Testing strategies for embryo-fetal toxicity of human pharmaceuticals. Animal models vs. in vitro approaches : A workshop report

Reproductive toxicity testing is characterized by high animal use. For registration of pharmaceutical compounds, developmental toxicity studies are usually conducted in both rat and rabbits. Efforts have been underway for a long time to design alternatives to animal use. Implementation has lagged, partly because of uncertainties about the applicability domain of the alternatives.     

Racism,Health Status,and Birth Outcomes: Results of a Participatory Community-Based Intervention and Health Survey

Many community-based participatory research (CBPR) partnerships address social determinants of health as a central consideration. However, research studies that explicitly address racism are scarce in the CBPR literature, and there is a dearth of available community-generated data to empirically examine how racism influences health disparities at the local level. In this paper, we provide results of a cross-sectional, population-based health survey conducted in the urban areas of Genesee and Saginaw Counties in Michigan to assess how a sustained community intervention to reduce racism and infant mortality influenced knowledge, beliefs, and experiences of racism and to explore how perceived racism is associated with self-rated health and birth outcomes. We used ANOVA and regression models to compare the responses of intervention participants and non-participants as well as African Americans and European Americans (N = 629). We found that intervention participants reported greater acknowledgment of the enduring and differential impact of racism in comparison to the non-intervention participants. Moreover, survey analyses revealed that racism was associated with health in the following ways: (1) experiences of racial discrimination predicted self-rated physical health, mental health, and smoking status; (2) perceived racism against one’s racial group predicted lower self-rated physical health; and (3) emotional responses to racism-related experiences were marginally associated with lower birth-weight births in the study sample. Our study bolsters the published findings on perceived racism and health outcomes and highlights the usefulness of CBPR and community surveys to empirically investigate racism as a social determinant of health.     

Automatic sorting of toxicological information into the IUCLID (International Uniform Chemical Information Database) endpoint-categories making use of the semantic search engine Go3R

The knowledge-based search engine Go3R, www.Go3R.org, has been developed to assist scientists from industry and regulatory authorities in collecting comprehensive toxicological information with a special focus on identifying available alternatives to animal testing. The semantic search paradigm of Go3R makes use of expert knowledge on 3Rs methods and regulatory toxicology, laid down in the ontology, a network of concepts, terms, and synonyms, to recognize the contents of documents. Search results are automatically sorted into a dynamic table of contents presented alongside the list of documents retrieved. This table of contents allows the user to quickly filter the set of documents by topics of interest. Documents containing hazard information are automatically assigned to a user interface following the endpoint-specific IUCLID5 categorization scheme required, e.g. for REACH registration dossiers. For this purpose, complex endpoint-specific search queries were compiled and integrated into the search engine (based upon a gold standard of 310 references that had been assigned manually to the different endpoint categories). Go3R sorts 87% of the references concordantly into the respective IUCLID5 categories. Currently, Go3R searches in the 22 million documents available in the PubMed and TOXNET databases. However, it can be customized to search in other databases including in-house databanks.     

The challenge of reproductive and developmental toxicology under REACH.

The European Union's REACH regulation has explicit requirements for reproductive and developmental toxicity data on all substances manufactured in or imported into the European Union at > or = 10 metric tons/year. Meeting the data requirements with whole-animal testing could result in the use of almost 22 million vertebrate animals for the registration of existing chemicals and cost up to several hundred thousand dollars per registered substance. The requirement for financial and animal resources can be reduced by the use of in vitro testing, quantitative structure-activity relationship models, and grouping of related substances. Although REACH strongly encourages these methods of avoiding vertebrate animal testing, it does not appear that in vitro testing or quantitative structure-activity relationship analysis will be able to replace whole-animal reproductive and developmental toxicity testing. Grouping of related compounds offers the possibility, perhaps in conjunction with in vitro testing and structure-activity analysis, of reducing vertebrate animal testing provided there is sufficient information on the related compounds and sufficient reason to believe that the related compounds will have similar toxicological properties. The designation of a substance as a reproductive or developmental toxicant follows criteria that do not consider the dose level of the substance at which reproductive or developmental effects occur, as long as excessive generalized toxicity does not occur. This method of labeling substances without consideration of effective dose level does not provide information on the actual risk of the chemical. Designation of a substance as a reproductive or developmental toxicant may have important implications under REACH and can be expected to result in the need to obtain authorization for marketing of the substance in the European Union.     

Defining occupational and consumer exposure limits for enzyme protein respiratory allergens under REACH

A wide range of substances have been recognized as sensitizing, either to the skin and/or to the respiratory tract. Many of these are useful materials, so to ensure that they can be used safely it is necessary to characterize the hazards and establish appropriate exposure limits. Under new EU legislation (REACH), there is a requirement to define a derived no effect level (DNEL). Where a DNEL cannot be established, e.g. for sensitizing substances, then a derived minimal effect level (DMEL) is recommended. For the bacterial and fungal enzymes which are well recognized respiratory sensitizers and have widespread use industrially as well as in a range of consumer products, a DMEL can be established by thorough retrospective review of occupational and consumer experience. In particular, setting the validated employee medical surveillance data against exposure records generated over an extended period of time is vital in informing the occupational DMEL. This experience shows that a long established limit of 60 ng/m³ for pure enzyme protein has been a successful starting point for the definition of occupational health limits for sensitization in the detergent industry. Application to this of adjustment factors has limited sensitization induction, avoided any meaningful risk of the elicitation of symptoms with known enzymes and provided an appropriate level of security for new enzymes whose potency has not been fully characterized. For example, in the detergent industry, this has led to general use of occupational exposure limits 3–10 times lower than the 60 ng/m³ starting point. In contrast, consumer exposure limits vary because the types of exposure themselves cover a wide range. The highest levels shown to be safe in use, 15 ng/m³, are associated with laundry trigger sprays, but very much lower levels (e.g. 0.01 ng/m³) are commonly associated with other types of safe exposure. Consumer limits typically will lie between these values and depend on the actual exposure associated with product use.     

