Trigger values

Force curve gives the relationship between the z-piezo displacement and the cantilever deflection as shown in Figure 21.10b. When a cantilever approaches to a stiff sample surface, cantilever deflection. A, is equal to the z-piezo displacement, z — Zo- The value of zo is defined as the position where the tip-sample contact is realized. On the other hand, z-piezo displacement becomes larger to achieve the preset trigger value (set point) of the cantilever deflection in the case of an elastic sample due to the deformation of the sample itself. In other words, we can obtain information about a sample deformation, 8, from the force-distance curve of the elastic surface by the following relationship ... 

Campbell PJ, Brown KC, Harrison EG et al (2000) A hazard quotient approach for assessing the risk to non-target arthropods from plant protection products under 91/414/EEC hazard quotient trigger value proposal and validation. J Pest Sci 73 117-124... 

Trigger values, action values and requirements for warding off harmful changes and remediations... 

The relevant proper authority shall take appropriate measures to determine the facts, if the authority is aware of indications of a harmful soil change or contaminated site, and where hazardous substance values exceed the relevant trigger values, the authority must take the necessary measures to determine whether or not there is a harmful soil change or a contaminated site, and to inform the owner or occupant of the property of the result of investigation and assessment, upon application, in writing (Article 9(1)). 

Evaluation, using trigger values and action values (Tables 9 to 17) Remediation investigation and planning... 

Table 9. (BBodSchV - Annex 2, p. 51) Soil - Human Health Pathway - Trigger Values.

Substance Trigger value (mg/kg dry matter, fine soil, in ammonium nitrate extract)... 

Substance Method Trigger value Action value... 

In the case of soils with temporarily decreasing conditions, a trigger value of50 mg/kg dry matter must be applied. 

Table 16. (BBodSchV annex 2, 2.2, p.52) Soil - Plant Pathway Action and Trigger Values Agriculture, vegetable garden.

In the case of using SSD methodology, when there are data gaps, the outcome of the analysis can trigger additional research for further site-directed assessments. SSDs derived using limited data sets not fulfilling data quantity criteria defined in different jurisdictions should only be used as trigger values and the inherent uncertainty of the output explicitly stated. ... 

Ecotoxicity can only be measured by the application of biological methods, whereas chemical analysis determines concentrations of defined chemicals that may be used to deduce toxic effects. All concentration levels such as screening values, guideline values, threshold concentrations, benchmark concentrations and trigger values used for the assessment of contaminated media (water, soil, sediments, etc.) should ideally be derived from the observation of biological effects. Comparing pollutant concentrations with these usually conservative standard values is a common practice in the preliminary assessment of contaminated sites. The integration of further information, such as ecotoxicity data from the site, can improve the risk assessment process and enable a more reliable prediction of environmental threats. 

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). 

In the aquatic risk assessments, 16 out of 50 substances met the regulatory trigger values in a first-tier risk assessment. For 34 substances the trigger was not met without consideration of no-spray buffer zones and/or further risk refinement. 

C. C. Ferguson and J. Denner, Developing Guideline (Trigger) Values for Contaminants in Soil Underlying Risk Analysis and Risk Management Concepts, Land Contam. Reclam., 1994,2,117-123. 

The main concern of waste management and long term stabilization is to confine the residues in order to reduce the dispersion of contaminants to concentrations that not exceed the trigger values considered to be safe there is thus a need to ensure that the environmental and health risk from these materials are reduced to an acceptable level. However, the confinement will always represent a potential source of environmental contamination to the air, soil, superficial water and groundwater, due to the contaminants release and transport in the environment, which may occur by natural erosion agents like rainfall or wind. 

In accordance with the requirements of Annex VI of 91/414/EEC [7], where the basic principles for decision-making are laid down, Toxicity/Exposure Ratios (TER) are to be calculated. Uncertainty factors of 10 (chronic risk) and 100 (acute risk) must be applied for aquatic organisms. For terrestrial organisms, imcertainty factors of 5 and 10 are to be used, respectively. Different approaches exist for the in-crop area and non-target arthropods and bees in general. Uncertainty arises mainly from the fact that only for a few representative species toxicity data are available. If these trigger values are not breached, a listing of an active substance on Annex I or an authorization of a formulated product respectively are possible. 

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