Refined Risk Assessments

The risk assessment is conducted in two tiers. In the first tier, fixed conservative default input parameters given in the EU Guidance Document SANCO 4145/2000 are used for the ETE-calculation [1], The first tier is meant to be a screening process, selecting uncritical products and uses that will pass the process fast and easily. However, experience shows that actually about 75% of the first tier risk assessments do not pass one of the TER-trigger values. When a product does not pass the Tier 1, it enters the higher tier or refined risk assessment. In the Tier 2, a full justification is needed for all assumptions which differ from the Tier 1 default values. 

Several data sources for a refinement of risk assessments for birds and mammals can be used (1) information from other parts of the data package, for example, from the residue section of the dossier, (2) data from scientific literature or official research projects [e.g., CSL (DEFRA-UK) projects on wildlife in agricultural landscape], (3) results from (generic) field studies, which can obtain very focused data sets for refinements (to refine focal species (FIR/bw), PT, PD or RUD (e.g., arthropods)). In all cases, it is necessary to quantify parameters so that they can be used in the ETE-calculation. 

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In 1958, in response to the increased awareness that chemicals can cause cancer, the US Congress passed the Delaney clause, which prohibited the addition to the food supply of any substance known to cause cancer in animals or humans. Compared with today s standards, the analytical methods to detect a potentially harmful substance were very poor. As the analytical methods improved, it became apparent that the food supply had low levels of substances that were known to cause cancer in either animals or humans. The obvious question was Is a small amount of a substance safe to consume. This question in turn raised many others about how to interpret data or extrapolate data to very low doses. The 1970s saw a flourishing of activity to develop and refine risk assessment methodologies. 

For birds, the regulatory trigger values of Annex VI of Council Directive 91/414/ EEC (European Commission 1997) were not met in a first-tier risk assessment for 37 substances out of 50. For most of those substances a refined risk assessment was submitted there were only a few exceptions where applicants did not provide any further risk refinement, or they submitted it too late for it to be taken into consideration in the peer review. The usual options for risk refinement are refinements of selected focal species, for example, proportion of diet taken from the treated area (PT), proportion of different food types taken in the treated area (PD), and measured residues in food items (R). 

Refined risk assessments for 51 uses (several representative uses proposed for most substances) were peer reviewed. Of these assessments, 25 were accepted and... 

A refined risk assessment and specific higher-tiered studies related to this assessment (e.g., field studies) should not only demonstrate that no unacceptable effects on birds/mammals occur under practical conditions of use, but also demonstrate why those effects will not occur. One possibility to describe the... 

As an example for the use of field data (in this case, a combination of a generic study, a field-effect study and a field residue study), the following case study is presented the agricultural scenario was a spray application of an organothio-phosphate insecticide in arable crops. Due to the inherent bird toxicity (e.g., LDjq 10 mg a.s./kg bw) estimated according to the EU Guidance Document SANCO/4145/2000, the acute TER is < 0.5 within a Tier 1 risk assessment [1]. Since the trigger value within the EU (> 10) is not met, a refined risk assessment is necessary. As a consequence, a field study was conducted to derive refined exposure parameters for small insectivorous birds in an arable crop. Furthermore, the effects of the product on the population were recorded. The field work of the... 

Based on data for a relevant indicator species, refined values for body weight, fraction of diet obtained in treated area (PT) and fraction of food type in diet (PD), a refined TER was calculated. As a result of the intensive field work, a set of realistic dietary exposure levels could be calculated for the birds which were observed within 1-10 days after the application of the respective pesticide, resulting in acute TER-values between 12 and 697. These acute TER values, which substantially exceed the value obtained in the Tier 1 assessment (acute TER < 0.5), are all higher than the trigger of 10 set by Annex VI of Directive 91 /414 EEC for a refined risk assessment. Furthermore, pesticide exposure did not adversely affect avian survival (neither adults nor young birds). In conclusion, an unacceptable risk for birds following the use of the compound under practical field conditions is not to be expected. 

Field studies are highly recommended to provide ecological (generic) data on potentially exposed wildlife species for refined risk assessments. As can be seen from the case study, the required input data (generic and/or compound specific) on relevant species and crop scenarios can be generated by tailor-made field studies. These quantitative data are very suitable for ETE-calculations. Therefore, specific data obtained from field studies may contribute to more scientific and realistic risk evaluations. 

Rasmussen (2004b) and Rasmussen et al. (2008) showed that differences in metal concentrations between indoor dust and outdoor soil may become magnified when metal bioaccessibility is considered, depending on the sources of the element and its speciation. Particularly in residential environments where anomalously high metal concentrations are encountered, it is important to elucidate metal speciation in order to refine risk assessments of metal contaminants. Advanced... 

We concluded that in utero exposure to organic solvents is associated with poorer performance on some specific subtle measures of neurocognitive function, language, and behavior. Reducing exposure in pregnancy is merited until more refined risk assessment is possible. Further studies that address exposure to specific solvents, dose, and gestational timing of exposure are needed. 

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