Predictions of Toxicity to Chlorella vulgaris and the Use of Momentum-space Descriptors

The toxicity to Chlorella vulgaris, expressed as log(1/EC50), of two sets of aromatic compounds has been examined. For the first set, which consists of 13 mono- and di-substituted nitrobenzenes, it was found that one- or two-descriptor models provide useful correlations. A six-descriptor regression model for the log(1/EC50) values of a larger set that consists of 49 aromatic compounds has also been developed. Overall, it was found that a combination of a small number of trivial ‘feature count’ classical descriptors (numbers of atoms of a particular type) and less traditional quantities (entropy-like momentum-space descriptors) have potential benefits for useful QSAR models

Review of Data Sources, QSARs and Integrated Testing Strategies for Aquatic Toxicity

This review collects information on sources of aquatic toxicity data and computational tools for estimation of chemical toxicity aquatic to aquatic organisms, such as expert systems and quantitative structure-activity relationship (QSAR) models. The review also captures current thinking of what constitutes an integrated testing strategy (ITS) for this endpoint. The emphasis of the review is on the usefulness of the models and for the regulatory assessment of chemicals, particularly for the purposes of the new European legislation for the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), which entered into force on 1 June 2007. Effects on organisms from three trophic levels (fish, Daphnia and algae) were subject of this review. In addition to traditional data sources such as databases, papers publishing experimental data are also identified. Models for narcoses, general (global) models as well as models for specific chemical classes and mechanisms of action are summarised. Where possible, models were included in a form allowing reproduction without consultation with the original paper. This review builds on work carried out in the framework of the REACH Implementation Projects, and was prepared as a contribution to the EU funded Integrated Project, OSIRIS.JRC.I.3-Toxicology and chemical substance

Low potency toxins reveal dense interaction networks in metabolism

Background The chemicals of metabolism are constructed of a small set of atoms and bonds. This may be because chemical structures outside the chemical space in which life operates are incompatible with biochemistry, or because mechanisms to make or utilize such excluded structures has not evolved. In this paper I address the extent to which biochemistry is restricted to a small fraction of the chemical space of possible chemicals, a restricted subset that I call Biochemical Space. I explore evidence that this restriction is at least in part due to selection again specific structures, and suggest a mechanism by which this occurs. Results Chemicals that contain structures that our outside Biochemical Space (UnBiological groups) are more likely to be toxic to a wide range of organisms, even though they have no specifically toxic groups and no obvious mechanism of toxicity. This correlation of UnBiological with toxicity is stronger for low potency (millimolar) toxins. I relate this to the observation that most chemicals interact with many biological structures at low millimolar toxicity. I hypothesise that life has to select its components not only to have a specific set of functions but also to avoid interactions with all the other components of life that might degrade their function. Conclusions The chemistry of life has to form a dense, self-consistent network of chemical structures, and cannot easily be arbitrarily extended. The toxicity of arbitrary chemicals is a reflection of the disruption to that network occasioned by trying to insert a chemical into it without also selecting all the other components to tolerate that chemical. This suggests new ways to test for the toxicity of chemicals, and that engineering organisms to make high concentrations of materials such as chemical precursors or fuels may require more substantial engineering than just of the synthetic pathways involved

Ecotoxicologial assessment of cetylpyridinium chloride and 1-(2-hydroxyethyl)-3-methylimidazolium chloride

