Operator exposure models, predicted

UK-POEM UK PREDICTIVE OPERATOR EXPOSURE MODEL General Description 183 Formulations and Use Scenarios 183 Use in Risk Assessment 184 Exposure Reduction Measures 186 Model Updates 186 Comments on the Model 186 DUTCH MODEL 187 General Description 187 Formulations and Use Scenarios 187 Use in Risk Assessment 188 Exposure Reduction Measures 189 Model Updates 189 Comments on the Model 189 EUROPOEM DATABASE 189 General Description 189 Formulations and Use Scenarios 190 Use in Risk Assessment 192 Exposure Reduction Measures 194 Model Updates 194 Comments on the Model 194... 

EUROPOEM (1996). The Development, Maintenance and Dissemination of a European Predictive Operator Exposure Model (EUROPOEM) Database, AIR3 CT93-1370, TNO-BIBRA International, Carshalton, Survey, UK. 

POEM (1992). UK Predictive Operator Exposure Model (POEM) A Users Guide, Pesticides Safety Directorate, York, UK. 

The establishment of a statistically sound data-set on usage allows an evaluation of likely operator exposure, as realistic work rates can be derived from the data collected, such as average field size, area sprayed per operator per day, amount of pesticide handled per day, etc. All of these factors are vital in refining predicted operator exposure models, and are discussed at length by Hamey (2001). 

Kangas, J. and S. Sihvonen (1996). Comparison of Predictive Models for Pesticide Operator Exposure, TemaNord 560, Nordic Council of Ministers, Copenhagen, Denmark. 

The predictive models aim to produce real measurable parameters that can then be monitored. If the measured variable starts to diverge from the predicted value the life prediction can be amended. However, the monitoring may still identify unexpected changes in the operating parameters rather than in the material. Post-exposure testing of extracted specimens can be performed, but, as some level of acceleration is required, the conditions will never be the same as if the component or specimen had continued in service. 

For the purposes of the BPD a project was commissioned by DG Environment and conducted by Institutes/ organisations from 6 European Member States, together with representatives from industry. The aims of this project were to develop relevant exposure scenarios of humans to biocidal products and to develop operational predictive models for the purposes of authorisation of biocidal products in each of the 23 product types. The report and proposed models from this project is expected to be finalised in mid-2003. 

Carburization damage is mainly associated with high-temperature exposure to carbon dioxide, methane, and other hydrocarbons. Heat-treating equipment used for gas carburization (surface hardening) of steels is also vulnerable. An insidious aspect of carburization is its nonuniform nature. Just as for other forms of localized corrosion, it is extremely difficult to predict and model localized carburization damage. As a rule of thumb, carburization problems only occur at temperatures above 815°C, because of unfavorable kinetics at lower temperatures. Carburization is therefore not a common occurrence in most refining operations because of the relatively low tube temperatures of most refinery-fired heaters. 

---