to-in vivo extrapolation), was used for screening probabilistic human risk assessment. The aggregate exposure distributions for trans/cis-EHMC were generated using Monte Carlo Simulations. In our study we measured genotoxic potential of both EHMC isomers to compare their genotoxicity response. The obtained NOEC values based on the experimental data: NOECtrans-EHMC = 0.064 mg ml-1 and NOECcis-EHMC = 0.038 mg ml-1 were used in probabilistic risk prediction, where cis-EHMC showed risk 1.7 times higher than trans-EHMC. Sun exposure after application of PCPs containing EHMC can lead to a much higher risk for whole population. This study brings new data on the toxicity of cis-EHMC that until now wasn't assessed. Our results showed that, due to the isomerization, the exposure to EHMC in PCPs can result in higher health risks than expected. EHMC application requires detailed reassessment.

Contribution for the derivation of a soil screening value (SSV) for uranium, using a natural reference soil.

In order to regulate the management of contaminated land, many countries have been deriving soil screening values (SSV). However, the ecotoxicological data available for uranium is still insufficient and incapable to generate SSVs for European soils. In this sense, and so as to make up for this shortcoming, a battery of ecotoxicological assays focusing on soil functions and organisms, and a wide range of endpoints was carried out, using a natural soil artificially spiked with uranium. In terrestrial ecotoxicology, it is widely recognized that soils have different properties that can influence the bioavailability and the toxicity of chemicals. In this context, SSVs derived for artificial soils or for other types of natural soils, may lead to unfeasible environmental risk assessment. Hence, the use of natural regional representative soils is of great importance in the derivation of SSVs. A Portuguese natural reference soil PTRS1, from a granitic region, was thereby applied as test substrate. This study allowed the determination of NOEC, LOEC, EC20 and EC50 values for uranium. Dehydrogenase and urease enzymes displayed the lowest values (34.9 and <134.5 mg U Kg, respectively). Eisenia andrei and Enchytraeus crypticus revealed to be more sensitive to uranium than Folsomia candida. EC50 values of 631.00, 518.65 and 851.64 mg U Kg were recorded for the three species, respectively. Concerning plants, only Lactuca sativa was affected by U at concentrations up to 1000 mg U kg1. The outcomes of the study may in part be constrained by physical and chemical characteristics of soils, hence contributing to the discrepancy between the toxicity data generated in this study and that available in the literature. Following the assessment factor method, a predicted no effect concentration (PNEC) value of 15.5 mg kg−1 dw was obtained for U. This PNEC value is proposed as a SSV for soils similar to the PTRS1.

Ecotoxicity and Environmental Risk Assessment of Larvicides Used in the Control of Aedes aegypti to Daphnia magna (Crustacea, Cladocera)

Dengue transmitted by mosquitoes of the genus Aedes, species aegypti, is a major public health concern in Brazil. The chemical control of the mosquito larvae has been performed with the larvicide temephos since 1967. However, vector resistance was reported to temephos in several Brazilian states, and the Ministry of Health ordered the replacement of this larvicide by diflubenzuron (DFB), an inhibitor of chitin synthesis. Both insecticides are diluted in water with larvae and are able to reach aquatic environments in which they subsequently adversely damage nontarget organisms. The aims of this study were to (1) determine the acute toxicity (EC50) and environmental risk (RQ) of DFB and temephos to the microcrustacean Daphnia magna, and (2) evaluate the chronic toxicity (no-observed-effect concentration [NOEC] and lowest-observed-effect concentration [LOEC]) of these larvicides to D. magna. The experiments were performed according to a completely randomized design. The estimated 48-h EC50 of temephos was 0.15 μg/L (lower limit = 0.1 and upper limit = 0.2 μg/L) and the 48-h EC50 of DFB was 0.06 μg/L (lower limit = 0.03 and upper limit = 0.1 μg/L). RQ values were 4.166.7 to DFB and 6.666.6 to temephos. NOEC and LOEC values were respectively 2.5 and 5 ng/L for DFB, and respectively 6.2 and 12.5 ng/L for temephos. Thus, temephos and DFB are classified as highly toxic to Daphnia magna and pose a high environmental risk to this species. Mortality of D. magna was observed at concentrations lower than those used in the field to control A. aegypti larvae.