Ionic liquids (ILs) are salts that are stable over their melting temperature and are made exclusively of ions (one organic cation and one organic or inorganic anion). This chemical class has received considerable interest due to their unique and tuneable properties. The growing interest in ILs predicts an increase of their manufacture and use at industrial scale, which may result in the increased release of these compounds into the environment. In the past years, ILs have been used as a greener alternative to hazardous conventional solvents, although few data regarding the toxicity and ecotoxicity of ILs is available. In the present work, we assessed the ecotoxicological profile of one imidazolium based IL, 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([C2OHMIM][Cl]), and one pyridinium based IL, cetylpyridinium chloride ([C16Pyr][Cl]). The ecotoxicological evaluation was performed using a battery of test organisms from different ecosystems and from different trophic levels: Chlorella vulgaris, Daphnia magna, Artemia salina, Lactuca sativa and Allium cepa. [C16Pyr][Cl] demonstrated to be more toxic to all the test organisms than [C2OHMIM][Cl]. [C16Pyr][Cl] EC50 values varied between 0.0000205 and 35.404 mM. [C2OHMIM][Cl] EC50 values varied between 3.635 and 111.97 mM. [C16Pyr][Cl] hazard classification varied from relatively harmless for A. cepa to super toxic to D. magna. [C2OHMIM][Cl] hazard classification varied from relatively harmless for all test systems to practically nontoxic to D. magna. It was also shown that D. magna demonstrated the highest sensitivity for both ILs. The present results showed to be useful to understand ILs toxicity profile and to provide additional information for the design of safer compounds.Os líquidos iónicos (ILS) são sais que são estáveis acima da sua temperatura de fusão e são constituídos exclusivamente por iões (um catião orgânico ou inorgânico). Esta classe de substâncias químicas desperta considerável interesse devido às suas propriedades únicas e modificáveis. Devido ao crescente interesse nestes compostos, é previsível um aumento da sua produção e uso á escala industrial, o que pode resultar na libertação destes compostos no meio ambiente. Nos últimos anos, os ILS tem sido usados como uma alternativa aos solventes orgânicos convencionais, no entanto, poucos dados existem sobre a sua toxicidade e ecotoxicidade. O presente trabalho tem como objetivo avaliar o perfil ecotoxicológico de um IL derivado do imidazólio, o cloreto de 1-(2-hidroxietil)-3-metilmidazólio ([C2OHMIM][C1]), e um IL derivado do piridínio, o cloreto de cetilpiridínio ([C16Pyr][C1]). A avaliação ecotoxicológica foi realizada utilizando uma bateria de organismos teste de diferentes níveis tróficos: Chlorella vulgaris, Daphnia magna, Artemia salina, Lactuca sativa e Allium cepa. [C16Pyr][C1] demonstrou maior toxicidade para todos os organismos teste do que o [C2OHMIM][C1]. Os valore de EC50 para o [C16Pyr][C1] variaram entre 0.0000205 e 35.404mM. Os valores de EC50 para o [C2OHMIM][C1] variaram entre 3.635 e 111.97mM. Com base nos resultados, a classificação do [C16Pyr][C1] variou de relativamente inofensivo para a A. Cepa a super tóxico para a D. magna. A classificação do [C2OHMIM][C1] variou de relativamente inofensivo para todos os organismos teste a praticamente não tóxico para a D. magna. Foi também demonstrado que a D. magna é o organismo mais sensível a ambos os ILs testados. Os resultados do presente trabalho contribuem para melhor conhecer o perfil ecotoxicológico dos ILs e para fornecer informação adicional para a criação de compostos químicos mais seguros

Vetikad Pseudokircheriella subcapitata kemikaalide ja sünteetiliste nanoosakeste keskkonnaohtlikkuse hindamisel

