Nontarget

Chromatographic peak areas are calculated automatically by the data system by reference to the response obtained from certain specified, compound-dependent ions. From the peak areas of the target compounds, quantification is achieved by comparison with the internal standards, which are present in known concentration. The laboratory responsible for the analysis must report the target compounds and all tentatively identified (nontarget) compounds. Standard EPA forms must be completed and submitted. A laboratory is said to be in compliance when it has satisfied all aspects of its CLP contract. 

An effective therapeutic agent must also have the abiUty to reach its target sequence m vivo. BioavailabiUty requires that the antisense oligonucleotide be able to pass through the cell membrane, and that it have a low affinity for nontarget cellular compartments and, in animal systems, nontarget organs. 

Bio accumulation studies in aquatic nontarget organisms (field)... 

The result is that more than 99.9% of the applied pesticide drifts off into the environment where it adversely affects nontarget... 

Tables 2.6 and 2.7 give examples of the modes of action of pollutants in animals and in plants/fungi, respectively. It is noteworthy that many of the chemicals represented are pesticides. Pesticides are designed to be toxic to target species. On the other hand, manufacturers seek to minimize toxicity to humans, beneficial organisms and, more generally, nontarget species. Selective toxicity is an important issue. Regardful of the potential risks associated with the release of bioactive compounds into the environment, regulatory authorities usually require evidence of the mode of toxic action before pesticides can be marketed. Other industrial chemicals are not subject to such strict regulatory requirements, and their mode of action is frequently unknown.

Regarding soils, a central issue is the persistence and movement of pesticides that are widely used in agriculture. Many different insecticides, fungicides, herbicides, and molluscicides are applied to agricultural soils, and there is concern not only about effects that they may have on nontarget species residing in soil, but also on the possibility of the chemicals finding their way into adjacent water courses. 

When used to control rodents and predatory mammals in conserved areas, they have caused both primary and secondary poisoning of nontarget species, sometimes associated with population declines. 

There is a shortage of appropriate texts on the ARs. Buckle and Smith (1994) and Mechin (1986) describe the use of ARs in rodent control. Thijssen (1995) gives a concise account of mode of action and resistance mechanisms. For effects on nontarget species, reference should be made to the individual citations given in the foregoing text. 

The following brief account identifies only major groups of herbicides not mentioned elsewhere in the text, and is far from comprehensive. Their mode of action is only dealt with in a superficial way. From an ecotoxicological point of view, there has not been as much concern about their sublethal effects upon plants as there has been in the case of mammals, and there has not been a strong interest in the development of biomarker assays to establish their effects. The major concern has been whether weeds, or nontarget plants, have been removed following herbicide application—a rather easy matter to establish as plants are fairly sedentary. For a more detailed account of herbicide chemistry and biochemistry, see Hassall (1990). 

Inadequate performance may result from lack of antigen specificity, e.g., tumor-specific antigens are often differentiation antigens which also occur, although in a lower density on nontarget cells (Poste, 1984). 

Impacts of Low-Dose, Eligh-Potency Eterbicides on Nontarget and Unintended Plant Species... 

At present no a.i. is known to have an unacceptable impact on nontarget organisms assessed in the authorization procedure in the concentration range below 0.05 mgkg ... 

In the case of surface water, the LOQ must not exceed a concentration which has an impact on nontarget organisms deemed to be unacceptable according to the requirements of Annex VI. At present, no harmonized limits for surface water exist. Therefore, provisions in Annex VI of Directive 91/414/EEC will be used to calculate guidance limits for analytical methods for surface water. In SANCO/825/00 the limits given in Table 6 are established [the relevant concentrations (the lowest will always be taken into consideration) depend on the species as indicated and can be taken from toxicity tests]. 

The method must be capable of determining all components (a.i. and relevant/major metabolites) that are included in the residue definitions used in the assessment of risk to nontarget organisms. For ground (drinking) water and air, the risk to con-sumers/operators or bystanders must also be considered. 

The first step in a wildlife exposure assessment is to document the occurrence and persistence of a pesticide in the study area throughout the study duration. Several articles in this book describe the experimental designs and best practices to conduct field crop and environmental dissipation (air, soil and water) studies. This article presents methods to quantify spatial and temporal distributions of pesticide presence in ecosystems following normal application and resultant exposure of nontarget wildlife. 

---