Inter-laboratory comparison of nanoparticle size measurements using dynamic light scattering and differential centrifugal sedimentation

Nanoparticle in vitro toxicity studies often report contradictory results with one main reason being insufficient material characterization. In particular the characterization of nanoparticles in biological media remains challenging. Our aim was to provide robust protocols for two of the most commonly applied techniques for particle sizing, i.e. dynamic light scattering (DLS) and differential centrifugal sedimentation (DCS) that should be readily applicable also for users not specialized in nanoparticle physico-chemical characterization. A large number of participants (40, although not all participated in all rounds) were recruited for a series of inter-laboratory comparison (ILC) studies covering many different instrument types, commercial and custom-built, as another possible source of variation. ILCs were organized in a consecutive manner starting with dispersions in water employing well-characterized near-spherical silica nanoparticles (nominal 19 nm and 100 nm diameter) and two types of functionalized spherical polystyrene nanoparticles (nominal 50 nm diameter). At first each laboratory used their in-house established procedures. In particular for the 19 nm silica particles, the reproducibility of the methods was unacceptably high (reported results were between 10 nm and 50 nm). When comparing the results of the first ILC round it was observed that the DCS methods performed significantly worse than the DLS methods, thus emphasizing the need for standard operating procedures (SOPs). SOPs have been developed by four expert laboratories but were tested for robustness by a larger number of independent users in a second ILC (11 for DLS and 4 for DCS). In a similar approach another SOP for complex biological fluids, i.e. cell culture medium containing serum was developed, again confirmed via an ILC with 8 participating laboratories. Our study confirms that well-established and fit-for-purpose SOPs are indispensable for obtaining reliable and comparable particle size data. Our results also show that these SOPs must be optimized with respect to the intended measurement system (e.g. particle size technique, type of dispersant) and that they must be sufficiently detailed (e.g. avoiding ambiguity regarding measurand definition, etc.). SOPs may be developed by a small number of expert laboratories but for their widespread applicability they need to be verified by a larger number of laboratories

N-ethylmorpholine

W normalnych warunkach ciśnienia i temperatury N-etylomorfolina (N-EM) jest bezbarwną cieczą o amoniakalnym zapachu. Jest używana w przemyśle jako katalizator pianek poliuretanowych, a także jako produkt pośredni w produkcji barwników kadziowych, środków farmaceutycznych, emulgatorów i przyspieszaczy do tworzyw gumowych. Wykorzystywana jest również w syntezie organicznej jako rozpuszczalnik dla tłuszczów i olejów oraz regulator pH. N-Etylomorfolina może wchłaniać się przez nieuszkodzoną skórę, drogą pokarmową i oddechową. Jest związkiem słabo toksycznym u zwierząt po podaniu dożołądkowym i narażeniu inhalacyjnym. Odznacza się działaniem drażniącym na oczy oraz błonę śluzową nosa i tchawicy. Wykazuje działanie mutagenne w testach na S. typhimurium. Brak jest danych literaturowych, wskazujących na jej działanie kancerogenne i teratogenne oraz toksyczne działanie na rozrodczość. Według istniejących danych, najważniejszym objawem szkodliwym u ludzi po narażeniu na N-etylomorfolinę jest działanie drażniące na oczy (obrzęk rogówki) oraz błonę śluzową nosa i tchawicy. W jednym z badań zaobserwowano, u robotników narażonych na N-EM o stężeniach 188 mg/m3 (40 ppm) i większych, obrzęk rogówki. Zmiany te pojawiły się pod koniec zmiany roboczej i ustąpiły w ciągu 3 - 4 h po przerwaniu narażenia. Opierając się na powyższym doniesieniu, a także przyjmując za wartość LOAEL stężenie N-EM równe 188 mg/m3 oraz wartości współczynników, wynikających z: przejścia z wartości LOAEL do wartości NOAEL równego 2, różnic we wrażliwości na działanie drażniące N-etylomorfoliny w populacji narażonej równego 2 oraz niekompletności danych równego 2, proponujemy przyjąć wartość NDS N-etylomorfoliny obliczoną na podstawie wzoru: NDS = 188 mg/m3/8 = 23,5 mg/m3 - 23 mg/m3. Wartość NDS N-EM na poziomie 23 mg/m3 powinna chronić narażone osoby przed wystąpieniem ewentualnych zmian zapalno-obrzękowych rogówki, jak również przed podrażnieniem układu oddechowgo. Ze względu na drażniące działanie N-EM, proponuje się przyjąć wartość NDSCh tego związku, wynoszącą 2-krotną wartość NDS, czyli 46 mg/m3.Under normal conditions of pressure and temperature N-ethylmorpholine (N-EM) constitutes a colorless liquid with ammonia-like odor. In industry it is used as urethane foam catalyst, intermediate for dyestuffs, pharmaceuticals, rubber accelerators, emulsifying agents, as well as a pH regulator and a solvent for dyes, resins, oils. N-EM can be absorbed through unbroken skin, digestive and respiratory tract. It is relatively poorly toxic after oral and inhalation exposure. Corneal, nasal and tracheal irritation have been reported. A direct mutagenic effect was found with N-EM in mutagenicity tests with Salmonella typhimurium strains TA1535 and TA100, with and without metabolic activation. There are no scientific data indicating carcinogenic, teratogenic or developmental toxicity of N-EM. According to existing data irritation to the eyes (corneal oedema), nose, and throat are the most important adverse effects. Corneal edema was observed in workers exposed at 188 mg/m3 (40 ppm) and more N-EM for several hours. The lesions appeared near the end of the work shift and cleared within 3 to 4 hr after cessation of exposure. Based on the study and taking into account the following uncertainty factors: 2 for calculation of NOAEL from LOAEL, 2 for differences in susceptibility of individuals, and 2 for incompleteness of data, the TLV value for Nethylmorpholine is proposed as 23 mg/m3 and the STEL value as 46 mg/m3