Exposure-driven risk assessment: Applying exposure-based waiving of toxicity tests under REACH

The REACH Regulation 1907/2006/EC aims to improve knowledge of the potential risks to humans and the environment of the large number of chemicals produced and used in the EU. The testing requirements are likely to trigger numerous toxicological studies, potentially involving millions of experimental animals, despite the professed goal of REACH to reduce vertebrate testing. It may be necessary therefore to shift emphasis away from animal studies towards more pragmatic strategies, reserving animal tests for the substances of greatest concern. One approach is to waive certain tests based on levels of exposure to the substance. This review explores application of ‘Exposure-Based Waiving’ (EBW) of toxicity studies, with a particular focus on inhalation where possible, considering the potential qualitative and quantitative supporting arguments that might be made, including the use of thresholds of toxicological concern. Incorporating EBW into intelligent testing strategies for substance registration could advance the goals of REACH and the 3Rs (reduction, replacement and refinement of animals in research) by reducing the usage of animals in toxicity tests, whilst maintaining appropriate protection of human health and the environment. However greater regulatory evaluation, acceptance and guidance are required for EBW to achieve its full impact.     

Report from the EPAA workshop: In vitro ADME in safety testing used by EPAA industry sectors

There are now numerous in vitro and in silico ADME alternatives to in vivo assays but how do different industries incorporate them into their decision tree approaches for risk assessment, bearing in mind that the chemicals tested are intended for widely varying purposes? The extent of the use of animal tests is mainly driven by regulations or by the lack of a suitable in vitro model. Therefore, what considerations are needed for alternative models and how can they be improved so that they can be used as part of the risk assessment process? To address these issues, the European Partnership for Alternative Approaches to Animal Testing (EPAA) working group on prioritisation, promotion and implementation of the 3Rs research held a workshop in November, 2008 in Duesseldorf, Germany. Participants included different industry sectors such as pharmaceuticals, cosmetics, industrial- and agro-chemicals. This report describes the outcome of the discussions and recommendations (a) to reduce the number of animals used for determining the ADME properties of chemicals and (b) for considerations and actions regarding in vitro and in silico assays. These included: standardisation and promotion of in vitro assays so that they may become accepted by regulators; increased availability of industry in vivo kinetic data for a central database to increase the power of in silico predictions; expansion of the applicability domains of in vitro and in silico tools (which are not necessarily more applicable or even exclusive to one particular sector) and continued collaborations between regulators, academia and industry. A recommended immediate course of action was to establish an expert panel of users, developers and regulators to define the testing scope of models for different chemical classes. It was agreed by all participants that improvement and harmonization of alternative approaches is needed for all sectors and this will most effectively be achieved by stakeholders from different sectors sharing data.     

Oral bioaccessibility testing and read-across hazard assessment of nickel compounds

In vitro metal ion bioaccessibility, as a measure of bioavailability, can be used to read-across toxicity information from data-rich, source substances to data-poor, target substances. To meet the data requirements for oral systemic toxicity endpoints under the REACH Regulation in Europe, 12 nickel substances underwent bioaccessibility testing in stomach and intestinal fluids. A read-across paradigm was developed based on the correlation between gastric bioaccessibility and in vivo acute oral toxicity. The oral LD₅₀ values were well predicted by nickel release (R² = 0.91). Samples releasing <48% available nickel (mg Ni released/mg available Ni × 100) are predicted to have an LD₅₀ > 2000 mg/kg; while samples releasing >76% available nickel are expected to have an LD₅₀ between 300 and 2000 mg/kg. The hazard classifications (European Regulation on Classification, Labelling and Packaging of Chemical Substances and Mixtures) for all oral systemic endpoints were evaluated based on read-across from three source nickel compounds (sulfate, subsulfide, oxide). Samples releasing <48% available nickel were read-across from nickel oxides and subsulfide. Samples releasing >76% Ni were read-across from nickel sulfate. This assessment suggests that nickel chloride and dihydroxide should be less stringently classified and nickel sulfamate should receive a more stringent classification for oral systemic endpoints than currently assigned.     

Narrow-and-sharp or broad-and-blunt--regulations of hazardous chemicals in consumer products in the European Union

Chemicals are incorporated into a vast number of consumer products, and it has been recognized that considerable exposures of humans and the environment to chemicals are due to diffuse emissions from everyday products. Different approaches to the management of risks concerning chemicals in products are discussed on the international arena, but no general strategy has yet been adopted. The aim of this study is to investigate how health and environmental risks associated with chemicals in consumer products are currently managed in European Union legislations, mainly by the Toys Directive, the RoHS Directive, and REACH. Significant differences were found between the risk reduction strategies in these legislations, including substance prioritization, type of restrictions and requirements, and information dissemination to consumers. REACH regulates chemicals in products to a limited extent, and via quite complicated processes. Product-specific rules are therefore useful supplements to REACH for regulating chemicals in products. The combined effects of the RoHS and WEEE directives seem to be effective in promoting substitution of substances identified as problematic in electrical and electronic equipment, and it is recommended that the possibility to develop similar systems should be considered also for other product categories.