Preliminary aquatic risk assessment of imidacloprid after application in an experimental rice plot

The potential aquatic risk of application of the neonicotinoid insecticide imidacloprid for aphid control in rice was assessed. To this end, imidacloprid was applied as Confidor® 200 SC at the recommended field dose of 100g a.i./ha to a Portuguese rice plot. Subsequently, fate of the test compound in water and potential effects of water samples on a battery of test species were determined. As compared to the first-tier predicted environmental concentrations (PECs) calculated using MED-Rice (around 30µg/L depending on the scenario used) and US-EPA (78µg/L) simulations, the actual peak concentration measured in the paddy water (52µg/L) was higher and lower, respectively. As was anticipated based on 50% effect concentrations (EC50 values) for Daphnia magna published in the open literature and that calculated in the present study (48h-EC50 immobility=84mg/L), no effects were observed of field water samples on daphnids. The sediment-dwelling ostracod Heterocypris incongruens, however, appeared relatively sensitive towards imidacloprid (6d-EC50 growth inhibition=0.01–0.015mg/L) and a slight effect was indeed noted in field samples taken the first week after application. Species sensitivity distributions based on published EC50 and NOEC values also revealed that other species are likely to be affected at the peak and time-weighted average imidacloprid concentrations, respectively. By applying the relative tolerance approach (i.e. by dividing the EC50 value of a certain species with that of Daphnia magna), ostracods appear to contain the most sensitive taxa to imidacloprid, followed by EPT (Ephemeroptera, Plecoptera and Trichoptera) taxa. Future field studies into (higher-tier) fate modelling of pesticides in rice paddies and effect assessment on field communities are required to ensure protection of aquatic life and wildlife (e.g. birds) from pesticide stress.

Improved understanding of key elements governing the toxicity of energy ash eluates

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.

Influence of existing site contamination on sensitivity of Rhinella fernandezae (Anura, Bufonidae) tadpoles to Lorsban®48E formulation of chlorpyrifos

Effects of the widely employed insecticide Lorsban(®)48E formulation of chlorpyrifos (CPF) was studied on Rhinella fernandezae tadpoles, a native species of Argentina, Brazil, Paraguay and Uruguay, under the hypothesis of a differential response of organisms from ponds of two sites with different degree of anthropogenic disturbance: S1 an unpolluted area, and S2 area with high degree of antropogenic disturbance. To collect a representative sample of the genotypic variability of each population, small portions from six clutches were taken randomly from each site when the period of clutching was finished. Embryos and tadpoles were maintained under controlled laboratory conditions. Toxicity tests were conducted under standardized conditions to study acute and chronic lethal (mortality) and sublethal effects (behavior, growth, and abnormalities), within the range of concentrations of 0.010 to 5 mg/L. Chronic effects were assessed with organisms from one of the demes (S1). CPF showed high toxicity on the tadpoles, inducing lethal and sublethal effects at 96 h exposure within a narrow range of concentrations from 0.066 to 0.887 mg/L. Results indicate that R. fernandezae tadpoles are below the 30th percentile in the species sensitivity distribution of existing data. The acute LC50, NOEC, and LOEC values were 0.151, 0.066, and 0.133 mg/L for S1, and 0.293, 0.177, and 0.266 mg/L for S2, respectively. Considering all acute end-points evaluated, the effects of CPF showed no significant differences (p = 0.3484) between the studied populations. CPF has more severe effects at higher concentrations than at higher times of exposure. Contaminants in S2 do not seem to induce local adaptation. Sublethal effects data and measured environmental concentrations indicate potential risk for populations inhabiting agroecosystems.

