CEA presented four posters at the recent SETAC virtual conference (SETAC SciCon, 3-7 May 2020). Over the coming weeks we will be showcasing each of these posters in a 'SETAC Spotlight' article. This week it is:
Using historical control data to contextualise the variability in ecotoxicity studies
Ecotoxicity studies, undertaken to address the risks from potential exposure to chemicals, vary in their design e.g. duration of exposure, effect types and endpoints measured. The biological responses measured can be highly variable, with limited opportunity for control of extrinsic sources of variability. It is critical to distinguish between treatment-related effects and background ‘normal variability’ when interpreting results. This is particularly difficult for studies with low replication and/or reduced concentration ranges (e.g. vertebrate studies, field or semi-field studies) where statistical power can be low due to limitations in study design. For these types of studies, historical control data (HCD) can be a valuable tool in contextualising results from single studies against previous studies performed under similar conditions.
This poster discusses the case for better use of HCD in ecotoxicology assessments, illustrating with three case studies the value and difficulties of using HCD in interpretation of results of standard (avian reproduction; non-target terrestrial plant) and higher-tier (aquatic mesocosm) study designs. The possible reasons for HCD being routinely used in mammalian toxicology for human health assessments but not directly in ecotoxicology are also discussed e.g., different data types, the potential to mask effects, and the lack of guidance.
The aim of this poster is to raise awareness regarding this topic and to encourage organisations such as OECD, EFSA and USEPA to develop guidance on the principles of HCD collection so better use can be made of this potentially valuable tool.
You can download our poster here (Using historical control data to contextualise the variability in ecotoxicity studies). For further information, please contact Amy.Brooks@cea-res.co.uk.
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