The basis for an ecological risk assessment based on meeting the needs of recent UK and EU legislation is described. The background to the framework and the legislative driver and relevant definitions of harm are provided, prior to an overview of the proposed ecological risk assessment process, which has been broken down into a Tiered approach. Tier 0 requires the establishment of a conceptual site model, where potential contaminant-pathway-receptor linkages are sought and, assuming they are identified, lead on to higher Tier assessments. Tier 1 relies largely on chemical analysis of soil contaminant levels and comparison with soil quality guideline values to assess the likelihood of harm. In some cases biological screening assays may also be undertaken within this Tier. Based on a weight of evidence approach, should data from Tier 1 indicate harm or leave uncertainty, then Tier 2 biological testing is undertaken using assays relevant to the site of interest. In situations where harm is identified under Tier 2 then Tier 3 is reserved for establishing the extent of harm within the ecosystem. Finally the use of the 'weight-of-evidence' approach to generate scientifically robust conclusions regarding the harm (or potential for harm) within the ecosystem is briefly outlined. The framework discussed is currently being adopted by the UK Environment Agency, with implementation expected in 2005. The UK scheme compares favourably with comparative schemes operating in other countries possessing the merits of being iterative, tiered, flexible with agreed exit points subject to satisfying defined criteria and so speeding the decision-making process.

The response of ‘Era’ (tolerant) and ‘Coteau’ (susceptible) hard red spring wheat (Triticum aestivum L.) to CGA-82725 2-propynyl ester of {2-[4- [(3,5-dichloro-2-pyridinyl)oxy] phenoxy] propanoic acid} was determined in field and greenhouse evaluations. Era wheat was most susceptible to CGA-82725 applied at early jointing through the boot stage. Coteau wheat was most susceptible at die two-leaf stage and between early jointing through spike emergence. Coteau was injured more than Era wheat as the CGA-82725 rate was increased from 0.14 to 0.28 kg ai/ha. Wheat grain yield reductions were greatest when CGA-82725 was applied at the early jointing through boot stage for both cultivars and averaged 73% of the control. Absorption and translocation of 14C-CGA-82725 were similar and increased over time regardless of cultivar. Most of the absorbed 14C remained in the treated leaf in both cultivars.