Cytotoxicity and mutagenic activity of moulds colonizing building materials

Materiały konferencyjne zostały wydane jako numer specjalny czasopisma "Ochrona przed Korozją - 9s/A/2006".Badania obejmowały analizę mikologiczną oraz toksykologiczną ekstraktów z przegród budowlanych porażonych pleśniami (wykrywanie obecności mikotoksyn, ocena aktywności cytotoksycznej i mutagennej). Stwierdzono, że pleśnie na przegrodach budowlanych nie wytwarzały mikotoksyn mimo aktywnego wzrostu. Badane ekstrakty nie wykazywały również efektu cytotoksycznego ani mutagennego. Cecha toksynotwórczości ujawniła się dopiero w warunkach laboratoryjnych po hodowli na pożywce mikrobiologicznej YES oraz na materiałach budowlanych w warunkach kontrolowanej wilgotności z dodatkiem kurzu. Brak tworzenia mykotoksyn w warunkach budynku może być spowodowane obecnością innej towarzyszącej mikroflory. Stwierdzono, iż cytotoksyczność prób na materiałach celulozowych (drewno, płyta gipsowo-kartonowa, tapeta) wynika z obecności wytworzonej przez A.ochraceus ochratoksyny A. Ekstrakty z wykładziny dywanowej wykazywały właściwości cytotoksyczne chociaż nie wykryto w nich ochratoksyny A, co może wskazywać na obecność innych metabolitów. Spadek żywotności mysich fibroblastów 3T3-L 1 narażanych na ekstrakty z cementu i skóry spowodowany był najprawdopodobniej właściwościami chemicznymi tych materiałów.Mycological analysis, toxicological analysis of mouldy dwellings partitions (mycotoxins presence analysis, cytotoxicity and mutagenie activity of mouldy extracts from buildings partitions) were investigated. lt has been found that moulds didn 't produce mycotoxins on buildings partitions, in spite active growth of these. Mouldy extracts weren't cytotoxicity and mutagenie. Toxicity of moulds has appeared in laboratory condition after growth on microbial medium YES and after cultivation on buildings materials with controlled humidity and addition of dust. It has been found that cytotoxicity of mouldy cellulolitic materials (wood, carton-board plate, wallpaper) was resulted of ochratoxin A production by A.ochraceus. Extracts from mouldy carpet lining were cytotoxicity, but didn 't detect ochratoxin A, it has been showed on presence of another metabolites produced by moulds. The reduce of vitality mouse fibroblast 3T3-Ll after exposition to extracts from cement and leather was caused by chemical compounds property of these

Grouping and read-across in an regulatory-wise case studies to predict nanomaterials ecotoxicity

International audienc

"SCCS OPINION ON the safety of Butylphenyl methylpropional (p-BMHCA) in cosmetic products - Submission II"SCCS/1591/17 - Final version

International audience"SCCS OPINION ON the safety of Butylphenyl methylpropional (p-BMHCA) in cosmetic products - Submission II"SCCS/1591/17 - Final versionFor the Preliminary Opinion : SCCS Members ; U. Bernauer, L. Bodin, L. Celleno, Q. Chaudhry, P.J. Coenraads, M. Dusinska, J. Ezendam, E. Gaffet, C. L. Galli, B. Granum, E. Panteri, V. Rogiers, Ch. Rousselle, M. Stępnik (Rapporteur), T. Vanhaecke, S. WijnhovenFor the Final Opinion : SCCS Members : U. Bernauer, L. Bodin, Q. Chaudhry, P.J. Coenraads, M. Dusinska, J. Ezendam, E. Gaffet, C. L. Galli, B. Granum, E. Panteri, V. Rogiers, Ch. Rousselle, M. Stępnik (Rapporteur), T. Vanhaecke, S. WijnhovenThe SCCS adopted this Opinion by written procedure on 10 May 2019 (68 pages)https://ec.europa.eu/health/sites/health/files/scientific_committees/consumer_safety/docs/sccs_o_213.pd

