risk assessment

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Skin Sensitisation, Adverse Outcome Pathways and Alternatives

David Basketter

For toxicologists who are in any way associated with skin sensitisation, the last two decades have seen a series of fundamental changes. We have migrated from old-style guinea-pig assays, via the refined and reduced Local Lymph Node Assay (LLNA), to witness the imminent dominance of in vitro and in silico methods. Yet, over the same period, the use of the output data for human safety assurance has evolved from 'black box' risk assessment, via the quantitative risk assessment enabled by the LLNA measurement of potency, to a new period of relative uncertainty. This short review will endeavour to address these topics, all the while keeping a focus on three essential principles: a) that skin sensitisation potential is intrinsic in the molecular structure of the chemical; b) that test methods should have a mechanistic foundation; and finally c) that the only reason for undertaking any skin sensitisation work has to be the protection of human health.
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The Use of Peptide Reactivity Assays for Skin Sensitisation Hazard Identification and Risk Assessment

G. Frank Gerberick

Over the past 20 years or more, investigators have been developing non-animal test methods for use in assessing the skin sensitisation potential of chemicals. In parallel with this effort, the key biological events of skin sensitisation have been well-characterised in an Adverse Outcome Pathway (AOP) proposed by the Organisation for Economic Co-operation and Development (OECD). The key molecular initiating event of this AOP is haptenation or covalent modification of epidermal proteins. In this review, the strengths and limitations of the Direct Peptide Reactivity Assay (DPRA) are described, and the more recently developed Peroxidase Peptide Reactivity Assay (PPRA). The DPRA has been formally validated and incorporated into an OECD Test Guideline (TG442C). The DPRA shows promise for assisting in hazard identification as well as for assessing skin sensitisation potency when used in an integrated testing strategy.
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A Multi-faceted Approach to Achieving the Global Acceptance of Animal-free Research Methods

Jodie Melbourne, Patricia Bishop, Jeffrey Brown and Gilly Stoddart

In 2015, the PETA International Science Consortium Ltd. was awarded the Lush Training Prize for its broad approach to education and training on the effective use of human-relevant, non-animal research techniques. The prize was awarded for work that included hosting workshops and webinars, initiating in-person training sessions and developing educational resources. The Consortium works closely with industry and regulatory agencies to identify and overcome barriers to the validation and use of alternatives to animal testing, by using an approach that identifies, promotes and verifies the implementation of these methods. The Consortium's recent activities toward replacing tests on animals for nanomaterials, pesticides and medical devices, are described, as examples of projects with broad applicability aimed at large-scale regulatory change.
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Volatile Organic Compounds in Tartu Office Buildings

Argo Soon and Erkki Kähkönen

The volatile organic compounds (VOCs) that are emitted by many materials and activities are common indoor air pollutants. It is believed that VOCs might contribute to many adverse health effects, but there is scant evidence to support this. The difficulties involved in assessing the effects of VOCs involve both the chemistry of indoor air and the physiological responses in varying physical conditions. Inconsistent results of experimental studies and difficulties in performing longitudinal epidemiological studies have led to the conclusion that only higher concentrations (in the range of 1–25mg/m3) of VOCs in indoor air should be considered to relate to higher health risks. This pilot study provides evidence that there is no such risk in Estonian offices.
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Study of the Environmental Hazard Caused by the Oil Shale Industry Solid Waste

Lee Põllumaa, Alla Maloveryan, Marina Trapido, Helgi Sillak and Anne Kahru

The environmental hazard was studied of eight soil and solid waste samples originating from a region of Estonia heavily polluted by the oil shale industry. The samples were contaminated mainly with oil products (up to 7231mg/kg) and polycyclic aromatic hydrocarbons (PAHs; up to 434mg/kg). Concentrations of heavy metals and water-extractable phenols were low. The toxicities of the aqueous extracts of solid-phase samples were evaluated by using a battery of Toxkit tests (involving crustaceans, protozoa, rotifers and algae). Waste rock and fresh semi-coke were classified as of “high acute toxic hazard”, whereas aged semi-coke and most of the polluted soils were classified as of “acute toxic hazard”. Analysis of the soil slurries by using the photobacterial solid-phase flash assay showed the presence of particle-bound toxicity in most samples. In the case of four samples out of the eight, chemical and toxicological evaluations both showed that the levels of PAHs, oil products or both exceeded their respective permitted limit values for the living zone (20mg PAHs/kg and 500mg oil products/kg); the toxicity tests showed a toxic hazard. However, in the case of three samples, the chemical and toxicological hazard predictions differed markedly: polluted soil from the Erra River bank contained 2334mg oil/kg, but did not show any water-extractable toxicity. In contrast, spent rock and aged semi-coke that contained none of the pollutants in hazardous concentrations, showed adverse effects in toxicity tests. The environmental hazard of solid waste deposits from the oil shale industry needs further assessment.
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