In vivo and ex vivo percutaneous absorption of [14C]-bisphenol A in rats: a possible extrapolation to human absorption?

Bisphenol A (BPA) is a monomer used mainly in the synthesis of polycarbonates and epoxy resins. Percutaneous absorption is the second source of exposure, after inhalation, in the work environment. However, studies on this route of absorption are lacking or incomplete. In this study, percutaneous BPA absorption was measured in vivo and ex vivo in the rat, and ex vivo in humans. An approximately 12-fold difference in permeability between rat skin and human skin was found, with permeability being higher in the rat. In addition, inter- and intra-individual variability of up to tenfold was observed in humans. No accumulation of BPA in the skin was found during exposure. The skin clearance rate following exposure was estimated at 0.4 μg/cm²/h. Ex vivo and in vivo percutaneous absorption fluxes of BPA in the rat were in the same range (about 2.0 μg/cm²/h), suggesting that extrapolation to the in vivo situation in humans may be possible. The European tolerable daily intake (TDI) of BPA is 50 μg/kg body weight. However, many research projects have highlighted the significant effects of BPA in rodents at doses lower than 10 μg/kg/day. A 1-h occupational exposure over 2,000 cm² (forearms and hands) may lead to a BPA absorption of 4 μg/kg/day. This is 8% of the European TDI and is very close to the value at which effects have been observed in animals. This absorption must therefore be taken into account when evaluating risks of BPA exposure, at least until more relevant results on the toxicity of BPA in humans are available

Nanotechnology in perspective. Risks for man and the environment

Het Kennis- en Informatiepunt Risico's van Nanotechnologie (KIR-nano) van het RIVM heeft de potentiele risico's van blootstelling van gefabriceerde, vrije, onafbreekbare en onoplosbare nanodeeltjes in kaart gebracht. In dit rapport worden de risico's voor de mens als werknemer, patient en consument behandeld, evenals risico's voor het milieu. Drie toepassingsgebieden zijn daarbij relevant: geneesmiddelen en medische technologie, voedselproductie en consumentenproducten. De huidige stand van zaken van de wetenschap laat zien dat risico's niet uit te sluiten zijn. Er ontbreekt echter nog veel kennis om de risico's even goed in te kunnen schatten als voor 'chemische stoffen niet in nanovorm'. Toch zijn er al vele honderden producten waarin nanomaterialen zijn verwerkt op de markt. Dit vereist op korte termijn veel onderzoek naar de blootstelling en toxiciteit van deze materialen. Helaas is het aantal onderzoeksvragen dusdanig groot en fundamenteel van aard dat het nog jaren zal duren voordat alle informatie is vergaard. KIR-nano adviseert daarom het onderzoek vooral te richten op die vragen die cruciale informatie voor de risicobeoordeling voor mens en milieu bieden. Afhankelijk van het perspectief van werknemer, consument, patient of milieu zijn oplossingsrichtingen gedefinieerd voor het beheersen van de risico's. Informatie die in de streng gereguleerde wereld van medische toepassingen wordt gegenereerd kan met name vanuit methodologisch oogpunt zeer waardevol zijn voor andere toepassingsgebieden, waar de dossiervereisten en dus veelal ook de informatievergaring (veel) beperkter voor zijn. Kernbegrippen voor de komende jaren zijn samen te vatten onder KOKOS: Kennis vergroten en uitwisselen om dubbeling van onderzoek te voorkomen, Oplossingsrichtingen en risicomanagement, Keuzes maken in bijdragen vanuit Nederland aan dit onderzoeksveld, Onderzoek & Ontwikkeling, en Samenwerking bevorderen tussen wet- en regelgevende kaders, wetenschap en bedrijfsleven.The Knowledge and Information Risks Nanotechnology (KIR nano), a Dutch national government-supported observation organization based at RIVM, has provided an overview of the potential risks to both man and the environment of exposure to nanoparticles. The focus is on free, non-degradable and insoluble nanoparticles present in medical applications, food, consumer products and the environment. Scientific data compiled to date demonstrate that negative effects of exposure to nanoparticles cannot be excluded. However, much more information is required to be able to estimate the risks of nanoparticles equally well as those of other (not nano) chemicals. Nevertheless, hundreds of products containing nanomaterials are currently available commercially, a situation which clearly necessitates that the exposure and toxicity of these materials be investigated in the near future. Unfortunately, the research questions to be answered are so numerous that it will take years to compile the relevant data. The advice of the KIR nano is to focus research primarily on those questions that provide information critical to the assessment of risks to man and the environment. Dependent on the perspective - worker, consumer, patient, or the environment - the points of departure can then be defined for controlling (or limiting) the risks. Information (eg. on methodology) generated in the strongly regulated world of medical applications can be a very valuable asset in other (research) areas of application, where the requirements for dossiers and compiling of pertinent data are not as exacting. Core concepts for the upcoming years include expanding our knowledge of nanoparticles and making this knowledge easily available to avoid any duplication of research, identifying and where necessary taking the appropriate risk management measures, choosing the areas of research in which the Netherlands wishes to contribute to this field, supporting Research & Development and promoting collaboration between (semi)government organs/agencies, science and industry.VROMVWSSZ

Skin Sensitisation and Epidermal Disposition: The Relevance of Epidermal Disposition for Sensitisation Hazard Identification and Risk Assessment

This is the XXth report of a series of workshops organised by the European Centre for the Validation of Alternative Methods (ECVAM). The main goal of ECVAM, as defined in 1993 by its Scientific Advisory Committee, is to promote the scientific and regulatory acceptance of alternative methods which have scientific relevance and which reduce, refine or replace the use of laboratory animals. One of the first priorities set by ECVAM was the implementation of procedures that would enable it to become well informed about the state-of-the-art of non-animal test development and validation, and the potential for the possible incorporation of alternative tests into regulatory procedures. It was decided that this would be best achieved by the organisation of ECVAM workshops each addressing a specific topic, and at which selected groups of independent international experts would review the current status of various types of in vitro tests and their potential uses, and make recommendations about the best ways forward*. A Workshop on Skin Sensitisation and Epidermal Disposition was held at ECVAM (Ispra, Italy) on 30/31 January 2006 under the chairmanship of David Basketter, Unilever Safety and Environmental Assurance Centre, UK. The current status of approaches used to measure the disposition of chemicals in skin compartments was reviewed, with particular emphasis on proposing recommendations on how best to use such information to reduce refine and/or eliminate the need for animal testing, according to the 3 Rs principle. The key focus was the relevance of information on epidermal disposition and how best to integrate such information into non-animal testing strategies for skin sensitisation.JRC.I.2-Validation of biomedical testing method