SCCS OPINION on Allergy Alert Test (AAT) as a proof-of-concept study"SCCS/1607/19 - Final Opinion

"SCCS OPINION on Allergy Alert Test (AAT) as a proof-of-concept study"SCCS/1607/19 - Final OpinionU. Bernauer, L. Bodin, Q. Chaudhry, M. Dusinska, J. Ezendam, E. Gaffet, C. L. Galli, B. Granum, E. Panteri, V. Rogiers, Ch. Rousselle, M. Stępnik (Rapporteur), T. Vanhaecke, S. Wijnhoven, A. Koutsodimou, A. Simonnard, W. UterMise en ligne le 11 Septembre 2019The SCCS adopted the final Opinion by written procedure on 10 September 2019 (42 Pages

Inter-laboratory comparison of nanoparticle size measurements using dynamic light scattering and differential centrifugal sedimentation

Nanoparticle in vitro toxicity studies often report contradictory results with one main reason being insufficient material characterization. In particular the characterization of nanoparticles in biological media remains challenging. Our aim was to provide robust protocols for two of the most commonly applied techniques for particle sizing, i.e. dynamic light scattering (DLS) and differential centrifugal sedimentation (DCS) that should be readily applicable also for users not specialized in nanoparticle physico-chemical characterization. A large number of participants (40, although not all participated in all rounds) were recruited for a series of inter-laboratory comparison (ILC) studies covering many different instrument types, commercial and custom-built, as another possible source of variation. ILCs were organized in a consecutive manner starting with dispersions in water employing well-characterized near-spherical silica nanoparticles (nominal 19 nm and 100 nm diameter) and two types of functionalized spherical polystyrene nanoparticles (nominal 50 nm diameter). At first each laboratory used their in-house established procedures. In particular for the 19 nm silica particles, the reproducibility of the methods was unacceptably high (reported results were between 10 nm and 50 nm). When comparing the results of the first ILC round it was observed that the DCS methods performed significantly worse than the DLS methods, thus emphasizing the need for standard operating procedures (SOPs). SOPs have been developed by four expert laboratories but were tested for robustness by a larger number of independent users in a second ILC (11 for DLS and 4 for DCS). In a similar approach another SOP for complex biological fluids, i.e. cell culture medium containing serum was developed, again confirmed via an ILC with 8 participating laboratories. Our study confirms that well-established and fit-for-purpose SOPs are indispensable for obtaining reliable and comparable particle size data. Our results also show that these SOPs must be optimized with respect to the intended measurement system (e.g. particle size technique, type of dispersant) and that they must be sufficiently detailed (e.g. avoiding ambiguity regarding measurand definition, etc.). SOPs may be developed by a small number of expert laboratories but for their widespread applicability they need to be verified by a larger number of laboratories.This work has been supported by the EU FP7 Capacities project QualityNano (grant no. INFRA-2010-262163)

Inter-laboratory comparison of nanoparticle size measurements using dynamic light scattering and differential centrifugal sedimentation

Nanoparticle in vitro toxicity studies often report contradictory results with one main reason being insufficient material characterization. In particular the characterization of nanoparticles in biological media remains challenging. Our aim was to provide robust protocols for two of the most commonly applied techniques for particle sizing, i.e. dynamic light scattering (DLS) and differential centrifugal sedimentation (DCS) that should be readily applicable also for users not specialized in nanoparticle physico-chemical characterization. A large number of participants (40, although not all participated in all rounds) were recruited for a series of inter-laboratory comparison (ILC) studies covering many different instrument types, commercial and custom-built, as another possible source of variation. ILCs were organized in a consecutive manner starting with dispersions in water employing well-characterized near-spherical silica nanoparticles (nominal 19 nm and 100 nm diameter) and two types of functionalized spherical polystyrene nanoparticles (nominal 50 nm diameter). At first each laboratory used their in-house established procedures. In particular for the 19 nm silica particles, the reproducibility of the methods was unacceptably high (reported results were between 10 nm and 50 nm). When comparing the results of the first ILC round it was observed that the DCS methods performed significantly worse than the DLS methods, thus emphasizing the need for standard operating procedures (SOPs). SOPs have been developed by four expert laboratories but were tested for robustness by a larger number of independent users in a second ILC (11 for DLS and 4 for DCS). In a similar approach another SOP for complex biological fluids, i.e. cell culture medium containing serum was developed, again confirmed via an ILC with 8 participating laboratories. Our study confirms that well-established and fit-for-purpose SOPs are indispensable for obtaining reliable and comparable particle size data. Our results also show that these SOPs must be optimized with respect to the intended measurement system (e.g. particle size technique, type of dispersant) and that they must be sufficiently detailed (e.g. avoiding ambiguity regarding measurand definition, etc.). SOPs may be developed by a small number of expert laboratories but for their widespread applicability they need to be verified by a larger number of laboratories