Vetikad on peamised fotosünteesivad organismid veekogudes, tootes umbes poole Maa primaarproduktsioonist. Seeõttu on oluline keskkonnasaastuse mõju vetikate kasvule. Vetikad on ka head keskkonnatoksikoloogia mudelorganismid, kuna nad on tundlikud paljudele kemikaalidele ja neid on lihtne laboratoorsetes tingimustes kasvatada. Käesolevas doktoritöös täiustati OECD 201 suuniseid järgivat vetikate P. subcapitata kasvu pärssimise testi. Täiustamisel peeti silmas, et meetod sobiks lisaks vees hästi lahustuvate kemikaalide toksilisuse analüüsiks ka vees halvasti lahustuvate ainete ja osakesi sisaldavate keskkonnaproovide uurimiseks, sh ka suuremahuliseks testimiseks. Täiustatud testmetoodikat rakendati kolmes uuringus: (i) Raskemetallidega (Zn, Cd, Pb) saastunud metallisulatustehaste ümbruse muldade uuring näitas, et vaatamata kõrgetele Zn kontsentratsioonidele mulla vee-ekstraktides, mis pidanuksid olema vetikale mürgised, oli P. subcapitata kasv neis võrreldav kontrolliga. Mullasuspensioonid, mis sisaldasid tunduvalt enam raskemetalle kui vastavad vee-ekstraktid isegi stimuleerisid vetikate kasvu võrreldes vetikate kasvuga kontroll-lahuses. Samas, kui analüüsiti puhtast ja metallidega saastatud mullast valmistatud segusid, ilmnes mullaosakestele seotud metallide doosist sõltuv kahjulik mõju vetikatele. Seega tuleks mullaproovide toksilisuse hindamisel vetikatele võrdluseks kasutada samade füüsikalis-keemiliste omadustega puhast mulda. (ii) ZnO, TiO2 ja CuO nanoosakeste mõjude hindamine vetikate P. subcapitata kasvule näitas, et ZnO ja CuO nanoosakesed olid vetikatele ’väga toksilised’, kuna pärssisid vetikate kasvu juba väga madalates kontsentratsioonides: vastavad 72-tunni EC50 väärtused olid 0,052 mg/l ja 0,89 mg/l. TiO2 nanoosaksesed inhibeerisid vetikate kasvu tunduvalt kõrgemates kontsentratsioonides (EC50=9,9 mg/l), olles vetikatele umbes 6 korda toksilisemad kui vastavad mikroosakesed, pärssides vetikate kasvu tänu nende seondumisele vetikarakkudele. Nominaalsete kontsentratsioonide põhjal olid CuO nanoosakesed 16 korda toksilisemad kui vastavad mikroosakesed, samas kui ZnO puhul olid ühtviisi väga mürgised nii nano- kui mikroosakesed. Lahustunud Zn ja Cu analüüs vetikate kasvukeskkonnast näitas, et ZnO ja CuO osakeste vetikate kasvu pärssiv toime oli seotud osakestest leostunud metalli-ioonidega. Kirjeldatud töö oli esimene CuO nanoosakeste toksilisuse uuring vetikatele. (iii) Konstrueeriti struktuur-aktiivsussõltuvuste (QSAR) analüüsi võimaldav kemikaalipaneel, mis koosnes 58st eri positsioonides erinevalt asendatud aniliinist ja fenoolist. Analüüsides nende toksilisust vetikatele P. subcapitata saadi väikese katseveaga andmestik, mis sisaldas 48 seni avaldamata EC50 väärtust. Ehkki analüüsitud molekulid olid struktuurselt sarnased, erines nende toksilisus vetikatele kahe suurusjärgu võrra, jäädes vahemikku 1,43 mg/l (3,4,5-trikloroaniliin) kuni 197 mg/l (fenool). Uuritud ainete toksilisus sõltus asendajate tüübist (kloro-, metüül-, etüül-), arvust (mono-, di-, tri-) ja asendist (orto-, meta-, para-). Reeglina kaasnes suurema asendajate arvuga ka suurem toksilisus. Kloro-asendatud molekulid olid üldiselt toksilisemad kui alküülrühmadega asendatud analoogid. Andmetest selgusid ka asendajate positsioonist tulenevad efektid, nii näiteks suurendas asendaja para-asendis peaagu kõigi ainete toksilisust, samas kui orto-asendusega analoogid olid kõige vähem toksilised. Näidati ka, et hüdrofoobsuse ja toksilisuse seos on aniliinide ja fenoolide puhul erinev. Antud töös täiustatud vetikate kasvu inhibitsoonil põhinev ainete toksilisuse hindamise meetod osutus sobivaks ka vees lahustumatuid osakesi sisaldavate proovide hindamiseks ning võimaldas väikese töökuluga analüüsida suurt hulka proove. See omakorda võimaldab struktuur-aktiivsus sõltuvuste täiustamist, kuna vetika kasvu inhibitsiooni andmeseeriad on seni olnud küllaltki piiratud. Mainitud meetodid on vajalikud kemikaalide keskkonnaohtuse hindamiseks ning möödapääsmatud kemikaale reguleeriva määruse REACH rakendamiseks.Publication of the thesis is supported by Estonian University of Life Sciences, by the Doctoral School of Earth Sciences and Ecology created under the auspices of European Social Fund and by the EU 6th Framework Integrated Project OSIRIS, contract no. GOCE-CT-2007-03701

Characterizing the Effects of Thermochemical Bioenergy Production Processes on Emerging Contaminants and Wastewater Reuse Potential

