October 28, 2015 by Becky Brown
In January 2013 a workshop was hosted by ILSI Heath and Environmental Sciences Institute (HESI), in Miami, Florida, USA on ‘Bioaccumulation of organic chemicals in terrestrial environments’. The aims of the meeting were to identify and expand on existing methods, consider data gaps and where necessary propose new methods for both prospective and retrospective risk assessment of organic chemical bioaccumulation in terrestrial environments. The first of a series of papers from this workshop have now been published in Integrated Environmental Assessment and Management (IEAM).
The first paper (Hoke et al. 2015) focuses on laboratory based methods for assessing terrestrial bioaccumulation and considers if assessment of bioaccumulation potential in aquatic organisms can be extrapolated to protect terrestrial organisms and ecosystems. Where possible terrestrial bioaccumulation testing should be based on the relevant exposure pathway and on the physical-chemical and environmental fate properties of substances but additional unnecessary animal testing should be avoided. It is suggested that in vitro biotransformation tests similar to those available for fish species could be developed or refined for higher terrestrial species (e.g. quail or mallard ducks) to determine the potential for substances to be metabolised in these animals. There already exists a standard test method for considering bioaccumulation in earthworms (OECD 317). Plants are one of the most important exposure pathways from soil contamination into the food web and it is recommended that efforts should be made to develop standard regulatory test guidelines to address bioaccumulation in non-crop plants (this could be an adaptation or extension of existing residue methods with crop plant species used for pesticide assessment). Finally, the paper stresses the need for scientific and regulatory consensus on relevant and meaningful metrics for the expression and evaluation of the potential for bioaccumulation in terrestrial organisms and food chains e.g. fugacity analysis (as proposed by Burkhard et al. 2012 for aquatic systems).
A second publication (Gobas et al. 2015) reviews the modelling approaches that can be used for assessing bioaccumulation in terrestrial environments. Although terrestrial models exist there are data gaps including a lack of QSARS and models for important terrestrial species such as insects and reptiles. The lack of standardised non-crop plant models is also data gap. Finally there is a lack of field data for validating bioaccumulation models. A review of the evidence for terrestrial bioaccumulation from field studies will form the basis of a future publication.