P-glycoprotein (P-gp) in the monogonont rotifer, Brachionus koreanus: Molecular characterization and expression in response to pharmaceuticals

P-glycoprotein is involved in the efflux of diverse chemicals, including hydrophobic compounds and pharmaceuticals as a first line of defense. Here, we firstly identified and characterized the P-gp (Bk-P-gp) gene in the rotifer, Brachionus koreanus. Bk-P-gp was highly conserved in genomic organization compared to the human P-gp gene. Messenger RNA expression of Bk-P-gp revealed that it would be regulated by temperature change via 14 heat shock response elements in its promoter region. Bk-P-gp showed a high similarity of motifs/domains compared to those of vertebrates in its amino acid sequences. To check whether Bk-P-gp would be inducible, we exposed B. koreanus to six pharmaceuticals including antibiotics for use in aquaculture and observed dose- and time-dependency on transcripts of Bk-P-gp for 24h over a wide range of concentration. Efflux assay and membrane topology supported its conserved function for transportation of a number of chemicals upon cellular damage. To reveal the effect of pharmaceuticals on the rotifer, we measured survival rate and population growth rate after exposure to six pharmaceuticals. In an acute toxicity test, both NOEC and LC50 values for all the pharmaceuticals were high for 24h. ATP, CBZ, SMX, and TMP markedly inhibited the population growth of B. koreanus after exposure up to 100mg/L for 10 days. In this paper, we demonstrated that various pharmaceuticals can retard growth rate with up-regulation of the P-gp gene as a cellular defense system. This finding provides a better understanding of molecular mechanisms involved in pharmaceutical-mediated cellular damage in B. koreanus.

Lignin and tannin toxicity to Phaeodactylum tricornutum (Bohlin)

Lignin and tannin are widespread natural compounds traditionally used in tannery industries. Their presence is commonly detected in textile wastewater showing potential toxicity effects within various endpoints onto sea water organisms that generally represent the ultimate target of discharged effluents. Most data are available only as nominal concentrations or percentage volume of wastewater having an unknown lignin and tannin content. The aim of this study was to provide the ecotoxicological characterisation of both compounds considering as testing species the marine alga Phaeodactylum tricornutum (Bohlin). Lignin and tannin showed an E rC 50 of 113.84 (100.90–128.45) mg/L and 26.04 (20.10–33.95) mg/L, respectively. NOEC and LOEC values were together <0.1 mg/L and 0.1 mg/L, in that order. Moreover, it was observed a morphological change of the algae fusiform shape occurring only at tannin concentrations ≥75 mg/L and <185 mg/L.

Stage‐dependent toxicity of 2,4‐dichlorophenoxyacetic on the embryonic development of a South American toad, Rhinella arenarum

The acute and short term chronic toxicity of both the herbicide butyl ester of 2,4-Dichlorophenoxyacetic acid (2,4-D) and a commercial formulation (CF) were evaluated on Rhinella (= Bufo) arenarum embryos at different developmental stages. Adverse effects were analyzed by means of the isotoxicity curves for lethality, malformations, stage-dependent susceptibility, and ultrastructural features. For all experimental conditions, the CF was more toxic, up to 10 times, than the active ingredient, being the open mouth stage (S.21) the most susceptible to the herbicide. For continuous treatment conditions, the early embryonic development was the most susceptible to 2,4-D and the LC50s for 96 and 168 h were 9.06 and 7.76 mg L(-1) respectively. In addition, both the active ingredient and the CF were highly teratogenic, resulting in reduced body size, delayed development, microcephaly, agenesis of gills, and abnormal cellular proliferation processes as the main adverse effects. According to US EPA, 2,4-D in agricultural scenarios may be up to three times higher than the NOEC values for teratogenic effects reported in this study. Therefore, they might represent a risk for amphibians. This study also points out the relevance of reporting the susceptibility of embryos at different developmental stages to both the active ingredient and the CF of agrochemicals in order to protect nontarget organisms.