The primary objective of this research was to improve our understanding of the water quality effects of thermochemical bioenergy production processes that can be applied to wet organic-laden wastes, such as animal manures, municipal wastewater, and food processing wastes. In particular, we analyzed the impacts of a novel integrated process combining algal wastewater treatment with hydrothermal liquefaction (HTL) on the fate of emerging bioactive contaminants (e.g., pharmaceuticals, estrogenic compounds, antibiotic-resistance genes, etc.) and the potential for wastewater reuse. We hypothesized and then confirmed that the elevated temperature and pressure of an HTL process can effectively convert the bioactive organic compounds into bioenergy products or otherwise break them down to inactive forms. High performance liquid chromatography (HPLC) with a photodiode array (PDA) detector was used to quantify emerging contaminants (florfenicol, ceftiofur, and estrone) before and after HTL treatment showed the removal of tested bioactive compounds to below detection limits when HTL was operated at 250°C for 60 min or at 300°C for ≥ 15 min. Complete breakdown or inactivation of antibiotic-resistance genes in wastewaters by the HTL process was also obtained at all tested HTL conditions (250-300°C, 15-60 min reaction time). The presence of HTL feedstocks such as swine manure or Spirulina algae reduced the removal of bioactive compounds and plasmid DNA when HTL was operated at 250°C for a short retention time (15 min). However, this effect was minimal when HTL was operated at 250°C for 60 min or at 300°C for ≥ 15 min. Detailed analysis of the aqueous product of HTL, also called HTL wastewater (HTL-WW), showed the occurrence of hundreds of nitrogenous organic compounds (NOCs). Reference materials for nine of the most significant NOC peaks were obtained and used to positively identify and quantify their concentrations. The chronic cytotoxicity effects of these NOCs were evaluated using a Chinese hamster ovary (CHO) cell assay, and found that the rank order for chronic cytotoxicity of these NOCs was 3-dimethylaminophenol > 2,2,6,6-tetramethyl-4-piperidinone > 2,6-dimethyl-3-pyridinol > 2-picoline > pyridine > 1-methyl-2-pyrrolidinone > σ-valerolactam > 2-pyrrolidinone > ε-caprolactam. However, none of the individual NOC compounds exhibited cytotoxicity at concentrations found in HTL-WW. In contrast, the complete mixture of organics extracted from HTL-WW showed significant cytotoxicity, with our results indicating that only 7.5% of HTL-WW would induce a 50% reduction in CHO cell density. Further testing showed three out of eight tested NOCs could cause 50% inhibition of algal growth at their detected concentration in HTL-WW. In addition, we found that treatment of HTL-WW with a batch-fed algal bioreactor could effectively remove more than 99% of NOCs after seven days of operation and 40% of the CHO chronic toxicity. We also found that over 90% of the CHO toxicity could be eliminated by filtering with granular activated carbon (GAC) after algal bioreactor treatment. These post-treatments of HTL-WW synergistically integrate with HTL bioenergy production because both the GAC and the algal biomass from the bioreactor can potentially be fed back into HTL to generate additional biocrude oil, which facilitates beneficial reuse of the nutrient content of HTL-WW. All in all, this novel treatment approach offers significant advantages for reducing the potential toxicity risks associated with byproducts of HTL bioenergy production and for improving wastewater effluent quality for subsequent water reuse applications.Illinois Sustainable Technology Center Sponsored Research Program ; Grant No. HWR12226Ope

Revealing fungal activity in the presence of ionic liquids

Dissertation presented to obtain the Ph.D degree in BiochemistryIonic liquids constitute a vast and heterogeneous group of chemicals, generally non-volatile and of high solvent quality. They are already used in industrial processes; future applications depend heavily on conscious design of ionic liquids. Given especially the global demand for sustainable chemicals, understanding environmental risks is a priority, necessitating a multidisciplinary research approach, covering a broad range of disciplines from biology to chemistry. Ascomycota fungi are highly suitable model organisms, especially due to their environmental ubiquity and important role in the biotic decay of pollutants. This thesis reports the first ever use of Ascomycota fungi to investigate ionic liquids ecotoxicity and environmental persistence. Fungal strains of Penicillium and Aspergillus were in general found to be more tolerant to ionic liquids containing imidazolium, pyridinium, pyrrolidinium, cholinium or phosphonium cations, than any other microorganism tested to date (Chapters II, III and IV). The capacity of the strains to tolerate the ionic liquids tested was apparently correlated to their phylogeny. Ionic liquid toxicity was evaluated using common parameters, such as growth inhibition and death. Less frequently evaluated parameters were also analysed, including monitoring of the integrity of the cellular boundaries of fungal conidia by microscopy (Chapter IV) and determining the diffusible fungal metabolome by ESI-MS and LC (Chapter II and V). Overall, these data significantly contribute to current understanding of structure-activity relationships in ionic liquids. For example toxicity is apparently a function of alkyl chain length of both anion and cation (Chapters III and IV, respectively). A critical review of current understanding of toxicity and environmental impact of the principal ionic liquid groups made it clear that the common generalisation of ionic liquids being either “green” or “toxic”(...)Financial support provided by Fundação para a Ciência e Tecnologia (fellowship BD 31451/2006). The work was partially supported by a grant from Iceland, Liechtenstein and Norway through the EEA financial mechanism (Project PT015)

Environmental, health, and safety assessment of chemical alternatives during early process design: The role of predictive modeling and streamlined techniques

