Chemical categorization pesticides

Another important consideration in the selection of a test set is to ensure that the chemicals in the data set relate to the real problem in question. It should be emphasized that the QSAR models developed in our project are used primarily to predict the activity of environmental chemicals, mostly pesticides and industrial chemicals. A data set reported by Nishihara et al. (Nishihara et al., 2000) was also selected as a test set. This data set contains 517 chemicals tested with the yeast two-hybrid assay, of which over 86% are pesticides and industrial chemicals. Only 463 chemicals were used for this validation study after structure processing. Only 62 chemicals were categorized as active on the basis of having on activity greater than 10% of 10 7M H2, as defined in the original paper (Nishihara et al., 2000). The majority of the chemicals were inactive, which is similar to the real-world situation where inactive chemicals are expected from a large proportion of those in the environment. 

Under current regulations, chemicals allowed for use in various European countries (Table 3) are either fully Hcensed for aquacultural use (oxytetracycline, oxolinic acid) or can be prescribed by veterinarians if they are Hcensed for use on other food animals (14—16). In addition, previously unHcensed chemicals that are appHed to the water (topicals) may now be used under a grandfather clause if no one questions their safety. The question of whether a chemical is a medicine or a pesticide has also been addressed. Eor example, dichlorvos (Nuvan 500 EC) was initially designated as a pesticide in the United Kingdom, but was later categorized as a medicine. A similar product, trichlorfon (Masoten), was treated the same way in the United States. 

The data required for the risk assessment in relation to human health can be categorized as data on the identity of the substance, its physico-chemical and toxicological properties, and on exposure. The minimum data set required for a risk assessment depends on the chemical use category (industrial chemical, pesticide, biocide, food additive, food contact material, etc.), the regulation involved, and the goal of the risk assessment. This chapter will focus on the data used in the hazard assessment. 

Pesticides include many types of chemicals that are spread around in the environment to kill some specific sort of pest, usually insects (insecticides), weeds (herbicides), or fungi (fungicides).2 The total worldwide use of pesticides is now about a million tonnes per year. Historically, insecticides have gone through several generations, which we will categorize as follows ... 

From the perspective of protective clothing selection and chemical resistance, the pesticide formulation types may be more generally categorized as ... 

A second classification categorizes the pesticides according to their chemical nature,... 

Pesticides are chemicals that kill pests, and are categorized by the types of pests they kill. For example, insecticides kill insects, herbicides kill weeds, bactericides kill bacteria, fungicides kill fungi, and algicides kill algae. 

The extent of the threat to aquatic organisms by particular groups of pesticides categorized according to chemical composition is shown in Table 9.4 [27]. From the table it is obvious that chlorinated hydrocarbons... 

For environmental application of pesticide delivery, CRF have been traditionally divided into chemical and physical types (9). More recently, a third approach the biological approach, has appeared, partly in response to delivery requirements for genetically engineered pesticides. The t5q>es of CRF described to date can be categorized as follows ... 

Figure 9.2 Hierarchical categorization of priority target analytes for food and water. The rectangular boxes contain specific examples of pathogens, parasites, toxins, and pesticides (Reproduced with permission from [15]. Copyright 2012, American Chemical Society)...

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