Comparative toxicity of antifouling compounds on the development of sea urchin

In the present study, embryotoxicity experiments using the sea urchin Lytechinus variegatus were carried out to better clarify the ecotoxicological effects of tributyltin (TBT) and triphenyltin (TPT) (the recently banned antifouling agents), and Irgarol and Diuron (two of the new commonly used booster biocides). Organisms were individually examined to evaluate the intensity and type of effects on embryo-larval development, this procedure has not been commonly used, however it showed to be a potentially suitable approach for toxicity assessment. NOEC and LOEC were similar for compounds of same chemical class, and IC10 values were very close and showed overlapping of confidence intervals between TBT and TPT, and between Diuron and Irgarol. In addition, IC10 were similar to NOEC values. Regardless of this, the observed effects were different. Embryo development was interrupted at the gastrula and blastula stages at 1.25 and 2.5 μg l(-1) of TBT, respectively, whereas pluteus stage was reached with the corresponding concentrations of TPT. Furthermore, embryos reached the prism and morula stages at 5 μg l(-1) of TPT and TBT, respectively. The effects induced by Irgarol were also more pronounced than those caused by Diuron. Pluteus stage was always reached at any tested Diuron concentration, while embryogenesis was interrupted at blastula/gastrula stages at the highest concentrations of Irgarol. Therefore, this study proposes a complementary approach for interpreting embryo-larval responses that may be employed together with the traditional way of analysis. Consequently, this application leads to a more powerful ecotoxicological assessment tool focused on embryotoxicity.

Toxicity Testing of Waterborne Mercury with Red Sea Bream (Pagrus major) Embryos and Larvae

Acute toxicity tests revealed that, in red sea bream (Pagrus major) embryos, 24 and 48h LC(50) values of waterborne HgCl(2) were 67.3 and 39.1μg Hg(2+) L(-1). In larvae, 48, 72 and 96h LC(50) values were 41.9, 36.1 and 34.8μg Hg(2+) L(-1), respectively. Sub-chronic toxicity tests indicated that mercury concentrations ≥20μg Hg(2+) L(-1) decreased hatching success, increased mortality and induced teratogenicity in embryos and larvae. The NOEC, LOEC and MATC values were 8.0, 16.3 and 11.4μg Hg(2+) L(-1) for hatching success, mortality and teratogenicity; while those were 27.0, 36.9 and 31.6μg Hg(2+) L(-1) for body length and specific growth rate, respectively.

Health and environmental safety aspects of friction grinding and spray drying of microfibrillated cellulose

Microfibrillated cellulose (MFC), also referred to as nanocellulose, is one of the most promising innovations for forest sector. MFC is produced by fibrillating the fibres under high compression and shear forces. In this study we evaluated the worker exposures to particles in air during grinding and spray drying of birch cellulose. Processing of MFC with either a friction grinder or a spray dryer did not cause significant exposure to particles during normal operation. Grinding generated small amount of particles, which were mostly removed by fume hood. Spray dryer leaked particles when duct valve was closed, but when correctly operated the exposure to particles was low or nonexistent. To assess the health effects of the produced MFC, mouse macrophages and human monocyte derived macrophages were exposed to MFC and the viability and cytokine profile of the cells were studied thereafter. No evidence of inflammatory effects or cytotoxicity on mouse and human macrophages was observed after 6 and 24 h exposure to the materials studied. The results of toxicity studies suggest that the friction ground MFC is not cytotoxic and does not cause any effects on inflammatory system in macrophages. In addition, environmental safety of MFC was studied with ecotoxicity test. Acute environmental toxicity assessed with kinetic luminescent bacteria test showed high NOEC values (>100 mg/l) for studied MFC. However, MFC disturbed Daphnia magna mobility mechanically when the test was performed according to the standard procedure.