Industrial chemicals are important for many aspects of modern life, though they can be harmful to the environment and human health. Environmental or safety concerns identified during the early design and selection of chemicals could motivate choices as to safer alternatives and process setups. There is a growing interest in developing more rapid, and streamlined assessment methods to obtain a first indication of the potential impacts linked to the nature and use of industrial chemicals. This work applies predictive modeling and streamlined techniques to estimate the potential environmental, health, and safety hazards associated with specific chemical structures. The assessment is performed during the design and selection of promising candidates for a particular process as part of the computer-aided molecular design (CAMD) and process setup. The case of phase-change solvents used for post-combustion carbon capture is examined. Furthermore, the refinement of predictive models through the incorporation of knowledge already existing in the field (prior knowledge) is investigated. A procedure for knowledge extraction from scientific articles that applies text mining is proposed. The results show that incorporating impact assessment criteria into the CAMD facilitates the molecular design by enriching the Pareto front of candidates. The use of predictive models that estimate molecular properties, such as acute aquatic toxicity, bioconcentration, and persistency are found to support the identification of the optimal solvents for CO2 capture. Given the role of sustainability-related properties in tasks such as CAMD, the improved performance and the interpretability of the aquatic toxicity predictive models developed here and using prior knowledge are important. The process level assessment of the phase-change solvent systems indicated that phase-change solvent alternatives could provide benefits, not only in terms of reduced energy consumption but also lower impacts on human health and the environment. \ua0However, the degradation behaviors of these compounds should be properly assessed and controlled to ensure beneficial performances compared to conventional carbon capture solvents. Overall, predictive modeling and streamlined life-cycle assessments (LCAs), as well as environmental, health, and safety evaluation methods were revealed to be valuable for defining the critical aspects that influence the potential impacts of chemicals and in supporting decisions concerning the molecular and process designs

Produção de lipase por fermentação extractiva com líquidos iónicos

Doutoramento em Engenharia QuímicaNovos processos fermentativos, designados por processos de Fermentação Extractiva, são caracterizados por apresentarem etapas de produção e extracção em simultâneo. A extracção líquido-líquido como técnica de separação é amplamente usado na indústria química pela sua simplicidade, baixo custo e facilidade de extrapolação de escala. No entanto o uso de solventes orgânicos nestes processos potencia os riscos ocupacionais e ambientais. Neste contexto, o uso de sistemas de duas fases aquosas baseados em líquidos iónicos, apresenta-se como uma técnica eficaz para a separação e purificação de produtos biológicos. Este trabalho apresenta um estudo integrado sobre o uso de líquidos iónicos não aromáticos foram determinados. A capacidade para a formação de sistemas de duas fases foi estudada para uma vasta gama de líquidos iónicos hidrofílicos com diferentes aniões, catiões e cadeias alqúilicas. A capacidade de separação e purificação de um largo conjunto de líquidos iónicos foi posteriormente investigada, recorrendo-se ao uso de várias biomoléculas modelo de diferentes graus de complexidade, um amino-acido (L-triptofano) e duas enzimas lipolíticas (enzima produzida pela bactéria Bacillus sp. e Candida antarctica lipase B – CaLB). Esta última foi ainda usada para um estudo de biocompatibilidade, tendo sido determinado o efeito de diferentes LIs hidrofílicos na sua actividade enzimática. Este trabalho mostra um estudo ecotoxicológico duma vasta gama de líquidos iónicos e espécies aquáticas, inseridas em diversos níveis tróficos. A bioacumulação foi investigada através do estudo dos coeficientes de distribuição 1-octanol-água (Dow).Novel fermentation processes characterized by the simultaneously production and separation are known as Extractive Fermentations. Liquid-liquid extraction is a separation technique that can be used for this purpose. These processes are widely used in the chemical industry owing to its simplicity, low costs and ease of scale-up. However, most extraction processes include the use of organic solvents, which have both environmental and occupational risks associated to their use. This makes these extraction systems inappropriate for the development of environmental-friendly technologies. In this context, the use of aqueous two-phase systems (ATPS) based in Ionic Liquids (ILs) appears as an effective and viable method for the separation and purification of biological products. The present work reports an integrated study on the use of ILs as alternative solvents in Fermentation processes. Original data on the solubility of nonaromatic ILs in water are reported. The ability of several ILs for the formation of aqueous two-phase systems was studied for a wide range of hydrophilic ILs with different anions, cations and alkyl chains. The separation and purification capacity of a large set of ILs was then investigated, using different biomolecules as models with distinct structural complexities, one amino-acid (Ltryptophan) and two lipolytic enzymes (an enzyme produced by the bacterium Bacillus sp. and Candida antarctica lipase B – CaLB). CaLB was also used on a study of biocompatibility, where the effect of various hydrophilic ILs on its enzymatic activity was addressed. Finally, this work reports an ecotoxicological study for a large number of ILs and aquatic species, included in different trophic levels. The bioaccumulation data was investigated by the study of the 1-octanol-water distribution coefficients (Dow)